ScrollElasticityController.mm [plain text]
/*
* 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 "ScrollElasticityController.h"
#include "PlatformWheelEvent.h"
#include "WebCoreSystemInterface.h"
#include <sys/time.h>
#include <sys/sysctl.h>
#if ENABLE(RUBBER_BANDING)
#ifdef BUILDING_ON_LEOPARD
@interface NSProcessInfo (ScrollAnimatorMacExt)
- (NSTimeInterval)systemUptime;
@end
#endif
#if ENABLE(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;
}
#endif
namespace WebCore {
static const float scrollVelocityZeroingTimeout = 0.10f;
static const float rubberbandDirectionLockStretchRatio = 1;
static const float rubberbandMinimumRequiredDeltaBeforeStretch = 10;
#if defined(BUILDING_ON_LEOPARD) || defined(BULDING_ON_SNOW_LEOPARD) || defined(BUILDING_ON_LION)
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;
}
#else
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);
}
#endif
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) {
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 != 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_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->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_startTime = [NSDate timeIntervalSinceReferenceDate];
m_startStretch = FloatSize();
m_origOrigin = FloatPoint();
m_origVelocity = FloatSize();
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 // ENABLE(RUBBER_BANDING)