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Diffstat (limited to 'layout/generic/nsColumnSetFrame.h')
| -rw-r--r-- | layout/generic/nsColumnSetFrame.h | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/layout/generic/nsColumnSetFrame.h b/layout/generic/nsColumnSetFrame.h new file mode 100644 index 000000000..db44183d6 --- /dev/null +++ b/layout/generic/nsColumnSetFrame.h @@ -0,0 +1,229 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef nsColumnSetFrame_h___ +#define nsColumnSetFrame_h___ + +/* rendering object for css3 multi-column layout */ + +#include "mozilla/Attributes.h" +#include "nsContainerFrame.h" +#include "nsIFrameInlines.h" // for methods used by IS_TRUE_OVERFLOW_CONTAINER + +/** + * nsColumnSetFrame implements CSS multi-column layout. + * @note nsColumnSetFrame keeps true overflow containers in the normal flow + * child lists (i.e. the principal and overflow lists). + */ +class nsColumnSetFrame final : public nsContainerFrame +{ +public: + NS_DECL_FRAMEARENA_HELPERS + + explicit nsColumnSetFrame(nsStyleContext* aContext); + + virtual void Reflow(nsPresContext* aPresContext, + ReflowOutput& aDesiredSize, + const ReflowInput& aReflowInput, + nsReflowStatus& aStatus) override; + +#ifdef DEBUG + virtual void SetInitialChildList(ChildListID aListID, + nsFrameList& aChildList) override; + virtual void AppendFrames(ChildListID aListID, + nsFrameList& aFrameList) override; + virtual void InsertFrames(ChildListID aListID, + nsIFrame* aPrevFrame, + nsFrameList& aFrameList) override; + virtual void RemoveFrame(ChildListID aListID, + nsIFrame* aOldFrame) override; +#endif + + virtual nscoord GetMinISize(nsRenderingContext *aRenderingContext) override; + virtual nscoord GetPrefISize(nsRenderingContext *aRenderingContext) override; + + /** + * Retrieve the available height for content of this frame. The available content + * height is the available height for the frame, minus borders and padding. + */ + virtual nscoord GetAvailableContentBSize(const ReflowInput& aReflowInput); + + virtual nsContainerFrame* GetContentInsertionFrame() override { + nsIFrame* frame = PrincipalChildList().FirstChild(); + + // if no children return nullptr + if (!frame) + return nullptr; + + return frame->GetContentInsertionFrame(); + } + + virtual bool IsFrameOfType(uint32_t aFlags) const override + { + return nsContainerFrame::IsFrameOfType(aFlags & + ~(nsIFrame::eCanContainOverflowContainers)); + } + + virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder, + const nsRect& aDirtyRect, + const nsDisplayListSet& aLists) override; + + virtual nsIAtom* GetType() const override; + + virtual void PaintColumnRule(nsRenderingContext* aCtx, + const nsRect& aDirtyRect, + const nsPoint& aPt); + + /** + * Similar to nsBlockFrame::DrainOverflowLines. Locate any columns not + * handled by our prev-in-flow, and any columns sitting on our own + * overflow list, and put them in our primary child list for reflowing. + */ + void DrainOverflowColumns(); + +#ifdef DEBUG_FRAME_DUMP + virtual nsresult GetFrameName(nsAString& aResult) const override { + return MakeFrameName(NS_LITERAL_STRING("ColumnSet"), aResult); + } +#endif + +protected: + nscoord mLastBalanceBSize; + nsReflowStatus mLastFrameStatus; + + /** + * These are the parameters that control the layout of columns. + */ + struct ReflowConfig { + // The number of columns that we want to balance across. If we're not + // balancing, this will be set to INT32_MAX. + int32_t mBalanceColCount; + + // The inline-size of each individual column. + nscoord mColISize; + + // The amount of inline-size that is expected to be left over after all the + // columns and column gaps are laid out. + nscoord mExpectedISizeLeftOver; + + // The width (inline-size) of each column gap. + nscoord mColGap; + + // The maximum bSize of any individual column during a reflow iteration. + // This parameter is set during each iteration of the binary search for + // the best column block-size. + nscoord mColMaxBSize; + + // A boolean controlling whether or not we are balancing. This should be + // equivalent to mBalanceColCount == INT32_MAX. + bool mIsBalancing; + + // The last known column block-size