/* -*- 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): * * 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 ***** */ /* * rendering object for CSS display:block, inline-block, and list-item * boxes, also used for various anonymous boxes */ #ifndef nsBlockFrame_h___ #define nsBlockFrame_h___ #include "nsHTMLContainerFrame.h" #include "nsHTMLParts.h" #include "nsAbsoluteContainingBlock.h" #include "nsLineBox.h" #include "nsCSSPseudoElements.h" #include "nsStyleSet.h" enum LineReflowStatus { // The line was completely reflowed and fit in available width, and we should // try to pull up content from the next line if possible. LINE_REFLOW_OK, // The line was completely reflowed and fit in available width, but we should // not try to pull up content from the next line. LINE_REFLOW_STOP, // We need to reflow the line again at its current vertical position. The // new reflow should not try to pull up any frames from the next line. LINE_REFLOW_REDO_NO_PULL, // We need to reflow the line again at a lower vertical postion where there // may be more horizontal space due to different float configuration. LINE_REFLOW_REDO_NEXT_BAND, // The line did not fit in the available vertical space. Try pushing it to // the next page or column if it's not the first line on the current page/column. LINE_REFLOW_TRUNCATED }; class nsBlockReflowState; class nsBlockInFlowLineIterator; class nsBulletFrame; class nsLineBox; class nsFirstLineFrame; class nsILineIterator; class nsIntervalSet; /** * Child list name indices * @see #GetAdditionalChildListName() */ #define NS_BLOCK_LIST_COUNT (NS_CONTAINER_LIST_COUNT_INCL_OC + 4) /** * Some invariants: * -- The overflow out-of-flows list contains the out-of- * flow frames whose placeholders are in the overflow list. * -- A given piece of content has at most one placeholder * frame in a block's normal child list. * -- A given piece of content can have an unlimited number * of placeholder frames in the overflow-lines list. * -- A line containing a continuation placeholder contains * only continuation placeholders. * -- While a block is being reflowed, its overflowPlaceholdersList * frame property points to an nsFrameList in its * nsBlockReflowState. This list contains placeholders for * floats whose prev-in-flow is in the block's regular line * list. The list is always empty/non-existent after the * block has been reflowed. * -- In all these frame lists, if there are two frames for * the same content appearing in the list, then the frames * appear with the prev-in-flow before the next-in-flow. * -- While reflowing a block, its overflow line list * will usually be empty but in some cases will have lines * (while we reflow the block at its shrink-wrap width). * In this case any new overflowing content must be * prepended to the overflow lines. */ // see nsHTMLParts.h for the public block state bits /** * Something in the block has changed that requires Bidi resolution to be * performed on the block. This flag must be either set on all blocks in a * continuation chain or none of them. */ #define NS_BLOCK_NEEDS_BIDI_RESOLUTION 0x00100000 #define NS_BLOCK_HAS_LINE_CURSOR 0x01000000 #define NS_BLOCK_HAS_OVERFLOW_LINES 0x02000000 #define NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS 0x04000000 #define NS_BLOCK_HAS_OVERFLOW_PLACEHOLDERS 0x08000000 // Set on any block that has descendant frames in the normal // flow with 'clear' set to something other than 'none' // (including
