/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ // vim:cindent:ts=2:et:sw=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/. */ /* class that manages rules for positioning floats */ #ifndef nsFloatManager_h_ #define nsFloatManager_h_ #include "mozilla/Attributes.h" #include "mozilla/WritingModes.h" #include "nsCoord.h" #include "nsFrameList.h" // for DEBUG_FRAME_DUMP #include "nsIntervalSet.h" #include "nsTArray.h" class nsIPresShell; class nsIFrame; class nsPresContext; namespace mozilla { struct ReflowInput; } // namespace mozilla /** * The available space for content not occupied by floats is divided * into a sequence of rectangles in the block direction. However, we * need to know not only the rectangle, but also whether it was reduced * (from the content rectangle) by floats that actually intruded into * the content rectangle. */ struct nsFlowAreaRect { mozilla::LogicalRect mRect; bool mHasFloats; nsFlowAreaRect(mozilla::WritingMode aWritingMode, nscoord aICoord, nscoord aBCoord, nscoord aISize, nscoord aBSize, bool aHasFloats) : mRect(aWritingMode, aICoord, aBCoord, aISize, aBSize) , mHasFloats(aHasFloats) {} }; #define NS_FLOAT_MANAGER_CACHE_SIZE 4 class nsFloatManager { public: explicit nsFloatManager(nsIPresShell* aPresShell, mozilla::WritingMode aWM); ~nsFloatManager(); void* operator new(size_t aSize) CPP_THROW_NEW; void operator delete(void* aPtr, size_t aSize); static void Shutdown(); /** * Get float region stored on the frame. (Defaults to mRect if it's * not there.) The float region is the area impacted by this float; * the coordinates are relative to the containing block frame. */ static mozilla::LogicalRect GetRegionFor(mozilla::WritingMode aWM, nsIFrame* aFloatFrame, const nsSize& aContainerSize); /** * Calculate the float region for this frame using aMargin and the * frame's mRect. The region includes the margins around the float, * but doesn't include the relative offsets. * Note that if the frame is or has a continuation, aMargin's top * and/or bottom must be zeroed by the caller. */ static mozilla::LogicalRect CalculateRegionFor( mozilla::WritingMode aWM, nsIFrame* aFloatFrame, const mozilla::LogicalMargin& aMargin, const nsSize& aContainerSize); /** * Store the float region on the frame. The region is stored * as a delta against the mRect, so repositioning the frame will * also reposition the float region. */ static void StoreRegionFor(mozilla::WritingMode aWM, nsIFrame* aFloat, const mozilla::LogicalRect& aRegion, const nsSize& aContainerSize); // Structure that stores the current state of a frame manager for // Save/Restore purposes. struct SavedState { explicit SavedState() {} private: uint32_t mFloatInfoCount; nscoord mLineLeft, mBlockStart; bool mPushedLeftFloatPastBreak; bool mPushedRightFloatPastBreak; bool mSplitLeftFloatAcrossBreak; bool mSplitRightFloatAcrossBreak; friend class nsFloatManager; }; /** * Translate the current origin by the specified offsets. This * creates a new local coordinate space relative to the current * coordinate space. */ void Translate(nscoord aLineLeft, nscoord aBlockStart) { mLineLeft += aLineLeft; mBlockStart += aBlockStart; } /** * Returns the current translation from local coordinate space to * world coordinate space. This represents the accumulated calls to * Translate(). */ void GetTranslation(nscoord& aLineLeft, nscoord& aBlockStart) const { aLineLeft = mLineLeft; aBlockStart = mBlockStart; } /** * Get information about the area available to content that flows * around floats. Two different types of space can be requested: * BAND_FROM_POINT: returns the band containing block-dir coordinate * |aBCoord| (though actually with the top truncated to begin at * aBCoord), but up to at most |aBSize| (which may be nscoord_MAX). * This will return the tallest rectangle whose block start is * |aBCoord| and in which there are no changes in what floats are * on the sides of that rectangle, but will limit the block size * of the rectangle to |aBSize|. The inline start and end edges * of the rectangle give the area available for line boxes in that * space. The inline size of this resulting rectangle will not be * negative. * WIDTH_WITHIN_HEIGHT: This returns a rectangle whose block start * is aBCoord and whose block size is exactly aBSize. Its inline * start and end edges