Insert pinch zoom virtual viewport layers to graphics layer tree.

Source/WebKit/chromium/src/PinchViewports.cpp

Index: Source/WebKit/chromium/src/PinchViewports.cpp
diff --git a/Source/WebKit/chromium/src/PinchViewports.cpp b/Source/WebKit/chromium/src/PinchViewports.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..73855a27c4449fdb549cd8a003f58a50784e228b
--- /dev/null
+++ b/Source/WebKit/chromium/src/PinchViewports.cpp
@@ -0,0 +1,193 @@
+/*
+ * 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
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "WebKit/chromium/src/PinchViewports.h"
+
+#include "WebKit/chromium/src/WebSettingsImpl.h"
+#include "WebKit/chromium/src/WebViewImpl.h"
+#include "core/page/FrameView.h"
+#include "core/platform/graphics/FloatSize.h"
+#include "core/platform/graphics/GraphicsLayer.h"
+#include "core/rendering/RenderLayerCompositor.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebCompositorSupport.h"
+#include "public/platform/WebLayerTreeView.h"
+#include "public/platform/WebScrollbarLayer.h"
+
+using WebCore::GraphicsLayer;
+
+namespace WebKit {
+
+PassOwnPtr<PinchViewports> PinchViewports::create(WebViewImpl* owner)
+{
+    return adoptPtr(new PinchViewports(owner));
+}
+
+PinchViewports::PinchViewports(WebViewImpl* owner)
+    : m_owner(owner)
+    , m_innerViewportClipLayer(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_innerViewportClipLayer->setMasksToBounds(true);
+    m_innerViewportClipLayer->platformLayer()->setIsContainerForFixedPositionLayers(true);
+
+    m_innerViewportScrollLayer->platformLayer()->setScrollable(true);
+
+#ifndef NDEBUG
+    m_innerViewportClipLayer->setName("inner viewport clip layer");
+    m_pageScaleLayer->setName("page scale layer");
+    m_innerViewportScrollLayer->setName("inner viewport scroll layer");
+    m_overlayScrollbarHorizontal->setName("overlay scrollbar horizontal");
+    m_overlayScrollbarVertical->setName("overlay scrollbar vertical");
+#endif
+
+    m_innerViewportClipLayer->addChild(m_pageScaleLayer.get());
+    m_pageScaleLayer->addChild(m_innerViewportScrollLayer.get());
+    m_innerViewportClipLayer->addChild(m_overlayScrollbarHorizontal.get());
+    m_innerViewportClipLayer->addChild(m_overlayScrollbarVertical.get());
+
+    // Setup the inner viewport overlay scrollbars.
+    setupScrollbar(WebScrollbar::Horizontal);
+    setupScrollbar(WebScrollbar::Vertical);
+}
+
+PinchViewports::~PinchViewports() { }
+
+void PinchViewports::setViewportSize(const WebSize& newSize)
+{
+    ASSERT(m_innerViewportClipLayer);

[aelias_OOO_until_Jul13, 2013/06/18 19:52:28]

nit: no need for this assertion since you create it in constructor.

[wjmaclean, 2013/06/18 20:11:40]

Done.

+    m_innerViewportClipLayer->setSize(WebCore::FloatSize(newSize.width, newSize.height));
+
+    // 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):
+//
+// *innerViewportClipLayer (fixed pos container)
+//  +- *pageScaleLayer
+//  |   +- *innerViewportScrollLayer
+//  |       +-- overflowControlsHostLayer (root layer)
+//  |           +-- outerViewportClipLayer (fixed pos container) [frame clip layer in RenderLayerCompositor]
+//  |           |   +-- outerViewportScrollLayer [frame scroll layer in RenderLayerCompositor]
+//  |           |       +-- content layers ...
+//  |           +-- horizontal ScrollbarLayer (non-overlay)
+//  |           +-- verticalScrollbarLayer (non-overlay)
+//  |           +-- scroll corner (non-overlay)
+//  +- *horizontalScrollbarLayer (overlay)
+//  +- *verticalScrollbarLayer (overlay)
+//
+void PinchViewports::setOverflowControlsHostLayer(GraphicsLayer* layer)
+{
+    if (layer) {
+        ASSERT(!m_innerViewportScrollLayer->children().size());
+        m_innerViewportScrollLayer->addChild(layer);
+    } else {
+        m_innerViewportScrollLayer->removeAllChildren();
+        return;
+    }
+
+    WebCore::Page* page = m_owner->page();
+    // We only need to disable the existing (outer viewport) scrollbars
+    // if the existing ones are already overlay.
+    if (!page || !page->mainFrame()->view()->hasOverlayScrollbars())
+        return;
+
+    // Disable the existing outer-viewport scrollbars, since we don't need to
+    // display two sets of overlay scrollbars.
+    // FIXME: If we knew in advance before the overflowControlsHostLayer goes

[aelias_OOO_until_Jul13, 2013/06/18 19:52:28]

I don't entirely follow what this problem is; why can't you fix this as part of
this patch?

