/// <summary>
/// Adds the specified transition provider to the supported ones.
/// </summary>
/// <param name="provider">
/// The <see cref="IVisualTransitionProvider"/> to be added to the providers
/// which are used by the <see cref="ExtendedVisualStateManager"/>.
/// </param>
public static void AddProvider(IVisualTransitionProvider provider)
{
if (provider != null)
{
_transitionProviders.Add(provider);
}
}
private static bool TryFindRegisteredProviderForTimeline(
Timeline timeline, out IVisualTransitionProvider result)
{
// Go through the list from behind to allow overwriting of the standard providers.
for (int i = _transitionProviders.Count - 1; i >= 0; i--)
{
IVisualTransitionProvider currentProvider = _transitionProviders[i];
if (currentProvider.SupportsTimeline(timeline))
{
result = currentProvider;
return(true);
}
}
result = null;
return(false);
}
/// <summary>
/// Tries to return a registered <see cref="IVisualTransitionProvider"/> which supports
/// the specified <paramref name="timeline"/>.
/// If a provider was found, this method returns <c>true</c> and stores the provider
/// in the <paramref name="result"/> parameter.
/// If none was found, this method returns <c>false</c> and <paramref name="result"/>
/// is set to <c>null</c>.
/// </summary>
/// <param name="timeline">
/// The <see cref="Timeline"/>.
/// </param>
/// <param name="result">
/// An <see cref="IVisualTransitionProvider"/> which will hold the result of this method.
/// </param>
/// <returns>
/// A <see cref="Boolean"/> indicating whether getting a provider succeeded;
/// </returns>
public static bool TryGetProviderForTimeline(Timeline timeline, out IVisualTransitionProvider result)
{
if (timeline == null)
{
throw new ArgumentNullException(nameof(timeline));
}
// Allow timelines to implement the interface themselves.
// This allows them to generate the transitions on their own, without an external class.
// This is, for example, used by the FromToByAnimationBase, which automatically provides
// custom transitions for each animation that derives from it.
if (timeline is IVisualTransitionProvider selfAwareTimelineProvider &&
selfAwareTimelineProvider.SupportsTimeline(timeline))
{
result = selfAwareTimelineProvider;
return(true);
}
// If the timeline doesn't self provide the values, check for a registered provider.
return(TryFindRegisteredProviderForTimeline(timeline, out result));
}