frames) #define NS_BLOCK_HAS_CLEAR_CHILDREN 0x10000000 #define nsBlockFrameSuper nsHTMLContainerFrame #define NS_BLOCK_FRAME_CID \ { 0xa6cf90df, 0x15b3, 0x11d2,{0x93, 0x2e, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32}} extern const nsIID kBlockFrameCID; /* * Base class for block and inline frames. * The block frame has an additional named child list: * - "Absolute-list" which contains the absolutely positioned frames * * @see nsGkAtoms::absoluteList */ class nsBlockFrame : public nsBlockFrameSuper { public: typedef nsLineList::iterator line_iterator; typedef nsLineList::const_iterator const_line_iterator; typedef nsLineList::reverse_iterator reverse_line_iterator; typedef nsLineList::const_reverse_iterator const_reverse_line_iterator; line_iterator begin_lines() { return mLines.begin(); } line_iterator end_lines() { return mLines.end(); } const_line_iterator begin_lines() const { return mLines.begin(); } const_line_iterator end_lines() const { return mLines.end(); } reverse_line_iterator rbegin_lines() { return mLines.rbegin(); } reverse_line_iterator rend_lines() { return mLines.rend(); } const_reverse_line_iterator rbegin_lines() const { return mLines.rbegin(); } const_reverse_line_iterator rend_lines() const { return mLines.rend(); } friend nsIFrame* NS_NewBlockFrame(nsIPresShell* aPresShell, nsStyleContext* aContext, PRUint32 aFlags); // nsISupports NS_IMETHOD QueryInterface(const nsIID& aIID, void** aInstancePtr); // nsIFrame NS_IMETHOD Init(nsIContent* aContent, nsIFrame* aParent, nsIFrame* aPrevInFlow); NS_IMETHOD SetInitialChildList(nsIAtom* aListName, nsIFrame* aChildList); NS_IMETHOD AppendFrames(nsIAtom* aListName, nsIFrame* aFrameList); NS_IMETHOD InsertFrames(nsIAtom* aListName, nsIFrame* aPrevFrame, nsIFrame* aFrameList); NS_IMETHOD RemoveFrame(nsIAtom* aListName, nsIFrame* aOldFrame); virtual nsIFrame* GetFirstChild(nsIAtom* aListName) const; virtual nscoord GetBaseline() const; virtual nsIAtom* GetAdditionalChildListName(PRInt32 aIndex) const; virtual void Destroy(); virtual nsSplittableType GetSplittableType() const; virtual PRBool IsContainingBlock() const; virtual PRBool IsFloatContainingBlock() const; NS_IMETHOD BuildDisplayList(nsDisplayListBuilder* aBuilder, const nsRect& aDirtyRect, const nsDisplayListSet& aLists); virtual void InvalidateInternal(const nsRect& aDamageRect, nscoord aX, nscoord aY, nsIFrame* aForChild, PRBool aImmediate); virtual nsIAtom* GetType() const; virtual PRBool IsFrameOfType(PRUint32 aFlags) const { return nsContainerFrame::IsFrameOfType(aFlags & ~(nsIFrame::eCanContainOverflowContainers | nsIFrame::eBlockFrame)); } #ifdef DEBUG NS_IMETHOD List(FILE* out, PRInt32 aIndent) const; NS_IMETHOD_(nsFrameState) GetDebugStateBits() const; NS_IMETHOD GetFrameName(nsAString& aResult) const; NS_IMETHOD VerifyTree() const; #endif #ifdef ACCESSIBILITY NS_IMETHOD GetAccessible(nsIAccessible** aAccessible); #endif // line cursor methods to speed up searching for the line(s) // containing a point. The basic idea is that we set the cursor // property if the lines' combinedArea.ys and combinedArea.yMosts // are non-decreasing (considering only non-empty combinedAreas; // empty combinedAreas never participate in event handling or // painting), and the block has sufficient number of lines. The // cursor property points to a "recently used" line. If we get a // series of requests that work on lines // "near" the cursor, then we can find those nearby lines quickly by // starting our search at the cursor. // Clear out line cursor because we're disturbing the lines (i.e., Reflow) void ClearLineCursor(); // Get the first line that might contain y-coord 'y', or nsnull if you must search // all lines. If nonnull is returned then we guarantee that the lines' // combinedArea.ys and combinedArea.yMosts are non-decreasing. // The actual line returned might not contain 'y', but if not, it is guaranteed // to be before any line which does contain 'y'. nsLineBox* GetFirstLineContaining(nscoord y); // Set the line cursor to our first line. Only call this if you // guarantee that the lines' combinedArea.ys and combinedArea.yMosts // are non-decreasing. void SetupLineCursor(); virtual void ChildIsDirty(nsIFrame* aChild); virtual PRBool IsVisibleInSelection(nsISelection* aSelection); virtual PRBool IsEmpty(); virtual PRBool CachedIsEmpty(); virtual PRBool IsSelfEmpty(); virtual void MarkIntrinsicWidthsDirty(); virtual nscoord GetMinWidth(nsIRenderingContext *aRenderingContext); virtual nscoord GetPrefWidth(nsIRenderingContext *aRenderingContext); virtual nsRect ComputeTightBounds(gfxContext* aContext) const; NS_IMETHOD Reflow(nsPresContext* aPresContext, nsHTMLReflowMetrics& aDesiredSize, const nsHTMLReflowState& aReflowState, nsReflowStatus& aStatus); NS_IMETHOD AttributeChanged(PRInt32 aNameSpaceID, nsIAtom* aAttribute, PRInt32 aModType); virtual nsresult StealFrame(nsPresContext* aPresContext, nsIFrame* aChild, PRBool aForceNormal); virtual void DeleteNextInFlowChild(nsPresContext* aPresContext, nsIFrame* aNextInFlow); /** * Determines whether the collapsed margin carried out of the last * line includes the margin-top of a line with clearance (in which * case we must avoid collapsing that margin with our bottom margin) */ PRBool CheckForCollapsedBottomMarginFromClearanceLine(); /** return the topmost block child based on y-index. * almost always the first or second line, if there is one. * accounts for lines that hold only compressed white space, etc. */ nsIFrame* GetTopBlockChild(nsPresContext *aPresContext); static nsresult GetCurrentLine(nsBlockReflowState *aState, nsLineBox **aOutCurrentLine); // Create a contination for aPlaceholder and its out of flow frame and // add it to the list of overflow floats nsresult SplitPlaceholder(nsBlockReflowState& aState, nsIFrame* aPlaceholder); PRBool HandleOverflowPlaceholdersForPulledFrame( nsBlockReflowState& aState, nsIFrame* aFrame); PRBool HandleOverflowPlaceholdersOnPulledLine( nsBlockReflowState& aState, nsLineBox* aLine); static PRBool BlockIsMarginRoot(nsIFrame* aBlock); static PRBool BlockNeedsSpaceManager(nsIFrame* aBlock); /** * Returns whether aFrame is a block frame that will wrap its contents * around floats intruding on it from the outside. (aFrame need not * be a block frame, but if it's not, the result will be false.) */ static PRBool BlockCanIntersectFloats(nsIFrame* aFrame); /** * Returns the width that needs to be cleared past floats for blocks * that cannot intersect floats. */ static nscoord WidthToClearPastFloats(nsBlockReflowState& aState, nsIFrame* aFrame); /** * Walks up the frame tree, starting with aCandidate, and returns the first * block frame that it encounters. */ static nsBlockFrame* GetNearestAncestorBlock(nsIFrame* aCandidate); protected: nsBlockFrame(nsStyleContext* aContext) : nsHTMLContainerFrame(aContext) , mMinWidth(NS_INTRINSIC_WIDTH_UNKNOWN) , mPrefWidth(NS_INTRINSIC_WIDTH_UNKNOWN) , mAbsoluteContainer(nsGkAtoms::absoluteList) { #ifdef DEBUG InitDebugFlags(); #endif } virtual ~nsBlockFrame(); #ifdef DEBUG already_AddRefed GetFirstLetterStyle(nsPresContext* aPresContext) { return aPresContext->StyleSet()-> ProbePseudoStyleFor(mContent, nsCSSPseudoElements::firstLetter, mStyleContext); } #endif /* * Overides member function of nsHTMLContainerFrame. Needed to handle the * lines in a nsBlockFrame properly. */ virtual void PaintTextDecorationLine(nsIRenderingContext& aRenderingContext, const nsPoint& aPt, nsLineBox* aLine, nscolor aColor, gfxFloat aOffset, gfxFloat aAscent, gfxFloat aSize, const PRUint8 aDecoration); void TryAllLines(nsLineList::iterator* aIterator, nsLineList::iterator* aStartIterator, nsLineList::iterator* aEndIterator, PRBool* aInOverflowLines); void