Hi! Thanks a lot for the information. I guess I will have to play with it to really figure it out. I think that what I want is really just color-keying... Am I right in assuming that color keying will usually be hardware accellerated - since most video cards support a color keyed overlay plane, while alpha-blending will not be accellerated, since alpha-overlays are not supported by most hardware? Or is it a lot more complicated than that? I'm going to have to get into the code more deeply to answer most of my questions I think, but it is slow going... Thanks! Richard Unger
________________________________ From: Denis Oliver Kropp [mailto:[EMAIL PROTECTED] Sent: Tue 9/13/2005 12:14 PM To: Unger Richard Cc: [email protected] Subject: Re: [directfb-users] DFB Questions: Understanding Window Translucency Quoting Unger Richard: > I can set a window's opacity using SetOpacity() -> I assume this is also > what is mapped to <meta>+<alt>+mouse Yes. > Docs: "Set it to "0" to hide a window. Setting it to "0xFF" makes the > window opaque if it has no alpha channel." > I can also set a ColorKey for a window using SetColorKey() > Docs: "If a pixel of the window matches this color the underlying window > or the background is visible at this point." > > How do these two settings affect each other? First color keying is applied, then the remaining pixels are blended. > I observe that in the default setup, when I change a windows opacity, it > is the black areas of the window that become most transparent. The white > areas remain mostly opaque. Why is this? It might look like that, but all colors are equally blended. If you have a bright background you might find it the other way around. > Is there a way to set up the following modes? > > A) Window blending based only on color key - ie all blue (#0000ff) areas > of a window are 100% transparent, all non-blue areas are 100% opaque. That's color keying only, i.e. create the window and set DWOP_COLORKEYING using SetOptions(). > B) Window blending based only on alpha value of window pixels - window > is blended according to values of the alpha channel. (Would this require > the window to use an ARGB drawing surface?). That's blending only, i.e. create the window with the DWCAPS_ALPHACHANNEL capability in the window description's "caps" field. Make sure you set the DWDESC_CAPS flag in "flags". Any format with an alpha channel can be used, but the default is ARGB. If you want another format, just set the DWDESC_PIXELFORMAT flag and the "pixelformat" field. -- Best regards, Denis Oliver Kropp .------------------------------------------. | DirectFB - Hardware accelerated graphics | | http://www.directfb.org/ | "------------------------------------------" _______________________________________________ directfb-users mailing list [email protected] http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
