static void middle_drag(int dx) {
scope_disp_t *disp = &(ctrl_usr->disp);
scope_horiz_t *horiz = &(ctrl_usr->horiz);
double dt = (dx / disp->pixels_per_sample) / ctrl_shm->rec_len;
set_horiz_pos(horiz->pos_setting + 5 * dt);
refresh_display();
}
static void change_zoom(int dir, int x) {
scope_horiz_t *horiz = &(ctrl_usr->horiz);
scope_disp_t *disp = &(ctrl_usr->disp);
double old_pixels_per_sample, pixels_per_div,
pixels_per_sec, new_pixels_per_sample, old_fraction, new_fraction;
old_pixels_per_sample = disp->pixels_per_sample;
set_horiz_zoom(horiz->zoom_setting + dir);
/* calculate horizontal params that depend on width */
pixels_per_div = disp->width * 0.1;
pixels_per_sec = pixels_per_div / horiz->disp_scale;
disp->pixels_per_sample = new_pixels_per_sample =
pixels_per_sec * horiz->sample_period;
// how many samples away from the center of the window is this
// pixel?
old_fraction = (x - disp->width / 2) / old_pixels_per_sample / ctrl_shm->rec_len;
// and new?
new_fraction = (x - disp->width / 2) / new_pixels_per_sample / ctrl_shm->rec_len;
// displace by the difference
set_horiz_pos( horiz->pos_setting - new_fraction + old_fraction );
}
static char *hpos_cmd(void * arg)
{
double *argp;
int rv;
argp = (double *)(arg);
rv = set_horiz_pos(*argp);
if ( rv < 0 ) {
return "could not set horizontal position";
}
return NULL;
}
