| /* |
| * 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. |
| */ |
| |
| #include "config.h" |
| #include "core/platform/mac/ScrollElasticityController.h" |
| |
| #include "platform/PlatformWheelEvent.h" |
| #include <sys/sysctl.h> |
| #include <sys/time.h> |
| |
| #if USE(RUBBER_BANDING) |
| |
| 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; |
| } |
| |
| namespace WebCore { |
| |
| static const float scrollVelocityZeroingTimeout = 0.10f; |
| static const float rubberbandDirectionLockStretchRatio = 1; |
| static const float rubberbandMinimumRequiredDeltaBeforeStretch = 10; |
| |
| static const float rubberbandStiffness = 20; |
| static const float rubberbandAmplitude = 0.31f; |
| static const float rubberbandPeriod = 1.6f; |
| |
| static float elasticDeltaForTimeDelta(float initialPosition, float initialVelocity, float elapsedTime) |
| { |
| float amplitude = rubberbandAmplitude; |
| float period = rubberbandPeriod; |
| float criticalDampeningFactor = expf((-elapsedTime * rubberbandStiffness) / period); |
| |
| return (initialPosition + (-initialVelocity * elapsedTime * amplitude)) * criticalDampeningFactor; |
| } |
| |
| static float elasticDeltaForReboundDelta(float delta) |
| { |
| float stiffness = std::max(rubberbandStiffness, 1.0f); |
| return delta / stiffness; |
| } |
| |
| static float reboundDeltaForElasticDelta(float delta) |
| { |
| return delta * rubberbandStiffness; |
| } |
| |
| static float scrollWheelMultiplier() |
| { |
| static float multiplier = -1; |
| if (multiplier < 0) { |
| multiplier = [[NSUserDefaults standardUserDefaults] floatForKey:@"NSScrollWheelMultiplier"]; |
| if (multiplier <= 0) |
| multiplier = 1; |
| } |
| return multiplier; |
| } |
| |
| ScrollElasticityController::ScrollElasticityController(ScrollElasticityControllerClient* client) |
| : m_client(client) |
| , m_inScrollGesture(false) |
| , m_momentumScrollInProgress(false) |
| , m_ignoreMomentumScrolls(false) |
| , m_lastMomentumScrollTimestamp(0) |
| , m_startTime(0) |
| , m_snapRubberbandTimerIsActive(false) |
| { |
| } |
| |
| bool ScrollElasticityController::handleWheelEvent(const PlatformWheelEvent& wheelEvent) |
| { |
| 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) { |
| bool wasRubberBandInProgress = isRubberBandInProgress(); |
| // Call snapRubberBand() even if isRubberBandInProgress() is false. For example, |
| // m_inScrollGesture may be true (and needs to be reset on a phase end) even if |
| // isRubberBandInProgress() is not (e.g. the overhang area is empty). |
| snapRubberBand(); |
| return wasRubberBandInProgress; |
| } |
| |
| 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; |
| // Start the snap rubber band timer if it's not running. This is needed to |
| // snap back from the over scroll caused by momentum events. |
| if (!m_snapRubberbandTimerIsActive && m_startTime == 0) |
| snapRubberBand(); |
| } |
| |
| 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 != 0 && (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 != 0 && (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 != 0 || deltaY != 0) { |
| if (!(shouldStretch || isVerticallyStretched || isHorizontallyStretched)) { |
| if (deltaY != 0) { |
| deltaY *= scrollWheelMultiplier(); |
| m_client->immediateScrollBy(FloatSize(0, deltaY)); |
| } |
| if (deltaX != 0) { |
| deltaX *= scrollWheelMultiplier(); |
| m_client->immediateScrollBy(FloatSize(deltaX, 0)); |
| } |
| } else { |
| if (!m_client->allowsHorizontalStretching()) { |
| deltaX = 0; |
| eventCoalescedDeltaX = 0; |
| } else if ((deltaX != 0) && !isHorizontallyStretched && !m_client->pinnedInDirection(FloatSize(deltaX, 0))) { |
| deltaX *= scrollWheelMultiplier(); |
| |
| m_client->immediateScrollByWithoutContentEdgeConstraints(FloatSize(deltaX, 0)); |
| deltaX = 0; |
| } |
| |
| if (!m_client->allowsVerticalStretching()) { |
| deltaY = 0; |
| eventCoalescedDeltaY = 0; |
| } else if ((deltaY != 0) && !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; |
| } |
| |
| 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 ScrollElasticityController::snapRubberBandTimerFired() |
| { |
| 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_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->immediateScrollBy(m_origOrigin - m_client->absoluteScrollPosition()); |
| |
| stopSnapRubberbandTimer(); |
| m_stretchScrollForce = FloatSize(); |
| m_startTime = 0; |
| m_startStretch = FloatSize(); |
| m_origOrigin = FloatPoint(); |
| m_origVelocity = FloatSize(); |
| } |
| } else { |
| m_startTime = [NSDate timeIntervalSinceReferenceDate]; |
| m_startStretch = FloatSize(); |
| } |
| } |
| |
| bool ScrollElasticityController::isRubberBandInProgress() const |
| { |
| if (!m_inScrollGesture && !m_momentumScrollInProgress && !m_snapRubberbandTimerIsActive) |
| return false; |
| |
| return !m_client->stretchAmount().isZero(); |
| } |
| |
| void ScrollElasticityController::stopSnapRubberbandTimer() |
| { |
| m_client->stopSnapRubberbandTimer(); |
| m_snapRubberbandTimerIsActive = false; |
| } |
| |
| void ScrollElasticityController::snapRubberBand() |
| { |
| CFTimeInterval timeDelta = systemUptime() - m_lastMomentumScrollTimestamp; |
| if (m_lastMomentumScrollTimestamp && timeDelta >= scrollVelocityZeroingTimeout) |
| m_momentumVelocity = FloatSize(); |
| |
| m_inScrollGesture = false; |
| |
| if (m_snapRubberbandTimerIsActive) |
| return; |
| |
| m_startStretch = FloatSize(); |
| m_origOrigin = FloatPoint(); |
| m_origVelocity = FloatSize(); |
| |
| // If there's no momentum scroll or stretch amount, no need to start the timer. |
| if (!m_momentumScrollInProgress && m_client->stretchAmount() == FloatSize()) { |
| m_startTime = 0; |
| m_stretchScrollForce = FloatSize(); |
| return; |
| } |
| |
| m_startTime = [NSDate timeIntervalSinceReferenceDate]; |
| m_client->startSnapRubberbandTimer(); |
| m_snapRubberbandTimerIsActive = true; |
| } |
| |
| bool ScrollElasticityController::shouldRubberBandInHorizontalDirection(const PlatformWheelEvent& wheelEvent) |
| { |
| if (wheelEvent.deltaX() > 0) |
| return m_client->shouldRubberBandInDirection(ScrollLeft); |
| if (wheelEvent.deltaX() < 0) |
| return m_client->shouldRubberBandInDirection(ScrollRight); |
| |
| return true; |
| } |
| |
| } // namespace WebCore |
| |
| #endif // USE(RUBBER_BANDING) |
