AS3 Serialization and Deserialization: ByteArray BitmapData registerClassAlias September 12, 2007

Grr. Flash's registerClassAlias does not work with BitmapData (I wonder ?), so while you can save it to the ByteArray and wherever that can go... you can't get it back! As BitmapData complains about the constructor getting no args, presumeably that memory allocation is fixed upon the constructor.
This means you'll have to roll your own, which isn't too hard but it when having the BitmapData as members of other classes it might be a pain as each will have to serialize/deserialize the BitmapData using the IExternalizable.
Another option might have been overridding, but while BitmapData can be extended there isn't a no arg constructor, so the constructor can't really be overridden efficetively. A Proxy could be created for this.
Andrew has a good workaround, iterating over the pixels, though I've opted to write the width and height into the stream as well. You can use writeObject for the height and widht without problems (versus writing writeInt)
For additional details and others experiencing this problem: search terms "registerClassAlias BitmapData" "deserialize Bitmapdata"

• http://www.google.com/search?q=deserialize+BitmapData&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
• http://www.adobe.com/cfusion/webforums/forum/messageview.cfm?catid=641&threadid=1255888#4547075
• http://osflash.org/pipermail/red5_osflash.org/2007-April/011091.html

Solutions

• [1] http://www.cynergysystems.com/blogs/blogs/andrew.trice/BitmapData/SharedDesktop/srcview/
• [2] http://www.barncar.com/writejpg.mxml (sample code using corelib to save as Jpg)
• http://www.bytearray.org/?p=90 (a more flexible snapshot of video/swf to jpg using corelib, which is a completely different solution path)
• corelib is here http://code.google.com/p/as3corelib/

NOTE:

if you do need to use registerClassAlias you can do this trick:

private static const REG:* = registerClassAlias("reflection.IntrospectableObj",IntrospectableObj);