Adds DevTools commands for forced viewport override.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 2264 matching lines @@
     if (!scrollbar)
         return;
 
     const IntRect& scrollbarRect = scrollbar->frameRect();
     TransformRecorder transformRecorder(context, *scrollbar, AffineTransform::translation(-scrollbarRect.x(), -scrollbarRect.y()));
     IntRect transformedClip = clip;
     transformedClip.moveBy(scrollbarRect.location());
     scrollbar->paint(context, CullRect(transformedClip));
 }
 
+// TODO(eseckler): Make recording distance configurable, e.g. for use in
+// headless, where we would like to record an exact area (distance = 0).
 static const int kPixelDistanceToRecord = 4000;
 
 IntRect CompositedLayerMapping::recomputeInterestRect(const GraphicsLayer* graphicsLayer) const
 {
     FloatRect graphicsLayerBounds(FloatPoint(), graphicsLayer->size());
 
     IntSize offsetFromAnchorLayoutObject;
     const LayoutBoxModelObject* anchorLayoutObject;
     if (graphicsLayer == m_squashingLayer.get()) {
         // TODO(chrishtr): this is a speculative fix for crbug.com/561306. However, it should never be the case that
@@ skipping 10 matching lines @@
         anchorLayoutObject = m_owningLayer.layoutObject();
         offsetFromAnchorLayoutObject = graphicsLayer->offsetFromLayoutObject();
         adjustForCompositedScrolling(graphicsLayer, offsetFromAnchorLayoutObject);
     }
 
     // Start with the bounds of the graphics layer in the space of the anchor LayoutObject.
     FloatRect graphicsLayerBoundsInObjectSpace(graphicsLayerBounds);
     graphicsLayerBoundsInObjectSpace.move(offsetFromAnchorLayoutObject);
 
     // Now map the bounds to its visible content rect in screen space, including applying clips along the way.
-    LayoutRect visibleContentRect(graphicsLayerBoundsInObjectSpace);
+    LayoutRect graphicsLayerBoundsInScreenSpace(graphicsLayerBoundsInObjectSpace);

[chrishtr, 2016/08/22 22:00:42]

It's not screen space, it's the space of the root LayoutView. i.e. it doesn't
include scrolling.

[Eric Seckler, 2016/08/23 09:32:19]

Makes sense, updated the comments as well.

     LayoutView* rootView = anchorLayoutObject->view();
     while (rootView->frame()->ownerLayoutObject())
         rootView = rootView->frame()->ownerLayoutObject()->view();
-    anchorLayoutObject->mapToVisualRectInAncestorSpace(rootView, visibleContentRect);
-    visibleContentRect.intersect(LayoutRect(rootView->frameView()->visibleContentRect()));
+    anchorLayoutObject->mapToVisualRectInAncestorSpace(rootView, graphicsLayerBoundsInScreenSpace);
+    FloatRect visibleContentRect(graphicsLayerBoundsInScreenSpace);
+    rootView->frameView()->clipPaintRect(&visibleContentRect);
 
     IntRect enclosingGraphicsLayerBounds(enclosingIntRect(graphicsLayerBounds));
 
     // Map the visible content rect from screen space to local graphics layer space.
     IntRect localInterestRect;
     // If the visible content rect is empty, then it makes no sense to map it back since there is nothing to map.
     if (!visibleContentRect.isEmpty()) {
-        localInterestRect = anchorLayoutObject->absoluteToLocalQuad(FloatRect(visibleContentRect), UseTransforms | TraverseDocumentBoundaries).enclosingBoundingBox();
+        localInterestRect = anchorLayoutObject->absoluteToLocalQuad(visibleContentRect, UseTransforms | TraverseDocumentBoundaries).enclosingBoundingBox();
         localInterestRect.move(-offsetFromAnchorLayoutObject);
         // TODO(chrishtr): the code below is a heuristic, instead we should detect and return whether the mapping failed.
         // In some cases, absoluteToLocalQuad can fail to map back to the local space, due to passing through
         // non-invertible transforms or floating-point accuracy issues. Examples include rotation near 90 degrees
         // or perspective. In such cases, fall back to painting the first kPixelDistanceToRecord pixels in each direction.
         localInterestRect.intersect(enclosingGraphicsLayerBounds);
     }
     // Expand by interest rect padding amount.
     localInterestRect.inflate(kPixelDistanceToRecord);
     localInterestRect.intersect(enclosingGraphicsLayerBounds);
@@ skipping 34 matching lines @@
     return false;
 }
 
 IntRect CompositedLayerMapping::computeInterestRect(const GraphicsLayer* graphicsLayer, const IntRect& previousInterestRect) const
 {
     // Use the previous interest rect if it covers the whole layer.
     IntRect wholeLayerRect = IntRect(IntPoint(), expandedIntSize(graphicsLayer->size()));
     if (!needsRepaint(*graphicsLayer) && previousInterestRect == wholeLayerRect)
         return previousInterestRect;
 
     // Paint the whole layer if "mainFrameClipsContent" is false, meaning that WebPreferences::record_whole_document is true.

[dgozman, 2016/08/22 22:22:06]

I'd suggest to unify this setting with clipPaintRect being implemented in
FrameView in a separate patch before using it here. If I understand things
correctly, FrameView could clip to mainFrame when setting is true, and to
viewport size (as in this patch) when it's false. WDYT?

     bool shouldPaintWholePage = !m_owningLayer.layoutObject()->document().settings()->mainFrameClipsContent();
     if (shouldPaintWholePage
         || (graphicsLayer != m_graphicsLayer.get() && graphicsLayer != m_squashingLayer.get() && graphicsLayer != m_scrollingContentsLayer.get()))
         return wholeLayerRect;
 
     IntRect newInterestRect = recomputeInterestRect(graphicsLayer);
     if (interestRectChangedEnoughToRepaint(previousInterestRect, newInterestRect, expandedIntSize(graphicsLayer->size())))
         return newInterestRect;
     return previousInterestRect;
 }
@@ skipping 297 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink