How to create irregular shape mask

Question

I'm trying to make a mask with bitmaps, i.e. has such a shape below. Here my image mask:

All, in above image, is not white is transparent. So applying a mask she cuts a rectangle instead of this form. Is there any way to implement it? Primitives will hardly make such a mask.

Here my source:

package
{
    import flash.display.Bitmap;
    import flash.display.Sprite;

    [SWF(width="960", height="640", frameRate="60", backgroundColor="0x4a4137")]
    public class Main extends Sprite
    {
        [Embed(source="jack.jpg")]
        private var PhotoImg:Class;

        [Embed(source="faceArea.png")]
        private var FaceAreaImg:Class;

        private var _imageBox:Sprite;

        public function Main()
        {
            createMask();
        }

        private function createMask():void
        {
            var img:Bitmap = new PhotoImg();
            _imageBox = new Sprite();
            _imageBox.x = 0;
            _imageBox.y = 0;
            _imageBox.addChild(img);
            addChild(_imageBox);

            var faceArea:Bitmap = new FaceAreaImg();
            faceArea.x = 50;
            faceArea.y = 50;
            addChild(faceArea);

            _imageBox.mask = faceArea;
        }
    }
}

Answer 1

Hi skyboy

If you want to make masking with transparent bitmaps, you have to make the cacheAsBitmap property of the two DisplayObjects to true.

try:

_imageBox.cacheAsBitmap = true;
faceArea.cacheAsBitmap = true;