/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=2 et sw=2 tw=80: */ /* This Source Code is subject to the terms of the Mozilla Public License * version 2.0 (the "License"). You can obtain a copy of the License at * http://mozilla.org/MPL/2.0/. */ /* rendering object for CSS "display: flex" */ #include "mozilla/UniquePtr.h" #include "nsFlexContainerFrame.h" #include "nsContentUtils.h" #include "nsCSSAnonBoxes.h" #include "nsDisplayList.h" #include "nsIFrameInlines.h" #include "nsLayoutUtils.h" #include "nsPlaceholderFrame.h" #include "nsPresContext.h" #include "nsRenderingContext.h" #include "nsStyleContext.h" #include "mozilla/Logging.h" #include <algorithm> #include "mozilla/LinkedList.h" #include "mozilla/FloatingPoint.h" #include "WritingModes.h" using namespace mozilla; using namespace mozilla::layout; // Convenience typedefs for helper classes that we forward-declare in .h file // (so that nsFlexContainerFrame methods can use them as parameters): typedef nsFlexContainerFrame::FlexItem FlexItem; typedef nsFlexContainerFrame::FlexLine FlexLine; typedef nsFlexContainerFrame::FlexboxAxisTracker FlexboxAxisTracker; typedef nsFlexContainerFrame::StrutInfo StrutInfo; static mozilla::LazyLogModule gFlexContainerLog("nsFlexContainerFrame"); // XXXdholbert Some of this helper-stuff should be separated out into a general // "main/cross-axis utils" header, shared by grid & flexbox? // (Particularly when grid gets support for align-*/justify-* properties.) // Helper enums // ============ // Represents a physical orientation for an axis. // The directional suffix indicates the direction in which the axis *grows*. // So e.g. eAxis_LR means a horizontal left-to-right axis, whereas eAxis_BT // means a vertical bottom-to-top axis. // NOTE: The order here is important -- these values are used as indices into // the static array 'kAxisOrientationToSidesMap', defined below. enum AxisOrientationType { eAxis_LR, eAxis_RL, eAxis_TB, eAxis_BT, eNumAxisOrientationTypes // For sizing arrays that use these values as indices }; // Represents one or the other extreme of an axis (e.g. for the main axis, the // main-start vs. main-end edge. // NOTE: The order here is important -- these values are used as indices into // the sub-arrays in 'kAxisOrientationToSidesMap', defined below. enum AxisEdgeType { eAxisEdge_Start, eAxisEdge_End, eNumAxisEdges // For sizing arrays that use these values as indices }; // This array maps each axis orientation to a pair of corresponding // [start, end] physical mozilla::Side values. static const mozilla::Side kAxisOrientationToSidesMap[eNumAxisOrientationTypes][eNumAxisEdges] = { { eSideLeft, eSideRight }, // eAxis_LR { eSideRight, eSideLeft }, // eAxis_RL { eSideTop, eSideBottom }, // eAxis_TB { eSideBottom, eSideTop } // eAxis_BT }; // Helper structs / classes / methods // ================================== // Returns true iff the given nsStyleDisplay has display:-webkit-{inline-}-box. static inline bool IsDisplayValueLegacyBox(const nsStyleDisplay* aStyleDisp) { return aStyleDisp->mDisplay == mozilla::StyleDisplay::WebkitBox || aStyleDisp->mDisplay == mozilla::StyleDisplay::WebkitInlineBox; } // Returns true if aFlexContainer is the frame for an element with // "display:-webkit-box" or "display:-webkit-inline-box". aFlexContainer is // expected to be an instance of nsFlexContainerFrame (enforced with an assert); // otherwise, this function's state-bit-check here is bogus. static bool IsLegacyBox(const nsIFrame* aFlexContainer) { MOZ_ASSERT(aFlexContainer->GetType() == nsGkAtoms::flexContainerFrame, "only flex containers may be passed to this function"); return aFlexContainer->HasAnyStateBits(NS_STATE_FLEX_IS_LEGACY_WEBKIT_BOX); } // Returns the "align-items" value that's equivalent to the legacy "box-align" // value in the given style struct. static uint8_t ConvertLegacyStyleToAlignItems(const nsStyleXUL* aStyleXUL) { // -[moz|webkit]-box-align corresponds to modern "align-items" switch (aStyleXUL->mBoxAlign) { case StyleBoxAlign::Stretch: return NS_STYLE_ALIGN_STRETCH; case StyleBoxAlign::Start: return NS_STYLE_ALIGN_FLEX_START; case StyleBoxAlign::Center: return NS_STYLE_ALIGN_CENTER; case StyleBoxAlign::Baseline: return NS_STYLE_ALIGN_BASELINE; case StyleBoxAlign::End: return NS_STYLE_ALIGN_FLEX_END; } MOZ_ASSERT_UNREACHABLE("Unrecognized mBoxAlign enum value"); // Fall back to default value of "align-items" property: return NS_STYLE_ALIGN_STRETCH; } // Returns the "justify-content" value that's equivalent to the legacy // "box-pack" value in the given style struct. static uint8_t ConvertLegacyStyleToJustifyContent(const nsStyleXUL* aStyleXUL) { // -[moz|webkit]-box-pack corresponds to modern "justify-content" switch (aStyleXUL->mBoxPack) { case StyleBoxPack::Start: return NS_STYLE_ALIGN_FLEX_START; case StyleBoxPack::Center: return NS_STYLE_ALIGN_CENTER; case StyleBoxPack::End: return NS_STYLE_ALIGN_FLEX_END; case StyleBoxPack::Justify: return NS_STYLE_ALIGN_SPACE_BETWEEN; } MOZ_ASSERT_UNREACHABLE("Unrecognized mBoxPack enum value"); // Fall back to default value of "justify-content" property: return NS_STYLE_ALIGN_FLEX_START; } // Indicates whether advancing along the given axis is equivalent to // increasing our X or Y position (as opposed to decreasing it). static inline bool AxisGrowsInPositiveDirection(AxisOrientationType aAxis) { return eAxis_LR == aAxis || eAxis_TB == aAxis; } // Given an AxisOrientationType, returns the "reverse" AxisOrientationType // (in the same dimension, but the opposite direction) static inline AxisOrientationType GetReverseAxis(AxisOrientationType aAxis) { AxisOrientationType reversedAxis; if (aAxis % 2 == 0) { // even enum value. Add 1 to reverse. reversedAxis = AxisOrientationType(aAxis + 1); } else { // odd enum value. Subtract 1 to reverse. reversedAxis = AxisOrientationType(aAxis - 1); } // Check that we're still in the enum's valid range MOZ_ASSERT(reversedAxis >= eAxis_LR && reversedAxis <= eAxis_BT); return reversedAxis; } /** * Converts a "flex-relative" coordinate in a single axis (a main- or cross-axis * coordinate) into a coordinate in the corresponding physical (x or y) axis. If * the flex-relative axis in question already maps *directly* to a physical * axis (i.e. if it's LTR or TTB), then the physical coordinate has the same * numeric value as the provided flex-relative coordinate. Otherwise, we have to * subtract the flex-relative coordinate from the flex container's size in that * axis, to flip the polarity. (So e.g. a main-axis position of 2px in a RTL * 20px-wide container would correspond to a physical coordinate (x-value) of * 18px.) */ static nscoord PhysicalCoordFromFlexRelativeCoord(nscoord aFlexRelativeCoord, nscoord aContainerSize, AxisOrientationType aAxis) { if (AxisGrowsInPositiveDirection(aAxis)) { return aFlexRelativeCoord; } return aContainerSize - aFlexRelativeCoord; } // Helper-macro to let us pick one of two expressions to evaluate // (a width expression vs. a height expression), to get a main-axis or // cross-axis component. // For code that has e.g. a nsSize object, FlexboxAxisTracker::GetMainComponent // and GetCrossComponent are cleaner; but in cases where we simply have // two separate expressions for width and height (which may be expensive to // evaluate), these macros will ensure that only the expression for the correct // axis gets evaluated. #define GET_MAIN_COMPONENT(axisTracker_, width_, height_) \ (axisTracker_).IsMainAxisHorizontal() ? (width_) : (height_) #define GET_CROSS_COMPONENT(axisTracker_, width_, height_) \ (axisTracker_).IsCrossAxisHorizontal() ? (width_) : (height_) // Logical versions of helper-macros above: #define GET_MAIN_COMPONENT_LOGICAL(axisTracker_, wm_, isize_, bsize_) \ wm_.IsOrthogonalTo(axisTracker_.GetWritingMode()) != \ (axisTracker_).IsRowOriented() ? (isize_) : (bsize_) #define GET_CROSS_COMPONENT_LOGICAL(axisTracker_, wm_, isize_, bsize_) \ wm_.IsOrthogonalTo(axisTracker_.GetWritingMode()) != \ (axisTracker_).IsRowOriented() ? (bsize_) : (isize_) // Flags to customize behavior of the FlexboxAxisTracker constructor: enum AxisTrackerFlags { eNoFlags = 0x0, // Normally, FlexboxAxisTracker may attempt to reverse axes & iteration order // to avoid bottom-to-top child ordering, for saner pagination. This flag // suppresses that behavior (so that we allow bottom-to-top child ordering). // (This may be helpful e.g. when we're only dealing with a single child.) eAllowBottomToTopChildOrdering = 0x1 }; MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(AxisTrackerFlags) // Encapsulates our flex container's main & cross axes. class MOZ_STACK_CLASS nsFlexContainerFrame::FlexboxAxisTracker { public: FlexboxAxisTracker(const nsFlexContainerFrame* aFlexContainer, const WritingMode& aWM, AxisTrackerFlags aFlags = eNoFlags); // Accessors: // XXXdholbert [BEGIN DEPRECATED] AxisOrientationType GetMainAxis() const { return mMainAxis; } AxisOrientationType GetCrossAxis() const { return mCrossAxis; } bool IsMainAxisHorizontal() const { // If we're row-oriented, and our writing mode is NOT vertical, // or we're column-oriented and our writing mode IS vertical, // then our main axis is horizontal. This handles all cases: return mIsRowOriented != mWM.IsVertical(); } bool IsCrossAxisHorizontal() const { return !IsMainAxisHorizontal(); } // XXXdholbert [END DEPRECATED] // Returns the flex container's writing mode. WritingMode GetWritingMode() const { return mWM; } // Returns true if our main axis is in the reverse direction of our // writing mode's corresponding axis. (From 'flex-direction: *-reverse') bool IsMainAxisReversed() const { return mIsMainAxisReversed; } // Returns true if our cross axis is in the reverse direction of our // writing mode's corresponding axis. (From 'flex-wrap: *-reverse') bool IsCrossAxisReversed() const { return mIsCrossAxisReversed; } bool IsRowOriented() const { return mIsRowOriented; } bool IsColumnOriented() const { return !mIsRowOriented; } nscoord GetMainComponent(const nsSize& aSize) const { return GET_MAIN_COMPONENT(*this, aSize.width, aSize.height); } int32_t GetMainComponent(const LayoutDeviceIntSize& aIntSize) const { return GET_MAIN_COMPONENT(*this, aIntSize.width, aIntSize.height); } nscoord GetCrossComponent(const nsSize& aSize) const { return GET_CROSS_COMPONENT(*this, aSize.width, aSize.height); } int32_t GetCrossComponent(const LayoutDeviceIntSize& aIntSize) const { return GET_CROSS_COMPONENT(*this, aIntSize.width, aIntSize.height); } nscoord GetMarginSizeInMainAxis(const nsMargin& aMargin) const { return IsMainAxisHorizontal() ? aMargin.LeftRight() : aMargin.TopBottom(); } nscoord GetMarginSizeInCrossAxis(const nsMargin& aMargin) const { return IsCrossAxisHorizontal() ? aMargin.LeftRight() : aMargin.TopBottom(); } // Returns aFrame's computed value for 'height' or 'width' -- whichever is in // the cross-axis. (NOTE: This is cross-axis-specific for now. If we need a // main-axis version as well, we could generalize or clone this function.) const nsStyleCoord& ComputedCrossSize(const nsIFrame* aFrame) const { const nsStylePosition* stylePos = aFrame->StylePosition(); return IsCrossAxisHorizontal() ? stylePos->mWidth : stylePos->mHeight; } /** * Converts a "flex-relative" point (a main-axis & cross-axis coordinate) * into a LogicalPoint, using the flex container's writing mode. * * @arg aMainCoord The main-axis coordinate -- i.e an offset from the * main-start edge of the flex container's content box. * @arg aCrossCoord The cross-axis coordinate -- i.e an offset from the * cross-start edge of the flex container's content box. * @arg aContainerMainSize The main size of flex container's content box. * @arg aContainerCrossSize The cross size of flex container's content box. * @return A LogicalPoint, with the flex container's writing mode, that * represents the same position. The logical coordinates are * relative to the flex container's content box. */ LogicalPoint LogicalPointFromFlexRelativePoint(nscoord aMainCoord, nscoord aCrossCoord, nscoord aContainerMainSize, nscoord aContainerCrossSize) const { nscoord logicalCoordInMainAxis = mIsMainAxisReversed ? aContainerMainSize - aMainCoord : aMainCoord; nscoord logicalCoordInCrossAxis = mIsCrossAxisReversed ? aContainerCrossSize - aCrossCoord : aCrossCoord; return mIsRowOriented ? LogicalPoint(mWM, logicalCoordInMainAxis, logicalCoordInCrossAxis) : LogicalPoint(mWM, logicalCoordInCrossAxis, logicalCoordInMainAxis); } /** * Converts a "flex-relative" size (a main-axis & cross-axis size) * into a LogicalSize, using the flex container's writing mode. * * @arg aMainSize The main-axis size. * @arg aCrossSize The cross-axis size. * @return A LogicalSize, with the flex container's writing mode, that * represents the same size. */ LogicalSize LogicalSizeFromFlexRelativeSizes(nscoord aMainSize, nscoord aCrossSize) const { return mIsRowOriented ? LogicalSize(mWM, aMainSize, aCrossSize) : LogicalSize(mWM, aCrossSize, aMainSize); } // Are my axes reversed with respect to what the author asked for? // (We may reverse the axes in the FlexboxAxisTracker constructor and set // this flag, to avoid reflowing our children in bottom-to-top order.) bool AreAxesInternallyReversed() const { return mAreAxesInternallyReversed; } private: // Delete copy-constructor & reassignment operator, to prevent accidental // (unnecessary) copying. FlexboxAxisTracker(const FlexboxAxisTracker&) = delete; FlexboxAxisTracker& operator=(const FlexboxAxisTracker&) = delete; // Helpers for constructor which determine the orientation of our axes, based // on legacy box properties (-webkit-box-orient, -webkit-box-direction) or // modern flexbox properties (flex-direction, flex-wrap) depending on whether // the flex container is a "legacy box" (as determined by IsLegacyBox). void InitAxesFromLegacyProps(const nsFlexContainerFrame* aFlexContainer); void InitAxesFromModernProps(const nsFlexContainerFrame* aFlexContainer); // XXXdholbert [BEGIN DEPRECATED] AxisOrientationType mMainAxis; AxisOrientationType mCrossAxis; // XXXdholbert [END DEPRECATED] const WritingMode mWM; // The flex container's writing mode. bool mIsRowOriented; // Is our main axis the inline axis? // (Are we 'flex-direction:row[-reverse]'?) bool mIsMainAxisReversed; // Is our main axis in the opposite direction // as mWM's corresponding axis? (e.g. RTL vs LTR) bool mIsCrossAxisReversed; // Is our cross axis in the opposite direction // as mWM's corresponding axis? (e.g. BTT vs TTB) // Implementation detail -- this indicates whether we've decided to // transparently reverse our axes & our child ordering, to avoid having // frames flow from bottom to top in either axis (& to make pagination saner). bool mAreAxesInternallyReversed; }; /** * Represents a flex item. * Includes the various pieces of input that the Flexbox Layout Algorithm uses * to resolve a flexible width. */ class nsFlexContainerFrame::FlexItem : public LinkedListElement<FlexItem> { public: // Normal constructor: FlexItem(ReflowInput& aFlexItemReflowInput, float aFlexGrow, float aFlexShrink, nscoord aMainBaseSize, nscoord aMainMinSize, nscoord aMainMaxSize, nscoord aTentativeCrossSize, nscoord aCrossMinSize, nscoord aCrossMaxSize, const FlexboxAxisTracker& aAxisTracker); // Simplified constructor, to be used only for generating "struts": // (NOTE: This "strut" constructor uses the *container's* writing mode, which // we'll use on this FlexItem instead of the child frame's real writing mode. // This is fine - it doesn't matter what writing mode we use for a // strut, since it won't render any content and we already know its size.) FlexItem(nsIFrame* aChildFrame, nscoord aCrossSize, WritingMode aContainerWM); // Accessors nsIFrame* Frame() const { return mFrame; } nscoord GetFlexBaseSize() const { return mFlexBaseSize; } nscoord GetMainMinSize() const { MOZ_ASSERT(!mNeedsMinSizeAutoResolution, "Someone's using an unresolved 'auto' main min-size"); return mMainMinSize; } nscoord GetMainMaxSize() const { return mMainMaxSize; } // Note: These return the main-axis position and size of our *content box*. nscoord GetMainSize() const { return mMainSize; } nscoord GetMainPosition() const { return mMainPosn; } nscoord GetCrossMinSize() const { return mCrossMinSize; } nscoord GetCrossMaxSize() const { return mCrossMaxSize; } // Note: These return the cross-axis position and size of our *content box*. nscoord GetCrossSize() const { return mCrossSize; } nscoord GetCrossPosition() const { return mCrossPosn; } nscoord ResolvedAscent(bool aUseFirstBaseline) const { if (mAscent == ReflowOutput::ASK_FOR_BASELINE) { // XXXdholbert We should probably be using the *container's* writing-mode // here, instead of the item's -- though it doesn't much matter right // now, because all of the baseline-handling code here essentially // assumes that the container & items have the same writing-mode. This // will matter more (& can be expanded/tested) once we officially support // logical directions & vertical writing-modes in flexbox, in bug 1079155 // or a dependency. // Use GetFirstLineBaseline() or GetLastLineBaseline() as appropriate, // or just GetLogicalBaseline() if that fails. bool found = aUseFirstBaseline ? nsLayoutUtils::GetFirstLineBaseline(mWM, mFrame, &mAscent) : nsLayoutUtils::GetLastLineBaseline(mWM, mFrame, &mAscent); if (!found) { mAscent = mFrame->SynthesizeBaselineBOffsetFromBorderBox(mWM, BaselineSharingGroup::eFirst); } } return mAscent; } // Convenience methods to compute the main & cross size of our *margin-box*. // The caller is responsible for telling us the right axis, so that we can // pull out the appropriate components of our margin/border/padding structs. nscoord GetOuterMainSize(AxisOrientationType aMainAxis) const { return mMainSize + GetMarginBorderPaddingSizeInAxis(aMainAxis); } nscoord GetOuterCrossSize(AxisOrientationType aCrossAxis) const { return mCrossSize + GetMarginBorderPaddingSizeInAxis(aCrossAxis); } // Returns the distance between this FlexItem's baseline and the cross-start // edge of its margin-box. Used in baseline alignment. // (This function needs to be told which edge we're measuring the baseline // from, so that it can look up the appropriate components from mMargin.) nscoord GetBaselineOffsetFromOuterCrossEdge( AxisEdgeType aEdge, const FlexboxAxisTracker& aAxisTracker, bool aUseFirstLineBaseline) const; float GetShareOfWeightSoFar() const { return mShareOfWeightSoFar; } bool IsFrozen() const { return mIsFrozen; } bool HadMinViolation() const { return mHadMinViolation; } bool HadMaxViolation() const { return mHadMaxViolation; } // Indicates whether this item received a preliminary "measuring" reflow // before its actual reflow. bool HadMeasuringReflow() const { return mHadMeasuringReflow; } // Indicates whether this item's cross-size has been stretched (from having // "align-self: stretch" with an auto cross-size and no auto margins in the // cross axis). bool IsStretched() const { return mIsStretched; } // Indicates whether we need to resolve an 'auto' value for the main-axis // min-[width|height] property. bool NeedsMinSizeAutoResolution() const { return mNeedsMinSizeAutoResolution; } // Indicates whether this item is a "strut" left behind by an element with // visibility:collapse. bool IsStrut() const { return mIsStrut; } WritingMode GetWritingMode() const { return mWM; } uint8_t GetAlignSelf() const { return mAlignSelf; } // Returns the flex factor (flex-grow or flex-shrink), depending on // 'aIsUsingFlexGrow'. // // Asserts fatally if called on a frozen item (since frozen items are not // flexible). float GetFlexFactor(bool aIsUsingFlexGrow) { MOZ_ASSERT(!IsFrozen(), "shouldn't need flex factor after item is frozen"); return aIsUsingFlexGrow ? mFlexGrow : mFlexShrink; } // Returns the weight that we should use in the "resolving flexible lengths" // algorithm. If we're using the flex grow factor, we just return that; // otherwise, we return the "scaled flex shrink factor" (scaled by our flex // base size, so that when both large and small items are shrinking, the large // items shrink more). // // I'm calling this a "weight" instead of a "[scaled] flex-[grow|shrink] // factor", to more clearly distinguish it from the actual flex-grow & // flex-shrink factors. // // Asserts fatally if called on a frozen item (since frozen items are not // flexible). float GetWeight(bool aIsUsingFlexGrow) { MOZ_ASSERT(!IsFrozen(), "shouldn't need weight after item is frozen"); if (aIsUsingFlexGrow) { return mFlexGrow; } // We're using flex-shrink --> return mFlexShrink * mFlexBaseSize if (mFlexBaseSize == 0) { // Special-case for mFlexBaseSize == 0 -- we have no room to shrink, so // regardless of mFlexShrink, we should just return 0. // (This is really a special-case for when mFlexShrink is infinity, to // avoid performing mFlexShrink * mFlexBaseSize = inf * 0 = undefined.) return 0.0f; } return mFlexShrink * mFlexBaseSize; } const nsSize& IntrinsicRatio() const { return mIntrinsicRatio; } bool HasIntrinsicRatio() const { return mIntrinsicRatio != nsSize(); } // Getters for margin: // =================== const nsMargin& GetMargin() const { return mMargin; } // Returns the margin component for a given mozilla::Side nscoord GetMarginComponentForSide(mozilla::Side aSide) const { return mMargin.Side(aSide); } // Returns the total space occupied by this item's margins in the given axis nscoord GetMarginSizeInAxis(AxisOrientationType aAxis) const { mozilla::Side startSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_Start]; mozilla::Side endSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_End]; return GetMarginComponentForSide(startSide) + GetMarginComponentForSide(endSide); } // Getters for border/padding // ========================== const nsMargin& GetBorderPadding() const { return mBorderPadding; } // Returns the border+padding component for a given mozilla::Side nscoord GetBorderPaddingComponentForSide(mozilla::Side aSide) const { return mBorderPadding.Side(aSide); } // Returns the total space occupied by this item's