summaryrefslogtreecommitdiffstats
path: root/widget/cocoa/SwipeTracker.mm
blob: 51169171a4a3209f1ec0c54c2a6e72dd1848af36 (plain)
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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "SwipeTracker.h"

#include "InputData.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/TouchEvents.h"
#include "nsAlgorithm.h"
#include "nsChildView.h"
#include "UnitTransforms.h"

// These values were tweaked to make the physics feel similar to the native swipe.
static const double kSpringForce = 250.0;
static const double kVelocityTwitchTolerance = 0.0000001;
static const double kWholePagePixelSize = 1000.0;
static const double kRubberBandResistanceFactor = 4.0;
static const double kSwipeSuccessThreshold = 0.25;
static const double kSwipeSuccessVelocityContribution = 0.3;

namespace mozilla {

static already_AddRefed<nsRefreshDriver>
GetRefreshDriver(nsIWidget& aWidget)
{
  nsIWidgetListener* widgetListener = aWidget.GetWidgetListener();
  nsIPresShell* presShell = widgetListener ? widgetListener->GetPresShell() : nullptr;
  nsPresContext* presContext = presShell ? presShell->GetPresContext() : nullptr;
  RefPtr<nsRefreshDriver> refreshDriver = presContext ? presContext->RefreshDriver() : nullptr;
  return refreshDriver.forget();
}

SwipeTracker::SwipeTracker(nsChildView& aWidget,
                           const PanGestureInput& aSwipeStartEvent,
                           uint32_t aAllowedDirections,
                           uint32_t aSwipeDirection)
  : mWidget(aWidget)
  , mRefreshDriver(GetRefreshDriver(mWidget))
  , mAxis(0.0, 0.0, 0.0, kSpringForce, 1.0)
  , mEventPosition(RoundedToInt(ViewAs<LayoutDevicePixel>(aSwipeStartEvent.mPanStartPoint,
                                  PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent)))
  , mLastEventTimeStamp(aSwipeStartEvent.mTimeStamp)
  , mAllowedDirections(aAllowedDirections)
  , mSwipeDirection(aSwipeDirection)
  , mGestureAmount(0.0)
  , mCurrentVelocity(0.0)
  , mEventsAreControllingSwipe(true)
  , mEventsHaveStartedNewGesture(false)
  , mRegisteredWithRefreshDriver(false)
{
  SendSwipeEvent(eSwipeGestureStart, 0, 0.0);
  ProcessEvent(aSwipeStartEvent);
}

void
SwipeTracker::Destroy()
{
  UnregisterFromRefreshDriver();
}

SwipeTracker::~SwipeTracker()
{
  MOZ_ASSERT(!mRegisteredWithRefreshDriver, "Destroy needs to be called before deallocating");
}

double
SwipeTracker::SwipeSuccessTargetValue() const
{
  return (mSwipeDirection == nsIDOMSimpleGestureEvent::DIRECTION_RIGHT) ? -1.0 : 1.0;
}

double
SwipeTracker::ClampToAllowedRange(double aGestureAmount) const
{
  // gestureAmount needs to stay between -1 and 0 when swiping right and
  // between 0 and 1 when swiping left.
  double min = (mSwipeDirection == nsIDOMSimpleGestureEvent::DIRECTION_RIGHT) ? -1.0 : 0.0;
  double max = (mSwipeDirection == nsIDOMSimpleGestureEvent::DIRECTION_LEFT) ? 1.0 : 0.0;
  return clamped(aGestureAmount, min, max);
}

bool
SwipeTracker::ComputeSwipeSuccess() const
{
  double targetValue = SwipeSuccessTargetValue();

  // If the fingers were moving away from the target direction when they were
  // lifted from the touchpad, abort the swipe.
  if (mCurrentVelocity * targetValue < -kVelocityTwitchTolerance) {
    return false;
  }

  return (mGestureAmount * targetValue +
          mCurrentVelocity * targetValue * kSwipeSuccessVelocityContribution) >= kSwipeSuccessThreshold;
}

nsEventStatus
SwipeTracker::ProcessEvent(const PanGestureInput& aEvent)
{
  // If the fingers have already been lifted, don't process this event for swiping.
  if (!mEventsAreControllingSwipe) {
    // Return nsEventStatus_eConsumeNoDefault for events from the swipe gesture
    // and nsEventStatus_eIgnore for events of subsequent scroll gestures.
    if (aEvent.mType == PanGestureInput::PANGESTURE_MAYSTART ||
        aEvent.mType == PanGestureInput::PANGESTURE_START) {
      mEventsHaveStartedNewGesture = true;
    }
    return mEventsHaveStartedNewGesture ? nsEventStatus_eIgnore : nsEventStatus_eConsumeNoDefault;
  }

