gecko-dev/layout/generic/nsBlockReflowState.h

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 * The Original Code is Mozilla Communicator client code.
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 * The Initial Developer of the Original Code is
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 * Contributor(s):
 *   Steve Clark <buster@netscape.com>
 *   Robert O'Callahan <roc+moz@cs.cmu.edu>
 *   L. David Baron <dbaron@dbaron.org>
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/* state used in reflow of block frames */

#ifndef nsBlockReflowState_h__
#define nsBlockReflowState_h__

#include "nsBlockBandData.h"
#include "nsLineBox.h"
#include "nsFrameList.h"

class nsBlockFrame;

  // block reflow state flags
#define BRS_UNCONSTRAINEDHEIGHT   0x00000001
#define BRS_ISTOPMARGINROOT       0x00000002  // Is this frame a root for top/bottom margin collapsing?
#define BRS_ISBOTTOMMARGINROOT    0x00000004
#define BRS_APPLYTOPMARGIN        0x00000008  // See ShouldApplyTopMargin
#define BRS_ISFIRSTINFLOW         0x00000010
// Set when mLineAdjacentToTop is valid
#define BRS_HAVELINEADJACENTTOTOP 0x00000020
// Set when the block has the equivalent of NS_BLOCK_SPACE_MGR
#define BRS_SPACE_MGR             0x00000040
#define BRS_LASTFLAG              BRS_SPACE_MGR

class nsBlockReflowState {
public:
  nsBlockReflowState(const nsHTMLReflowState& aReflowState,
                     nsPresContext* aPresContext,
                     nsBlockFrame* aFrame,
                     const nsHTMLReflowMetrics& aMetrics,
                     PRBool aTopMarginRoot, PRBool aBottomMarginRoot,
                     PRBool aBlockNeedsSpaceManager);

  ~nsBlockReflowState();

  // Set up a property on the block that points to our temporary mOverflowPlaceholders
  // list, if that list is or could become non-empty during this reflow. Must be
  // called after the block has done DrainOverflowLines because DrainOverflowLines
  // can setup mOverflowPlaceholders even if the block is in unconstrained height
  // reflow (it may have previously been reflowed with constrained height).
  void SetupOverflowPlaceholdersProperty();

  /**
   * Get the available reflow space for the current y coordinate. The
   * available space is relative to our coordinate system (0,0) is our
   * upper left corner.
   */
  void GetAvailableSpace() { GetAvailableSpace(mY, PR_FALSE); }
  void GetAvailableSpace(nscoord aY, PRBool aRelaxHeightConstraint);

  /*
   * The following functions all return PR_TRUE if they were able to
   * place the float, PR_FALSE if the float did not fit in available
   * space.
   */
  PRBool InitFloat(nsLineLayout&       aLineLayout,
                   nsPlaceholderFrame* aPlaceholderFrame,
                   nsReflowStatus&     aReflowStatus);
  PRBool AddFloat(nsLineLayout&       aLineLayout,
                  nsPlaceholderFrame* aPlaceholderFrame,
                  PRBool              aInitialReflow,
                  nsReflowStatus&     aReflowStatus);
  PRBool CanPlaceFloat(const nsSize& aFloatSize, PRUint8 aFloats, PRBool aForceFit);
  PRBool FlowAndPlaceFloat(nsFloatCache*   aFloatCache,
                           PRBool*         aIsLeftFloat,
                           nsReflowStatus& aReflowStatus,
                           PRBool          aForceFit);
  PRBool PlaceBelowCurrentLineFloats(nsFloatCacheFreeList& aFloats, PRBool aForceFit);

  // Returns the first coordinate >= aY that clears the
  // indicated floats.
  nscoord ClearFloats(nscoord aY, PRUint8 aBreakType);

  PRBool IsAdjacentWithTop() const {
    return mY ==
      ((mFlags & BRS_ISFIRSTINFLOW) ? mReflowState.mComputedBorderPadding.top : 0);
  }

  /**
   * Adjusts the border/padding to return 0 for the top if
   * we are no the first in flow.
   */
  nsMargin BorderPadding() const {
    nsMargin result = mReflowState.mComputedBorderPadding;
    if (!(mFlags & BRS_ISFIRSTINFLOW)) {
      result.top = 0;
    }
    return result;
  }

  // XXX maybe we should do the same adjustment for continuations here
  const nsMargin& Margin() const {
    return mReflowState.mComputedMargin;
  }

