ScrollController.mm [plain text]
/*
* Copyright (C) 2011, 2014-2015 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.
*/
#include "config.h"
#include "ScrollController.h"
#include "LayoutSize.h"
#include "PlatformWheelEvent.h"
#include "WebCoreSystemInterface.h"
#include "WheelEventTestTrigger.h"
#include <sys/sysctl.h>
#include <sys/time.h>
#include <wtf/CurrentTime.h>
#if ENABLE(CSS_SCROLL_SNAP)
#include "ScrollSnapAnimatorState.h"
#include "ScrollableArea.h"
#endif
#if ENABLE(RUBBER_BANDING) || ENABLE(CSS_SCROLL_SNAP)
#if PLATFORM(MAC)
static NSTimeInterval systemUptime()
{
if ([[NSProcessInfo processInfo] respondsToSelector:@selector(systemUptime)])
return [[NSProcessInfo processInfo] systemUptime];
// Get how long system has been up. Found by looking getting "boottime" from the kernel.
static struct timeval boottime = {0, 0};
if (!boottime.tv_sec) {
int mib[2] = {CTL_KERN, KERN_BOOTTIME};
size_t size = sizeof(boottime);
if (-1 == sysctl(mib, 2, &boottime, &size, 0, 0))
boottime.tv_sec = 0;
}
struct timeval now;
if (boottime.tv_sec && -1 != gettimeofday(&now, 0)) {
struct timeval uptime;
timersub(&now, &boottime, &uptime);
NSTimeInterval result = uptime.tv_sec + (uptime.tv_usec / 1E+6);
return result;
}
return 0;
}
#endif
namespace WebCore {
#if ENABLE(RUBBER_BANDING)
static const float scrollVelocityZeroingTimeout = 0.10f;
static const float rubberbandDirectionLockStretchRatio = 1;
static const float rubberbandMinimumRequiredDeltaBeforeStretch = 10;
#endif
#if ENABLE(CSS_SCROLL_SNAP) && PLATFORM(MAC)
static const float inertialScrollPredictionFactor = 16.7;
static const double statelessScrollSnapDelay = 0.5;
#endif
#if PLATFORM(MAC)
enum class WheelEventStatus {
UserScrollBegin,
UserScrolling,
UserScrollEnd,
InertialScrollBegin,
InertialScrolling,
InertialScrollEnd,
StatelessScrollEvent,
Unknown
};
static float elasticDeltaForTimeDelta(float initialPosition, float initialVelocity, float elapsedTime)
{
return wkNSElasticDeltaForTimeDelta(initialPosition, initialVelocity, elapsedTime);
}
static float elasticDeltaForReboundDelta(float delta)
{
return wkNSElasticDeltaForReboundDelta(delta);
}
static float reboundDeltaForElasticDelta(float delta)
{
return wkNSReboundDeltaForElasticDelta(delta);
}
static float scrollWheelMultiplier()
{
static float multiplier = -1;
if (multiplier < 0) {
multiplier = [[NSUserDefaults standardUserDefaults] floatForKey:@"NSScrollWheelMultiplier"];
if (multiplier <= 0)
multiplier = 1;
}
return multiplier;
}
#endif
ScrollController::ScrollController(ScrollControllerClient& client)
: m_client(client)
#if ENABLE(RUBBER_BANDING)
, m_snapRubberbandTimer(RunLoop::current(), this, &ScrollController::snapRubberBandTimerFired)
#endif
#if ENABLE(CSS_SCROLL_SNAP) && PLATFORM(MAC)
, m_scrollSnapTimer(RunLoop::current(), this, &ScrollController::scrollSnapTimerFired)
#endif
{
}
#if PLATFORM(MAC)
bool ScrollController::handleWheelEvent(const PlatformWheelEvent& wheelEvent)
{
#if ENABLE(CSS_SCROLL_SNAP)
if (!processWheelEventForScrollSnap(wheelEvent))
return false;
#endif
if (wheelEvent.phase() == PlatformWheelEventPhaseBegan) {
// First, check if we should rubber-band at all.
if (m_client.pinnedInDirection(FloatSize(-wheelEvent.deltaX(), 0))
&& !shouldRubberBandInHorizontalDirection(wheelEvent))
return false;
m_inScrollGesture = true;
m_momentumScrollInProgress = false;
m_ignoreMomentumScrolls = false;
m_lastMomentumScrollTimestamp = 0;
m_momentumVelocity = FloatSize();
IntSize stretchAmount = m_client.stretchAmount();
m_stretchScrollForce.setWidth(reboundDeltaForElasticDelta(stretchAmount.width()));
m_stretchScrollForce.setHeight(reboundDeltaForElasticDelta(stretchAmount.height()));
m_overflowScrollDelta = FloatSize();
stopSnapRubberbandTimer();
return true;
}
if (wheelEvent.phase() == PlatformWheelEventPhaseEnded) {
snapRubberBand();
return true;
}
bool isMomentumScrollEvent = (wheelEvent.momentumPhase() != PlatformWheelEventPhaseNone);
if (m_ignoreMomentumScrolls && (isMomentumScrollEvent || m_snapRubberbandTimerIsActive)) {
if (wheelEvent.momentumPhase() == PlatformWheelEventPhaseEnded) {
m_ignoreMomentumScrolls = false;
return true;
}
return false;
}
float deltaX = m_overflowScrollDelta.width();
float deltaY = m_overflowScrollDelta.height();
// Reset overflow values because we may decide to remove delta at various points and put it into overflow.
