C - nanosleep and drawing with cairo

[xl_cheese]

I can't figure out how to use the nanosleep function when drawing with the cairo lib.

Basically I want to draw a line, sleep ~.5s, and then draw another line. What I'm seeing is there is no delay at all. Both lines are drawn at the same time.

Any help would be appreciated and I'll note that I'm a total coding noob so if you could dumb it down for that that would be great.

ge_cairo_rounded_rectangle (cr, 0, 0, width-1, height-1, radius+1, params->corners);
ge_shade_color (&params->parentbg, 0.96, &glow);
ge_cairo_set_color (cr, &glow);
cairo_stroke (cr);
nanosleep (500000000, NULL);
ge_cairo_rounded_rectangle (cr, 1, 1, width-2, height-2, radius+1, params->corners);
ge_shade_color (&params->parentbg, 0.92, &glow);
ge_cairo_set_color (cr, &glow);
cairo_stroke (cr);

Thanks!

[wolfbone]

500000000 is not a 'struct timespec *'


struct timespec * intvl = (struct timespec *) malloc(sizeof(struct timespec));

intvl->tv_sec = 0L;

intvl->tv_nsec = 500000000L;

....

nanosleep(intvl,NULL);

[wdk]

If you really want/need to use nanosleep, you will first need to initialize a timespec structure containing the appropriate sleep value.

The timespec struct is defined as:


struct timespec {
time_t tv_sec; /*seconds*/
long tv_nsec; /*nanoseconds*/
}


so, you will need to insert something to the effect of:


struct timespec t;

/* other code */

t.tv_sec = 0.0
t.tv_nsec = 500000000;
nanosleep(&t, NULL);


check the nanosleep man page for more exciting details...

Hope this helps!

[xl_cheese]

Thanks guys!

The delay works. Only problem is that it delays then draws both rectangles at the same time instead of 1st rectangle, delay, and 2nd rectangle.

[amo-ej1]

perhaps usleep would be a simpler solution (man usleep) this simply eats the amount of microseconds to sleep as a first parameter.

[wolfbone]

Thanks guys!

The delay works. Only problem is that it delays then draws both rectangles at the same time instead of 1st rectangle, delay, and 2nd rectangle.

Probably because the 'drawing' is being done to the 'cr', which will be just some piece of memory. I don't know cairo (or ge_cairo, whatever that is) so I don't know how you'd force an on-screen update before the nanosleep with it.