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In article <7632@pasteur.Berkeley.EDU> soohoo@cory.Berkeley.EDU.UUCP (Ken Soohoo) writes:
>In article <1988Nov19.180454.563@gpu.utcs.toronto.edu> romwa@gpu.utcs.toronto.edu (Mark Dornfeld) writes:
>>
>>When using the GEM event manager, is there a way of setting up
>>an event which involves clicking one OR two buttons?  I
>>am thinking of a case like the desktop, where one can select a
>>disk by clicking once and get a directory by double-clicking.
>>
>>
>>Pavneet Arora
>>...!utgpu!rom!pavneet
>
>2) If you want to sense two click on _different_ buttons, you're going
>to have to go to a little work:
> 	
>	The problem is that the evnt_multi() evnt_button() routines
>	just don't return anything other than the left button being
>	clicked (although you _can_ properly sense a right click with
>	graf_mkstate() and vq_mouse(), and I'd use graf_mkstate() with
>	other 'desktop' routines like evnt_ calls).
>
>--Kenneth Soohoo	(soohoo@cory.Berkeley.Edu)
>  Atari 400/800/600xl/800xl/1200/130xe/65xe, 1040ST hacker
>  Sometime Berkeley Student, othertimes...
>  My opinions are my OWN, not necessarily Atari's


Dear Kenneth,

That is not entirely true:

evnt_multi and evnt_button can be used to properly detect a right button event,
you cannot however wait for both a right and a left button event at the same
time (seems silly but thats the way it works).

If you use graf_mkstate, you will observe two things:

	1) It is SLOOOOWW in returning the mouse state, and
	2) It will buffer up waiting for a key event, in other words, if you
	   call graf_mkstate 3 times, you will lose the next three key strokes!

We use a modified handler for using the right and left mouse button interaction
by using vq_mouse, but this too has its problems.  We will shortly change all
vq_mouse calls to direct memory peeks using line-a offsets.  But using the
vq_mouse call wouldcause the problem of the button click being cached and
the next time an evnt_multi (MU_BUTTON) or evnt_button is called, that button
click will be captured.  In other words, sampling the mouse state using
vq_mouse (and getting bstate == 1) will cause a left button event to occur for
the next evnt_button call!

To get around this awkwardness, do something like:

do {
    vq_mouse(handle, &bstate, &x, &y);
    if (bstate & 1)
        evnt_button(left mouse stuff);
    if (bstate & 2)
        evnt_button(right mouse stuff);
} while (bstate != your exit condition);

This, however, only tests for single button clicks.  Double button clicks is
much more extensive if it is for both buttons to be sampled.

- mike

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