Add overscroll edge effect animations for Android.

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
new file mode 100644
index 0000000000000000000000000000000000000000..fb4e2b9e6ffe0e44b843e39edb1ed05b3f805115
--- /dev/null
+++ b/content/browser/android/overscroll_glow.cc
@@ -0,0 +1,256 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/android/overscroll_glow.h"
+
+#include "cc/layers/image_layer.h"
+#include "skia/ext/image_operations.h"
+#include "ui/gfx/android/java_bitmap.h"
+
+namespace content {
+
+namespace {

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Delete all "static"s inside here

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+
+static const float VEC_LENGTH_EPS_SQUARED = 1e-5f;
+
+static SkBitmap CreateBitmap(const char* resource, gfx::Size size) {
+  SkBitmap bitmap = gfx::CreateSkBitmapFromResource(resource);
+  if (bitmap.isNull())
+    return bitmap;
+  return skia::ImageOperations::Resize(bitmap,
+                                       skia::ImageOperations::RESIZE_GOOD,
+                                       size.width(), size.height());
+}
+
+static const SkBitmap& GetOverscrollEdgeBitmap() {
+  static SkBitmap edge = CreateBitmap("android:drawable/overscroll_edge",
+                                      gfx::Size(256, 12));
+  return edge;
+}
+
+static const SkBitmap& GetOverscrollGlowBitmap() {
+  static SkBitmap glow = CreateBitmap("android:drawable/overscroll_glow",
+                                      gfx::Size(128, 128));
+  return glow;
+}
+
+static scoped_refptr<cc::Layer> NewLayer(const SkBitmap& bitmap) {
+  scoped_refptr<cc::ImageLayer> layer = cc::ImageLayer::Create();
+  layer->SetContentsOpaque(false);
+  layer->SetBitmap(bitmap);
+  return layer;
+}
+
+static bool IsApproxZero(const gfx::Vector2dF& vector) {
+  return vector.LengthSquared() < VEC_LENGTH_EPS_SQUARED;
+}
+
+}
+
+scoped_ptr<OverscrollGlow> OverscrollGlow::Create() {
+  const SkBitmap& edge = GetOverscrollEdgeBitmap();
+  const SkBitmap& glow = GetOverscrollGlowBitmap();
+  if (edge.isNull() || glow.isNull())
+    return scoped_ptr<OverscrollGlow>();
+
+  return make_scoped_ptr(new OverscrollGlow(edge, glow));
+}
+
+OverscrollGlow::OverscrollGlow(const SkBitmap& edge, const SkBitmap& glow)
+  : horizontal_overscroll_enabled_(true) {
+  for (unsigned i = 0; i < EDGE_COUNT; ++i) {
+    edge_effects_[i]
+       = make_scoped_ptr(new EdgeEffect(NewLayer(edge), NewLayer(glow)));
+  }
+}
+
+OverscrollGlow::~OverscrollGlow() { }
+
+void OverscrollGlow::OnOverscrolled(base::TimeTicks current_time,
+                                    gfx::Vector2dF overscroll,
+                                    gfx::Vector2dF velocity) {
+  if (!horizontal_overscroll_enabled_) {
+    overscroll.set_x(0);
+    velocity.set_x(0);
+  }
+
+  if (IsApproxZero(overscroll)) {
+    Release(current_time);
+    return;
+  }
+
+  if (!IsApproxZero(velocity)) {
+    if (velocity.x() * old_velocity_.x() < 0)
+      Release(AXIS_X, current_time);
+    if (velocity.y() * old_velocity_.y() < 0)
+      Release(AXIS_Y, current_time);
+
+    Absorb(current_time, velocity, overscroll, old_overscroll_);
+  } else {
+    if (overscroll.x() * old_overscroll_.x() < 0 ||
+        std::abs(overscroll.x()) < std::abs(old_overscroll_.x()))
+      Release(AXIS_X, current_time);
+    if (overscroll.y() * old_overscroll_.y() < 0 ||
+        std::abs(overscroll.y()) < std::abs(old_overscroll_.y()))
+      Release(AXIS_Y, current_time);
+
+    // Ensure monotonic overscroll accumulation
+    gfx::Vector2dF overscroll_delta = overscroll - old_overscroll_;
+    if (overscroll_delta.x() * old_overscroll_.x() < 0)
+      overscroll_delta.set_x(0);
+    if (overscroll_delta.y() * old_overscroll_.y() < 0)
+      overscroll_delta.set_y(0);
+
+    Pull(current_time, overscroll_delta);
+  }
+
+  old_velocity_ = velocity;
+  old_overscroll_ = overscroll;
+}
+
+void OverscrollGlow::Release(base::TimeTicks current_time) {
+  for (unsigned i = 0; i < EDGE_COUNT; ++i) {
+    edge_effects_[i]->Release(current_time);
+  }
+  old_overscroll_ = gfx::Vector2dF();
+  old_velocity_ = gfx::Vector2dF();
+}
+
+void OverscrollGlow::Finish() {
+  for (unsigned i = 0; i < EDGE_COUNT; ++i) {
+    edge_effects_[i]->Finish();
+  }
+  old_overscroll_ = gfx::Vector2dF();
+  old_velocity_ = gfx::Vector2dF();
+}
+
+bool OverscrollGlow::Animate(base::TimeTicks current_time) {
+  if (!IsAnimating())
+    return false;
+
+  const gfx::SizeF sizes[EDGE_COUNT] = {
+    size_, gfx::SizeF(size_.height(), size_.width()),
+    size_, gfx::SizeF(size_.height(), size_.width())
+  };
+
+  bool active = false;
+  for (unsigned i = 0; i < EDGE_COUNT; ++i) {
+    if (edge_effects_[i]->Update(current_time))
+      edge_effects_[i]->Draw(parent_layer_, sizes[i],
+                             static_cast<EdgeEffect::Edge>(i));
+  }
+
+  return active;
+}
+
+bool OverscrollGlow::IsAnimating() const {
+  for (unsigned i = 0; i < EDGE_COUNT; ++i) {
+    if (!edge_effects_[i]->IsFinished())
+      return true;
+  }
+  return false;
+}
+
+void OverscrollGlow::set_horizontal_overscroll_enabled(bool enabled) {
+  horizontal_overscroll_enabled_ = enabled;
+}
+
+void OverscrollGlow::set_size(const gfx::SizeF& size) {
+  size_ = size;
+}
+
+void OverscrollGlow::set_parent_layer(scoped_refptr<cc::Layer> parent_layer) {
+  if (parent_layer == parent_layer_)
+    return;
+
+  Finish();
+
+  parent_layer_ = parent_layer;
+}
+
+
+void OverscrollGlow::Pull(base::TimeTicks current_time,
+                          const gfx::Vector2dF& overscroll_delta) {
+  using std::max;

