Apply dissolve effect between two bitmaps

 使用AS脚本实现两幅图片之间的消解过渡。

 

package {
    import flash.display.Sprite;
    import flash.display.Bitmap;
    import flash.display.BitmapData;
    import flash.events.Event;
    import flash.geom.Point;

    public class Dissolve extends Sprite {
        private var _bitmap:BitmapData;
        private var _bitmap2:BitmapData;
        private var _image:Bitmap;
        private var _seed:Number;
        private var _pixelCount:int = 0;

        public function Dissolve(  ) 
        {
            //Create a white rectangle
            _bitmap = new BitmapData(stage.stageWidth,
                                  stage.stageHeight,
                                  false, 0xffffffff);
            //Create a Black rectangle
            _bitmap2 = new BitmapData(stage.stageWidth,
                                   stage.stageHeight,
                                   false, 0xff000000);
            //BitmapData object can not be displayed in the window,
            //yet Bitmap is accepted.
            _image = new Bitmap(_bitmap);
            //Show the white rectangel
            addChild(_image);
            //set a random number to dissolve between the two bitmap
            _seed = Math.random(  ) * 100000;
            //Begin dissolve when the frame show or say it when you enter the frame.
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }

        public function onEnterFrame(event:Event):void 
        {
            //Copy 1000 random points from bitmap2 which is the destine bitmap to bitmap
            //which is the start bitmap.
            _seed = _bitmap.pixelDissolve(_bitmap2,
                                       _bitmap.rect,
                                       new Point(  ),
                                       _seed,
                                       1000);
            _pixelCount += 1000;
            //If we have copied all the points in bitmap2,remove the event.
            if(_pixelCount > _bitmap.width * _bitmap.height) {
                removeEventListener(Event.ENTER_FRAME,
                                    onEnterFrame);
            }
        }
    }
}