1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
// 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/Source/WebKit/chromium/public/WebInputEvent.h"
namespace ui {
struct LatencyInfo;
}
namespace content {
class MockRenderWidgetHost;
class OverscrollControllerDelegate;
class RenderWidgetHostImpl;
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:
// Creates an overscroll controller for the specified RenderWidgetHost.
// The RenderWidgetHost owns this overscroll controller.
explicit OverscrollController(RenderWidgetHostImpl* widget_host);
virtual ~OverscrollController();
// This must be called when dispatching any event from the
// RenderWidgetHostView so that the state of the overscroll gesture can be
// updated properly.
// Returns true if the event should be dispatched, false otherwise.
bool WillDispatchEvent(const WebKit::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 WebKit::WebInputEvent& event, bool processed);
OverscrollMode overscroll_mode() const { return overscroll_mode_; }
void set_delegate(OverscrollControllerDelegate* delegate) {
delegate_ = delegate;
}
// Resets internal states.
void Reset();
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 WebKit::WebInputEvent& event) const;
// Returns true to indicate that dispatching the event should reset the
// overscroll gesture status.
bool DispatchEventResetsState(const WebKit::WebInputEvent& event) const;
// Processes an event and updates internal state for overscroll.
void ProcessEventForOverscroll(const WebKit::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);
// 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);
// Returns whether the input event should be forwarded to the
// GestureEventFilter.
bool ShouldForwardToGestureFilter(const WebKit::WebInputEvent& event) const;
// The RenderWidgetHost that owns this overscroll controller.
RenderWidgetHostImpl* render_widget_host_;
// 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_
|
