问题以及解决：

吐槽遇到的问题~

在写微信小程序的时候，采用wx.canvasToTempFilePath压缩图片且上传的时候，安卓一切正常，我在开发工具上也一切正常，偏偏ios上就不正常，不正常不是指压缩失败，而是明明也压缩成功了，竟然发不起网络请求，离大谱。因为所有请求的入参都会经过sm2加密，ios压缩成功后想要发起请求，就卡在了加密这步，无法执行下面的请求方法，打印出来加密前的参数也都没问题，但就是卡住了不往下走了，导致压根没发起请求，玄学。更玄的是去年ios都没问题，代码也没动过，现在ios就不行了。经过排查，wx.canvasToTempFilePath加上了两个属性destWidth和destHeight定义又都成功了，奇怪明明是非必填属性，安卓我也没填采用默认的都没问题，说到底我也不确定是不是这个问题，因为也改了其它逻辑，不过现在确实是一切正常了。ios奇奇怪的问题真是太多了，晕。

如今的压缩代码如下（当宽度大于高度时图片可向左旋转）：

wx.createCanvasContext(‘attendCanvasId’)一直提示已废弃，不过以前用了我就不改了，而且改新的也麻烦hhh，主要是也能用：

  picCompress(img, width = 600, size = 102, moreCallback) {let that = thislet imgSize = img.tempFiles[0].size / 1024console.log('img', img)let path = img.tempFiles[0].pathconsole.log('图片大小(kb)', imgSize);return new Promise((resolve, reject) => {wx.getImageInfo({src: img.tempFilePaths[0],success: function (imgInfo) {console.log('获取图片信息', imgInfo)let ctx = wx.createCanvasContext('attendCanvasId');/*** 压缩图片：* 图片宽度大于 width 的时候压缩，小于的时候不操作*/if (imgInfo.width > width) {var canvasWidth = width;var canvasHeight = (width * imgInfo.height) / imgInfo.width;//设置canvas尺寸that.setData({canvasWidth: canvasWidth,canvasHeight: canvasHeight});//将图片填充在canvas上if (canvasWidth < canvasHeight) {//顺时针旋转270度that.setData({canvasWidth: (width * imgInfo.height) / imgInfo.width,canvasHeight: width,})console.log('宽高：',canvasWidth,canvasHeight)ctx.translate(((width * imgInfo.height) / imgInfo.width) / 2, width / 2)ctx.rotate(270 * Math.PI / 180)ctx.drawImage(path, -width / 2, -((width * imgInfo.height) / imgInfo.width) / 2, width, (width * imgInfo.height) / imgInfo.width);}else {ctx.drawImage(path, 0, 0, canvasWidth, canvasHeight);}// ctx.drawImage(path, 0, 0, canvasWidth, canvasHeight);ctx.draw(false, () => {//下载canvas图片//保存临时文件setTimeout(() => {wx.canvasToTempFilePath({ canvasId: 'attendCanvasId',fileType: 'jpg',quality: 0.5,/*   width: 0,height: 0,   */destWidth: that.data.canvasWidth, destHeight: that.data.canvasHeight,               success: function (res) {console.log(res.tempFilePath)wx.getImageInfo({src: res.tempFilePath,success: function (res) {console.log('---------------1')console.log('压缩成功')console.log(res)let sourcePhoto = wx.getFileSystemManager().readFileSync(res.path, 'base64')console.log('------------url:',res.path) let t = {tempFilePaths:res.path, picBase64:sourcePhoto}resolve(t)}});},fail: function (error) {console.log(error)}})}, 500)})} else if (imgSize > size) { // 宽度小于width 但是大小大于size 不压尺寸压质量var canvasWidth = imgInfo.width;var canvasHeight = imgInfo.height;//设置canvas尺寸that.setData({canvasWidth: canvasWidth,canvasHeight: canvasHeight});//将图片填充在canvas上if (canvasWidth < canvasHeight) {//顺时针旋转270度that.setData({canvasWidth: (width * imgInfo.height) / imgInfo.width,canvasHeight: width,})ctx.translate(((width * imgInfo.height) / imgInfo.width) / 2, width / 2)ctx.rotate(270 * Math.PI / 180)ctx.drawImage(path, -width / 2, -((width * imgInfo.height) / imgInfo.width) / 2, width, (width * imgInfo.height) / imgInfo.width);}else {ctx.drawImage(path, 0, 0, canvasWidth, canvasHeight);}ctx.draw(false, () => {setTimeout(() => {wx.canvasToTempFilePath({ canvasId: 'attendCanvasId',fileType: 'jpg',quality: 0.5,/*   width: 0,height: 0,   */destWidth: that.data.canvasWidth, destHeight: that.data.canvasHeight, success: function (res) {console.log(res.tempFilePath)wx.getImageInfo({src: res.tempFilePath,success: function (res) {console.log('---------------2')console.log('压缩成功')console.log(res)let sourcePhoto = wx.getFileSystemManager().readFileSync(res.path, 'base64')console.log('------------url:',res.path) // moreCallback(res.path, sourcePhoto) tempFilePaths, picBase64let t = {tempFilePaths:res.path, picBase64:sourcePhoto}resolve(t)}});},fail: function (error) {console.log(error)}})}, 500)//下载canvas图片});} else {let canvasWidth = imgInfo.widthlet canvasHeight = imgInfo.heightconsole.log('宽高：',canvasWidth,canvasHeight)//将图片填充在canvas上if (canvasWidth < canvasHeight) {//顺时针旋转270度that.setData({canvasWidth: (width * imgInfo.height) / imgInfo.width,canvasHeight: width,})ctx.translate(((width * imgInfo.height) / imgInfo.width) / 2, width / 2)ctx.rotate(270 * Math.PI / 180)ctx.drawImage(path, -width / 2, -((width * imgInfo.height) / imgInfo.width) / 2, width, (width * imgInfo.height) / imgInfo.width);}else {ctx.drawImage(path, 0, 0, canvasWidth, canvasHeight);}ctx.draw(false, () => {setTimeout(() => {wx.canvasToTempFilePath({ canvasId: 'attendCanvasId',fileType: 'jpg',quality: 0.5,/*   width: 0,height: 0,   */destWidth: that.data.canvasWidth, destHeight: that.data.canvasHeight, success: function (res) {console.log(res.tempFilePath)wx.getImageInfo({src: res.tempFilePath,success: function (res) {console.log('---------------3')console.log('压缩成功')console.log(res)let sourcePhoto = wx.getFileSystemManager().readFileSync(res.path, 'base64')console.log('------------url:',res.path) // moreCallback(res.path, sourcePhoto) tempFilePaths, picBase64let t = {tempFilePaths:res.path, picBase64:sourcePhoto}resolve(t)}});},fail: function (error) {console.log(error)}})}, 500)});}},fail: function (getInfoErr) {that.data.loading.clear()console.log(getInfoErr)// wx.hideLoading();wx.showToast({title: '获取图片信息失败',icon: 'error',duration: 2000});}})})},

压缩成功后，直接把图片转换成base64，然后直接返回一个promise结果出去，再进行操作后发起请求。

         let t = _this.picCompress(res, 600, 100)  .then(res => {// 请求})

886~

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