[cairo] [PATCH] xcb: make use of _cairo_surface_is_xcb to check for surface type

[Ravi Nanjundappa]

Introduced a new inline function _cairo_surface_is_xcb() as similar to
_cairo_surface_is_image() and used the same to check for xcb surface type

Signed-off-by: Ravi Nanjundappa <nravi.n at samsung.com>
---
 src/cairo-xcb-surface.c |   20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/cairo-xcb-surface.c b/src/cairo-xcb-surface.c
index c900edc..e3230c7 100644
--- a/src/cairo-xcb-surface.c
+++ b/src/cairo-xcb-surface.c
@@ -78,6 +78,22 @@ slim_hidden_proto (cairo_xcb_surface_create_with_xrender_format);
  * Since: 1.12
  **/
 
+
+/**
+ * _cairo_surface_is_xcb:
+ * @surface: a #cairo_surface_t
+ *
+ * Checks if a surface is an #cairo_xcb_surface_t
+ *
+ * Return value: %TRUE if the surface is an xcb surface
+ **/
+static inline cairo_bool_t
+_cairo_surface_is_xcb (const cairo_surface_t *surface)
+{
+    /* _cairo_surface_nil sets a NULL backend so be safe */
+    return surface->backend && surface->backend->type == CAIRO_SURFACE_TYPE_XCB;
+}
+
 cairo_surface_t *
 _cairo_xcb_surface_create_similar (void			*abstract_other,
 				   cairo_content_t	 content,
@@ -1432,7 +1448,7 @@ cairo_xcb_surface_set_size (cairo_surface_t *abstract_surface,
     }
 
 
-    if (abstract_surface->type != CAIRO_SURFACE_TYPE_XCB) {
+    if (! _cairo_surface_is_xcb (abstract_surface)) {
 	_cairo_surface_set_error (abstract_surface,
 				  _cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH));
 	return;
@@ -1486,7 +1502,7 @@ cairo_xcb_surface_set_drawable (cairo_surface_t *abstract_surface,
     }
 
 
-    if (abstract_surface->type != CAIRO_SURFACE_TYPE_XCB) {
+    if (! _cairo_surface_is_xcb (abstract_surface)) {
 	_cairo_surface_set_error (abstract_surface,
 				  _cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH));
 	return;
-- 
1.7.9.5