--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/observer.h	Mon Aug 18 01:59:26 2008 +0800
@@ -0,0 +1,71 @@
+#ifndef __OBSERVER_H_
+#define __OBSERVER_H_
+
+#include "tools.h"
+
+typedef struct _event event_t;
+typedef struct _observer observer_t;
+typedef struct _subject subject_t;
+typedef struct _mouse_event mouse_event_t;
+typedef struct _ob_factory ob_factory_t;
+typedef void (*evt_handler)(event_t *event, void *arg);
+
+struct _event {
+    int type;
+    subject_t *tgt, *cur_tgt;
+};
+
+struct _observer {
+    evt_handler hdr;
+    void *arg;
+    observer_t *next;
+};
+
+struct _subject {
+    int obj_type;
+    void *obj;
+    int flags;
+    STAILQ(observer_t) observers;
+};
+#define SUBF_STOP_PROPAGATE 0x1
+
+enum {OBJT_GEO, OBJT_COORD};
+
+struct _mouse_event {
+    event_t event;
+    int x, y;
+    int button;
+};
+
+/*! \brief Observer factory.
+ *
+ * It provides functions for allocation of subject and observer objects,
+ * and strategy function for getting the subject of parent coord object.
+ */
+struct _ob_factory {
+    subject_t *(*subject_alloc)(ob_factory_t *factory);
+    void (*subject_free)(ob_factory_t *factory, subject_t *subject);
+    observer_t *(*observer_alloc)(ob_factory_t *factory);
+    void (*observer_free)(ob_factory_t *factory, observer_t *observer);
+    /*! This is a strategy function to get subjects of parents. */
+    subject_t *(*get_parent_subject)(ob_factory_t *factory,
+				     subject_t *cur_subject);
+};
+
+enum {EVT_MOUSE_OVER, EVT_MOUSE_OUT, EVT_MOUSE_MOVE,
+      EVT_MOUSE_BUT_PRESS, EVT_MOUSE_BUT_RELEASE};
+
+extern subject_t *subject_new(ob_factory_t *factory,
+			      void *obj, int obj_type);
+extern void subject_free(ob_factory_t *factory, subject_t *subject);
+extern void subject_notify(ob_factory_t *factory,
+			   subject_t *subject, event_t *evt);
+extern observer_t *subject_add_observer(ob_factory_t *factory,
+					subject_t *subject,
+					evt_handler hdr, void *arg);
+extern void subject_remove_observer(ob_factory_t *factory,
+				    subject_t *subject,
+				    observer_t *observer);
+
+
+#endif /* __OBSERVER_H_ */