AS3 BitmapData源代码

A mobile AIR app needs to send a large image to the back end for later display in a web page. It takes for ever for PNGEncoder in the AIR app to complete, so the idea is to convert the image data to a ByteArray, compress it and send it to the PHP backend where it is saved as PNG by the PHP code. So I'm looking to port PNGEncoder.as and BitmapData class to PHP to accomplish this. I found PNGEncoder.as in as3corelib but can't find source for BitmapData class that it uses. So the questions are
1. Is there code out there that does what I'm trying to do?
2. Where can I find BitmapData source code?
3. Is there another way to accomplish this that I'm missing?

Note1. I realize that I can decompile airglobal.swf where BitmapData resides, but looking for a cleaner way
Note2. I'm aware of AMFPHP but it does not support BitmapData type
Thanks Andy

I see two solutions to this issue.

First, you can consider using a Worker to do just the conversion and sending routine, because image conversion is a pretty standalone and straightforward task to offload, and since most modern devices have more than one core anyway, it's better to put the hardware to work on the client rather than on server. Of course, you will have to take some measures to provide the worker instance with required data and to properly upload the image (cookies might not be handled well in a worker), but this approach is generally cleaner and requires no server side alterations.

The second approach is to use BitmapData.getPixels() to convert a region of pixels into a sequence of bytes, then send them unaltered to the server for conversion. Be warned however, the amount of data in a raw bitmap can be too large for the server to accept, you are looking to no less than 4 bytes per pixel, as bitmaps in AS3 are 32-bit. You can use a server side image encoder to convert raw data on the server after uploading.