Bug 1697325 Part 5 - Add GetOverflowAreasRelativeToParent(), and simplify all the call sites. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D107740

layout/base/nsLayoutUtils.cpp

@@ -561,9 +561,7 @@ void nsLayoutUtils::UnionChildOverflow(nsIFrame* aFrame,
       continue;
     }
     for (nsIFrame* child : list) {
-      OverflowAreas childOverflow =
-          child->GetOverflowAreas() + child->GetPosition();
-      aOverflowAreas.UnionWith(childOverflow);
+      aOverflowAreas.UnionWith(child->GetOverflowAreasRelativeToParent());
     }
   }
 }

layout/generic/BlockReflowInput.cpp

@@ -865,8 +865,7 @@ bool BlockReflowInput::FlowAndPlaceFloat(nsIFrame* aFloat) {
 
   // Update the float combined area state
   // XXX Floats should really just get invalidated here if necessary
-  mFloatOverflowAreas.UnionWith(aFloat->GetOverflowAreas() +
-                                aFloat->GetPosition());
+  mFloatOverflowAreas.UnionWith(aFloat->GetOverflowAreasRelativeToParent());
 
   // Place the float in the float manager
   // calculate region

layout/generic/nsContainerFrame.cpp

@@ -2810,8 +2810,7 @@ void nsContainerFrame::ConsiderChildOverflow(OverflowAreas& aOverflowAreas,
     OverflowAreas combined = OverflowAreas(childVisual, nsRect());
     aOverflowAreas.UnionWith(combined + aChildFrame->GetPosition());
   } else {
-    aOverflowAreas.UnionWith(aChildFrame->GetOverflowAreas() +
-                             aChildFrame->GetPosition());
+    aOverflowAreas.UnionWith(aChildFrame->GetOverflowAreasRelativeToParent());
   }
 }
 

layout/generic/nsIFrame.cpp

@@ -7458,6 +7458,10 @@ OverflowAreas nsIFrame::GetOverflowAreasRelativeToSelf() const {
   return OverflowAreas(InkOverflowRect(), ScrollableOverflowRect());
 }
 
+OverflowAreas nsIFrame::GetOverflowAreasRelativeToParent() const {
+  return GetOverflowAreas() + mRect.TopLeft();
+}
+
 nsRect nsIFrame::ScrollableOverflowRectRelativeToParent() const {
   return ScrollableOverflowRect() + mRect.TopLeft();
 }

layout/generic/nsIFrame.h

@@ -3622,6 +3622,14 @@ class nsIFrame : public nsQueryFrame {
    */
   mozilla::OverflowAreas GetOverflowAreasRelativeToSelf() const;
 
+  /**
+   * Same as GetOverflowAreas, except relative to the parent frame.
+   *
+   * @return the overflow area relative to the parent frame, in the parent
+   * frame's coordinate system
+   */
+  mozilla::OverflowAreas GetOverflowAreasRelativeToParent() const;
+
   /**
    * Same as ScrollableOverflowRect, except relative to the parent
    * frame.