[Android] Implementation of overscroll effect for Android L

content/browser/android/overscroll_glow.cc

Index: content/browser/android/overscroll_glow.cc
diff --git a/content/browser/android/overscroll_glow.cc b/content/browser/android/overscroll_glow.cc
index fb491f3ebaacfbd5b4364601e56e10de80b23dbb..18f9e98ca877d08f46a1161762ae98304f5024b8 100644
--- a/content/browser/android/overscroll_glow.cc
+++ b/content/browser/android/overscroll_glow.cc
@@ -4,13 +4,15 @@
 
 #include "content/browser/android/overscroll_glow.h"
 
-#include "base/debug/trace_event.h"
-#include "base/lazy_instance.h"
+#include "base/android/build_info.h"
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
 #include "base/threading/worker_pool.h"
-#include "cc/layers/image_layer.h"
+#include "cc/layers/layer.h"
 #include "content/browser/android/edge_effect.h"
-#include "skia/ext/image_operations.h"
-#include "ui/gfx/android/java_bitmap.h"
+#include "content/browser/android/edge_effect_l.h"
+#include "ui/gfx/screen.h"
 
 using std::max;
 using std::min;
@@ -20,56 +22,9 @@ namespace content {
 namespace {
 
 const float kEpsilon = 1e-3f;
-const int kScaledEdgeHeight = 12;
-const int kScaledGlowHeight = 64;
-const float kEdgeHeightAtMdpi = 12.f;
-const float kGlowHeightAtMdpi = 128.f;
-
-SkBitmap CreateSkBitmapFromAndroidResource(const char* name, gfx::Size size) {
-  base::android::ScopedJavaLocalRef<jobject> jobj =
-      gfx::CreateJavaBitmapFromAndroidResource(name, size);
-  if (jobj.is_null())
-    return SkBitmap();
-
-  SkBitmap bitmap = CreateSkBitmapFromJavaBitmap(gfx::JavaBitmap(jobj.obj()));
-  if (bitmap.isNull())
-    return bitmap;
-
-  return skia::ImageOperations::Resize(
-      bitmap, skia::ImageOperations::RESIZE_BOX, size.width(), size.height());
-}
-
-class OverscrollResources {
- public:
-  OverscrollResources() {
-    TRACE_EVENT0("browser", "OverscrollResources::Create");
-    edge_bitmap_ =
-        CreateSkBitmapFromAndroidResource("android:drawable/overscroll_edge",
-                                          gfx::Size(128, kScaledEdgeHeight));
-    glow_bitmap_ =
-        CreateSkBitmapFromAndroidResource("android:drawable/overscroll_glow",
-                                          gfx::Size(128, kScaledGlowHeight));
-  }
-
-  const SkBitmap& edge_bitmap() const { return edge_bitmap_; }
-  const SkBitmap& glow_bitmap() const { return glow_bitmap_; }
-
- private:
-  SkBitmap edge_bitmap_;
-  SkBitmap glow_bitmap_;
 
-  DISALLOW_COPY_AND_ASSIGN(OverscrollResources);
-};
-
-// Leaky to allow access from a worker thread.
-base::LazyInstance<OverscrollResources>::Leaky g_overscroll_resources =
-    LAZY_INSTANCE_INITIALIZER;
-
-scoped_refptr<cc::Layer> CreateImageLayer(const SkBitmap& bitmap) {
-  scoped_refptr<cc::ImageLayer> layer = cc::ImageLayer::Create();
-  layer->SetBitmap(bitmap);
-  return layer;
-}
+// The maximum Android build version prior to L release.
+const int kKitKatSDKVersion = 19;
 
 bool IsApproxZero(float value) {
   return std::abs(value) < kEpsilon;
@@ -83,20 +38,84 @@ gfx::Vector2dF ZeroSmallComponents(gfx::Vector2dF vector) {
   return vector;
 }
 
