Pinch/Zoom Infrastructure & Plumbing CL (Prequel)

Source/web/PinchViewports.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 45 matching lines @@
 }
 
 PinchViewports::PinchViewports(WebViewImpl* owner)
     : m_owner(owner)
     , m_innerViewportContainerLayer(GraphicsLayer::create(m_owner->graphicsLayerFactory(), this))
     , m_pageScaleLayer(GraphicsLayer::create(m_owner->graphicsLayerFactory(), this))
     , m_innerViewportScrollLayer(GraphicsLayer::create(m_owner->graphicsLayerFactory(), this))
     , m_overlayScrollbarHorizontal(GraphicsLayer::create(m_owner->graphicsLayerFactory(), this))
     , m_overlayScrollbarVertical(GraphicsLayer::create(m_owner->graphicsLayerFactory(), this))
 {
-    m_innerViewportContainerLayer->platformLayer()->setIsContainerForFixedPositionLayers(true);
+    ASSERT(m_owner);
+    WebCore::ScrollingCoordinator* coordinator = m_owner->page()->scrollingCoordinator();
+    ASSERT(coordinator);
+    coordinator->setLayerIsContainerForFixedPositionLayers(m_innerViewportScrollLayer.get(), true);
+
     // No need for the inner viewport to clip, since the compositing
     // surface takes care of it -- and clipping here would interfere with
     // dynamically-sized viewports on Android.
     m_innerViewportContainerLayer->setMasksToBounds(false);
 
+    // TODO(wjmaclean) Remove next line once https://codereview.chromium.org/23983047 lands.
     m_innerViewportScrollLayer->platformLayer()->setScrollable(true);
+    m_innerViewportScrollLayer->platformLayer()->setScrollClipLayer(
+        m_innerViewportContainerLayer->platformLayer());
     m_innerViewportScrollLayer->platformLayer()->setUserScrollable(true, true);
 
     m_innerViewportContainerLayer->addChild(m_pageScaleLayer.get());
     m_pageScaleLayer->addChild(m_innerViewportScrollLayer.get());
     m_innerViewportContainerLayer->addChild(m_overlayScrollbarHorizontal.get());
     m_innerViewportContainerLayer->addChild(m_overlayScrollbarVertical.get());
 
     // Setup the inner viewport overlay scrollbars.
     setupScrollbar(WebScrollbar::Horizontal);
     setupScrollbar(WebScrollbar::Vertical);
 }
 
 PinchViewports::~PinchViewports() { }
 
 void PinchViewports::setViewportSize(const WebCore::IntSize& newSize)
 {
     m_innerViewportContainerLayer->setSize(newSize);
+    // The innerviewport scroll layer always has the same size as its clip layer, but
+    // the page scale layer lives between them, allowing for non-zero max scroll
+    // offset when page scale > 1.
+    m_innerViewportScrollLayer->setSize(newSize);
 
     // Need to re-compute sizes for the overlay scrollbars.
     setupScrollbar(WebScrollbar::Horizontal);
     setupScrollbar(WebScrollbar::Vertical);
 }
 
 // Modifies the top of the graphics layer tree to add layers needed to support
 // the inner/outer viewport fixed-position model for pinch zoom. When finished,
 // the tree will look like this (with * denoting added layers):
 //
@@ skipping 43 matching lines @@
         m_webOverlayScrollbarHorizontal : m_webOverlayScrollbarVertical;
 
     const int overlayScrollbarThickness = m_owner->settingsImpl()->pinchOverlayScrollbarThickness();
 
     if (!webScrollbarLayer) {
         WebCore::ScrollingCoordinator* coordinator = m_owner->page()->scrollingCoordinator();
         ASSERT(coordinator);
         WebCore::ScrollbarOrientation webcoreOrientation = isHorizontal ? WebCore::HorizontalScrollbar : WebCore::VerticalScrollbar;
         webScrollbarLayer = coordinator->createSolidColorScrollbarLayer(webcoreOrientation, overlayScrollbarThickness, false);
 
-        webScrollbarLayer->setScrollLayer(m_innerViewportScrollLayer->platformLayer());
+        webScrollbarLayer->setClipLayer(m_innerViewportContainerLayer->platformLayer());
         scrollbarGraphicsLayer->setContentsToPlatformLayer(webScrollbarLayer->layer());
         scrollbarGraphicsLayer->setDrawsContent(false);
     }
 
     int xPosition = isHorizontal ? 0 : m_innerViewportContainerLayer->size().width() - overlayScrollbarThickness;
     int yPosition = isHorizontal ? m_innerViewportContainerLayer->size().height() - overlayScrollbarThickness : 0;
     int width = isHorizontal ? m_innerViewportContainerLayer->size().width() - overlayScrollbarThickness : overlayScrollbarThickness;
     int height = isHorizontal ? overlayScrollbarThickness : m_innerViewportContainerLayer->size().height() - overlayScrollbarThickness;
 
+    // Use the GraphicsLayer to position the scrollbars.
     scrollbarGraphicsLayer->setPosition(WebCore::IntPoint(xPosition, yPosition));
     scrollbarGraphicsLayer->setSize(WebCore::IntSize(width, height));
+    scrollbarGraphicsLayer->contentsLayer()->setBounds(WebSize(width, height));

[jamesr, 2014/01/14 22:48:58]

don't you actually want to call GraphicsLayer::setContentsRect() here?

[wjmaclean, 2014/01/14 23:55:29]

Hmm, yes, that seems better!

 }
 
 void PinchViewports::registerViewportLayersWithTreeView(WebLayerTreeView* layerTreeView) const
 {
     ASSERT(layerTreeView);
 
     WebCore::RenderLayerCompositor* compositor = m_owner->compositor();
-    GraphicsLayer* scrollLayer = compositor->scrollLayer();
+    // Get the outer viewport scroll layer.
+    WebLayer* scrollLayer = compositor->scrollLayer()->platformLayer();
+
+    m_webOverlayScrollbarHorizontal->setScrollLayer(scrollLayer);
+    m_webOverlayScrollbarVertical->setScrollLayer(scrollLayer);
 
     ASSERT(compositor);
     layerTreeView->registerViewportLayers(
         m_pageScaleLayer->platformLayer(),
         m_innerViewportScrollLayer->platformLayer(),
-        scrollLayer->platformLayer());
+        scrollLayer);
 }
 
 void PinchViewports::clearViewportLayersForTreeView(WebLayerTreeView* layerTreeView) const
 {
     ASSERT(layerTreeView);
 
     layerTreeView->clearViewportLayers();
 }
 
 void PinchViewports::notifyAnimationStarted(const GraphicsLayer*, double wallClockTime, double monotonicTime)
@@ skipping 18 matching lines @@
     } else if (graphicsLayer == m_overlayScrollbarVertical.get()) {
         name =  "Overlay Scrollbar Vertical Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink