From:	"The Advisor" <TheAdvisor AT cadvision DOT com>
Newsgroups:	comp.os.msdos.djgpp
References:	<6A5W3.270$Up1 DOT 2636 AT newsfeed DOT slurp DOT net>
Subject:	Re: Still frustrated with mouse problem (actually a blitting prob)
Date:	Sun, 14 Nov 1999 02:29:29 -0700
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Organization:	Anarchy Incorporated
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

When you are blitting directly to the screen, or writing to the screen at
all, turn off the mouse cursor.  Turn the cursor back on when you are done
the blit.

In allegro:
show_mouse(NULL);
blit(blah, blah, blah);
show_mouse(screen);

do this whenever you are writing to the screen, whether it's text or a blit,
and your problem should be gone. ( unless it's a really ba dthing... my only
other advice would be to get a shotgun and shoot it :)

The Advisor ( TheAdvisor AT cadvision DOT com )

Tim B <aeronaut AT palacenet DOT net DOT REMOVE> wrote in message
news:6A5W3.270$Up1 DOT 2636 AT newsfeed DOT slurp DOT net...
> Okay, this is my second attempt at trying to find some help with this
> problem.  I originally thought this was a problem with the mouse functions
> but after doing some tests I discovered the mouse droppings were only a
> symptom of the real problem which seems to be that images blitted from the
> screen (video memory) on occasion become slightly corrupted.  That's why
the
> mouse appeared to create extra random pixels because the image under the
> mouse was originally blitted from the screen.
>
> There doesn't seem to be any problem when blitting to the screen and the
> problem only seems to happen in the svga modes.  In particular, if the
image
> is blitted from a horizontal screen position that can be divided by 4 and
> any vertical position, the image is transferred accurately.  However, if
> blitted from any other horizontal position the image sometimes becomes
> corrupted.
>
> The computer I'm currently using has a pc100 motherboard with a built in
3D
> AGP graphics adapter and a vesa compliant video bios.  I've done the same
> tests with the program on my 486/66 which has a Trident 8900 and there is
no
> problem.  Blits can be done anywhere from the screen with no corruption
> which is of course what would be expected.
>
> I also originally thought this might be due to a buggy vesa bios but I
don't
> seem to have this problem with other non-djgpp graphics programs I've
used.
> This includes an extended dos program created with dos/4gw.  So I'm
> beginning to think maybe this is a problem with DJGPP (I'm using v2.01).
>
> It seems questions are always encouraged, but it's pointless advice if
> they're never answered.  So I'm asking again.  Please, if anyone has ever
> come across this kind of thing or can suggest any possibilities for
dealing
> with it.  Is the problem in my graphics adapter?  Is it in DJGPP?  Is
there
> a patch for it?  Is it something I can fix myself?
>
>
>
>

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