Trainers Talk Tech

One of the most frustrating things for me to learn in AS 3.0 was being able to find my movie clips in the code. I usually work on a single Flash timeline with lots of nested movie clips that make up my elearning: Frame 1 has an intro movie clip, Frame 2 introduces the course, etc.

My frustration with AS3.0 is that I couldn't figure out how to control my main movie from within my nested movie symbol. For example, in Frame 1, my intro movie plays, and then ends on a screen that explains the learning objectives. There is a big "Start the Training" button, and when the user clicks on it, the ROOT of the Flash movie advances to frame 2, where a new movie symbol plays.

Not that hard right? Old ActionScript code:

_root.play();

Not any more. I'm stubborn...I want AS 3.0 to work like AS 2.0. Suck it up buttercup, it won't. The reality is AS 3.0 doesn't see the "stage" or even the "timeline", relative to the objects. Think of it this way...in AS 1.0 and 2.0, objects added to your movie existed on the timeline, and Flash knew where they were at based on where on the timeline you placed them. They were "happyBall instance on frame 1 of the main timeline(root)."

In AS 3.0, movie clips just "are". Very zen like, I know, but in AS 3.0, they are defined as themselves. It doesn't matter where they are on the timeline - their identity is not connected to where they are placed. So, trying to add "root" to an AS 3.0 object is like trying to tell a book to go back to the printing press where it was created. Can't do it on its own - it has no awareness of its location.

After searching around the web, and finding a ton of different solutions (some of which seemed overly complicated, especially the ones that said to replace

_root

with just

root

...doesn't work...nice try), the kind developers at Yahoo found a working solution. It goes back to the day when you were able to identify anything based on its location, relative to the root. The code looks like this:

MovieClip(this.root)

So, in our example, in the movie clip, we have a button that advances to the next frame of the main timeline. There is a movie with some text and a button (named clickMe) in it. In the Movie clip, you would add this code:

clickMe.addEventListener(MouseEvent.CLICK, goClickMe);

function goClickMe(event:MouseEvent):void {
	MovieClip(this.root).play();
}

You can control the main timeline from within movie clips using that bit of code.

I hope this helps you as much as it helped me. Maybe its no longer a best practice to embed ActionScript in movies that control other things besides that movie symbol, but for a guy like me that wants to move from AS 2.0 to 3.0 quickly, I'm going to hang my hat on these little tricks to help me rapidly develop my projects.

Oh...and if you want to download a sample to see this in action click here. Its a Flash CS4/AS 3.0 file that shows you the controls I'm talking about.