[]创建动画时画布的width和height与 实例化后的ani.size(width, height) 有什么区别

_proto_.onAnimation_BirdSing = function () {

        this.aniBirdSing = new Laya.Animation();

        this.aniBirdSing.loadAtlas("res/atlas/birdsing.json");

        this.aniBirdSing.interval = 35;			// 设置播放间隔（单位：毫秒）

		this.aniBirdSing.index = 0;             // 当前播放索引

        this.aniBirdSing.zOrder = 1;				

		this.aniBirdSing.play();

        

        this.aniBirdSing.pivot(0, 120);

        this.aniBirdSing.pos(94+0, 259+120);

        this.aniBirdSing.size(120, 120);

        console.log(this.aniBirdSing.width, this.aniBirdSing.height);        

        this.aniBirdSing.mouseEnable = true;

        Laya.stage.addChild(this.aniBirdSing);

        

    }