m_overflowScrollDelta = FloatSize();
IntSize stretchAmount = m_client.stretchAmount();
bool isVerticallyStretched = stretchAmount.height();
bool isHorizontallyStretched = stretchAmount.width();
float eventCoalescedDeltaX;
float eventCoalescedDeltaY;
if (isVerticallyStretched || isHorizontallyStretched) {
eventCoalescedDeltaX = -wheelEvent.unacceleratedScrollingDeltaX();
eventCoalescedDeltaY = -wheelEvent.unacceleratedScrollingDeltaY();
} else {
eventCoalescedDeltaX = -wheelEvent.deltaX();
eventCoalescedDeltaY = -wheelEvent.deltaY();
}
deltaX += eventCoalescedDeltaX;
deltaY += eventCoalescedDeltaY;
// Slightly prefer scrolling vertically by applying the = case to deltaY
if (fabsf(deltaY) >= fabsf(deltaX))
deltaX = 0;
else
deltaY = 0;
bool shouldStretch = false;
PlatformWheelEventPhase momentumPhase = wheelEvent.momentumPhase();
// If we are starting momentum scrolling then do some setup.
if (!m_momentumScrollInProgress && (momentumPhase == PlatformWheelEventPhaseBegan || momentumPhase == PlatformWheelEventPhaseChanged))
m_momentumScrollInProgress = true;
CFTimeInterval timeDelta = wheelEvent.timestamp() - m_lastMomentumScrollTimestamp;
if (m_inScrollGesture || m_momentumScrollInProgress) {
if (m_lastMomentumScrollTimestamp && timeDelta > 0 && timeDelta < scrollVelocityZeroingTimeout) {
m_momentumVelocity.setWidth(eventCoalescedDeltaX / (float)timeDelta);
m_momentumVelocity.setHeight(eventCoalescedDeltaY / (float)timeDelta);
m_lastMomentumScrollTimestamp = wheelEvent.timestamp();
} else {
m_lastMomentumScrollTimestamp = wheelEvent.timestamp();
m_momentumVelocity = FloatSize();
}
if (isVerticallyStretched) {
if (!isHorizontallyStretched && m_client.pinnedInDirection(FloatSize(deltaX, 0))) {
// Stretching only in the vertical.
if (deltaY && (fabsf(deltaX / deltaY) < rubberbandDirectionLockStretchRatio))
deltaX = 0;
else if (fabsf(deltaX) < rubberbandMinimumRequiredDeltaBeforeStretch) {
m_overflowScrollDelta.setWidth(m_overflowScrollDelta.width() + deltaX);
deltaX = 0;
} else
m_overflowScrollDelta.setWidth(m_overflowScrollDelta.width() + deltaX);
}
} else if (isHorizontallyStretched) {
// Stretching only in the horizontal.
if (m_client.pinnedInDirection(FloatSize(0, deltaY))) {
if (deltaX && (fabsf(deltaY / deltaX) < rubberbandDirectionLockStretchRatio))
deltaY = 0;
else if (fabsf(deltaY) < rubberbandMinimumRequiredDeltaBeforeStretch) {
m_overflowScrollDelta.setHeight(m_overflowScrollDelta.height() + deltaY);
deltaY = 0;
} else
m_overflowScrollDelta.setHeight(m_overflowScrollDelta.height() + deltaY);
}
} else {
// Not stretching at all yet.
