as3代码实现调用摄像头

package {
    import flash.display.Sprite;
    import flash.media.Camera;
    import flash.media.Video;
    import flash.text.TextField;
    import flash.text.TextFieldAutoSize;
    import flash.utils.Timer;
    import flash.events.TimerEvent;
    import flash.events.ActivityEvent;

    public class main extends Sprite {
        private var myTextField:TextField;
        private var cam:Camera;
        private var t:Timer = new Timer(1000);

        public function main() {
            myTextField = new TextField();
            myTextField.background = true;
            myTextField.selectable = false;
            myTextField.autoSize = TextFieldAutoSize.LEFT;    
        
            cam = Camera.getCamera();
            
            if (!cam) {
                myTextField.text = "No camera is installed.";

            }else {
                myTextField.text = "Waiting to connect.";
                connectCamera(); 
            }

            addChild(myTextField);

            t.addEventListener(TimerEvent.TIMER, timerHandler);
        }

        private function connectCamera():void {
                var vid:Video = new Video(cam.width, cam.height);
                vid.x = 10;
                vid.y = 10;
                vid.attachCamera(cam);
                addChild(vid);    

                cam.setMotionLevel(5, 1000);
                cam.addEventListener(ActivityEvent.ACTIVITY, activityHandler);
        }

        private function activityHandler(e:ActivityEvent):void {
            if (e.activating == true) {
                t.start();    
            } else {
                myTextField.text = "Everything is quiet.";
                t.stop();
            }    
        }

        private function timerHandler(event:TimerEvent):void {
             myTextField.x = 10;
             myTextField.y = cam.height + 20;
             myTextField.text = "There is some activity. Level: " + cam.activityLevel;
        }
    }
}