Path: utzoo!utgpu!watserv1!watmath!att!att!linac!uwm.edu!rpi!zaphod.mps.ohio-state.edu!usc!samsung!munnari.oz.au!bruce!merlin!paulg
From: paulg@bhpmrl.oz.au (Paul Gallagher)
Newsgroups: comp.lang.pascal
Subject: Re: WEIRD MOUSE CURSOR ON VGA 640X480
Message-ID: <1990Nov28.073307.3210@bhpmrl.oz.au>
Date: 28 Nov 90 07:33:07 GMT
References: <11573@j.cc.purdue.edu>
Sender: usenet@bhpmrl.oz.au (USEnet nntp account)
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If I understand you right, you get wierd mouse cursor effects in graphics
mode even if you hide the cursor prior to drawing any object on the screen.

This sounds very much like a conflict between BGI and the mouse driver.

I can't add any more, except another question - directed to anyone. 

I program using Turbo Pascal mainly, and like many people,
I have a mouse unit the handles alL
the mouse functions (via int 33h). I even went out and bought the 
Microsoft Mouse Programmer's Guide. I got all the text mouse routines under
control in no time, but what I really wanted to do was implement a 
grapohics mouse (I had EGA at the time). The MS Mouse Programmer's Guide
had a short piece on EGA support, which basically said link EGA.LIB
with your program and do all your manipulation of the EGA registers via
the pseudo-registers in EGA.LIB. Well, Microsoft's Microsoft and Borland's
BorlanD, and anyone with any brains will never even try to mix products! 
(unlike me!). My first problem was trying to effect the link. I don't
think I ever firured it out! (can anyone enlighten me as to how it can
be done, or why it can't?) I tried binobj ---> EGA.OBJ {$L ... etc, no luck!
However, that wasn't the main concern: if you weren't supposed to 
buggerize around with the EGA regs direct, then that would mean chucking
BGI out the window. Iwasn't about to do that. 

(btw, have I mentioned that in all of the other - lower rez - graphics
modes the mouse was working fin, but when the same routines were tried
in EGA mode  - hi or lo rez - I got no cursor at all, and the mouse thought
the screen was only 200 pixels high)

Back to the story. I ended up keeping BGI (predictably) and writing a
substitute mouse interrupt service routine that handled all mouse events
I then used BGI to draw the mouse cursor. Had a few hairies getting 
around the re-entrancy problem, but it all eventually worked fine, you
might even say responsively. 

As you may have guessed, I gave up even trying to do it the way
Microsoft was recommending. However, I've never compared my experiences
with those of others. When I read some of the mail on the subject, I
sometimes get the impression that other people HAVEN'T had problems 
getting graphical mouse units off the ground using Turbo Pascal (using
EGA or VGA) I've often wondered whether it's just that my EGA card wasn't
100% IBM compatible.

I would be very interested to hear of other's experiences with graphical
mouse support, especially using Turbo Pascal.


     /\/\       Paul Gallagher, PC Support Officer,
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