Make nsLineBox track two separate overflow areas. (Bug 542595, patch 6) r=roc a2.0=blocking2.0:beta8

layout/generic/nsLineBox.cpp

@@ -206,9 +206,15 @@ nsLineBox::List(FILE* out, PRInt32 aIndent) const
   fprintf(out, "{%d,%d,%d,%d} ",
           mBounds.x, mBounds.y, mBounds.width, mBounds.height);
   if (mData) {
-    fprintf(out, "ca={%d,%d,%d,%d} ",
-            mData->mCombinedArea.x, mData->mCombinedArea.y,
-            mData->mCombinedArea.width, mData->mCombinedArea.height);
+    fprintf(out, "vis-overflow={%d,%d,%d,%d} scr-overflow={%d,%d,%d,%d} ",
+            mData->mOverflowAreas.VisualOverflow().x,
+            mData->mOverflowAreas.VisualOverflow().y,
+            mData->mOverflowAreas.VisualOverflow().width,
+            mData->mOverflowAreas.VisualOverflow().height,
+            mData->mOverflowAreas.ScrollableOverflow().x,
+            mData->mOverflowAreas.ScrollableOverflow().y,
+            mData->mOverflowAreas.ScrollableOverflow().width,
+            mData->mOverflowAreas.ScrollableOverflow().height);
   }
   fprintf(out, "<\n");
 
@@ -419,7 +425,7 @@ nsLineBox::SetCarriedOutBottomMargin(nsCollapsingMargin aValue)
 void
 nsLineBox::MaybeFreeData()
 {
-  if (mData && (mData->mCombinedArea == mBounds)) {
+  if (mData && mData->mOverflowAreas == nsOverflowAreas(mBounds, mBounds)) {
     if (IsInline()) {
       if (mInlineData->mFloats.IsEmpty()) {
         delete mInlineData;
@@ -489,29 +495,31 @@ nsLineBox::RemoveFloat(nsIFrame* aFrame)
 }
 
 void
-nsLineBox::SetCombinedArea(const nsRect& aCombinedArea)
-{  
-  NS_ASSERTION(aCombinedArea.width >= 0, "illegal width for combined area");
-  NS_ASSERTION(aCombinedArea.height >= 0, "illegal height for combined area");
-  if (aCombinedArea != mBounds) {
-    if (mData) {
-      mData->mCombinedArea = aCombinedArea;
-    }
-    else {
+nsLineBox::SetOverflowAreas(const nsOverflowAreas& aOverflowAreas)
+{
+  NS_FOR_FRAME_OVERFLOW_TYPES(otype) {
+    NS_ASSERTION(aOverflowAreas.Overflow(otype).width >= 0,
+                 "illegal width for combined area");
+    NS_ASSERTION(aOverflowAreas.Overflow(otype).height >= 0,
+                 "illegal height for combined area");
+  }
+  // REVIEW: should this use IsExactEqual?
+  if (aOverflowAreas.VisualOverflow() != mBounds ||
+      aOverflowAreas.ScrollableOverflow() != mBounds) {
+    if (!mData) {
       if (IsInline()) {
-        mInlineData = new ExtraInlineData(aCombinedArea);
+        mInlineData = new ExtraInlineData(mBounds);
       }
       else {
-        mBlockData = new ExtraBlockData(aCombinedArea);
+        mBlockData = new ExtraBlockData(mBounds);
       }
     }
+    mData->mOverflowAreas = aOverflowAreas;
   }
-  else {
-    if (mData) {
-      // Store away new value so that MaybeFreeData compares against
-      // the right value.
-      mData->mCombinedArea = aCombinedArea;
-    }
+  else if (mData) {
+    // Store away new value so that MaybeFreeData compares against
+    // the right value.
+    mData->mOverflowAreas = aOverflowAreas;
     MaybeFreeData();
   }
 }

layout/generic/nsLineBox.h

@@ -410,15 +410,27 @@ public:
   // overflow area of its parent block.  The combined area should be
   // used for painting-related things, but should never be used for
   // layout (except for handling of 'overflow').
-  void SetCombinedArea(const nsRect& aCombinedArea);
-  nsRect GetCombinedArea() {
-    return mData ? mData->mCombinedArea : mBounds;
+  void SetOverflowAreas(const nsOverflowAreas& aOverflowAreas);
+  nsRect GetOverflowArea(nsOverflowType aType) {
+    return mData ? mData->mOverflowAreas.Overflow(aType) : mBounds;
   }
+  nsOverflowAreas GetOverflowAreas() {
+    if (mData) {
+      return mData->mOverflowAreas;
+    }
+    return nsOverflowAreas(mBounds, mBounds);
+  }
+  nsRect GetVisualOverflowArea()
+    { return GetOverflowArea(eVisualOverflow); }
+  nsRect GetScrollableOverflowArea()
+    { return GetOverflowArea(eScrollableOverflow); }
 
   void SlideBy(nscoord aDY) {
     mBounds.y += aDY;
     if (mData) {
-      mData->mCombinedArea.y += aDY;
+      NS_FOR_FRAME_OVERFLOW_TYPES(otype) {
+        mData->mOverflowAreas.Overflow(otype).y += aDY;
+      }
     }
   }
 
@@ -517,9 +529,9 @@ public:
   };
 
   struct ExtraData {
-    ExtraData(const nsRect& aBounds) : mCombinedArea(aBounds) {
+    ExtraData(const nsRect& aBounds) : mOverflowAreas(aBounds, aBounds) {
     }
-    nsRect mCombinedArea;
+    nsOverflowAreas mOverflowAreas;
   };
 
   struct ExtraBlockData : public ExtraData {