WPF: How to Erase somthing in canvas?

Hello, I'm trying to make a drawing board tha support adding shapes and images. for pencil I use this code and I don't think that there is a way to erase it but just trying:

            Dim lin As New Line
            lin.Stroke = New SolidColorBrush(Color.FromArgb(100, 255, 0, 0))
            lin.StrokeThickness = 5
'lastpnt is the LastPoint added to continue the drawing and it will be null on mouse_up Event
            If Not lastpnt = Nothing Then
                lin.X1 = lastpnt.X
                lin.Y1 = lastpnt.Y
                lin.X2 = position.X
                lin.Y2 = position.Y
                lastpnt.X = position.X
                lastpnt.Y = position.Y
            Else
                lin.X1 = position.X
                lin.Y1 = position.Y
                lin.X2 = position.X
                lin.Y2 = position.Y
                lastpnt.X = position.X
                lastpnt.Y = position.Y
            End If
            Canvas1.Children.Add(lin)

I can make the eraser the same as background color but what if the back color was transparent or was an image ????
I will now read the 'InkCanvas' source code trying to find another way to draw and erase.

Note : I didn't use inkcanvas due to no support adding images above the ink drawing and then drawing on image (I don't know how to explain but its like ink and Images zOrder)

Tags: WPF, Canvas