gles2: update texture only if needed

When a surface is on a non-primary plane (overlay), we do not need to
keep the GL texture up-to-date, since we are not using it. Avoid calling
glTex(Sub)Image2D in that case, and accumulate the texture damage
separately.

This is especially useful for backends, that can put wl_shm buffers into
overlays.

The empty damage check has to be moved from surface_accumulate_damage()
into gles2_renderer_flush_damage(), because it really needs to check the
accumulated damage, not only the current damage. Otherwise, if a surface
migrates from a plane to the primary plane, and does not have new
damage, the texture would not be updated even for accumulated damage.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

src/compositor.c

@@ -239,6 +239,7 @@ weston_surface_create(struct weston_compositor *compositor)
 
 	surface->num_textures = 0;
 	surface->num_images = 0;
+	pixman_region32_init(&surface->texture_damage);
 
 	surface->buffer = NULL;
 	surface->output = NULL;
@@ -782,6 +783,7 @@ destroy_surface(struct wl_resource *resource)
 	if (surface->buffer)
 		wl_list_remove(&surface->buffer_destroy_listener.link);
 
+	pixman_region32_fini(&surface->texture_damage);
 	compositor->renderer->destroy_surface(surface);
 
 	pixman_region32_fini(&surface->transform.boundingbox);
@@ -905,8 +907,7 @@ static void
 surface_accumulate_damage(struct weston_surface *surface,
 			  pixman_region32_t *opaque)
 {
-	if (pixman_region32_not_empty(&surface->damage) &&
-	    surface->buffer && wl_buffer_is_shm(surface->buffer))
+	if (surface->buffer && wl_buffer_is_shm(surface->buffer))
 		surface->compositor->renderer->flush_damage(surface);
 
 	if (surface->transform.enabled) {

src/compositor.h

@@ -410,6 +410,7 @@ struct weston_surface {
 	struct weston_compositor *compositor;
 	GLuint textures[3];
 	int num_textures;
+	pixman_region32_t texture_damage;
 	pixman_region32_t clip;
 	pixman_region32_t damage;
 	pixman_region32_t opaque;

src/gles2-renderer.c

@@ -775,6 +775,18 @@ gles2_renderer_flush_damage(struct weston_surface *surface)
 	int i, n;
 #endif
 
+	pixman_region32_union(&surface->texture_damage,
+			      &surface->texture_damage, &surface->damage);
+
+	/* Avoid upload, if the texture won't be used this time.
+	 * We still accumulate the damage in texture_damage.
+	 */
+	if (surface->plane != &surface->compositor->primary_plane)
+		return;
+
+	if (!pixman_region32_not_empty(&surface->texture_damage))
+		return;
+
 	glBindTexture(GL_TEXTURE_2D, surface->textures[0]);
 
 	if (!surface->compositor->has_unpack_subimage) {
@@ -783,14 +795,14 @@ gles2_renderer_flush_damage(struct weston_surface *surface)
 			     GL_BGRA_EXT, GL_UNSIGNED_BYTE,
 			     wl_shm_buffer_get_data(surface->buffer));
 
-		return;
+		goto done;
 	}
 
 #ifdef GL_UNPACK_ROW_LENGTH
 	/* Mesa does not define GL_EXT_unpack_subimage */
 	glPixelStorei(GL_UNPACK_ROW_LENGTH, surface->pitch);
 	data = wl_shm_buffer_get_data(surface->buffer);
-	rectangles = pixman_region32_rectangles(&surface->damage, &n);
+	rectangles = pixman_region32_rectangles(&surface->texture_damage, &n);
 	for (i = 0; i < n; i++) {
 		glPixelStorei(GL_UNPACK_SKIP_PIXELS, rectangles[i].x1);
 		glPixelStorei(GL_UNPACK_SKIP_ROWS, rectangles[i].y1);
@@ -801,6 +813,10 @@ gles2_renderer_flush_damage(struct weston_surface *surface)
 				GL_BGRA_EXT, GL_UNSIGNED_BYTE, data);
 	}
 #endif
+
+done:
+	pixman_region32_fini(&surface->texture_damage);
+	pixman_region32_init(&surface->texture_damage);
 }
 
 static void