微信小程序实现拍照画布指定区域生成图片

/** * 生命周期函数--监听页面加载 */ onLoad: function(options) { requireJs.adaptionIphoneX(this);  this.ctx = wx.createCameraContext()  },

<camera wx:if='{{isShowCamera}}' device - position="width" flash="off" style="width:{{windowWidth}}px; height:{{windowHeight}}px;">  <cover-view class='camerabgImage-view'>  <cover-image class='bgImage' src='{{isIphoneX==true?"../../myImage/vehicle/biankuang_x.png":"../../myImage/vehicle/biankuang.png"}}'> </cover-image>   <cover-view class='cameratop-view1'>中华人民共和国机动车行驶证</cover-view>  <cover-view class='cameratop-view2'>（行驶证主页）</cover-view>  <cover-view class='cameracenter-view' style='top:{{isIphoneX==true?"52%":"62%"}}'>请对准左下角发证机关印章</cover-view>   <!-- 拍照按钮 -->   <cover-view class='camerabotton-view' style='bottom:{{isIphoneX==true?"75px":"0px"}}'>  <cover-image class='cancelphoto' src='../../myImage/vehicle/quxiao.png' bindtap='cancelPhotoAction'></cover-image>  <cover-image class='takephoto' src='../../myImage/vehicle/paizhao.png' bindtap='takePhotoAction'></cover-image>    <cover-view class='skipphoto' bindtap='skipphotoAction'>{{skipphotoStatus==1?"跳过":""}}  </cover-view>    </cover-view>  </cover-view>  </camera>  <canvas wx:if='{{isShowImage}}' canvas-id="image-canvas" style='width:{{windowWidth}}px; height:{{windowHeight}}px;'></canvas>

.camerabgImage-view{ height: 100%; width: 100%; position:absolute;}.bgImage{ width: 100%; height: 100%; position: absolute;} .cameratop-view1{ margin-top: 174rpx;}.cameratop-view2{ margin-top: 220rpx;}.cameratop-view1, .cameratop-view2{ width: 100%; display: flex; justify-content: center; position: absolute;  font-family: PingFangSC-Medium; font-size: 36rpx; color: #FFFFFF; letter-spacing: 0; text-align: center;} .cameracenter-view{ height: 44rpx; width: 100%; position: absolute;  font-family: PingFangSC-Medium; font-size: 32rpx; color: #FFFFFF; letter-spacing: 0; text-align: center;} /* 底部 */.camerabotton-view{ height: 200rpx; width: 100%; position:absolute;  display: flex; justify-content: space-around; align-items: center;}.cancelphoto{ width: 50rpx; height: 50rpx;}.takephoto{ width: 132rpx; height: 132rpx;}.skipphoto{ font-family: PingFangSC-Regular; font-size: 32rpx; color: #FFFFFF; letter-spacing: 0; text-align: center;}

onShow: function() { var that = this wx.authorize({  scope: 'scope.camera',  success: function (res) {  that.setData({   isShowCamera: true,  })  },  fail: function (res) {  console.log("" + res);  wx.showModal({   title: '请求授权您的摄像头',   content: '如需正常使用此小程序功能，请您按确定并在设置页面授权用户信息',   confirmText: '确定',   success: res => {   if (res.confirm) {    wx.openSetting({    success: function (res) {     console.log('成功');     console.log(res);     if (res.authSetting['scope.camera']) { //设置允许获取摄像头     console.log('设置允许获取摄像头')     wx.showToast({      title: '授权成功',      icon: 'success',      duration: 1000     })     that.setData({      isShowCamera: true,     })      } else { //不允许     wx.showToast({      title: '授权失败',      icon: 'none',      duration: 1000     })     wx.redirectTo({      url: 'addCarInfo/addCarInfo',     })     }    }    })   } else { //取消    wx.showToast({    title: '授权失败',    icon: 'none',    duration: 1000    })    wx.redirectTo({    url: 'addCarInfo/addCarInfo',    })   }   }  })   } }) },

/** * 页面的初始数据 */ data: { isShowCamera: false, width: 10, height: 10, src: "", image: "", skipphotoStatus: "0",// 1跳过 0没有跳过 isShowImage: false },

/** * 拍照 */ takePhotoAction: function() { var that = this that.ctx.takePhoto({  quality: 'high', //高质量  success: (res) => {  this.loadTempImagePath(res.tempImagePath);  }, }) },

 loadTempImagePath: function(options) { var that = this that.path = options wx.getSystemInfo({  success: function(res) {   // 矩形的位置  var image_x = 15;  var image_y = 150;  var image_width = that.data.width - 2 * 15;  var image_height = 238;   wx.getImageInfo({   src: that.path,   success: function(res) {   that.setData({    isShowImage: true,   })   that.canvas = wx.createCanvasContext("image-canvas", that)   //过渡页面中，图片的路径坐标和大小   that.canvas.drawImage(that.path, 0, 0, that.data.width, that.data.height)   wx.showLoading({    title: '数据处理中...',    icon: 'loading',    duration: 10000   })   // 这里有一些很神奇的操作,总结就是MD拍出来的照片规格居然不是统一的过渡页面中，对裁剪框的设定   that.canvas.setStrokeStyle('black')   that.canvas.strokeRect(image_x, image_y, image_width, image_height)   that.canvas.draw()   setTimeout(function() {    wx.canvasToTempFilePath({ //裁剪对参数    canvasId: "image-canvas",    x: image_x, //画布x轴起点    y: image_y, //画布y轴起点    width: image_width, //画布宽度    height: image_height, //画布高度    destWidth: image_width, //输出图片宽度    destHeight: image_height, //输出图片高度    success: function(res) {     that.setData({     image: res.tempFilePath,     })     //清除画布上在该矩形区域内的内容。     // that.canvas.clearRect(0, 0, that.data.width, that.data.height)     // that.canvas.drawImage(res.tempFilePath, image_x, image_y, image_width, image_height)     // that.canvas.draw()     wx.hideLoading()      console.log(res.tempFilePath);     //在此可进行网络请求     PublicJS.drivinglicenseUpload(res.tempFilePath, that.uploadFile);    },    fail: function(e) {     wx.hideLoading()     wx.showToast({     title: '出错啦...',     icon: 'loading'     })     if (this.data.skipphotoStatus == 1) {     wx.redirectTo({      url: 'addCarInfo/addCarInfo',     })     } else {     wx.navigateBack({      delta: 1     });     }    }    });   }, 1000);   }  })  } }) }, // 接口返回结果 uploadFile: function(data) {}