Pen Opacity

hi,

is there anyway to change the opacity of lines and stuff [i guess it would be some sort of setting with the CPen thing..] that you draw onto a CPaintDC?

for instance if you are drawing lines on top of an image you are displaying, is there a simple way to change the amount you can see through the lines and onto the image?

thanks.

There is not an attribute in the normal GDI interface for opacity, there may be in GDI+, but I don't have access to a system with that loaded.

One way to simulate this may be by drawing a long thin rectangle linking the start and end points of the "line" and fill the rectangle with a pattern that combines your chosen colour and "transparent" in some combination. Never tried it, but it may look okay.

yeah, i had thought of an answer like that, but that would require overhead in terms of calculating the 'colour' of each pixel in each line... which is OK, for static stuff but potentially crippling if there are many lines and you are moving the images and lines...

thanks for the suggestion though.

anybody know anything about MultipleLayerWindows?

could this be a possible solution to the problem?