For those who want to check it out with a reference to vbRichClient5 (offering antialiasing on the Clip-Regions,
and working on any Win-OS), here's replacement code for Form1 of dilettantes WIA-demo.

Code:
Option Explicit

Private CC As cCairoContext

Private Sub Form_Load()
  Cairo.ImageList.AddImage "BackDrop", LoadResData("BACKDROP", "PNG")
  Cairo.ImageList.AddImage "Curtain", LoadResData("CURTAIN", "PNG")
  
  ScaleMode = vbPixels
  Set CC = Cairo.CreateSurface(ScaleWidth, ScaleHeight).CreateContext
  Redraw
  Picture1.Visible = False '<- we don't need that
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
  Redraw X, Y, 100
End Sub

Private Sub Redraw(Optional ByVal xc&, Optional ByVal yc&, Optional ByVal Radius&)
  CC.RenderSurfaceContent "Curtain", 0, 0
  CC.ARC xc, yc, Radius
  CC.Clip
    CC.RenderSurfaceContent "BackDrop", 0, 0
  CC.ResetClip
  Set Picture = CC.Surface.Picture
End Sub

Private Sub Form_Terminate()
  New_c.CleanupRichClientDll
End Sub
Producing this:


Olaf