renderer: expose CoglOutputs

This adds a cogl_renderer_foreach_output() function that can be used to
iterate the display outputs for a particular renderer.

This also updates cogl-info to use this new api so it can dump out all
the output information.

Reviewed-by: Owen W. Taylor <otaylor@fishsoup.net>

(cherry picked from commit a2abf4c4c1fd5aeafd761f965d07a0fe9a362afc)

cogl/cogl-renderer.h

@@ -31,6 +31,7 @@
 #include <cogl/cogl-types.h>
 #include <cogl/cogl-onscreen-template.h>
 #include <cogl/cogl-error.h>
+#include <cogl/cogl-output.h>
 
 COGL_BEGIN_DECLS
 
@@ -383,6 +384,39 @@ cogl_renderer_set_driver (CoglRenderer *renderer,
 CoglDriver
 cogl_renderer_get_driver (CoglRenderer *renderer);
 
+/**
+ * CoglOutputCallback:
+ * @output: The current display output being iterated
+ * @user_data: The user pointer passed to
+ *             cogl_renderer_foreach_output()
+ *
+ * A callback type that can be passed to
+ * cogl_renderer_foreach_output() for iterating display outputs for a
+ * given renderer.
+ *
+ * Since: 1.14
+ * Stability: Unstable
+ */
+typedef void (*CoglOutputCallback) (CoglOutput *output, void *user_data);
+
+/**
+ * cogl_renderer_foreach_output:
+ * @renderer: A connected #CoglRenderer
+ * @callback: A #CoglOutputCallback to be called for each display output
+ * @user_data: A user pointer to be passed to @callback
+ *
+ * Iterates all known display outputs for the given @renderer and
+ * passes a corresponding #CoglOutput pointer to the given @callback
+ * for each one, along with the given @user_data.
+ *
+ * Since: 1.14
+ * Stability: Unstable
+ */
+void
+cogl_renderer_foreach_output (CoglRenderer *renderer,
+                              CoglOutputCallback callback,
+                              void *user_data);
+
 COGL_END_DECLS
 
 #endif /* __COGL_RENDERER_H__ */