wxml:////////////// <canvas wx:if="{{d_c}}" style="z-index:20;border: 1px solid black;position:absolute;left:43rpx;top:80rpx;background-color:white;width:660rpx;height:{{c_height}}rpx;" canvas-id="myCanvas"/> <button wx:if="{{d_c}}" style='z-index:20;position:absolute;left:250rpx;top:{{c_height+100}}rpx;' bindtap='share'>分享到朋友圈</button> js:////////////// c_canvas:function(){     var that=this;     that.setData({d_c:true})     getApp().loading("请稍等……",30000)     wx.getImageInfo({       src: 'https://bmob-cdn-22087.bmobcloud.com/2018/11/28/98a3a696407c069080eabb219515a088.jpg',       success(res0){         wx.getImageInfo({           src: that.data.img,           success(res) {             console.log(res)             const cts = wx.createCanvasContext('myCanvas')             cts.setFillStyle('white');             cts.fillRect(0, 0, 200, 323.6);             //上面是画背景             cts.drawImage(res.path,6, 5, 350, res.height / res.width * 350)             //画图片             cts.drawImage(res0.path, 5, res.height / res.width * 350+15, 100, 100)             //画二维码             cts.setFillStyle('black')             cts.setFontSize(20);             cts.setTextAlign('left');             cts.fillText(that.data.title, 130, res.height / res.width * 350 + 50);             cts.fillText("--" + that.data.userNickName, 350 - that.data.userNickName.length * 15, res.height / res.width * 350 + 110);             //画标题和名字             that.setData({ c_height: (res.height / res.width * 350 + 130)*1.8})             cts.draw(false, function (e) {               wx.canvasToTempFilePath({                 canvasId: 'myCanvas',                 success: function (res) {                   // 获得图片临时路径                   that.data.canvasimg = res.tempFilePath;                 }               })             });             wx.hideToast()             console.log(res.height)           }         })       }     })   },   share:function(){     wx.saveImageToPhotosAlbum({       filePath: this.data.canvasimg,       success(res) {         console.log(res.errMsg)       },       fail(res) {         console.log(res.errMsg)       }     })   },