if (m_client.pinnedInDirection(FloatSize(deltaX, deltaY))) {
if (fabsf(deltaY) >= fabsf(deltaX)) {
if (fabsf(deltaX) < rubberbandMinimumRequiredDeltaBeforeStretch) {
m_overflowScrollDelta.setWidth(m_overflowScrollDelta.width() + deltaX);
deltaX = 0;
} else
m_overflowScrollDelta.setWidth(m_overflowScrollDelta.width() + deltaX);
}
shouldStretch = true;
}
}
}
if (deltaX || deltaY) {
if (!(shouldStretch || isVerticallyStretched || isHorizontallyStretched)) {
if (deltaY) {
deltaY *= scrollWheelMultiplier();
m_client.immediateScrollBy(FloatSize(0, deltaY));
}
if (deltaX) {
deltaX *= scrollWheelMultiplier();
m_client.immediateScrollBy(FloatSize(deltaX, 0));
}
} else {
if (!m_client.allowsHorizontalStretching(wheelEvent)) {
deltaX = 0;
eventCoalescedDeltaX = 0;
} else if (deltaX && !isHorizontallyStretched && !m_client.pinnedInDirection(FloatSize(deltaX, 0))) {
deltaX *= scrollWheelMultiplier();
m_client.immediateScrollByWithoutContentEdgeConstraints(FloatSize(deltaX, 0));
deltaX = 0;
}
if (!m_client.allowsVerticalStretching(wheelEvent)) {
deltaY = 0;
eventCoalescedDeltaY = 0;
} else if (deltaY && !isVerticallyStretched && !m_client.pinnedInDirection(FloatSize(0, deltaY))) {
deltaY *= scrollWheelMultiplier();
m_client.immediateScrollByWithoutContentEdgeConstraints(FloatSize(0, deltaY));
deltaY = 0;
}
IntSize stretchAmount = m_client.stretchAmount();
if (m_momentumScrollInProgress) {
if ((m_client.pinnedInDirection(FloatSize(eventCoalescedDeltaX, eventCoalescedDeltaY)) || (fabsf(eventCoalescedDeltaX) + fabsf(eventCoalescedDeltaY) <= 0)) && m_lastMomentumScrollTimestamp) {
m_ignoreMomentumScrolls = true;
m_momentumScrollInProgress = false;
snapRubberBand();
}
}
m_stretchScrollForce.setWidth(m_stretchScrollForce.width() + deltaX);
m_stretchScrollForce.setHeight(m_stretchScrollForce.height() + deltaY);
FloatSize dampedDelta(ceilf(elasticDeltaForReboundDelta(m_stretchScrollForce.width())), ceilf(elasticDeltaForReboundDelta(m_stretchScrollForce.height())));
m_client.immediateScrollByWithoutContentEdgeConstraints(dampedDelta - stretchAmount);
}
}
if (m_momentumScrollInProgress && momentumPhase == PlatformWheelEventPhaseEnded) {
m_momentumScrollInProgress = false;
m_ignoreMomentumScrolls = false;
m_lastMomentumScrollTimestamp = 0;
}
return true;
}
#endif
#if ENABLE(RUBBER_BANDING)
static inline float roundTowardZero(float num)
{
return num > 0 ? ceilf(num - 0.5f) : floorf(num + 0.5f);
}
static inline float roundToDevicePixelTowardZero(float num)
{
float roundedNum = roundf(num);
if (fabs(num - roundedNum) < 0.125)
num = roundedNum;
return roundTowardZero(num);
}
void ScrollController::snapRubberBandTimerFired()
{
if (isScrollSnapInProgress())
return;
if (!m_momentumScrollInProgress || m_ignoreMomentumScrolls) {
CFTimeInterval timeDelta = [NSDate timeIntervalSinceReferenceDate] - m_startTime;
if (m_startStretch == FloatSize()) {
m_startStretch = m_client.stretchAmount();
if (m_startStretch == FloatSize()) {
stopSnapRubberbandTimer();
m_stretchScrollForce = FloatSize();
m_startTime = 0;
m_startStretch = FloatSize();
m_origOrigin = FloatPoint();
m_origVelocity = FloatSize();
return;
}
m_origOrigin = m_client.absoluteScrollPosition() - m_startStretch;
m_origVelocity = m_momentumVelocity;
// Just like normal scrolling, prefer vertical rubberbanding
if (fabsf(m_origVelocity.height()) >= fabsf(m_origVelocity.width()))
m_origVelocity.setWidth(0);
// Don't rubber-band horizontally if it's not possible to scroll horizontally
if (!m_client.canScrollHorizontally())
m_origVelocity.setWidth(0);
// Don't rubber-band vertically if it's not possible to scroll vertically
if (!m_client.canScrollVertically())
m_origVelocity.setHeight(0);
}
FloatPoint delta(roundToDevicePixelTowardZero(elasticDeltaForTimeDelta(m_startStretch.width(), -m_origVelocity.width(), (float)timeDelta)),
roundToDevicePixelTowardZero(elasticDeltaForTimeDelta(m_startStretch.height(), -m_origVelocity.height(), (float)timeDelta)));
if (fabs(delta.x()) >= 1 || fabs(delta.y()) >= 1) {
m_client.immediateScrollByWithoutContentEdgeConstraints(FloatSize(delta.x(), delta.y()) - m_client.stretchAmount());
FloatSize newStretch = m_client.stretchAmount();
m_stretchScrollForce.setWidth(reboundDeltaForElasticDelta(newStretch.width()));
m_stretchScrollForce.setHeight(reboundDeltaForElasticDelta(newStretch.height()));
} else {
m_client.adjustScrollPositionToBoundsIfNecessary();
stopSnapRubberbandTimer();
m_stretchScrollForce = FloatSize();
m_startTime = 0;
m_startStretch = FloatSize();
m_origOrigin = FloatPoint();
m_origVelocity = FloatSize();
}
} else {
