/// <summary>
/// Transitions out of the state. Calls to <see cref="TransitionIn"/> and <see cref="TransitionOut"/> are synchronized
/// and only one will be executed at a time, the rest will be blocked and executed in FIFO order.
/// </summary>
/// <paramref name="useTransitions">If true, use defined storyboard animations in the transition</paramref>
public override async Task TransitionOut(VisualTransitionType type, bool useTransitions = true)
{
// If it's a transition to self and the transition out should be omitted return
if (type == VisualTransitionType.ToTheSameSetup &&
!(await GetRepeatedTransition()).HasFlag(RepeatedTransitionBehavior.TransitionOut))
{
return;
}
// Get into the semaphore
await _TransitionSemaphore.WaitAsync();
// Reset the temporary setters
DispatcherHelpers.RunAsync(() => TemporarySetters.ForEach((x) => x.Reset()));
if (useTransitions)
{
bool sbDefined = false;
// Get on the UI thread
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
// If the storyboard is defined
if (TransitionOutStoryboard.WillComplete())
{
sbDefined = true;
// Run it
TransitionOutStoryboard?.Begin();
}
});
// If the UI thread task determined that storyboard was defined, start a task that will wait for the storyboard to finish
if (sbDefined)
{
await Task.Run(() => _WaitForStoryboardToFinish.WaitOne());
}
}
// Transition finished; Release the semaphore
_TransitionSemaphore.Release();
}
/// <summary>
/// Transitions out of the state. Cancels transition in operation (if it was happening).
/// </summary>
/// <param name="useTransitions"></param>
/// <returns></returns>
public override async Task TransitionOut(VisualTransitionType type, bool useTransitions = true)
{
// If there's already a transition out going on and we're not supposed to restart it, just return
if (type == VisualTransitionType.ToTheSameSetup &&
!(await GetRepeatedTransition()).HasFlag(RepeatedTransitionBehavior.TransitionOut))
{
return;
}
// If the CancellationTokenSource from the previous transition call is still alive cancel it
_Cancellation?.Cancel();
// Create a new source for ourselves
var cancellation = new CancellationTokenSource();
// And assign it to the class-wide variable
_Cancellation = cancellation;
// Reset the temporary setters
DispatcherHelpers.RunAsync(() => TemporarySetters.ForEach((x) => x.Reset()));
if (useTransitions)
{
bool sbDefined = false;
// Get on the UI thread
await DispatcherHelpers.RunAsync(() =>
{
// If the storyboard is defined
if (TransitionOutStoryboard.WillComplete())
{
// signal it
sbDefined = true;
// Pause the transition in storyboard
TransitionInStoryboard?.Pause();
// Run the transition out storyboard
TransitionOutStoryboard?.Begin();
}
});
// If the UI thread task determined that storyboard was defined, start a task that will wait for the storyboard to finish
if (sbDefined)
{
// Wait either for cancellation or storyboard to finish so that this Task doesn't end before the operations
// are completed
if (await Task.Run(() => WaitHandle.WaitAny(new[] { cancellation.Token.WaitHandle, _WaitForStoryboard }) == 1))
{
// If we weren't cancelled remove the reference to the _Cancellation, otherwise the one cancelling
// will provide their own CancellationTokenSource therefore removing the reference to ours
_Cancellation = null;
}
}
else if (!cancellation.IsCancellationRequested)
{
// If our cancellation was not removed by another call, remove the reference to it
_Cancellation = null;
}
}
cancellation.Dispose();
}