private async void InitComposition()
{
// Store our Compositor and create our ImageLoader.
_compositor = ElementCompositionPreview.GetElementVisual(this).Compositor;
_imageLoader = ImageLoaderFactory.CreateImageLoader(_compositor);
// Setup our effect definition. First is the CompositeEffect that will take
// our sources and produce the intersection of the images (because we selected
// the DestinationIn mode for the effect). Next we take our CompositeEffect
// and make it the source of our next effect, the InvertEffect. This will take
// the intersection image and invert the colors. Finally we take that combined
// effect and put it through a HueRotationEffect, were we can adjust the colors
// using the Angle property (which we will animate below).
IGraphicsEffect graphicsEffect = new HueRotationEffect
{
Name = "hueEffect",
Angle = 0.0f,
Source = new InvertEffect
{
Source = new CompositeEffect
{
Mode = Microsoft.Graphics.Canvas.CanvasComposite.DestinationIn,
Sources =
{
new CompositionEffectSourceParameter("image"),
new CompositionEffectSourceParameter("mask")
}
}
}
};
// Create our effect factory using the effect definition and mark the Angle
// property as adjustable/animatable.
_effectFactory = _compositor.CreateEffectFactory(graphicsEffect, new string[] { "hueEffect.Angle" });
// Create MangedSurfaces for both our base image and the mask we'll be using.
// The mask is a transparent image with a white circle in the middle. This is
// important since the CompositeEffect will use just the circle for the
// intersectionsince the rest is transparent.
var managedImageSurface = await _imageLoader.CreateManagedSurfaceFromUriAsync(new Uri("ms-appx:///Assets/tripphoto1.jpg"));
var managedMaskSurface = await _imageLoader.CreateManagedSurfaceFromUriAsync(new Uri("ms-appx:///Assets/CircleMask.png"));
// Create brushes from our surfaces.
var imageBrush = _compositor.CreateSurfaceBrush(managedImageSurface.Surface);
var maskBrush = _compositor.CreateSurfaceBrush(managedMaskSurface.Surface);
// Create an setup our effect brush.Assign both the base image and mask image
// brushes as source parameters in the effect (with the same names we used in
// the effect definition). If we wanted, we could create many effect brushes
// and use different images in all of them.
var effectBrush = _effectFactory.CreateBrush();
effectBrush.SetSourceParameter("image", imageBrush);
effectBrush.SetSourceParameter("mask", maskBrush);
// All that's left is to create a visual, assign the effect brush to the Brush
// property, and attach it into the tree...
var visual = _compositor.CreateSpriteVisual();
visual.Size = managedImageSurface.Size.ToVector2();
visual.Offset = new Vector3(50, 50, 0);
visual.Brush = effectBrush;
ElementCompositionPreview.SetElementChildVisual(this, visual);
// ... but wait! There's more! We're going to animate the Angle property
// to get a really trippy color effect on our masked inverted image.
AnimateEffect(effectBrush);
}