From: mert0407 AT sable DOT ox DOT ac DOT uk (George Foot)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegro + Logitech Mouse
Date: 10 Jul 1997 22:09:30 GMT
Organization: Oxford University, England
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Wisher (wisher AT ms6 DOT hinet DOT net) wrote:
: I have seen articles mentioned that Logitech is slow with Allegro, and
: it really is.

: How can I get over this problem so the user can use whatever mouse
: they own (without any adjustments from them)?

I'm not sure there is a sensible way without replacing most of Allegro's
mouse functions. You could simply multiply the coordinates by a constant
and plot your own pointer, which would lower the effective resolution of
the mouse's motion. Ideally, though, you would call the driver direct to
find out how far the mouse had moved since last time you asked. This is
function 11 I think, and returns X-change and Y-change in CX and DX
respectively (they are signed shorts). It's measured in mickeys, which are
the smallest detectable mouse movement amounts. You would add these
results to your mouse X and Y coordinate variables, clip to the size you
want, and scale onto the screen to plot the cursor.

The problem with the logitech drivers is that they don't allow you to
specify the sensitivity, I think; using the mickey technique you handle
that sort of thing yourself. Having done this, you could still use
Allegro's mouse_b to check the button states. The disadvantage here is of
course that you must manually poll the mouse and plot the pointer; the way
Allegro normally does it has the mouse's position variables updated
automatically whenever the mouse moves, and the cursor is also moved
automatically.

Using mickeys and your own motion-tracking routines does have other subtle
advantages too; you have a lot more control over things, when the mouse
leaves the screen you know by how much it did, it enables you to use mouse
control in the same way as Quake and Doom, etc etc. This is all in Allegro
Vivace, which may be finished by next Christmas if we're lucky ;)

-- 
George Foot <mert0407 AT sable DOT ox DOT ac DOT uk>
Merton College, Oxford