ActionScript for Flash MX: The Definitive Guide, Second Edition

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Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Timeline and Clip Event Loops

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Note that step 12 isn’t mandatory, but it gives us more control over our loop. By giv-

ing our process instance a name, we can stop and start our loop by starting and stop-

ping the playback of the instance, like this:

processMoveBall_mc.play( );

processMoveBall_mc.stop( );

Note that in this example, processMoveBall_mc and ball_mc must both exist on the

main timeline for as long as the loop is supposed to work. If we want to make the

code more portable, we can use a relative reference to our

ball_mc clip in the process

symbol:

_parent.ball_mc._x += 10;

Timeline loops can’t loop on a single frame. That is, if we place a

gotoAndPlay(5) function on frame 5 of a movie, the function will be

ignored. The Flash Player realizes that the playhead is already on

frame 5, and it simply does nothing.

You’ll find the sample timeline loop and empty-clip loop .fla files in the online Code

Depot.

Movie Clip onEnterFrame( ) Loops

Timeline loops are effective but not necessarily elegant. We can use an event handler

on a movie clip to achieve the same results as a timeline loop but with more flexibil-

ity (just try to follow along with this example, or see Chapter 10 for details on movie

clip event handlers).

When placed on a movie clip, an onEnterFrame( ) event handler causes ...