that was 'feasible'. A column bSize is + // feasible if all child content fits within the specified bSize. + nscoord mKnownFeasibleBSize; + + // The last known block-size that was 'infeasible'. A column bSize is + // infeasible if not all child content fits within the specified bSize. + nscoord mKnownInfeasibleBSize; + + // block-size of the column set frame + nscoord mComputedBSize; + + // The block-size "consumed" by previous-in-flows. + // The computed block-size should be equal to the block-size of the element + // (i.e. the computed block-size itself) plus the consumed block-size. + nscoord mConsumedBSize; + }; + + /** + * Some data that is better calculated during reflow + */ + struct ColumnBalanceData { + // The maximum "content block-size" of any column + nscoord mMaxBSize; + // The sum of the "content block-size" for all columns + nscoord mSumBSize; + // The "content block-size" of the last column + nscoord mLastBSize; + // The maximum "content block-size" of all columns that overflowed + // their available block-size + nscoord mMaxOverflowingBSize; + // This flag determines whether the last reflow of children exceeded the + // computed block-size of the column set frame. If so, we set the bSize to + // this maximum allowable bSize, and continue reflow without balancing. + bool mHasExcessBSize; + + void Reset() { + mMaxBSize = mSumBSize = mLastBSize = mMaxOverflowingBSize = 0; + mHasExcessBSize = false; + } + }; + + bool ReflowColumns(ReflowOutput& aDesiredSize, + const ReflowInput& aReflowInput, + nsReflowStatus& aReflowStatus, + ReflowConfig& aConfig, + bool aLastColumnUnbounded, + nsCollapsingMargin* aCarriedOutBEndMargin, + ColumnBalanceData& aColData); + + /** + * The basic reflow strategy is to call this function repeatedly to + * obtain specific parameters that determine the layout of the + * columns. This function will compute those parameters from the CSS + * style. This function will also be responsible for implementing + * the state machine that controls column balancing. + */ + ReflowConfig ChooseColumnStrategy(const ReflowInput& aReflowInput, + bool aForceAuto, nscoord aFeasibleBSize, + nscoord aInfeasibleBSize); + + /** + * Perform the binary search for the best balance height for this column set. + * + * @param aReflowInput The input parameters for the current reflow iteration. + * @param aPresContext The presentation context in which the current reflow + * iteration is occurring. + * @param aConfig The ReflowConfig object associated with this column set + * frame, generated by ChooseColumnStrategy(). + * @param aColData A data structure used to keep track of data needed between + * successive iterations of the balancing process. + * @param aDesiredSize The final output size of the column set frame (output + * of reflow procedure). + * @param aOutMargin The bottom margin of the column set frame that may be + * carried out from reflow (and thus collapsed). + * @param aUnboundedLastColumn A boolean value indicating that the last column + * can be of any height. Used during the first iteration of the + * balancing procedure to measure the height of all content in + * descendant frames of the column set. + * @param aRunWasFeasible An input/output parameter indicating whether or not + * the last iteration of the balancing loop was a feasible height to + * fit all content from descendant frames. + * @param aStatus A final reflow status of the column set frame, passed in as + * an output parameter. + */ + void FindBestBalanceBSize(const ReflowInput& aReflowInput, + nsPresContext* aPresContext, + ReflowConfig& aConfig, + ColumnBalanceData& aColData, + ReflowOutput& aDesiredSize, + nsCollapsingMargin& aOutMargin, + bool& aUnboundedLastColumn, + bool& aRunWasFeasible, + nsReflowStatus& aStatus); + /** + * Reflow column children. Returns true iff the content that was reflowed + * fit into the mColMaxBSize. + */ + bool ReflowChildren(ReflowOutput& aDesiredSize, + const ReflowInput& aReflowInput, + nsReflowStatus& aStatus, + const ReflowConfig& aConfig, + bool aLastColumnUnbounded, + nsCollapsingMargin* aCarriedOutBEndMargin, + ColumnBalanceData& aColData); +}; + +#endif // nsColumnSetFrame_h___ |