Bug 1202029 - Use the containing block for determining perspective for transformed elements. r=dbaron

layout/base/nsDisplayList.cpp

@@ -4811,19 +4811,12 @@ nsDisplayTransform::GetDeltaToPerspectiveOrigin(const nsIFrame* aFrame,
 
   //TODO: Should this be using our bounds or the parent's bounds?
   // How do we handle aBoundsOverride in the latter case?
-  nsIFrame* parent;
-  nsStyleContext* psc = aFrame->GetParentStyleContext(&parent);
-  if (!psc) {
+  nsIFrame* cbFrame = aFrame->GetContainingBlock(nsIFrame::SKIP_SCROLLED_FRAME);
+  if (!cbFrame) {
     return Point3D();
   }
-  if (!parent) {
-    parent = aFrame->GetParent();
-    if (!parent) {
-      return Point3D();
-    }
-  }
-  const nsStyleDisplay* display = psc->StyleDisplay();
-  TransformReferenceBox refBox(parent);
+  const nsStyleDisplay* display = cbFrame->StyleDisplay();
+  TransformReferenceBox refBox(cbFrame);
 
   /* Allows us to access named variables by index. */
   Point3D result;
@@ -4854,7 +4847,7 @@ nsDisplayTransform::GetDeltaToPerspectiveOrigin(const nsIFrame* aFrame,
     }
   }
 
-  nsPoint parentOffset = aFrame->GetOffsetTo(parent);
+  nsPoint parentOffset = aFrame->GetOffsetTo(cbFrame);
   Point3D gfxOffset(
             NSAppUnitsToFloatPixels(parentOffset.x, aAppUnitsPerPixel),
             NSAppUnitsToFloatPixels(parentOffset.y, aAppUnitsPerPixel),
@@ -4871,17 +4864,16 @@ nsDisplayTransform::FrameTransformProperties::FrameTransformProperties(const nsI
   , mToTransformOrigin(GetDeltaToTransformOrigin(aFrame, aAppUnitsPerPixel, aBoundsOverride))
   , mChildPerspective(0)
 {
-  const nsStyleDisplay* parentDisp = nullptr;
-  nsStyleContext* parentStyleContext = aFrame->StyleContext()->GetParent();
-  if (parentStyleContext) {
-    parentDisp = parentStyleContext->StyleDisplay();
-  }
-  if (parentDisp && parentDisp->mChildPerspective.GetUnit() == eStyleUnit_Coord) {
-    mChildPerspective = parentDisp->mChildPerspective.GetCoordValue();
-    // Calling GetDeltaToPerspectiveOrigin can be expensive, so we avoid
-    // calling it unnecessarily.
-    if (mChildPerspective > 0.0) {
-      mToPerspectiveOrigin = GetDeltaToPerspectiveOrigin(aFrame, aAppUnitsPerPixel);
+  nsIFrame* cbFrame = aFrame->GetContainingBlock(nsIFrame::SKIP_SCROLLED_FRAME);
+  if (cbFrame) {
+    const nsStyleDisplay* display = cbFrame->StyleDisplay();
+    if (display->mChildPerspective.GetUnit() == eStyleUnit_Coord) {
+      mChildPerspective = display->mChildPerspective.GetCoordValue();
+      // Calling GetDeltaToPerspectiveOrigin can be expensive, so we avoid
+      // calling it unnecessarily.
+      if (mChildPerspective > 0.0) {
+        mToPerspectiveOrigin = GetDeltaToPerspectiveOrigin(aFrame, aAppUnitsPerPixel);
+      }
     }
   }
 }

layout/base/nsLayoutUtils.cpp

@@ -4190,19 +4190,15 @@ GetPercentBSize(const nsStyleCoord& aStyle,
   MOZ_ASSERT(!aStyle.IsCalcUnit() || aStyle.CalcHasPercent(),
              "GetAbsoluteCoord should have handled this");
 
