public CompositionImage()
{
this.DefaultStyleKey = typeof(CompositionImage);
this.Background = new SolidColorBrush(Colors.Transparent);
this._stretchMode = CompositionStretch.Uniform;
this.Loading += CompImage_Loading;
this.Unloaded += CompImage_Unloaded;
this.SizeChanged += CompImage_SizeChanged;
_compositor = ElementCompositionPreview.GetElementVisual(this).Compositor;
// Intialize the statics as needed
if (!_staticsInitialized)
{
_defaultPlaceholderBrush = _compositor.CreateColorBrush(Colors.DarkGray);
TimeSpan duration = TimeSpan.FromMilliseconds(1000);
_fadeOutAnimation = _compositor.CreateScalarKeyFrameAnimation();
_fadeOutAnimation.InsertKeyFrame(0, 1);
_fadeOutAnimation.InsertKeyFrame(1, 0);
_fadeOutAnimation.Duration = duration;
_scaleAnimation = _compositor.CreateVector2KeyFrameAnimation();
_scaleAnimation.InsertKeyFrame(0, new Vector2(1.25f, 1.25f));
_scaleAnimation.InsertKeyFrame(1, new Vector2(1, 1));
_scaleAnimation.Duration = duration;
_staticsInitialized = true;
}
// Initialize the surface loader if needed
if (!SurfaceLoader.IsInitialized)
{
SurfaceLoader.Initialize(ElementCompositionPreview.GetElementVisual(this).Compositor);
}
_placeholderDelay = TimeSpan.FromMilliseconds(50);
_surfaceBrush = _compositor.CreateSurfaceBrush(null);
}
private async void LoadSurface()
{
// If we're clearing out the content, return
if (_uri == null)
{
ReleaseSurface();
return;
}
try
{
// Start a timer to enable the placeholder image if requested
if (_surface == null && _placeholderDelay >= TimeSpan.Zero)
{
_timer = new DispatcherTimer();
_timer.Interval = _placeholderDelay;
_timer.Tick += Timer_Tick;
_timer.Start();
}
// Load the image asynchronously
CompositionDrawingSurface surface = await SurfaceLoader.LoadFromUri(_uri, Size.Empty, _loadEffectDelegate);
if (_surface != null)
{
ReleaseSurface();
}
_surface = surface;
// The surface has changed, so we need to re-measure with the new surface dimensions
InvalidateMeasure();
// Async operations may take a while. If we've unloaded, return now.
if (_unloaded)
{
ReleaseSurface();
return;
}
// Update the brush
UpdateBrush();
// Success, fire the Opened event
if (ImageOpened != null)
{
ImageOpened(this, null);
}
//
// If we created the loading placeholder, now that the image has loaded
// cross-fade it out.
//
if (_sprite != null && _sprite.Children.Count > 0)
{
Debug.Assert(_timer == null);
StartCrossFade();
}
else if (_timer != null)
{
// We didn't end up loading the placeholder, so just stop the timer
_timer.Stop();
_timer = null;
}
}
catch (FileNotFoundException)
{
if (ImageFailed != null)
{
ImageFailed(this, null);
}
}
}