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
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ScrollElasticityController_h
#define ScrollElasticityController_h
#if USE(RUBBER_BANDING)
#include "platform/PlatformExport.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/geometry/FloatSize.h"
#include "platform/scroll/ScrollTypes.h"
#include "wtf/Noncopyable.h"
namespace WebCore {
class PlatformWheelEvent;
class ScrollElasticityControllerClient {
protected:
virtual ~ScrollElasticityControllerClient() { }
public:
virtual bool allowsHorizontalStretching() = 0;
virtual bool allowsVerticalStretching() = 0;
// The amount that the view is stretched past the normal allowable bounds.
// The "overhang" amount.
virtual IntSize stretchAmount() = 0;
virtual bool pinnedInDirection(const FloatSize&) = 0;
virtual bool canScrollHorizontally() = 0;
virtual bool canScrollVertically() = 0;
// Return the absolute scroll position, not relative to the scroll origin.
virtual WebCore::IntPoint absoluteScrollPosition() = 0;
virtual void immediateScrollBy(const FloatSize&) = 0;
virtual void immediateScrollByWithoutContentEdgeConstraints(const FloatSize&) = 0;
virtual void startSnapRubberbandTimer() = 0;
virtual void stopSnapRubberbandTimer() = 0;
// If the current scroll position is within the overhang area, this function will cause
// the page to scroll to the nearest boundary point.
virtual void adjustScrollPositionToBoundsIfNecessary() = 0;
};
class PLATFORM_EXPORT ScrollElasticityController {
WTF_MAKE_NONCOPYABLE(ScrollElasticityController);
public:
explicit ScrollElasticityController(ScrollElasticityControllerClient*);
// This method is responsible for both scrolling and rubber-banding.
//
// Events are passed by IPC from the embedder. Events on Mac are grouped
// into "gestures". If this method returns 'true', then this object has
// handled the event. It expects the embedder to continue to forward events
// from the gesture.
//
// This method makes the assumption that there is only 1 input device being
// used at a time. If the user simultaneously uses multiple input devices,
// Cocoa does not correctly pass all the gestureBegin/End events. The state
// of this class is guaranteed to become eventually consistent, once the
// user stops using multiple input devices.
bool handleWheelEvent(const PlatformWheelEvent&);
void snapRubberBandTimerFired();
bool isRubberBandInProgress() const;
private:
void stopSnapRubberbandTimer();
void snapRubberBand();
// This method determines whether a given event should be handled. The
// logic for control events of gestures (PhaseBegan, PhaseEnded) is handled
// elsewhere.
//
// This class handles almost all wheel events. All of the following
// conditions must be met for this class to ignore an event:
// + No previous events in this gesture have caused any scrolling or rubber
// banding.
// + The event contains a horizontal component.
// + The client's view is pinned in the horizontal direction of the event.
// + The wheel event disallows rubber banding in the horizontal direction
// of the event.
bool shouldHandleEvent(const PlatformWheelEvent&);
ScrollElasticityControllerClient* m_client;
// There is an active scroll gesture event. This parameter only gets set to
// false after the rubber band has been snapped, and before a new gesture
// has begun. A careful audit of the code may deprecate the need for this
// parameter.
bool m_inScrollGesture;
// At least one event in the current gesture has been consumed and has
// caused the view to scroll or rubber band. All future events in this
// gesture will be consumed and overscrolls will cause rubberbanding.
bool m_hasScrolled;
bool m_momentumScrollInProgress;
bool m_ignoreMomentumScrolls;
CFTimeInterval m_lastMomentumScrollTimestamp;
FloatSize m_overflowScrollDelta;
FloatSize m_stretchScrollForce;
FloatSize m_momentumVelocity;
// Rubber band state.
CFTimeInterval m_startTime;
FloatSize m_startStretch;
FloatPoint m_origOrigin;
FloatSize m_origVelocity;
bool m_snapRubberbandTimerIsActive;
};
} // namespace WebCore
#endif // USE(RUBBER_BANDING)
#endif // ScrollElasticityController_h
|