m_startTime = [NSDate timeIntervalSinceReferenceDate];
m_startStretch = FloatSize();
if (!isRubberBandInProgress())
stopSnapRubberbandTimer();
}
}
#endif
bool ScrollController::isRubberBandInProgress() const
{
#if ENABLE(RUBBER_BANDING) && PLATFORM(MAC)
if (!m_inScrollGesture && !m_momentumScrollInProgress && !m_snapRubberbandTimerIsActive)
return false;
return !m_client.stretchAmount().isZero();
#else
return false;
#endif
}
bool ScrollController::isScrollSnapInProgress() const
{
#if ENABLE(CSS_SCROLL_SNAP) && PLATFORM(MAC)
if (m_inScrollGesture || m_momentumScrollInProgress || m_scrollSnapTimer.isActive())
return true;
#endif
return false;
}
#if ENABLE(RUBBER_BANDING)
void ScrollController::startSnapRubberbandTimer()
{
m_client.startSnapRubberbandTimer();
m_snapRubberbandTimer.startRepeating(1.0 / 60.0);
m_client.deferTestsForReason(reinterpret_cast<WheelEventTestTrigger::ScrollableAreaIdentifier>(this), WheelEventTestTrigger::RubberbandInProgress);
}
void ScrollController::stopSnapRubberbandTimer()
{
m_client.stopSnapRubberbandTimer();
m_snapRubberbandTimer.stop();
m_snapRubberbandTimerIsActive = false;
m_client.removeTestDeferralForReason(reinterpret_cast<WheelEventTestTrigger::ScrollableAreaIdentifier>(this), WheelEventTestTrigger::RubberbandInProgress);
}
void ScrollController::snapRubberBand()
{
CFTimeInterval timeDelta = systemUptime() - m_lastMomentumScrollTimestamp;
if (m_lastMomentumScrollTimestamp && timeDelta >= scrollVelocityZeroingTimeout)
m_momentumVelocity = FloatSize();
m_inScrollGesture = false;
if (m_snapRubberbandTimerIsActive)
return;
m_startTime = [NSDate timeIntervalSinceReferenceDate];
m_startStretch = FloatSize();
m_origOrigin = FloatPoint();
m_origVelocity = FloatSize();
startSnapRubberbandTimer();
m_snapRubberbandTimerIsActive = true;
}
bool ScrollController::shouldRubberBandInHorizontalDirection(const PlatformWheelEvent& wheelEvent)
{
if (wheelEvent.deltaX() > 0)
return m_client.shouldRubberBandInDirection(ScrollLeft);
if (wheelEvent.deltaX() < 0)
return m_client.shouldRubberBandInDirection(ScrollRight);
return true;
}
#endif
#if ENABLE(CSS_SCROLL_SNAP)
ScrollSnapAnimatorState& ScrollController::scrollSnapPointState(ScrollEventAxis axis)
{
ASSERT(axis != ScrollEventAxis::Horizontal || m_horizontalScrollSnapState);
ASSERT(axis != ScrollEventAxis::Vertical || m_verticalScrollSnapState);
return (axis == ScrollEventAxis::Horizontal) ? *m_horizontalScrollSnapState : *m_verticalScrollSnapState;
}
const ScrollSnapAnimatorState& ScrollController::scrollSnapPointState(ScrollEventAxis axis) const
{
ASSERT(axis != ScrollEventAxis::Horizontal || m_horizontalScrollSnapState);
ASSERT(axis != ScrollEventAxis::Vertical || m_verticalScrollSnapState);
return (axis == ScrollEventAxis::Horizontal) ? *m_horizontalScrollSnapState : *m_verticalScrollSnapState;
}
#if PLATFORM(MAC)
static inline WheelEventStatus toWheelEventStatus(PlatformWheelEventPhase phase, PlatformWheelEventPhase momentumPhase)
{
if (phase == PlatformWheelEventPhaseNone) {
switch (momentumPhase) {
case PlatformWheelEventPhaseBegan:
return WheelEventStatus::InertialScrollBegin;
case PlatformWheelEventPhaseChanged:
return WheelEventStatus::InertialScrolling;
case PlatformWheelEventPhaseEnded:
return WheelEventStatus::InertialScrollEnd;
case PlatformWheelEventPhaseNone:
return WheelEventStatus::StatelessScrollEvent;
default:
return WheelEventStatus::Unknown;
}
}
if (momentumPhase == PlatformWheelEventPhaseNone) {
switch (phase) {
case PlatformWheelEventPhaseBegan:
case PlatformWheelEventPhaseMayBegin:
return WheelEventStatus::UserScrollBegin;
case PlatformWheelEventPhaseChanged:
return WheelEventStatus::UserScrolling;
case PlatformWheelEventPhaseEnded:
case PlatformWheelEventPhaseCancelled:
return WheelEventStatus::UserScrollEnd;
default:
return WheelEventStatus::Unknown;
}
}
return WheelEventStatus::Unknown;
}
void ScrollController::processWheelEventForScrollSnapOnAxis(ScrollEventAxis axis, const PlatformWheelEvent& event)
{
ScrollSnapAnimatorState& snapState = scrollSnapPointState(axis);
float wheelDelta = axis == ScrollEventAxis::Horizontal ? -event.deltaX() : -event.deltaY();
WheelEventStatus wheelStatus = toWheelEventStatus(event.phase(), event.momentumPhase());
switch (wheelStatus) {
case WheelEventStatus::UserScrollBegin:
case WheelEventStatus::UserScrolling:
endScrollSnapAnimation(ScrollSnapState::UserInteraction);
break;
case WheelEventStatus::UserScrollEnd:
beginScrollSnapAnimation(axis, ScrollSnapState::Snapping);
break;
case WheelEventStatus::InertialScrollBegin:
// Begin tracking wheel deltas for glide prediction.
