Add ability to create solid color scrollbars in ScrollingCoordinator.

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 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 16 matching lines @@
 
 #include "core/page/scrolling/ScrollingCoordinator.h"
 
 #include "RuntimeEnabledFeatures.h"
 #include "core/dom/Document.h"
 #include "core/dom/Node.h"
 #include "core/html/HTMLElement.h"
 #include "core/page/Frame.h"
 #include "core/page/FrameView.h"
 #include "core/page/Page.h"
+#include "core/page/Settings.h"
 #include "core/platform/PlatformWheelEvent.h"
 #include "core/platform/ScrollAnimator.h"
 #include "core/platform/ScrollbarTheme.h"
 #include "core/platform/chromium/TraceEvent.h"
 #include "core/platform/chromium/support/WebScrollbarImpl.h"
 #include "core/platform/chromium/support/WebScrollbarThemeGeometryNative.h"
 #include "core/platform/graphics/GraphicsLayer.h"
 #include "core/platform/graphics/IntRect.h"
 #include "core/platform/graphics/Region.h"
 #include "core/platform/graphics/transforms/TransformState.h"
@@ skipping 154 matching lines @@
 {
     ScrollbarTheme* theme = scrollbar->theme();
     WebKit::WebScrollbarThemePainter painter(theme, scrollbar);
     OwnPtr<WebKit::WebScrollbarThemeGeometry> geometry(WebKit::WebScrollbarThemeGeometryNative::create(theme));
 
     OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(WebKit::Platform::current()->compositorSupport()->createScrollbarLayer(new WebKit::WebScrollbarImpl(scrollbar), painter, geometry.leakPtr()));
     GraphicsLayer::registerContentsLayer(scrollbarLayer->layer());
     return scrollbarLayer.release();
 }
 
+PassOwnPtr<WebScrollbarLayer> ScrollingCoordinator::createSolidColorScrollbarLayer(ScrollbarOrientation orientation, int thumbThickness)
+{
+    WebKit::WebScrollbar::Orientation webOrientation = (orientation == HorizontalScrollbar) ? WebKit::WebScrollbar::Horizontal : WebKit::WebScrollbar::Vertical;
+    OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(WebKit::Platform::current()->compositorSupport()->createSolidColorScrollbarLayer(webOrientation, thumbThickness));
+    return scrollbarLayer.release();
+}
+
 static void detachScrollbarLayer(GraphicsLayer* scrollbarGraphicsLayer)
 {
     ASSERT(scrollbarGraphicsLayer);
 
     scrollbarGraphicsLayer->setContentsToPlatformLayer(0);
     scrollbarGraphicsLayer->setDrawsContent(true);
 }
 
 static void setupScrollbarLayer(GraphicsLayer* scrollbarGraphicsLayer, WebScrollbarLayer* scrollbarLayer, WebLayer* scrollLayer)
 {
@@ skipping 43 matching lines @@
 
     GraphicsLayer* scrollbarGraphicsLayer = orientation == HorizontalScrollbar ? horizontalScrollbarLayerForScrollableArea(scrollableArea) : verticalScrollbarLayerForScrollableArea(scrollableArea);
     if (scrollbarGraphicsLayer) {
         Scrollbar* scrollbar = orientation == HorizontalScrollbar ? scrollableArea->horizontalScrollbar() : scrollableArea->verticalScrollbar();
         if (scrollbar->isCustomScrollbar()) {
             detachScrollbarLayer(scrollbarGraphicsLayer);
             return;
         }
 
         WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, orientation);
-        if (!scrollbarLayer)
-            scrollbarLayer = addWebScrollbarLayer(scrollableArea, orientation, createScrollbarLayer(scrollbar));
+        if (!scrollbarLayer) {
+            Settings* settings = m_page->mainFrame()->document()->settings();
+            bool shouldCreateSolidColorScrollbar = settings->useSolidColorScrollbars() && settings->usesOverlayScrollbars();

[jamesr, 2013/09/03 23:06:19]

why are you checking usesSolidColor... *and* usesOverlay?  When would
usesSolidColor..() be true but not usesOverlay..()?

[enne (OOO), 2013/09/03 23:47:33]

My thought was that Android would set both of these flags.  Are you suggesting
you'd prefer just checking solid color (and ASSERTing overlay, maybe)?

[wjmaclean, 2013/09/04 13:27:59]

I can confirm that Android does currently set both of these flags. That being
said, it's also reasonable that if the solid color scrollbar setting is true,
then overlay scrollbars should also be true, since the solid color scrollbars
don't do any drawing outside the thumb. So, we could check for
useSolidColorScrollbars() and assert usesOverlayScrollbars().

Let me know which is preferred.

[jamesr, 2013/09/04 20:41:17]

I think either would be fine - either say that one setting requires the other
and ASSERT() or only check the useSolidColorScrollbars() setting and assume the
embedder has set up the settings in a reasonable way.  Let's just pick one.

+
+            OwnPtr<WebScrollbarLayer> webScrollbarLayer;
+            if (shouldCreateSolidColorScrollbar)
+                webScrollbarLayer = createSolidColorScrollbarLayer(orientation, -1);
+            else
+                webScrollbarLayer = createScrollbarLayer(scrollbar);
+            addWebScrollbarLayer(scrollableArea, orientation, webScrollbarLayer.release());
+        }
 
         // Root layer non-overlay scrollbars should be marked opaque to disable
         // blending.
         bool isOpaqueScrollbar = !scrollbar->isOverlayScrollbar();
         if (!scrollbarGraphicsLayer->contentsOpaque())
             scrollbarGraphicsLayer->setContentsOpaque(isMainFrame && isOpaqueScrollbar);
         scrollbarLayer->layer()->setOpaque(scrollbarGraphicsLayer->contentsOpaque());
 
         setupScrollbarLayer(scrollbarGraphicsLayer, scrollbarLayer, scrollingWebLayerForScrollableArea(scrollableArea));
     } else
@@ skipping 522 matching lines @@
         stringBuilder.resize(stringBuilder.length() - 2);
     return stringBuilder.toString();
 }
 
 String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
 {
     return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
 }
 
 } // namespace WebCore