  // Reconstruct the previous bottom margin that goes above |aLine|.
  void ReconstructMarginAbove(nsLineList::iterator aLine);

  void ComputeBlockAvailSpace(nsIFrame* aFrame,
                              const nsStyleDisplay* aDisplay,
                              nsRect& aResult);

protected:
  void RecoverFloats(nsLineList::iterator aLine, nscoord aDeltaY);

public:
  void RecoverStateFrom(nsLineList::iterator aLine, nscoord aDeltaY);

  void AdvanceToNextLine() {
    mLineNumber++;
  }

  PRBool IsImpactedByFloat() const;

  nsLineBox* NewLineBox(nsIFrame* aFrame, PRInt32 aCount, PRBool aIsBlock);

  void FreeLineBox(nsLineBox* aLine);

  //----------------------------------------

  // This state is the "global" state computed once for the reflow of
  // the block.

  // The block frame that is using this object
  nsBlockFrame* mBlock;

  nsPresContext* mPresContext;

  const nsHTMLReflowState& mReflowState;

  nsSpaceManager* mSpaceManager;

  // The coordinates within the spacemanager where the block is being
  // placed <b>after</b> taking into account the blocks border and
  // padding. This, therefore, represents the inner "content area" (in
  // spacemanager coordinates) where child frames will be placed,
  // including child blocks and floats.
  nscoord mSpaceManagerX, mSpaceManagerY;

  // XXX get rid of this
  nsReflowStatus mReflowStatus;

  nscoord mBottomEdge;

  // The content area to reflow child frames within. The x/y
  // coordinates are known to be mBorderPadding.left and
  // mBorderPadding.top. The width/height may be NS_UNCONSTRAINEDSIZE
  // if the container reflowing this frame has given the frame an
  // unconstrained area.
  nsSize mContentArea;

  // Placeholders for continuation out-of-flow frames that need to
  // move to our next in flow are placed here during reflow. At the end of reflow
  // they move to the end of the overflow lines.
  // Their out-of-flows are not in any child list during reflow, but are added
  // to the overflow-out-of-flow list when the placeholders are appended to
  // the overflow lines.
  nsFrameList mOverflowPlaceholders;

  //----------------------------------------

  // This state is "running" state updated by the reflow of each line
  // in the block. This same state is "recovered" when a line is not
  // dirty and is passed over during incremental reflow.

  // The current line being reflowed
  // If it is mBlock->end_lines(), then it is invalid.
  nsLineList::iterator mCurrentLine;

  // When BRS_HAVELINEADJACENTTOTOP is set, this refers to a line
  // which we know is adjacent to the top of the block (in other words,
  // all lines before it are empty and do not have clearance. This line is
  // always before the current line.
  nsLineList::iterator mLineAdjacentToTop;

  // The current Y coordinate in the block
  nscoord mY;

  // The available space within the current band.
  nsRect mAvailSpaceRect;

  // The combined area of all floats placed so far
  nsRect mFloatCombinedArea;

  nsFloatCacheFreeList mFloatCacheFreeList;

  // Previous child. This is used when pulling up a frame to update
  // the sibling list.
  nsIFrame* mPrevChild;

  // The previous child frames collapsed bottom margin value.
  nsCollapsingMargin mPrevBottomMargin;

  // The current next-in-flow for the block. When lines are pulled
  // from a next-in-flow, this is used to know which next-in-flow to
  // pull from. When a next-in-flow is emptied of lines, we advance
  // this to the next next-in-flow.
  nsBlockFrame* mNextInFlow;

  // The current band data for the current Y coordinate
  nsBlockBandData mBand;

  //----------------------------------------

  // Temporary line-reflow state. This state is used during the reflow
  // of a given line, but doesn't have meaning before or after.

  // The list of floats that are "current-line" floats. These are
  // added to the line after the line has been reflowed, to keep the
  // list fiddling from being N^2.
  nsFloatCacheFreeList mCurrentLineFloats;

  // The list of floats which are "below current-line"
  // floats. These are reflowed/placed after the line is reflowed
  // and placed. Again, this is done to keep the list fiddling from
  // being N^2.
  nsFloatCacheFreeList mBelowCurrentLineFloats;

  nscoord mMinLineHeight;

  PRInt32 mLineNumber;

  PRInt16 mFlags;
 
  PRUint8 mFloatBreakType;

  void SetFlag(PRUint32 aFlag, PRBool aValue)
  {
    NS_ASSERTION(aFlag<=BRS_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<=BRS_LASTFLAG, "bad flag");
    PRBool result = (mFlags & aFlag);
    if (result) return PR_TRUE;
    return PR_FALSE;
  }
};

#endif // nsBlockReflowState_h__