How to let gdi/gid+ object (pen\brush\rect\region etc.) semi-transparent?

问题

I want draw multi layer in DC. each layer have some gdi/gdi+ object and semi-transparent with the underlayer.

回答1:

you need to use the ARGB system for coloring. A represents transparency, it takes a value between 0 and 255. a value of 125 is semi transparant

回答2:

Using the function SetROP2 with the argument R2_MASKPEN is a very simple way to get a transparent pen effect.

来源：https://stackoverflow.com/questions/4261536/how-to-let-gdi-gid-object-pen-brush-rect-region-etc-semi-transparent