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gecko/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:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Steve Clark <buster@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK *****
* 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 "nsFrame.h"
#include "nsDeque.h"
#include "nsLineBox.h"
#include "nsBlockReflowState.h"
#include "plarena.h"
#include "gfxTypes.h"
class nsBlockFrame;
class nsFloatManager;
class nsPlaceholderFrame;
struct nsStyleText;
class nsLineLayout {
public:
nsLineLayout(nsPresContext* aPresContext,
nsFloatManager* aFloatManager,
const nsHTMLReflowState* aOuterReflowState,
const nsLineList::iterator* aLine);
~nsLineLayout();
void Init(nsBlockReflowState* aState, nscoord aMinLineHeight,
PRInt32 aLineNumber) {
mBlockRS = aState;
mMinLineHeight = aMinLineHeight;
mLineNumber = aLineNumber;
}
PRInt32 GetLineNumber() const {
return mLineNumber;
}
void BeginLineReflow(nscoord aX, nscoord aY,
nscoord aWidth, nscoord aHeight,
PRBool aImpactedByFloats,
PRBool aIsTopOfPage);
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);
nsresult BeginSpan(nsIFrame* aFrame,
const nsHTMLReflowState* aSpanReflowState,
nscoord aLeftEdge,
nscoord aRightEdge);
// Returns the width of the span
nscoord EndSpan(nsIFrame* aFrame);
PRInt32 GetCurrentSpanCount() const;
void SplitLineTo(PRInt32 aNewCount);
PRBool IsZeroHeight();
// Reflows the frame and returns the reflow status. aPushedFrame is PR_TRUE
// if the frame is pushed to the next line because it doesn't fit
nsresult ReflowFrame(nsIFrame* aFrame,
nsReflowStatus& aReflowStatus,
nsHTMLReflowMetrics* aMetrics,
PRBool& aPushedFrame);
nsresult AddBulletFrame(nsIFrame* aFrame,
const nsHTMLReflowMetrics& aMetrics);
void RemoveBulletFrame(nsIFrame* aFrame) {
PushFrame(aFrame);
}
void VerticalAlignLine();
PRBool TrimTrailingWhiteSpace();
void HorizontalAlignFrames(nsRect& aLineBounds, PRBool aAllowJustify);
/**
* 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);
//----------------------------------------
// Supporting methods and data for flags
protected:
#define LL_FIRSTLETTERSTYLEOK 0x00000008
#define LL_ISTOPOFPAGE 0x00000010
#define LL_IMPACTEDBYFLOATS 0x00000040
#define LL_LASTFLOATWASLETTERFRAME 0x00000080
#define LL_LINEISEMPTY 0x00000100
#define LL_LINEENDSINBR 0x00000200
#define LL_NEEDBACKUP 0x00000400
#define LL_INFIRSTLINE 0x00000800
#define LL_GOTLINEBOX 0x00001000
#define LL_INFIRSTLETTER 0x00002000
#define LL_HASBULLET 0x00004000
#define LL_DIRTYNEXTLINE 0x00008000
#define LL_LINEATSTART 0x00010000
#define LL_LASTFLAG LL_LINEATSTART
void SetFlag(PRUint32 aFlag, PRBool aValue)
{
NS_ASSERTION(aFlag<=LL_LASTFLAG, "bad flag");
NS_ASSERTION(aValue==PR_FALSE || aValue==PR_TRUE, "bad value");
if (aValue) { // set flag
mFlags |= aFlag;
}
else { // unset flag
mFlags &= ~aFlag;
}
}
PRBool GetFlag(PRUint32 aFlag) const
{
NS_ASSERTION(aFlag<=LL_LASTFLAG, "bad flag");
return !!(mFlags & aFlag);
}
public:
// Support methods for word-wrapping during line reflow
void SetTextJustificationWeights(PRInt32 aNumSpaces, PRInt32 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())
*/
PRBool LineIsEmpty() const
{
return GetFlag(LL_LINEISEMPTY);
}
/**
* @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
*/
PRBool LineAtStart() const
{
return GetFlag(LL_LINEATSTART);
}
PRBool LineIsBreakable() const;
PRBool GetLineEndsInBR() const
{
return GetFlag(LL_LINEENDSINBR);
}
void SetLineEndsInBR(PRBool aOn)
{
SetFlag(LL_LINEENDSINBR, aOn);
}
//----------------------------------------
// Inform the line-layout about the presence of a floating frame
// XXX get rid of this: use get-frame-type?
