Managing Movie Clip Instances - Page 1
       by kirupa  |  7 September 2008

For many types of projects, you will be instantiating movie clips from your library and displaying them on your stage. Instantiating is a fancy word word for creating a copy of or duplicating. An earlier tutorial covers just how you would do that. One thing that the earlier tutorial does not cover is how to actually manage those instantiated movie clips. Once a movie clip has found its way into your stage, how can you work with it later? That is where this tutorial comes in.

Click on the following blob of circles to see an example where, each time you click, the circles that make up the blob disappear and are replaced with new circles:

This is done by me storing a reference to each movie clip and deleting them later. In this tutorial, let's learn how to do that.

Let's Get Started
What you are going to do is create a circle movie clip whose class name is BlueCircle. If you need further instructions on how to do that, the following instructions will help you out. Otherwise, skip over to the next page where we introduce the code and explain what is going on:

  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, now we are in a good spot, for you have your library setup. In the next page, let's add the code and explain what was done to keep track of the newly added movie clips.

Onwards to the next page.

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