CompositionMaskBrush Class

Definition

Namespace:

Microsoft.UI.Composition

Paints a SpriteVisual with a CompositionBrush with an opacity mask applied to it. The source of the opacity mask can be any CompositionBrush of type CompositionColorBrush, CompositionLinearGradientBrush, CompositionSurfaceBrush, CompositionEffectBrush or a CompositionNineGridBrush. The opacity mask must be specified as a CompositionSurfaceBrush.

public ref class CompositionMaskBrush sealed : CompositionBrush

/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
/// [Windows.Foundation.Metadata.ContractVersion(Microsoft.Foundation.WindowsAppSDKContract, 65536)]
class CompositionMaskBrush final : CompositionBrush

[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
[Windows.Foundation.Metadata.ContractVersion(typeof(Microsoft.Foundation.WindowsAppSDKContract), 65536)]
public sealed class CompositionMaskBrush : CompositionBrush

Public NotInheritable Class CompositionMaskBrush
Inherits CompositionBrush

Inheritance

Object Platform::Object IInspectable CompositionObject CompositionBrush CompositionMaskBrush

Attributes

ContractVersionAttribute MarshalingBehaviorAttribute ThreadingAttribute

Examples

Apply a star-shaped mask to an image.

private SpriteVisual CreateCircleImage(ICompositionSurface myImageSurface, ICompositionSurface myStarMaskSurface) 
{ 
  // Create SurfaceBrush with image surface and specify stretch and alignment 
  CompositionSurfaceBrush imageBrush = _compositor.CreateSurfaceBrush(myImageSurface); 
  imageBrush.HorizontalAlignmentRatio = 0.5f; 
  imageBrush.VerticalAlignmentRatio = 0.5f; 
  imageBrush.Stretch = CompositionStretch.UniformToFill; 

  // Create surface brush with opacity mask surface and specify stretch and alignment 
  CompositionSurfaceBrush starMaskBrush = _compositor.CreateSurfaceBrush(myStarMaskSurface); 
  starMaskBrush.Stretch = CompositionStretch.Uniform; 

  // SpriteVisual to be painted with masked content 
  SpriteVisual imageVisual = _compositor.CreateSpriteVisual(); 
  imageVisual.Size = new Vector2(200, 200); 

  // Create MaskBrush 
  CompositionMaskBrush maskBrush = _compositor.CreateMaskBrush(); 
  maskBrush.Source = imageBrush; // Set source to content that is to be masked 
  maskBrush.Mask = starMaskBrush; // Set mask to content that is the opacity mask 

  imageVisual.Brush = maskBrush; // Paint SpriteVisual with MaskBrush 

  return imageVisual;           
} 

Applying an opacity mask to solid color fill to create a shape; animate the transform property on the opacity mask CompositionSurfaceBrush to create a color bloom animation

private void CreateCircleMaskSprite(ICompositionSurface myCircleMaskSurface, ICompositionSurface myImageSurface)
{
  // SpriteVisual to be painted by MaskBrush
  _circleVisual = _compositor.CreateSpriteVisual();
  _circleVisual.Size = MyContainerGrid.RenderSize.ToVector2();

  // SurfaceBrush w/ image as MaskBrush.Source
  CompositionSurfaceBrush imageBrush = _compositor.CreateSurfaceBrush(myImageSurface);
  imageBrush.Stretch = CompositionStretch.UniformToFill;

  // SurfaceBrush w/ opacity mask surface as MaskBrush.Mask
  CompositionSurfaceBrush circleBrush = _compositor.CreateSurfaceBrush(myCircleMaskSurface);

  // Specify stretch and transform properties to scale and position brush for initial state
  circleBrush.Stretch = CompositionStretch.Uniform;
  circleBrush.CenterPoint = _circleVisual.Size / 2;
  circleBrush.Scale = new Vector2(0.5f);

  // Create MaskBrush
  CompositionMaskBrush maskBrush = _compositor.CreateMaskBrush();
  maskBrush.Source = imageBrush;
  maskBrush.Mask = circleBrush;
  _circleVisual.Brush = maskBrush;

