视差怎么判断边界啊,网上米找到js的,求助大神

Cocos2d-x JavaScript
#1 
var HelloWorldLayer = cc.Layer.extend({
    _bg1: null,
    _bg2: null,
    _bg3: null,
    _bg: null,
    _size: null,
    ctor: function () {

        this._super();
        this._size = cc.winSize;

        this._bg = new cc.ParallaxNode();

        this._bg1 = new cc.Sprite(res.bg1_png);

        this._bg2 = new cc.Sprite(res.bg2_png);
      
        this._bg.addChild(this._bg1, 3, cc.p(0.5, 0), cc.p(this._bg1.width / 2, this._bg1.height / 2));
        this._bg.addChild(this._bg2, 2, cc.p(1.3, 0), cc.p(this._bg2.width / 2, this._bg2.height / 2));

        this.addChild(this._bg);


        //滑动侦听
        var listener = cc.EventListener.create({
            event: cc.EventListener.TOUCH_ONE_BY_ONE,
            swallowTouches: true,
            onTouchBegan: function (touch, event) {
                return true;
            },
            onTouchMoved: function (touch, event) {
                var target = event.getCurrentTarget();
                var delta = touch.getDelta();
                // 移动当前按钮精灵的坐标位置

这里我想判断视觉移动不要让图片超出屏幕边界怎么判断啊,想到我头大了,求高人指点

                this._bg.setPositionX(this._bg.getPositionX()+delta.x);

            }.bind(this),
            onTouchEnded: function (touch, event) {            // 点击事件结束处理
            }.bind(this)
        });

        // 注册监听器
        cc.eventManager.addListener(listener, this._bg);

        return true;
    }
});

var HelloWorldScene = cc.Scene.extend({
    onEnter: function () {
        this._super();
        var layer = new HelloWorldLayer();
        this.addChild(layer);
    }
});




```

跪求高人指点,我是小白,初学的
#2

哎,算了,我解决了,结贴了:2: