Base class for animations that all get updated simultaneously each frame.

git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@163 ed5b42cb-e716-0410-a449-f6a68f950b19

src/as/com/threerings/flash/Animation.as

@@ -0,0 +1,101 @@
+package com.threerings.flash {
+
+import flash.display.DisplayObject;
+
+import flash.events.TimerEvent;
+
+import flash.utils.getTimer; // func import
+import flash.utils.Timer;
+
+public class Animation
+{
+    public function Animation ()
+    {
+    }
+
+    public function start () :void
+    {
+        addAnimation(this);
+    }
+
+    public function stop () :void
+    {
+        removeAnimation(this);
+//        didStop();
+    }
+
+    /**
+     * The primary working method for your animation.
+     */
+    protected function enterFrame () :void
+    {
+        // do your business here
+    }
+    
+    /**
+     * Add the specified anim to the list of active anims.
+     */
+    protected static function addAnimation (anim :Animation) :void
+    {
+        // add it
+        _anims.push(anim);
+
+        // set up the timer
+        if (!_timer) {
+            _timer = new Timer(10); // 10ms: will be limited by frame rate
+            _timer.addEventListener(TimerEvent.TIMER, frameHandler);
+        }
+        _timer.start();
+    }
+
+    /**
+     * Remove the specified anim.
+     */
+    protected static function removeAnimation (anim :Animation) :void
+    {
+        var dex :int = _anims.indexOf(anim);
+        if (dex != -1) {
+            _anims.splice(dex, 1);
+
+        } else {
+            Log.getLog(Animation).warning("Removing unknown Animation: " + anim);
+        }
+
+        if (_anims.length == 0) {
+            _timer.reset();
+        }
+    }
+
+    /**
+     * Handle our timer event.
+     */
+    protected static function frameHandler (event :TimerEvent) :void
+    {
+        _now = getTimer();
+        var an :Animation;
+        for (var ii :int = _anims.length - 1; ii >= 0; ii--) {
+            an = Animation(_anims[ii]);
+            if (isNaN(an._start)) {
+                an._start = _now;
+//                an.didStart();
+            }
+            an.enterFrame();
+        }
+
+        // and instruct the flash player to update the display list (now!)
+        event.updateAfterEvent();
+    }
+
+    /** Our own personal start stamp. */
+    protected var _start :Number = NaN;
+
+    /** The current timestamp, accessable to all animations. */
+    protected static var _now :Number;
+
+    /** All the currently running animations. */
+    protected static var _anims :Array = [];
+
+    /** The timer we use to manage our animations. */
+    protected static var _timer :Timer;
+}
+}