compositor: split weston_surface_update_transform()

Split two helper functions out of weston_surface_update_transform() to:
- make the code clearer
- update the bounding box properly even if transformation fails
- unify the return point

Also add a comment on what matrix.d[12] is.

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

diff --git a/src/compositor.c b/src/compositor.c
index 1c35585..556aad4 100644 (file)
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -280,37 +280,28 @@ surface_compute_bbox(struct weston_surface *surface, int32_t sx, int32_t sy,
                                  max_x - min_x + 1, max_y - min_y + 1);
 }
 
-WL_EXPORT void
-weston_surface_update_transform(struct weston_surface *surface)
+static void
+weston_surface_update_transform_disable(struct weston_surface *surface)
+{
+       surface->transform.enabled = 0;
+
+       pixman_region32_init_rect(&surface->transform.boundingbox,
+                                 surface->geometry.x,
+                                 surface->geometry.y,
+                                 surface->geometry.width,
+                                 surface->geometry.height);
+}
+
+static int
+weston_surface_update_transform_enable(struct weston_surface *surface)
 {
        struct weston_matrix *matrix = &surface->transform.matrix;
        struct weston_matrix *inverse = &surface->transform.inverse;
        struct weston_transform *tform;
 
-       if (!surface->geometry.dirty)
-               return;
-
-       surface->geometry.dirty = 0;
-
-       pixman_region32_fini(&surface->transform.boundingbox);
-
-       /* transform.position is always in transformation_list */
-       if (surface->geometry.transformation_list.next ==
-           &surface->transform.position.link &&
-           surface->geometry.transformation_list.prev ==
-           &surface->transform.position.link) {
-               surface->transform.enabled = 0;
-
-               pixman_region32_init_rect(&surface->transform.boundingbox,
-                                         surface->geometry.x,
-                                         surface->geometry.y,
-                                         surface->geometry.width,
-                                         surface->geometry.height);
-               return;
-       }
-
        surface->transform.enabled = 1;
 
+       /* Otherwise identity matrix, but with x and y translation. */
        surface->transform.position.matrix.d[12] = surface->geometry.x;
        surface->transform.position.matrix.d[13] = surface->geometry.y;
 
@@ -320,14 +311,37 @@ weston_surface_update_transform(struct weston_surface *surface)
 
        if (weston_matrix_invert(inverse, matrix) < 0) {
                /* Oops, bad total transformation, not invertible */
-               surface->transform.enabled = 0;
                fprintf(stderr, "error: weston_surface %p"
                        " transformation not invertible.\n", surface);
+               return -1;
        }
 
        surface_compute_bbox(surface, 0, 0, surface->geometry.width,
                             surface->geometry.height,
                             &surface->transform.boundingbox);
+       return 0;
+}
+
+WL_EXPORT void
+weston_surface_update_transform(struct weston_surface *surface)
+{
+       if (!surface->geometry.dirty)
+               return;
+
+       surface->geometry.dirty = 0;
+
+       pixman_region32_fini(&surface->transform.boundingbox);
+
+       /* transform.position is always in transformation_list */
+       if (surface->geometry.transformation_list.next ==
+           &surface->transform.position.link &&
+           surface->geometry.transformation_list.prev ==
+           &surface->transform.position.link) {
+               weston_surface_update_transform_disable(surface);
+       } else {
+               if (weston_surface_update_transform_enable(surface) < 0)
+                       weston_surface_update_transform_disable(surface);
+       }
 }
 
 static void