Date: Wed, 02 Oct 1996 09:18:21 +0000
From: Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
Subject: Re: Setting the mouse callback function
To: Tero DOT Parvinen AT hut DOT fi
Cc: djgpp AT delorie DOT com
Message-id: <3252335D.24E6@blackmagic.tait.co.nz>
Organization: Tait Electronics NZ
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References: <tparvine DOT 844079282 AT snakemail DOT hut DOT fi>

Tero Parvinen wrote:
> 
> I downloaded the sample-interrupt-handlers-v2.zip package from www.delorie.com
> and I tried to use the functions in mouse.s.
> I can't get the m_setUserFunction function to work.
> 
> I'm not sure about the syntax because the package is not exactly well documented.
> I suppose the first parameter is the
> address of the callback function and the second is the mask for the events. I
> suppose I don't have to use the dpmi-functions
> to make a callback wrapper because the mouse routines provide one if I interpreted
> the mouse.s file correctly.
> 
> So what I would like to do is declare a pure C-function which would get called by
> the mouse handler. How should I declare
> the C-function and what should I pass as the first parameter of m_setUserFunction?
> 
> If someone has managed to do this, any help would be appreciated.
> I would prefer an answer in e-mail if possible. (Tero DOT Parvinen AT hut DOT fi is a good
> address ;) )

Sorry about the lack of docs.

Here's how to use the callback function:

void c_callback_function(short mask, short mouse_x, short mouse_y, 
                                     short delta_x, short delta_y,
                                     short button_flags)
{
/* mask the the set of events that cause the callback to trigger */
...
}

mouse_event_handler_initialization_function()
{
m_init();  /* allocatate the callback and lock the mouse memory */

/*Don't forget to lock your callback function and it's data!!!!*/
m_setUserFunction(c_callback_function,mask_for_mouse_events);
/* mask_for_events is used to determine when your function gets called
 * I usually use 0xffff to get all possible events (see Ralf Brown's
 * list for more details
 */
...
}

mouse_event_handler_deinitialization_function()
{
m_uninit(); /* dellocate the callback and unlock the mouse memroy */
}


Hope this helps
Bill