endScrollSnapAnimation(ScrollSnapState::UserInteraction);
snapState.pushInitialWheelDelta(wheelDelta);
snapState.m_beginTrackingWheelDeltaOffset = m_client.scrollOffsetOnAxis(axis);
break;
case WheelEventStatus::InertialScrolling:
// This check for DestinationReached ensures that we don't receive another set of momentum events after ending the last glide.
if (snapState.m_currentState != ScrollSnapState::Gliding && snapState.m_currentState != ScrollSnapState::DestinationReached) {
if (snapState.m_numWheelDeltasTracked < snapState.wheelDeltaWindowSize && wheelDelta)
snapState.pushInitialWheelDelta(wheelDelta);
if ((snapState.m_numWheelDeltasTracked == snapState.wheelDeltaWindowSize) && snapState.averageInitialWheelDelta())
beginScrollSnapAnimation(axis, ScrollSnapState::Gliding);
}
break;
case WheelEventStatus::InertialScrollEnd:
snapState.clearInitialWheelDeltaWindow();
snapState.m_shouldOverrideWheelEvent = false;
break;
case WheelEventStatus::StatelessScrollEvent:
endScrollSnapAnimation(ScrollSnapState::UserInteraction);
snapState.clearInitialWheelDeltaWindow();
snapState.m_shouldOverrideWheelEvent = false;
m_scrollSnapTimer.startOneShot(statelessScrollSnapDelay);
if (axis == ScrollEventAxis::Horizontal)
m_expectingHorizontalStatelessScrollSnap = true;
else
m_expectingVerticalStatelessScrollSnap = true;
break;
case WheelEventStatus::Unknown:
ASSERT_NOT_REACHED();
break;
}
}
bool ScrollController::shouldOverrideWheelEvent(ScrollEventAxis axis, const PlatformWheelEvent& event) const
{
const ScrollSnapAnimatorState& snapState = scrollSnapPointState(axis);
return snapState.m_shouldOverrideWheelEvent && toWheelEventStatus(event.phase(), event.momentumPhase()) == WheelEventStatus::InertialScrolling;
}
bool ScrollController::processWheelEventForScrollSnap(const PlatformWheelEvent& wheelEvent)
{
bool shouldAllowWheelEventToPropagate = true;
if (m_verticalScrollSnapState) {
processWheelEventForScrollSnapOnAxis(ScrollEventAxis::Vertical, wheelEvent);
shouldAllowWheelEventToPropagate &= !shouldOverrideWheelEvent(ScrollEventAxis::Vertical, wheelEvent);
}
if (m_horizontalScrollSnapState) {
processWheelEventForScrollSnapOnAxis(ScrollEventAxis::Horizontal, wheelEvent);
shouldAllowWheelEventToPropagate &= !shouldOverrideWheelEvent(ScrollEventAxis::Horizontal, wheelEvent);
}
return shouldAllowWheelEventToPropagate;
}
#endif
void ScrollController::updateScrollSnapState(const ScrollableArea& scrollableArea)
{
// FIXME: Currently, scroll snap animators are recreated even though the snap offsets alone can be updated.
if (scrollableArea.horizontalSnapOffsets())
m_horizontalScrollSnapState = std::make_unique<ScrollSnapAnimatorState>(ScrollEventAxis::Horizontal, *scrollableArea.horizontalSnapOffsets());
else if (m_horizontalScrollSnapState)
m_horizontalScrollSnapState = nullptr;
if (scrollableArea.verticalSnapOffsets())
m_verticalScrollSnapState = std::make_unique<ScrollSnapAnimatorState>(ScrollEventAxis::Vertical, *scrollableArea.verticalSnapOffsets());
else if (m_verticalScrollSnapState)
m_verticalScrollSnapState = nullptr;
}
void ScrollController::updateScrollSnapPoints(ScrollEventAxis axis, const Vector<LayoutUnit>& snapPoints)
{
// FIXME: Currently, scroll snap animators are recreated even though the snap offsets alone can be updated.
