TickerFuture _animateToInternal(float target, TimeSpan?duration = null, Curve curve = null)
{
curve = curve ?? Curves.linear;
TimeSpan?simulationDuration = duration;
if (simulationDuration == null)
{
D.assert(() => {
if ((this.duration == null && _direction == _AnimationDirection.reverse && reverseDuration == null) ||
(this.duration == null && _direction == _AnimationDirection.forward))
{
throw new UIWidgetsError(
"AnimationController.animateTo() called with no explicit Duration and no default duration or reverseDuration.\n" +
"Either the \"duration\" argument to the animateTo() method should be provided, or the " +
"\"duration\" and/or \"reverseDuration\" property should be set, either in the constructor or later, before " +
"calling the animateTo() function."
);
}
return(true);
});
float range = upperBound - lowerBound;
float remainingFraction = range.isFinite() ? (target - _value).abs() / range : 1.0f;
TimeSpan directionDuration = (_direction == _AnimationDirection.reverse && reverseDuration != null)
? reverseDuration.Value
: this.duration.Value;
simulationDuration = TimeSpan.FromTicks((long)(directionDuration.Ticks * remainingFraction));
}
else if (target == value)
{
simulationDuration = TimeSpan.Zero;
}
stop();
if (simulationDuration == TimeSpan.Zero)
{
if (_value != target)
{
_value = target.clamp(lowerBound, upperBound);
notifyListeners();
}
_status = (_direction == _AnimationDirection.forward)
? AnimationStatus.completed
: AnimationStatus.dismissed;
_checkStatusChanged();
return(TickerFuture.complete());
}
D.assert(simulationDuration > TimeSpan.Zero);
D.assert(!isAnimating);
return(_startSimulation(
new _InterpolationSimulation(_value, target, simulationDuration.Value, curve)));
}
void _animate()
{
if (_animationController.isAnimating)
{
return;
}
bool wasHeldDown = _buttonHeldDown;
TickerFuture ticker = _buttonHeldDown
? _animationController.animateTo(1.0f, duration: kFadeOutDuration)
: _animationController.animateTo(0.0f, duration: kFadeInDuration);
ticker.then(_ => {
if (mounted && wasHeldDown != _buttonHeldDown)
{
_animate();
}
});
}
