Introducing LayoutObject::mapToVisibleRectInContainerSpace

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 929 matching lines @@
 }
 
 void LayoutBox::applyCachedClipAndScrollOffsetForPaintInvalidation(LayoutRect& paintRect) const
 {
     ASSERT(hasLayer());
     ASSERT(hasOverflowClip());
 
     flipForWritingMode(paintRect);
     paintRect.move(-scrolledContentOffset()); // For overflow:auto/scroll/hidden.
 
-    // Do not clip scroll layer contents because the compositor expects the whole layer

[leviw_travelin_and_unemployed, 2015/12/09 23:06:26]

You said there's a use that prevents us from asserting don't cross a composited
scrolling boundary, no? Otherwise we should have that assert.

[szager1, 2015/12/09 23:21:26]

The use is IntersectionObserver :)

-    // to be always invalidated in-time.
-    if (usesCompositedScrolling()) {
-        flipForWritingMode(paintRect);
-        return;
-    }
-
     // size() is inaccurate if we're in the middle of a layout of this LayoutBox, so use the
     // layer's size instead. Even if the layer's size is wrong, the layer itself will issue paint invalidations
     // anyway if its size does change.
     LayoutRect clipRect(LayoutPoint(), LayoutSize(layer()->size()));
     paintRect = intersection(paintRect, clipRect);
     flipForWritingMode(paintRect);
 }
 
 void LayoutBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
@@ skipping 958 matching lines @@
         // Apply the relative position offset when invalidating a rectangle.  The layer
         // is translated, but the layout box isn't, so we need to do this to get the
         // right dirty rect.  Since this is called from LayoutObject::setStyle, the relative position
         // flag on the LayoutObject has been cleared, so use the one on the style().
         topLeft += layer()->offsetForInFlowPosition();
     }
 
     // FIXME: We ignore the lightweight clipping rect that controls use, since if |o| is in mid-layout,
     // its controlClipRect will be wrong. For overflow clip we use the values cached by the layer.
     rect.setLocation(topLeft);
-    if (o->hasOverflowClip()) {
+    if (o != paintInvalidationContainer && o->hasOverflowClip()) {

[leviw_travelin_and_unemployed, 2015/12/09 23:06:26]

May be worthy of a comment?

[szager1, 2015/12/09 23:21:26]

I'm not exactly sure what the comment should be.  I could copy the comment which
I deleted from applyCachedClipAndScrollOffsetForPaintInvalidation, but that kind
of obscures the fact that we actually do this because it's what works for the
two known applications of this method.  Maybe just a top-level comment on the
method that describe what it does?

         LayoutBox* containerBox = toLayoutBox(o);
         containerBox->applyCachedClipAndScrollOffsetForPaintInvalidation(rect);
         if (rect.isEmpty())
             return;
     }
 
     if (containerSkipped) {
         // If the paintInvalidationContainer is below o, then we need to map the rect into paintInvalidationContainer's coordinates.
         LayoutSize containerOffset = paintInvalidationContainer->offsetFromAncestorContainer(o);
         rect.move(-containerOffset);
@@ skipping 2911 matching lines @@
 }
 
 void LayoutBox::clearPreviousPaintInvalidationRects()
 {
     LayoutBoxModelObject::clearPreviousPaintInvalidationRects();
     if (PaintLayerScrollableArea* scrollableArea = this->scrollableArea())
         scrollableArea->clearPreviousPaintInvalidationRects();
 }
 
 } // namespace blink