Asynchronously encode BitmapData objects into image file format
ActionScript JavaScript CSS
Latest commit 31f26a4 Aug 28, 2013 Lee Burrows Added EOL to readme

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:

    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...
            // 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.