Bug 10209 - Part 1: Add an API for absolute container support for all frame types; r=roc

layout/base/nsCSSFrameConstructor.cpp

@@ -1022,6 +1022,8 @@ nsFrameConstructorState::PushAbsoluteContainingBlock(nsIFrame* aNewAbsoluteConta
    */
   mFixedPosIsAbsPos = (aNewAbsoluteContainingBlock &&
                        aNewAbsoluteContainingBlock->GetStyleDisplay()->HasTransform());
+
+  aNewAbsoluteContainingBlock->MarkAsAbsoluteContainingBlock();
 }
 
 void

layout/generic/nsFrame.cpp

@@ -128,6 +128,7 @@
 
 #include "gfxContext.h"
 #include "CSSCalc.h"
+#include "nsAbsoluteContainingBlock.h"
 
 using namespace mozilla;
 using namespace mozilla::layers;
@@ -258,6 +259,34 @@ nsFrame::RootFrameList(nsPresContext* aPresContext, FILE* out, PRInt32 aIndent)
 }
 #endif
 
+static void
+DestroyAbsoluteContainingBlock(void* aPropertyValue)
+{
+  delete static_cast<nsAbsoluteContainingBlock*>(aPropertyValue);
+}
+
+NS_DECLARE_FRAME_PROPERTY(AbsoluteContainingBlockProperty, DestroyAbsoluteContainingBlock)
+
+PRBool
+nsIFrame::HasAbsolutelyPositionedChildren() const {
+  return IsAbsoluteContainer() && GetAbsoluteContainingBlock()->HasAbsoluteFrames();
+}
+
+nsAbsoluteContainingBlock*
+nsIFrame::GetAbsoluteContainingBlock() const {
+  NS_ASSERTION(IsAbsoluteContainer(), "The frame is not marked as an abspos container correctly");
+  nsAbsoluteContainingBlock* absCB = static_cast<nsAbsoluteContainingBlock*>
+    (Properties().Get(AbsoluteContainingBlockProperty()));
+  NS_ASSERTION(absCB, "The frame is marked as an abspos container but doesn't have the property");
+  return absCB;
+}
+
+void
+nsIFrame::MarkAsAbsoluteContainingBlock() {
+  AddStateBits(NS_FRAME_HAS_ABSPOS_CHILDREN);
+  Properties().Set(AbsoluteContainingBlockProperty(), new nsAbsoluteContainingBlock(GetAbsoluteListName()));
+}
+
 void
 NS_MergeReflowStatusInto(nsReflowStatus* aPrimary, nsReflowStatus aSecondary)
 {

layout/generic/nsIFrame.h

@@ -103,6 +103,7 @@ class gfxSkipChars;
 class gfxSkipCharsIterator;
 class gfxContext;
 class nsLineList_iterator;
+class nsAbsoluteContainingBlock;
 
 struct nsPeekOffsetStruct;
 struct nsPoint;
@@ -285,6 +286,9 @@ typedef PRUint64 nsFrameState;
 // bit; we could free up this bit with a little extra complexity.
 #define NS_FRAME_UPDATE_LAYER_TREE                  NS_FRAME_STATE_BIT(36)
 
+// Frame can accept absolutely positioned children.
+#define NS_FRAME_HAS_ABSPOS_CHILDREN                NS_FRAME_STATE_BIT(37)
+
 // The lower 20 bits and upper 32 bits of the frame state are reserved
 // by this API.
 #define NS_FRAME_RESERVED                           ~NS_FRAME_IMPL_RESERVED
@@ -2699,7 +2703,17 @@ NS_PTR_TO_INT32(frame->Properties().Get(nsIFrame::EmbeddingLevelProperty()))
       }
     }
   }  
-  
+
+  /**
+   * Accessors for the absolute containing block.
+   */
+  PRBool IsAbsoluteContainer() const { return !!(mState & NS_FRAME_HAS_ABSPOS_CHILDREN); }
+  PRBool HasAbsolutelyPositionedChildren() const;
+  nsAbsoluteContainingBlock* GetAbsoluteContainingBlock() const;
+  virtual void MarkAsAbsoluteContainingBlock();
+  // Child frame types override this function to select their own child list name
+  virtual nsIAtom* GetAbsoluteListName() const { return nsGkAtoms::absoluteList; }
+
 protected:
   // Members
   nsRect           mRect;

layout/generic/nsViewportFrame.h

@@ -118,6 +118,9 @@ public:
   NS_IMETHOD GetFrameName(nsAString& aResult) const;
 #endif
 
+private:
+  virtual nsIAtom* GetAbsoluteListName() const { return nsGkAtoms::fixedList; }
+
 protected:
   nsPoint AdjustReflowStateForScrollbars(nsHTMLReflowState* aReflowState) const;