Page({
  data: {
    touch: {
      distance: 0,
      scale: 1,
      baseWidth: null,
      baseHeight: null,
      scaleWidth: null,
      scaleHeight: null
    }
  },
  touchStartHandle(e) {
    // 单手指缩放开始，也不做任何处理 
    if (e.touches.length == 1) {
      console.log("单滑了")
      return
    }
    console.log(\'双手指触发开始\')
    // 注意touchstartCallback 真正代码的开始 
    // 一开始我并没有这个回调函数，会出现缩小的时候有瞬间被放大过程的bug 
    // 当两根手指放上去的时候，就将distance 初始化。 
    let xMove = e.touches[1].clientX - e.touches[0].clientX;
    let yMove = e.touches[1].clientY - e.touches[0].clientY;
    let distance = Math.sqrt(xMove * xMove + yMove * yMove);
    this.setData({
      \'touch.distance\': distance,
    })
  },
  touchMoveHandle(e) {
    let touch = this.data.touch
    // 单手指缩放我们不做任何操作 
    if (e.touches.length == 1) {
      console.log("单滑了");
      return
    }
    console.log(\'双手指运动开始\')
    let xMove = e.touches[1].clientX - e.touches[0].clientX;
    let yMove = e.touches[1].clientY - e.touches[0].clientY;
    // 新的 ditance 
    let distance = Math.sqrt(xMove * xMove + yMove * yMove);
    let distanceDiff = distance - touch.distance;
    let newScale = touch.scale + 0.005 * distanceDiff
    // 为了防止缩放得太大，所以scale需要限制，同理最小值也是 
    if (newScale >= 2) {
      newScale = 2
    }
    if (newScale <= 0.6) {
      newScale = 0.6
    }
    let scaleWidth = newScale * touch.baseWidth
    let scaleHeight = newScale * touch.baseHeight
    // 赋值 新的 => 旧的 
    this.setData({
      \'touch.distance\': distance,
      \'touch.scale\': newScale,
      \'touch.scaleWidth\': scaleWidth,
      \'touch.scaleHeight\': scaleHeight,
      \'touch.diff\': distanceDiff
    })
  },
  load: function (e) {
    // bindload 这个api是<image>组件的api类似<img>的onload属性 
    this.setData({
      \'touch.baseWidth\': e.detail.width,
      \'touch.baseHeight\': e.detail.height,
      \'touch.scaleWidth\': e.detail.width,
      \'touch.scaleHeight\': e.detail.height
    });
  }
})

<image mode=\'scaleToFill\' src=\'../../../images/01.jpg\' bindtouchstart=\'touchStartHandle\' bindtouchmove=\'touchMoveHandle\' bindload=\'load\' style="width: {{ touch.scaleWidth }}px;height: {{ touch.scaleHeight }}px"></image>