On Thu, 13 Jul 2000, Sergio Masci wrote:
> Could someone please answer Pradeep's query. I have no experience of
> vga_waitevent, keyboard_update or keyboard_getstate (I use mouse_update
Probably this is my turn, I wrote vga_waitevent().
> > From: Pradeep Tumati <[EMAIL PROTECTED]>
> > Subject: mouse - svgalib
> > Message-id: <[EMAIL PROTECTED]>
> > Hello sir,
> > here is a sample program. It combines all the raw text, vga mode and the
> > mouse. Can you please tell me where should I put the vga_waitevent to make
> > this work...
> > int main( )
> > {
> > int a,b ;
> > char *ret;
> > a=vga_init( );
> > if (a==0)
> > {
> > vga_setmode(4);
> > vga_setmousesupport(1);
# You should enable the mouse before the setmode.. It needs to know the
# screen rez for wrapping (should not be a problem though).
> > b=keyboard_init( );
# I'd also feel more comfortable to set the keyboard before the screen,
# but it is ok this way around
> > if (b==0)
> > {
Here you need to add the vga_waitevent(). However, it also means the
structure of your program is completely changed to an even driven scheme.
(at least it should be). W/o trying to compile/run this, my suggestion:
int event;
/* this buffer is static, BTW, you only
need to call ret=keyboard_getstate()
once: */
ret=keyboard_getstate( );
for (;;) {
event = vga_waitevent(VGA_MOUSEEVENT |
VGA_KEYEVENT, NULL, NULL, NULL, NULL);
if (event & VGA_KEYEVENT) {
if (ret[SCANCODE_ESCAPE]) {
/* do something. Probably you
want this: */
break;
}
if ... check for other keys.
}
if (event & VGA_MOUSEEVENT) {
x = mouse_getx( );
y = mouse_gety( );
/* do some mouse pointer updating etc.. */
}
}
> > keyboard_update( );
> > ret=keyboard_getstate( );
> > while(!ret[SCANCODE_ESCAPE])
> > {
> > ret=keyboard_getstate( );
> > x=mouse_getx( );
> > y= mouse_gety( );
> > /* I guess it is here, if it is so, what about the keyboard update event
> > in the next line?
You don't need to call the _update funcs.. waitevent does that already
for you. However, calling them is no problem (except a waste of CPU
time), as long as you choose the non-blocking variants.
You COULD indeed add vga_waitevent(VGA_MOUSEEVENT | VGA_KEYEVENT, NULL...)
here. It would work.. but in your philosophy a mouse_update would then be
missing (but vga_waitevent does that anyway) and you would not use that
vga_waitevent returns already what kind of even actually occured (so you'd
waste a little bit of CPU time).
Theoretically it would make more sense to add it in front of x=mouse_getx(
);, BTW: Because you read the mouse coords only after they've changed.
Not a problem though as this is only in the first loop. In that light,
do { ....} while(!ret[SCANCODE_ESCAPE]) would be more sensible too.
You only check for Escape key when a key was actually pressed (not
before).
The only benefit the vga_waitevent would have is your program would not
use 100% cpu time.
Note that vga_waitevent() may return 0 even in this simple setup
if a signal was sent to your process.
> > keyboard_update( );
> > }
> > }
> > }
> > }
I also invite you to study the eventtest.c demo program which is packed
with svgalib.
Hope this helps,
Michael.
--
Michael Weller: [EMAIL PROTECTED], [EMAIL PROTECTED],
or even [EMAIL PROTECTED] If you encounter an eowmob account on
any machine in the net, it's very likely it's me.
