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actionscript-3flashpreloaderflash-cs6

Internal AS3 preloader & stage issues

I need to create a single SWF with no external files, so I'm trying to add an internal preloader to my Flash project which has [embed] assets. I know [embed] causes problems with preloaders because it puts the assets on frame 1. I have tried the solutions recommended in these posts, where you set the document class to your preloader class:

Preloader for SWF with embed bytearray

How to create Preloader in AS3

I can get it to work, but ONLY if I comment out any lines of code that involve the stage, otherwise I get an "Error #1009: Cannot access a property or method of a null object reference." Those lines are essential though, so does anyone know how to fix those errors with the stage?

Solution

  • You haven't posted your code or your fla, so all I can do is share what works for me.

    First, I wouldn't use Embed. Instead, use a swc. I have found that Embed can be unreliable as far as actually getting the entire asset in there (at least when publishing with Flash Builder + Flash Pro, which is my workflow).

    Once you have your assets in a swc, try the following steps:

    1. Set your export frame to Frame 10 (or any frame other than 1--I like frame 10 because then you can read the label that says "Preloader")
    2. Put your actual content on frame 11. You can structure this a lot of ways. Since I program to Interfaces, I give whatever is on frame 11 an instance name and then use a setter to determine that my "first thing" has been placed on stage. I can get away with this because my main Document Class just knows the definition of the Interface, not the full implementation of the Class, so the Class does not need to load for the main Document Class to work. You probably aren't truly using the timeline and probably didn't program to interfaces, so you'll probably just set the base class of the symbol that's on frame 11 to the main logic of whatever you're trying to do.
    3. Put your preloader graphics in Frame 1. I'm not sure why your stage references are so important. I, personally, don't use any logic in the preloader. Instead, I use a spinner that spans frames 1-10 (plus the word "Loading...". The spinner just spins while the classes load. The embed frame acts as a temporary "stop" that just holds the timeline back until those classes have been loaded. Once the classes have been loaded, the timeline will act like you called play() on it. So it really can be that simple. If you need it to be more complicated, give one of your preloader graphics an instance name and set up a getter/setter pair for it, then use the setter to trigger your logic that accesses the stage. You are pretty much guaranteed to have a valid stage at that point.

    Word of warning: if you did make use of the timelime, you will get strange results if you try to jump to a frame that isn't loaded yet, so make sure to check to see if a given frame is loaded if it's near the end of your main timeline and your main timeline is heavy with assets before calling goToAndPlay() or goToAndStop().

    Some references that might help you further: