compositor: Track which plane a surface is on

We start tracking which hardware plane a surface is displayed on, which
lets us avoid generating damage when a hardware overlay/cursor is moved
around.

src/compositor-drm.c

@@ -42,6 +42,10 @@
 #include "launcher-util.h"
 #include "log.h"
 
+enum {
+	WESTON_PLANE_DRM_CURSOR = 0x100
+};
+
 struct drm_compositor {
 	struct weston_compositor base;
 
@@ -635,7 +639,6 @@ weston_output_set_cursor(struct weston_output *output,
 			 pixman_region32_t *overlap)
 {
 	pixman_region32_t cursor_region;
-	int prior_was_hardware;
 
 	if (seat->sprite == NULL)
 		return;
@@ -650,19 +653,18 @@ weston_output_set_cursor(struct weston_output *output,
 		goto out;
 	}
 
-	prior_was_hardware = seat->hw_cursor;
 	if (pixman_region32_not_empty(overlap) ||
 	    drm_output_set_cursor(output, seat) < 0) {
-		if (prior_was_hardware) {
+		if (seat->sprite->plane == WESTON_PLANE_DRM_CURSOR) {
 			weston_surface_damage(seat->sprite);
 			drm_output_set_cursor(output, NULL);
 		}
-		seat->hw_cursor = 0;
+		seat->sprite->plane = WESTON_PLANE_PRIMARY;
 	} else {
-		if (!prior_was_hardware)
+		if (seat->sprite->plane == WESTON_PLANE_PRIMARY)
 			weston_surface_damage_below(seat->sprite);
 		wl_list_remove(&seat->sprite->link);
-		seat->hw_cursor = 1;
+		seat->sprite->plane = WESTON_PLANE_DRM_CURSOR;
 	}
 
 out:
@@ -705,7 +707,7 @@ drm_assign_planes(struct weston_output *output)
 			weston_output_set_cursor(output, seat,
 						 &surface_overlap);
 
-			if (!seat->hw_cursor)
+			if (seat->sprite->plane == WESTON_PLANE_PRIMARY)
 				pixman_region32_union(&overlap, &overlap,
 						      &es->transform.boundingbox);
 		} else if (!drm_output_prepare_overlay_surface(output, es,

src/compositor.c

@@ -306,6 +306,9 @@ weston_surface_damage_below(struct weston_surface *surface)
 	struct weston_compositor *compositor = surface->compositor;
 	pixman_region32_t damage;
 
+	if (surface->plane != WESTON_PLANE_PRIMARY)
+		return;
+
 	pixman_region32_init(&damage);
 	pixman_region32_subtract(&damage, &surface->transform.boundingbox,
 				 &surface->clip);

src/compositor.h

@@ -222,7 +222,6 @@ struct weston_seat {
 	int32_t hotspot_x, hotspot_y;
 	struct wl_list link;
 	enum weston_keyboard_modifier modifier_state;
-	int hw_cursor;
 	struct wl_surface *saved_kbd_focus;
 	struct wl_listener saved_kbd_focus_listener;
 
@@ -382,6 +381,10 @@ struct weston_region {
  * transformation in global coordinates, add it to the tail of the list.
  */
 
+enum {
+	WESTON_PLANE_PRIMARY
+};
+
 struct weston_surface {
 	struct wl_surface surface;
 	struct weston_compositor *compositor;
@@ -398,6 +401,7 @@ struct weston_surface {
 	GLfloat opaque_rect[4];
 	GLfloat alpha;
 	int blend;
+	int plane;
 
 	/* Surface geometry state, mutable.
 	 * If you change anything, set dirty = 1.