All elements in XAML including all brushes have an Opacity
attribute that defines the transparency of an element. The value of Opacity is
between 0 and 1. The value 0 means an element is fully-transparent and value 1
means an element is fully opaque. The default value of Opacity is 1.
The following code snippet creates a SolidColorBrush with
50% transparency. You can set the Opacity attribute of any brush using same
<SolidColorBrush Color="Blue" Opacity="0.5"/>
we set Opacity of code in 25 as following, the output that looks like Figure 33
will look like Figure 34.
<VisualBrush Viewport="0,0,0.25, 0.25" TileMode="Tile" Opacity="0.5">
The following code
snippet sets the Opacity property of a VisualBrush at run-time.
vBrush = new VisualBrush();
vBrush.Opacity = 0.50;
Figure 34. A rectangle with a transparent Visual brush in Tile mode
Good part is, this Opacity property not only is available for brushes but also for all elements in WPF and XAML. That means, you can create transparent Windows, Pages, Controls, or User Controls by simply setting this property.