borders and padding in // the given axis nscoord GetBorderPaddingSizeInAxis(AxisOrientationType aAxis) const { mozilla::Side startSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_Start]; mozilla::Side endSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_End]; return GetBorderPaddingComponentForSide(startSide) + GetBorderPaddingComponentForSide(endSide); } // Getter for combined margin/border/padding // ========================================= // Returns the total space occupied by this item's margins, borders and // padding in the given axis nscoord GetMarginBorderPaddingSizeInAxis(AxisOrientationType aAxis) const { return GetMarginSizeInAxis(aAxis) + GetBorderPaddingSizeInAxis(aAxis); } // Setters // ======= // Helper to set the resolved value of min-[width|height]:auto for the main // axis. (Should only be used if NeedsMinSizeAutoResolution() returns true.) void UpdateMainMinSize(nscoord aNewMinSize) { NS_ASSERTION(aNewMinSize >= 0, "How did we end up with a negative min-size?"); MOZ_ASSERT(mMainMaxSize >= aNewMinSize, "Should only use this function for resolving min-size:auto, " "and main max-size should be an upper-bound for resolved val"); MOZ_ASSERT(mNeedsMinSizeAutoResolution && (mMainMinSize == 0 || mFrame->IsThemed(mFrame->StyleDisplay())), "Should only use this function for resolving min-size:auto, " "so we shouldn't already have a nonzero min-size established " "(unless it's a themed-widget-imposed minimum size)"); if (aNewMinSize > mMainMinSize) { mMainMinSize = aNewMinSize; // Also clamp main-size to be >= new min-size: mMainSize = std::max(mMainSize, aNewMinSize); } mNeedsMinSizeAutoResolution = false; } // This sets our flex base size, and then sets our main size to the // resulting "hypothetical main size" (the base size clamped to our // main-axis [min,max] sizing constraints). void SetFlexBaseSizeAndMainSize(nscoord aNewFlexBaseSize) { MOZ_ASSERT(!mIsFrozen || mFlexBaseSize == NS_INTRINSICSIZE, "flex base size shouldn't change after we're frozen " "(unless we're just resolving an intrinsic size)"); mFlexBaseSize = aNewFlexBaseSize; // Before we've resolved flexible lengths, we keep mMainSize set to // the 'hypothetical main size', which is the flex base size, clamped // to the [min,max] range: mMainSize = NS_CSS_MINMAX(mFlexBaseSize, mMainMinSize, mMainMaxSize); } // Setters used while we're resolving flexible lengths // --------------------------------------------------- // Sets the main-size of our flex item's content-box. void SetMainSize(nscoord aNewMainSize) { MOZ_ASSERT(!mIsFrozen, "main size shouldn't change after we're frozen"); mMainSize = aNewMainSize; } void SetShareOfWeightSoFar(float aNewShare) { MOZ_ASSERT(!mIsFrozen || aNewShare == 0.0f, "shouldn't be giving this item any share of the weight " "after it's frozen"); mShareOfWeightSoFar = aNewShare; } void Freeze() { mIsFrozen = true; } void SetHadMinViolation() { MOZ_ASSERT(!mIsFrozen, "shouldn't be changing main size & having violations " "after we're frozen"); mHadMinViolation = true; } void SetHadMaxViolation() { MOZ_ASSERT(!mIsFrozen, "shouldn't be changing main size & having violations " "after we're frozen"); mHadMaxViolation = true; } void ClearViolationFlags() { mHadMinViolation = mHadMaxViolation = false; } // Setters for values that are determined after we've resolved our main size // ------------------------------------------------------------------------- // Sets the main-axis position of our flex item's content-box. // (This is the distance between the main-start edge of the flex container // and the main-start edge of the flex item's content-box.) void SetMainPosition(nscoord aPosn) { MOZ_ASSERT(mIsFrozen, "main size should be resolved before this"); mMainPosn = aPosn; } // Sets the cross-size of our flex item's content-box. void SetCrossSize(nscoord aCrossSize) { MOZ_ASSERT(!mIsStretched, "Cross size shouldn't be modified after it's been stretched"); mCrossSize = aCrossSize; } // Sets the cross-axis position of our flex item's content-box. // (This is the distance between the cross-start edge of the flex container // and the cross-start edge of the flex item.) void SetCrossPosition(nscoord aPosn) { MOZ_ASSERT(mIsFrozen, "main size should be resolved before this"); mCrossPosn = aPosn; } // After a FlexItem has had a reflow, this method can be used to cache its // (possibly-unresolved) ascent, in case it's needed later for // baseline-alignment or to establish the container's baseline. // (NOTE: This can be marked 'const' even though it's modifying mAscent, // because mAscent is mutable. It's nice for this to be 'const', because it // means our final reflow can iterate over const FlexItem pointers, and we // can be sure it's not modifying those FlexItems, except via this method.) void SetAscent(nscoord aAscent) const { mAscent = aAscent; // NOTE: this may be ASK_FOR_BASELINE } void SetHadMeasuringReflow() { mHadMeasuringReflow = true; } void SetIsStretched() { MOZ_ASSERT(mIsFrozen, "main size should be resolved before this"); mIsStretched = true; } // Setter for margin components (for resolving "auto" margins) void SetMarginComponentForSide(mozilla::Side aSide, nscoord aLength) { MOZ_ASSERT(mIsFrozen, "main size should be resolved before this"); mMargin.Side(aSide) = aLength; } void ResolveStretchedCrossSize(nscoord aLineCrossSize, const FlexboxAxisTracker& aAxisTracker); uint32_t GetNumAutoMarginsInAxis(AxisOrientationType aAxis) const; // Once the main size has been resolved, should we bother doing layout to // establish the cross size? bool CanMainSizeInfluenceCrossSize(const FlexboxAxisTracker& aAxisTracker) const; protected: // Helper called by the constructor, to set mNeedsMinSizeAutoResolution: void CheckForMinSizeAuto(const ReflowInput& aFlexItemReflowInput, const FlexboxAxisTracker& aAxisTracker); // Our frame: nsIFrame* const mFrame; // Values that we already know in constructor: (and are hence mostly 'const') const float mFlexGrow; const float mFlexShrink; const nsSize mIntrinsicRatio; const nsMargin mBorderPadding; nsMargin mMargin; // non-const because we need to resolve auto margins // These are non-const so that we can lazily update them with the item's // intrinsic size (obtained via a "measuring" reflow), when necessary. // (e.g. for "flex-basis:auto;height:auto" & "min-height:auto") nscoord mFlexBaseSize; nscoord mMainMinSize; nscoord mMainMaxSize; const nscoord mCrossMinSize; const nscoord mCrossMaxSize; // Values that we compute after constructor: nscoord mMainSize; nscoord mMainPosn; nscoord mCrossSize; nscoord mCrossPosn; mutable nscoord mAscent; // Mutable b/c it's set & resolved lazily, sometimes // via const pointer. See comment above SetAscent(). // Temporary state, while we're resolving flexible widths (for our main size) // XXXdholbert To save space, we could use a union to make these variables // overlay the same memory as some other member vars that aren't touched // until after main-size has been resolved. In particular, these could share // memory with mMainPosn through mAscent, and mIsStretched. float mShareOfWeightSoFar; bool mIsFrozen; bool mHadMinViolation; bool mHadMaxViolation; // Misc: bool mHadMeasuringReflow; // Did this item get a preliminary reflow, // to measure its desired height? bool mIsStretched; // See IsStretched() documentation bool mIsStrut; // Is this item a "strut" left behind by an element // with visibility:collapse? // Does this item need to resolve a min-[width|height]:auto (in main-axis). bool mNeedsMinSizeAutoResolution; const WritingMode mWM; // The flex item's writing mode. uint8_t mAlignSelf; // My "align-self" computed value (with "auto" // swapped out for parent"s "align-items" value, // in our constructor). }; /** * Represents a single flex line in a flex container. * Manages a linked list of the FlexItems that are in the line. */ class nsFlexContainerFrame::FlexLine : public LinkedListElement<FlexLine> { public: FlexLine() : mNumItems(0), mNumFrozenItems(0), mTotalInnerHypotheticalMainSize(0), mTotalOuterHypotheticalMainSize(0), mLineCrossSize(0), mFirstBaselineOffset(nscoord_MIN), mLastBaselineOffset(nscoord_MIN) {} // Returns the sum of our FlexItems' outer hypothetical main sizes. // ("outer" = margin-box, and "hypothetical" = before flexing) nscoord GetTotalOuterHypotheticalMainSize() const { return mTotalOuterHypotheticalMainSize; } // Accessors for our FlexItems & information about them: FlexItem* GetFirstItem() { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mItems.getFirst(); } const FlexItem* GetFirstItem() const { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mItems.getFirst(); } FlexItem* GetLastItem() { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mItems.getLast(); } const FlexItem* GetLastItem() const { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mItems.getLast(); } bool IsEmpty() const { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mItems.isEmpty(); } uint32_t NumItems() const { MOZ_ASSERT(mItems.isEmpty() == (mNumItems == 0), "mNumItems bookkeeping is off"); return mNumItems; } // Adds the given FlexItem to our list of items (at the front or back // depending on aShouldInsertAtFront), and adds its hypothetical // outer & inner main sizes to our totals. Use this method instead of // directly modifying the item list, so that our bookkeeping remains correct. void AddItem(FlexItem* aItem, bool aShouldInsertAtFront, nscoord aItemInnerHypotheticalMainSize, nscoord aItemOuterHypotheticalMainSize) { if (aShouldInsertAtFront) { mItems.insertFront(aItem); } else { mItems.insertBack(aItem); } // Update our various bookkeeping member-vars: mNumItems++; if (aItem->IsFrozen()) { mNumFrozenItems++; } mTotalInnerHypotheticalMainSize += aItemInnerHypotheticalMainSize; mTotalOuterHypotheticalMainSize += aItemOuterHypotheticalMainSize; } // Computes the cross-size and baseline position of this FlexLine, based on // its FlexItems. void ComputeCrossSizeAndBaseline(const FlexboxAxisTracker& aAxisTracker); // Returns the cross-size of this line. nscoord GetLineCrossSize() const { return mLineCrossSize; } // Setter for line cross-size -- needed for cases where the flex container // imposes a cross-size on the line. (e.g. for single-line flexbox, or for // multi-line flexbox with 'align-content: stretch') void SetLineCrossSize(nscoord aLineCrossSize) { mLineCrossSize = aLineCrossSize; } /** * Returns the offset within this line where any baseline-aligned FlexItems * should place their baseline. Usually, this represents a distance from the * line's cross-start edge, but if we're internally reversing the axes (see * AreAxesInternallyReversed()), this instead represents the distance from * its cross-end edge. * * If there are no baseline-aligned FlexItems, returns nscoord_MIN. */ nscoord GetFirstBaselineOffset() const { return mFirstBaselineOffset; } /** * Returns the offset within this line where any last baseline-aligned * FlexItems should place their baseline. Opposite the case of the first * baseline offset, this represents a distance from the line's cross-end * edge (since last baseline-aligned items are flush to the cross-end edge). * If we're internally reversing the axes, this instead represents the * distance from the line's cross-start edge. * * If there are no last baseline-aligned FlexItems, returns nscoord_MIN. */ nscoord GetLastBaselineOffset() const { return mLastBaselineOffset; } // Runs the "Resolving Flexible Lengths" algorithm from section 9.7 of the // CSS flexbox spec to distribute aFlexContainerMainSize among our flex items. void ResolveFlexibleLengths(nscoord aFlexContainerMainSize); void PositionItemsInMainAxis(uint8_t aJustifyContent, nscoord aContentBoxMainSize, const FlexboxAxisTracker& aAxisTracker); void PositionItemsInCrossAxis(nscoord aLineStartPosition, const FlexboxAxisTracker& aAxisTracker); friend class AutoFlexLineListClearer; // (needs access to mItems) private: // Helpers for ResolveFlexibleLengths(): void FreezeItemsEarly(bool aIsUsingFlexGrow); void FreezeOrRestoreEachFlexibleSize(const nscoord aTotalViolation, bool aIsFinalIteration); LinkedList<FlexItem> mItems; // Linked list of this line's flex items. uint32_t mNumItems; // Number of FlexItems in this line (in |mItems|). // (Shouldn't change after GenerateFlexLines finishes // with this line -- at least, not until we add support // for splitting lines across continuations. Then we can // update this count carefully.) // Number of *frozen* FlexItems in this line, based on FlexItem::IsFrozen(). // Mostly used for optimization purposes, e.g. to bail out early from loops // when we can tell they have nothing left to do. uint32_t mNumFrozenItems; nscoord mTotalInnerHypotheticalMainSize; nscoord mTotalOuterHypotheticalMainSize; nscoord mLineCrossSize; nscoord mFirstBaselineOffset; nscoord mLastBaselineOffset; }; // Information about a strut left behind by a FlexItem that's been collapsed // using "visibility:collapse". struct nsFlexContainerFrame::StrutInfo { StrutInfo(uint32_t aItemIdx, nscoord aStrutCrossSize) : mItemIdx(aItemIdx), mStrutCrossSize(aStrutCrossSize) { } uint32_t mItemIdx; // Index in the child list. nscoord mStrutCrossSize; // The cross-size of this strut. }; static void BuildStrutInfoFromCollapsedItems(const FlexLine* aFirstLine, nsTArray<StrutInfo>& aStruts) { MOZ_ASSERT(aFirstLine, "null first line pointer"); MOZ_ASSERT(aStruts.IsEmpty(), "We should only build up StrutInfo once per reflow, so " "aStruts should be empty when this is called"); uint32_t itemIdxInContainer = 0; for (const FlexLine* line = aFirstLine; line; line = line->getNext()) { for (const FlexItem* item = line->GetFirstItem(); item; item = item->getNext()) { if (NS_STYLE_VISIBILITY_COLLAPSE == item->Frame()->StyleVisibility()->mVisible) { // Note the cross size of the line as the item's strut size. aStruts.AppendElement(StrutInfo(itemIdxInContainer, line->GetLineCrossSize())); } itemIdxInContainer++; } } } // Convenience function to get either the "order" or the "box-ordinal-group" // property-value for a flex item (depending on whether the container is a // modern flex container or a legacy box). static int32_t GetOrderOrBoxOrdinalGroup(nsIFrame* aFlexItem, bool aIsLegacyBox) { if (aFlexItem->GetType() == nsGkAtoms::placeholderFrame) { // Always treat placeholders as having the default value, which is // 1 for (legacy) 'box-ordinal-group' and 0 for 'order'. return aIsLegacyBox ? 1 : 0; } if (aIsLegacyBox) { // We'll be using mBoxOrdinal, which has type uint32_t. However, the modern // 'order' property (whose functionality we're co-opting) has type int32_t. // So: if we happen to have a uint32_t value that's greater than INT32_MAX, // we clamp it rather than letting it overflow. Chances are, this is just // an author using BIG_VALUE anyway, so the clamped value should be fine. // (particularly since sufficiently-huge values are busted in Chrome/WebKit // per https://bugs.chromium.org/p/chromium/issues/detail?id=599645 ) uint32_t clampedBoxOrdinal = std::min(aFlexItem->StyleXUL()->mBoxOrdinal, static_cast<uint32_t>(INT32_MAX)); return static_cast<int32_t>(clampedBoxOrdinal); } // Normal case: just use modern 'order' property. return aFlexItem->StylePosition()->mOrder; } // Helper-function to find the first non-anonymous-box descendent of aFrame. static nsIFrame* GetFirstNonAnonBoxDescendant(nsIFrame* aFrame) { while (aFrame) { nsIAtom* pseudoTag = aFrame->StyleContext()->GetPseudo(); // If aFrame isn't an anonymous container, then it'll do. if (!pseudoTag || // No pseudotag. !nsCSSAnonBoxes::IsAnonBox(pseudoTag) || // Pseudotag isn't anon. nsCSSAnonBoxes::IsNonElement(pseudoTag)) { // Text, not a container. break; } // Otherwise, descend to its first child and repeat. // SPECIAL CASE: if we're dealing with an anonymous table, then it might // be wrapping something non-anonymous in its caption or col-group lists // (instead of its principal child list), so we have to look there. // (Note: For anonymous tables that have a non-anon cell *and* a non-anon // column, we'll always return the column. This is fine; we're really just // looking for a handle to *anything* with a meaningful content node inside // the table, for use in DOM comparisons to things outside of the table.) if (MOZ_UNLIKELY(aFrame->GetType() == nsGkAtoms::tableWrapperFrame)) { nsIFrame* captionDescendant = GetFirstNonAnonBoxDescendant(aFrame->GetChildList(kCaptionList).FirstChild()); if (captionDescendant) { return captionDescendant; } } else if (MOZ_UNLIKELY(aFrame->GetType() == nsGkAtoms::tableFrame)) { nsIFrame* colgroupDescendant = GetFirstNonAnonBoxDescendant(aFrame->GetChildList(kColGroupList).FirstChild()); if (colgroupDescendant) { return colgroupDescendant; } } // USUAL CASE: Descend to the first child in principal list. aFrame = aFrame->PrincipalChildList().FirstChild(); } return aFrame; } /** * Sorting helper-function that compares two frames' "order" property-values, * and if they're equal, compares the DOM positions of their corresponding * content nodes. Returns true if aFrame1 is "less than or equal to" aFrame2 * according to this comparison. * * Note: This can't be a static function, because we need to pass it as a * template argument. (Only functions with external linkage can be passed as * template arguments.) * * @return true if the computed "order" property of aFrame1 is less than that * of aFrame2, or if the computed "order" values are equal and aFrame1's * corresponding DOM node is earlier than aFrame2's in the DOM tree. * Otherwise, returns false. */ bool IsOrderLEQWithDOMFallback(nsIFrame* aFrame1, nsIFrame* aFrame2) { MOZ_ASSERT(aFrame1->IsFlexItem() && aFrame2->IsFlexItem(), "this method only intended for comparing flex items"); MOZ_ASSERT(aFrame1->GetParent() == aFrame2->GetParent(), "this method only intended for comparing siblings"); if (aFrame1 == aFrame2) { // Anything is trivially LEQ itself, so we return "true" here... but it's // probably bad if we end up actually needing this, so let's assert. NS_ERROR("Why are we checking if a frame is LEQ itself?"); return true; } const bool isInLegacyBox = IsLegacyBox(aFrame1->GetParent()); int32_t order1 = GetOrderOrBoxOrdinalGroup(aFrame1, isInLegacyBox); int32_t order2 = GetOrderOrBoxOrdinalGroup(aFrame2, isInLegacyBox); if (order1 != order2) { return order1 < order2; } // The "order" values are equal, so we need to fall back on DOM comparison. // For that, we need to dig through any anonymous box wrapper frames to find // the actual frame that corresponds to our child content. aFrame1 = GetFirstNonAnonBoxDescendant(aFrame1); aFrame2 = GetFirstNonAnonBoxDescendant(aFrame2); MOZ_ASSERT(aFrame1 && aFrame2, "why do we have an anonymous box without any " "non-anonymous descendants?"); // Special case: // If either frame is for generated content from ::before or ::after, then // we can't use nsContentUtils::PositionIsBefore(), since that method won't // recognize generated content as being an actual sibling of other nodes. // We know where ::before and ::after nodes *effectively* insert in the DOM // tree, though (at the beginning & end), so we can just special-case them. nsIAtom* pseudo1 = nsPlaceholderFrame::GetRealFrameFor(aFrame1)->StyleContext()->GetPseudo(); nsIAtom* pseudo2 = nsPlaceholderFrame::GetRealFrameFor(aFrame2)->StyleContext()->GetPseudo(); if (pseudo1 == nsCSSPseudoElements::before || pseudo2 == nsCSSPseudoElements::after) { // frame1 is ::before and/or frame2 is ::after => frame1 is LEQ frame2. return true; } if (pseudo1 == nsCSSPseudoElements::after || pseudo2 == nsCSSPseudoElements::before) { // frame1 is ::after and/or frame2 is ::before => frame1 is not LEQ frame2. return false; } // Usual case: Compare DOM position. nsIContent* content1 = aFrame1->GetContent(); nsIContent* content2 = aFrame2->GetContent(); MOZ_ASSERT(content1 != content2, "Two different flex items are using the same nsIContent node for " "comparison, so we may be sorting them in an arbitrary order"); return nsContentUtils::PositionIsBefore(content1, content2); } /** * Sorting helper-function that compares two frames' "order" property-values. * Returns true if aFrame1 is "less than or equal to" aFrame2 according to this * comparison. * * Note: This can't be a static function, because we need to pass it as a * template argument. (Only functions with external linkage can be passed as * template arguments.) * * @return true if the computed "order" property of aFrame1 is less than or * equal to that of aFrame2. Otherwise, returns false. */ bool IsOrderLEQ(nsIFrame* aFrame1, nsIFrame* aFrame2) { MOZ_ASSERT(aFrame1->IsFlexItem() && aFrame2->IsFlexItem(), "this method only intended for comparing flex items"); MOZ_ASSERT(aFrame1->GetParent() == aFrame2->GetParent(), "this method only intended for comparing siblings"); const bool isInLegacyBox = IsLegacyBox(aFrame1->GetParent()); int32_t order1 = GetOrderOrBoxOrdinalGroup(aFrame1, isInLegacyBox); int32_t order2 = GetOrderOrBoxOrdinalGroup(aFrame2, isInLegacyBox); return order1 <= order2; } uint8_t SimplifyAlignOrJustifyContentForOneItem(uint16_t aAlignmentVal, bool aIsAlign) { // Mask away any explicit fallback, to get the main (non-fallback) part of // the specified value: uint16_t specified = aAlignmentVal & NS_STYLE_ALIGN_ALL_BITS; // XXX strip off <overflow-position> bits until we implement it (bug 1311892) specified &= ~NS_STYLE_ALIGN_FLAG_BITS; // FIRST: handle a special-case for "justify-content:stretch" (or equivalent), // which requires that we ignore any author-provided explicit fallback value. if (specified == NS_STYLE_ALIGN_NORMAL) { // In a flex container, *-content: "'normal' behaves as 'stretch'". // Do that conversion early, so it benefits from our 'stretch' special-case. // https://drafts.csswg.org/css-align-3/#distribution-flex specified = NS_STYLE_ALIGN_STRETCH; } if (!aIsAlign && specified == NS_STYLE_ALIGN_STRETCH) { // In a flex container, in "justify-content Axis: [...] 