[udaaff]

import flash.display.BitmapData;
import flash.geom.*
 
// На сцене лежат два мувика mask и image.
mask._visible = false;
image._visible = false;
 
var imageBitmap:BitmapData = new BitmapData(image._width, image._height, true, 0x00000000)
imageBitmap.draw(image);
 
var maskBitmap:BitmapData = new BitmapData(mask._width, mask._height, true, 0x00000000);
maskBitmap.draw(mask);
 
var maskedBitmap:BitmapData = new BitmapData(mask._width, mask._height, true, 0x00000000);
 
maskedBitmap.copyPixels(imageBitmap, 
        new Rectangle(mask._x, mask._y, mask._width, mask._height), 
        new Point(0, 0), maskBitmap, new Point(0, 0));
 
// Выводим результат
var result:MovieClip = createEmptyMovieClip("result", 0);
result.attachBitmap(maskedBitmap, 0);