1 files changed, 68 insertions, 0 deletions
diff --git a/src/undo-stack-observer.h b/src/undo-stack-observer.h
new file mode 100644
index 000000000..f9e3d9dd0
--- /dev/null
+++ b/src/undo-stack-observer.h
@@ -0,0 +1,68 @@
+/**
+ * Undo stack observer interface
+ *
+ * Observes undo, redo, and undo log commit events.
+ *
+ * Authors:
+ * David Yip <yipdw@rose-hulman.edu>
+ *
+ * Copyright (c) 2005 Authors
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#ifndef __UNDO_COMMIT_OBSERVER_H__
+#define __UNDO_COMMIT_OBSERVER_H__
+
+namespace Inkscape {
+
+namespace XML {
+
+class Event;
+
+}
+
+/**
+ * Observes changes made to the undo and redo stacks.
+ *
+ * More specifically, an UndoStackObserver is a class that receives notifications when
+ * any of the following events occur:
+ * <ul>
+ * 	<li>A change is committed to the undo stack.</li>
+ * 	<li>An undo action is made.</li>
+ * 	<li>A redo action is made.</li>
+ * </ul>
+ *
+ * UndoStackObservers should not be used on their own.  Instead, they should be registered
+ * with a CompositeUndoStackObserver.
+ */
+class UndoStackObserver {
+public:
+	UndoStackObserver() { }
+	virtual ~UndoStackObserver() { }
+
+	/**
+	 * Triggered when the user issues an undo command.
+	 *
+	 * \param log Pointer to an XML::Event describing the undone event.
+	 */
+	virtual void notifyUndoEvent(XML::Event* log) = 0;
+
+	/**
+	 * Triggered when the user issues a redo command.
+	 *
+	 * \param log Pointer to an XML::Event describing the redone event.
+	 */
+	virtual void notifyRedoEvent(XML::Event* log) = 0;
+
+	/**
+	 * Triggered when a set of transactions is committed to the undo log.
+	 *
+	 * \param log Pointer to an XML::Event describing the committed events.
+	 */
+	virtual void notifyUndoCommitEvent(XML::Event* log) = 0;
+};
+
+}
+
+#endif