屏幕抖动

var app = new PIXI.Application(500,800);
document.body.appendChild(app.view);
var bg = new PIXI.Sprite.fromImage("res/lianxi/findFace/bg.png");
app.stage.addChild(bg);
//文本样式
var style = {
    font : '20px 微软雅黑',
    fill : '#F7EDCA',
    stroke : '#4a1850',
    strokeThickness : 3,
    dropShadow : true,
    dropShadowColor : '#000000',
    dropShadowAngle : Math.PI / 6,
    dropShadowDistance : 2
};
//创建文本
var timeTxt = new PIXI.Text("点击头像抖屏",style);
app.stage.addChild(timeTxt);
timeTxt.x = 180;
timeTxt.y = 30;
//头像
var headPic = new PIXI.Sprite.fromImage("res/lianxi/findFace/1.png");
headPic.x = 250;
headPic.y = 350;
headPic.anchor.set(0.5, 0.5);
app.stage.addChild(headPic);