[wjmaclean, 2013/06/18 20:11:40]

We only ever find out (I think) that the old compositor has gone away when
WVI::setRootGraphicsLayer() is called with layer == 0, by which time it's too
late to call WVI::compositor() and retrieve the two scrollbar layers so we can
re-enable the drawing.

Now, it may not be an issue, as I suspect by this time they're destroyed
anyways, but I'd like to return the layers to their original state in case
they're reused at a later time.

Is there a notification *before* the existing rootGraphicsLayer/compositor go
away?

[aelias_OOO_until_Jul13, 2013/06/18 22:26:00]

I suggest removing the early return and doing:

scrollbar->setDrawsContent(!page->mainFrame()->view()->hasOverlayScrollbars());

then you set it to the right value on every attach, and don't have to do
anything on detach.

+    // away, we would re-enable the drawing of these scrollbars.
+    // FIXME: When scrollbar existence is no longer tied to scrollability, see
+    // issue crbug.com/247055, inhibit the creation of these scrollbars when they're not needed.

[aelias_OOO_until_Jul13, 2013/06/18 19:52:28]

Why should we ever inhibit their creation?  They may unexpectedly need to appear
at any time due to an impl-thread handled gesture.  I suggest deleting this
FIXME comment.

[wjmaclean, 2013/06/18 20:11:40]

Done.

+    if (GraphicsLayer* scrollbar = m_owner->compositor()->layerForHorizontalScrollbar())
+        scrollbar->setDrawsContent(false);
+    if (GraphicsLayer* scrollbar = m_owner->compositor()->layerForVerticalScrollbar())
+        scrollbar->setDrawsContent(false);
+}
+
+void PinchViewports::setupScrollbar(WebScrollbar::Orientation orientation)
+{
+    bool isHorizontal = orientation == WebScrollbar::Horizontal;
+    GraphicsLayer* scrollbarGraphicsLayer = isHorizontal ?
+        m_overlayScrollbarHorizontal.get() : m_overlayScrollbarVertical.get();
+
+    const int kOverlayScrollbarThickness = m_owner->settingsImpl()->pinchOverlayScrollbarThickness();
+
+    ASSERT(scrollbarGraphicsLayer);

[aelias_OOO_until_Jul13, 2013/06/18 19:52:28]

nit: also no need for this assert since it's created in the constructor.

[wjmaclean, 2013/06/18 20:11:40]

Done.

+
+    int xPosition = isHorizontal ? 0 : m_innerViewportClipLayer->size().width() - kOverlayScrollbarThickness;
+    int yPosition = isHorizontal ? m_innerViewportClipLayer->size().height() - kOverlayScrollbarThickness : 0;
+    int width = isHorizontal ? m_innerViewportClipLayer->size().width() - kOverlayScrollbarThickness : kOverlayScrollbarThickness;
+    int height = isHorizontal ? kOverlayScrollbarThickness : m_innerViewportClipLayer->size().height() - kOverlayScrollbarThickness;
+
+    scrollbarGraphicsLayer->setPosition(WebCore::IntPoint(xPosition, yPosition));
+    scrollbarGraphicsLayer->setSize(WebCore::IntSize(width, height));
+}
+
+void PinchViewports::registerViewportLayersWithTreeView(WebLayerTreeView* layerTreeView) const
+{
+    if (!layerTreeView)
+        return;
+
+    WebCore::RenderLayerCompositor* compositor = m_owner->compositor();
+    ASSERT(compositor);
+    layerTreeView->registerPinchViewportLayers(
+        m_innerViewportClipLayer->platformLayer(),
+        m_pageScaleLayer->platformLayer(),
+        m_innerViewportScrollLayer->platformLayer(),
+        compositor->scrollLayer()->platformLayer(),
+        m_overlayScrollbarHorizontal->platformLayer(),
+        m_overlayScrollbarVertical->platformLayer());
+}
+
+void PinchViewports::clearViewportLayersForTreeView(WebLayerTreeView* layerTreeView) const
+{
+    if (!layerTreeView)
+        return;
+
+    layerTreeView->clearPinchViewportLayers();
+}
+
+void PinchViewports::notifyAnimationStarted(const GraphicsLayer*, double time)
+{
+}
+
+void PinchViewports::paintContents(const GraphicsLayer*, WebCore::GraphicsContext&, WebCore::GraphicsLayerPaintingPhase, const WebCore::IntRect& inClip)
+{
+}
+
+} // namespace WebKit