give the corresponding edges of the space * that can be used for line boxes *throughout* that space. (It * is possible that more inline space could be used in part of the * space if a float begins or ends in it.) The inline size of the * resulting rectangle can be negative. * * @param aBCoord [in] block-dir coordinate for block start of * available space desired * @param aBSize [in] see above * @param aContentArea [in] an nsRect representing the content area * @param aState [in] If null, use the current state, otherwise, do * computation based only on floats present in the given * saved state. * @return An nsFlowAreaRect whose: * mRect is the resulting rectangle for line boxes. It will not * extend beyond aContentArea's inline bounds, but may be * narrower when floats are present. * mBandHasFloats is whether there are floats at the sides of the * return value including those that do not reduce the line box * inline size at all (because they are entirely in the margins) * * aBCoord and aAvailSpace are positioned relative to the current translation */ enum BandInfoType { BAND_FROM_POINT, WIDTH_WITHIN_HEIGHT }; nsFlowAreaRect GetFlowArea(mozilla::WritingMode aWM, nscoord aBCoord, BandInfoType aInfoType, nscoord aBSize, mozilla::LogicalRect aContentArea, SavedState* aState, const nsSize& aContainerSize) const; /** * Add a float that comes after all floats previously added. Its * block start must be even with or below the top of all previous * floats. * * aMarginRect is relative to the current translation. The caller * must ensure aMarginRect.height >= 0 and aMarginRect.width >= 0. */ nsresult AddFloat(nsIFrame* aFloatFrame, const mozilla::LogicalRect& aMarginRect, mozilla::WritingMode aWM, const nsSize& aContainerSize); /** * Notify that we tried to place a float that could not fit at all and * had to be pushed to the next page/column? (If so, we can't place * any more floats in this page/column because of the rule that the * top of a float cannot be above the top of an earlier float. It * also means that any clear needs to continue to the next column.) */ void SetPushedLeftFloatPastBreak() { mPushedLeftFloatPastBreak = true; } void SetPushedRightFloatPastBreak() { mPushedRightFloatPastBreak = true; } /** * Notify that we split a float, with part of it needing to be pushed * to the next page/column. (This means that any 'clear' needs to * continue to the next page/column.) */ void SetSplitLeftFloatAcrossBreak() { mSplitLeftFloatAcrossBreak = true; } void SetSplitRightFloatAcrossBreak() { mSplitRightFloatAcrossBreak = true; } /** * Remove the regions associated with this floating frame and its * next-sibling list. Some of the frames may never have been added; * we just skip those. This is not fully general; it only works as * long as the N frames to be removed are the last N frames to have * been added; if there's a frame in the middle of them that should * not be removed, YOU LOSE. */ nsresult RemoveTrailingRegions(nsIFrame* aFrameList); bool HasAnyFloats() const { return !mFloats.IsEmpty(); } /** * Methods for dealing with the propagation of float damage during * reflow. */ bool HasFloatDamage() const { return !mFloatDamage.IsEmpty(); } void IncludeInDamage(nscoord aIntervalBegin, nscoord aIntervalEnd) { mFloatDamage.IncludeInterval(aIntervalBegin + mBlockStart, aIntervalEnd + mBlockStart); } bool IntersectsDamage(nscoord aIntervalBegin, nscoord aIntervalEnd) const { return mFloatDamage.Intersects(aIntervalBegin + mBlockStart, aIntervalEnd + mBlockStart); } /** * Saves the current state of the float manager into aState. */ void PushState(SavedState* aState); /** * Restores the float manager to the saved state. * * These states must be managed using stack discipline. PopState can only * be used after PushState has been used to save the state, and it can only * be used once --- although it can be omitted; saved states can be ignored. * States must be popped in the reverse order they were pushed. A * call to PopState invalidates any saved states Pushed after the * state passed to PopState was pushed. */ void PopState(SavedState* aState); /** * Get the block start of the last float placed into the float * manager, to enforce the rule that a float can't be above an earlier * float. Returns the minimum nscoord value if there are no