微信小程序单指拖拽和双指缩放旋转

<view style="height: 100vh; width: 100vw">
  <image
    src="..."
    style="transform: translate({{translateX}}px, {{translateY}}px) scale({{scale}}) rotate({{rotate}}deg);"
    catch:touchstart="touchStart"
    catch:touchmove="touchMove"
    catch:touchend="touchEnd"
  />
</view>

Page({
  data: {
    translateX: 0, // 位移x坐标 单位px
    translateY: 0, // 位移y坐标 单位px
    distance: 0, // 双指接触点距离
    scale: 1, // 缩放倍数
    rotate: 0, // 旋转角度
    oldRotate: 0, // 上一次旋转停止后的角度
    startMove: { // 起始位移距离
      x: 0,
      y: 0,
    },
    startTouches: [] // 起始点touch数组
  },
})

touchStart(e) {
  const touches = e.touches
  const { translateX, translateY } = this.data
  const { pageX, pageY } = touches[0]
  this.data.startMove = {
    x: pageX - translateX,
    y: pageY - translateY
  }
  this.data.startTouches = touches
},

touchMove(e) {
  const touches = e.touches
  const { pageX: onePageX, pageY: onePageY } = touches[0]
  const { startMove } = this.data
  this.setData({
    translateX: onePageX - startMove.x,
    translateY: onePageY - startMove.y
  })
}

touchMove(e) {
  const touches = e.touches
  const { pageX: onePageX, pageY: onePageY } = touches[0]
  const { startMove, scale, distance: oldDistance, startTouches } = this.data
  if (touches.length === 2 && startTouches.length === 2) {
      // 双指缩放
    const { pageX: twoPageX, pageY: twoPageY } = touches[1]
    // 求出当前双指距离
    const distance = Math.sqrt((twoPageX - onePageX) ** 2 + (twoPageY - onePageY) ** 2)
    this.data.distance = distance
    this.setData({
      scale: scale * (distance / (oldDistance || distance))
    })
  } else if (startTouches.length !== 2) {
      // 单指拖拽
    this.setData({
      translateX: onePageX - startMove.x,
      translateY: onePageY - startMove.y
    })
  }
}

touchMove(e) {
  const touches = e.touches
  const { pageX: onePageX, pageY: onePageY } = touches[0]
  const { startMove, scale, distance: oldDistance, startTouches, oldRotate } = this.data
  if (touches.length === 2 && startTouches.length === 2) {
    const { pageX: twoPageX, pageY: twoPageY } = touches[1]
    const distance = Math.sqrt((twoPageX - onePageX) ** 2 + (twoPageY - onePageY) ** 2)
+   let rotate = this.getAngle(touches[0], touches[1]) - this.getAngle(startTouches[0], startTouches[1]) + oldRotate
    // 如果大于360度，就减去360
+   rotate = rotate > 360 ? rotate - 360 : rotate
    this.data.distance = distance
    this.setData({
      scale: scale * (distance / (oldDistance || distance)),
+     rotate
    })
  } else if (startTouches.length !== 2) {
    this.setData({
      translateX: onePageX - startMove.x,
      translateY: onePageY - startMove.y
    })
  }
},

//getAngle
getAngle(p1, p2) {
  const x = p1.pageX - p2.pageX
  const y = p1.pageY- p2.pageY
  return Math.atan2(y, x) * 180 / Math.PI
}

touchEnd() {
  // 保存当前旋转角度
  this.data.oldRotate = this.data.rotate
},