Returns the opacity of the Visual.
Assembly: PresentationCore (in PresentationCore.dll)
The value of the opacity is expressed as a value between 0 and 1. A value of 0 indicates that the element is completely transparent, while a value of 1 indicates that the element is completely opaque. A value of 0.5 indicates that the element is 50 percent opaque. Values less than 0 are treated as 0, and values greater than 1 are treated as 1.