if (axis == ScrollEventAxis::Horizontal)
m_horizontalScrollSnapState = !snapPoints.isEmpty() ? std::make_unique<ScrollSnapAnimatorState>(ScrollEventAxis::Horizontal, snapPoints) : nullptr;
if (axis == ScrollEventAxis::Vertical)
m_verticalScrollSnapState = !snapPoints.isEmpty() ? std::make_unique<ScrollSnapAnimatorState>(ScrollEventAxis::Vertical, snapPoints) : nullptr;
}
#if PLATFORM(MAC)
void ScrollController::startScrollSnapTimer()
{
if (!m_scrollSnapTimer.isActive()) {
m_client.startScrollSnapTimer();
m_scrollSnapTimer.startRepeating(1.0 / 60.0);
}
if (!m_scrollSnapTimer.isActive())
return;
m_client.deferTestsForReason(reinterpret_cast<WheelEventTestTrigger::ScrollableAreaIdentifier>(this), WheelEventTestTrigger::ScrollSnapInProgress);
}
void ScrollController::stopScrollSnapTimer()
{
m_client.stopScrollSnapTimer();
m_scrollSnapTimer.stop();
if (m_scrollSnapTimer.isActive())
return;
m_client.removeTestDeferralForReason(reinterpret_cast<WheelEventTestTrigger::ScrollableAreaIdentifier>(this), WheelEventTestTrigger::ScrollSnapInProgress);
}
void ScrollController::scrollSnapTimerFired()
{
if (m_expectingHorizontalStatelessScrollSnap || m_expectingVerticalStatelessScrollSnap) {
if (m_expectingHorizontalStatelessScrollSnap)
beginScrollSnapAnimation(ScrollEventAxis::Horizontal, ScrollSnapState::Snapping);
if (m_expectingVerticalStatelessScrollSnap)
beginScrollSnapAnimation(ScrollEventAxis::Vertical, ScrollSnapState::Snapping);
return;
}
bool snapOnHorizontalAxis = isSnappingOnAxis(ScrollEventAxis::Horizontal);
bool snapOnVerticalAxis = isSnappingOnAxis(ScrollEventAxis::Vertical);
if (snapOnHorizontalAxis && !m_horizontalScrollSnapState->canReachTargetWithCurrentInitialScrollDelta()) {
m_horizontalScrollSnapState->m_currentState = ScrollSnapState::DestinationReached;
snapOnHorizontalAxis = false;
}
if (snapOnVerticalAxis && !m_verticalScrollSnapState->canReachTargetWithCurrentInitialScrollDelta()) {
m_verticalScrollSnapState->m_currentState = ScrollSnapState::DestinationReached;
snapOnVerticalAxis = false;
}
if (!snapOnHorizontalAxis && !snapOnVerticalAxis) {
endScrollSnapAnimation(ScrollSnapState::DestinationReached);
return;
}
double currentTime = monotonicallyIncreasingTime();
if (m_scrollSnapCurveState->shouldCompleteSnapAnimationImmediatelyAtTime(currentTime)) {
float finalHorizontalDelta = 0;
float finalVerticalDelta = 0;
if (snapOnHorizontalAxis)
finalHorizontalDelta = m_horizontalScrollSnapState->m_targetOffset - m_client.scrollOffsetOnAxis(ScrollEventAxis::Horizontal);
if (snapOnVerticalAxis)
finalVerticalDelta = m_verticalScrollSnapState->m_targetOffset - m_client.scrollOffsetOnAxis(ScrollEventAxis::Vertical);
if (finalHorizontalDelta || finalVerticalDelta)
m_client.immediateScrollBy(FloatSize(finalHorizontalDelta, finalVerticalDelta));
endScrollSnapAnimation(ScrollSnapState::DestinationReached);
return;
}
float animationProgress = m_scrollSnapCurveState->animationProgressAtTime(currentTime);
float horizontalDelta = 0;
float verticalDelta = 0;
if (m_scrollSnapCurveState->shouldAnimateDirectlyToSnapPoint) {
if (snapOnHorizontalAxis)
horizontalDelta = m_horizontalScrollSnapState->interpolatedOffsetAtProgress(animationProgress) - m_client.scrollOffsetOnAxis(ScrollEventAxis::Horizontal);
if (snapOnVerticalAxis)
verticalDelta = m_verticalScrollSnapState->interpolatedOffsetAtProgress(animationProgress) - m_client.scrollOffsetOnAxis(ScrollEventAxis::Vertical);
} else {
FloatPoint interpolatedPoint = m_scrollSnapCurveState->interpolatedPositionAtProgress(animationProgress);
horizontalDelta = interpolatedPoint.x() - m_client.scrollOffsetOnAxis(ScrollEventAxis::Horizontal);
verticalDelta = interpolatedPoint.y() - m_client.scrollOffsetOnAxis(ScrollEventAxis::Vertical);
}
if (horizontalDelta || verticalDelta)
m_client.immediateScrollBy(FloatSize(horizontalDelta, verticalDelta));
}
static inline float projectedInertialScrollDistance(float initialWheelDelta)
{
// FIXME: Experiments with inertial scrolling show a fairly consistent linear relationship between initial wheel delta and total distance scrolled.
