DrawingContext.PushOpacity Method (Double, AnimationClock)
Pushes the specified opacity setting onto the drawing context and applies the specified animation clock.
Assembly: PresentationCore (in PresentationCore.dll)
The opacity factor to apply to subsequent drawing commands. This factor is cumulative with previous PushOpacity operations.
The opacity is blended into all subsequent drawing commands until it is removed by the Pop command.
Available since 3.0