Asynchronous Image Encoders

ActionScript 3 classes for asynchronously encoding BitmapData source into image file formats

Encodes BitmapData objects over multiple frames to avoid freezing the UI. Ideally suited for mobile AIR where ActionScript Workers are unavailable.

Specify milliseconds per frame to allocate to encoding. Stop processing at any time.

Current supported file formats:

• .JPG
• .PNG
• .BMP

Others can be added by sub-classing AsyncImageEncoderBase to implement asynchronous processing. See ASDocs for further details on implementing your own encoders.

A simple usage example:

package
{
	import com.leeburrows.encoders.AsyncPNGEncoder;
	import com.leeburrows.encoders.supportClasses.AsyncImageEncoderEvent;
	import com.leeburrows.encoders.supportClasses.IAsyncImageEncoder;
	import flash.display.BitmapData;
	import flash.display.Sprite;

	public class PNGEncoderExample extends Sprite
	{
		private var encoder:IAsyncImageEncoder;

		public function PNGEncoderExample()
		{
			//generate a BitmapData object to encode
			var myBitmapData:BitmapData = new BitmapData(1000, 1000, true, 0x80FF9900);
			//create a new PNG encoder
			encoder = new AsyncPNGEncoder();
			//add progress and complete listeners
			encoder.addEventListener(AsyncImageEncoderEvent.PROGRESS, encodeProgressHandler);
			encoder.addEventListener(AsyncImageEncoderEvent.COMPLETE, encodeCompleteHandler);
			//start encoding for 20 milliseconds per frame
			encoder.start(myBitmapData, 20);
		}

		private function encodeProgressHandler(event:AsyncImageEncoderEvent):void
		{
			//trace progress
			trace("encoding progress:", Math.floor(event.percentComplete)+"% complete");
		}

		private function encodeCompleteHandler(event:AsyncImageEncoderEvent):void
		{
			encoder.removeEventListener(AsyncImageEncoderEvent.PROGRESS, encodeProgressHandler);
			encoder.removeEventListener(AsyncImageEncoderEvent.COMPLETE, encodeCompleteHandler);
			//trace size of result
			trace("encoding completed:", encoder.encodedBytes.length+" bytes");
			//do something with the bytes...
			//..save to filesystem?
			//..upload to server?
			//..set as source for flex Image component?
		}
	}
}

Version History

• v1.0.1

  • Initial build.

• v1.0.2

  • Fixed issue #001 : Validate start() BitmapData Argument.
  • Fixed issue #002 : Consolidate Events.
  • Fixed issue #003 : Private _encodedBytes Property Exposed Via Reference.

• v1.0.3

  • ASDocs inserted into SWC to facilitate IDE code hinting.

• v1.0.4

  • Added dispose() method.
  • Fixed issue #004 : Unnecessary memory retention.