chooseImage(e) {

    wx.chooseImage({

      sizeType: ['original', 'compressed'], //可选择原图或压缩后的图片

      sourceType: ['album', 'camera'], //可选择性开放访问相册、相机

      success: res => {

        const images = this.data.images.concat(res.tempFilePaths)

        // 限制最多只能留下3张照片

        this.data.images = images.length <= 3 ? images : images.slice(0, 3)

        this.setData(this.data)

        console.log(this.data)

      }

    })

  },

  removeImage(e) {

    const idx = e.target.dataset.idx

    this.data.images.splice(idx, 1)

    this.setData(this.data)

  },

  handleImagePreview(e) {

    const idx = e.target.dataset.idx

    const images = this.data.images

    wx.previewImage({

      current: images[idx], //当前预览的图片

      urls: images, //所有要预览的图片

    })

  },

  submitForm(e) {

    const title = this.data.title

    const content = this.data.content

    const imagess = this.data.images

    var that = this

    console.log(imagess);

    wx.uploadFile({

      url: 'http://127.0.0.1/upload.php',

      filePath: imagess[0],

      name: 'qimg',

      timeout: 10000,

      success: function(res){

        if(res.statusCode == 200){

          console.log(title)

          console.log(content)

          wx.request({

            url: 'http://127.0.0.1/tijiao.php',

            method: 'post',

            data: {

              x: res.data,

              y: title,

              z: content

            },

            header: {

              'content-type': 'application/x-www-form-urlencoded' // 默认值

            },

            success(res) {

              console.log(res)

            }

          })

        }

      }

    })

  },

<view class="container">

  <canvas canvas-id="firstCanvas" id='firstCanvas' bindtouchstart="bindtouchstart" bindtouchmove="bindtouchmove"></canvas>

  <view class="btn">

    <button type="warn" bindtap='clear'>

      清除

    </button>

    <button type="primary" bindtap='export'>

      提交

    </button>

  </view>

</view>

const app = getApp()

Page({

  data: {

    context: null,

    index: 0,

    height: 0,

    width: 0

  },

  /**记录开始点 */

  bindtouchstart: function (e) {

    this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y)

  },

  /**记录移动点，刷新绘制 */

  bindtouchmove: function (e) {

    this.data.context.lineTo(e.changedTouches[0].x, e.changedTouches[0].y);

    this.data.context.stroke();

    this.data.context.draw(true);

    this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y);

  },

  /**清空画布 */

  clear: function () {

    this.data.context.clearRect(0, 0, this.data.width, this.data.height);

    this.data.context.draw();

    this.data.context.setStrokeStyle('#00ff00')

    this.data.context.setLineWidth(2)

    this.data.context.setFontSize(20)

    let str = "签名区域";

    this.data.context.fillText(str, Math.ceil((this.data.width - this.data.context.measureText(str).width) / 2), Math.ceil(this.data.height / 2) - 20)

    this.data.context.draw()

  },

  /**导出图片 */

  export: function () {

    const that = this;

    this.data.context.draw(false, wx.canvasToTempFilePath({

      x: 0,

      y: 0,

      width: that.data.width,

      height: that.data.height,

      destWidth: that.data.width,

      destHeight: that.data.height,

      fileType: 'jpg',

      canvasId: 'firstCanvas',

      success(res) {

        wx.uploadFile({

          url: 'http://127.0.0.1/upload.php',

          filePath: res.tempFilePath,

          name: 'qimg',

          success(res) {

            console.log(res)

          },

          fail(err) {

            wx.showToast({

              title: '上传失败',

              icon: 'none',

              duration: 2000

            })

          }

        })

      },

      fail() {

        wx.showToast({

          title: '导出失败',

          icon: 'none',

          duration: 2000

        })

      }

    }))

  },

  onLoad: function (options) {

    console.log(options.id);

    if (options.id) {

      wx.showToast({

        title: '姓名' + options.id,

        icon: 'success',

        duration: 2000

      })

    }

  },

  onShow: function () {

    let query = wx.createSelectorQuery();

    const that = this;

    query.select('#firstCanvas').boundingClientRect();

    query.exec(function (rect) {

      let width = rect[0].width;

      let height = rect[0].height;

      that.setData({

        width,

        height

      });

      const context = wx.createCanvasContext('firstCanvas')

      that.setData({

        context: context

      })

      context.setStrokeStyle('#00ff00')

      context.setLineWidth(2)

      context.setFontSize(20)

      let str = "";

      context.fillText(str, Math.ceil((width - context.measureText(str).width) / 2), Math.ceil(height / 2) - 20)

      context.draw()

    });

  }

})