alan@cogswell.Jpl.Nasa.Gov (Alan S. Mazer) (12/01/88)
I need some advice. I've got some color imaging stuff written in SunView
which I am thinking of porting to X. Can anyone tell me how practical
this is? I understand that X can do color imaging. The potential problem
is that Suns tend to "lose" the colormap of a window with its own 256
colors when the cursor is not within the window. Is this a problem in X
as well, or does X somehow handle this properly? (I get around this
problem in SunView with a lot of kludges.)
-- Alan ..!{ames,cit-vax}!elroy!alan * "But, seriously, what can
alan@elroy.jpl.nasa.gov go wrong?"hvr%kimba@Sun.COM (Heather Rose) (12/07/88)
In article <11695@elroy.Jpl.Nasa.Gov> alan@cogswell.Jpl.Nasa.Gov (Alan S. Mazer) writes: >I need some advice. I've got some color imaging stuff written in SunView >which I am thinking of porting to X. Can anyone tell me how practical >this is? I understand that X can do color imaging. The potential problem >is that Suns tend to "lose" the colormap of a window with its own 256 >colors when the cursor is not within the window. Is this a problem in X >as well, or does X somehow handle this properly? (I get around this >problem in SunView with a lot of kludges.) > >-- Alan ..!{ames,cit-vax}!elroy!alan * "But, seriously, what can > alan@elroy.jpl.nasa.gov go wrong?" "Losing the color" when the window loses the focus is a limitation of the display hardware. This will happen with any window system with dynamic colormaps on any display framebuffer that is only 8 bits deep. One way around this which X11 uses is the concept of a static colormap. Each window shares the same 256 colors, but you don't have the freedom to set all 256 colors yourself. X11 also will partition up the available 256 colors in various ways to allow some things to be shared while others are settable. If you have a framebuffer that is 24 bits deep, then you can store the true RGB values for each pixel's color, thus colormaps are not needed, you always get the color you've asked for, and there is no "flashing." For detailed information on how X11 handles color, I would suggest the chapter on color in the O'Reilly book and the "Visualizing X11 Clients" paper to be given by Dave Lemke and David Rosenthal at this coming winter USENIX conference. It's a complicated subject. Heather