[Android] Add a native pull-to-refresh overscroll effect

content/browser/android/overscroll_controller_android.h

+// Copyright 2014 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.
+
+#ifndef CONTENT_BROWSER_ANDROID_OVERSCROLL_CONTROLLER_ANDROID_H_
+#define CONTENT_BROWSER_ANDROID_OVERSCROLL_CONTROLLER_ANDROID_H_
+
+#include "base/time/time.h"
+#include "content/browser/android/overscroll_glow.h"
+#include "content/browser/android/overscroll_refresh.h"
+#include "content/common/input/input_event_ack_state.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "ui/gfx/geometry/vector2d_f.h"
+
+namespace blink {
+class WebGestureEvent;
+}
+
+namespace cc {
+class CompositorFrameMetadata;
+class Layer;
+}
+
+namespace ui {
+class WindowAndroidCompositor;
+}
+
+namespace content {
+
+struct DidOverscrollParams;
+
+// Glue class for handling all inputs into Android-specific overscroll effects,
+// both the passive overscroll glow and the active overscroll pull-to-refresh.
+// Note that all input coordinates (both for events and overscroll) are in DIPs.
+class OverscrollControllerAndroid : public OverscrollRefreshClient,
+                                    public WebContentsObserver {
+ public:
+  OverscrollControllerAndroid(WebContents* web_contents,
+                              ui::WindowAndroidCompositor* compositor,
+                              float dpi_scale);
+  virtual ~OverscrollControllerAndroid();
+
+  // Returns true if |event| is consumed by an overscroll effect, in which
+  // case it should cease propagation.
+  bool WillHandleGestureEvent(const blink::WebGestureEvent& event);
+
+  // To be called upon receipt of a gesture event ack.
+  void OnGestureEventAck(const blink::WebGestureEvent& event,
+                         InputEventAckState ack_result);
+
+  // To be called upon receipt of an overscroll event.
+  void OnOverscrolled(const DidOverscrollParams& overscroll_params);
+
+  // Returns true if the effect still needs animation ticks.
+  // Note: The effect will detach itself when no further animation is required.
+  bool Animate(base::TimeTicks current_time, cc::Layer* parent_layer);
+
+  // To be called whenever the content frame has been updated.
+  void OnFrameMetadataUpdated(const cc::CompositorFrameMetadata& metadata);
+
+  // Toggle activity of any overscroll effects. When disabled, events will be
+  // ignored until the controller is re-enabled.
+  void Enable();
+  void Disable();
+
+ private:
+  // WebContentsObserver implementation.
+  void DidNavigateMainFrame(const LoadCommittedDetails& details,
+                            const FrameNavigateParams& params) override;
+
+  // OverscrollRefreshClient implementation.
+  void TriggerRefresh() override;
+  bool IsStillRefreshing() const override;
+
+  void SetNeedsAnimate();
+
+  ui::WindowAndroidCompositor* compositor_;
+  const float dpi_scale_;
+
+  bool enabled_;
+
+  // TODO(jdduke): Factor out a common API from the two overscroll effects.
+  OverscrollGlow glow_effect_;
+  OverscrollRefresh refresh_effect_;
+  bool triggered_refresh_active_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverscrollControllerAndroid);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_OVERSCROLL_CONTROLLER_ANDROID_H_