  double delta = -aEvent.mPanDisplacement.x / mWidget.BackingScaleFactor() / kWholePagePixelSize;
  if (!SwipingInAllowedDirection()) {
    delta /= kRubberBandResistanceFactor;
  }
  mGestureAmount = ClampToAllowedRange(mGestureAmount + delta);
  SendSwipeEvent(eSwipeGestureUpdate, 0, mGestureAmount);

  if (aEvent.mType != PanGestureInput::PANGESTURE_END) {
    double elapsedSeconds = std::max(0.008, (aEvent.mTimeStamp - mLastEventTimeStamp).ToSeconds());
    mCurrentVelocity = delta / elapsedSeconds;
    mLastEventTimeStamp = aEvent.mTimeStamp;
  } else {
    mEventsAreControllingSwipe = false;
    bool didSwipeSucceed = SwipingInAllowedDirection() && ComputeSwipeSuccess();
    double targetValue = 0.0;
    if (didSwipeSucceed) {
      SendSwipeEvent(eSwipeGesture, mSwipeDirection, 0.0);
      targetValue = SwipeSuccessTargetValue();
    }
    StartAnimating(targetValue);
  }

  return nsEventStatus_eConsumeNoDefault;
}

void
SwipeTracker::StartAnimating(double aTargetValue)
{
  mAxis.SetPosition(mGestureAmount);
  mAxis.SetDestination(aTargetValue);
  mAxis.SetVelocity(mCurrentVelocity);

  mLastAnimationFrameTime = TimeStamp::Now();

  // Add ourselves as a refresh driver observer. The refresh driver
  // will call WillRefresh for each animation frame until we
  // unregister ourselves.
  MOZ_ASSERT(!mRegisteredWithRefreshDriver);
  if (mRefreshDriver) {
    mRefreshDriver->AddRefreshObserver(this, Flush_Style);
    mRegisteredWithRefreshDriver = true;
  }
}

void
SwipeTracker::WillRefresh(mozilla::TimeStamp aTime)
{
  TimeStamp now = TimeStamp::Now();
  mAxis.Simulate(now - mLastAnimationFrameTime);
  mLastAnimationFrameTime = now;

  bool isFinished = mAxis.IsFinished(1.0 / kWholePagePixelSize);
  mGestureAmount = (isFinished ? mAxis.GetDestination() : mAxis.GetPosition());
  SendSwipeEvent(eSwipeGestureUpdate, 0, mGestureAmount);

  if (isFinished) {
    UnregisterFromRefreshDriver();
    SwipeFinished();
  }
}

void
SwipeTracker::CancelSwipe()
{
  SendSwipeEvent(eSwipeGestureEnd, 0, 0.0);
}

void SwipeTracker::SwipeFinished()
{
  SendSwipeEvent(eSwipeGestureEnd, 0, 0.0);
  mWidget.SwipeFinished();
}

void
SwipeTracker::UnregisterFromRefreshDriver()
{
  if (mRegisteredWithRefreshDriver) {
    MOZ_ASSERT(mRefreshDriver, "How were we able to register, then?");
    mRefreshDriver->RemoveRefreshObserver(this, Flush_Style);
  }
  mRegisteredWithRefreshDriver = false;
}

/* static */ WidgetSimpleGestureEvent
SwipeTracker::CreateSwipeGestureEvent(EventMessage aMsg, nsIWidget* aWidget,
                                      const LayoutDeviceIntPoint& aPosition)
{
  WidgetSimpleGestureEvent geckoEvent(true, aMsg, aWidget);
  geckoEvent.mModifiers = 0;
  geckoEvent.mTimeStamp = TimeStamp::Now();
  geckoEvent.mRefPoint = aPosition;
  geckoEvent.buttons = 0;
  return geckoEvent;
}

bool
SwipeTracker::SendSwipeEvent(EventMessage aMsg, uint32_t aDirection, double aDelta)
{
  WidgetSimpleGestureEvent geckoEvent =
    CreateSwipeGestureEvent(aMsg, &mWidget, mEventPosition);
  geckoEvent.mDirection = aDirection;
  geckoEvent.mDelta = aDelta;
  geckoEvent.mAllowedDirections = mAllowedDirections;
  return mWidget.DispatchWindowEvent(geckoEvent);
}

} // namespace mozilla