| // Copyright (c) 2012 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_RENDERER_HOST_OVERSCROLL_CONTROLLER_H_ |
| #define CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_H_ |
| |
| #include "base/basictypes.h" |
| #include "base/compiler_specific.h" |
| #include "third_party/WebKit/public/web/WebInputEvent.h" |
| |
| namespace ui { |
| struct LatencyInfo; |
| } |
| |
| namespace content { |
| |
| class MockRenderWidgetHost; |
| class OverscrollControllerDelegate; |
| |
| // Indicates the direction that the scroll is heading in relative to the screen, |
| // with the top being NORTH. |
| enum OverscrollMode { |
| OVERSCROLL_NONE, |
| OVERSCROLL_NORTH, |
| OVERSCROLL_SOUTH, |
| OVERSCROLL_WEST, |
| OVERSCROLL_EAST, |
| OVERSCROLL_COUNT |
| }; |
| |
| // When a page is scrolled beyond the scrollable region, it will trigger an |
| // overscroll gesture. This controller receives the events that are dispatched |
| // to the renderer, and the ACKs of events, and updates the overscroll gesture |
| // status accordingly. |
| class OverscrollController { |
| public: |
| OverscrollController(); |
| virtual ~OverscrollController(); |
| |
| // The result of |DispatchEvent()|, indicating either how the event was |
| // handled, or how it should be handled by the caller. |
| enum Disposition { |
| CONSUMED, |
| SHOULD_FORWARD_TO_RENDERER, |
| SHOULD_FORWARD_TO_GESTURE_FILTER |
| }; |
| // This must be called when dispatching any event from the |
| // RenderWidgetHostView so that the state of the overscroll gesture can be |
| // updated properly. |
| Disposition DispatchEvent(const blink::WebInputEvent& event, |
| const ui::LatencyInfo& latency_info); |
| |
| // This must be called when the ACK for any event comes in. This updates the |
| // overscroll gesture status as appropriate. |
| void ReceivedEventACK(const blink::WebInputEvent& event, bool processed); |
| |
| // This must be called when a gesture event is filtered out and not sent to |
| // the renderer. |
| void DiscardingGestureEvent(const blink::WebGestureEvent& event); |
| |
| OverscrollMode overscroll_mode() const { return overscroll_mode_; } |
| |
| void set_delegate(OverscrollControllerDelegate* delegate) { |
| delegate_ = delegate; |
| } |
| |
| // Resets internal states. |
| void Reset(); |
| |
| // Cancels any in-progress overscroll (and calls OnOverscrollModeChange on the |
| // delegate if necessary), and resets internal states. |
| void Cancel(); |
| |
| private: |
| friend class MockRenderWidgetHost; |
| |
| // Different scrolling states. |
| enum ScrollState { |
| STATE_UNKNOWN, |
| STATE_PENDING, |
| STATE_CONTENT_SCROLLING, |
| STATE_OVERSCROLLING, |
| }; |
| |
| // Returns true if the event indicates that the in-progress overscroll gesture |
| // can now be completed. |
| bool DispatchEventCompletesAction( |
| const blink::WebInputEvent& event) const; |
| |
| // Returns true to indicate that dispatching the event should reset the |
| // overscroll gesture status. |
| bool DispatchEventResetsState(const blink::WebInputEvent& event) const; |
| |
| // Processes an event to update the internal state for overscroll. Returns |
| // true if the state is updated, false otherwise. |
| bool ProcessEventForOverscroll(const blink::WebInputEvent& event); |
| |
| // Processes horizontal overscroll. This can update both the overscroll mode |
| // and the over scroll amount (i.e. |overscroll_mode_|, |overscroll_delta_x_| |
| // and |overscroll_delta_y_|). |
| void ProcessOverscroll(float delta_x, |
| float delta_y, |
| blink::WebInputEvent::Type event_type); |
| |
| // Completes the desired action from the current gesture. |
| void CompleteAction(); |
| |
| // Sets the overscroll mode (and triggers callback in the delegate when |
| // appropriate). |
| void SetOverscrollMode(OverscrollMode new_mode); |
| |
| // The current state of overscroll gesture. |
| OverscrollMode overscroll_mode_; |
| |
| // Used to keep track of the scrolling state. |
| // If scrolling starts, and some scroll events are consumed at the beginning |
| // of the scroll (i.e. some content on the web-page was scrolled), then do not |
| // process any of the subsequent scroll events for generating overscroll |
| // gestures. |
| ScrollState scroll_state_; |
| |
| // The amount of overscroll in progress. These values are invalid when |
| // |overscroll_mode_| is set to OVERSCROLL_NONE. |
| float overscroll_delta_x_; |
| float overscroll_delta_y_; |
| |
| // The delegate that receives the overscroll updates. The delegate is not |
| // owned by this controller. |
| OverscrollControllerDelegate* delegate_; |
| |
| DISALLOW_COPY_AND_ASSIGN(OverscrollController); |
| }; |
| |
| } // namespace content |
| |
| #endif // CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_H_ |