void ScrollView::startAutoScroll(const Vec2& deltaMove, float timeInSec, bool attenuated)
{
Vec2 adjustedDeltaMove = flattenVectorByDirection(deltaMove);
_autoScrolling = true;
_autoScrollTargetDelta = adjustedDeltaMove;
_autoScrollAttenuate = attenuated;
_autoScrollStartPosition = _innerContainer->getPosition();
_autoScrollTotalTime = timeInSec;
_autoScrollAccumulatedTime = 0;
_autoScrollBraking = false;
_autoScrollBrakingStartPosition = Vec2::ZERO;
// If the destination is also out of boundary of same side, start brake from beginning.
Vec2 currentOutOfBoundary = getHowMuchOutOfBoundary();
if (!fltEqualZero(currentOutOfBoundary))
{
_autoScrollCurrentlyOutOfBoundary = true;
Vec2 afterOutOfBoundary = getHowMuchOutOfBoundary(adjustedDeltaMove);
if(currentOutOfBoundary.x * afterOutOfBoundary.x > 0 || currentOutOfBoundary.y * afterOutOfBoundary.y > 0)
{
_autoScrollBraking = true;
}
}
}
void ScrollView::processAutoScrolling(float deltaTime)
{
// Make auto scroll shorter if it needs to deaccelerate.
float brakingFactor = (isNecessaryAutoScrollBrake() ? OUT_OF_BOUNDARY_BREAKING_FACTOR : 1);
// Elapsed time
_autoScrollAccumulatedTime += deltaTime * (1 / brakingFactor);
// Calculate the progress percentage
float percentage = MIN(1, _autoScrollAccumulatedTime / _autoScrollTotalTime);
if(_autoScrollAttenuate)
{
// Use quintic(5th degree) polynomial
percentage = tweenfunc::quintEaseOut(percentage);
}
// Calculate the new position
Vec2 newPosition = _autoScrollStartPosition + (_autoScrollTargetDelta * percentage);
bool reachedEnd = std::abs(percentage - 1) <= this->getAutoScrollStopEpsilon();
if (reachedEnd)
{
newPosition = _autoScrollStartPosition + _autoScrollTargetDelta;
}
if(_bounceEnabled)
{
// The new position is adjusted if out of boundary
newPosition = _autoScrollBrakingStartPosition + (newPosition - _autoScrollBrakingStartPosition) * brakingFactor;
}
else
{
// Don't let go out of boundary
Vec2 moveDelta = newPosition - getInnerContainerPosition();
Vec2 outOfBoundary = getHowMuchOutOfBoundary(moveDelta);
if (!fltEqualZero(outOfBoundary))
{
newPosition += outOfBoundary;
reachedEnd = true;
}
}
// Finish auto scroll if it ended
if(reachedEnd)
{
_autoScrolling = false;
dispatchEvent(SCROLLVIEW_EVENT_AUTOSCROLL_ENDED, EventType::AUTOSCROLL_ENDED);
}
moveInnerContainer(newPosition - getInnerContainerPosition(), reachedEnd);
}
bool ScrollView::startBounceBackIfNeeded()
{
if (!_bounceEnabled)
{
return false;
}
Vec2 bounceBackAmount = getHowMuchOutOfBoundary();
if(fltEqualZero(bounceBackAmount))
{
return false;
}
startAutoScroll(bounceBackAmount, BOUNCE_BACK_DURATION, true);
return true;
}
bool ScrollView::isOutOfBoundary()
{
return !fltEqualZero(getHowMuchOutOfBoundary());
}
