Hello. My name is Václav Vančura.

Dummy Tween Plugin

A somewhat different approach to periodical calling of a method. This time with TweenLite/TweenMax by Greensock

As I said before, last few months I’ve been working for Falanxia.com, where I help to develop social games in Flash (and more platforms coming). I was not very happy with the way how to periodically call a method:

var timer:Timer = new Timer(10, 100); // call a method 100 times with 10 ms delay)
timer.addEventListener(TimerEvent.TIMER, method);
timer.start();

Is there a shorter approach to do the same thing? While we already use TweenLite/TweenMax a lot, I thought there has to be a plugin which should handle this task (no, I don’t need TweenLite.delayedCall(). Well, nope, there’s not. But sure it can be handled this way:

var tweenObj:Object = {pass:0};
TweenLite.to(tweenObj, 1, {ease:Liner.easeNone, onUpdate:method}); // 100 * 10 ms = 1 second

IMHO this way is a bit cumbersome and you need to create an Object to be tweened. I came up with a simple TweenLite plugin to do the job:

/*
 * Falanxia Utilitaris.
 *
 * Copyright (c) 2010 Falanxia (http://falanxia.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.falanxia.utilitaris.plugins {
    import com.greensock.*;
    import com.greensock.plugins.*;



    /**
     * Dummy tween plugin.
     *
     * @author Vaclav Vancura @ Falanxia a.s. vaclav@falanxia.com
     * @author Falanxia (falanxia.com
     * @since 1.0
     */
    public class DummyTweenPlugin extends TweenPlugin {


        public static const API:Number = 1.0;

        protected var _target:Object;



        /**
         * Constructor.
         */
        public function DummyTweenPlugin() {
            super();
            this.propName = "dummy";
            this.overwriteProps = ["dummy"];
        }



        /**
         * Tween initialization.
         * Gets called when any tween of the special property begins. Store any
         * initial values and/or variables that will be used in the "changeFactor"
         * setter when this method runs.
         * @param target Target object of the TweenLite instance using this plugin
         * @param value The value that is passed in through the special property
         * @param tween The TweenLite or TweenMax instance using this plugin
         * @return If the initialization failed, it returns false. Otherwise true.
         * It may fail if, for example, the plugin requires that the target be a
         * DisplayObject or has some other unmet criteria in which case the plugin
         * is skipped and a normal property tween is used inside TweenLite
         */
        override public function onInitTween(target:Object, value:*,
            tween:TweenLite):Boolean {
            return true;
        }
    }
}

How to use it?

TweenPlugin.activate([DummyTweenPlugin]);
// first you need to activate the plugin, but only once in the whole app

TweenLite.to(this, 1.0, {dummy:{}, onUpdate:method});

This way there’s no need to create an Object variable. I think it’s a bit simpler. Actually this article took much more time to write than to code the DummyTweenPlugin.