-  nsIFrame *f = aFrame->GetContainingBlock();
-  if (!f) {
-    NS_NOTREACHED("top of frame tree not a containing block");
-    return false;
-  }
-
   // During reflow, nsHTMLScrollFrame::ReflowScrolledFrame uses
   // SetComputedHeight on the reflow state for its child to propagate its
   // computed height to the scrolled content. So here we skip to the scroll
   // frame that contains this scrolled content in order to get the same
   // behavior as layout when computing percentage heights.
-  if (f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::scrolledContent) {
-    f = f->GetParent();
+  nsIFrame *f = aFrame->GetContainingBlock(nsIFrame::SKIP_SCROLLED_FRAME);
+  if (!f) {
+    NS_NOTREACHED("top of frame tree not a containing block");
+    return false;
   }
 
   WritingMode wm = f->GetWritingMode();

layout/generic/nsFrame.cpp

@@ -1143,12 +1143,11 @@ nsIFrame::HasPerspective() const
   if (!IsTransformed()) {
     return false;
   }
-  nsStyleContext* parentStyleContext = StyleContext()->GetParent();
-  if (!parentStyleContext) {
+  nsIFrame* containingBlock = GetContainingBlock(SKIP_SCROLLED_FRAME);
+  if (!containingBlock) {
     return false;
   }
-  const nsStyleDisplay* parentDisp = parentStyleContext->StyleDisplay();
-  return parentDisp->mChildPerspective.GetUnit() == eStyleUnit_Coord;
+  return containingBlock->ChildrenHavePerspective();
 }
 
 bool
@@ -5705,16 +5704,27 @@ GetNearestBlockContainer(nsIFrame* frame)
 }
 
 nsIFrame*
-nsIFrame::GetContainingBlock() const
+nsIFrame::GetContainingBlock(uint32_t aFlags) const
 {
+  if (!GetParent()) {
+    return nullptr;
+  }
   // MathML frames might have absolute positioning style, but they would
   // still be in-flow.  So we have to check to make sure that the frame
   // is really out-of-flow too.
+  nsIFrame* f;
   if (IsAbsolutelyPositioned() &&
       (GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
-    return GetParent(); // the parent is always the containing block
+    f = GetParent(); // the parent is always the containing block
+  } else {
+    f = GetNearestBlockContainer(GetParent());
   }
-  return GetNearestBlockContainer(GetParent());
+
+  if (aFlags & SKIP_SCROLLED_FRAME && f &&
+      f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::scrolledContent) {
+    f = f->GetParent();
+  }
+  return f;
 }
 
 #ifdef DEBUG_FRAME_DUMP
@@ -7632,7 +7642,7 @@ nsIFrame::FinishAndStoreOverflow(nsOverflowAreas& aOverflowAreas,
   nsRect bounds(nsPoint(0, 0), aNewSize);
   // Store the passed in overflow area if we are a preserve-3d frame or we have
   // a transform, and it's not just the frame bounds.
-  if (Preserves3D() || HasPerspective() || IsTransformed()) {
+  if (Preserves3D() || IsTransformed()) {
     if (!aOverflowAreas.VisualOverflow().IsEqualEdges(bounds) ||
         !aOverflowAreas.ScrollableOverflow().IsEqualEdges(bounds)) {
       nsOverflowAreas* initial =
@@ -7748,13 +7758,13 @@ nsIFrame::FinishAndStoreOverflow(nsOverflowAreas& aOverflowAreas,
     if (Preserves3DChildren()) {
       ComputePreserve3DChildrenOverflow(aOverflowAreas, newBounds);
     } else if (sizeChanged && ChildrenHavePerspective()) {
-      RecomputePerspectiveChildrenOverflow(this->StyleContext(), &newBounds);
+      RecomputePerspectiveChildrenOverflow(this, &newBounds);
     }
   } else {
     Properties().Delete(nsIFrame::PreTransformOverflowAreasProperty());
     if (ChildrenHavePerspective() && sizeChanged) {
       nsRect newBounds(nsPoint(0, 0), aNewSize);
-      RecomputePerspectiveChildrenOverflow(this->StyleContext(), &newBounds);
+      RecomputePerspectiveChildrenOverflow(this, &newBounds);
     }
   }
 
