docs: Add custom ClutterActor example which uses composition

doc/cookbook/examples/cb-button.h

@@ -0,0 +1,72 @@
+/* inclusion guard */
+#ifndef __CB_BUTTON_H__
+#define __CB_BUTTON_H__
+
+/* include any dependencies */
+#include <clutter/clutter.h>
+
+/* GObject implementation */
+
+/* declare this function signature to remove compilation errors with -Wall;
+ * the cb_button_get_type() function is actually added via the
+ * G_DEFINE_TYPE macro in the .c file
+ */
+GType cb_button_get_type (void);
+
+/* GObject type macros */
+#define CB_TYPE_BUTTON             (cb_button_get_type ())
+#define CB_BUTTON(obj)             (G_TYPE_CHECK_INSTANCE_CAST ((obj), CB_TYPE_BUTTON, CbButton))
+#define CB_IS_BUTTON(obj)          (G_TYPE_CHECK_INSTANCE_TYPE ((obj), CB_TYPE_BUTTON))
+#define CB_BUTTON_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), CB_TYPE_BUTTON, CbButtonClass))
+#define CB_IS_BUTTON_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), CB_TYPE_BUTTON))
+#define CB_BUTTON_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), CB_TYPE_BUTTON, CbButtonClass))
+
+/*
+ * Private instance fields; see
+ * http://www.gotw.ca/gotw/024.htm for the rationalse
+ */
+typedef struct _CbButtonPrivate    CbButtonPrivate;
+typedef struct _CbButton           CbButton;
+typedef struct _CbButtonClass      CbButtonClass;
+
+/* object structure */
+struct _CbButton
+{
+  /*<private>*/
+  ClutterActor parent_instance;
+
+  /* structure containing private members */
+  /*<private>*/
+  CbButtonPrivate *priv;
+};
+
+/* class structure */
+struct _CbButtonClass
+{
+  /* signals */
+  void (* clicked) (CbButton *button);
+
+  /*<private>*/
+  ClutterActorClass parent_class;
+};
+
+/* public API */
+
+/* constructor - note this returns a ClutterActor instance */
+ClutterActor *cb_button_new (void);
+
+/* getter */
+G_CONST_RETURN gchar * cb_button_get_text (CbButton *self);
+
+/* setters - these are wrappers round functions
+ * which change properties of the internal actors
+ */
+void cb_button_set_text (CbButton *self, const gchar *text);
+
+void cb_button_set_background_color (CbButton *self,
+                                     const ClutterColor *color);
+
+void cb_button_set_text_color (CbButton *self,
+                               const ClutterColor *color);
+
+#endif /* __CB_BUTTON_H__ */