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gecko-dev/layout/generic/nsLineLayout.h

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/* -*- 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/.
* This Original Code has been modified by IBM Corporation. Modifications made by IBM
* described herein are Copyright (c) International Business Machines Corporation, 2000.
* Modifications to Mozilla code or documentation identified per MPL Section 3.3
*
* Date Modified by Description of modification
* 04/20/2000 IBM Corp. OS/2 VisualAge build.
*/
/* state and methods used while laying out a single line of a block frame */
#ifndef nsLineLayout_h___
#define nsLineLayout_h___
#include "nsLineBox.h"
#include "nsBlockReflowState.h"
#include "plarena.h"
#include "gfxTypes.h"
#include "WritingModes.h"
class nsFloatManager;
struct nsStyleText;
class nsLineLayout {
public:
nsLineLayout(nsPresContext* aPresContext,
nsFloatManager* aFloatManager,
const nsHTMLReflowState* aOuterReflowState,
const nsLineList::iterator* aLine);
~nsLineLayout();
void Init(nsBlockReflowState* aState, nscoord aMinLineBSize,
int32_t aLineNumber) {
mBlockRS = aState;
mMinLineBSize = aMinLineBSize;
mLineNumber = aLineNumber;
}
int32_t GetLineNumber() const {
return mLineNumber;
}
void BeginLineReflow(nscoord aICoord, nscoord aBCoord,
nscoord aISize, nscoord aBSize,
bool aImpactedByFloats,
bool aIsTopOfPage,
mozilla::WritingMode aWritingMode,
nscoord aContainerWidth);
void EndLineReflow();
/**
* Called when a float has been placed. This method updates the
* inline frame and span data to account for any change in positions
* due to available space for the line boxes changing.
* @param aX/aY/aWidth/aHeight are the new available
* space rectangle, relative to the containing block.
* @param aFloatFrame the float frame that was placed.
*/
void UpdateBand(const nsRect& aNewAvailableSpace,
nsIFrame* aFloatFrame);
void BeginSpan(nsIFrame* aFrame, const nsHTMLReflowState* aSpanReflowState,
nscoord aLeftEdge, nscoord aRightEdge, nscoord* aBaseline);
// Returns the width of the span
nscoord EndSpan(nsIFrame* aFrame);
int32_t GetCurrentSpanCount() const;
void SplitLineTo(int32_t aNewCount);
bool IsZeroBSize();
// Reflows the frame and returns the reflow status. aPushedFrame is true
// if the frame is pushed to the next line because it doesn't fit.
void ReflowFrame(nsIFrame* aFrame,
nsReflowStatus& aReflowStatus,
nsHTMLReflowMetrics* aMetrics,
bool& aPushedFrame);
void AddBulletFrame(nsIFrame* aFrame, const nsHTMLReflowMetrics& aMetrics);
void RemoveBulletFrame(nsIFrame* aFrame) {
PushFrame(aFrame);
}
void BlockDirAlignLine();
bool TrimTrailingWhiteSpace();
void InlineDirAlignFrames(nsLineBox* aLine, bool aIsLastLine);
/**
* Handle all the relative positioning in the line, compute the
* combined area (== overflow area) for the line, and handle view
* sizing/positioning and the setting of the overflow rect.
*/
void RelativePositionFrames(nsOverflowAreas& aOverflowAreas);
// Support methods for word-wrapping during line reflow
void SetTextJustificationWeights(int32_t aNumSpaces, int32_t aNumLetters) {
mTextJustificationNumSpaces = aNumSpaces;
mTextJustificationNumLetters = aNumLetters;
}
/**
* @return true if so far during reflow no non-empty content has been
* placed in the line (according to nsIFrame::IsEmpty())
*/
bool LineIsEmpty() const
{
return mLineIsEmpty;
}
/**
* @return true if so far during reflow no non-empty leaf content
* (non-collapsed whitespace, replaced element, inline-block, etc) has been
* placed in the line
*/
bool LineAtStart() const
{
return mLineAtStart;
}
bool LineIsBreakable() const;
bool GetLineEndsInBR() const
{
return mLineEndsInBR;
}
void SetLineEndsInBR(bool aOn)
{
mLineEndsInBR = aOn;
}
//----------------------------------------
// Inform the line-layout about the presence of a floating frame
// XXX get rid of this: use get-frame-type?
