Add overscroll edge effect animations for Android.

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index e247e3b7b9dcda1813adbbe7c0c1a4f9d9cc33a5..10266d13b1dfaae16be29aeb54535602af349c94 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -7,6 +7,7 @@
 #include <android/bitmap.h>
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
@@ -15,6 +16,7 @@
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "content/browser/android/content_view_core_impl.h"
+#include "content/browser/android/overscroll_glow.h"
 #include "content/browser/gpu/gpu_surface_tracker.h"
 #include "content/browser/renderer_host/compositor_impl_android.h"
 #include "content/browser/renderer_host/image_transport_factory_android.h"
@@ -23,6 +25,7 @@
 #include "content/common/gpu/client/gl_helper.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/view_messages.h"
+#include "content/public/common/content_switches.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/Platform.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebExternalTextureLayer.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebSize.h"
@@ -39,6 +42,8 @@ namespace content {
 
 namespace {
 
+static const int kDesiredAnimationIntervalInMs = 16;
+
 void InsertSyncPointAndAckForGpu(
     int gpu_host_id, int route_id, const std::string& return_mailbox) {
   uint32 sync_point =
@@ -73,7 +78,7 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
     RenderWidgetHostImpl* widget_host,
     ContentViewCoreImpl* content_view_core)
     : host_(widget_host),
-      is_layer_attached_(true),
+      are_layers_attached_(true),
       content_view_core_(NULL),
       ime_adapter_android_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
       cached_background_color_(SK_ColorWHITE),
@@ -89,6 +94,11 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
   layer_->SetContentsOpaque(true);
   layer_->SetIsDrawable(true);
 
+  if (CommandLine::ForCurrentProcess()->
+          HasSwitch(switches::kEnableOverscrollEdgeEffect)) {
+    overscroll_effect_ = OverscrollGlow::Create();
+  }
+
   host_->SetView(this);
   SetContentViewCore(content_view_core);
 }
@@ -289,28 +299,26 @@ bool RenderWidgetHostViewAndroid::IsSurfaceAvailableForCopy() const {
 }
 
 void RenderWidgetHostViewAndroid::Show() {
-  if (is_layer_attached_)
+  if (are_layers_attached_)
     return;
 
-  is_layer_attached_ = true;
-  if (content_view_core_)
-    content_view_core_->AttachLayer(layer_);
+  are_layers_attached_ = true;
+  AttachLayers();
 }
 
 void RenderWidgetHostViewAndroid::Hide() {
-  if (!is_layer_attached_)
+  if (!are_layers_attached_)
     return;
 
-  is_layer_attached_ = false;
-  if (content_view_core_)
-    content_view_core_->RemoveLayer(layer_);
+  are_layers_attached_ = false;
+  RemoveLayers();
 }
 
 bool RenderWidgetHostViewAndroid::IsShowing() {
   // ContentViewCoreImpl represents the native side of the Java
   // ContentViewCore.  It being NULL means that it is not attached
   // to the View system yet, so we treat this RWHVA as hidden.
-  return is_layer_attached_ && content_view_core_;
+  return are_layers_attached_ && content_view_core_;
 }
 
 gfx::Rect RenderWidgetHostViewAndroid::GetViewBounds() const {
@@ -413,10 +421,10 @@ void RenderWidgetHostViewAndroid::RenderViewGone(
 }
 
 void RenderWidgetHostViewAndroid::Destroy() {
-  if (content_view_core_) {
-    content_view_core_->RemoveLayer(layer_);
-    content_view_core_ = NULL;
-  }
+  RemoveLayers();
+  content_view_core_ = NULL;
+
+  overscroll_effect_.reset();
 
   // The RenderWidgetHost's destruction led here, so don't call it.
   host_ = NULL;
@@ -547,6 +555,17 @@ void RenderWidgetHostViewAndroid::OnSwapCompositorFrame(
                  content_size,
                  callback);
 
