libweston: Move output damage subtraction out of backends

Right now every backend clears output damage from the primary plane when
it repaints. Instead of having this same operation spread across all
the backends, just do it in the core instead.

In the future, we want to remove damage tracking from the primary plane
entirely, and this is a small step in that direction.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>

libweston/backend-drm/drm.c

@@ -415,9 +415,6 @@ drm_output_render(struct drm_output_state *state, pixman_region32_t *damage)
 
 	scanout_state->zpos = scanout_plane->zpos_min;
 
-	pixman_region32_subtract(&c->primary_plane.damage,
-				 &c->primary_plane.damage, damage);
-
 	/* Don't bother calculating plane damage if the plane doesn't support it */
 	if (damage_info->prop_id == 0)
 		return;

libweston/backend-headless/headless.c

@@ -167,9 +167,6 @@ headless_output_repaint(struct weston_output *output_base,
 	ec->renderer->repaint_output(&output->base, damage,
 				     output->renderbuffer);
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
-
 	wl_event_source_timer_update(output->finish_frame_timer, 16);
 
 	return 0;

libweston/backend-pipewire/pipewire.c

@@ -789,8 +789,6 @@ pipewire_output_repaint(struct weston_output *base, pixman_region32_t *damage)
 
 	pipewire_submit_buffer(output, buffer);
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
 out:
 
 	pipewire_output_arm_timer(output);

libweston/backend-rdp/rdp.c

@@ -317,9 +317,6 @@ rdp_output_repaint(struct weston_output *output_base, pixman_region32_t *damage)
 		pixman_region32_fini(&transformed_damage);
 	}
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
-
 	wl_event_source_timer_update(output->finish_frame_timer, next_frame_delta);
 	return 0;
 }

libweston/backend-vnc/vnc.c

@@ -957,8 +957,6 @@ vnc_output_repaint(struct weston_output *base, pixman_region32_t *damage)
 
 	if (pixman_region32_not_empty(damage)) {
 		vnc_update_buffer(output->display, damage);
-		pixman_region32_subtract(&ec->primary_plane.damage,
-					 &ec->primary_plane.damage, damage);
 	}
 
 	/*

libweston/backend-wayland/wayland.c

@@ -515,8 +515,6 @@ wayland_output_repaint_gl(struct weston_output *output_base,
 
 	ec->renderer->repaint_output(&output->base, damage, NULL);
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
 	return 0;
 }
 #endif
@@ -638,8 +636,6 @@ wayland_output_repaint_pixman(struct weston_output *output_base,
 
 	sb->frame_damaged = 0;
 
-	pixman_region32_subtract(&b->compositor->primary_plane.damage,
-				 &b->compositor->primary_plane.damage, damage);
 	return 0;
 }
 

libweston/backend-x11/x11.c

@@ -441,9 +441,6 @@ x11_output_repaint_gl(struct weston_output *output_base,
 
 	ec->renderer->repaint_output(output_base, damage, NULL);
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
-
 	wl_event_source_timer_update(output->finish_frame_timer, 10);
 	return 0;
 }
@@ -522,8 +519,6 @@ x11_output_repaint_shm(struct weston_output *output_base,
 
 	ec->renderer->repaint_output(output_base, damage, output->renderbuffer);
 
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, damage);
 	set_clip_for_output(output_base, damage);
 	cookie = xcb_shm_put_image_checked(b->conn, output->window, output->gc,
 					pixman_image_get_width(image),

libweston/compositor.c

@@ -3263,6 +3263,9 @@ weston_output_repaint(struct weston_output *output)
 
 	r = output->repaint(output, &output_damage);
 
+	pixman_region32_subtract(&ec->primary_plane.damage,
+				 &ec->primary_plane.damage, &output_damage);
+
 	pixman_region32_fini(&output_damage);
 
 	output->repaint_needed = false;