PRBool AddFloat(nsIFrame* aFloat, nscoord aAvailableWidth)
{
return mBlockRS->AddFloat(this, aFloat, aAvailableWidth);
}
void SetTrimmableWidth(nscoord aTrimmableWidth) {
mTrimmableWidth = aTrimmableWidth;
}
//----------------------------------------
PRBool GetFirstLetterStyleOK() const {
return GetFlag(LL_FIRSTLETTERSTYLEOK);
}
void SetFirstLetterStyleOK(PRBool aSetting) {
SetFlag(LL_FIRSTLETTERSTYLEOK, aSetting);
}
PRBool GetInFirstLetter() const {
return GetFlag(LL_INFIRSTLETTER);
}
void SetInFirstLetter(PRBool aSetting) {
SetFlag(LL_INFIRSTLETTER, aSetting);
}
PRBool GetInFirstLine() const {
return GetFlag(LL_INFIRSTLINE);
}
void SetInFirstLine(PRBool aSetting) {
SetFlag(LL_INFIRSTLINE, aSetting);
}
// Calling this during block reflow ensures that the next line of inlines
// will be marked dirty, if there is one.
void SetDirtyNextLine() {
SetFlag(LL_DIRTYNEXTLINE, PR_TRUE);
}
PRBool GetDirtyNextLine() {
return GetFlag(LL_DIRTYNEXTLINE);
}
//----------------------------------------
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 PR_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 PR_TRUE if we are actually reflowing with forced break position and we
* should break here
*/
PRBool NotifyOptionalBreakPosition(nsIContent* aContent, PRInt32 aOffset,
PRBool aFits, gfxBreakPriority aPriority) {
NS_ASSERTION(!aFits || !GetFlag(LL_NEEDBACKUP),
"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 LL_NEEDBACKUP
* to be set, because the caller is merely pruning some saved break position(s)
* that are actually not feasible.
*/
void RestoreSavedBreakPosition(nsIContent* aContent, PRInt32 aOffset,
gfxBreakPriority aPriority) {
mLastOptionalBreakContent = aContent;
mLastOptionalBreakContentOffset = aOffset;
mLastOptionalBreakPriority = aPriority;
}
/**
* Signal that no backing up will be required after all.
*/
void ClearOptionalBreakPosition() {
SetFlag(LL_NEEDBACKUP, PR_FALSE);
mLastOptionalBreakContent = nsnull;
mLastOptionalBreakContentOffset = -1;
mLastOptionalBreakPriority = 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(PRInt32* 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.
*/
PRBool NeedsBackup() { return GetFlag(LL_NEEDBACKUP); }
// 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, PRInt32 aOffset) {
mForceBreakContent = aContent;
mForceBreakContentOffset = aOffset;
}
PRBool HaveForcedBreakPosition() { return mForceBreakContent != nsnull; }
PRInt32 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* GetLineContainerFrame() const { return mBlockReflowState->frame; }
const nsLineList::iterator* GetLine() const {
return GetFlag(LL_GOTLINEBOX) ? &mLineBox : nsnull;
}
nsLineList::iterator* GetLine() {
return GetFlag(LL_GOTLINEBOX) ? &mLineBox : nsnull;
}
/**
* 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>GetCurrentFrameXDistanceFromBlock() - lineContainer->GetUsedBorderAndPadding().left</code>
* Note the use of <code>.left</code> for both LTR and RTL line containers.
*/
nscoord GetCurrentFrameXDistanceFromBlock();
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 (vertical alignment, horizontal alignment,
// justification and relative positioning).
