Expand PaintLayer clip to account for hidden URL bar with document.rootScroller

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
@@ skipping 10 matching lines @@
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #include "core/layout/LayoutBox.h"
 
 #include "core/dom/Document.h"
 #include "core/editing/EditingUtilities.h"
+#include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/input/EventHandler.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutAnalyzer.h"
 #include "core/layout/LayoutDeprecatedFlexibleBox.h"
 #include "core/layout/LayoutFlexibleBox.h"
 #include "core/layout/LayoutGrid.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutListMarker.h"
 #include "core/layout/LayoutMultiColumnFlowThread.h"
 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutTableCell.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/api/LayoutAPIShim.h"
 #include "core/layout/api/LayoutPartItem.h"
 #include "core/layout/api/LineLayoutBlockFlow.h"
 #include "core/layout/api/LineLayoutBox.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/layout/shapes/ShapeOutsideInfo.h"
+#include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/Page.h"
+#include "core/page/scrolling/RootScrollerController.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/page/scrolling/SnapCoordinator.h"
+#include "core/page/scrolling/TopDocumentRootScrollerController.h"
 #include "core/paint/BackgroundImageGeometry.h"
 #include "core/paint/BoxPaintInvalidator.h"
 #include "core/paint/BoxPainter.h"
 #include "core/paint/PaintLayer.h"
 #include "core/style/ShadowList.h"
 #include "platform/LengthFunctions.h"
 #include "platform/geometry/DoubleRect.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/FloatRoundedRect.h"
 #include "wtf/PtrUtil.h"
@@ skipping 1302 matching lines @@
   return std::max(LayoutUnit(), result);
 }
 
 // Hit Testing
 bool LayoutBox::nodeAtPoint(HitTestResult& result,
                             const HitTestLocation& locationInContainer,
                             const LayoutPoint& accumulatedOffset,
                             HitTestAction action) {
   LayoutPoint adjustedLocation = accumulatedOffset + location();
 
-  if (!isLayoutView()) {
+  if (this !=
+      document()
+          .rootScrollerController()
+          .effectiveRootScroller()
+          .layoutObject()) {
     // Check if we need to do anything at all.
     // If we have clipping, then we can't have any spillout.
     LayoutRect overflowBox =
         hasOverflowClip() ? borderBoxRect() : visualOverflowRect();
     flipForWritingMode(overflowBox);
     overflowBox.moveBy(adjustedLocation);
     if (!locationInContainer.intersects(overflowBox))
       return false;
   }
 
@@ skipping 389 matching lines @@
 }
 
 PaintInvalidationReason LayoutBox::invalidatePaintIfNeeded(
     const PaintInvalidatorContext& context) const {
   return BoxPaintInvalidator(*this, context).invalidatePaintIfNeeded();
 }
 
 LayoutRect LayoutBox::overflowClipRect(
     const LayoutPoint& location,
     OverlayScrollbarClipBehavior overlayScrollbarClipBehavior) const {
+  // If this box is the global root scroller, it's clip rect needs to match the
+  // viewport. This might be larger than the ordinary overflow rect since hiding
+  // the URL bar can expose more content without changing the box size.
+  if (FrameHost* host = document().frameHost()) {
+    Element* globalRootScroller =
+        host->globalRootScrollerController().globalRootScroller();
+    bool applySVGViewportClip =

[chrishtr, 2017/01/21 02:06:47]

overflowClipRect is a virtual method. You can put this in
LayoutSVGRoot.

+        isSVGRoot() && toLayoutSVGRoot(this)->shouldApplyViewportClip();
+    if (!applySVGViewportClip && node() && node() == globalRootScroller) {

[chrishtr, 2017/01/21 02:06:47]

Is it possible for the rootScroller to not have a PaintLayer? Doesn't
it have to be positioned or have overflow scroll?

+      LayoutView* topView = document().topDocument().layoutView();
+      // If the view rect is empty, LayoutView::overflowClipRect will fallback
+      // to the LayoutBox implementation so prevent infinitely recursing.
+      if (!topView->viewRect().isEmpty()) {

[chrishtr, 2017/01/21 02:06:47]

How about just adjusting overflowClipRect() for LayoutBox to know
how to do this instead? And possibly remove the code from LayoutView,
since with root-layer scrolling on the view acts more like a box.

+        return topView->overflowClipRect(location,
+                                         overlayScrollbarClipBehavior);
+      }
+    }
+  }
+
   // FIXME: When overflow-clip (CSS3) is implemented, we'll obtain the property
   // here.
   LayoutRect clipRect = borderBoxRect();
   clipRect.setLocation(location + clipRect.location() +
                        LayoutSize(borderLeft(), borderTop()));
   clipRect.setSize(clipRect.size() - LayoutSize(borderLeft() + borderRight(),
                                                 borderTop() + borderBottom()));
 
   if (hasOverflowClip())
     excludeScrollbars(clipRect, overlayScrollbarClipBehavior);
@@ skipping 3893 matching lines @@
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 bool LayoutBox::shouldClipOverflow() const {
   return hasOverflowClip() || styleRef().containsPaint() || hasControlClip();
 }
 
 }  // namespace blink