'stretch' behaves // as 'flex-start' (ignoring the specified fallback alignment, if any)." // https://drafts.csswg.org/css-align-3/#distribution-flex // So, we just directly return 'flex-start', & ignore explicit fallback.. return NS_STYLE_ALIGN_FLEX_START; } // Now check for an explicit fallback value (and if it's present, use it). uint16_t explicitFallback = aAlignmentVal >> NS_STYLE_ALIGN_ALL_SHIFT; if (explicitFallback) { // XXX strip off <overflow-position> bits until we implement it // (bug 1311892) explicitFallback &= ~NS_STYLE_ALIGN_FLAG_BITS; return explicitFallback; } // There's no explicit fallback. Use the implied fallback values for // space-{between,around,evenly} (since those values only make sense with // multiple alignment subjects), and otherwise just use the specified value: switch (specified) { case NS_STYLE_ALIGN_SPACE_BETWEEN: return NS_STYLE_ALIGN_START; case NS_STYLE_ALIGN_SPACE_AROUND: case NS_STYLE_ALIGN_SPACE_EVENLY: return NS_STYLE_ALIGN_CENTER; default: return specified; } } uint16_t nsFlexContainerFrame::CSSAlignmentForAbsPosChild( const ReflowInput& aChildRI, LogicalAxis aLogicalAxis) const { WritingMode wm = GetWritingMode(); const FlexboxAxisTracker axisTracker(this, wm, AxisTrackerFlags::eAllowBottomToTopChildOrdering); // If we're row-oriented and the caller is asking about our inline axis (or // alternately, if we're column-oriented and the caller is asking about our // block axis), then the caller is really asking about our *main* axis. // Otherwise, the caller is asking about our cross axis. const bool isMainAxis = (axisTracker.IsRowOriented() == (aLogicalAxis == eLogicalAxisInline)); const nsStylePosition* containerStylePos = StylePosition(); const bool isAxisReversed = isMainAxis ? axisTracker.IsMainAxisReversed() : axisTracker.IsCrossAxisReversed(); uint8_t alignment; if (isMainAxis) { alignment = SimplifyAlignOrJustifyContentForOneItem( containerStylePos->mJustifyContent, /*aIsAlign = */false); } else { const uint8_t alignContent = SimplifyAlignOrJustifyContentForOneItem( containerStylePos->mAlignContent, /*aIsAlign = */true); if (NS_STYLE_FLEX_WRAP_NOWRAP != containerStylePos->mFlexWrap && alignContent != NS_STYLE_ALIGN_STRETCH) { // Multi-line, align-content isn't stretch --> align-content determines // this child's alignment in the cross axis. alignment = alignContent; } else { // Single-line, or multi-line but the (one) line stretches to fill // container. Respect align-self. alignment = aChildRI.mStylePosition->UsedAlignSelf(StyleContext()); // XXX strip off <overflow-position> bits until we implement it // (bug 1311892) alignment &= ~NS_STYLE_ALIGN_FLAG_BITS; if (alignment == NS_STYLE_ALIGN_NORMAL) { // "the 'normal' keyword behaves as 'start' on replaced // absolutely-positioned boxes, and behaves as 'stretch' on all other // absolutely-positioned boxes." // https://drafts.csswg.org/css-align/#align-abspos alignment = aChildRI.mFrame->IsFrameOfType(nsIFrame::eReplaced) ? NS_STYLE_ALIGN_START : NS_STYLE_ALIGN_STRETCH; } } } // Resolve flex-start, flex-end, auto, left, right, baseline, last baseline; if (alignment == NS_STYLE_ALIGN_FLEX_START) { alignment = isAxisReversed ? NS_STYLE_ALIGN_END : NS_STYLE_ALIGN_START; } else if (alignment == NS_STYLE_ALIGN_FLEX_END) { alignment = isAxisReversed ? NS_STYLE_ALIGN_START : NS_STYLE_ALIGN_END; } else if (alignment == NS_STYLE_ALIGN_LEFT || alignment == NS_STYLE_ALIGN_RIGHT) { if (aLogicalAxis == eLogicalAxisInline) { const bool isLeft = (alignment == NS_STYLE_ALIGN_LEFT); alignment = (isLeft == wm.IsBidiLTR()) ? NS_STYLE_ALIGN_START : NS_STYLE_ALIGN_END; } else { alignment = NS_STYLE_ALIGN_START; } } else if (alignment == NS_STYLE_ALIGN_BASELINE) { alignment = NS_STYLE_ALIGN_START; } else if (alignment == NS_STYLE_ALIGN_LAST_BASELINE) { alignment = NS_STYLE_ALIGN_END; } return alignment; } bool nsFlexContainerFrame::IsHorizontal() { const FlexboxAxisTracker axisTracker(this, GetWritingMode()); return axisTracker.IsMainAxisHorizontal(); } UniquePtr<FlexItem> nsFlexContainerFrame::GenerateFlexItemForChild( nsPresContext* aPresContext, nsIFrame* aChildFrame, const ReflowInput& aParentReflowInput, const FlexboxAxisTracker& aAxisTracker) { // Create temporary reflow state just for sizing -- to get hypothetical // main-size and the computed values of min / max main-size property. // (This reflow state will _not_ be used for reflow.) ReflowInput childRI(aPresContext, aParentReflowInput, aChildFrame, aParentReflowInput.ComputedSize(aChildFrame->GetWritingMode())); // FLEX GROW & SHRINK WEIGHTS // -------------------------- float flexGrow, flexShrink; if (IsLegacyBox(this)) { flexGrow = flexShrink = aChildFrame->StyleXUL()->mBoxFlex; } else { const nsStylePosition* stylePos = aChildFrame->StylePosition(); flexGrow = stylePos->mFlexGrow; flexShrink = stylePos->mFlexShrink; } WritingMode childWM = childRI.GetWritingMode(); // MAIN SIZES (flex base size, min/max size) // ----------------------------------------- nscoord flexBaseSize = GET_MAIN_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedISize(), childRI.ComputedBSize()); nscoord mainMinSize = GET_MAIN_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedMinISize(), childRI.ComputedMinBSize()); nscoord mainMaxSize = GET_MAIN_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedMaxISize(), childRI.ComputedMaxBSize()); // This is enforced by the ReflowInput where these values come from: MOZ_ASSERT(mainMinSize <= mainMaxSize, "min size is larger than max size"); // CROSS SIZES (tentative cross size, min/max cross size) // ------------------------------------------------------ // Grab the cross size from the reflow state. This might be the right value, // or we might resolve it to something else in SizeItemInCrossAxis(); hence, // it's tentative. See comment under "Cross Size Determination" for more. nscoord tentativeCrossSize = GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedISize(), childRI.ComputedBSize()); nscoord crossMinSize = GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedMinISize(), childRI.ComputedMinBSize()); nscoord crossMaxSize = GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, childWM, childRI.ComputedMaxISize(), childRI.ComputedMaxBSize()); // SPECIAL-CASE FOR WIDGET-IMPOSED SIZES // Check if we're a themed widget, in which case we might have a minimum // main & cross size imposed by our widget (which we can't go below), or // (more severe) our widget might have only a single valid size. bool isFixedSizeWidget = false; const nsStyleDisplay* disp = aChildFrame->StyleDisplay(); if (aChildFrame->IsThemed(disp)) { LayoutDeviceIntSize widgetMinSize; bool canOverride = true; aPresContext->GetTheme()-> GetMinimumWidgetSize(aPresContext, aChildFrame, disp->mAppearance, &widgetMinSize, &canOverride); nscoord widgetMainMinSize = aPresContext->DevPixelsToAppUnits( aAxisTracker.GetMainComponent(widgetMinSize)); nscoord widgetCrossMinSize = aPresContext->DevPixelsToAppUnits( aAxisTracker.GetCrossComponent(widgetMinSize)); // GMWS() returns border-box. We need content-box, so subtract // borderPadding (but don't let that push our min sizes below 0). nsMargin& bp = childRI.ComputedPhysicalBorderPadding(); widgetMainMinSize = std::max(widgetMainMinSize - aAxisTracker.GetMarginSizeInMainAxis(bp), 0); widgetCrossMinSize = std::max(widgetCrossMinSize - aAxisTracker.GetMarginSizeInCrossAxis(bp), 0); if (!canOverride) { // Fixed-size widget: freeze our main-size at the widget's mandated size. // (Set min and max main-sizes to that size, too, to keep us from // clamping to any other size later on.) flexBaseSize = mainMinSize = mainMaxSize = widgetMainMinSize; tentativeCrossSize = crossMinSize = crossMaxSize = widgetCrossMinSize; isFixedSizeWidget = true; } else { // Variable-size widget: ensure our min/max sizes are at least as large // as the widget's mandated minimum size, so we don't flex below that. mainMinSize = std::max(mainMinSize, widgetMainMinSize); mainMaxSize = std::max(mainMaxSize, widgetMainMinSize); if (tentativeCrossSize != NS_INTRINSICSIZE) { tentativeCrossSize = std::max(tentativeCrossSize, widgetCrossMinSize); } crossMinSize = std::max(crossMinSize, widgetCrossMinSize); crossMaxSize = std::max(crossMaxSize, widgetCrossMinSize); } } // Construct the flex item! auto item = MakeUnique<FlexItem>(childRI, flexGrow, flexShrink, flexBaseSize, mainMinSize, mainMaxSize, tentativeCrossSize, crossMinSize, crossMaxSize, aAxisTracker); // If we're inflexible, we can just freeze to our hypothetical main-size // up-front. Similarly, if we're a fixed-size widget, we only have one // valid size, so we freeze to keep ourselves from flexing. if (isFixedSizeWidget || (flexGrow == 0.0f && flexShrink == 0.0f)) { item->Freeze(); } // Resolve "flex-basis:auto" and/or "min-[width|height]:auto" (which might // require us to reflow the item to measure content height) ResolveAutoFlexBasisAndMinSize(aPresContext, *item, childRI, aAxisTracker); return item; } // Static helper-functions for ResolveAutoFlexBasisAndMinSize(): // ------------------------------------------------------------- // Indicates whether the cross-size property is set to something definite. // The logic here should be similar to the logic for isAutoWidth/isAutoHeight // in nsFrame::ComputeSizeWithIntrinsicDimensions(). static bool IsCrossSizeDefinite(const ReflowInput& aItemReflowInput, const FlexboxAxisTracker& aAxisTracker) { const nsStylePosition* pos = aItemReflowInput.mStylePosition; if (aAxisTracker.IsCrossAxisHorizontal()) { return pos->mWidth.GetUnit() != eStyleUnit_Auto; } // else, vertical. (We need to use IsAutoHeight() to catch e.g. %-height // applied to indefinite-height containing block, which counts as auto.) nscoord cbHeight = aItemReflowInput.mCBReflowInput->ComputedHeight(); return !nsLayoutUtils::IsAutoHeight(pos->mHeight, cbHeight); } // If aFlexItem has a definite cross size, this function returns it, for usage // (in combination with an intrinsic ratio) for resolving the item's main size // or main min-size. // // The parameter "aMinSizeFallback" indicates whether we should fall back to // returning the cross min-size, when the cross size is indefinite. (This param // should be set IFF the caller intends to resolve the main min-size.) If this // param is true, then this function is guaranteed to return a definite value // (i.e. not NS_AUTOHEIGHT, excluding cases where huge sizes are involved). // // XXXdholbert the min-size behavior here is based on my understanding in // http://lists.w3.org/Archives/Public/www-style/2014Jul/0053.html // If my understanding there ends up being wrong, we'll need to update this. static nscoord CrossSizeToUseWithRatio(const FlexItem& aFlexItem, const ReflowInput& aItemReflowInput, bool aMinSizeFallback, const FlexboxAxisTracker& aAxisTracker) { if (aFlexItem.IsStretched()) { // Definite cross-size, imposed via 'align-self:stretch' & flex container. return aFlexItem.GetCrossSize(); } if (IsCrossSizeDefinite(aItemReflowInput, aAxisTracker)) { // Definite cross size. return GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, aFlexItem.GetWritingMode(), aItemReflowInput.ComputedISize(), aItemReflowInput.ComputedBSize()); } if (aMinSizeFallback) { // Indefinite cross-size, and we're resolving main min-size, so we'll fall // back to ussing the cross min-size (which should be definite). return GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, aFlexItem.GetWritingMode(), aItemReflowInput.ComputedMinISize(), aItemReflowInput.ComputedMinBSize()); } // Indefinite cross-size. return NS_AUTOHEIGHT; } // Convenience function; returns a main-size, given a cross-size and an // intrinsic ratio. The intrinsic ratio must not have 0 in its cross-axis // component (or else we'll divide by 0). static nscoord MainSizeFromAspectRatio(nscoord aCrossSize, const nsSize& aIntrinsicRatio, const FlexboxAxisTracker& aAxisTracker) { MOZ_ASSERT(aAxisTracker.GetCrossComponent(aIntrinsicRatio) != 0, "Invalid ratio; will divide by 0! Caller should've checked..."); if (aAxisTracker.IsCrossAxisHorizontal()) { // cross axis horiz --> aCrossSize is a width. Converting to height. return NSCoordMulDiv(aCrossSize, aIntrinsicRatio.height, aIntrinsicRatio.width); } // cross axis vert --> aCrossSize is a height. Converting to width. return NSCoordMulDiv(aCrossSize, aIntrinsicRatio.width, aIntrinsicRatio.height); } // Partially resolves "min-[width|height]:auto" and returns the resulting value. // By "partially", I mean we don't consider the min-content size (but we do // consider flex-basis, main max-size, and the intrinsic aspect ratio). // The caller is responsible for computing & considering the min-content size // in combination with the partially-resolved value that this function returns. // // Spec reference: http://dev.w3.org/csswg/css-flexbox/#min-size-auto static nscoord PartiallyResolveAutoMinSize(const FlexItem& aFlexItem, const ReflowInput& aItemReflowInput, const FlexboxAxisTracker& aAxisTracker) { MOZ_ASSERT(aFlexItem.NeedsMinSizeAutoResolution(), "only call for FlexItems that need min-size auto resolution"); nscoord minMainSize = nscoord_MAX; // Intentionally huge; we'll shrink it // from here, w/ std::min(). // We need the smallest of: // * the used flex-basis, if the computed flex-basis was 'auto': // XXXdholbert ('auto' might be renamed to 'main-size'; see bug 1032922) if (eStyleUnit_Auto == aItemReflowInput.mStylePosition->mFlexBasis.GetUnit() && aFlexItem.GetFlexBaseSize() != NS_AUTOHEIGHT) { // NOTE: We skip this if the flex base size depends on content & isn't yet // resolved. This is OK, because the caller is responsible for computing // the min-content height and min()'ing it with the value we return, which // is equivalent to what would happen if we min()'d that at this point. minMainSize = std::min(minMainSize, aFlexItem.GetFlexBaseSize()); } // * the computed max-width (max-height), if that value is definite: nscoord maxSize = GET_MAIN_COMPONENT_LOGICAL(aAxisTracker, aFlexItem.GetWritingMode(), aItemReflowInput.ComputedMaxISize(), aItemReflowInput.ComputedMaxBSize()); if (maxSize != NS_UNCONSTRAINEDSIZE) { minMainSize = std::min(minMainSize, maxSize); } // * if the item has no intrinsic aspect ratio, its min-content size: // --- SKIPPING THIS IN THIS FUNCTION --- caller's responsibility. // * if the item has an intrinsic aspect ratio, the width (height) calculated // from the aspect ratio and any definite size constraints in the opposite // dimension. if (aAxisTracker.GetCrossComponent(aFlexItem.IntrinsicRatio()) != 0) { // We have a usable aspect ratio. (not going to divide by 0) const bool useMinSizeIfCrossSizeIsIndefinite = true; nscoord crossSizeToUseWithRatio = CrossSizeToUseWithRatio(aFlexItem, aItemReflowInput, useMinSizeIfCrossSizeIsIndefinite, aAxisTracker); nscoord minMainSizeFromRatio = MainSizeFromAspectRatio(crossSizeToUseWithRatio, aFlexItem.IntrinsicRatio(), aAxisTracker); minMainSize = std::min(minMainSize, minMainSizeFromRatio); } return minMainSize; } // Resolves flex-basis:auto, using the given intrinsic ratio and the flex // item's cross size. On success, updates the flex item with its resolved // flex-basis and returns true. On failure (e.g. if the ratio is invalid or // the cross-size is indefinite), returns false. static bool ResolveAutoFlexBasisFromRatio(FlexItem& aFlexItem, const ReflowInput& aItemReflowInput, const FlexboxAxisTracker& aAxisTracker) { MOZ_ASSERT(NS_AUTOHEIGHT == aFlexItem.GetFlexBaseSize(), "Should only be called to resolve an 'auto' flex-basis"); // If the flex item has ... // - an intrinsic aspect ratio, // - a [used] flex-basis of 'main-size' [auto?] [We have this, if we're here.] // - a definite cross size // then the flex base size is calculated from its inner cross size and the // flex item’s intrinsic aspect ratio. if (aAxisTracker.GetCrossComponent(aFlexItem.IntrinsicRatio()) != 0) { // We have a usable aspect ratio. (not going to divide by 0) const bool useMinSizeIfCrossSizeIsIndefinite = false; nscoord crossSizeToUseWithRatio = CrossSizeToUseWithRatio(aFlexItem, aItemReflowInput, useMinSizeIfCrossSizeIsIndefinite, aAxisTracker); if (crossSizeToUseWithRatio != NS_AUTOHEIGHT) { // We have a definite cross-size nscoord mainSizeFromRatio = MainSizeFromAspectRatio(crossSizeToUseWithRatio, aFlexItem.IntrinsicRatio(), aAxisTracker); aFlexItem.SetFlexBaseSizeAndMainSize(mainSizeFromRatio); return true; } } return false; } // Note: If & when we handle "min-height: min-content" for flex items, // we may want to resolve that in this function, too. void nsFlexContainerFrame:: ResolveAutoFlexBasisAndMinSize(nsPresContext* aPresContext, FlexItem& aFlexItem, const ReflowInput& aItemReflowInput, const FlexboxAxisTracker& aAxisTracker) { // (Note: We should never have a used flex-basis of "auto" if our main axis // is horizontal; width values should always be resolvable without reflow.) const bool isMainSizeAuto = (!aAxisTracker.IsMainAxisHorizontal() && NS_AUTOHEIGHT == aFlexItem.GetFlexBaseSize()); const bool isMainMinSizeAuto = aFlexItem.NeedsMinSizeAutoResolution(); if (!isMainSizeAuto && !isMainMinSizeAuto) { // Nothing to do; this function is only needed for flex items // with a used flex-basis of "auto" or a min-main-size of "auto". return; } // We may be about to do computations based on our item's cross-size // (e.g. using it as a contstraint when measuring our content in the // main axis, or using it with the intrinsic ratio to obtain a main size). // BEFORE WE DO THAT, we need let the item "pre-stretch" its cross size (if // it's got 'align-self:stretch'), for a certain case where the spec says // the stretched cross size is considered "definite". That case is if we // have a single-line (nowrap) flex container which itself has a definite // cross-size. Otherwise, we'll wait to do stretching, since (in other // cases) we don't know how much the item should stretch yet. const ReflowInput* flexContainerRI = aItemReflowInput.mParentReflowInput; MOZ_ASSERT(flexContainerRI, "flex item's reflow state should have ptr to container's state"); if (NS_STYLE_FLEX_WRAP_NOWRAP == flexContainerRI->mStylePosition->mFlexWrap) { // XXXdholbert Maybe this should share logic with ComputeCrossSize()... // Alternately, maybe tentative container cross size should be passed down. nscoord containerCrossSize = GET_CROSS_COMPONENT_LOGICAL(aAxisTracker, aAxisTracker.GetWritingMode(), flexContainerRI->ComputedISize(), flexContainerRI->ComputedBSize()); // Is container's cross size "definite"? // (Container's cross size is definite if cross-axis is horizontal, or if // cross-axis is vertical and the cross-size is not NS_AUTOHEIGHT.) if (aAxisTracker.IsCrossAxisHorizontal() || containerCrossSize != NS_AUTOHEIGHT) { aFlexItem.ResolveStretchedCrossSize(containerCrossSize, aAxisTracker); } } nscoord resolvedMinSize; // (only set/used if isMainMinSizeAuto==true) bool minSizeNeedsToMeasureContent = false; // assume the best if (isMainMinSizeAuto) { // Resolve the min-size, except for considering the min-content size. // (We'll consider that later, if we need to.) resolvedMinSize = PartiallyResolveAutoMinSize(aFlexItem, aItemReflowInput, aAxisTracker); if (resolvedMinSize > 0 && aAxisTracker.GetCrossComponent(aFlexItem.IntrinsicRatio()) == 0) { // We don't have a usable aspect ratio, so we need to consider our // min-content size as another candidate min-size, which we'll have to // min() with the current resolvedMinSize. // (If resolvedMinSize were already at 0, we could skip this measurement // because it can't go any lower. But it's not 0, so we need it.) minSizeNeedsToMeasureContent = true; } } bool flexBasisNeedsToMeasureContent = false; // assume the best if (isMainSizeAuto) { if (!ResolveAutoFlexBasisFromRatio(aFlexItem, aItemReflowInput, aAxisTracker)) { flexBasisNeedsToMeasureContent = true; } } // Measure content, if needed (w/ intrinsic-width method or a reflow) if (minSizeNeedsToMeasureContent || flexBasisNeedsToMeasureContent) { if (aAxisTracker.IsMainAxisHorizontal()) { if (minSizeNeedsToMeasureContent) { nscoord frameMinISize = aFlexItem.Frame()->GetMinISize(aItemReflowInput.mRenderingContext); resolvedMinSize = std::min(resolvedMinSize, frameMinISize); } NS_ASSERTION(!flexBasisNeedsToMeasureContent, "flex-basis:auto should have been resolved in the " "reflow state, for horizontal flexbox. It shouldn't need " "special handling here"); } else { // If this item is flexible (vertically), or if we're measuring the // 'auto' min-height and our main-size is something else, then we assume // that the computed-height we're reflowing with now could be different // from the one we'll use for this flex item's "actual" reflow later on. // In that case, we need to be sure the flex item treats this as a // vertical resize, even though none of its ancestors are necessarily // being vertically resized. // (Note: We don't have to do this for width, because InitResizeFlags // will always turn on mHResize on when it sees that the computed width // is different from current width, and that's all we need.) bool forceVerticalResizeForMeasuringReflow = !aFlexItem.IsFrozen() || // Is the item flexible? !flexBasisNeedsToMeasureContent; // Are we *only* measuring it for // 'min-height:auto'? nscoord contentHeight = MeasureFlexItemContentHeight(aPresContext, aFlexItem, forceVerticalResizeForMeasuringReflow, *flexContainerRI); if (minSizeNeedsToMeasureContent) { resolvedMinSize = std::min(resolvedMinSize, contentHeight); } if (flexBasisNeedsToMeasureContent) { aFlexItem.SetFlexBaseSizeAndMainSize(contentHeight); } } } if (isMainMinSizeAuto) { aFlexItem.UpdateMainMinSize(resolvedMinSize); } } nscoord nsFlexContainerFrame:: MeasureFlexItemContentHeight(nsPresContext* aPresContext, FlexItem& aFlexItem, bool aForceVerticalResizeForMeasuringReflow, const ReflowInput& aParentReflowInput) { // Set up a reflow state for measuring the flex item's auto-height: WritingMode wm = aFlexItem.Frame()->GetWritingMode(); LogicalSize availSize = aParentReflowInput.ComputedSize(wm); availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE; ReflowInput childRIForMeasuringHeight(aPresContext, aParentReflowInput, aFlexItem.Frame(), availSize, nullptr, ReflowInput::CALLER_WILL_INIT); childRIForMeasuringHeight.mFlags.mIsFlexContainerMeasuringHeight = true; childRIForMeasuringHeight.Init(aPresContext); if (aFlexItem.IsStretched()) { childRIForMeasuringHeight.SetComputedWidth(aFlexItem.GetCrossSize()); childRIForMeasuringHeight.SetHResize(true); } if (aForceVerticalResizeForMeasuringReflow) { childRIForMeasuringHeight.SetVResize(true); } ReflowOutput childDesiredSize(childRIForMeasuringHeight); nsReflowStatus childReflowStatus; const uint32_t flags = NS_FRAME_NO_MOVE_FRAME; ReflowChild(aFlexItem.Frame(), aPresContext, childDesiredSize, childRIForMeasuringHeight, 0, 0, flags, childReflowStatus); MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus), "We gave flex item unconstrained available height, so it " "should be complete"); FinishReflowChild(aFlexItem.Frame(), aPresContext, childDesiredSize, &childRIForMeasuringHeight, 0, 0, flags); aFlexItem.SetHadMeasuringReflow(); aFlexItem.SetAscent(childDesiredSize.BlockStartAscent()); // Subtract border/padding in vertical axis, to get _just_ // the effective computed value of the "height" property. nscoord childDesiredHeight = childDesiredSize.Height() - childRIForMeasuringHeight.ComputedPhysicalBorderPadding().TopBottom(); return std::max(0, childDesiredHeight); } FlexItem::FlexItem(ReflowInput& aFlexItemReflowInput, float aFlexGrow, float aFlexShrink, nscoord aFlexBaseSize, nscoord aMainMinSize, nscoord aMainMaxSize, nscoord aTentativeCrossSize, nscoord aCrossMinSize, nscoord aCrossMaxSize, const FlexboxAxisTracker& aAxisTracker) : mFrame(aFlexItemReflowInput.mFrame), mFlexGrow(aFlexGrow), mFlexShrink(aFlexShrink), mIntrinsicRatio(mFrame->GetIntrinsicRatio()), mBorderPadding(aFlexItemReflowInput.ComputedPhysicalBorderPadding()), mMargin(aFlexItemReflowInput.ComputedPhysicalMargin()), mMainMinSize(aMainMinSize), mMainMaxSize(aMainMaxSize), mCrossMinSize(aCrossMinSize), mCrossMaxSize(aCrossMaxSize), mMainPosn(0), mCrossSize(aTentativeCrossSize), mCrossPosn(0), mAscent(0), mShareOfWeightSoFar(0.0f), mIsFrozen(false), mHadMinViolation(false), mHadMaxViolation(false), mHadMeasuringReflow(false), mIsStretched(false), mIsStrut(false), // mNeedsMinSizeAutoResolution is initialized in CheckForMinSizeAuto() mWM(aFlexItemReflowInput.GetWritingMode()) // mAlignSelf, see below { MOZ_ASSERT(mFrame, "expecting a non-null child frame"); MOZ_ASSERT(mFrame->GetType() != nsGkAtoms::placeholderFrame, "placeholder frames should not be treated as flex items"); MOZ_ASSERT(!(mFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW), "out-of-flow frames should not be treated as flex items"); const ReflowInput* containerRS = aFlexItemReflowInput.mParentReflowInput; if (IsLegacyBox(containerRS->mFrame)) { // For -webkit-box/-webkit-inline-box, we need to: // (1) Use "-webkit-box-align" instead of "align-items" to determine the // container's cross-axis alignment behavior. // (2) Suppress the ability for flex items to override that with their own // cross-axis alignment. (The legacy box model doesn't support this.) // So, each FlexItem simply copies the container's converted "align-items" // value and disregards their own "align-self" property. const nsStyleXUL* containerStyleXUL = containerRS->mFrame->StyleXUL(); mAlignSelf = ConvertLegacyStyleToAlignItems(containerStyleXUL); } else { mAlignSelf = aFlexItemReflowInput.mStylePosition->UsedAlignSelf( containerRS->mFrame->StyleContext()); if (MOZ_LIKELY(mAlignSelf == NS_STYLE_ALIGN_NORMAL)) { mAlignSelf = NS_STYLE_ALIGN_STRETCH; } // XXX strip off the <overflow-position> bit until we implement that mAlignSelf &= ~NS_STYLE_ALIGN_FLAG_BITS; } SetFlexBaseSizeAndMainSize(aFlexBaseSize); CheckForMinSizeAuto(aFlexItemReflowInput, aAxisTracker); // Assert that any "auto" margin components are set to 0. // (We'll resolve them later; until then, we want to treat them as 0-sized.) #ifdef DEBUG { const nsStyleSides& styleMargin = aFlexItemReflowInput.mStyleMargin->mMargin; NS_FOR_CSS_SIDES(side) { if (styleMargin.GetUnit(side) == eStyleUnit_Auto) { MOZ_ASSERT(GetMarginComponentForSide(side) == 0, "Someone else tried to resolve our auto margin"); } } } #endif // DEBUG // Map align-self 'baseline' value to 'start' when baseline alignment // is not possible because the FlexItem's writing mode is orthogonal to // the main axis of the container. If that's the case, we just directly // convert our align-self value here, so that we don't have to handle this // with special cases elsewhere. // We are treating this case as one where it is appropriate to use the // fallback values defined at https://www.w3.org/TR/css-align-3/#baseline if (aAxisTracker.IsRowOriented() == aAxisTracker.GetWritingMode().IsOrthogonalTo(mWM)) { if (mAlignSelf == NS_STYLE_ALIGN_BASELINE) { mAlignSelf = NS_STYLE_ALIGN_FLEX_START; } else if (mAlignSelf == NS_STYLE_ALIGN_LAST_BASELINE) { mAlignSelf = NS_STYLE_ALIGN_FLEX_END; } } } // Simplified constructor for creating a special "strut" FlexItem, for a child // with visibility:collapse. The strut has 0 main-size, and it only exists to // impose a minimum cross size on whichever FlexLine it ends up in. FlexItem::FlexItem(nsIFrame* aChildFrame, nscoord aCrossSize, WritingMode aContainerWM) : mFrame(aChildFrame), mFlexGrow(0.0f), mFlexShrink(0.0f), mIntrinsicRatio(), // mBorderPadding uses default constructor, // mMargin uses default constructor, mFlexBaseSize(0), mMainMinSize(0), mMainMaxSize(0), mCrossMinSize(0), mCrossMaxSize(0), mMainSize(0), mMainPosn(0), mCrossSize(aCrossSize), mCrossPosn(0), mAscent(0), mShareOfWeightSoFar(0.0f), mIsFrozen(true), mHadMinViolation(false), mHadMaxViolation(false), mHadMeasuringReflow(false), mIsStretched(false), mIsStrut(true), // (this is the constructor for making struts, after all) mNeedsMinSizeAutoResolution(false), mWM(aContainerWM), mAlignSelf(NS_STYLE_ALIGN_FLEX_START) { MOZ_ASSERT(mFrame, "expecting a non-null child frame"); MOZ_ASSERT(NS_STYLE_VISIBILITY_COLLAPSE == mFrame->StyleVisibility()->mVisible, "Should only make struts for children with 'visibility:collapse'"); MOZ_ASSERT(mFrame->GetType() != nsGkAtoms::placeholderFrame, "placeholder frames should not be treated as flex items"); MOZ_ASSERT(!(mFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW), "out-of-flow frames should not be treated as flex items"); } void FlexItem::CheckForMinSizeAuto(const ReflowInput& aFlexItemReflowInput, const FlexboxAxisTracker& aAxisTracker) { const nsStylePosition* pos = aFlexItemReflowInput.mStylePosition; const nsStyleDisplay* disp = aFlexItemReflowInput.mStyleDisplay; // We'll need special behavior for "min-[width|height]:auto" (whichever is in // the main axis) iff: // (a) its computed value is "auto" // (b) the "overflow" sub-property in the same axis (the main axis) has a // computed value of "visible" const nsStyleCoord& minSize = GET_MAIN_COMPONENT(aAxisTracker, pos->mMinWidth, pos->mMinHeight); const uint8_t overflowVal = GET_MAIN_COMPONENT(aAxisTracker, disp->mOverflowX, disp->mOverflowY); mNeedsMinSizeAutoResolution = (minSize.GetUnit() == eStyleUnit_Auto && overflowVal == NS_STYLE_OVERFLOW_VISIBLE); } nscoord FlexItem::GetBaselineOffsetFromOuterCrossEdge( AxisEdgeType aEdge, const FlexboxAxisTracker& aAxisTracker, bool aUseFirstLineBaseline) const { // NOTE: Currently, 'mAscent' (taken from reflow) is an inherently vertical // measurement -- it's the distance from the border-top edge of this FlexItem // to its baseline. So, we can really only do baseline alignment when the // cross axis is vertical. (The FlexItem constructor enforces this when // resolving the item's "mAlignSelf" value). MOZ_ASSERT(!aAxisTracker.IsCrossAxisHorizontal(), "Only expecting to be doing baseline computations when the " "cross axis is vertical"); AxisOrientationType crossAxis = aAxisTracker.GetCrossAxis(); mozilla::Side sideToMeasureFrom = kAxisOrientationToSidesMap[crossAxis][aEdge]; nscoord marginTopToBaseline = ResolvedAscent(aUseFirstLineBaseline) + mMargin.top; if (sideToMeasureFrom == eSideTop) { // Measuring from top (normal case): the distance from the margin-box top // edge to the baseline is just ascent + margin-top. return marginTopToBaseline; } MOZ_ASSERT(sideToMeasureFrom == eSideBottom, "We already checked that we're dealing with a vertical axis, and " "we're not using the top side, so that only leaves the bottom..."); // Measuring from bottom: The distance from the margin-box bottom edge to the // baseline is just the margin-box cross size (i.e. outer cross size), minus // the already-computed distance from margin-top to baseline. return GetOuterCrossSize(crossAxis) - marginTopToBaseline; } uint32_t FlexItem::GetNumAutoMarginsInAxis(AxisOrientationType aAxis) const { uint32_t numAutoMargins = 0; const nsStyleSides& styleMargin = mFrame->StyleMargin()->mMargin; for (uint32_t i = 0; i < eNumAxisEdges; i++) { mozilla::Side side = kAxisOrientationToSidesMap[aAxis][i]; if (styleMargin.GetUnit(side) == eStyleUnit_Auto) { numAutoMargins++; } } // Mostly for clarity: MOZ_ASSERT(numAutoMargins <= 2, "We're just looking at one item along one dimension, so we " "should only have examined 2 margins"); return numAutoMargins; } bool FlexItem::CanMainSizeInfluenceCrossSize( const FlexboxAxisTracker& aAxisTracker) const { if (mIsStretched) { // We've already had our cross-size stretched for "align-self:stretch"). // The container is imposing its cross size on us. return false; } if (mIsStrut) { // Struts (for visibility:collapse items) have a predetermined size; // no need to measure anything. return false; } if (HasIntrinsicRatio()) { // For flex items that have an intrinsic ratio (and maintain it, i.e. are // not stretched, which we already checked above): changes to main-size // *do* influence the cross size. return true; } if (aAxisTracker.IsCrossAxisHorizontal()) { // If the cross axis is horizontal, then changes to the item's main size // (height) can't influence its cross size (width), if the item is a block // with a horizontal writing-mode. // XXXdholbert This doesn't account for vertical writing-modes, items with // aspect ratios, items that are multicol elements, & items that are // multi-line vertical flex containers. In all of those cases, a change to // the height could influence the width. return false; } // Default assumption, if we haven't proven otherwise: the resolved main size // *can* change the cross size. return true; } // Keeps track of our position along a particular axis (where a '0' position // corresponds to the 'start' edge of that axis). // This class shouldn't be instantiated directly -- rather, it should only be // instantiated via its subclasses defined below. class MOZ_STACK_CLASS PositionTracker { public: // Accessor for the current value of the position that we're tracking. inline nscoord GetPosition() const { return mPosition; } inline AxisOrientationType GetAxis() const { return mAxis; } // Advances our position across the start edge of the given margin, in the // axis we're tracking. void EnterMargin(const nsMargin& aMargin) { mozilla::Side side = kAxisOrientationToSidesMap[mAxis][eAxisEdge_Start]; mPosition += aMargin.Side(side); } // Advances our position across the end edge of the given margin, in the axis // we're tracking. void ExitMargin(const nsMargin& aMargin) { mozilla::Side side = kAxisOrientationToSidesMap[mAxis][eAxisEdge_End]; mPosition += aMargin.Side(side); } // Advances our current position from the start side of a child frame's // border-box to the frame's upper or left edge (depending on our axis). // (Note that this is a no-op if our axis grows in the same direction as // the corresponding logical axis.) void EnterChildFrame(nscoord aChildFrameSize) { if (mIsAxisReversed) { mPosition += aChildFrameSize; } } // Advances our current position from a frame's upper or left border-box edge // (whichever is in the axis we're tracking) to the 'end' side of the frame // in the axis that we're tracking. (Note that this is a no-op if our axis // is reversed with respect to the corresponding logical axis.) void ExitChildFrame(nscoord aChildFrameSize) { if (!mIsAxisReversed) { mPosition += aChildFrameSize; } } protected: // Protected constructor, to be sure we're only instantiated via a subclass. PositionTracker(AxisOrientationType aAxis, bool aIsAxisReversed) : mPosition(0), mAxis(aAxis), mIsAxisReversed(aIsAxisReversed) {} // Delete copy-constructor & reassignment operator, to prevent accidental // (unnecessary) copying. PositionTracker(const PositionTracker&) = delete; PositionTracker& operator=(const PositionTracker&) = delete; // Member data: nscoord mPosition; // The position we're tracking // XXXdholbert [BEGIN DEPRECATED] const AxisOrientationType mAxis; // The axis along which we're moving. // XXXdholbert [END DEPRECATED] const bool mIsAxisReversed; // Is the axis along which we're moving reversed // (e.g. LTR vs RTL) with respect to the // corresponding axis on the flex container's WM? }; // Tracks our position in the main axis, when we're laying out flex items. // The "0" position represents the main-start edge of the flex container's // content-box. class MOZ_STACK_CLASS MainAxisPositionTracker : public PositionTracker { public: MainAxisPositionTracker(const FlexboxAxisTracker& aAxisTracker, const FlexLine* aLine, uint8_t aJustifyContent, nscoord aContentBoxMainSize); ~MainAxisPositionTracker() { MOZ_ASSERT(mNumPackingSpacesRemaining == 0, "miscounted the number of packing spaces"); MOZ_ASSERT(mNumAutoMarginsInMainAxis == 0, "miscounted the number of auto margins"); } // Advances past the packing space (if any) between two flex items void TraversePackingSpace(); // If aItem has any 'auto' margins in the main axis, this method updates the // corresponding values in its margin. void ResolveAutoMarginsInMainAxis(FlexItem& aItem); private: nscoord mPackingSpaceRemaining; uint32_t mNumAutoMarginsInMainAxis; uint32_t mNumPackingSpacesRemaining; // XXX this should be uint16_t when we add explicit fallback handling uint8_t mJustifyContent; }; // Utility class for managing our position along the cross axis along // the whole flex container (at a higher level than a single line). // The "0" position represents the cross-start edge of the flex container's // content-box. class MOZ_STACK_CLASS CrossAxisPositionTracker : public PositionTracker { public: CrossAxisPositionTracker(FlexLine* aFirstLine, const ReflowInput& aReflowInput, nscoord aContentBoxCrossSize, bool aIsCrossSizeDefinite, const FlexboxAxisTracker& aAxisTracker); // Advances past the packing space (if any) between two flex lines void TraversePackingSpace(); // Advances past the given FlexLine void TraverseLine(FlexLine& aLine) { mPosition += aLine.GetLineCrossSize(); } private: // Redeclare the frame-related methods from PositionTracker as private with // = delete, to be sure (at compile time) that no client code can invoke // them. (Unlike the other PositionTracker derived classes, this class here // deals with FlexLines, not with individual FlexItems or frames.) void EnterMargin(const nsMargin& aMargin) = delete; void ExitMargin(const nsMargin& aMargin) = delete; void EnterChildFrame(nscoord aChildFrameSize) = delete; void ExitChildFrame(nscoord aChildFrameSize) = delete; nscoord mPackingSpaceRemaining; uint32_t mNumPackingSpacesRemaining; // XXX this should be uint16_t when we add explicit fallback handling uint8_t mAlignContent; }; // Utility class for managing our position along the cross axis, *within* a // single flex line. class MOZ_STACK_CLASS SingleLineCrossAxisPositionTracker : public PositionTracker { public: explicit SingleLineCrossAxisPositionTracker(const FlexboxAxisTracker& aAxisTracker); void ResolveAutoMarginsInCrossAxis(const FlexLine& aLine, FlexItem& aItem); void EnterAlignPackingSpace(const FlexLine& aLine, const FlexItem& aItem, const FlexboxAxisTracker& aAxisTracker); // Resets our position to the cross-start edge of this line. inline void ResetPosition() { mPosition = 0; } }; //---------------------------------------------------------------------- // Frame class boilerplate // ======================= NS_QUERYFRAME_HEAD(nsFlexContainerFrame) NS_QUERYFRAME_ENTRY(nsFlexContainerFrame) NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame) NS_IMPL_FRAMEARENA_HELPERS(nsFlexContainerFrame) nsContainerFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell, nsStyleContext* aContext) { return new (aPresShell) nsFlexContainerFrame(aContext); } //---------------------------------------------------------------------- // nsFlexContainerFrame Method Implementations // =========================================== /* virtual */ nsFlexContainerFrame::~nsFlexContainerFrame() { } /* virtual */ void nsFlexContainerFrame::Init(nsIContent* aContent, nsContainerFrame* aParent, nsIFrame* aPrevInFlow) { nsContainerFrame::Init(aContent, aParent, aPrevInFlow); const nsStyleDisplay* styleDisp = StyleContext()->StyleDisplay(); // Figure out if we should set a frame state bit to indicate that this frame // represents a legacy -webkit-{inline-}box container. // First, the trivial case: just check "display" directly. bool isLegacyBox = IsDisplayValueLegacyBox(styleDisp); // If this frame is for a scrollable element, then it will actually have // "display:block", and its *parent* will have the real flex-flavored display // value. So in that case, check the parent to find out if we're legacy. if (!isLegacyBox && styleDisp->mDisplay == mozilla::StyleDisplay::Block) { nsStyleContext* parentStyleContext = mStyleContext->GetParent(); NS_ASSERTION(parentStyleContext && (mStyleContext->GetPseudo() == nsCSSAnonBoxes::buttonContent || mStyleContext->GetPseudo() == nsCSSAnonBoxes::scrolledContent), "The only way a nsFlexContainerFrame can have 'display:block' " "should be if it's the inner part of a scrollable or button " "element"); isLegacyBox = IsDisplayValueLegacyBox(parentStyleContext->StyleDisplay()); } if (isLegacyBox) { AddStateBits(NS_STATE_FLEX_IS_LEGACY_WEBKIT_BOX); } } template<bool IsLessThanOrEqual(nsIFrame*, nsIFrame*)> /* static */ bool nsFlexContainerFrame::SortChildrenIfNeeded() { if (nsIFrame::IsFrameListSorted<IsLessThanOrEqual>(mFrames)) { return false; } nsIFrame::SortFrameList<IsLessThanOrEqual>(mFrames); return true; } /* virtual */ nsIAtom* nsFlexContainerFrame::GetType() const { return nsGkAtoms::flexContainerFrame; } #ifdef DEBUG_FRAME_DUMP nsresult nsFlexContainerFrame::GetFrameName(nsAString& aResult) const { return MakeFrameName(NS_LITERAL_STRING("FlexContainer"), aResult); } #endif nscoord nsFlexContainerFrame::GetLogicalBaseline(mozilla::WritingMode aWM) const { NS_ASSERTION(mBaselineFromLastReflow != NS_INTRINSIC_WIDTH_UNKNOWN, "baseline has not been set"); if (HasAnyStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE)) { // Return a baseline synthesized from our margin-box. return nsContainerFrame::GetLogicalBaseline(aWM); } return mBaselineFromLastReflow; } // Helper for BuildDisplayList, to implement this special-case for flex items // from the spec: // Flex items paint exactly the same as block-level elements in the // normal flow, except that 'z-index' values other than 'auto' create // a stacking context even if 'position' is 'static'. // http://www.w3.org/TR/2012/CR-css3-flexbox-20120918/#painting uint32_t GetDisplayFlagsForFlexItem(nsIFrame* aFrame) { MOZ_ASSERT(aFrame->IsFlexItem(), "Should only be called on flex items"); const nsStylePosition* pos = aFrame->StylePosition(); if (pos->mZIndex.GetUnit() == eStyleUnit_Integer) { return nsIFrame::DISPLAY_CHILD_FORCE_STACKING_CONTEXT; } return nsIFrame::DISPLAY_CHILD_FORCE_PSEUDO_STACKING_CONTEXT; } void nsFlexContainerFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder, const nsRect& aDirtyRect, const nsDisplayListSet& aLists) { // XXXdholbert hacky temporary band-aid for bug 1059138: Trivially pass this // assertion (skip it, basically) if the first child is part of a shadow DOM. // (IsOrderLEQWithDOMFallback doesn't know how to compare tree-position of a // shadow-DOM element vs. a non-shadow-DOM element.) NS_ASSERTION( (!mFrames.IsEmpty() && mFrames.FirstChild()->GetContent()->GetContainingShadow()) || nsIFrame::IsFrameListSorted<IsOrderLEQWithDOMFallback>(mFrames), "Child frames aren't sorted correctly"); DisplayBorderBackgroundOutline(aBuilder, aLists); // Our children are all block-level, so their borders/backgrounds all go on // the BlockBorderBackgrounds list. nsDisplayListSet childLists(aLists, aLists.BlockBorderBackgrounds()); for (nsIFrame* childFrame : mFrames) { BuildDisplayListForChild(aBuilder, childFrame, aDirtyRect, childLists, GetDisplayFlagsForFlexItem(childFrame)); } } void FlexLine::FreezeItemsEarly(bool aIsUsingFlexGrow) { // After we've established the type of flexing we're doing (growing vs. // shrinking), and before we try to flex any items, we freeze items that // obviously *can't* flex. // // Quoting the spec: // # Freeze, setting its target main size to its hypothetical main size... // # - any item that has a flex factor of zero // # - if using the flex grow factor: any item that has a flex base size // # greater than its hypothetical main size // # - if using the flex shrink factor: any item that has a flex base size // # smaller than its hypothetical main size // http://dev.w3.org/csswg/css-flexbox/#resolve-flexible-lengths-flex-factors // // (NOTE: At this point, item->GetMainSize() *is* the item's hypothetical // main size, since SetFlexBaseSizeAndMainSize() sets it up that way, and the // item hasn't had a chance to flex away from that yet.) // Since this loop only operates on unfrozen flex items, we can break as // soon as we have seen all of them. uint32_t numUnfrozenItemsToBeSeen = mNumItems - mNumFrozenItems; for (FlexItem* item = mItems.getFirst(); numUnfrozenItemsToBeSeen > 0; item = item->getNext()) { MOZ_ASSERT(item, "numUnfrozenItemsToBeSeen says items remain to be seen"); if (!item->IsFrozen()) { numUnfrozenItemsToBeSeen--; bool shouldFreeze = (0.0f == item->GetFlexFactor(aIsUsingFlexGrow)); if (!shouldFreeze) { if (aIsUsingFlexGrow) { if (item->GetFlexBaseSize() > item->GetMainSize()) { shouldFreeze = true; } } else { // using flex-shrink if (item->GetFlexBaseSize() < item->GetMainSize()) { shouldFreeze = true; } } } if (shouldFreeze) { // Freeze item! (at its hypothetical main size) item->Freeze(); mNumFrozenItems++; } } } } // Based on the sign of aTotalViolation, this function freezes a subset of our // flexible sizes, and restores the remaining ones to their initial pref sizes. void FlexLine::FreezeOrRestoreEachFlexibleSize(const nscoord aTotalViolation, bool aIsFinalIteration) { enum FreezeType { eFreezeEverything, eFreezeMinViolations, eFreezeMaxViolations }; FreezeType freezeType; if (aTotalViolation == 0) { freezeType = eFreezeEverything; } else if (aTotalViolation > 0) { freezeType = eFreezeMinViolations; } else { // aTotalViolation < 0 freezeType = eFreezeMaxViolations; } // Since this loop only operates on unfrozen flex items, we can break as // soon as we have seen all of them. uint32_t numUnfrozenItemsToBeSeen = mNumItems - mNumFrozenItems; for (FlexItem* item = mItems.getFirst(); numUnfrozenItemsToBeSeen > 0; item = item->getNext()) { MOZ_ASSERT(item, "numUnfrozenItemsToBeSeen says items remain to be seen"); if (!item->IsFrozen()) { numUnfrozenItemsToBeSeen--; MOZ_ASSERT(!item->HadMinViolation() || !item->HadMaxViolation(), "Can have either min or max violation, but not both"); if (eFreezeEverything == freezeType || (eFreezeMinViolations == freezeType && item->HadMinViolation()) || (eFreezeMaxViolations == freezeType && item->HadMaxViolation())) { MOZ_ASSERT(item->GetMainSize() >= item->GetMainMinSize(), "Freezing item at a size below its minimum"); MOZ_ASSERT(item->GetMainSize() <= item->GetMainMaxSize(), "Freezing item at a size above its maximum"); item->Freeze(); mNumFrozenItems++; } else if (MOZ_UNLIKELY(aIsFinalIteration)) { // XXXdholbert If & when bug 765861 is fixed, we should upgrade this // assertion to be fatal except in documents with enormous lengths. NS_ERROR("Final iteration still has unfrozen items, this shouldn't" " happen unless there was nscoord under/overflow."); item->Freeze(); mNumFrozenItems++; } // else, we'll reset this item's main size to its flex base size on the // next iteration of this algorithm. // Clear this item's violation(s), now that we've dealt with them item->ClearViolationFlags(); } } } void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize) { MOZ_LOG(gFlexContainerLog, LogLevel::Debug, ("ResolveFlexibleLengths\n")); // Determine whether we're going to be growing or shrinking items. const bool isUsingFlexGrow = (mTotalOuterHypotheticalMainSize < aFlexContainerMainSize); // Do an "early freeze" for flex items that obviously can't flex in the // direction we've chosen: FreezeItemsEarly(isUsingFlexGrow); if (mNumFrozenItems == mNumItems) { // All our items are frozen, so we have no flexible lengths to resolve. return; } MOZ_ASSERT(!IsEmpty(), "empty lines should take the early-return above"); // Subtract space occupied by our items' margins/borders/padding, so we can // just be dealing with the space available for our flex items' content // boxes. nscoord spaceReservedForMarginBorderPadding = mTotalOuterHypotheticalMainSize - mTotalInnerHypotheticalMainSize; nscoord spaceAvailableForFlexItemsContentBoxes = aFlexContainerMainSize - spaceReservedForMarginBorderPadding; nscoord origAvailableFreeSpace; bool isOrigAvailFreeSpaceInitialized = false; // NOTE: I claim that this chunk of the algorithm (the looping part) needs to // run the loop at MOST mNumItems times. This claim should hold up // because we'll freeze at least one item on each loop iteration, and once // we've run out of items to freeze, there's nothing left to do. However, // in most cases, we'll break out of this loop long before we hit that many // iterations. for (uint32_t iterationCounter = 0; iterationCounter < mNumItems; iterationCounter++) { // Set every not-yet-frozen item's used main size to its // flex base size, and subtract all the used main sizes from our // total amount of space to determine the 'available free space' // (positive or negative) to be distributed among our flexible items. nscoord availableFreeSpace = spaceAvailableForFlexItemsContentBoxes; for (FlexItem* item = mItems.getFirst(); item; item = item->getNext()) { if (!item->IsFrozen()) { item->SetMainSize(item->GetFlexBaseSize()); } availableFreeSpace -= item->GetMainSize(); } MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (" available free space = %d\n", availableFreeSpace)); // The sign of our free space should agree with the type of flexing // (grow/shrink) that we're doing (except if we've had integer overflow; // then, all bets are off). Any disagreement should've made us use the // other type of flexing, or should've been resolved in FreezeItemsEarly. // XXXdholbert If & when bug 765861 is fixed, we should upgrade this // assertion to be fatal except in documents with enormous lengths. NS_ASSERTION((isUsingFlexGrow && availableFreeSpace >= 0) || (!isUsingFlexGrow && availableFreeSpace <= 0), "availableFreeSpace's sign should match isUsingFlexGrow"); // If we have any free space available, give each flexible item a portion // of availableFreeSpace. if (availableFreeSpace != 0) { // The first time we do this, we initialize origAvailableFreeSpace. if (!isOrigAvailFreeSpaceInitialized) { origAvailableFreeSpace = availableFreeSpace; isOrigAvailFreeSpaceInitialized = true; } // STRATEGY: On each item, we compute & store its "share" of the total // weight that we've seen so far: // curWeight / weightSum // // Then, when we go to actually distribute the space (in the next loop), // we can simply walk backwards through the elements and give each item // its "share" multiplied by the remaining available space. // // SPECIAL CASE: If the sum of the weights is larger than the // maximum representable float (overflowing to infinity), then we can't // sensibly divide out proportional shares anymore. In that case, we // simply treat the flex item(s) with the largest weights as if // their weights were infinite (dwarfing all the others), and we // distribute all of the available space among them. float weightSum = 0.0f; float flexFactorSum = 0.0f; float largestWeight = 0.0f; uint32_t numItemsWithLargestWeight = 0; // Since this loop only operates on unfrozen flex items, we can break as // soon as we have seen all of them. uint32_t numUnfrozenItemsToBeSeen = mNumItems - mNumFrozenItems; for (FlexItem* item = mItems.getFirst(); numUnfrozenItemsToBeSeen > 0; item = item->getNext()) { MOZ_ASSERT(item, "numUnfrozenItemsToBeSeen says items remain to be seen"); if (!item->IsFrozen()) { numUnfrozenItemsToBeSeen--; float curWeight = item->GetWeight(isUsingFlexGrow); float curFlexFactor = item->GetFlexFactor(isUsingFlexGrow); MOZ_ASSERT(curWeight >= 0.0f, "weights are non-negative"); MOZ_ASSERT(curFlexFactor >= 0.0f, "flex factors are non-negative"); weightSum += curWeight; flexFactorSum += curFlexFactor; if (IsFinite(weightSum)) { if (curWeight == 0.0f) { item->SetShareOfWeightSoFar(0.0f); } else { item->SetShareOfWeightSoFar(curWeight / weightSum); } } // else, the sum of weights overflows to infinity, in which // case we don't bother with "SetShareOfWeightSoFar" since // we know we won't use it. (instead, we'll just give every // item with the largest weight an equal share of space.) // Update our largest-weight tracking vars if (curWeight > largestWeight) { largestWeight = curWeight; numItemsWithLargestWeight = 1; } else if (curWeight == largestWeight) { numItemsWithLargestWeight++; } } } if (weightSum != 0.0f) { MOZ_ASSERT(flexFactorSum != 0.0f, "flex factor sum can't be 0, if a weighted sum " "of its components (weightSum) is nonzero"); if (flexFactorSum < 1.0f) { // Our unfrozen flex items don't want all of the original free space! // (Their flex factors add up to something less than 1.) // Hence, make sure we don't distribute any more than the portion of // our original free space that these items actually want. nscoord totalDesiredPortionOfOrigFreeSpace = NSToCoordRound(origAvailableFreeSpace * flexFactorSum); // Clamp availableFreeSpace to be no larger than that ^^. // (using min or max, depending on sign). // This should not change the sign of availableFreeSpace (except // possibly by setting it to 0), as enforced by this assertion: MOZ_ASSERT(totalDesiredPortionOfOrigFreeSpace == 0 || ((totalDesiredPortionOfOrigFreeSpace > 0) == (availableFreeSpace > 0)), "When we reduce available free space for flex factors < 1," "we shouldn't change the sign of the free space..."); if (availableFreeSpace > 0) { availableFreeSpace = std::min(availableFreeSpace, totalDesiredPortionOfOrigFreeSpace); } else { availableFreeSpace = std::max(availableFreeSpace, totalDesiredPortionOfOrigFreeSpace); } } MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (" Distributing available space:")); // Since this loop only operates on unfrozen flex items, we can break as // soon as we have seen all of them. numUnfrozenItemsToBeSeen = mNumItems - mNumFrozenItems; // NOTE: It's important that we traverse our items in *reverse* order // here, for correct width distribution according to the items' // "ShareOfWeightSoFar" progressively-calculated values. for (FlexItem* item = mItems.getLast(); numUnfrozenItemsToBeSeen > 0; item = item->getPrevious()) { MOZ_ASSERT(item, "numUnfrozenItemsToBeSeen says items remain to be seen"); if (!item->IsFrozen()) { numUnfrozenItemsToBeSeen--; // To avoid rounding issues, we compute the change in size for this // item, and then subtract it from the remaining available space. nscoord sizeDelta = 0; if (IsFinite(weightSum)) { float myShareOfRemainingSpace = item->GetShareOfWeightSoFar(); MOZ_ASSERT(myShareOfRemainingSpace >= 0.0f && myShareOfRemainingSpace <= 1.0f, "my share should be nonnegative fractional amount"); if (myShareOfRemainingSpace == 1.0f) { // (We special-case 1.0f to avoid float error from converting // availableFreeSpace from integer*1.0f --> float --> integer) sizeDelta = availableFreeSpace; } else if (myShareOfRemainingSpace > 0.0f) { sizeDelta = NSToCoordRound(availableFreeSpace * myShareOfRemainingSpace); } } else if (item->GetWeight(isUsingFlexGrow) == largestWeight) { // Total flexibility is infinite, so we're just distributing // the available space equally among the items that are tied for // having the largest weight (and this is one of those items). sizeDelta = NSToCoordRound(availableFreeSpace / float(numItemsWithLargestWeight)); numItemsWithLargestWeight--; } availableFreeSpace -= sizeDelta; item->SetMainSize(item->GetMainSize() + sizeDelta); MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (" child %p receives %d, for a total of %d\n", item, sizeDelta, item->GetMainSize())); } } } } // Fix min/max violations: nscoord totalViolation = 0; // keeps track of adjustments for min/max MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (" Checking for violations:")); // Since this loop only operates on unfrozen flex items, we can break as // soon as we have seen all of them. uint32_t numUnfrozenItemsToBeSeen = mNumItems - mNumFrozenItems; for (FlexItem* item = mItems.getFirst(); numUnfrozenItemsToBeSeen > 0; item = item->getNext()) { MOZ_ASSERT(item, "numUnfrozenItemsToBeSeen says items remain to be seen"); if (!item->IsFrozen()) { numUnfrozenItemsToBeSeen--; if (item->GetMainSize() < item->GetMainMinSize()) { // min violation totalViolation += item->GetMainMinSize() - item->GetMainSize(); item->SetMainSize(item->GetMainMinSize()); item->SetHadMinViolation(); } else if (item->GetMainSize() > item->GetMainMaxSize()) { // max violation totalViolation += item->GetMainMaxSize() - item->GetMainSize(); item->SetMainSize(item->GetMainMaxSize()); item->SetHadMaxViolation(); } } } FreezeOrRestoreEachFlexibleSize(totalViolation, iterationCounter + 1 == mNumItems); MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (" Total violation: %d\n", totalViolation)); if (mNumFrozenItems == mNumItems) { break; } MOZ_ASSERT(totalViolation != 0, "Zero violation should've made us freeze all items & break"); } #ifdef DEBUG // Post-condition: all items should've been frozen. // Make sure the counts match: MOZ_ASSERT(mNumFrozenItems == mNumItems, "All items should be frozen"); // For good measure, check each item directly, in case our counts are busted: for (const FlexItem* item = mItems.getFirst(); item; item = item->getNext()) { MOZ_ASSERT(item->IsFrozen(), "All items should be frozen"); } #endif // DEBUG } MainAxisPositionTracker:: MainAxisPositionTracker(const FlexboxAxisTracker& aAxisTracker, const FlexLine* aLine, uint8_t aJustifyContent, nscoord aContentBoxMainSize) : PositionTracker(aAxisTracker.GetMainAxis(), aAxisTracker.IsMainAxisReversed()), mPackingSpaceRemaining(aContentBoxMainSize), // we chip away at this below mNumAutoMarginsInMainAxis(0), mNumPackingSpacesRemaining(0), mJustifyContent(aJustifyContent) { // 'normal' behaves as 'stretch', and 'stretch' behaves as 'flex-start', // in the main axis // https://drafts.csswg.org/css-align-3/#propdef-justify-content if (mJustifyContent == NS_STYLE_JUSTIFY_NORMAL || mJustifyContent == NS_STYLE_JUSTIFY_STRETCH) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_START; } // XXX strip off the <overflow-position> bit until we implement that mJustifyContent &= ~NS_STYLE_JUSTIFY_FLAG_BITS; // mPackingSpaceRemaining is initialized to the container's main size. Now // we'll subtract out the main sizes of our flex items, so that it ends up // with the *actual* amount of packing space. for (const FlexItem* item = aLine->GetFirstItem(); item; item = item->getNext()) { mPackingSpaceRemaining -= item->GetOuterMainSize(mAxis); mNumAutoMarginsInMainAxis += item->GetNumAutoMarginsInAxis(mAxis); } if (mPackingSpaceRemaining <= 0) { // No available packing space to use for resolving auto margins. mNumAutoMarginsInMainAxis = 0; } // If packing space is negative, 'space-between' falls back to 'flex-start', // and 'space-around' & 'space-evenly' fall back to 'center'. In those cases, // it's simplest to just pretend we have a different 'justify-content' value // and share code. if (mPackingSpaceRemaining < 0) { if (mJustifyContent == NS_STYLE_JUSTIFY_SPACE_BETWEEN) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_START; } else if (mJustifyContent == NS_STYLE_JUSTIFY_SPACE_AROUND || mJustifyContent == NS_STYLE_JUSTIFY_SPACE_EVENLY) { mJustifyContent = NS_STYLE_JUSTIFY_CENTER; } } // Map 'left'/'right' to 'start'/'end' if (mJustifyContent == NS_STYLE_JUSTIFY_LEFT || mJustifyContent == NS_STYLE_JUSTIFY_RIGHT) { if (aAxisTracker.IsColumnOriented()) { // Container's alignment axis is not parallel to the inline axis, // so we map both 'left' and 'right' to 'start'. mJustifyContent = NS_STYLE_JUSTIFY_START; } else { // Row-oriented, so we map 'left' and 'right' to 'start' or 'end', // depending on left-to-right writing mode. const bool isLTR = aAxisTracker.GetWritingMode().IsBidiLTR(); const bool isJustifyLeft = (mJustifyContent == NS_STYLE_JUSTIFY_LEFT); mJustifyContent = (isJustifyLeft == isLTR) ? NS_STYLE_JUSTIFY_START : NS_STYLE_JUSTIFY_END; } } // Map 'start'/'end' to 'flex-start'/'flex-end'. if (mJustifyContent == NS_STYLE_JUSTIFY_START) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_START; } else if (mJustifyContent == NS_STYLE_JUSTIFY_END) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_END; } // If our main axis is (internally) reversed, swap the justify-content // "flex-start" and "flex-end" behaviors: if (aAxisTracker.AreAxesInternallyReversed()) { if (mJustifyContent == NS_STYLE_JUSTIFY_FLEX_START) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_END; } else if (mJustifyContent == NS_STYLE_JUSTIFY_FLEX_END) { mJustifyContent = NS_STYLE_JUSTIFY_FLEX_START; } } // Figure out how much space we'll set aside for auto margins or // packing spaces, and advance past any leading packing-space. if (mNumAutoMarginsInMainAxis == 0 && mPackingSpaceRemaining != 0 && !aLine->IsEmpty()) { switch (mJustifyContent) { case NS_STYLE_JUSTIFY_BASELINE: case NS_STYLE_JUSTIFY_LAST_BASELINE: NS_WARNING("NYI: justify-content:left/right/baseline/last baseline"); MOZ_FALLTHROUGH; case NS_STYLE_JUSTIFY_FLEX_START: // All packing space should go at the end --> nothing to do here. break; case NS_STYLE_JUSTIFY_FLEX_END: // All packing space goes at the beginning mPosition += mPackingSpaceRemaining; break; case NS_STYLE_JUSTIFY_CENTER: // Half the packing space goes at the beginning mPosition += mPackingSpaceRemaining / 2; break; case NS_STYLE_JUSTIFY_SPACE_BETWEEN: case NS_STYLE_JUSTIFY_SPACE_AROUND: case NS_STYLE_JUSTIFY_SPACE_EVENLY: nsFlexContainerFrame::CalculatePackingSpace(aLine->NumItems(), mJustifyContent, &mPosition, &mNumPackingSpacesRemaining, &mPackingSpaceRemaining); break; default: MOZ_ASSERT_UNREACHABLE("Unexpected justify-content value"); } } MOZ_ASSERT(mNumPackingSpacesRemaining == 0 || mNumAutoMarginsInMainAxis == 0, "extra space should either go to packing space or to " "auto margins, but not to both"); } void MainAxisPositionTracker::ResolveAutoMarginsInMainAxis(FlexItem& aItem) { if (mNumAutoMarginsInMainAxis) { const nsStyleSides& styleMargin = aItem.Frame()->StyleMargin()->mMargin; for (uint32_t i = 0; i < eNumAxisEdges; i++) { mozilla::Side side = kAxisOrientationToSidesMap[mAxis][i]; if (styleMargin.GetUnit(side) == eStyleUnit_Auto) { // NOTE: This integer math will skew the distribution of remainder // app-units towards the end, which is fine. nscoord curAutoMarginSize = mPackingSpaceRemaining / mNumAutoMarginsInMainAxis; MOZ_ASSERT(aItem.GetMarginComponentForSide(side) == 0, "Expecting auto margins to have value '0' before we " "resolve them"); aItem.SetMarginComponentForSide(side, curAutoMarginSize); mNumAutoMarginsInMainAxis--; mPackingSpaceRemaining -= curAutoMarginSize; } } } } void MainAxisPositionTracker::TraversePackingSpace() { if (mNumPackingSpacesRemaining) { MOZ_ASSERT(mJustifyContent == NS_STYLE_JUSTIFY_SPACE_BETWEEN || mJustifyContent == NS_STYLE_JUSTIFY_SPACE_AROUND || mJustifyContent == NS_STYLE_JUSTIFY_SPACE_EVENLY, "mNumPackingSpacesRemaining only applies for " "space-between/space-around/space-evenly"); MOZ_ASSERT(mPackingSpaceRemaining >= 0, "ran out of packing space earlier than we expected"); // NOTE: This integer math will skew the distribution of remainder // app-units towards the end, which is fine. nscoord curPackingSpace = mPackingSpaceRemaining / mNumPackingSpacesRemaining; mPosition += curPackingSpace; mNumPackingSpacesRemaining--; mPackingSpaceRemaining -= curPackingSpace; } } CrossAxisPositionTracker:: CrossAxisPositionTracker(FlexLine* aFirstLine, const ReflowInput& aReflowInput, nscoord aContentBoxCrossSize, bool aIsCrossSizeDefinite, const FlexboxAxisTracker& aAxisTracker) : PositionTracker(aAxisTracker.GetCrossAxis(), aAxisTracker.IsCrossAxisReversed()), mPackingSpaceRemaining(0), mNumPackingSpacesRemaining(0), mAlignContent(aReflowInput.mStylePosition->mAlignContent) { MOZ_ASSERT(aFirstLine, "null first line pointer"); // 'normal' behaves as 'stretch' if (mAlignContent == NS_STYLE_ALIGN_NORMAL) { mAlignContent = NS_STYLE_ALIGN_STRETCH; } // XXX strip of the <overflow-position> bit until we implement that mAlignContent &= ~NS_STYLE_ALIGN_FLAG_BITS; const bool isSingleLine = NS_STYLE_FLEX_WRAP_NOWRAP == aReflowInput.mStylePosition->mFlexWrap; if (isSingleLine) { MOZ_ASSERT(!aFirstLine->getNext(), "If we're styled as single-line, we should only have 1 line"); // "If the flex container is single-line and has a definite cross size, the // cross size of the flex line is the flex container's inner cross size." // // SOURCE: https://drafts.csswg.org/css-flexbox/#algo-cross-line // NOTE: This means (by definition) that there's no packing space, which // means we don't need to be concerned with "align-conent" at all and we // can return early. This is handy, because this is the usual case (for // single-line flexbox). if (aIsCrossSizeDefinite) { aFirstLine->SetLineCrossSize(aContentBoxCrossSize); return; } // "If the flex container is single-line, then clamp the line's // cross-size to be within the container's computed min and max cross-size // properties." aFirstLine->SetLineCrossSize(NS_CSS_MINMAX(aFirstLine->GetLineCrossSize(), aReflowInput.ComputedMinBSize(), aReflowInput.ComputedMaxBSize())); } // NOTE: The rest of this function should essentially match // MainAxisPositionTracker's constructor, though with FlexLines instead of // FlexItems, and with the additional value "stretch" (and of course with // cross sizes instead of main sizes.) // Figure out how much packing space we have (container's cross size minus // all the lines' cross sizes). Also, share this loop to count how many // lines we have. (We need that count in some cases below.) mPackingSpaceRemaining = aContentBoxCrossSize; uint32_t numLines = 0; for (FlexLine* line = aFirstLine; line; line = line->getNext()) { mPackingSpaceRemaining -= line->GetLineCrossSize(); numLines++; } // If packing space is negative, 'space-between' and 'stretch' behave like // 'flex-start', and 'space-around' and 'space-evenly' behave like 'center'. // In those cases, it's simplest to just pretend we have a different // 'align-content' value and share code. if (mPackingSpaceRemaining < 0) { if (mAlignContent == NS_STYLE_ALIGN_SPACE_BETWEEN || mAlignContent == NS_STYLE_ALIGN_STRETCH) { mAlignContent = NS_STYLE_ALIGN_FLEX_START; } else if (mAlignContent == NS_STYLE_ALIGN_SPACE_AROUND || mAlignContent == NS_STYLE_ALIGN_SPACE_EVENLY) { mAlignContent = NS_STYLE_ALIGN_CENTER; } } // Map 'left'/'right' to 'start'/'end' if (mAlignContent == NS_STYLE_ALIGN_LEFT || mAlignContent == NS_STYLE_ALIGN_RIGHT) { if (aAxisTracker.IsRowOriented()) { // Container's alignment axis is not parallel to the inline axis, // so we map both 'left' and 'right' to 'start'. mAlignContent = NS_STYLE_ALIGN_START; } else { // Column-oriented, so we map 