Custom pen mode in delphi

Does anyone know how it is possible to create a new 开发者_如何学Gopen mode so that I can use it in this way: shape1.pen.mode:=pmCustom; Then I'm gonna define what color each pixel must have. For example, I'd create a pen mode that paints blue when behind the specified pixel is a light colored one; and paints white when the behind pixel is dark.

Thanks in advance

The VCL property TPen.Mode maps onto the GDI function SetROP2. This has no option for what you describe and so I believe that what you ask is not possible.

To achieve the sort of effect you are looking for is likely going to require some hand-crafting.