bool AddFloat(nsIFrame* aFloat, nscoord aAvailableWidth)
{
return mBlockRS->AddFloat(this, aFloat, aAvailableWidth);
}
void SetTrimmableWidth(nscoord aTrimmableWidth) {
mTrimmableWidth = aTrimmableWidth;
}
//----------------------------------------
bool GetFirstLetterStyleOK() const {
return mFirstLetterStyleOK;
}
void SetFirstLetterStyleOK(bool aSetting) {
mFirstLetterStyleOK = aSetting;
}
bool GetInFirstLetter() const {
return mInFirstLetter;
}
void SetInFirstLetter(bool aSetting) {
mInFirstLetter = aSetting;
}
bool GetInFirstLine() const {
return mInFirstLine;
}
void SetInFirstLine(bool aSetting) {
mInFirstLine = aSetting;
}
// Calling this during block reflow ensures that the next line of inlines
// will be marked dirty, if there is one.
void SetDirtyNextLine() {
mDirtyNextLine = true;
}
bool GetDirtyNextLine() {
return mDirtyNextLine;
}
//----------------------------------------
nsPresContext* mPresContext;
/**
* Record where an optional break could have been placed. During line reflow,
* frames containing optional break points (e.g., whitespace in text frames)
* can call SetLastOptionalBreakPosition to record where a break could
* have been made, but wasn't because we decided to place more content on
* the line. For non-text frames, offset 0 means
* before the content, offset INT32_MAX means after the content.
*
* Currently this is used to handle cases where a single word comprises
* multiple frames, and the first frame fits on the line but the whole word
* doesn't. We look back to the last optional break position and
* reflow the whole line again, forcing a break at that position. The last
* optional break position could be in a text frame or else after a frame
* that cannot be part of a text run, so those are the positions we record.
*
* @param aFits set to true if the break position is within the available width.
*
* @param aPriority the priority of the break opportunity. If we are
* prioritizing break opportunities, we will not set a break if we have
* already set a break with a higher priority. @see gfxBreakPriority.
*
* @return true if we are actually reflowing with forced break position and we
* should break here
*/
bool NotifyOptionalBreakPosition(nsIContent* aContent, int32_t aOffset,
bool aFits, gfxBreakPriority aPriority) {
NS_ASSERTION(!aFits || !mNeedBackup,
"Shouldn't be updating the break position with a break that fits after we've already flagged an overrun");
// Remember the last break position that fits; if there was no break that fit,
// just remember the first break
if ((aFits && aPriority >= mLastOptionalBreakPriority) ||
!mLastOptionalBreakContent) {
mLastOptionalBreakContent = aContent;
mLastOptionalBreakContentOffset = aOffset;
mLastOptionalBreakPriority = aPriority;
}
return aContent && mForceBreakContent == aContent &&
mForceBreakContentOffset == aOffset;
}
/**
* Like NotifyOptionalBreakPosition, but here it's OK for mNeedBackup
* to be set, because the caller is merely pruning some saved break position(s)
* that are actually not feasible.
*/
void RestoreSavedBreakPosition(nsIContent* aContent, int32_t aOffset,
gfxBreakPriority aPriority) {
mLastOptionalBreakContent = aContent;
mLastOptionalBreakContentOffset = aOffset;
mLastOptionalBreakPriority = aPriority;
}
/**
* Signal that no backing up will be required after all.
*/
void ClearOptionalBreakPosition() {
mNeedBackup = false;
mLastOptionalBreakContent = nullptr;
mLastOptionalBreakContentOffset = -1;
mLastOptionalBreakPriority = gfxBreakPriority::eNoBreak;
}
// Retrieve last set optional break position. When this returns null, no
// optional break has been recorded (which means that the line can't break yet).
nsIContent* GetLastOptionalBreakPosition(int32_t* aOffset,
gfxBreakPriority* aPriority) {
*aOffset = mLastOptionalBreakContentOffset;
*aPriority = mLastOptionalBreakPriority;
return mLastOptionalBreakContent;
}
/**
* Check whether frames overflowed the available width and CanPlaceFrame
* requested backing up to a saved break position.
*/
bool NeedsBackup() { return mNeedBackup; }
// Line layout may place too much content on a line, overflowing its available
// width. When that happens, if SetLastOptionalBreakPosition has been
// used to record an optional break that wasn't taken, we can reflow the line
// again and force the break to happen at that point (i.e., backtracking
// to the last choice point).
// Record that we want to break at the given content+offset (which
// should have been previously returned by GetLastOptionalBreakPosition
// from another nsLineLayout).
void ForceBreakAtPosition(nsIContent* aContent, int32_t aOffset) {
mForceBreakContent = aContent;
mForceBreakContentOffset = aOffset;
}
bool HaveForcedBreakPosition() { return mForceBreakContent != nullptr; }
int32_t GetForcedBreakPosition(nsIContent* aContent) {
return mForceBreakContent == aContent ? mForceBreakContentOffset : -1;
}
/**
* This can't be null. It usually returns a block frame but may return
* some other kind of frame when inline frames are reflowed in a non-block
* context (e.g. MathML or floating first-letter).
