onClipEvent (load) {
        // 初始化瓢虫移动的速度
        speed = 10;
}
onClipEvent (enterFrame) {//以影片剪辑的帧频连续触发该动作。
        // 垂直/水平方向
        if (Key.isDown(Key.LEFT) ) {//按下左键
                _x -= speed;
                _rotation = 270;
        }
        if (Key.isDown(Key.RIGHT) ) {//右
                _x += speed;
                _rotation = 90;
        }
        if (Key.isDown(Key.UP)) {//上
                _y -= speed;
                _rotation = 0;
        }
        if (Key.isDown(Key.DOWN) ) {//下
                _y += speed;
                _rotation = 180;
        }
        // 倾斜方向
        if (Key.isDown(Key.LEFT) & Key.isDown(Key.UP)) {
                _rotation = 315;
        }
        if (Key.isDown(Key.RIGHT) & Key.isDown(Key.UP)) {
                _rotation = 45;
        }
        if (Key.isDown(Key.LEFT) & Key.isDown(Key.DOWN)) {
                _rotation = 225;
        }
        if (Key.isDown(Key.RIGHT) & Key.isDown(Key.DOWN)) {
                _rotation = 135;
        }
        //
        // 保证瓢虫在视线内
        if (_y<0) {
                _y = 300;
        }
        if (_y>300) {
                _y = 0;
        }
        if (_x<0) {
                _x = 300;
        }
        if (_x>300) {
                _x = 0;
        }

}

怎么改只能在300*300的空间里边走  而不能从左边穿过到右边 我用的是FLASH8