+  if (overscroll_effect_) {
+    // Disable left/right edge effects when fully zoomed out.
+    const cc::CompositorFrameMetadata& metadata = frame->metadata;
+    bool horizontal_scrolling_possible =
+        metadata.page_scale_factor != metadata.min_page_scale_factor &&
+        metadata.root_layer_size.width() != metadata.viewport_size.width();
+
+    overscroll_effect_->set_horizontal_overscroll_enabled(
+        horizontal_scrolling_possible);
+    overscroll_effect_->set_size(content_size);
+  }
 }
 
 void RenderWidgetHostViewAndroid::AcceleratedSurfaceBuffersSwapped(
@@ -618,6 +637,42 @@ void RenderWidgetHostViewAndroid::BuffersSwapped(
   ack_callback.Run();
 }
 
+void RenderWidgetHostViewAndroid::AttachLayers() {
+  if (!content_view_core_)
+    return;
+
+  content_view_core_->AttachLayer(layer_);
+
+  if (overscroll_effect_)
+    overscroll_effect_->set_parent_layer(content_view_core_->GetLayer());
+}
+
+void RenderWidgetHostViewAndroid::RemoveLayers() {
+  if (!content_view_core_)
+    return;
+
+  if (overscroll_effect_)
+    overscroll_effect_->set_parent_layer(NULL);
+
+  content_view_core_->RemoveLayer(layer_);
+}
+
+void RenderWidgetHostViewAndroid::AnimationCallback() {
+  if (overscroll_effect_ && overscroll_effect_->Animate(base::TimeTicks::Now()))
+    ScheduleAnimation();
+}
+
+void RenderWidgetHostViewAndroid::ScheduleAnimation() {
+  if (animation_timer_.IsRunning() || !overscroll_effect_)
+    return;
+
+  const base::TimeDelta animationInterval
+      = base::TimeDelta::FromMilliseconds(kDesiredAnimationIntervalInMs);
+
+  animation_timer_.Start(FROM_HERE, animationInterval, this,

[mkosiba (inactive), 2013/04/22 16:24:53]

I'm not familiar with how animations work, so I apologize if it's a silly
question.
How is this synchronized with VSync? If the animation update tick isn't in sync
with the how CC produces frames won't the animation be janky?

[jdduke (slow), 2013/04/22 17:18:16]

It's not synchronized :) The timer hack was really only intended to get things
working quickly.  In practice, it works fairly well, but only because the effect
lacks any kind of sharp contrast with the background.

I've been waiting on https://chromiumcodereview.appspot.com/11959036 for vsync
hooks, which just landed. That will be the next addition.

+                         &RenderWidgetHostViewAndroid::AnimationCallback);
+}
+
 void RenderWidgetHostViewAndroid::AcceleratedSurfacePostSubBuffer(
     const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
     int gpu_host_id) {
@@ -755,14 +810,25 @@ SkColor RenderWidgetHostViewAndroid::GetCachedBackgroundColor() const {
   return cached_background_color_;
 }
 
+void RenderWidgetHostViewAndroid::OnOverscrolled(
+    const gfx::Vector2dF& accumulated_overscroll,
+    const gfx::Vector2dF& current_fling_velocity) {
+  if (overscroll_effect_) {
+    overscroll_effect_->OnOverscrolled(base::TimeTicks::Now(),
+                                       accumulated_overscroll,
+                                       current_fling_velocity);
+    ScheduleAnimation();
+  }
+}
+
 void RenderWidgetHostViewAndroid::SetContentViewCore(
     ContentViewCoreImpl* content_view_core) {
-  if (content_view_core_ && is_layer_attached_)
-    content_view_core_->RemoveLayer(layer_);
+  if (are_layers_attached_)
+    RemoveLayers();
 
   content_view_core_ = content_view_core;
-  if (content_view_core_ && is_layer_attached_)
-    content_view_core_->AttachLayer(layer_);
+  if (are_layers_attached_)
+    AttachLayers();
 }
 
 void RenderWidgetHostViewAndroid::HasTouchEventHandlers(