  // Set SpriteVisual as child of XAML Grid
  ElementCompositionPreview.SetElementChildVisual(MyContainerGrid, _circleVisual);
}

private void BloomAnimation()
{
  // Create KeyFrame Animation to target Scale transform on SurfaceBrush 
  Vector2KeyFrameAnimation scaleAnimation = _compositor.CreateVector2KeyFrameAnimation();
  scaleAnimation.InsertKeyFrame(1.0f, new Vector2(2));
  scaleAnimation.Duration = TimeSpan.FromMilliseconds(500);

  var maskBrush = (CompositionMaskBrush)_circleVisual.Brush;
  var surfaceBrush = (CompositionSurfaceBrush) maskBrush.Mask;

  // Animate the Scale on the circle opacity mask
  surfaceBrush.StartAnimation("Scale", scaleAnimation);      
}

Applying a rounded rectangle mask to create a solid color rounded rectangle whose corner radius does not increase upon resizing (use CompositionNineGridBrush as input to a CompositionMaskBrush ).

private SpriteVisual CreateMaskedRoundedRectVisual(ICompositionSurface myRoundedRectMaskSurface)
{
  // ColorBrush to be set as MaskBrush.Source
  CompositionColorBrush colorBrush = _compositor.CreateColorBrush(Colors.Blue);

  // SurfaceBrush w/ opacity mask surface
  CompositionSurfaceBrush roundedRectBrush = _compositor.CreateSurfaceBrush(myRoundedRectMaskSurface);
  roundedRectBrush.Stretch = CompositionStretch.Fill; // stretch for center of nine-grid

  // NineGridBrush w/ insets on opacity mask surface
  CompositionNineGridBrush ninegridBrush = _compositor.CreateNineGridBrush();
  ninegridBrush.Source = roundedRectBrush;
  ninegridBrush.SetInsets(_cornerRadius); // the radius, in pixels, of the corner as specified on my opacity mask surface 

  // Create MaskBrush
  CompositionMaskBrush maskBrush = _compositor.CreateMaskBrush();
  maskBrush.Source = colorBrush;
  maskBrush.Mask = ninegridBrush;

  // Paint SpriteVisual with MaskBrush
  SpriteVisual sprite = _compositor.CreateSpriteVisual();
  sprite.Size = new Vector2(300, 200);
  sprite.Brush = maskBrush;
  return sprite;

}

Remarks

CompositionMaskBrush can not be set as the source parameter to a CompositionEffectBrush. If you wish to apply an IGraphicsEffect to your masked content, use a CompositionEffectBrush with the Composite effect instead.

Properties

Comment	A string to associate with the CompositionObject. (Inherited from CompositionObject)
Compositor	The Compositor used to create this CompositionObject. (Inherited from CompositionObject)
DispatcherQueue	Gets the DispatcherQueue for the CompositionObject. (Inherited from CompositionObject)
ImplicitAnimations	The collection of implicit animations attached to this object. (Inherited from CompositionObject)
Mask	A brush that contains the opacity mask with which the Source brush's content is to be masked. Can be of type CompositionSurfaceBrush or CompositionNineGridBrush.
Properties	The collection of properties associated with the CompositionObject. (Inherited from CompositionObject)
Source	A brush whose content is to be masked by the opacity mask. Can be of type CompositionSurfaceBrush, CompositionColorBrush, or CompositionNineGridBrush.

Methods

Close()	Closes the CompositionObject and releases system resources. (Inherited from CompositionObject)
Dispose()	Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources. (Inherited from CompositionObject)
PopulatePropertyInfo(String, AnimationPropertyInfo)	Defines a property that can be animated. (Inherited from CompositionObject)
StartAnimation(String, CompositionAnimation, AnimationController)	Connects an animation with the specified property of the object and starts the animation. (Inherited from CompositionObject)
StartAnimation(String, CompositionAnimation)	Connects an animation with the specified property of the object and starts the animation. (Inherited from CompositionObject)
StartAnimationGroup(ICompositionAnimationBase)	Starts an animation group. The StartAnimationGroup method on CompositionObject lets you start CompositionAnimationGroup. All the animations in the group will be started at the same time on the object. (Inherited from CompositionObject)
StopAnimation(String)	Disconnects an animation from the specified property and stops the animation. (Inherited from CompositionObject)
StopAnimationGroup(ICompositionAnimationBase)	Stops an animation group. (Inherited from CompositionObject)
TryGetAnimationController(String)	Returns an AnimationController for the animation running on the specified property. (Inherited from CompositionObject)

See also

• CompositionBrush
• IClosable