| Re: memory for pixmaps: big vs many [message #54598 is a reply to message #54597] |
Thu, 21 June 2007 14:05  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Richard Clark writes:
> In using offscreen pixmaps to preload a sequence of images for smooth
> display in an animation you can run up against memory limitations in the
> graphics hardware.
> Does anyone have experience with this on multiple platforms and could
> comment? For instance, any OS-wide generalizations that can be made,
> or is it hopelessly graphics card dependent?
Not only is it graphics card dependent, but in my
experience there is direct correlation between the
importance of the job and the number of pixmap problems
you run into. :-)
> On a related note, the animation I'm interested in displaying is made
> up of b&w images. So using an 8 bit rather than 24 bit mode should
> make room for more images to be loaded in the card's memory.
>
> Does using an 8 bit mode make room for 3x, 4x, or 1x times as many
> images?
I'm not aware that you can create pixmaps in anything other than
the default OS dependent flavor.
Sorry I don't have better information to convey. But I will
tell you about one little wrinkle I have used successfully
in my Catalyst Library. There pixmaps are simply draw widgets
in unmapped top-level base widgets. We did this to get around
the video ram problems you mention, but I can't remember now whether
this was strictly due to smaller windows, or because real windows
don't use pixmap memory in the same way that pixmaps do. In any
case, it worked and solved our problems.
The was one very nice bonus to creating pixmaps this way.
Whenever we wanted to see what was on a pixmap, all we had
to do was set its MAP property, and it immediately showed up
on the display. VERY handy for debugging purposes!
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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