That thread was actually started by me :) In the reply, Sven pointed to pixmap-theme-engine as a way to implement transparent effects. That really helps. Pixmap-theme-engine works even on X since it can do client side processing when necessary.
However, this time my question was a little different, I were asking if we can support RGBA color value in drawing primitives rather than support alpha channel in image format. I believe that is out of scope of pixmap-theme-engine. That's the reason why I think I need to modify GDK gc part. Thanks anyway. On Wednesday 07 April 2004 22:15, Bill Hayden wrote: > On Wed, 2004-04-07 at 09:10, Xiong Huan wrote: > > Hi, > > > > I am considering leverage DirectFB's RGBA support and exposing it on > > GDK/GTK level. I noticed gdk-directfb uses standard GdkColor > > definition and > > > thus hides the underlying alpha-blending support. So I appended a new > > filed > > > "guchar alpha" in GdkColor structure, and in > > gdk_directfb_setup_for_drawing() > > > I assigned this value to "alpha" varialbe rather than used the > > original > > > hardcoded one(0xFF). I think this is a simple way to pass alpha value > > from > > > user to directfb and, at the same time, make as little change as > > possible. > > > Then I modified gtk_style_real_realize() in gtkstyle.c trying to test > > my > > > change. I hardcoded style->black.alpha to be 120, which is later > > passed to > > > gc_values.foreground. Then I run a simple gtk button application, > > thinking > > > its foregound color will be semi-transparent. However, there is no > > change at > > > all. > > > > I added some debug information in gdk_directfb_draw_lines() function > > and > > > notieced the alpha value(120 in my case) was really passed in it. But > > why it > > > has no effect at all? > > > > Am I missing somthing here? Can anyone throw some light on it? > > I believe this was just discussed a few weeks ago on the list, so you > may want to check the archives. My understanding is that gdk-DirectFB > only supports transparency at the "window" level. Now there is often > confusion about what is a window, since the meaning differs from > platform to platform and framework to framework. To make a long story > short: you are not assigning the transparency at a high-enough hierarchy > level. > > I'm just rehashing my understanding of what was discussed. I'm not a > GTK/DirectFB expert. -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe directfb-users" as subject.