struct PerSpanData;
struct PerFrameData;
friend struct PerSpanData;
friend struct PerFrameData;
struct PerFrameData {
// 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;
nsRect mBounds;
nsOverflowAreas mOverflowAreas;
// From reflow-state
nsMargin mMargin;
nsMargin mBorderPadding;
nsMargin mOffsets;
// state for text justification
PRInt32 mJustificationNumSpaces;
PRInt32 mJustificationNumLetters;
// Other state we use
PRUint8 mVerticalAlign;
// 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
PRUint8 mFlags;
void SetFlag(PRUint32 aFlag, PRBool aValue)
{
NS_ASSERTION(aFlag<=PFD_LASTFLAG, "bad flag");
NS_ASSERTION(aFlag<=PR_UINT8_MAX, "bad flag");
NS_ASSERTION(aValue==PR_FALSE || aValue==PR_TRUE, "bad value");
if (aValue) { // set flag
mFlags |= aFlag;
}
else { // unset flag
mFlags &= ~aFlag;
}
}
PRBool GetFlag(PRUint32 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;
PRPackedBool mNoWrap;
PRUint8 mDirection;
PRPackedBool mChangedFrameDirection;
PRPackedBool mZeroEffectiveSpanBox;
PRPackedBool mContainsFloat;
PRPackedBool mHasNonemptyContent;
nscoord mLeftEdge;
nscoord mX;
nscoord mRightEdge;
nscoord mTopLeading, mBottomLeading;
nscoord mLogicalHeight;
nscoord mMinY, mMaxY;
void AppendFrame(PerFrameData* pfd) {
if (nsnull == mLastFrame) {
mFirstFrame = pfd;
}
else {
mLastFrame->mNext = pfd;
pfd->mPrev = mLastFrame;
}
mLastFrame = pfd;
}
};
PerSpanData* mSpanFreeList;
PerSpanData* mRootSpan;
PerSpanData* mCurrentSpan;
gfxBreakPriority mLastOptionalBreakPriority;
PRInt32 mLastOptionalBreakContentOffset;
PRInt32 mForceBreakContentOffset;
nscoord mMinLineHeight;
// 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.
PRInt32 mLineNumber;
PRInt32 mTextJustificationNumSpaces;
PRInt32 mTextJustificationNumLetters;
PRInt32 mTotalPlacedFrames;
nscoord mTopEdge;
nscoord mMaxTopBoxHeight;
nscoord mMaxBottomBoxHeight;
// Final computed line-height value after VerticalAlignFrames for
// the block has been called.
nscoord mFinalLineHeight;
// Amount of trimmable whitespace width for the trailing text frame, if any
nscoord mTrimmableWidth;
PRInt32 mSpanDepth;
#ifdef DEBUG
PRInt32 mSpansAllocated, mSpansFreed;
PRInt32 mFramesAllocated, mFramesFreed;
#endif
PLArenaPool mArena; // Per span and per frame data, 4 byte aligned
PRUint32 mFlags;
PRUint8 mTextAlign;
nsresult NewPerFrameData(PerFrameData** aResult);
nsresult NewPerSpanData(PerSpanData** aResult);
void FreeSpan(PerSpanData* psd);
PRBool InBlockContext() const {
return mSpanDepth == 0;
}
void PushFrame(nsIFrame* aFrame);
void ApplyStartMargin(PerFrameData* pfd,
nsHTMLReflowState& aReflowState);
PRBool CanPlaceFrame(PerFrameData* pfd,
PRUint8 aFrameDirection,
PRBool aNotSafeToBreak,
PRBool aFrameCanContinueTextRun,
PRBool aCanRollBackBeforeFrame,
nsHTMLReflowMetrics& aMetrics,
nsReflowStatus& aStatus,
PRBool* aOptionalBreakAfterFits);
void PlaceFrame(PerFrameData* pfd,
nsHTMLReflowMetrics& aMetrics);
void VerticalAlignFrames(PerSpanData* psd);
void PlaceTopBottomFrames(PerSpanData* psd,
nscoord aDistanceFromTop,
nscoord aLineHeight);
void RelativePositionFrames(PerSpanData* psd, nsOverflowAreas& aOverflowAreas);
PRBool TrimTrailingWhiteSpaceIn(PerSpanData* psd, nscoord* aDeltaWidth);
void ComputeJustificationWeights(PerSpanData* psd, PRInt32* numSpaces, PRInt32* numLetters);
struct FrameJustificationState {
PRInt32 mTotalNumSpaces;
PRInt32 mTotalNumLetters;
nscoord mTotalWidthForSpaces;
nscoord mTotalWidthForLetters;
PRInt32 mNumSpacesProcessed;
PRInt32 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, PRInt32 aIndent);
#endif
};
#endif /* nsLineLayout_h___ */
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