// In the future, we'll want to find a more accurate way of inertial scroll prediction.
return inertialScrollPredictionFactor * initialWheelDelta;
}
#endif
unsigned ScrollController::activeScrollSnapIndexForAxis(ScrollEventAxis axis) const
{
if ((axis == ScrollEventAxis::Horizontal) && !m_horizontalScrollSnapState)
return 0;
if ((axis == ScrollEventAxis::Vertical) && !m_verticalScrollSnapState)
return 0;
const ScrollSnapAnimatorState& snapState = scrollSnapPointState(axis);
return snapState.m_activeSnapIndex;
}
void ScrollController::setActiveScrollSnapIndexForAxis(ScrollEventAxis axis, unsigned index)
{
auto* snapState = (axis == ScrollEventAxis::Horizontal) ? m_horizontalScrollSnapState.get() : m_verticalScrollSnapState.get();
if (!snapState)
return;
snapState->m_activeSnapIndex = index;
}
void ScrollController::setNearestScrollSnapIndexForAxisAndOffset(ScrollEventAxis axis, int offset)
{
float scaleFactor = m_client.pageScaleFactor();
ScrollSnapAnimatorState& snapState = scrollSnapPointState(axis);
LayoutUnit clampedOffset = std::min(std::max(LayoutUnit(offset / scaleFactor), snapState.m_snapOffsets.first()), snapState.m_snapOffsets.last());
unsigned activeIndex = 0;
(void)closestSnapOffset<LayoutUnit, float>(snapState.m_snapOffsets, clampedOffset, 0, activeIndex);
if (activeIndex == snapState.m_activeSnapIndex)
return;
m_activeScrollSnapIndexDidChange = true;
snapState.m_activeSnapIndex = activeIndex;
}
void ScrollController::setActiveScrollSnapIndicesForOffset(int x, int y)
{
if (m_horizontalScrollSnapState)
setNearestScrollSnapIndexForAxisAndOffset(ScrollEventAxis::Horizontal, x);
if (m_verticalScrollSnapState)
setNearestScrollSnapIndexForAxisAndOffset(ScrollEventAxis::Vertical, y);
}
#if PLATFORM(MAC)
void ScrollController::beginScrollSnapAnimation(ScrollEventAxis axis, ScrollSnapState newState)
{
ASSERT(newState == ScrollSnapState::Gliding || newState == ScrollSnapState::Snapping);
if (m_expectingHorizontalStatelessScrollSnap || m_expectingVerticalStatelessScrollSnap) {
m_expectingHorizontalStatelessScrollSnap = false;
m_expectingVerticalStatelessScrollSnap = false;
stopScrollSnapTimer();
}
ScrollSnapAnimatorState& snapState = scrollSnapPointState(axis);
LayoutUnit offset = m_client.scrollOffsetOnAxis(axis);
float initialWheelDelta = newState == ScrollSnapState::Gliding ? snapState.averageInitialWheelDelta() : 0;
LayoutUnit scaledProjectedScrollDestination = newState == ScrollSnapState::Gliding ? snapState.m_beginTrackingWheelDeltaOffset + LayoutUnit(projectedInertialScrollDistance(initialWheelDelta)) : offset;
if (snapState.m_snapOffsets.isEmpty())
return;
float scaleFactor = m_client.pageScaleFactor();
LayoutUnit originalProjectedScrollDestination = scaledProjectedScrollDestination / scaleFactor;
LayoutUnit clampedScrollDestination = std::min(std::max(originalProjectedScrollDestination, snapState.m_snapOffsets.first()), snapState.m_snapOffsets.last());
snapState.m_initialOffset = offset;
m_activeScrollSnapIndexDidChange = false;
snapState.m_targetOffset = scaleFactor * closestSnapOffset<LayoutUnit, float>(snapState.m_snapOffsets, clampedScrollDestination, initialWheelDelta, snapState.m_activeSnapIndex);
if (snapState.m_initialOffset == snapState.m_targetOffset)
return;
LayoutUnit scrollExtent = (axis == ScrollEventAxis::Horizontal) ? m_client.scrollExtent().width() : m_client.scrollExtent().height();
LayoutUnit projectedScrollDestination = clampedScrollDestination;
if (originalProjectedScrollDestination < 0 || originalProjectedScrollDestination > scrollExtent)
projectedScrollDestination = originalProjectedScrollDestination;
m_activeScrollSnapIndexDidChange = true;
snapState.m_currentState = newState;
if (newState == ScrollSnapState::Gliding) {
// Check if the other scroll axis needs to animate to the nearest snap point.