*/
nsIFrame* LineContainerFrame() const { return mBlockReflowState->frame; }
const nsHTMLReflowState* LineContainerRS() const { return mBlockReflowState; }
const nsLineList::iterator* GetLine() const {
return mGotLineBox ? &mLineBox : nullptr;
}
nsLineList::iterator* GetLine() {
return mGotLineBox ? &mLineBox : nullptr;
}
/**
* Returns the accumulated advance width of frames before the current frame
* on the line, plus the line container's left border+padding.
* This is always positive, the advance width is measured from
* the right edge for RTL blocks and from the left edge for LTR blocks.
* In other words, the current frame's distance from the line container's
* start content edge is:
* <code>GetCurrentFrameInlineDistanceFromBlock() - lineContainer->GetUsedBorderAndPadding().left</code>
* Note the use of <code>.left</code> for both LTR and RTL line containers.
*/
nscoord GetCurrentFrameInlineDistanceFromBlock();
protected:
// This state is constant for a given block frame doing line layout
nsFloatManager* mFloatManager;
const nsStyleText* mStyleText; // for the block
const nsHTMLReflowState* mBlockReflowState;
nsIContent* mLastOptionalBreakContent;
nsIContent* mForceBreakContent;
// XXX remove this when landing bug 154892 (splitting absolute positioned frames)
friend class nsInlineFrame;
nsBlockReflowState* mBlockRS;/* XXX hack! */
nsLineList::iterator mLineBox;
// Per-frame data recorded by the line-layout reflow logic. This
// state is the state needed to post-process the line after reflow
// has completed (block-direction alignment, inline-direction alignment,
// justification and relative positioning).
struct PerSpanData;
struct PerFrameData;
friend struct PerSpanData;
friend struct PerFrameData;
struct PerFrameData
{
PerFrameData(mozilla::WritingMode aWritingMode)
: mBounds(aWritingMode)
, mMargin(aWritingMode)
, mBorderPadding(aWritingMode)
, mOffsets(aWritingMode)
{}
// link to next/prev frame in same span
PerFrameData* mNext;
PerFrameData* mPrev;
// pointer to child span data if this is an inline container frame
PerSpanData* mSpan;
// The frame
nsIFrame* mFrame;
// From metrics
nscoord mAscent;
// note that mBounds is a logical rect in the *line*'s writing mode.
// When setting frame coordinates, we have to convert to the frame's
// writing mode
mozilla::LogicalRect mBounds;
nsOverflowAreas mOverflowAreas;
// From reflow-state
mozilla::LogicalMargin mMargin;
mozilla::LogicalMargin mBorderPadding;
mozilla::LogicalMargin mOffsets;
// state for text justification
int32_t mJustificationNumSpaces;
int32_t mJustificationNumLetters;
// Other state we use
uint8_t mBlockDirAlign;
// PerFrameData flags
#define PFD_RELATIVEPOS 0x00000001
#define PFD_ISTEXTFRAME 0x00000002
#define PFD_ISNONEMPTYTEXTFRAME 0x00000004
#define PFD_ISNONWHITESPACETEXTFRAME 0x00000008
#define PFD_ISLETTERFRAME 0x00000010
#define PFD_RECOMPUTEOVERFLOW 0x00000020
#define PFD_ISBULLET 0x00000040
#define PFD_SKIPWHENTRIMMINGWHITESPACE 0x00000080
#define PFD_LASTFLAG PFD_SKIPWHENTRIMMINGWHITESPACE
uint8_t mFlags;
void SetFlag(uint32_t aFlag, bool aValue)
{
NS_ASSERTION(aFlag<=PFD_LASTFLAG, "bad flag");
NS_ASSERTION(aFlag<=UINT8_MAX, "bad flag");
if (aValue) { // set flag
mFlags |= aFlag;
}
else { // unset flag
mFlags &= ~aFlag;
}
}
bool GetFlag(uint32_t aFlag) const
{
NS_ASSERTION(aFlag<=PFD_LASTFLAG, "bad flag");
return !!(mFlags & aFlag);
}
PerFrameData* Last() {
PerFrameData* pfd = this;
while (pfd->mNext) {
pfd = pfd->mNext;
}
return pfd;
}
};
PerFrameData* mFrameFreeList;
struct PerSpanData {
union {
PerSpanData* mParent;
PerSpanData* mNextFreeSpan;
};
PerFrameData* mFrame;
PerFrameData* mFirstFrame;
PerFrameData* mLastFrame;
const nsHTMLReflowState* mReflowState;
bool mNoWrap;
mozilla::WritingMode mWritingMode;
bool mZeroEffectiveSpanBox;
bool mContainsFloat;
bool mHasNonemptyContent;
nscoord mIStart;
nscoord mICoord;
nscoord mIEnd;
nscoord mBStartLeading, mBEndLeading;
nscoord mLogicalBSize;
nscoord mMinBCoord, mMaxBCoord;
nscoord* mBaseline;
void AppendFrame(PerFrameData* pfd) {
if (nullptr == mLastFrame) {
mFirstFrame = pfd;
}
else {
mLastFrame->mNext = pfd;
pfd->mPrev = mLastFrame;
}
mLastFrame = pfd;
}
};
PerSpanData* mSpanFreeList;
PerSpanData* mRootSpan;
PerSpanData* mCurrentSpan;
gfxBreakPriority mLastOptionalBreakPriority;
int32_t mLastOptionalBreakContentOffset;
int32_t mForceBreakContentOffset;
nscoord mMinLineBSize;
// The amount of text indent that we applied to this line, needed for
// max-element-size calculation.
