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/* -*- 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
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