Ummm, actually this is conceptually wrong, because the images are not stored in memory using the format of the file, so for any image format you can simply set TRasterImage.PixelFormat to pf32bit to allocate a 8-bit channel for Alpha while in memory.
The problem is that I can't find routines to draw to this Alpha channel. It seams it isn't yet implemented, and because Delphi doesn't implement it we also need to think of an interface for this. Also, 32-bit Bitmaps support transparency: http://en.wikipedia.org/wiki/Comparison_of_graphics_file_formats The separate classes for each format only implement load/saving to stream/file ... the actual in memory format options is common. > To do what you want you can use TPortableNetworkGraphic (for PNG format) in > place of TBitmap. It's nearly the same interface (common parent component) > with PNG format abilities in more (such as alpha channel). Not really. Have you ever checked the declaration of TPortableNetworkGraphic? It doesn't implement anything except load/saving to stream/file I took a look at the interface from TPNGObject (from TPNGImage project) which was bought by Delphi and it seams only to offer a scanline for the alpha channel. -- Felipe Monteiro de Carvalho -- _______________________________________________ Lazarus mailing list [email protected] http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