-// Force loading of any necessary resources.  This function is thread-safe.
-void EnsureResources() {
-  g_overscroll_resources.Get();
+gfx::Transform ComputeTransform(OverscrollGlow::Edge edge,
+                                const gfx::SizeF& window_size,
+                                float offset) {
+  // Transforms assume the edge layers are anchored to their *top center point*.
+  switch (edge) {
+    case OverscrollGlow::EDGE_TOP:
+      return gfx::Transform(1, 0, 0, 1, 0, offset);
+    case OverscrollGlow::EDGE_LEFT:
+      return gfx::Transform(0, 1, -1, 0,
+          -window_size.height() / 2.f + offset,
+          window_size.height() / 2.f);
+    case OverscrollGlow::EDGE_BOTTOM:
+      return gfx::Transform(-1, 0, 0, -1, 0, window_size.height() + offset);
+    case OverscrollGlow::EDGE_RIGHT:
+      return gfx::Transform(0, -1, 1, 0,
+          -window_size.height() / 2.f + window_size.width() + offset,
+          window_size.height() / 2.f);
+    default:
+      NOTREACHED() << "Invalid edge: " << edge;
+      return gfx::Transform();
+  };
 }
 
-} // namespace
+gfx::SizeF ComputeSize(OverscrollGlow::Edge edge,
+                       const gfx::SizeF& window_size) {
+  switch (edge) {
+    case OverscrollGlow::EDGE_TOP:
+    case OverscrollGlow::EDGE_BOTTOM:
+      return window_size;
+    case OverscrollGlow::EDGE_LEFT:
+    case OverscrollGlow::EDGE_RIGHT:
+      return gfx::SizeF(window_size.height(), window_size.width());
+    default:
+      NOTREACHED() << "Invalid edge: " << edge;
+      return gfx::SizeF();
+  };
+}
+
+bool UseEdgeEffectL() {
+  static bool use_edge_effect_l =
+      base::android::BuildInfo::GetInstance()->sdk_int() > kKitKatSDKVersion;
+  return use_edge_effect_l;
+}
+
+void EnsureResourcesNonBlocking() {
+  static bool s_resources_loaded = false;
+
+  if (s_resources_loaded)
+    return;
 
-scoped_ptr<OverscrollGlow> OverscrollGlow::Create(bool enabled) {
   // Don't block the main thread with effect resource loading during creation.
   // Effect instantiation is deferred until the effect overscrolls, in which
   // case the main thread may block until the resource has loaded.
-  if (enabled && g_overscroll_resources == NULL)
-    base::WorkerPool::PostTask(FROM_HERE, base::Bind(EnsureResources), true);
+  s_resources_loaded = true;
+  if (UseEdgeEffectL()) {
+    base::WorkerPool::PostTask(
+        FROM_HERE, base::Bind(EdgeEffectL::EnsureResources), true);
+  } else {
+    base::WorkerPool::PostTask(
+        FROM_HERE, base::Bind(EdgeEffect::EnsureResources), true);
+  }
+}
 
+scoped_ptr<EdgeEffectBase> CreateEdgeEffect(cc::Layer* root_layer,
+                                            float device_scale_factor) {
+  scoped_ptr<EdgeEffectBase> result;
+  if (UseEdgeEffectL())
+    result = EdgeEffectL::Create(root_layer);
+  else
+    result = EdgeEffect::Create(root_layer, device_scale_factor);
+  return result.Pass();
+}
+
+} // namespace
+
+scoped_ptr<OverscrollGlow> OverscrollGlow::Create(bool enabled) {
+  if (enabled)
+    EnsureResourcesNonBlocking();
   return make_scoped_ptr(new OverscrollGlow(enabled));
 }
 
@@ -117,7 +136,7 @@ void OverscrollGlow::Disable() {
   enabled_ = false;
   if (!enabled_ && initialized_) {
     Detach();
-    for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i)
+    for (size_t i = 0; i < EDGE_COUNT; ++i)
       edge_effects_[i]->Finish();
   }
 }
@@ -126,7 +145,8 @@ bool OverscrollGlow::OnOverscrolled(cc::Layer* overscrolling_layer,
                                     base::TimeTicks current_time,
                                     gfx::Vector2dF accumulated_overscroll,
                                     gfx::Vector2dF overscroll_delta,
-                                    gfx::Vector2dF velocity) {
+                                    gfx::Vector2dF velocity,
+                                    gfx::Vector2dF displacement) {
   DCHECK(overscrolling_layer);
 
   if (!enabled_)
@@ -165,7 +185,7 @@ bool OverscrollGlow::OnOverscrolled(cc::Layer* overscrolling_layer,
   if (!velocity.IsZero())
     Absorb(current_time, velocity, x_overscroll_started, y_overscroll_started);
   else
-    Pull(current_time, overscroll_delta);
+    Pull(current_time, overscroll_delta, displacement);
 