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Please delete these using declarations or move them to the top of the file.

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+  using std::min;
+
+  if (IsApproxZero(overscroll_delta))
+    return;
+
+  gfx::Vector2dF overscroll_pull = gfx::ScaleVector2d(overscroll_delta,
+                                                      1.f / size_.width(),
+                                                      1.f / size_.height());
+  float edge_overscroll_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 (unsigned  i = 0; i < EDGE_COUNT; ++i) {

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Should be "size_t i"

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+    if (!edge_overscroll_pull[i])
+      continue;
+
+    EdgeEffect& edge_effect = *edge_effects_[i];
+    EdgeEffect& opposite_edge_effect = *GetOppositeEdge(i);
+    edge_effect.Pull(current_time, std::abs(edge_overscroll_pull[i]));
+    if (!opposite_edge_effect.IsFinished())
+      opposite_edge_effect.Release(current_time);
+  }
+}
+
+void OverscrollGlow::Absorb(base::TimeTicks current_time,
+                            const gfx::Vector2dF& velocity,
+                            const gfx::Vector2dF& overscroll,
+                            const gfx::Vector2dF& old_overscroll) {
+  using std::max;

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Delete these

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+  using std::min;
+
+  if (IsApproxZero(overscroll) || IsApproxZero(velocity))
+    return;
+
+  // Only trigger on initial overscroll at a non-zero velocity
+  const float overscroll_velocities[EDGE_COUNT] = {
+    old_overscroll.y() >= 0 && overscroll.y() < 0 ? min(velocity.y(), 0.f) : 0,
+    old_overscroll.x() >= 0 && overscroll.x() < 0 ? min(velocity.x(), 0.f) : 0,
+    old_overscroll.y() <= 0 && overscroll.y() > 0 ? max(velocity.y(), 0.f) : 0,
+    old_overscroll.x() <= 0 && overscroll.x() > 0 ? max(velocity.x(), 0.f) : 0
+  };
+
+  for (unsigned  i = 0; i < EDGE_COUNT; ++i) {

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Should be "size_t i"

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+    if (!overscroll_velocities[i])
+      continue;
+
+    EdgeEffect& edge_effect = *edge_effects_[i];

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

Please use pointers here, non-const references are discouraged

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+    EdgeEffect& opposite_edge_effect = *GetOppositeEdge(i);
+    edge_effect.Absorb(current_time, std::abs(overscroll_velocities[i]));
+    if (!opposite_edge_effect.IsFinished())
+      opposite_edge_effect.Release(current_time);
+  }
+}
+
+void OverscrollGlow::Release(Axis axis, base::TimeTicks current_time) {
+  switch (axis) {
+    case AXIS_Y:
+      edge_effects_[EdgeEffect::EDGE_LEFT]->Release(current_time);
+      edge_effects_[EdgeEffect::EDGE_RIGHT]->Release(current_time);
+      old_overscroll_.set_y(0);
+      old_velocity_.set_y(0);
+      break;
+    case AXIS_X:
+    default:

[aelias_OOO_until_Jul13, 2013/04/22 23:46:48]

This "default" is weird.  Please delete it entirely or put it in a separate
clause that does "NOTREACHED"

[jdduke (slow), 2013/04/23 16:02:13]

Done.

+      edge_effects_[EdgeEffect::EDGE_LEFT]->Release(current_time);
+      edge_effects_[EdgeEffect::EDGE_RIGHT]->Release(current_time);
+      old_overscroll_.set_x(0);
+      old_velocity_.set_x(0);
+    break;
+  };
+}
+
+EdgeEffect* OverscrollGlow::GetOppositeEdge(int edge_index) {
+  return edge_effects_[(edge_index + 2) % EDGE_COUNT].get();
+}
+
+}  // namespace content
+