On Thu, 30 Dec 1999, Steve Lamont wrote:
> # To subscribers of the xforms list from spl@szechuan.ucsd.edu (Steve Lamont) :
>
> > I have recently recompiled my application with xforms v0.89.0, previously
> > v0.88.1. The way OpenGL canvases are handled seems to have changed:
> > whereas before a window could be moved across the canvas without causing
> > the canvas to flicker, the same program now exhibits severe flickering,
> > sometimes even displaying a black screen instead of the canvas contents.
>
> Hm. None of my OpenGL apps exhibit this behavior. It sounds as if
> perhaps Expose events aren't being handled properly or something of
> that nature.
I don't know about that. There still remains the strange fact that the
same source code, compiled with the v89 library, does produce this effect,
while compiled with the v88 library, it does not.
>
> > Question: have the glcanvas class initialization or activation routines
> > (as set by fl_modify_canvas_prop()) been changed from v0.88.1 to v0.89.0?
> > Or is this possibly a colormap issue? The manual says that "it is a good
> > idea to fill [the canvas colormap] with xforms's default colors to reduce
> > flashing."
>
> This flashing is generally only an issue if you are using color index
> mode, running on a PseudoColor (generally 8-bit) device. 24-bit
> TrueColor should not show these effects at all. PseudoColor displays
> will go "technicolor" in a rather annoying fashion as you move the
> cursor into a Window with a different Colormap.
>
> There are a few differences but none of them as far as I can tell by
> diffing them, they don't relate to fl_modify_canvas_prop().
>
> fl_modify_canvas_prop() doesn't really do much other than set the
> `init', `activate', and `cleanup' properties -- it's dumb as dirt.
>
> The handlers themselves are in `gl.c' and I don't see any significant
> difference other than some very cosmetic ones -- line breaks and the
> like.
Okay, thanks for this info. I'll have to see if I can get rid of the
flickering.
>
> spl
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Daniel Weiss tel: +49 551 399431
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