floats. * * The result is relative to the current translation. */ nscoord GetLowestFloatTop() const; /** * Return the coordinate of the lowest float matching aBreakType in * this float manager. Returns aBCoord if there are no matching * floats. * * Both aBCoord and the result are relative to the current translation. */ enum { // Tell ClearFloats not to push to nscoord_MAX when floats have been // pushed to the next page/column. DONT_CLEAR_PUSHED_FLOATS = (1<<0) }; nscoord ClearFloats(nscoord aBCoord, mozilla::StyleClear aBreakType, uint32_t aFlags = 0) const; /** * Checks if clear would pass into the floats' BFC's next-in-flow, * i.e. whether floats affecting this clear have continuations. */ bool ClearContinues(mozilla::StyleClear aBreakType) const; void AssertStateMatches(SavedState *aState) const { NS_ASSERTION(aState->mLineLeft == mLineLeft && aState->mBlockStart == mBlockStart && aState->mPushedLeftFloatPastBreak == mPushedLeftFloatPastBreak && aState->mPushedRightFloatPastBreak == mPushedRightFloatPastBreak && aState->mSplitLeftFloatAcrossBreak == mSplitLeftFloatAcrossBreak && aState->mSplitRightFloatAcrossBreak == mSplitRightFloatAcrossBreak && aState->mFloatInfoCount == mFloats.Length(), "float manager state should match saved state"); } #ifdef DEBUG_FRAME_DUMP /** * Dump the state of the float manager out to a file. */ nsresult List(FILE* out) const; #endif private: struct FloatInfo { nsIFrame *const mFrame; // The lowest block-ends of left/right floats up to and including // this one. nscoord mLeftBEnd, mRightBEnd; FloatInfo(nsIFrame* aFrame, nscoord aLineLeft, nscoord aBStart, nscoord aISize, nscoord aBSize); nscoord LineLeft() const { return mRect.x; } nscoord LineRight() const { return mRect.XMost(); } nscoord ISize() const { return mRect.width; } nscoord BStart() const { return mRect.y; } nscoord BEnd() const { return mRect.YMost(); } nscoord BSize() const { return mRect.height; } bool IsEmpty() const { return mRect.IsEmpty(); } #ifdef NS_BUILD_REFCNT_LOGGING FloatInfo(const FloatInfo& aOther); ~FloatInfo(); #endif // NB! This is really a logical rect in a writing mode suitable for // placing floats, which is not necessarily the actual writing mode // either of the block which created the frame manager or the block // that is calling the frame manager. The inline coordinates are in // the line-relative axis of the frame manager and its block // coordinates are in the frame manager's real block direction. nsRect mRect; }; #ifdef DEBUG mozilla::WritingMode mWritingMode; #endif // Translation from local to global coordinate space. nscoord mLineLeft, mBlockStart; nsTArray<FloatInfo> mFloats; nsIntervalSet mFloatDamage; // Did we try to place a float that could not fit at all and had to be // pushed to the next page/column? If so, we can't place any more // floats in this page/column because of the rule that the top of a // float cannot be above the top of an earlier float. And we also // need to apply this information to 'clear', and thus need to // separate left and right floats. bool mPushedLeftFloatPastBreak; bool mPushedRightFloatPastBreak; // Did we split a float, with part of it needing to be pushed to the // next page/column. This means that any 'clear' needs to continue to // the next page/column. bool mSplitLeftFloatAcrossBreak; bool mSplitRightFloatAcrossBreak; static int32_t sCachedFloatManagerCount; static void* sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE]; nsFloatManager(const nsFloatManager&) = delete; void operator=(const nsFloatManager&) = delete; }; /** * A helper class to manage maintenance of the float manager during * nsBlockFrame::Reflow. It automatically restores the old float * manager in the reflow input when the object goes out of scope. */ class nsAutoFloatManager { using ReflowInput = mozilla::ReflowInput; public: explicit nsAutoFloatManager(ReflowInput& aReflowInput) : mReflowInput(aReflowInput), mNew(nullptr), mOld(nullptr) {} ~nsAutoFloatManager(); /** * Create a new float manager for the specified frame. This will * `remember' the old float manager, and install the new float * manager in the reflow input. */ void CreateFloatManager(nsPresContext *aPresContext); protected: ReflowInput &mReflowInput; nsFloatManager *mNew; nsFloatManager *mOld; }; #endif /* !defined(nsFloatManager_h_) */