float Axis::AdjustDisplacement(float aDisplacement, float& aOverscrollAmountOut,
bool aScrollingDisabled) {
if (mAxisLocked) {
aOverscrollAmountOut = 0;
return 0;
}
if (aScrollingDisabled) {
// Scrolling is disabled on this axis, stop scrolling.
aOverscrollAmountOut = aDisplacement;
return 0;
}
float displacement = aDisplacement;
// If this displacement will cause an overscroll, throttle it. Can potentially
// bring it to 0 even if the velocity is high.
if (DisplacementWillOverscroll(displacement) != OVERSCROLL_NONE) {
// No need to have a velocity along this axis anymore; it won't take us
// anywhere, so we're just spinning needlessly.
mVelocity = 0.0f;
aOverscrollAmountOut = DisplacementWillOverscrollAmount(displacement);
displacement -= aOverscrollAmountOut;
}
return displacement;
}
bool Axis::AdjustDisplacement(CSSCoord aDisplacement,
CSSCoord& aDisplacementOut,
CSSCoord& aOverscrollAmountOut)
{
if (mAxisLocked) {
aOverscrollAmountOut = 0;
aDisplacementOut = 0;
return false;
}
CSSCoord displacement = aDisplacement;
// First consume any overscroll in the opposite direction along this axis.
CSSCoord consumedOverscroll = 0;
if (mOverscroll > 0 && aDisplacement < 0) {
consumedOverscroll = std::min(mOverscroll, -aDisplacement);
} else if (mOverscroll < 0 && aDisplacement > 0) {
consumedOverscroll = 0.f - std::min(-mOverscroll, aDisplacement);
}
mOverscroll -= consumedOverscroll;
displacement += consumedOverscroll;
// Split the requested displacement into an allowed displacement that does
// not overscroll, and an overscroll amount.
if (DisplacementWillOverscroll(displacement) != OVERSCROLL_NONE) {
// No need to have a velocity along this axis anymore; it won't take us
// anywhere, so we're just spinning needlessly.
mVelocity = 0.0f;
aOverscrollAmountOut = DisplacementWillOverscrollAmount(displacement);
displacement -= aOverscrollAmountOut;
}
aDisplacementOut = displacement;
return fabsf(consumedOverscroll) > EPSILON;
}
bool Axis::CanScroll(ParentLayerCoord aDelta) const
{
if (!CanScroll() || mAxisLocked) {
return false;
}
return fabs(DisplacementWillOverscrollAmount(aDelta) - aDelta) > COORDINATE_EPSILON;
}
bool Axis::CanScroll(ParentLayerCoord aDelta) const
{
if (!CanScroll() || mAxisLocked) {
return false;
}
return DisplacementWillOverscrollAmount(aDelta) != aDelta;
}
bool Axis::CanScroll(double aDelta) const
{
if (!CanScroll() || mAxisLocked) {
return false;
}
ParentLayerCoord delta = aDelta;
return DisplacementWillOverscrollAmount(delta) != delta;
}
bool Axis::AdjustDisplacement(ParentLayerCoord aDisplacement,
/* ParentLayerCoord */ float& aDisplacementOut,
/* ParentLayerCoord */ float&
aOverscrollAmountOut,
bool forceOverscroll /* = false */)
{
if (mAxisLocked) {
aOverscrollAmountOut = 0;
aDisplacementOut = 0;
return false;
}
if (forceOverscroll) {
aOverscrollAmountOut = aDisplacement;
aDisplacementOut = 0;
return false;
}
StopSamplingOverscrollAnimation();
ParentLayerCoord displacement = aDisplacement;
// First consume any overscroll in the opposite direction along this axis.
ParentLayerCoord consumedOverscroll = 0;
if (mOverscroll > 0 && aDisplacement < 0) {
consumedOverscroll = std::min(mOverscroll, -aDisplacement);
} else if (mOverscroll < 0 && aDisplacement > 0) {
consumedOverscroll = 0.f - std::min(-mOverscroll, aDisplacement);
}
mOverscroll -= consumedOverscroll;
displacement += consumedOverscroll;
// Split the requested displacement into an allowed displacement that does
// not overscroll, and an overscroll amount.
aOverscrollAmountOut = DisplacementWillOverscrollAmount(displacement);
if (aOverscrollAmountOut != 0.0f) {
// No need to have a velocity along this axis anymore; it won't take us
// anywhere, so we're just spinning needlessly.
AXIS_LOG("%p|%s has overscrolled, clearing velocity\n",
mAsyncPanZoomController, Name());
mVelocity = 0.0f;
displacement -= aOverscrollAmountOut;
}
aDisplacementOut = displacement;
return fabsf(consumedOverscroll) > EPSILON;
}
float Axis::GetDisplacementForDuration(float aScale, const TimeDuration& aDelta) {
if (fabsf(mVelocity) < gVelocityThreshold) {
mAcceleration = 0;
}
float accelerationFactor = GetAccelerationFactor();
float displacement = mVelocity * aScale * aDelta.ToMilliseconds() * accelerationFactor;
// If this displacement will cause an overscroll, throttle it. Can potentially
// bring it to 0 even if the velocity is high.
if (DisplacementWillOverscroll(displacement) != OVERSCROLL_NONE) {
// No need to have a velocity along this axis anymore; it won't take us
// anywhere, so we're just spinning needlessly.
mVelocity = 0.0f;
mAcceleration = 0;
displacement -= DisplacementWillOverscrollAmount(displacement);
}
return displacement;
}
