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[REBOL] Re: alpha image blending...

From: roland:hadinger:arcor at: 23-Jul-2003 3:10

Warning: actually I've STILL got no good grasp of how certain things are done with REBOL view, but I couldn't resist answering :/ A simple test which just displays two overlapping 32 bit RGBA images taken from the PNG web site (image download ~ 500 k): view f: layout [ origin 0x0 backcolor white at 0x0 image at 0x0 image ] If this displays what it says on your system (a window with a bright background, magnolias and an owl in the foreground), then there is alpha channel support. imageC: to-image f converts f to an image. In doing this, you get an image without alpha channel data , however (or at least I think so, correct me if I'm wrong here). So depending on what you want to do besides merging images, you might have to manipulate the alpha channel data with 'pick and 'poke (-> For example, to clear the alpha channel of an image: clear-alpha: func [i [image!] /local n] [ repeat n i/size/x * i/size/y [poke i n * pick i n] i ]