   UpdateLayerAttachment(overscrolling_layer);
   return NeedsAnimate();
@@ -177,14 +197,13 @@ bool OverscrollGlow::Animate(base::TimeTicks current_time) {
     return false;
   }
 
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i) {
+  for (size_t i = 0; i < EDGE_COUNT; ++i) {
     if (edge_effects_[i]->Update(current_time)) {
+      Edge edge = static_cast<Edge>(i);
       edge_effects_[i]->ApplyToLayers(
-          display_params_.size,
-          static_cast<EdgeEffect::Edge>(i),
-          kEdgeHeightAtMdpi * display_params_.device_scale_factor,
-          kGlowHeightAtMdpi * display_params_.device_scale_factor,
-          display_params_.edge_offsets[i]);
+          ComputeSize(edge, display_params_.size),
+          ComputeTransform(
+              edge, display_params_.size, display_params_.edge_offsets[i]));
     }
   }
 
@@ -203,7 +222,7 @@ void OverscrollGlow::UpdateDisplayParameters(const DisplayParameters& params) {
 bool OverscrollGlow::NeedsAnimate() const {
   if (!enabled_ || !initialized_)
     return false;
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i) {
+  for (size_t i = 0; i < EDGE_COUNT; ++i) {
     if (!edge_effects_[i]->IsFinished())
       return true;
   }
@@ -234,71 +253,75 @@ bool OverscrollGlow::InitializeIfNecessary() {
   if (initialized_)
     return true;
 
-  const SkBitmap& edge = g_overscroll_resources.Get().edge_bitmap();
-  const SkBitmap& glow = g_overscroll_resources.Get().glow_bitmap();
-  if (edge.isNull() || glow.isNull()) {
-    Disable();
-    return false;
-  }
-
   DCHECK(!root_layer_);
-  root_layer_ = cc::Layer::Create();
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i) {
-    scoped_refptr<cc::Layer> edge_layer = CreateImageLayer(edge);
-    scoped_refptr<cc::Layer> glow_layer = CreateImageLayer(glow);
-    root_layer_->AddChild(edge_layer);
-    root_layer_->AddChild(glow_layer);
-    edge_effects_[i] = make_scoped_ptr(new EdgeEffect(edge_layer, glow_layer));
+  scoped_refptr<cc::Layer> root_layer = cc::Layer::Create();
+  const float device_scale_factor =
+      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().device_scale_factor();
+  for (size_t i = 0; i < EDGE_COUNT; ++i) {
+    edge_effects_[i] = CreateEdgeEffect(root_layer.get(), device_scale_factor);
+    if (!edge_effects_[i])
+      Disable();
   }
+  root_layer_ = root_layer;
 
   initialized_ = true;
   return true;
 }
 
 void OverscrollGlow::Pull(base::TimeTicks current_time,
-                          gfx::Vector2dF overscroll_delta) {
+                          const gfx::Vector2dF& overscroll_delta,
+                          const gfx::Vector2dF& overscroll_location) {
   DCHECK(enabled_ && initialized_);
-  overscroll_delta = ZeroSmallComponents(overscroll_delta);
-  if (overscroll_delta.IsZero())
-    return;
+  DCHECK(!overscroll_delta.IsZero());
+  const float inv_width = 1.f / display_params_.size.width();
+  const float inv_height = 1.f / display_params_.size.height();
 
   gfx::Vector2dF overscroll_pull =
-      gfx::ScaleVector2d(overscroll_delta,
-                         1.f / display_params_.size.width(),
-                         1.f / display_params_.size.height());
-  float edge_overscroll_pull[EdgeEffect::EDGE_COUNT] = {
+      gfx::ScaleVector2d(overscroll_delta, inv_width, inv_height);
+  const float edge_pull[EDGE_COUNT] = {
       min(overscroll_pull.y(), 0.f),  // Top
       min(overscroll_pull.x(), 0.f),  // Left
       max(overscroll_pull.y(), 0.f),  // Bottom
       max(overscroll_pull.x(), 0.f)   // Right
   };
 
