compositor: update scissor region before using it

Subsurfaces inherit the scissor region from the parent surface. Currently
the region is updated at the end of weston_view_update_transform(). As a
result, the old region is used to clip the transform.boundingbox of the
subsurface.

Change the order to update the scissor region after the transform.matrix is
updated but before it is used.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>

libweston/compositor.c

@@ -1415,6 +1415,25 @@ view_compute_bbox(struct weston_view *view, const pixman_box32_t *inbox,
 				  ceilf(max_x) - int_x, ceilf(max_y) - int_y);
 }
 
+static void
+weston_view_update_transform_scissor(struct weston_view *view,
+				     pixman_region32_t *region)
+{
+	struct weston_view *parent = view->geometry.parent;
+
+	if (parent) {
+		if (parent->geometry.scissor_enabled) {
+			view->geometry.scissor_enabled = true;
+			weston_view_transfer_scissor(parent, view);
+		} else {
+			view->geometry.scissor_enabled = false;
+		}
+	}
+
+	if (view->geometry.scissor_enabled)
+		pixman_region32_intersect(region, region,
+					  &view->geometry.scissor);
+}
 static void
 weston_view_update_transform_disable(struct weston_view *view)
 {
@@ -1439,10 +1458,8 @@ weston_view_update_transform_disable(struct weston_view *view)
 				  0, 0,
 				  view->surface->width,
 				  view->surface->height);
-	if (view->geometry.scissor_enabled)
-		pixman_region32_intersect(&view->transform.boundingbox,
-					  &view->transform.boundingbox,
-					  &view->geometry.scissor);
+
+	weston_view_update_transform_scissor(view, &view->transform.boundingbox);
 
 	pixman_region32_translate(&view->transform.boundingbox,
 				  view->geometry.x, view->geometry.y);
@@ -1498,9 +1515,9 @@ weston_view_update_transform_enable(struct weston_view *view)
 
 	pixman_region32_init_rect(&surfregion, 0, 0,
 				  view->surface->width, view->surface->height);
-	if (view->geometry.scissor_enabled)
-		pixman_region32_intersect(&surfregion, &surfregion,
-					  &view->geometry.scissor);
+
+	weston_view_update_transform_scissor(view, &surfregion);
+
 	surfbox = pixman_region32_extents(&surfregion);
 
 	view_compute_bbox(view, surfbox, &view->transform.boundingbox);
@@ -1560,15 +1577,6 @@ weston_view_update_transform(struct weston_view *view)
 		pixman_region32_fini(&mask);
 	}
 
-	if (parent) {
-		if (parent->geometry.scissor_enabled) {
-			view->geometry.scissor_enabled = true;
-			weston_view_transfer_scissor(parent, view);
-		} else {
-			view->geometry.scissor_enabled = false;
-		}
-	}
-
 	weston_view_damage_below(view);
 
 	weston_view_assign_output(view);