Animating Dynamic MovieClips in AS3 - Page 1
       by kirupa  |  28 May 2007

It is fairly straightforward to animate in Flash using the timeline. With a little knowledge of programming, you can even animate movie clips that exist on your stage. What is more tricky, though, is animating movie clips that neither use the timeline nor exist on the stage. These movie clips exist solely in your Library, and this tutorial will cover how to use code to animate them.

For example, click around the following blue rectangle to see circles fade in and fade out at the location of your click:

The circles are added to the stage and animated only when your mouse is clicked, and in this tutorial, you will learn how to animate content drawn and stored in your library.

Let's Get Started
First, you will need to create a movie clip that will be loaded dynamically. For this article, simply create a solid blue circle movie clip and, in the Library, give it the class name BlueCircle. If you are not sure how to do that, the following instructions will help you out.

If you already know how to do create a circle stored in the Library with the class name BlueCircle, skip on over to the next page where you'll see the code.

Creating the BlueCircle MovieClip:
The following instructions explain how to setup your movie and specify the blue circle that will be loaded dynamically.

  1. First, create a new animation in Flash CS3. From the Properties panel, click the button next to the Size text and set the animation's width and height to 300 pixels by 200 pixels respectively:

[ set your animation's width/height to 300 by 200 ]

  1. Now that our stage's width and height have been setup just the way we want, let's draw a circle. Using the Circle tool, draw a circle with a blue solid-fill color:

[ draw a blue, solid, filled circle ]

  1. Make sure your circle has been selected and press F8 or go to Modify | Convert to Symbol. The Convert to Symbol window will appear. For name, enter circle and make sure the Movie Clip option has been selected:

[ give your symbol the name circle and make sure it is also set to be a movie clip ]

Do not hit OK just yet. Let's make some more modifications.

  1. From the same Convert to Symbol window, find the area marked Linkage. If you do not see the Linkage area, press the Advanced button to display it. Check the box that says Export for Actionscript. A few lines above that, in the Class field, replace whatever text is displayed (probably circle) with the text BlueCircle:

[ check 'Export for ActionScript and enter BlueCircle for your class ]

The Base class field will automatically be populated for you, but if it hasn't, make sure to enter flash.display.MovieClip as shown in the above image.

  1. Press OK to close the Convert to Symbol window. After you have pressed OK, you will see your Library display your newly created symbol:

[ your circle in your Library ]

If you do not see your Library, press Ctrl + L to display it.

  1. At this point, your circle movie clip is stored in the Library, and you have a copy of that same clip on your stage right now. Select the blue circle movie clip located on your stage and delete it by pressing the Delete key. You should now have a blank stage with nothing in it.

Ok, you should see a blank stage with your library displaying the circle movie clip with the class name BlueCircle. Right now, nothing is really being done. We'll change that on the next page when you add the code.

Onwards to the next page!

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