snapState.m_initialScrollDelta = initialWheelDelta;
snapState.m_shouldOverrideWheelEvent = true;
snapState.clearInitialWheelDeltaWindow();
ScrollEventAxis otherAxis = axis == ScrollEventAxis::Horizontal ? ScrollEventAxis::Vertical : ScrollEventAxis::Horizontal;
if ((otherAxis == ScrollEventAxis::Horizontal && m_horizontalScrollSnapState && m_horizontalScrollSnapState->m_currentState == ScrollSnapState::UserInteraction)
|| (otherAxis == ScrollEventAxis::Vertical && m_verticalScrollSnapState && m_verticalScrollSnapState->m_currentState == ScrollSnapState::UserInteraction)) {
ScrollSnapAnimatorState& otherState = scrollSnapPointState(otherAxis);
if (!otherState.averageInitialWheelDelta()) {
float offsetOnOtherAxis = m_client.scrollOffsetOnAxis(otherAxis);
float snapOffsetForOtherAxis = scaleFactor * closestSnapOffset<LayoutUnit, float>(otherState.m_snapOffsets, offsetOnOtherAxis, 0, otherState.m_activeSnapIndex);
if (offsetOnOtherAxis != snapOffsetForOtherAxis) {
otherState.m_initialOffset = offsetOnOtherAxis;
otherState.m_targetOffset = snapOffsetForOtherAxis;
otherState.m_initialScrollDelta = 0;
otherState.m_currentState = ScrollSnapState::Gliding;
}
}
}
} else {
snapState.m_initialScrollDelta = initialWheelDelta;
}
initializeScrollSnapAnimationParameters();
startScrollSnapTimer();
}
void ScrollController::endScrollSnapAnimation(ScrollSnapState newState)
{
ASSERT(newState == ScrollSnapState::DestinationReached || newState == ScrollSnapState::UserInteraction);
if (m_horizontalScrollSnapState)
m_horizontalScrollSnapState->m_currentState = newState;
if (m_verticalScrollSnapState)
m_verticalScrollSnapState->m_currentState = newState;
stopScrollSnapTimer();
}
void ScrollController::initializeScrollSnapAnimationParameters()
{
if (!m_scrollSnapCurveState)
m_scrollSnapCurveState = std::make_unique<ScrollSnapAnimationCurveState>();
bool isSnappingOnHorizontalAxis = isSnappingOnAxis(ScrollEventAxis::Horizontal);
bool isSnappingOnVerticalAxis = isSnappingOnAxis(ScrollEventAxis::Vertical);
FloatSize initialVector(isSnappingOnHorizontalAxis ? m_horizontalScrollSnapState->m_initialOffset : m_client.scrollOffsetOnAxis(ScrollEventAxis::Horizontal),
isSnappingOnVerticalAxis ? m_verticalScrollSnapState->m_initialOffset : m_client.scrollOffsetOnAxis(ScrollEventAxis::Vertical));
FloatSize targetVector(isSnappingOnHorizontalAxis ? m_horizontalScrollSnapState->m_targetOffset : m_client.scrollOffsetOnAxis(ScrollEventAxis::Horizontal),
isSnappingOnVerticalAxis ? m_verticalScrollSnapState->m_targetOffset : m_client.scrollOffsetOnAxis(ScrollEventAxis::Vertical));
FloatSize initialDelta(isSnappingOnHorizontalAxis ? m_horizontalScrollSnapState->m_initialScrollDelta : 0,
isSnappingOnVerticalAxis ? m_verticalScrollSnapState->m_initialScrollDelta : 0);
// Animate directly by default. This flag will be changed as necessary if interpolation is possible.
m_scrollSnapCurveState->shouldAnimateDirectlyToSnapPoint = true;
m_scrollSnapCurveState->initializeSnapProgressCurve(initialVector, targetVector, initialDelta);
if (isSnappingOnHorizontalAxis && isSnappingOnVerticalAxis)
m_scrollSnapCurveState->initializeInterpolationCoefficientsIfNecessary(initialVector, targetVector, initialDelta);
}
bool ScrollController::isSnappingOnAxis(ScrollEventAxis axis) const
{
if (axis == ScrollEventAxis::Horizontal)
return m_horizontalScrollSnapState && m_horizontalScrollSnapState->isSnapping();
return m_verticalScrollSnapState && m_verticalScrollSnapState->isSnapping();
}
#endif
#endif
} // namespace WebCore
#endif // ENABLE(RUBBER_BANDING)