'left' and 'right' to 'start' or 'end', // depending on left-to-right writing mode. const bool isLTR = aAxisTracker.GetWritingMode().IsBidiLTR(); const bool isAlignLeft = (mAlignContent == NS_STYLE_ALIGN_LEFT); mAlignContent = (isAlignLeft == isLTR) ? NS_STYLE_ALIGN_START : NS_STYLE_ALIGN_END; } } // Map 'start'/'end' to 'flex-start'/'flex-end'. if (mAlignContent == NS_STYLE_ALIGN_START) { mAlignContent = NS_STYLE_ALIGN_FLEX_START; } else if (mAlignContent == NS_STYLE_ALIGN_END) { mAlignContent = NS_STYLE_ALIGN_FLEX_END; } // If our cross axis is (internally) reversed, swap the align-content // "flex-start" and "flex-end" behaviors: if (aAxisTracker.AreAxesInternallyReversed()) { if (mAlignContent == NS_STYLE_ALIGN_FLEX_START) { mAlignContent = NS_STYLE_ALIGN_FLEX_END; } else if (mAlignContent == NS_STYLE_ALIGN_FLEX_END) { mAlignContent = NS_STYLE_ALIGN_FLEX_START; } } // Figure out how much space we'll set aside for packing spaces, and advance // past any leading packing-space. if (mPackingSpaceRemaining != 0) { switch (mAlignContent) { case NS_STYLE_ALIGN_SELF_START: case NS_STYLE_ALIGN_SELF_END: case NS_STYLE_ALIGN_BASELINE: case NS_STYLE_ALIGN_LAST_BASELINE: NS_WARNING("NYI: align-items/align-self:left/right/self-start/self-end/baseline/last baseline"); MOZ_FALLTHROUGH; case NS_STYLE_ALIGN_FLEX_START: // All packing space should go at the end --> nothing to do here. break; case NS_STYLE_ALIGN_FLEX_END: // All packing space goes at the beginning mPosition += mPackingSpaceRemaining; break; case NS_STYLE_ALIGN_CENTER: // Half the packing space goes at the beginning mPosition += mPackingSpaceRemaining / 2; break; case NS_STYLE_ALIGN_SPACE_BETWEEN: case NS_STYLE_ALIGN_SPACE_AROUND: case NS_STYLE_ALIGN_SPACE_EVENLY: nsFlexContainerFrame::CalculatePackingSpace(numLines, mAlignContent, &mPosition, &mNumPackingSpacesRemaining, &mPackingSpaceRemaining); break; case NS_STYLE_ALIGN_STRETCH: { // Split space equally between the lines: MOZ_ASSERT(mPackingSpaceRemaining > 0, "negative packing space should make us use 'flex-start' " "instead of 'stretch' (and we shouldn't bother with this " "code if we have 0 packing space)"); uint32_t numLinesLeft = numLines; for (FlexLine* line = aFirstLine; line; line = line->getNext()) { // Our share is the amount of space remaining, divided by the number // of lines remainig. MOZ_ASSERT(numLinesLeft > 0, "miscalculated num lines"); nscoord shareOfExtraSpace = mPackingSpaceRemaining / numLinesLeft; nscoord newSize = line->GetLineCrossSize() + shareOfExtraSpace; line->SetLineCrossSize(newSize); mPackingSpaceRemaining -= shareOfExtraSpace; numLinesLeft--; } MOZ_ASSERT(numLinesLeft == 0, "miscalculated num lines"); break; } default: MOZ_ASSERT_UNREACHABLE("Unexpected align-content value"); } } } void CrossAxisPositionTracker::TraversePackingSpace() { if (mNumPackingSpacesRemaining) { MOZ_ASSERT(mAlignContent == NS_STYLE_ALIGN_SPACE_BETWEEN || mAlignContent == NS_STYLE_ALIGN_SPACE_AROUND || mAlignContent == NS_STYLE_ALIGN_SPACE_EVENLY, "mNumPackingSpacesRemaining only applies for " "space-between/space-around/space-evenly"); MOZ_ASSERT(mPackingSpaceRemaining >= 0, "ran out of packing space earlier than we expected"); // NOTE: This integer math will skew the distribution of remainder // app-units towards the end, which is fine. nscoord curPackingSpace = mPackingSpaceRemaining / mNumPackingSpacesRemaining; mPosition += curPackingSpace; mNumPackingSpacesRemaining--; mPackingSpaceRemaining -= curPackingSpace; } } SingleLineCrossAxisPositionTracker:: SingleLineCrossAxisPositionTracker(const FlexboxAxisTracker& aAxisTracker) : PositionTracker(aAxisTracker.GetCrossAxis(), aAxisTracker.IsCrossAxisReversed()) { } void FlexLine::ComputeCrossSizeAndBaseline(const FlexboxAxisTracker& aAxisTracker) { nscoord crossStartToFurthestFirstBaseline = nscoord_MIN; nscoord crossEndToFurthestFirstBaseline = nscoord_MIN; nscoord crossStartToFurthestLastBaseline = nscoord_MIN; nscoord crossEndToFurthestLastBaseline = nscoord_MIN; nscoord largestOuterCrossSize = 0; for (const FlexItem* item = mItems.getFirst(); item; item = item->getNext()) { nscoord curOuterCrossSize = item->GetOuterCrossSize(aAxisTracker.GetCrossAxis()); if ((item->GetAlignSelf() == NS_STYLE_ALIGN_BASELINE || item->GetAlignSelf() == NS_STYLE_ALIGN_LAST_BASELINE) && item->GetNumAutoMarginsInAxis(aAxisTracker.GetCrossAxis()) == 0) { const bool useFirst = (item->GetAlignSelf() == NS_STYLE_ALIGN_BASELINE); // FIXME: Once we support "writing-mode", we'll have to do baseline // alignment in vertical flex containers here (w/ horizontal cross-axes). // Find distance from our item's cross-start and cross-end margin-box // edges to its baseline. // // Here's a diagram of a flex-item that we might be doing this on. // "mmm" is the margin-box, "bbb" is the border-box. The bottom of // the text "BASE" is the baseline. // // ---(cross-start)--- // ___ ___ ___ // mmmmmmmmmmmm | |margin-start | // m m | _|_ ___ | // m bbbbbbbb m |curOuterCrossSize | |crossStartToBaseline // m b b m | |ascent | // m b BASE b m | _|_ _|_ // m b b m | | // m bbbbbbbb m | |crossEndToBaseline // m m | | // mmmmmmmmmmmm _|_ _|_ // // ---(cross-end)--- // // We already have the curOuterCrossSize, margin-start, and the ascent. // * We can get crossStartToBaseline by adding margin-start + ascent. // * If we subtract that from the curOuterCrossSize, we get // crossEndToBaseline. nscoord crossStartToBaseline = item->GetBaselineOffsetFromOuterCrossEdge(eAxisEdge_Start, aAxisTracker, useFirst); nscoord crossEndToBaseline = curOuterCrossSize - crossStartToBaseline; // Now, update our "largest" values for these (across all the flex items // in this flex line), so we can use them in computing the line's cross // size below: if (useFirst) { crossStartToFurthestFirstBaseline = std::max(crossStartToFurthestFirstBaseline, crossStartToBaseline); crossEndToFurthestFirstBaseline = std::max(crossEndToFurthestFirstBaseline, crossEndToBaseline); } else { crossStartToFurthestLastBaseline = std::max(crossStartToFurthestLastBaseline, crossStartToBaseline); crossEndToFurthestLastBaseline = std::max(crossEndToFurthestLastBaseline, crossEndToBaseline); } } else { largestOuterCrossSize = std::max(largestOuterCrossSize, curOuterCrossSize); } } // The line's baseline offset is the distance from the line's edge (start or // end, depending on whether we've flipped the axes) to the furthest // item-baseline. The item(s) with that baseline will be exactly aligned with // the line's edge. mFirstBaselineOffset = aAxisTracker.AreAxesInternallyReversed() ? crossEndToFurthestFirstBaseline : crossStartToFurthestFirstBaseline; mLastBaselineOffset = aAxisTracker.AreAxesInternallyReversed() ? crossStartToFurthestLastBaseline : crossEndToFurthestLastBaseline; // The line's cross-size is the larger of: // (a) [largest cross-start-to-baseline + largest baseline-to-cross-end] of // all baseline-aligned items with no cross-axis auto margins... // and // (b) [largest cross-start-to-baseline + largest baseline-to-cross-end] of // all last baseline-aligned items with no cross-axis auto margins... // and // (c) largest cross-size of all other children. mLineCrossSize = std::max( std::max(crossStartToFurthestFirstBaseline + crossEndToFurthestFirstBaseline, crossStartToFurthestLastBaseline + crossEndToFurthestLastBaseline), largestOuterCrossSize); } void FlexItem::ResolveStretchedCrossSize(nscoord aLineCrossSize, const FlexboxAxisTracker& aAxisTracker) { AxisOrientationType crossAxis = aAxisTracker.GetCrossAxis(); // We stretch IFF we are align-self:stretch, have no auto margins in // cross axis, and have cross-axis size property == "auto". If any of those // conditions don't hold up, we won't stretch. if (mAlignSelf != NS_STYLE_ALIGN_STRETCH || GetNumAutoMarginsInAxis(crossAxis) != 0 || eStyleUnit_Auto != aAxisTracker.ComputedCrossSize(mFrame).GetUnit()) { return; } // If we've already been stretched, we can bail out early, too. // No need to redo the calculation. if (mIsStretched) { return; } // Reserve space for margins & border & padding, and then use whatever // remains as our item's cross-size (clamped to its min/max range). nscoord stretchedSize = aLineCrossSize - GetMarginBorderPaddingSizeInAxis(crossAxis); stretchedSize = NS_CSS_MINMAX(stretchedSize, mCrossMinSize, mCrossMaxSize); // Update the cross-size & make a note that it's stretched, so we know to // override the reflow state's computed cross-size in our final reflow. SetCrossSize(stretchedSize); mIsStretched = true; } void SingleLineCrossAxisPositionTracker:: ResolveAutoMarginsInCrossAxis(const FlexLine& aLine, FlexItem& aItem) { // Subtract the space that our item is already occupying, to see how much // space (if any) is available for its auto margins. nscoord spaceForAutoMargins = aLine.GetLineCrossSize() - aItem.GetOuterCrossSize(mAxis); if (spaceForAutoMargins <= 0) { return; // No available space --> nothing to do } uint32_t numAutoMargins = aItem.GetNumAutoMarginsInAxis(mAxis); if (numAutoMargins == 0) { return; // No auto margins --> nothing to do. } // OK, we have at least one auto margin and we have some available space. // Give each auto margin a share of the space. const nsStyleSides& styleMargin = aItem.Frame()->StyleMargin()->mMargin; for (uint32_t i = 0; i < eNumAxisEdges; i++) { mozilla::Side side = kAxisOrientationToSidesMap[mAxis][i]; if (styleMargin.GetUnit(side) == eStyleUnit_Auto) { MOZ_ASSERT(aItem.GetMarginComponentForSide(side) == 0, "Expecting auto margins to have value '0' before we " "update them"); // NOTE: integer divison is fine here; numAutoMargins is either 1 or 2. // If it's 2 & spaceForAutoMargins is odd, 1st margin gets smaller half. nscoord curAutoMarginSize = spaceForAutoMargins / numAutoMargins; aItem.SetMarginComponentForSide(side, curAutoMarginSize); numAutoMargins--; spaceForAutoMargins -= curAutoMarginSize; } } } void SingleLineCrossAxisPositionTracker:: EnterAlignPackingSpace(const FlexLine& aLine, const FlexItem& aItem, const FlexboxAxisTracker& aAxisTracker) { // We don't do align-self alignment on items that have auto margins // in the cross axis. if (aItem.GetNumAutoMarginsInAxis(mAxis)) { return; } uint8_t alignSelf = aItem.GetAlignSelf(); // NOTE: 'stretch' behaves like 'flex-start' once we've stretched any // auto-sized items (which we've already done). if (alignSelf == NS_STYLE_ALIGN_STRETCH) { alignSelf = NS_STYLE_ALIGN_FLEX_START; } // Map 'left'/'right' to 'start'/'end' if (alignSelf == NS_STYLE_ALIGN_LEFT || alignSelf == NS_STYLE_ALIGN_RIGHT) { if (aAxisTracker.IsRowOriented()) { // Container's alignment axis is not parallel to the inline axis, // so we map both 'left' and 'right' to 'start'. alignSelf = NS_STYLE_ALIGN_START; } else { // Column-oriented, so we map 'left' and 'right' to 'start' or 'end', // depending on left-to-right writing mode. const bool isLTR = aAxisTracker.GetWritingMode().IsBidiLTR(); const bool isAlignLeft = (alignSelf == NS_STYLE_ALIGN_LEFT); alignSelf = (isAlignLeft == isLTR) ? NS_STYLE_ALIGN_START : NS_STYLE_ALIGN_END; } } // Map 'start'/'end' to 'flex-start'/'flex-end'. if (alignSelf == NS_STYLE_ALIGN_START) { alignSelf = NS_STYLE_ALIGN_FLEX_START; } else if (alignSelf == NS_STYLE_ALIGN_END) { alignSelf = NS_STYLE_ALIGN_FLEX_END; } // If our cross axis is (internally) reversed, swap the align-self // "flex-start" and "flex-end" behaviors: if (aAxisTracker.AreAxesInternallyReversed()) { if (alignSelf == NS_STYLE_ALIGN_FLEX_START) { alignSelf = NS_STYLE_ALIGN_FLEX_END; } else if (alignSelf == NS_STYLE_ALIGN_FLEX_END) { alignSelf = NS_STYLE_ALIGN_FLEX_START; } } switch (alignSelf) { case NS_STYLE_ALIGN_SELF_START: case NS_STYLE_ALIGN_SELF_END: NS_WARNING("NYI: align-items/align-self:left/right/self-start/self-end"); MOZ_FALLTHROUGH; case NS_STYLE_ALIGN_FLEX_START: // No space to skip over -- we're done. break; case NS_STYLE_ALIGN_FLEX_END: mPosition += aLine.GetLineCrossSize() - aItem.GetOuterCrossSize(mAxis); break; case NS_STYLE_ALIGN_CENTER: // Note: If cross-size is odd, the "after" space will get the extra unit. mPosition += (aLine.GetLineCrossSize() - aItem.GetOuterCrossSize(mAxis)) / 2; break; case NS_STYLE_ALIGN_BASELINE: case NS_STYLE_ALIGN_LAST_BASELINE: { const bool useFirst = (alignSelf == NS_STYLE_ALIGN_BASELINE); // Normally, baseline-aligned items are collectively aligned with the // line's cross-start edge; however, if our cross axis is (internally) // reversed, we instead align them with the cross-end edge. // A similar logic holds for last baseline-aligned items, but in reverse. AxisEdgeType baselineAlignEdge = aAxisTracker.AreAxesInternallyReversed() == useFirst ? eAxisEdge_End : eAxisEdge_Start; nscoord itemBaselineOffset = aItem.GetBaselineOffsetFromOuterCrossEdge(baselineAlignEdge, aAxisTracker, useFirst); nscoord lineBaselineOffset = useFirst ? aLine.GetFirstBaselineOffset() : aLine.GetLastBaselineOffset(); NS_ASSERTION(lineBaselineOffset >= itemBaselineOffset, "failed at finding largest baseline offset"); // How much do we need to adjust our position (from the line edge), // to get the item's baseline to hit the line's baseline offset: nscoord baselineDiff = lineBaselineOffset - itemBaselineOffset; if (aAxisTracker.AreAxesInternallyReversed() == useFirst) { // Advance to align item w/ line's flex-end edge (as in FLEX_END case): mPosition += aLine.GetLineCrossSize() - aItem.GetOuterCrossSize(mAxis); // ...and step *back* by the baseline adjustment: mPosition -= baselineDiff; } else { // mPosition is already at line's flex-start edge. // From there, we step *forward* by the baseline adjustment: mPosition += baselineDiff; } break; } default: MOZ_ASSERT_UNREACHABLE("Unexpected align-self value"); break; } } // Utility function to convert an InlineDir to an AxisOrientationType static inline AxisOrientationType InlineDirToAxisOrientation(WritingMode::InlineDir aInlineDir) { switch (aInlineDir) { case WritingMode::eInlineLTR: return eAxis_LR; case WritingMode::eInlineRTL: return eAxis_RL; case WritingMode::eInlineTTB: return eAxis_TB; case WritingMode::eInlineBTT: return eAxis_BT; } MOZ_ASSERT_UNREACHABLE("Unhandled InlineDir"); return eAxis_LR; // in case of unforseen error, assume English LTR text flow. } // Utility function to convert a BlockDir to an AxisOrientationType static inline AxisOrientationType BlockDirToAxisOrientation(WritingMode::BlockDir aBlockDir) { switch (aBlockDir) { case WritingMode::eBlockLR: return eAxis_LR; case WritingMode::eBlockRL: return eAxis_RL; case WritingMode::eBlockTB: return eAxis_TB; // NOTE: WritingMode::eBlockBT (bottom-to-top) does not exist. } MOZ_ASSERT_UNREACHABLE("Unhandled BlockDir"); return eAxis_TB; // in case of unforseen error, assume English TTB block-flow } FlexboxAxisTracker::FlexboxAxisTracker( const nsFlexContainerFrame* aFlexContainer, const WritingMode& aWM, AxisTrackerFlags aFlags) : mWM(aWM), mAreAxesInternallyReversed(false) { if (IsLegacyBox(aFlexContainer)) { InitAxesFromLegacyProps(aFlexContainer); } else { InitAxesFromModernProps(aFlexContainer); } // Master switch to enable/disable bug 983427's code for reversing our axes // and reversing some logic, to avoid reflowing children in bottom-to-top // order. (This switch can be removed eventually, but for now, it allows // this special-case code path to be compared against the normal code path.) static bool sPreventBottomToTopChildOrdering = true; // Note: if the eAllowBottomToTopChildOrdering flag is set, that overrides // the static boolean and makes us skip this special case. if (!(aFlags & AxisTrackerFlags::eAllowBottomToTopChildOrdering) && sPreventBottomToTopChildOrdering) { // If either axis is bottom-to-top, we flip both axes (and set a flag // so that we can flip some logic to make the reversal transparent). if (eAxis_BT == mMainAxis || eAxis_BT == mCrossAxis) { mMainAxis = GetReverseAxis(mMainAxis); mCrossAxis = GetReverseAxis(mCrossAxis); mAreAxesInternallyReversed = true; mIsMainAxisReversed = !mIsMainAxisReversed; mIsCrossAxisReversed = !mIsCrossAxisReversed; } } } void FlexboxAxisTracker::InitAxesFromLegacyProps( const nsFlexContainerFrame* aFlexContainer) { const nsStyleXUL* styleXUL = aFlexContainer->StyleXUL(); const bool boxOrientIsVertical = (styleXUL->mBoxOrient == StyleBoxOrient::Vertical); const bool wmIsVertical = mWM.IsVertical(); // If box-orient agrees with our writing-mode, then we're "row-oriented" // (i.e. the flexbox main axis is the same as our writing mode's inline // direction). Otherwise, we're column-oriented (i.e. the flexbox's main // axis is perpendicular to the writing-mode's inline direction). mIsRowOriented = (boxOrientIsVertical == wmIsVertical); // XXXdholbert BEGIN CODE TO SET DEPRECATED MEMBER-VARS if (boxOrientIsVertical) { mMainAxis = eAxis_TB; mCrossAxis = eAxis_LR; } else { mMainAxis = eAxis_LR; mCrossAxis = eAxis_TB; } // "direction: rtl" reverses the writing-mode's inline axis. // So, we need to reverse the corresponding flex axis to match. // (Note this we don't toggle "mIsMainAxisReversed" for this condition, // because the main axis will still match mWM's inline direction.) if (!mWM.IsBidiLTR()) { AxisOrientationType& axisToFlip = mIsRowOriented ? mMainAxis : mCrossAxis; axisToFlip = GetReverseAxis(axisToFlip); } // XXXdholbert END CODE TO SET DEPRECATED MEMBER-VARS // Legacy flexbox can use "-webkit-box-direction: reverse" to reverse the // main axis (so it runs in the reverse direction of the inline axis): if (styleXUL->mBoxDirection == StyleBoxDirection::Reverse) { mMainAxis = GetReverseAxis(mMainAxis); mIsMainAxisReversed = true; } else { mIsMainAxisReversed = false; } // Legacy flexbox does not support reversing the cross axis -- it has no // equivalent of modern flexbox's "flex-wrap: wrap-reverse". mIsCrossAxisReversed = false; } void FlexboxAxisTracker::InitAxesFromModernProps( const nsFlexContainerFrame* aFlexContainer) { const nsStylePosition* stylePos = aFlexContainer->StylePosition(); uint32_t flexDirection = stylePos->mFlexDirection; // Inline dimension ("start-to-end"): // (NOTE: I'm intentionally not calling these "inlineAxis"/"blockAxis", since // those terms have explicit definition in the writing-modes spec, which are // the opposite of how I'd be using them here.) AxisOrientationType inlineDimension = InlineDirToAxisOrientation(mWM.GetInlineDir()); AxisOrientationType blockDimension = BlockDirToAxisOrientation(mWM.GetBlockDir()); // Determine main axis: switch (flexDirection) { case NS_STYLE_FLEX_DIRECTION_ROW: mMainAxis = inlineDimension; mIsRowOriented = true; mIsMainAxisReversed = false; break; case NS_STYLE_FLEX_DIRECTION_ROW_REVERSE: mMainAxis = GetReverseAxis(inlineDimension); mIsRowOriented = true; mIsMainAxisReversed = true; break; case NS_STYLE_FLEX_DIRECTION_COLUMN: mMainAxis = blockDimension; mIsRowOriented = false; mIsMainAxisReversed = false; break; case NS_STYLE_FLEX_DIRECTION_COLUMN_REVERSE: mMainAxis = GetReverseAxis(blockDimension); mIsRowOriented = false; mIsMainAxisReversed = true; break; default: MOZ_ASSERT_UNREACHABLE("Unexpected flex-direction value"); } // Determine cross axis: // (This is set up so that a bogus |flexDirection| value will // give us blockDimension. if (flexDirection == NS_STYLE_FLEX_DIRECTION_COLUMN || flexDirection == NS_STYLE_FLEX_DIRECTION_COLUMN_REVERSE) { mCrossAxis = inlineDimension; } else { mCrossAxis = blockDimension; } // "flex-wrap: wrap-reverse" reverses our cross axis. if (stylePos->mFlexWrap == NS_STYLE_FLEX_WRAP_WRAP_REVERSE) { mCrossAxis = GetReverseAxis(mCrossAxis); mIsCrossAxisReversed = true; } else { mIsCrossAxisReversed = false; } } // Allocates a new FlexLine, adds it to the given LinkedList (at the front or // back depending on aShouldInsertAtFront), and returns a pointer to it. static FlexLine* AddNewFlexLineToList(LinkedList<FlexLine>& aLines, bool aShouldInsertAtFront) { FlexLine* newLine = new FlexLine(); if (aShouldInsertAtFront) { aLines.insertFront(newLine); } else { aLines.insertBack(newLine); } return newLine; } void nsFlexContainerFrame::GenerateFlexLines( nsPresContext* aPresContext, const ReflowInput& aReflowInput, nscoord aContentBoxMainSize, nscoord aAvailableBSizeForContent, const nsTArray<StrutInfo>& aStruts, const FlexboxAxisTracker& aAxisTracker, nsTArray<nsIFrame*>& aPlaceholders, /* out */ LinkedList<FlexLine>& aLines /* out */) { MOZ_ASSERT(aLines.isEmpty(), "Expecting outparam to start out empty"); const bool isSingleLine = NS_STYLE_FLEX_WRAP_NOWRAP == aReflowInput.mStylePosition->mFlexWrap; // If we're transparently reversing axes, then we'll need to link up our // FlexItems and FlexLines in the reverse order, so that the rest of flex // layout (with flipped axes) will still produce the correct result. // Here, we declare a convenience bool that we'll pass when adding a new // FlexLine or FlexItem, to make us insert it at the beginning of its list // (so the list ends up reversed). const bool shouldInsertAtFront = aAxisTracker.AreAxesInternallyReversed(); // We have at least one FlexLine. Even an empty flex container has a single // (empty) flex line. FlexLine* curLine = AddNewFlexLineToList(aLines, shouldInsertAtFront); nscoord wrapThreshold; if (isSingleLine) { // Not wrapping. Set threshold to sentinel value that tells us not to wrap. wrapThreshold = NS_UNCONSTRAINEDSIZE; } else { // Wrapping! Set wrap threshold to flex container's content-box main-size. wrapThreshold = aContentBoxMainSize; // If the flex container doesn't have a definite content-box main-size // (e.g. if main axis is vertical & 'height' is 'auto'), make sure we at // least wrap when we hit its max main-size. if (wrapThreshold == NS_UNCONSTRAINEDSIZE) { const nscoord flexContainerMaxMainSize = GET_MAIN_COMPONENT_LOGICAL(aAxisTracker, aAxisTracker.GetWritingMode(), aReflowInput.ComputedMaxISize(), aReflowInput.ComputedMaxBSize()); wrapThreshold = flexContainerMaxMainSize; } // Also: if we're column-oriented and paginating in the block dimension, // we may need to wrap to a new flex line sooner (before we grow past the // available BSize, potentially