微信小程序分享时，封面图片裁剪为5:4
直接贴代码：
//裁剪分享的图片为5:4//传入图片地址 cutShareImg:function(imgurl){ let that=this; wx.getImageInfo({ src: imgurl, // 这里填写网络图片路径 success: (res) = { let ctx = wx.createCanvasContext('canvas'); let canvasW = 640, canvasH = res.height; if (res.width / res.height 5 / 4) { // 长宽比大于5:4 canvasW = res.height * 5 / 4; } ctx.drawImage(res.path, (res.width - canvasW) / 2, 0, canvasW, canvasH, 0, 0, canvasW, canvasH) ctx.draw(false, () = { wx.canvasToTempFilePath({ width: canvasW, height: canvasH, destWidth: canvasW, destHeight: canvasH, canvasId: 'canvas', fileType: 'jpg', success: (res) = { //设置分享图片路径 that.setData({ shareimg:res.tempFilePath }); } }) }) } }); },html代码
!-- 裁剪分享时图片的canvas --canvas style="position: absolute; top: -1000px; left: -1000px; width: 640px; height: 640px; background: #000;" canvas-id="canvas"/canvas分享的时候
onShareAppMessage: function () {return {title: title,desc: '',path: '',imageUrl: this.data.shareimg,}}当然还需要配置小程序downloadFile合法域名，及图片路径的域名