@@ -7772,7 +7782,7 @@ nsIFrame::FinishAndStoreOverflow(nsOverflowAreas& aOverflowAreas,
 }
 
 void
-nsIFrame::RecomputePerspectiveChildrenOverflow(const nsStyleContext* aStartStyle, const nsRect* aBounds)
+nsIFrame::RecomputePerspectiveChildrenOverflow(const nsIFrame* aStartFrame, const nsRect* aBounds)
 {
   // Children may check our size when getting our transform, make sure it's valid.
   nsSize oldSize = GetSize();
@@ -7799,14 +7809,13 @@ nsIFrame::RecomputePerspectiveChildrenOverflow(const nsStyleContext* aStartStyle
           boundsOverflow.SetAllTo(bounds);
           child->FinishAndStoreOverflow(boundsOverflow, bounds.Size());
         }
-      } else if (child->StyleContext()->GetParent() == aStartStyle ||
-                 child->StyleContext() == aStartStyle) {
+      } else if (child->GetContainingBlock(SKIP_SCROLLED_FRAME) == aStartFrame) {
         // If a frame is using perspective, then the size used to compute
         // perspective-origin is the size of the frame belonging to its parent
         // style context. We must find any descendant frames using our size
-        // (by recurse into frames with the same style context, or a direct
-        // child style context) to update their overflow rects too.
-        child->RecomputePerspectiveChildrenOverflow(aStartStyle, nullptr);
+        // (by recursing into frames that have the same containing block)
+        // to update their overflow rects too.
+        child->RecomputePerspectiveChildrenOverflow(aStartFrame, nullptr);
       }
     }
   }

layout/generic/nsGfxScrollFrame.cpp

@@ -2471,7 +2471,7 @@ ScrollFrameHelper::ScrollToImpl(nsPoint aPt, const nsRect& aRange, nsIAtom* aOri
   if (mOuter->ChildrenHavePerspective()) {
     // The overflow areas of descendants may depend on the scroll position,
     // so ensure they get updated.
-    mOuter->RecomputePerspectiveChildrenOverflow(mOuter->StyleContext(), nullptr);
+    mOuter->RecomputePerspectiveChildrenOverflow(mOuter, nullptr);
   }
 
   ScheduleSyntheticMouseMove();

layout/generic/nsIFrame.h

@@ -1267,7 +1267,7 @@ public:
   // Calculate the overflow size of all child frames, taking preserve-3d into account
   void ComputePreserve3DChildrenOverflow(nsOverflowAreas& aOverflowAreas, const nsRect& aBounds);
 
-  void RecomputePerspectiveChildrenOverflow(const nsStyleContext* aStartStyle, const nsRect* aBounds);
+  void RecomputePerspectiveChildrenOverflow(const nsIFrame* aStartFrame, const nsRect* aBounds);
 
   /**
    * Returns the number of ancestors between this and the root of our frame tree
@@ -2116,8 +2116,18 @@ public:
    *
    * NOTE: This is guaranteed to return a non-null pointer when invoked on any
    * frame other than the root frame.
+   *
+   * Requires SKIP_SCROLLED_FRAME to get behaviour matching the spec, otherwise
+   * it can return anonymous inner scrolled frames. Bug 1204044 is filed for
+   * investigating whether any of the callers actually require the default
+   * behaviour.
    */
-  nsIFrame* GetContainingBlock() const;
+  enum {
+    // If the containing block is an anonymous scrolled frame, then skip over
+    // this and return the outer scroll frame.
+    SKIP_SCROLLED_FRAME = 0x01
+  };
+  nsIFrame* GetContainingBlock(uint32_t aFlags = 0) const;
 
   /**
    * Is this frame a containing block for floating elements?