shell/zoom: Increment/decrement disable_planes only when zoom.active changes

disable_planes should only be incremented when zoom.active actually
toggles. Otherwise the counter will be incremented too many times,
and planes will no longer get used.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>

src/shell.c

@@ -2438,7 +2438,7 @@ do_zoom(struct wl_seat *seat, uint32_t time, uint32_t key, uint32_t axis,
 				output->zoom.level = 0.0;
 			else if (output->zoom.level > output->zoom.max_level)
 				output->zoom.level = output->zoom.max_level;
-			else {
+			else if (!output->zoom.active) {
 				output->zoom.active = 1;
 				output->disable_planes++;
 			}

src/zoom.c

@@ -123,7 +123,7 @@ weston_zoom_frame_z(struct weston_animation *animation,
 		output->zoom.spring_z.current = 0.0;
 
 	if (weston_spring_done(&output->zoom.spring_z)) {
-		if (output->zoom.level <= 0.0) {
+		if (output->zoom.active && output->zoom.level <= 0.0) {
 			output->zoom.active = 0;
 			output->disable_planes--;
 		}