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Dear Yonggang,

> I have a black box in magic layout window. I have seen the massages in
> magic archive 2002. It seems that is due to my 16bit color depth of my
> Linux.

Normally, you should be running X in 24- or 32- bit color depth, if you
have the video memory to support it at a reasonable refresh rate.  I
don't know why 16-bit depth results in a black box but 24-bit depth
results in a white box.

> I tried to setup my Linux running in 8bit color depth. In this way, the
> magic layout window runs well. However, when I switch between layout
> window and terminal window ( on which magic depends to run), my screen
> always flashs. I can't see the text in terminal window clearly.

> How to deal with it?

A very standard problem.  There are a couple of solutions.  The simplest
would be to choose a very simple color scheme for an xterm (like black-on-
white or white-on-black) and always start magic from there, where it will
not flash, and won't get re-mapped to colors so similar that you can't
see what's on the terminal screen.

Another solution is to have a graphics card capable of 8-bit overlays.
However, I haven't found much support for this.  I just changed to a
Matrox G550 card which is *supposed* to have support for 8-bit overlays
in XFree86, but when I turn the option on, the X server crashes.  I
used to have a Permedia2-based card and an X server by Xi graphics.  It
had a few bugs, but the overlays worked.

Even if your graphics card doesn't support overlays, it may support
hardware-accelerated color blends, in which case you can compile magic
with both X11 and OpenGL support, and run magic with the "-dOGL" option.
Matrox cards support hardware color blends, but ATI cards don't.  Starting
with RedHat version 7.0 (I think), OpenGL is built into the X server, but
whether it uses hardware acceleration or not depends on the video card.
So you can always compile magic with OpenGL and run it, but if you don't
have the hardware accelerated color blends, you will certainly find that
its drawing rate is VERY slow.

However, if you don't want to mess with video card and X server issues,
your best bet is to contact Steve Tell (tell AT telltronics DOT org) and ask
for his "color snarfer" patch to the magic source.  It contains a
utility program that is run when X starts up, and makes sure that as the
X server allocates colors, it stays away from the areas of the colormap
that magic wants to use.  Even when the colormap is full, it tries to
map similar colors to similar positions in the colormap to minimize the
screen flashing.

						Regards,
						Tim

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