SetFlags(PRUint32 aFlags) { mState &= ~NS_BLOCK_FLAGS_MASK; mState |= aFlags; } PRBool HaveOutsideBullet() const { #if defined(DEBUG) && !defined(DEBUG_rods) if(mState & NS_BLOCK_FRAME_HAS_OUTSIDE_BULLET) { NS_ASSERTION(mBullet,"NS_BLOCK_FRAME_HAS_OUTSIDE_BULLET flag set and no mBullet"); } #endif return 0 != (mState & NS_BLOCK_FRAME_HAS_OUTSIDE_BULLET); } /** move the frames contained by aLine by aDY * if aLine is a block, its child floats are added to the state manager */ void SlideLine(nsBlockReflowState& aState, nsLineBox* aLine, nscoord aDY); virtual PRIntn GetSkipSides() const; virtual void ComputeFinalSize(const nsHTMLReflowState& aReflowState, nsBlockReflowState& aState, nsHTMLReflowMetrics& aMetrics); void ComputeCombinedArea(const nsHTMLReflowState& aReflowState, nsHTMLReflowMetrics& aMetrics); /** add the frames in aFrameList to this block after aPrevSibling * this block thinks in terms of lines, but the frame construction code * knows nothing about lines at all. So we need to find the line that * contains aPrevSibling and add aFrameList after aPrevSibling on that line. * new lines are created as necessary to handle block data in aFrameList. */ virtual nsresult AddFrames(nsIFrame* aFrameList, nsIFrame* aPrevSibling); #ifdef IBMBIDI /** * Perform Bidi resolution on this frame */ nsresult ResolveBidi(); /** * Test whether the frame is a form control in a visual Bidi page. * This is necessary for backwards-compatibility, because most visual * pages use logical order for form controls so that they will * display correctly on native widgets in OSs with Bidi support * @param aPresContext the pres context * @return whether the frame is a BIDI form control */ PRBool IsVisualFormControl(nsPresContext* aPresContext); #endif public: /** does all the real work for removing aDeletedFrame from this * finds the line containing aFrame. * handled continued frames * marks lines dirty as needed * @param aDestroyFrames if false then we don't actually destroy the * frame or its next in flows, we just remove them. This does NOT work * on out of flow frames so always use PR_TRUE for out of flows. * @param aRemoveOnlyFluidContinuations if true, only in-flows are removed; * if false, all continuations are removed. */ nsresult DoRemoveFrame(nsIFrame* aDeletedFrame, PRBool aDestroyFrames = PR_TRUE, PRBool aRemoveOnlyFluidContinuations = PR_TRUE); void ReparentFloats(nsIFrame* aFirstFrame, nsBlockFrame* aOldParent, PRBool aFromOverflow, PRBool aReparentSiblings); protected: /** grab overflow lines from this block's prevInFlow, and make them * part of this block's mLines list. * @return PR_TRUE if any lines were drained. */ PRBool DrainOverflowLines(nsBlockReflowState& aState); /** * Remove a float from our float list and also the float cache * for the line its placeholder is on. */ line_iterator RemoveFloat(nsIFrame* aFloat); void CollectFloats(nsIFrame* aFrame, nsFrameList& aList, nsIFrame** aTail, PRBool aFromOverflow, PRBool aCollectFromSiblings); // Remove a float, abs, rel positioned frame from the appropriate block's list static void DoRemoveOutOfFlowFrame(nsIFrame* aFrame); /** set up the conditions necessary for an resize reflow * the primary task is to mark the minimumly sufficient lines dirty. */ nsresult PrepareResizeReflow(nsBlockReflowState& aState); /** reflow all lines that have been marked dirty */ nsresult ReflowDirtyLines(nsBlockReflowState& aState); //---------------------------------------- // Methods for line reflow /** * Reflow a line. * @param aState the current reflow state * @param aLine the line to reflow. can contain a single block frame * or contain 1 or more inline frames. * @param aKeepReflowGoing [OUT] indicates whether the caller should continue to reflow more lines */ nsresult ReflowLine(nsBlockReflowState& aState, line_iterator aLine, PRBool* aKeepReflowGoing); // Return PR_TRUE if aLine gets pushed. void PlaceLine(nsBlockReflowState& aState, nsLineLayout& aLineLayout, line_iterator aLine, PRBool* aKeepReflowGoing); /** * Mark |aLine| dirty, and, if necessary because of possible * pull-up, mark the previous line dirty as well. Also invalidates textruns * on those lines because the text in the lines might have changed due to * addition/removal of frames. */ nsresult MarkLineDirty(line_iterator aLine); // XXX where to go PRBool ShouldJustifyLine(nsBlockReflowState& aState, line_iterator aLine); void DeleteLine(nsBlockReflowState& aState, nsLineList::iterator aLine, nsLineList::iterator aLineEnd); //---------------------------------------- // Methods for individual frame reflow PRBool ShouldApplyTopMargin(nsBlockReflowState& aState, nsLineBox* aLine); nsresult ReflowBlockFrame(nsBlockReflowState& aState, line_iterator aLine, PRBool* aKeepGoing); nsresult ReflowInlineFrames(nsBlockReflowState& aState, line_iterator aLine, PRBool* aKeepLineGoing); nsresult DoReflowInlineFrames(nsBlockReflowState& aState, nsLineLayout& aLineLayout, line_iterator aLine, PRBool* aKeepReflowGoing, LineReflowStatus* aLineReflowStatus, PRBool aAllowPullUp); nsresult ReflowInlineFrame(nsBlockReflowState& aState, nsLineLayout& aLineLayout, line_iterator aLine, nsIFrame* aFrame, LineReflowStatus* aLineReflowStatus); // An incomplete aReflowStatus indicates the float should be split // but only if the available height is constrained. nsresult ReflowFloat(nsBlockReflowState& aState, nsPlaceholderFrame* aPlaceholder, nsMargin& aFloatMargin, nsReflowStatus& aReflowStatus); //---------------------------------------- // Methods for pushing/pulling lines/frames virtual nsresult CreateContinuationFor(nsBlockReflowState& aState, nsLineBox* aLine, nsIFrame* aFrame, PRBool& aMadeNewFrame); // Push aLine which contains a positioned element that was truncated. Clean up any // placeholders on the same line that were continued. Set aKeepReflowGoing to false. void PushTruncatedPlaceholderLine(nsBlockReflowState& aState, line_iterator aLine, PRBool& aKeepReflowGoing); nsresult SplitLine(nsBlockReflowState& aState, nsLineLayout& aLineLayout, line_iterator aLine, nsIFrame* aFrame, LineReflowStatus* aLineReflowStatus); nsresult PullFrame(nsBlockReflowState& aState, line_iterator aLine, nsIFrame*& aFrameResult); PRBool PullFrameFrom(nsBlockReflowState& aState, nsLineBox* aLine, nsBlockFrame* aFromContainer, PRBool aFromOverflowLine, nsLineList::iterator aFromLine, nsIFrame*& aFrameResult); void PushLines(nsBlockReflowState& aState, nsLineList::iterator aLineBefore); void PropagateFloatDamage(nsBlockReflowState& aState, nsLineBox* aLine, nscoord aDeltaY); void CheckFloats(nsBlockReflowState& aState); //---------------------------------------- // List handling kludge // If this returns PR_TRUE, the block it's called on should get the // NS_FRAME_HAS_DIRTY_CHILDREN bit set on it by the caller; either directly // if it's already in reflow, or via calling FrameNeedsReflow() to schedule a // reflow. PRBool RenumberLists(nsPresContext* aPresContext); static PRBool RenumberListsInBlock(nsPresContext* aPresContext, nsBlockFrame* aBlockFrame, PRInt32* aOrdinal, PRInt32 aDepth); static PRBool RenumberListsFor(nsPresContext* aPresContext, nsIFrame* aKid, PRInt32* aOrdinal, PRInt32 aDepth); static PRBool FrameStartsCounterScope(nsIFrame* aFrame); void ReflowBullet(nsBlockReflowState& aState, nsHTMLReflowMetrics& aMetrics, nscoord aLineTop); //---------------------------------------- public: nsLineList* GetOverflowLines() const; protected: nsLineList* RemoveOverflowLines(); nsresult SetOverflowLines(nsLineList* aOverflowLines); nsFrameList* GetOverflowPlaceholders() const; /** * This class is useful for efficiently modifying the out of flow * overflow list. It gives the client direct writable access to * the frame list temporarily but ensures that property is only * written back if absolutely necessary. */ struct nsAutoOOFFrameList { nsFrameList mList; nsAutoOOFFrameList(nsBlockFrame* aBlock) : mList(aBlock->GetOverflowOutOfFlows().FirstChild()), aOldHead(mList.FirstChild()), mBlock(aBlock) {} ~nsAutoOOFFrameList() { if (mList.FirstChild() != aOldHead) { mBlock->SetOverflowOutOfFlows(mList); } } protected: nsIFrame* aOldHead; nsBlockFrame* mBlock; }; friend struct nsAutoOOFFrameList; nsFrameList GetOverflowOutOfFlows() const; void SetOverflowOutOfFlows(const nsFrameList& aList); nsIFrame* LastChild(); #ifdef NS_DEBUG void VerifyLines(PRBool aFinalCheckOK); void VerifyOverflowSituation(); PRInt32 GetDepth() const; #endif nscoord mMinWidth, mPrefWidth; nsLineList mLines; // List of all floats in this block nsFrameList mFloats; // XXX_fix_me: subclass one more time! // For list-item frames, this is the bullet frame. nsBulletFrame* mBullet; friend class nsBlockReflowState; friend class nsBlockInFlowLineIterator; private: nsAbsoluteContainingBlock mAbsoluteContainer; #ifdef DEBUG public: static PRBool gLamePaintMetrics; static PRBool gLameReflowMetrics; static PRBool gNoisy; static PRBool gNoisyDamageRepair; static PRBool gNoisyIntrinsic; static PRBool gNoisyReflow; static PRBool gReallyNoisyReflow; static PRBool gNoisySpaceManager; static PRBool gVerifyLines; static PRBool gDisableResizeOpt; static PRInt32 gNoiseIndent; static const char* kReflowCommandType[]; protected: static void InitDebugFlags(); #endif }; #ifdef DEBUG class AutoNoisyIndenter { public: AutoNoisyIndenter(PRBool aDoIndent) : mIndented(aDoIndent) { if (mIndented) { nsBlockFrame::gNoiseIndent++; } } ~AutoNoisyIndenter() { if (mIndented) { nsBlockFrame::gNoiseIndent--; } } private: PRBool mIndented; }; #endif /** * Iterates over all lines in the prev-in-flows/next-in-flows of this block. */ class nsBlockInFlowLineIterator { public: typedef nsBlockFrame::line_iterator line_iterator; nsBlockInFlowLineIterator(nsBlockFrame* aFrame, line_iterator aLine, PRBool aInOverflow); /** * Set up the iterator to point to the first line found starting from * aFrame. Sets aFoundValidLine to false if there is no such line. */ nsBlockInFlowLineIterator(nsBlockFrame* aFrame, PRBool* aFoundValidLine); /** * Set up the iterator to point to the line that contains aFindFrame (either * directly or indirectly). If aFrame is out of flow, or contained in an * out-of-flow, finds the line containing the out-of-flow's placeholder. If * the frame is not found, sets aFoundValidLine to false. */ nsBlockInFlowLineIterator(nsBlockFrame* aFrame, nsIFrame* aFindFrame, PRBool* aFoundValidLine); line_iterator GetLine() { return mLine; } PRBool IsLastLineInList(); nsBlockFrame* GetContainer() { return mFrame; } PRBool GetInOverflow() { return mInOverflowLines != nsnull; } /** * Returns false if there are no more lines. After this has returned false, * don't call any methods on this object again. */ PRBool Next(); /** * Returns false if there are no more lines. After this has returned false, * don't call any methods on this object again. */ PRBool Prev(); private: nsBlockFrame* mFrame; line_iterator mLine; nsLineList* mInOverflowLines; /** * Moves iterator to next valid line reachable from the current block. * Returns false if there are no valid lines. */ PRBool FindValidLine(); }; #endif /* nsBlockFrame_h___ */