nscoord mTextIndent;
// This state varies during the reflow of a line but is line
// "global" state not span "local" state.
int32_t mLineNumber;
int32_t mTextJustificationNumSpaces;
int32_t mTextJustificationNumLetters;
int32_t mTotalPlacedFrames;
nscoord mBStartEdge;
nscoord mMaxStartBoxBSize;
nscoord mMaxEndBoxBSize;
nscoord mInflationMinFontSize;
// Final computed line-bSize value after BlockDirAlignFrames for
// the block has been called.
nscoord mFinalLineBSize;
// Amount of trimmable whitespace width for the trailing text frame, if any
nscoord mTrimmableWidth;
nscoord mContainerWidth;
bool mFirstLetterStyleOK : 1;
bool mIsTopOfPage : 1;
bool mImpactedByFloats : 1;
bool mLastFloatWasLetterFrame : 1;
bool mLineIsEmpty : 1;
bool mLineEndsInBR : 1;
bool mNeedBackup : 1;
bool mInFirstLine : 1;
bool mGotLineBox : 1;
bool mInFirstLetter : 1;
bool mHasBullet : 1;
bool mDirtyNextLine : 1;
bool mLineAtStart : 1;
int32_t mSpanDepth;
#ifdef DEBUG
int32_t mSpansAllocated, mSpansFreed;
int32_t mFramesAllocated, mFramesFreed;
#endif
PLArenaPool mArena; // Per span and per frame data, 4 byte aligned
/**
* Allocate a PerFrameData from the mArena pool. The allocation is infallible.
*/
PerFrameData* NewPerFrameData(nsIFrame* aFrame);
/**
* Allocate a PerSpanData from the mArena pool. The allocation is infallible.
*/
PerSpanData* NewPerSpanData();
void FreeSpan(PerSpanData* psd);
bool InBlockContext() const {
return mSpanDepth == 0;
}
void PushFrame(nsIFrame* aFrame);
void AllowForStartMargin(PerFrameData* pfd,
nsHTMLReflowState& aReflowState);
bool CanPlaceFrame(PerFrameData* pfd,
bool aNotSafeToBreak,
bool aFrameCanContinueTextRun,
bool aCanRollBackBeforeFrame,
nsHTMLReflowMetrics& aMetrics,
nsReflowStatus& aStatus,
bool* aOptionalBreakAfterFits);
void PlaceFrame(PerFrameData* pfd,
nsHTMLReflowMetrics& aMetrics);
void BlockDirAlignFrames(PerSpanData* psd);
void PlaceStartEndFrames(PerSpanData* psd,
nscoord aDistanceFromStart,
nscoord aLineBSize);
void RelativePositionFrames(PerSpanData* psd, nsOverflowAreas& aOverflowAreas);
bool TrimTrailingWhiteSpaceIn(PerSpanData* psd, nscoord* aDeltaISize);
void ComputeJustificationWeights(PerSpanData* psd, int32_t* numSpaces, int32_t* numLetters);
struct FrameJustificationState {
int32_t mTotalNumSpaces;
int32_t mTotalNumLetters;
nscoord mTotalWidthForSpaces;
nscoord mTotalWidthForLetters;
int32_t mNumSpacesProcessed;
int32_t mNumLettersProcessed;
nscoord mWidthForSpacesProcessed;
nscoord mWidthForLettersProcessed;
};
// Apply justification. The return value is the amount by which the width of
// the span corresponding to aPSD got increased due to justification.
nscoord ApplyFrameJustification(PerSpanData* aPSD,
FrameJustificationState* aState);
#ifdef DEBUG
void DumpPerSpanData(PerSpanData* psd, int32_t aIndent);
#endif
};
#endif /* nsLineLayout_h___ */
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