Mask / ALpha trouble in iOS

Targets iOS
4

I guess I can distill it down a bit more. Here’s a function that will take a picture and create an appropriate mask:

Private Function createMaskPicture(source as Picture) As Picture
  if source = nil then Return nil
  
  var result as new Picture( source.Width, source.Height )
  result.HorizontalResolution = source.HorizontalResolution
  result.VerticalResolution = source.VerticalResolution
  var g as Graphics = result.Graphics
  g.ScaleX = source.Graphics.scaleX
  g.ScaleY = source.Graphics.scaleY
  
  Return result
End Function

Then used likes this:

Sub Paint(g As Graphics) Handles Paint
  var p as Picture = new Picture( avatar.Width, avatar.Height )
  p.Graphics.DrawPicture( avatar, 0, 0 )
  
  var mask as Picture = createMaskPicture( p )
  if mask <> nil then
    var m as Graphics = mask.Graphics
    m.DrawingColor = &cffffff
    m.FillRectangle( 0, 0, m.Width + 10, g.Height )
    m.DrawingColor = &c000000
    m.FillOval( 0, 0, m.Width, m.Height )
  
    p.ApplyMask( mask )
  end if
  
  g.DrawPicture( p, 0, 0 )
End Sub