running off the end of the page). if (aAxisTracker.IsColumnOriented() && aAvailableBSizeForContent != NS_UNCONSTRAINEDSIZE) { wrapThreshold = std::min(wrapThreshold, aAvailableBSizeForContent); } } // Tracks the index of the next strut, in aStruts (and when this hits // aStruts.Length(), that means there are no more struts): uint32_t nextStrutIdx = 0; // Overall index of the current flex item in the flex container. (This gets // checked against entries in aStruts.) uint32_t itemIdxInContainer = 0; for (nsIFrame* childFrame : mFrames) { // Don't create flex items / lines for placeholder frames: if (childFrame->GetType() == nsGkAtoms::placeholderFrame) { aPlaceholders.AppendElement(childFrame); continue; } // Honor "page-break-before", if we're multi-line and this line isn't empty: if (!isSingleLine && !curLine->IsEmpty() && childFrame->StyleDisplay()->mBreakBefore) { curLine = AddNewFlexLineToList(aLines, shouldInsertAtFront); } UniquePtr<FlexItem> item; if (nextStrutIdx < aStruts.Length() && aStruts[nextStrutIdx].mItemIdx == itemIdxInContainer) { // Use the simplified "strut" FlexItem constructor: item = MakeUnique<FlexItem>(childFrame, aStruts[nextStrutIdx].mStrutCrossSize, aReflowInput.GetWritingMode()); nextStrutIdx++; } else { item = GenerateFlexItemForChild(aPresContext, childFrame, aReflowInput, aAxisTracker); } nscoord itemInnerHypotheticalMainSize = item->GetMainSize(); nscoord itemOuterHypotheticalMainSize = item->GetOuterMainSize(aAxisTracker.GetMainAxis()); // Check if we need to wrap |item| to a new line // (i.e. check if its outer hypothetical main size pushes our line over // the threshold) if (wrapThreshold != NS_UNCONSTRAINEDSIZE && !curLine->IsEmpty() && // No need to wrap at start of a line. wrapThreshold < (curLine->GetTotalOuterHypotheticalMainSize() + itemOuterHypotheticalMainSize)) { curLine = AddNewFlexLineToList(aLines, shouldInsertAtFront); } // Add item to current flex line (and update the line's bookkeeping about // how large its items collectively are). curLine->AddItem(item.release(), shouldInsertAtFront, itemInnerHypotheticalMainSize, itemOuterHypotheticalMainSize); // Honor "page-break-after", if we're multi-line and have more children: if (!isSingleLine && childFrame->GetNextSibling() && childFrame->StyleDisplay()->mBreakAfter) { curLine = AddNewFlexLineToList(aLines, shouldInsertAtFront); } itemIdxInContainer++; } } // Retrieves the content-box main-size of our flex container from the // reflow state (specifically, the main-size of *this continuation* of the // flex container). nscoord nsFlexContainerFrame::GetMainSizeFromReflowInput( const ReflowInput& aReflowInput, const FlexboxAxisTracker& aAxisTracker) { if (aAxisTracker.IsRowOriented()) { // Row-oriented --> our main axis is the inline axis, so our main size // is our inline size (which should already be resolved). NS_WARNING_ASSERTION( aReflowInput.ComputedISize() != NS_UNCONSTRAINEDSIZE, "Unconstrained inline size; this should only result from huge sizes " "(not intrinsic sizing w/ orthogonal flows)"); return aReflowInput.ComputedISize(); } // Note: This may be unconstrained, if our block size is "auto": return GetEffectiveComputedBSize(aReflowInput); } // Returns the largest outer hypothetical main-size of any line in |aLines|. // (i.e. the hypothetical main-size of the largest line) static nscoord GetLargestLineMainSize(const FlexLine* aFirstLine) { nscoord largestLineOuterSize = 0; for (const FlexLine* line = aFirstLine; line; line = line->getNext()) { largestLineOuterSize = std::max(largestLineOuterSize, line->GetTotalOuterHypotheticalMainSize()); } return largestLineOuterSize; } /* Resolves the content-box main-size of a flex container frame, * primarily based on: * - the "tentative" main size, taken from the reflow state ("tentative" * because it may be unconstrained or may run off the page). * - the available BSize (needed if the main axis is the block axis). * - the sizes of our lines of flex items. * * Guaranteed to return a definite length, i.e. not NS_UNCONSTRAINEDSIZE, * aside from cases with huge lengths which happen to compute to that value. * * (Note: This function should be structurally similar to 'ComputeCrossSize()', * except that here, the caller has already grabbed the tentative size from the * reflow state.) */ static nscoord ResolveFlexContainerMainSize(const ReflowInput& aReflowInput, const FlexboxAxisTracker& aAxisTracker, nscoord aTentativeMainSize, nscoord aAvailableBSizeForContent, const FlexLine* aFirstLine, nsReflowStatus& aStatus) { MOZ_ASSERT(aFirstLine, "null first line pointer"); if (aAxisTracker.IsRowOriented()) { // Row-oriented --> our main axis is the inline axis, so our main size // is our inline size (which should already be resolved). return aTentativeMainSize; } if (aTentativeMainSize != NS_INTRINSICSIZE) { // Column-oriented case, with fixed BSize: if (aAvailableBSizeForContent == NS_UNCONSTRAINEDSIZE || aTentativeMainSize < aAvailableBSizeForContent) { // Not in a fragmenting context, OR no need to fragment because we have // more available BSize than we need. Either way, we don't need to clamp. // (Note that the reflow state has already done the appropriate // min/max-BSize clamping.) return aTentativeMainSize; } // Fragmenting *and* our fixed BSize is larger than available BSize: // Mark incomplete so we get a next-in-flow, and take up all of the // available BSize (or the amount of BSize required by our children, if // that's larger; but of course not more than our own computed BSize). // XXXdholbert For now, we don't support pushing children to our next // continuation or splitting children, so "amount of BSize required by // our children" is just the main-size (BSize) of our longest flex line. NS_FRAME_SET_INCOMPLETE(aStatus); nscoord largestLineOuterSize = GetLargestLineMainSize(aFirstLine); if (largestLineOuterSize <= aAvailableBSizeForContent) { return aAvailableBSizeForContent; } return std::min(aTentativeMainSize, largestLineOuterSize); } // Column-oriented case, with auto BSize: // Resolve auto BSize to the largest FlexLine length, clamped to our // computed min/max main-size properties. // XXXdholbert Handle constrained-aAvailableBSizeForContent case here. nscoord largestLineOuterSize = GetLargestLineMainSize(aFirstLine); return NS_CSS_MINMAX(largestLineOuterSize, aReflowInput.ComputedMinBSize(), aReflowInput.ComputedMaxBSize()); } nscoord nsFlexContainerFrame::ComputeCrossSize(const ReflowInput& aReflowInput, const FlexboxAxisTracker& aAxisTracker, nscoord aSumLineCrossSizes, nscoord aAvailableBSizeForContent, bool* aIsDefinite, nsReflowStatus& aStatus) { MOZ_ASSERT(aIsDefinite, "outparam pointer must be non-null"); if (aAxisTracker.IsColumnOriented()) { // Column-oriented --> our cross axis is the inline axis, so our cross size // is our inline size (which should already be resolved). NS_WARNING_ASSERTION( aReflowInput.ComputedISize() != NS_UNCONSTRAINEDSIZE, "Unconstrained inline size; this should only result from huge sizes " "(not intrinsic sizing w/ orthogonal flows)"); *aIsDefinite = true; return aReflowInput.ComputedISize(); } nscoord effectiveComputedBSize = GetEffectiveComputedBSize(aReflowInput); if (effectiveComputedBSize != NS_INTRINSICSIZE) { // Row-oriented case (cross axis is block-axis), with fixed BSize: *aIsDefinite = true; if (aAvailableBSizeForContent == NS_UNCONSTRAINEDSIZE || effectiveComputedBSize < aAvailableBSizeForContent) { // Not in a fragmenting context, OR no need to fragment because we have // more available BSize than we need. Either way, just use our fixed // BSize. (Note that the reflow state has already done the appropriate // min/max-BSize clamping.) return effectiveComputedBSize; } // Fragmenting *and* our fixed BSize is too tall for available BSize: // Mark incomplete so we get a next-in-flow, and take up all of the // available BSize (or the amount of BSize required by our children, if // that's larger; but of course not more than our own computed BSize). // XXXdholbert For now, we don't support pushing children to our next // continuation or splitting children, so "amount of BSize required by // our children" is just the sum of our FlexLines' BSizes (cross sizes). NS_FRAME_SET_INCOMPLETE(aStatus); if (aSumLineCrossSizes <= aAvailableBSizeForContent) { return aAvailableBSizeForContent; } return std::min(effectiveComputedBSize, aSumLineCrossSizes); } // Row-oriented case (cross axis is block axis), with auto BSize: // Shrink-wrap our line(s), subject to our min-size / max-size // constraints in that (block) axis. // XXXdholbert Handle constrained-aAvailableBSizeForContent case here. *aIsDefinite = false; return NS_CSS_MINMAX(aSumLineCrossSizes, aReflowInput.ComputedMinBSize(), aReflowInput.ComputedMaxBSize()); } void FlexLine::PositionItemsInMainAxis(uint8_t aJustifyContent, nscoord aContentBoxMainSize, const FlexboxAxisTracker& aAxisTracker) { MainAxisPositionTracker mainAxisPosnTracker(aAxisTracker, this, aJustifyContent, aContentBoxMainSize); for (FlexItem* item = mItems.getFirst(); item; item = item->getNext()) { nscoord itemMainBorderBoxSize = item->GetMainSize() + item->GetBorderPaddingSizeInAxis(mainAxisPosnTracker.GetAxis()); // Resolve any main-axis 'auto' margins on aChild to an actual value. mainAxisPosnTracker.ResolveAutoMarginsInMainAxis(*item); // Advance our position tracker to child's upper-left content-box corner, // and use that as its position in the main axis. mainAxisPosnTracker.EnterMargin(item->GetMargin()); mainAxisPosnTracker.EnterChildFrame(itemMainBorderBoxSize); item->SetMainPosition(mainAxisPosnTracker.GetPosition()); mainAxisPosnTracker.ExitChildFrame(itemMainBorderBoxSize); mainAxisPosnTracker.ExitMargin(item->GetMargin()); mainAxisPosnTracker.TraversePackingSpace(); } } /** * Given the flex container's "flex-relative ascent" (i.e. distance from the * flex container's content-box cross-start edge to its baseline), returns * its actual physical ascent value (the distance from the *border-box* top * edge to its baseline). */ static nscoord ComputePhysicalAscentFromFlexRelativeAscent( nscoord aFlexRelativeAscent, nscoord aContentBoxCrossSize, const ReflowInput& aReflowInput, const FlexboxAxisTracker& aAxisTracker) { return aReflowInput.ComputedPhysicalBorderPadding().top + PhysicalCoordFromFlexRelativeCoord(aFlexRelativeAscent, aContentBoxCrossSize, aAxisTracker.GetCrossAxis()); } void nsFlexContainerFrame::SizeItemInCrossAxis( nsPresContext* aPresContext, const FlexboxAxisTracker& aAxisTracker, ReflowInput& aChildReflowInput, FlexItem& aItem) { if (aAxisTracker.IsCrossAxisHorizontal()) { MOZ_ASSERT(aItem.HasIntrinsicRatio(), "For now, caller's CanMainSizeInfluenceCrossSize check should " "only allow us to get here for items with intrinsic ratio"); // XXXdholbert When we finish support for vertical writing-modes, // (in bug 1079155 or a dependency), we'll relax the horizontal check in // CanMainSizeInfluenceCrossSize, and this function will need to be able // to measure the baseline & width (given our resolved height) // of vertical-writing-mode flex items here. // For now, we only expect to get here for items with an intrinsic aspect // ratio; and for those items, we can just read the size off of the reflow // state, without performing reflow. aItem.SetCrossSize(aChildReflowInput.ComputedWidth()); return; } MOZ_ASSERT(!aItem.HadMeasuringReflow(), "We shouldn't need more than one measuring reflow"); if (aItem.GetAlignSelf() == NS_STYLE_ALIGN_STRETCH) { // This item's got "align-self: stretch", so we probably imposed a // stretched computed height on it during its previous reflow. We're // not imposing that height for *this* measuring reflow, so we need to // tell it to treat this reflow as a vertical resize (regardless of // whether any of its ancestors are being resized). aChildReflowInput.SetVResize(true); } ReflowOutput childDesiredSize(aChildReflowInput); nsReflowStatus childReflowStatus; const uint32_t flags = NS_FRAME_NO_MOVE_FRAME; ReflowChild(aItem.Frame(), aPresContext, childDesiredSize, aChildReflowInput, 0, 0, flags, childReflowStatus); aItem.SetHadMeasuringReflow(); // XXXdholbert Once we do pagination / splitting, we'll need to actually // handle incomplete childReflowStatuses. But for now, we give our kids // unconstrained available height, which means they should always complete. MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus), "We gave flex item unconstrained available height, so it " "should be complete"); // Tell the child we're done with its initial reflow. // (Necessary for e.g. GetBaseline() to work below w/out asserting) FinishReflowChild(aItem.Frame(), aPresContext, childDesiredSize, &aChildReflowInput, 0, 0, flags); // Save the sizing info that we learned from this reflow // ----------------------------------------------------- // Tentatively store the child's desired content-box cross-size. // Note that childDesiredSize is the border-box size, so we have to // subtract border & padding to get the content-box size. // (Note that at this point in the code, we know our cross axis is vertical, // so we don't bother with making aAxisTracker pick the cross-axis component // for us.) nscoord crossAxisBorderPadding = aItem.GetBorderPadding().TopBottom(); if (childDesiredSize.Height() < crossAxisBorderPadding) { // Child's requested size isn't large enough for its border/padding! // This is OK for the trivial nsFrame::Reflow() impl, but other frame // classes should know better. So, if we get here, the child had better be // an instance of nsFrame (i.e. it should return null from GetType()). // XXXdholbert Once we've fixed bug 765861, we should upgrade this to an // assertion that trivially passes if bug 765861's flag has been flipped. NS_WARNING_ASSERTION( !aItem.Frame()->GetType(), "Child should at least request space for border/padding"); aItem.SetCrossSize(0); } else { // (normal case) aItem.SetCrossSize(childDesiredSize.Height() - crossAxisBorderPadding); } aItem.SetAscent(childDesiredSize.BlockStartAscent()); } void FlexLine::PositionItemsInCrossAxis(nscoord aLineStartPosition, const FlexboxAxisTracker& aAxisTracker) { SingleLineCrossAxisPositionTracker lineCrossAxisPosnTracker(aAxisTracker); for (FlexItem* item = mItems.getFirst(); item; item = item->getNext()) { // First, stretch the item's cross size (if appropriate), and resolve any // auto margins in this axis. item->ResolveStretchedCrossSize(mLineCrossSize, aAxisTracker); lineCrossAxisPosnTracker.ResolveAutoMarginsInCrossAxis(*this, *item); // Compute the cross-axis position of this item nscoord itemCrossBorderBoxSize = item->GetCrossSize() + item->GetBorderPaddingSizeInAxis(aAxisTracker.GetCrossAxis()); lineCrossAxisPosnTracker.EnterAlignPackingSpace(*this, *item, aAxisTracker); lineCrossAxisPosnTracker.EnterMargin(item->GetMargin()); lineCrossAxisPosnTracker.EnterChildFrame(itemCrossBorderBoxSize); item->SetCrossPosition(aLineStartPosition + lineCrossAxisPosnTracker.GetPosition()); // Back out to cross-axis edge of the line. lineCrossAxisPosnTracker.ResetPosition(); } } void nsFlexContainerFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize, const ReflowInput& aReflowInput, nsReflowStatus& aStatus) { MarkInReflow(); DO_GLOBAL_REFLOW_COUNT("nsFlexContainerFrame"); DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus); MOZ_LOG(gFlexContainerLog, LogLevel::Debug, ("Reflow() for nsFlexContainerFrame %p\n", this)); if (IsFrameTreeTooDeep(aReflowInput, aDesiredSize, aStatus)) { return; } // We (and our children) can only depend on our ancestor's bsize if we have // a percent-bsize, or if we're positioned and we have "block-start" and "block-end" // set and have block-size:auto. (There are actually other cases, too -- e.g. if // our parent is itself a block-dir flex container and we're flexible -- but // we'll let our ancestors handle those sorts of cases.) WritingMode wm = aReflowInput.GetWritingMode(); const nsStylePosition* stylePos = StylePosition(); const nsStyleCoord& bsize = stylePos->BSize(wm); if (bsize.HasPercent() || (StyleDisplay()->IsAbsolutelyPositionedStyle() && eStyleUnit_Auto == bsize.GetUnit() && eStyleUnit_Auto != stylePos->mOffset.GetBStartUnit(wm) && eStyleUnit_Auto != stylePos->mOffset.GetBEndUnit(wm))) { AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE); } // If we've never reordered our children, then we can trust that they're // already in DOM-order, and we only need to consider their "order" property // when checking them for sortedness & sorting them. // // After we actually sort them, though, we can't trust that they're in DOM // order anymore. So, from that point on, our sort & sorted-order-checking // operations need to use a fancier LEQ function that also takes DOM order // into account, so that we can honor the spec's requirement that frames w/ // equal "order" values are laid out in DOM order. if (!HasAnyStateBits(NS_STATE_FLEX_CHILDREN_REORDERED)) { if (SortChildrenIfNeeded<IsOrderLEQ>()) { AddStateBits(NS_STATE_FLEX_CHILDREN_REORDERED); } } else { SortChildrenIfNeeded<IsOrderLEQWithDOMFallback>(); } RenumberList(); const FlexboxAxisTracker axisTracker(this, aReflowInput.GetWritingMode()); // If we're being fragmented into a constrained BSize, then subtract off // borderpadding BStart from that constrained BSize, to get the available // BSize for our content box. (No need to subtract the borderpadding BStart // if we're already skipping it via GetLogicalSkipSides, though.) nscoord availableBSizeForContent = aReflowInput.AvailableBSize(); if (availableBSizeForContent != NS_UNCONSTRAINEDSIZE && !(GetLogicalSkipSides(&aReflowInput).BStart())) { availableBSizeForContent -= aReflowInput.ComputedLogicalBorderPadding().BStart(wm); // (Don't let that push availableBSizeForContent below zero, though): availableBSizeForContent = std::max(availableBSizeForContent, 0); } nscoord contentBoxMainSize = GetMainSizeFromReflowInput(aReflowInput, axisTracker); AutoTArray<StrutInfo, 1> struts; DoFlexLayout(aPresContext, aDesiredSize, aReflowInput, aStatus, contentBoxMainSize, availableBSizeForContent, struts, axisTracker); if (!struts.IsEmpty()) { // We're restarting flex layout, with new knowledge of collapsed items. DoFlexLayout(aPresContext, aDesiredSize, aReflowInput, aStatus, contentBoxMainSize, availableBSizeForContent, struts, axisTracker); } } // RAII class to clean up a list of FlexLines. // Specifically, this removes each line from the list, deletes all the // FlexItems in its list, and deletes the FlexLine. class MOZ_RAII AutoFlexLineListClearer { public: explicit AutoFlexLineListClearer(LinkedList<FlexLine>& aLines MOZ_GUARD_OBJECT_NOTIFIER_PARAM) : mLines(aLines) { MOZ_GUARD_OBJECT_NOTIFIER_INIT; } ~AutoFlexLineListClearer() { while (FlexLine* line = mLines.popFirst()) { while (FlexItem* item = line->mItems.popFirst()) { delete item; } delete line; } } private: LinkedList<FlexLine>& mLines; MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER }; // Class to let us temporarily provide an override value for the the main-size // CSS property ('width' or 'height') on a flex item, for use in // nsFrame::ComputeSizeWithIntrinsicDimensions. // (We could use this overridden size more broadly, too, but it's probably // better to avoid property-table accesses. So, where possible, we communicate // the resolved main-size to the child via modifying its reflow state directly, // instead of using this class.) class MOZ_RAII AutoFlexItemMainSizeOverride final { public: explicit AutoFlexItemMainSizeOverride(FlexItem& aItem MOZ_GUARD_OBJECT_NOTIFIER_PARAM) : mItemProps(aItem.Frame()->Properties()) { MOZ_GUARD_OBJECT_NOTIFIER_INIT; MOZ_ASSERT(!mItemProps.Has(nsIFrame::FlexItemMainSizeOverride()), "FlexItemMainSizeOverride prop shouldn't be set already; " "it should only be set temporarily (& not recursively)"); NS_ASSERTION(aItem.HasIntrinsicRatio(), "This should only be needed for items with an aspect ratio"); mItemProps.Set(nsIFrame::FlexItemMainSizeOverride(), aItem.GetMainSize()); } ~AutoFlexItemMainSizeOverride() { mItemProps.Remove(nsIFrame::FlexItemMainSizeOverride()); } private: const FrameProperties mItemProps; MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER }; void nsFlexContainerFrame::CalculatePackingSpace(uint32_t aNumThingsToPack, uint8_t aAlignVal, nscoord* aFirstSubjectOffset, uint32_t* aNumPackingSpacesRemaining, nscoord* aPackingSpaceRemaining) { MOZ_ASSERT(NS_STYLE_ALIGN_SPACE_BETWEEN == NS_STYLE_JUSTIFY_SPACE_BETWEEN && NS_STYLE_ALIGN_SPACE_AROUND == NS_STYLE_JUSTIFY_SPACE_AROUND && NS_STYLE_ALIGN_SPACE_EVENLY == NS_STYLE_JUSTIFY_SPACE_EVENLY, "CalculatePackingSpace assumes that NS_STYLE_ALIGN_SPACE and " "NS_STYLE_JUSTIFY_SPACE constants are interchangeable"); MOZ_ASSERT(aAlignVal == NS_STYLE_ALIGN_SPACE_BETWEEN || aAlignVal == NS_STYLE_ALIGN_SPACE_AROUND || aAlignVal == NS_STYLE_ALIGN_SPACE_EVENLY, "Unexpected alignment value"); MOZ_ASSERT(*aPackingSpaceRemaining >= 0, "Should not be called with negative packing space"); MOZ_ASSERT(aNumThingsToPack >= 1, "Should not be called with less than 1 thing to pack"); // Packing spaces between items: *aNumPackingSpacesRemaining = aNumThingsToPack - 1; if (aAlignVal == NS_STYLE_ALIGN_SPACE_BETWEEN) { // No need to reserve space at beginning/end, so we're done. return; } // We need to add 1 or 2 packing spaces, split between beginning/end, for // space-around / space-evenly: size_t numPackingSpacesForEdges = aAlignVal == NS_STYLE_JUSTIFY_SPACE_AROUND ? 