Add graphics layers for pinch virtual viewport.

Source/core/rendering/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 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 1101 matching lines @@
 void RenderLayerCompositor::frameViewDidChangeLocation(const IntPoint& contentsOffset)
 {
     if (m_overflowControlsHostLayer)
         m_overflowControlsHostLayer->setPosition(contentsOffset);
 }
 
 void RenderLayerCompositor::frameViewDidChangeSize()
 {
     if (m_clipLayer) {
         FrameView* frameView = m_renderView->frameView();
-        m_clipLayer->setSize(frameView->unscaledVisibleContentSize());
+        FloatSize visibleContentSize = frameView->unscaledVisibleContentSize();

[trchen, 2013/05/29 21:32:56]

FloatSize unscaledVisibleContentSize = ...

[wjmaclean, 2013/05/30 14:19:09]

Done.

+        m_clipLayer->setSize(visibleContentSize);
+        if (m_pinchVirtualViewportClipLayer) {

[trchen, 2013/05/29 21:32:56]

FloatSize visibleContentSize = unscaledVisibleContentSize;
visibleContentSize.scale(frameView->visibleContentScaleFactor());

[wjmaclean, 2013/05/30 14:19:09]

Done.

+            visibleContentSize.scale(frameView->visibleContentScaleFactor());
+            m_pinchVirtualViewportClipLayer->setSize(visibleContentSize);
+        }
 
         frameViewDidScroll();
         updateOverflowControlsLayers();
 
 #if ENABLE(RUBBER_BANDING)
         if (m_layerForOverhangAreas)
             m_layerForOverhangAreas->setSize(frameView->frameRect().size());
 #endif
     }
 }
@@ skipping 1253 matching lines @@
         m_clipLayer->setName("frame clipping");
 #endif
         m_clipLayer->setMasksToBounds(true);
 
         m_scrollLayer = GraphicsLayer::create(graphicsLayerFactory(), this);
 #ifndef NDEBUG
         m_scrollLayer->setName("frame scrolling");
 #endif
         if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
             scrollingCoordinator->setLayerIsContainerForFixedPositionLayers(m_scrollLayer.get(), true);
-
         // Hook them up
         m_overflowControlsHostLayer->addChild(m_clipLayer.get());
         m_clipLayer->addChild(m_scrollLayer.get());
-        m_scrollLayer->addChild(m_rootContentLayer.get());
+        if (isMainFrame() && m_renderView->document()->settings()->pinchVirtualViewportEnabled()) {

[enne (OOO), 2013/05/29 19:57:10]

Can you add a outline diagram in a comment here of what this hierarchy is
supposed to look like in terms of member variables and parent/child
relationships for both virtual viewport enabled and disabled?

[wjmaclean, 2013/05/29 21:00:30]

Will do.

+            m_pinchVirtualViewportClipLayer = GraphicsLayer::create(graphicsLayerFactory(), this);
+#ifndef NDEBUG
+            m_pinchVirtualViewportClipLayer->setName("pinch virtual viewport clip");
+#endif
+            m_pinchVirtualViewportClipLayer->setMasksToBounds(true);
+
+            m_pinchVirtualViewportScrollLayer = GraphicsLayer::create(graphicsLayerFactory(), this);
+#ifndef NDEBUG
+            m_pinchVirtualViewportScrollLayer->setName("pinch virtual viewport scroll");
+#endif
+
+            if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
+                scrollingCoordinator->setLayerIsContainerForFixedPositionLayers(m_pinchVirtualViewportScrollLayer.get(), true);
+
+            m_scrollLayer->addChild(m_pinchVirtualViewportClipLayer.get());
+            m_pinchVirtualViewportClipLayer->addChild(m_pinchVirtualViewportScrollLayer.get());
+            m_pinchVirtualViewportScrollLayer->addChild(m_rootContentLayer.get());

[trchen, 2013/05/29 21:32:56]

This doesn't look right. According to enne's design doc, the inner(pinch zoom)
viewport is supposed in a higher hierarchy than the outer(main frame) viewport.

And I'm still not convinced why this must belong to RLC. I weakly feel pinch
zoom should be a WebWidget concept, but I can be convinced otherwise. Either
way, at least we should make a separate helper class for it.

[wjmaclean, 2013/05/30 14:19:09]

The layer named m_pinchVirtualViewportScrollLayer here is the outer viewport, so
I think this matches the doc.

+        } else

[enne (OOO), 2013/05/29 19:57:10]

Can you add braces for this else to be in line with
https://codereview.chromium.org/15747011/ when it lands?

[wjmaclean, 2013/05/29 21:00:30]

Will do.

+            m_scrollLayer->addChild(m_rootContentLayer.get());
 
         frameViewDidChangeSize();
         frameViewDidScroll();
     }
 
     // Check to see if we have to change the attachment
     if (m_rootLayerAttachment != RootLayerUnattached)
         detachRootLayer();
 
     attachRootLayer(expectedAttachment);
@@ skipping 33 matching lines @@
 
     if (m_layerForScrollCorner) {
         m_layerForScrollCorner = nullptr;
         m_renderView->frameView()->invalidateScrollCorner(m_renderView->frameView()->scrollCornerRect());
     }
 
     if (m_overflowControlsHostLayer) {
         m_overflowControlsHostLayer = nullptr;
         m_clipLayer = nullptr;
         m_scrollLayer = nullptr;
+        m_pinchVirtualViewportClipLayer = nullptr;
+        m_pinchVirtualViewportScrollLayer = nullptr;
     }
     ASSERT(!m_scrollLayer);
     m_rootContentLayer = nullptr;
 }
 
 void RenderLayerCompositor::attachRootLayer(RootLayerAttachment attachment)
 {
     if (!m_rootContentLayer)
         return;
 
@@ skipping 263 matching lines @@
     return 0;
 }
 
 void RenderLayerCompositor::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, PlatformMemoryTypes::Rendering);
     info.addWeakPointer(m_renderView);
     info.addMember(m_rootContentLayer, "rootContentLayer");
     info.addMember(m_clipLayer, "clipLayer");
     info.addMember(m_scrollLayer, "scrollLayer");
+    info.addMember(m_pinchVirtualViewportClipLayer, "pinch virtual viewport clip layer");

[enne (OOO), 2013/05/29 19:57:10]

For consistency, maybe this should be pinchVirtualClipLayer and
pinchVirtualViewportScrollLayer?

[wjmaclean, 2013/05/29 21:00:30]

I'll rename everything to be inner/out as in the document, as per aelias'
suggestion.

+    info.addMember(m_pinchVirtualViewportScrollLayer, "pinch virtual viewport scroll layer");
     info.addMember(m_viewportConstrainedLayers, "viewportConstrainedLayers");
     info.addMember(m_overflowControlsHostLayer, "overflowControlsHostLayer");
     info.addMember(m_layerForHorizontalScrollbar, "layerForHorizontalScrollbar");
     info.addMember(m_layerForVerticalScrollbar, "layerForVerticalScrollbar");
     info.addMember(m_layerForScrollCorner, "layerForScrollCorner");
 #if ENABLE(RUBBER_BANDING)
     info.addMember(m_layerForOverhangAreas, "layerForOverhangAreas");
     info.addMember(m_contentShadowLayer, "contentShadowLayer");
     info.addMember(m_layerForTopOverhangArea, "layerForTopOverhangArea");
     info.addMember(m_layerForBottomOverhangArea, "layerForBottomOverhangArea");
 #endif
 }
 
 } // namespace WebCore