animation-放大缩小

onReady: function () {
      this.animation = wx.createAnimation({
        duration: 100,
        timingFunction: 'linear',
        delay: 10,
        transformOrigin: '50% 0 0'
      })    
    },
    onShow: function () {  
      let next = true;
      setInterval(function () {
        if (next) {
          this.animation.scale(0.9).step();
          next = !next;
        } else {
          this.animation.scale(1).step();
          next = !next;
        }
        this.setData({  //输出动画  
          animation: this.animation.export()
        })
      }.bind(this), 500)
    },