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i) {
-    if (!edge_overscroll_pull[i])
+  gfx::Vector2dF displacement =
+      gfx::ScaleVector2d(overscroll_location, inv_width, inv_height);
+  displacement.set_x(max(0.f, min(1.f, displacement.x())));
+  displacement.set_y(max(0.f, min(1.f, displacement.y())));
+  const float edge_displacement[EDGE_COUNT] = {
+    1.f - displacement.x(),  // Top
+    displacement.y(),        // Left
+    displacement.x(),        // Bottom
+    1.f - displacement.y()   // Right
+  };
+
+  for (size_t i = 0; i < EDGE_COUNT; ++i) {
+    if (!edge_pull[i])
       continue;
 
-    edge_effects_[i]->Pull(current_time, std::abs(edge_overscroll_pull[i]));
+    edge_effects_[i]->Pull(
+        current_time, std::abs(edge_pull[i]), edge_displacement[i]);
     GetOppositeEdge(i)->Release(current_time);
   }
 }
 
 void OverscrollGlow::Absorb(base::TimeTicks current_time,
-                            gfx::Vector2dF velocity,
+                            const gfx::Vector2dF& velocity,
                             bool x_overscroll_started,
                             bool y_overscroll_started) {
   DCHECK(enabled_ && initialized_);
-  if (velocity.IsZero())
-    return;
+  DCHECK(!velocity.IsZero());
 
   // Only trigger on initial overscroll at a non-zero velocity
-  const float overscroll_velocities[EdgeEffect::EDGE_COUNT] = {
+  const float overscroll_velocities[EDGE_COUNT] = {
       y_overscroll_started ? min(velocity.y(), 0.f) : 0,  // Top
       x_overscroll_started ? min(velocity.x(), 0.f) : 0,  // Left
       y_overscroll_started ? max(velocity.y(), 0.f) : 0,  // Bottom
       x_overscroll_started ? max(velocity.x(), 0.f) : 0   // Right
   };
 
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i) {
+  for (size_t i = 0; i < EDGE_COUNT; ++i) {
     if (!overscroll_velocities[i])
       continue;
 
@@ -309,7 +332,7 @@ void OverscrollGlow::Absorb(base::TimeTicks current_time,
 
 void OverscrollGlow::Release(base::TimeTicks current_time) {
   DCHECK(initialized_);
-  for (size_t i = 0; i < EdgeEffect::EDGE_COUNT; ++i)
+  for (size_t i = 0; i < EDGE_COUNT; ++i)
     edge_effects_[i]->Release(current_time);
 }
 
@@ -317,23 +340,22 @@ void OverscrollGlow::ReleaseAxis(Axis axis, base::TimeTicks current_time) {
   DCHECK(initialized_);
   switch (axis) {
     case AXIS_X:
-      edge_effects_[EdgeEffect::EDGE_LEFT]->Release(current_time);
-      edge_effects_[EdgeEffect::EDGE_RIGHT]->Release(current_time);
+      edge_effects_[EDGE_LEFT]->Release(current_time);
+      edge_effects_[EDGE_RIGHT]->Release(current_time);
       break;
     case AXIS_Y:
-      edge_effects_[EdgeEffect::EDGE_TOP]->Release(current_time);
-      edge_effects_[EdgeEffect::EDGE_BOTTOM]->Release(current_time);
+      edge_effects_[EDGE_TOP]->Release(current_time);
+      edge_effects_[EDGE_BOTTOM]->Release(current_time);
       break;
   };
 }
 
-EdgeEffect* OverscrollGlow::GetOppositeEdge(int edge_index) {
+EdgeEffectBase* OverscrollGlow::GetOppositeEdge(int edge_index) {
   DCHECK(initialized_);
-  return edge_effects_[(edge_index + 2) % EdgeEffect::EDGE_COUNT].get();
+  return edge_effects_[(edge_index + 2) % EDGE_COUNT].get();
 }
 
-OverscrollGlow::DisplayParameters::DisplayParameters()
-    : device_scale_factor(1) {
+OverscrollGlow::DisplayParameters::DisplayParameters() {
   edge_offsets[0] = edge_offsets[1] = edge_offsets[2] = edge_offsets[3] = 0.f;
 }