The Delegate Class: Brother where have you been?

Eureka! I've had a specific problem when writing AS2 classes for some while now. Namely, whenever I use code to make an interactive element (Let's say a movie clip that bounces away when you click on it), I have to nest the event handler's method. The problem is that this changes the scope and so the handler method can't access my classes base methods. The way I used to fix this was by making the methods I want to access Static, and accessible by anything in my class. The problem with this is that if I make a method static I have to make its variables static, and that can create a domino effect of making things static just to solve the original problem. This is pretty wordy so I'll post code that is easier to follow. Here's the old way I did things:

class SomeClass {
//constructor
public function SomeClass(someMC) {
//initialize object
initialize(someMC);
}
//this is static so the onPress method can access it
private static function doSomething() {
trace("Ok, I'm doing something");
}
private function initialize(someMC) {
trace(someMC);
//define what it needs to do when it loads
someMC.onPress = function(){
doSomething();
}
}
}

This is a very simple version of the problem. In reality the method my handler calls would probably be called by other methods and use variables that all would need to be made static. I knew this was not a good way to do things but until now I didn't know what else I could do.

Thanks to the Delegate class though, I'm able to specify the scope and therefore access the methods at my class' base level. Here's the same code as above but made with the delegate class:

//import the Delegate class
import mx.utils.Delegate;
class SomeClass{
//constructor
public function SomeClass(someMC) {
//initialize object
initialize(someMC);
}
private function pressHandler() {
trace("You pressed it.");
}
private function initialize(someMC) {
//define what it needs to do when it loads
someMC.onPress = Delegate.create(this, pressHandler);
}
}

Now there is no need for static so things are much easier when I need to tweak things later on.
While I was researching how to solve this problem I found other possible solutions but this was the one I understood best and was able to easily implement.

You can read all about the Delegate Class here: http://www.actionscript.org/resources/articles/205/1/The-Delegate-Class/Page1.html

This is all great to know but this problem has been resolved in Actionscript 3 thanks to its addEventListener method. Still if you're using on Flash Lite or like me your work doesn't want you to use AS3 until the Flash PLayer 9 adoption rate is higher you may find this very useful.

Good luck using the Delegate Class, and if you have other solutions I'd love to see what you have come up with.

Tip for Text in Flash

I was working my way through the hefty, 900+ page book Essential Actionscript 3.0 with the hopes of finishing it by the month's end when I learned something new. It has happened to me before that I wanted to use some dynamic text as part of something that rotated, skewed, or changed transparency. This never seemed to work so I always resorted to breaking the letters apart into graphics and abandoning the idea of dynamic text. Today, as I was reading page 705, I learned that dynamic text can be used in all these wonderful effects as long as you embed it. I did some tests and it is indeed true. Just make sure that you embedded all the symbols necessary, otherwise your text might be missing things when you render the swf.

You can see this in action in the new widget I've made for this blog, my Flickr Image viewer. This widget gets the 20 most recent pictures I've uploaded to my Flickr account and makes a cross-fading slide show with captions. As you can see I have embedded the font I use so the text as well as the images fade in and out. I made this widget with the help of the SWX technology created by Aral Balkan which allows Flash to easily access Flickr API (and others) easily without writing any server-side code.

Back in a strange new place

It's been a while but I've decided to keep this blog going. I've started working at a new job since my last post and moved to a new city. I'm very happy to say that my new job sent me to FlashForward 2007 in Boston, and I had a great time! There was so much there that inspired me that once I got home I felt overstimulated. There was too much for one post, so I'll be spreading things out over several posts.

Let me tell you about animation. The best things I learned for animation probably came from Chris Georgenes' talk. He went over some animation tricks and showed us some nice animation clips. I found the tips on lipsynching especially useful. Here's the gist:

1. Make a mouth graphic symbol (it must be a graphic).
2. In the symbol draw all the mouth shapes you want to use. You can use onion skinning to help you position the mouths.
3. Go back to the main timeline and add a keyframe, click on the mouth symbol, make sure single frame swapping is selected, and then enter the number of the frame with the mouth shape you want.
4. Continue as desired and that's it. You've learned single frame swapping.

You can watch a video tutorial of this as well as several other useful Flash animation tutorials by Hayk Manukyan at his blog: http://moolt.blogspot.com/2007_09_01_archive.html


I like this feature but it can get confusing remembering the frame numbers if you have many shapes. Once things ease up at work I think I will make a Flash extension for lipsynching that uses this feature but adds visuals so there will be no need to memorize the shapes.