' Create a rectangle.
Dim myRectangle As New Rectangle()
myRectangle.Width = 100
myRectangle.Height = 100

' Load the image.
Dim theImage As New BitmapImage(New Uri("sampleImages\testImage.gif", UriKind.Relative))
Dim myImageBrush As New ImageBrush(theImage)
With myImageBrush
    .Viewbox = New Rect(0.5, 0.25, 0.25, 0.5)
    .ViewboxUnits = BrushMappingMode.RelativeToBoundingBox
    .Viewport = New Rect(0, 0, 0.25, 0.25)
    .ViewportUnits = BrushMappingMode.RelativeToBoundingBox
    .TileMode = TileMode.Tile
    .Stretch = Stretch.Fill
    .AlignmentX = AlignmentX.Center
    .AlignmentY = AlignmentY.Center
End With

' Use the ImageBrush to paint the rectangle's background.
myRectangle.Fill = myImageBrush