1 : 2; // How big will each "full" packing space be: nscoord packingSpaceSize = *aPackingSpaceRemaining / (*aNumPackingSpacesRemaining + numPackingSpacesForEdges); // How much packing-space are we allocating to the edges: nscoord totalEdgePackingSpace = numPackingSpacesForEdges * packingSpaceSize; // Use half of that edge packing space right now: *aFirstSubjectOffset += totalEdgePackingSpace / 2; // ...but we need to subtract all of it right away, so that we won't // hand out any of it to intermediate packing spaces. *aPackingSpaceRemaining -= totalEdgePackingSpace; } void nsFlexContainerFrame::DoFlexLayout(nsPresContext* aPresContext, ReflowOutput& aDesiredSize, const ReflowInput& aReflowInput, nsReflowStatus& aStatus, nscoord aContentBoxMainSize, nscoord aAvailableBSizeForContent, nsTArray<StrutInfo>& aStruts, const FlexboxAxisTracker& aAxisTracker) { aStatus = NS_FRAME_COMPLETE; LinkedList<FlexLine> lines; nsTArray<nsIFrame*> placeholderKids; AutoFlexLineListClearer cleanupLines(lines); GenerateFlexLines(aPresContext, aReflowInput, aContentBoxMainSize, aAvailableBSizeForContent, aStruts, aAxisTracker, placeholderKids, lines); if (lines.getFirst()->IsEmpty() && !lines.getFirst()->getNext()) { // We have no flex items, our parent should synthesize a baseline if needed. AddStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE); } else { RemoveStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE); } aContentBoxMainSize = ResolveFlexContainerMainSize(aReflowInput, aAxisTracker, aContentBoxMainSize, aAvailableBSizeForContent, lines.getFirst(), aStatus); for (FlexLine* line = lines.getFirst(); line; line = line->getNext()) { line->ResolveFlexibleLengths(aContentBoxMainSize); } // Cross Size Determination - Flexbox spec section 9.4 // =================================================== // Calculate the hypothetical cross size of each item: nscoord sumLineCrossSizes = 0; for (FlexLine* line = lines.getFirst(); line; line = line->getNext()) { for (FlexItem* item = line->GetFirstItem(); item; item = item->getNext()) { // The item may already have the correct cross-size; only recalculate // if the item's main size resolution (flexing) could have influenced it: if (item->CanMainSizeInfluenceCrossSize(aAxisTracker)) { Maybe<AutoFlexItemMainSizeOverride> sizeOverride; if (item->HasIntrinsicRatio()) { // For flex items with an aspect ratio, we have to impose an override // for the main-size property *before* we even instantiate the reflow // state, in order for aspect ratio calculations to produce the right // cross size in the reflow state. (For other flex items, it's OK // (and cheaper) to impose our main size *after* the reflow state has // been constructed, since the main size shouldn't influence anything // about cross-size measurement until we actually reflow the child.) sizeOverride.emplace(*item); } WritingMode wm = item->Frame()->GetWritingMode(); LogicalSize availSize = aReflowInput.ComputedSize(wm); availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE; ReflowInput childReflowInput(aPresContext, aReflowInput, item->Frame(), availSize); if (!sizeOverride) { // Directly override the computed main-size, by tweaking reflow state: if (aAxisTracker.IsMainAxisHorizontal()) { childReflowInput.SetComputedWidth(item->GetMainSize()); } else { childReflowInput.SetComputedHeight(item->GetMainSize()); } } SizeItemInCrossAxis(aPresContext, aAxisTracker, childReflowInput, *item); } } // Now that we've finished with this line's items, size the line itself: line->ComputeCrossSizeAndBaseline(aAxisTracker); sumLineCrossSizes += line->GetLineCrossSize(); } bool isCrossSizeDefinite; const nscoord contentBoxCrossSize = ComputeCrossSize(aReflowInput, aAxisTracker, sumLineCrossSizes, aAvailableBSizeForContent, &isCrossSizeDefinite, aStatus); // Set up state for cross-axis alignment, at a high level (outside the // scope of a particular flex line) CrossAxisPositionTracker crossAxisPosnTracker(lines.getFirst(), aReflowInput, contentBoxCrossSize, isCrossSizeDefinite, aAxisTracker); // Now that we know the cross size of each line (including // "align-content:stretch" adjustments, from the CrossAxisPositionTracker // constructor), we can create struts for any flex items with // "visibility: collapse" (and restart flex layout). if (aStruts.IsEmpty()) { // (Don't make struts if we already did) BuildStrutInfoFromCollapsedItems(lines.getFirst(), aStruts); if (!aStruts.IsEmpty()) { // Restart flex layout, using our struts. return; } } // If the container should derive its baseline from the first FlexLine, // do that here (while crossAxisPosnTracker is conveniently pointing // at the cross-start edge of that line, which the line's baseline offset is // measured from): nscoord flexContainerAscent; if (!aAxisTracker.AreAxesInternallyReversed()) { nscoord firstLineBaselineOffset = lines.getFirst()->GetFirstBaselineOffset(); if (firstLineBaselineOffset == nscoord_MIN) { // No baseline-aligned items in line. Use sentinel value to prompt us to // get baseline from the first FlexItem after we've reflowed it. flexContainerAscent = nscoord_MIN; } else { flexContainerAscent = ComputePhysicalAscentFromFlexRelativeAscent( crossAxisPosnTracker.GetPosition() + firstLineBaselineOffset, contentBoxCrossSize, aReflowInput, aAxisTracker); } } const auto justifyContent = IsLegacyBox(aReflowInput.mFrame) ? ConvertLegacyStyleToJustifyContent(StyleXUL()) : aReflowInput.mStylePosition->mJustifyContent; for (FlexLine* line = lines.getFirst(); line; line = line->getNext()) { // Main-Axis Alignment - Flexbox spec section 9.5 // ============================================== line->PositionItemsInMainAxis(justifyContent, aContentBoxMainSize, aAxisTracker); // Cross-Axis Alignment - Flexbox spec section 9.6 // =============================================== line->PositionItemsInCrossAxis(crossAxisPosnTracker.GetPosition(), aAxisTracker); crossAxisPosnTracker.TraverseLine(*line); crossAxisPosnTracker.TraversePackingSpace(); } // If the container should derive its baseline from the last FlexLine, // do that here (while crossAxisPosnTracker is conveniently pointing // at the cross-end edge of that line, which the line's baseline offset is // measured from): if (aAxisTracker.AreAxesInternallyReversed()) { nscoord lastLineBaselineOffset = lines.getLast()->GetFirstBaselineOffset(); if (lastLineBaselineOffset == nscoord_MIN) { // No baseline-aligned items in line. Use sentinel value to prompt us to // get baseline from the last FlexItem after we've reflowed it. flexContainerAscent = nscoord_MIN; } else { flexContainerAscent = ComputePhysicalAscentFromFlexRelativeAscent( crossAxisPosnTracker.GetPosition() - lastLineBaselineOffset, contentBoxCrossSize, aReflowInput, aAxisTracker); } } // Before giving each child a final reflow, calculate the origin of the // flex container's content box (with respect to its border-box), so that // we can compute our flex item's final positions. WritingMode flexWM = aReflowInput.GetWritingMode(); LogicalMargin containerBP = aReflowInput.ComputedLogicalBorderPadding(); // Unconditionally skip block-end border & padding for now, regardless of // writing-mode/GetLogicalSkipSides. We add it lower down, after we've // established baseline and decided whether bottom border-padding fits (if // we're fragmented). const nscoord blockEndContainerBP = containerBP.BEnd(flexWM); const LogicalSides skipSides = GetLogicalSkipSides(&aReflowInput) | LogicalSides(eLogicalSideBitsBEnd); containerBP.ApplySkipSides(skipSides); const LogicalPoint containerContentBoxOrigin(flexWM, containerBP.IStart(flexWM), containerBP.BStart(flexWM)); // Determine flex container's border-box size (used in positioning children): LogicalSize logSize = aAxisTracker.LogicalSizeFromFlexRelativeSizes(aContentBoxMainSize, contentBoxCrossSize); logSize += aReflowInput.ComputedLogicalBorderPadding().Size(flexWM); nsSize containerSize = logSize.GetPhysicalSize(flexWM); // If the flex container has no baseline-aligned items, it will use this item // (the first item, discounting any under-the-hood reversing that we've done) // to determine its baseline: const FlexItem* const firstItem = aAxisTracker.AreAxesInternallyReversed() ? lines.getLast()->GetLastItem() : lines.getFirst()->GetFirstItem(); // FINAL REFLOW: Give each child frame another chance to reflow, now that // we know its final size and position. for (const FlexLine* line = lines.getFirst(); line; line = line->getNext()) { for (const FlexItem* item = line->GetFirstItem(); item; item = item->getNext()) { LogicalPoint framePos = aAxisTracker.LogicalPointFromFlexRelativePoint( item->GetMainPosition(), item->GetCrossPosition(), aContentBoxMainSize, contentBoxCrossSize); // Adjust framePos to be relative to the container's border-box // (i.e. its frame rect), instead of the container's content-box: framePos += containerContentBoxOrigin; // (Intentionally snapshotting this before ApplyRelativePositioning, to // maybe use for setting the flex container's baseline.) const nscoord itemNormalBPos = framePos.B(flexWM); // Check if we actually need to reflow the item -- if we already reflowed // it with the right size, we can just reposition it as-needed. bool itemNeedsReflow = true; // (Start out assuming the worst.) if (item->HadMeasuringReflow()) { LogicalSize finalFlexItemCBSize = aAxisTracker.LogicalSizeFromFlexRelativeSizes(item->GetMainSize(), item->GetCrossSize()); // We've already reflowed the child once. Was the size we gave it in // that reflow the same as its final (post-flexing/stretching) size? if (finalFlexItemCBSize == LogicalSize(flexWM, item->Frame()->GetContentRectRelativeToSelf().Size())) { // Even if our size hasn't changed, some of our descendants might // care that our bsize is now considered "definite" (whereas it // wasn't in our previous "measuring" reflow), if they have a // relative bsize. if (!(item->Frame()->GetStateBits() & NS_FRAME_CONTAINS_RELATIVE_BSIZE)) { // Item has the correct size (and its children don't care that // it's now "definite"). Let's just make sure it's at the right // position. itemNeedsReflow = false; MoveFlexItemToFinalPosition(aReflowInput, *item, framePos, containerSize); } } } if (itemNeedsReflow) { ReflowFlexItem(aPresContext, aAxisTracker, aReflowInput, *item, framePos, containerSize); } // If this is our first item and we haven't established a baseline for // the container yet (i.e. if we don't have 'align-self: baseline' on any // children), then use this child's first baseline as the container's // baseline. if (item == firstItem && flexContainerAscent == nscoord_MIN) { flexContainerAscent = itemNormalBPos + item->ResolvedAscent(true); } } } if (!placeholderKids.IsEmpty()) { ReflowPlaceholders(aPresContext, aReflowInput, placeholderKids, containerContentBoxOrigin, containerSize); } // Compute flex container's desired size (in its own writing-mode), // starting w/ content-box size & growing from there: LogicalSize desiredSizeInFlexWM = aAxisTracker.LogicalSizeFromFlexRelativeSizes(aContentBoxMainSize, contentBoxCrossSize); // Add border/padding (w/ skipSides already applied): desiredSizeInFlexWM.ISize(flexWM) += containerBP.IStartEnd(flexWM); desiredSizeInFlexWM.BSize(flexWM) += containerBP.BStartEnd(flexWM); if (flexContainerAscent == nscoord_MIN) { // Still don't have our baseline set -- this happens if we have no // children (or if our children are huge enough that they have nscoord_MIN // as their baseline... in which case, we'll use the wrong baseline, but no // big deal) NS_WARNING_ASSERTION( lines.getFirst()->IsEmpty(), "Have flex items but didn't get an ascent - that's odd (or there are " "just gigantic sizes involved)"); // Per spec, synthesize baseline from the flex container's content box // (i.e. use block-end side of content-box) // XXXdholbert This only makes sense if parent's writing mode is // horizontal (& even then, really we should be using the BSize in terms // of the parent's writing mode, not ours). Clean up in bug 1155322. flexContainerAscent = desiredSizeInFlexWM.BSize(flexWM); } if (HasAnyStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE)) { // This will force our parent to call GetLogicalBaseline, which will // synthesize a margin-box baseline. aDesiredSize.SetBlockStartAscent(ReflowOutput::ASK_FOR_BASELINE); } else { // XXXdholbert flexContainerAscent needs to be in terms of // our parent's writing-mode here. See bug 1155322. aDesiredSize.SetBlockStartAscent(flexContainerAscent); } // Now: If we're complete, add bottom border/padding to desired height (which // we skipped via skipSides) -- unless that pushes us over available height, // in which case we become incomplete (unless we already weren't asking for // any height, in which case we stay complete to avoid looping forever). // NOTE: If we're auto-height, we allow our bottom border/padding to push us // over the available height without requesting a continuation, for // consistency with the behavior of "display:block" elements. if (NS_FRAME_IS_COMPLETE(aStatus)) { nscoord desiredBSizeWithBEndBP = desiredSizeInFlexWM.BSize(flexWM) + blockEndContainerBP; if (aReflowInput.AvailableBSize() == NS_UNCONSTRAINEDSIZE || desiredSizeInFlexWM.BSize(flexWM) == 0 || desiredBSizeWithBEndBP <= aReflowInput.AvailableBSize() || aReflowInput.ComputedBSize() == NS_INTRINSICSIZE) { // Update desired height to include block-end border/padding desiredSizeInFlexWM.BSize(flexWM) = desiredBSizeWithBEndBP; } else { // We couldn't fit bottom border/padding, so we'll need a continuation. NS_FRAME_SET_INCOMPLETE(aStatus); } } // Calculate the container baselines so that our parent can baseline-align us. mBaselineFromLastReflow = flexContainerAscent; mLastBaselineFromLastReflow = lines.getLast()->GetLastBaselineOffset(); if (mLastBaselineFromLastReflow == nscoord_MIN) { // XXX we fall back to a mirrored first baseline here for now, but this // should probably use the last baseline of the last item or something. mLastBaselineFromLastReflow = desiredSizeInFlexWM.BSize(flexWM) - flexContainerAscent; } // Convert flex container's final desired size to parent's WM, for outparam. aDesiredSize.SetSize(flexWM, desiredSizeInFlexWM); // Overflow area = union(my overflow area, kids' overflow areas) aDesiredSize.SetOverflowAreasToDesiredBounds(); for (nsIFrame* childFrame : mFrames) { ConsiderChildOverflow(aDesiredSize.mOverflowAreas, childFrame); } FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize, aReflowInput, aStatus); NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize) } void nsFlexContainerFrame::MoveFlexItemToFinalPosition( const ReflowInput& aReflowInput, const FlexItem& aItem, LogicalPoint& aFramePos, const nsSize& aContainerSize) { WritingMode outerWM = aReflowInput.GetWritingMode(); // If item is relpos, look up its offsets (cached from prev reflow) LogicalMargin logicalOffsets(outerWM); if (NS_STYLE_POSITION_RELATIVE == aItem.Frame()->StyleDisplay()->mPosition) { FrameProperties props = aItem.Frame()->Properties(); nsMargin* cachedOffsets = props.Get(nsIFrame::ComputedOffsetProperty()); MOZ_ASSERT(cachedOffsets, "relpos previously-reflowed frame should've cached its offsets"); logicalOffsets = LogicalMargin(outerWM, *cachedOffsets); } ReflowInput::ApplyRelativePositioning(aItem.Frame(), outerWM, logicalOffsets, &aFramePos, aContainerSize); aItem.Frame()->SetPosition(outerWM, aFramePos, aContainerSize); PositionFrameView(aItem.Frame()); PositionChildViews(aItem.Frame()); } void nsFlexContainerFrame::ReflowFlexItem(nsPresContext* aPresContext, const FlexboxAxisTracker& aAxisTracker, const ReflowInput& aReflowInput, const FlexItem& aItem, LogicalPoint& aFramePos, const nsSize& aContainerSize) { WritingMode outerWM = aReflowInput.GetWritingMode(); WritingMode wm = aItem.Frame()->GetWritingMode(); LogicalSize availSize = aReflowInput.ComputedSize(wm); availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE; ReflowInput childReflowInput(aPresContext, aReflowInput, aItem.Frame(), availSize); // Keep track of whether we've overriden the child's computed height // and/or width, so we can set its resize flags accordingly. bool didOverrideComputedWidth = false; bool didOverrideComputedHeight = false; // Override computed main-size if (aAxisTracker.IsMainAxisHorizontal()) { childReflowInput.SetComputedWidth(aItem.GetMainSize()); didOverrideComputedWidth = true; } else { childReflowInput.SetComputedHeight(aItem.GetMainSize()); didOverrideComputedHeight = true; } // Override reflow state's computed cross-size if either: // - the item was stretched (in which case we're imposing a cross size) // ...or... // - the item it has an aspect ratio (in which case the cross-size that's // currently in the reflow state is based on arithmetic involving a stale // main-size value that we just stomped on above). (Note that we could handle // this case using an AutoFlexItemMainSizeOverride, as we do elsewhere; but // given that we *already know* the correct cross size to use here, it's // cheaper to just directly set it instead of setting a frame property.) if (aItem.IsStretched() || aItem.HasIntrinsicRatio()) { if (aAxisTracker.IsCrossAxisHorizontal()) { childReflowInput.SetComputedWidth(aItem.GetCrossSize()); didOverrideComputedWidth = true; } else { childReflowInput.SetComputedHeight(aItem.GetCrossSize()); didOverrideComputedHeight = true; } } if (aItem.IsStretched() && !aAxisTracker.IsCrossAxisHorizontal()) { // If this item's height is stretched, it's a relative height. aItem.Frame()->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE); } // XXXdholbert Might need to actually set the correct margins in the // reflow state at some point, so that they can be saved on the frame for // UsedMarginProperty(). Maybe doesn't matter though...? // If we're overriding the computed width or height, *and* we had an // earlier "measuring" reflow, then this upcoming reflow needs to be // treated as a resize. if (aItem.HadMeasuringReflow()) { if (didOverrideComputedWidth) { // (This is somewhat redundant, since the reflow state already // sets mHResize whenever our computed width has changed since the // previous reflow. Still, it's nice for symmetry, and it may become // necessary once we support orthogonal flows.) childReflowInput.SetHResize(true); } if (didOverrideComputedHeight) { childReflowInput.SetVResize(true); } } // NOTE: Be very careful about doing anything else with childReflowInput // after this point, because some of its methods (e.g. SetComputedWidth) // internally call InitResizeFlags and stomp on mVResize & mHResize. ReflowOutput childDesiredSize(childReflowInput); nsReflowStatus childReflowStatus; ReflowChild(aItem.Frame(), aPresContext, childDesiredSize, childReflowInput, outerWM, aFramePos, aContainerSize, 0, childReflowStatus); // XXXdholbert Once we do pagination / splitting, we'll need to actually // handle incomplete childReflowStatuses. But for now, we give our kids // unconstrained available height, which means they should always // complete. MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus), "We gave flex item unconstrained available height, so it " "should be complete"); LogicalMargin offsets = childReflowInput.ComputedLogicalOffsets().ConvertTo(outerWM, wm); ReflowInput::ApplyRelativePositioning(aItem.Frame(), outerWM, offsets, &aFramePos, aContainerSize); FinishReflowChild(aItem.Frame(), aPresContext, childDesiredSize, &childReflowInput, outerWM, aFramePos, aContainerSize, 0); aItem.SetAscent(childDesiredSize.BlockStartAscent()); } void nsFlexContainerFrame::ReflowPlaceholders(nsPresContext* aPresContext, const ReflowInput& aReflowInput, nsTArray<nsIFrame*>& aPlaceholders, const LogicalPoint& aContentBoxOrigin, const nsSize& aContainerSize) { WritingMode outerWM = aReflowInput.GetWritingMode(); // As noted in this method's documentation, we'll reflow every entry in // |aPlaceholders| at the container's content-box origin. for (nsIFrame* placeholder : aPlaceholders) { MOZ_ASSERT(placeholder->GetType() == nsGkAtoms::placeholderFrame, "placeholders array should only contain placeholder frames"); WritingMode wm = placeholder->GetWritingMode(); LogicalSize availSize = aReflowInput.ComputedSize(wm); ReflowInput childReflowInput(aPresContext, aReflowInput, placeholder, availSize); ReflowOutput childDesiredSize(childReflowInput); nsReflowStatus childReflowStatus; ReflowChild(placeholder, aPresContext, childDesiredSize, childReflowInput, outerWM, aContentBoxOrigin, aContainerSize, 0, childReflowStatus); FinishReflowChild(placeholder, aPresContext, childDesiredSize, &childReflowInput, outerWM, aContentBoxOrigin, aContainerSize, 0); // Mark the placeholder frame to indicate that it's not actually at the // element's static position, because we need to apply CSS Alignment after // we determine the OOF's size: placeholder->AddStateBits(PLACEHOLDER_STATICPOS_NEEDS_CSSALIGN); } } /* virtual */ nscoord nsFlexContainerFrame::GetMinISize(nsRenderingContext* aRenderingContext) { nscoord minISize = 0; DISPLAY_MIN_WIDTH(this, minISize); RenumberList(); const nsStylePosition* stylePos = StylePosition(); const FlexboxAxisTracker axisTracker(this, GetWritingMode()); for (nsIFrame* childFrame : mFrames) { nscoord childMinISize = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, childFrame, nsLayoutUtils::MIN_ISIZE); // For a horizontal single-line flex container, the intrinsic min // isize is the sum of its items' min isizes. // For a column-oriented flex container, or for a multi-line row- // oriented flex container, the intrinsic min isize is the max of // its items' min isizes. if (axisTracker.IsRowOriented() && NS_STYLE_FLEX_WRAP_NOWRAP == stylePos->mFlexWrap) { minISize += childMinISize; } else { minISize = std::max(minISize, childMinISize); } } return minISize; } /* virtual */ nscoord nsFlexContainerFrame::GetPrefISize(nsRenderingContext* aRenderingContext) { nscoord prefISize = 0; DISPLAY_PREF_WIDTH(this, prefISize); RenumberList(); // XXXdholbert Optimization: We could cache our intrinsic widths like // nsBlockFrame does (and return it early from this function if it's set). // Whenever anything happens that might change it, set it to // NS_INTRINSIC_WIDTH_UNKNOWN (like nsBlockFrame::MarkIntrinsicISizesDirty // does) const FlexboxAxisTracker axisTracker(this, GetWritingMode()); for (nsIFrame* childFrame : mFrames) { nscoord childPrefISize = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, childFrame, nsLayoutUtils::PREF_ISIZE); if (axisTracker.IsRowOriented()) { prefISize += childPrefISize; } else { prefISize = std::max(prefISize, childPrefISize); } } return prefISize; }