static void AnimateKineticInternal(IAnimatable self, string name, Func <double, double, bool> callback, double velocity, double drag, Action?finished = null)
{
var key = new AnimatableKey(self, name);
AbortKinetic(key);
double sign = velocity / Math.Abs(velocity);
velocity = Math.Abs(velocity);
int tick = Ticker.Default.Insert(step =>
{
long ms = step;
velocity -= drag * ms;
velocity = Math.Max(0, velocity);
var result = false;
if (velocity > 0)
{
result = callback(sign * velocity * ms, velocity);
}
if (!result)
{
finished?.Invoke();
s_kinetics.Remove(key);
}
return(result);
});
s_kinetics[key] = tick;
}
static void AnimateInternal <T>(IAnimatable self, string name, Func <double, T> transform, Action <T> callback,
uint rate, uint length, Easing?easing, Action <T, bool>?finished, Func <bool>?repeat)
{
var key = new AnimatableKey(self, name);
AbortAnimation(key);
Action <double> step = f => callback(transform(f));
Action <double, bool>?final = null;
if (finished != null)
{
final = (f, b) => finished(transform(f), b);
}
var tweener = new Tweener(length, rate);
tweener.Handle = key;
tweener.ValueUpdated += HandleTweenerUpdated;
tweener.Finished += HandleTweenerFinished;
var info = new Info(rate, length, easing ?? Easing.Linear, tweener, step, new WeakReference <IAnimatable>(self));
info.Finished = final;
info.Repeat = repeat;
s_animations[key] = info;
info.Callback(0.0f);
tweener.Start();
}
static void AbortKinetic(AnimatableKey key)
{
if (!s_kinetics.ContainsKey(key))
{
return;
}
Ticker.Default.Remove(s_kinetics[key]);
s_kinetics.Remove(key);
}
public static bool AbortAnimation(this IAnimatable self, string handle)
{
var key = new AnimatableKey(self, handle);
if (!s_animations.ContainsKey(key) && !s_kinetics.ContainsKey(key))
{
return(false);
}
Action abort = () =>
{
AbortAnimation(key);
AbortKinetic(key);
};
DoAction(self, abort);
return(true);
}
protected bool Equals(AnimatableKey other)
{
if (!string.Equals(Handle, other.Handle))
{
return(false);
}
IAnimatable?thisAnimatable;
if (!Animatable.TryGetTarget(out thisAnimatable))
{
return(false);
}
IAnimatable?thatAnimatable;
if (!other.Animatable.TryGetTarget(out thatAnimatable))
{
return(false);
}
return(Equals(thisAnimatable, thatAnimatable));
}
static void AbortAnimation(AnimatableKey key)
{
// If multiple animations on the same view with the same name (IOW, the same AnimatableKey) are invoked
// asynchronously (e.g., from the `[Animate]To` methods in `ViewExtensions`), it's possible to get into
// a situation where after invoking the `Finished` handler below `s_animations` will have a new `Info`
// object in it with the same AnimatableKey. We need to continue cancelling animations until that is no
// longer the case; thus, the `while` loop.
// If we don't cancel all of the animations popping in with this key, `AnimateInternal` will overwrite one
// of them with the new `Info` object, and the overwritten animation will never complete; any `await` for
// it will never return.
while (s_animations.ContainsKey(key))
{
Info info = s_animations[key];
s_animations.Remove(key);
info.Tweener.ValueUpdated -= HandleTweenerUpdated;
info.Tweener.Finished -= HandleTweenerFinished;
info.Tweener.Stop();
info.Finished?.Invoke(1.0f, true);
}
}
public static bool AnimationIsRunning(this IAnimatable self, string handle)
{
var key = new AnimatableKey(self, handle);
return(s_animations.ContainsKey(key));
}