More.

Made ObserverList work with a passed-in function, actionscript style. I might reconsider some earlier decisions to go away from ObserverList. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3952 542714f4-19e9-0310-aa3c-eee0fc999fb1
2006-03-16 02:11:27 +00:00
parent 3325b1d7a3
commit 03d94291db
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+//
+// $Id: PlaceView.java 3098 2004-08-27 02:12:55Z mdb $
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.crowd.client {
+
+import com.threerings.crowd.data.PlaceObject;
+
+/**
+ * This interface provides a convenient means for decoupling user
+ * interface components that interact with a place object and that need to
+ * keep themselves up to date when the client moves from place to place.
+ *
+ * <p> In general, such components need to know when the client is about
+ * to enter a place so that they can subscribe if necessary or at least
+ * extract information about the place. They also need to know when a
+ * client has left a place so that they can unsubscribe and clean up after
+ * themselves. This is the information that the place view interface makes
+ * available to them in a decoupled way.
+ *
+ * <p> The part of the client implementation that is responsible for the
+ * main user interface can act as a location observer, and it can make use
+ * of {@link PlaceViewUtil} to dispatch notification of place changes to
+ * every <code>PlaceView</code> implementing user interface element in the
+ * user interface hierarchy with calls to {@link
+ * PlaceViewUtil#dispatchWillEnterPlace} and {@link
+ * PlaceViewUtil#dispatchDidLeavePlace}. These functions traverse the UI
+ * hierarchy (starting with the element provided which would generally be
+ * the top-level UI element, and dispatch calls to {@link #willEnterPlace}
+ * and {@link #didLeavePlace} respectively on any UI element they find
+ * that implements <code>PlaceView</code>.
+ *
+ * <p> By doing this, the client code can simply create place-sensitive
+ * user interface elements and stick them in the user interface and
+ * essentially forget about them, knowing that they will all be notified
+ * of place entering and exiting by virtue of the single dispatching
+ * calls. It is useful to note that place-sensitive user interface
+ * elements will also generally need a reference to the {@link
+ * com.threerings.crowd.util.CrowdContext} derivative in use by
+ * the client, but those are best supplied at construct time.
+ */
+public interface PlaceView
+{
+    /**
+     * Called when the client has entered a place and is about to display
+     * the user interface for that place.
+     *
+     * @param plobj the place object that was just entered.
+     */
+    function willEnterPlace (plobj :PlaceObject) :void;
+
+    /**
+     * Called after the client has left a place and needs to clean up
+     * after the user interface that was displaying that place.
+     *
+     * @param plobj the place object that was just left.
+     */
+    function didLeavePlace (plobj :PlaceObject) :void;
+}
+}