Saving BitmapData to File

Encoding bitmap data to a file can be a slow process when using AS3 operations. This extension provides functionality to use the native PNG and JPG encoders to save BitmapData to a file which greatly increases the speed of saving images.

Most of the operations provided by this ANE can be performed synchronously or asynchronously. Synchronous operations may block your UI if you are dealing with large images so we suggest you use the asynchronous versions wherever possible.

var image:Bitmap = new SampleImage() as Bitmap;
var f:File = File.applicationStorageDirectory.resolvePath("test.png");

Image.service.addEventListener( ImageEvent.SAVE_COMPLETE, saveBitmapDataAsync_completeHandler );
Image.service.addEventListener( ImageEvent.SAVE_ERROR, saveBitmapDataAsync_errorHandler );

var success:Boolean = Image.service.saveBitmapDataAsync( image.bitmapData, f.nativePath, ImageFormat.PNG );

When the save operation completes you will receive either an ImageEvent.SAVE_COMPLETE event or an ImageEvent.SAVE_ERROR event:

function saveBitmapDataAsync_completeHandler( event:ImageEvent ):void
{
    trace( "Save successfully: " + event.identifier );
}

function saveBitmapDataAsync_errorHandler( event:ImageEvent ):void
{
    trace( "Save failed: " + event.identifier );
}

Caching Internally

In order to avoid crashes when AIR garbage collects the Bitmap Data we make a copy of the image and use this cached version internally.

If you pass a local variable to the saveBitmapDataAsync function and we don't cache the image data, AIR isn't aware of the ANE reference and may dealloc the memory we are using to save the image. So by default we cache the image internally.

This can have a small affect on the performance as we need to create a copy of the image.

If you are concerned about the speed of this function you should try to set cacheBitmapInternally to false and make sure that you hold onto a reference to your bitmap data, for example, as a class variable.

// Class variable will hold reference to bitmap
private var image:Bitmap;


private function saveBitmap():void 
{
    Image.service.addEventListener( ImageEvent.SAVE_COMPLETE, saveBitmapDataAsync_completeHandler );
    Image.service.addEventListener( ImageEvent.SAVE_ERROR, saveBitmapDataAsync_errorHandler );

    // Set cacheBitmapInternally to false
    var success:Boolean = Image.service.saveBitmapDataAsync( image.bitmapData, f.nativePath, ImageFormat.PNG, false );
}

private function saveBitmapDataAsync_completeHandler( event:ImageEvent ):void
{
    trace( "Save successfully: " + event.identifier );
    // dispose image if required.
}

private function saveBitmapDataAsync_errorHandler( event:ImageEvent ):void
{
    trace( "Save failed: " + event.identifier );
    // dispose image if required.
}

Caching Internally​

Caching Internally