layout/generic/nsAbsoluteContainingBlock.h

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  37
  38 /*
  39  * code for managing absolutely positioned children of a rendering
  40  * object that is a containing block for them
  41  */
  42
  43 #ifndef nsAbsoluteContainingBlock_h___
  44 #define nsAbsoluteContainingBlock_h___
  45
  46 #include "nsFrameList.h"
  47 #include "nsHTMLReflowState.h"
  48 #include "nsGkAtoms.h"
  49 #include "nsContainerFrame.h"
  50
  51 class nsIAtom;
  52 class nsIFrame;
  53 class nsPresContext;
  54
  55 /**
  56  * This class contains the logic for being an absolute containing block.  This
  57  * class is used within viewport frames (for frames representing content with
  58  * fixed position) and blocks (for frames representing absolutely positioned
  59  * content), since each set of frames is absolutely positioned with respect to
  60  * its parent.
  61  *
  62  * There is no principal child list, just a named child list which contains
  63  * the absolutely positioned frames.
  64  *
  65  * All functions include as the first argument the frame that is delegating
  66  * the request.
  67  *
  68  * @see nsGkAtoms::absoluteList and nsGkAtoms::fixedList
  69  */
  70 class nsAbsoluteContainingBlock
  71 {
  72 public:
  73   nsAbsoluteContainingBlock(nsIAtom* aChildListName)
  74 #ifdef DEBUG
  75     : mChildListName(aChildListName)
  76 #endif
  77   {
  78     NS_ASSERTION(mChildListName == nsGkAtoms::absoluteList ||
  79                  mChildListName == nsGkAtoms::fixedList,
  80                  "should either represent position:fixed or absolute content");
  81   }
  82
  83 #ifdef DEBUG
  84   nsIAtom* GetChildListName() const { return mChildListName; }
  85 #endif
  86
  87   const nsFrameList& GetChildList() const { return mAbsoluteFrames; }
  88
  89   nsresult SetInitialChildList(nsIFrame*       aDelegatingFrame,
  90                                nsIAtom*        aListName,
  91                                nsFrameList&    aChildList);
  92   nsresult AppendFrames(nsIFrame*      aDelegatingFrame,
  93                         nsIAtom*       aListName,
  94                         nsFrameList&   aFrameList);
  95   nsresult InsertFrames(nsIFrame*      aDelegatingFrame,
  96                         nsIAtom*       aListName,
  97                         nsIFrame*      aPrevFrame,
  98                         nsFrameList&   aFrameList);
  99   void RemoveFrame(nsIFrame*      aDelegatingFrame,
 100                    nsIAtom*       aListName,
 101                    nsIFrame*      aOldFrame);
 102
 103   // Called by the delegating frame after it has done its reflow first. This
 104   // function will reflow any absolutely positioned child frames that need to
 105   // be reflowed, e.g., because the absolutely positioned child frame has
 106   // 'auto' for an offset, or a percentage based width or height.
 107   // If aChildBounds is set, it returns (in the local coordinate space) the
 108   // bounding rect of the absolutely positioned child elements taking into
 109   // account their overflow area (if it is visible).
 110   // @param aForceReflow if this is false, reflow for some absolutely
 111   //        positioned frames may be skipped based on whether they use
 112   //        placeholders for positioning and on whether the containing block
 113   //        width or height changed.
 114   nsresult Reflow(nsContainerFrame*        aDelegatingFrame,
 115                   nsPresContext*           aPresContext,
 116                   const nsHTMLReflowState& aReflowState,
 117                   nsReflowStatus&          aReflowStatus,
 118                   nscoord                  aContainingBlockWidth,
 119                   nscoord                  aContainingBlockHeight,
 120                   PRBool                   aConstrainHeight,
 121                   PRBool                   aCBWidthChanged,
 122                   PRBool                   aCBHeightChanged,
 123                   nsRect*                  aChildBounds = nsnull);
 124
 125
 126   void DestroyFrames(nsIFrame* aDelegatingFrame,
 127                      nsIFrame* aDestructRoot);
 128
 129   PRBool  HasAbsoluteFrames() {return mAbsoluteFrames.NotEmpty();}
 130
 131   // Mark our size-dependent absolute frames with NS_FRAME_HAS_DIRTY_CHILDREN
 132   // so that we'll make sure to reflow them.
 133   void MarkSizeDependentFramesDirty();
 134
 135   // Mark all our absolute frames with NS_FRAME_IS_DIRTY
 136   void MarkAllFramesDirty();
 137
 138 protected:
 139   // Returns PR_TRUE if the position of f depends on the position of
 140   // its placeholder or if the position or size of f depends on a
 141   // containing block dimension that changed.
 142   PRBool FrameDependsOnContainer(nsIFrame* f, PRBool aCBWidthChanged,
 143                                  PRBool aCBHeightChanged);
 144
 145   nsresult ReflowAbsoluteFrame(nsIFrame*                aDelegatingFrame,
 146                                nsPresContext*          aPresContext,
 147                                const nsHTMLReflowState& aReflowState,
 148                                nscoord                  aContainingBlockWidth,
 149                                nscoord                  aContainingBlockHeight,
 150                                PRBool                   aConstrainHeight,
 151                                nsIFrame*                aKidFrame,
 152                                nsReflowStatus&          aStatus,
 153                                nsRect*                  aChildBounds);
 154
 155   // Mark our absolute frames dirty.  If aMarkAllDirty is true, all will be
 156   // marked with NS_FRAME_IS_DIRTY.  Otherwise, the size-dependant ones will be
 157   // marked with NS_FRAME_HAS_DIRTY_CHILDREN.
 158   void DoMarkFramesDirty(PRBool aMarkAllDirty);
 159
 160 protected:
 161   nsFrameList mAbsoluteFrames;  // additional named child list
 162
 163 #ifdef DEBUG
 164   nsIAtom* const mChildListName; // nsGkAtoms::fixedList or nsGkAtoms::absoluteList
 165
 166   // helper routine for debug printout
 167   void PrettyUC(nscoord aSize,
 168                 char*   aBuf);
 169 #endif
 170 };
 171
 172 #endif /* nsnsAbsoluteContainingBlock_h___ */
 173