private async void UpdateSource()
{
if (_canvas == null || _isAnimating || _lastSource == Source) // is animating or no change
{
return;
}
_isAnimating = true;
var currentSource = Source;
if (_lastSource == null)
{
ForegroundImage.Opacity = 0.0;
var success = SingleEvent.WaitForEventAsync(ForegroundImage,
(image, handler) => image.ImageOpened += handler,
(image, handler) => image.ImageOpened -= handler);
var failure = SingleEvent.WaitForEventAsync(ForegroundImage,
(image, handler) => image.ImageFailed += handler,
(image, handler) => image.ImageFailed -= handler);
ImageHelper.SetSource(ForegroundImage, currentSource);
var task = await Task.WhenAny(new[] { success, failure });
if (task == success)
{
await Fading.FadeInAsync(ForegroundImage, FadingDuration, FadingOpacity);
}
// TODO Deregister not called event
}
else if (currentSource != null) // exchange images
{
BackgroundImage.Opacity = 0.0;
var success = SingleEvent.WaitForEventAsync(BackgroundImage,
(image, handler) => image.ImageOpened += handler,
(image, handler) => image.ImageOpened -= handler);
var failure = SingleEvent.WaitForEventAsync(BackgroundImage,
(image, handler) => image.ImageFailed += handler,
(image, handler) => image.ImageFailed -= handler);
ImageHelper.SetSource(BackgroundImage, currentSource);
if (!WaitForNextImage)
{
Fading.FadeOutAsync(ForegroundImage, FadingDuration);
}
var task = await Task.WhenAny(new[] { success, failure });
if (task == success)
{
if (WaitForNextImage)
{
await Task.WhenAll(new[]
{
Fading.FadeInAsync(BackgroundImage, FadingDuration, FadingOpacity),
Fading.FadeOutAsync(ForegroundImage, FadingDuration)
});
}
else
{
await Fading.FadeInAsync(BackgroundImage, FadingDuration, FadingOpacity);
}
ImageHelper.SetSource(ForegroundImage, null);
// reverse image order
var fore = ForegroundImage;
var back = BackgroundImage;
_canvas.Children.Clear();
_canvas.Children.Add(fore);
_canvas.Children.Add(back);
}
else
{
await Fading.FadeOutAsync(ForegroundImage, FadingDuration);
}
}
else
{
BackgroundImage.Opacity = 0.0;
await Fading.FadeOutAsync(ForegroundImage, FadingDuration);
}
_isAnimating = false;
_lastSource = currentSource;
UpdateSource();
}