//页面显示<canvas id="myCanvas" type="2d" style=" width: 700rpx; height: 600rpx;" />onShareShow(e){var that = this;let user_id = wx.getStorageSync('user_id');let sharePicUrl = wx.getStorageSync('sharePicUrl');if(app.isBlank(user_id) || app.isBlank(that.data.ids)){wx.showToast({title: '先完善学员信息~', //提示的内容duration: 2000, //持续的时间icon: 'error', //图标有success、error、loading、none四种mask: true //显示透明蒙层 防止触摸穿透})return false;}// if(!sharePicUrl){that.createPoster();return false;// }that.showModal();},//生成动态海报createPoster() {wx.showToast({title: '图片生成中',mask: true,icon: 'loading',duration: 100000})var that =this;console.log(that.data);let w = 0wx.getSystemInfo({success: function (res) {w = res.screenWidth}})console.log(w);// return falsewx.createSelectorQuery().select('#myCanvas') // 在 WXML 中填入的 id.fields({ node: true, size: true }).exec((res) => {// Canvas 对象const canvas = res[0].node// 渲染上下文const ctx = canvas.getContext('2d')// Canvas 画布的实际绘制宽高const width = res[0].widthconst height = res[0].heightconst rpx =width/750// 初始化画布大小const dpr = wx.getWindowInfo().pixelRatiocanvas.width = width * dprcanvas.height = height * dprctx.scale(dpr, dpr)// 图片对象const image = canvas.createImage()//本地背景图 const imgs = canvas.createImage() //用户头像const qrcodes = canvas.createImage()//接口返回二维码图片// 图片加载完成回调image.onload = () => {// 将图片绘制到 canvas 上ctx.drawImage(image, 0, 0,width,height)ctx.drawImage(imgs,rpx*140,rpx*260,rpx*170,rpx*200)ctx.drawImage(qrcodes,rpx*140,rpx*520,rpx*60,rpx*60)// 文本 一定要写到图片后面 要不然会被盖住ctx.font = "12px SimHei";ctx.textAlgin = "left"ctx.fillStyle = "#333333";ctx.fillText(that.data.userClassInfo.user_name.substr(0,8), rpx*340, rpx*330);ctx.fillText(that.data.userClassInfo.userSubject.substr(0,8), rpx*340, rpx*410);ctx.fillText(that.data.userClassInfo.className.substr(0,10), rpx*340, rpx*480);}console.log(that.data);// 设置图片srcimage.src = that.data.shareImgimgs.src = that.data.userImgUrlqrcodes.src = that.data.qrcode//没加定时器之前合成的图片是一片灰色，加了之后才有图片，测试了一下最少需要400毫秒setTimeout(()=>{wx.canvasToTempFilePath({canvas: canvas,success: res => {wx.hideToast();// 生成的图片临时文件路径this.setData({sharePicUrl:res.tempFilePath}) wx.setStorageSync('sharePicUrl', res.tempFilePath);that.showModal();},})},1000)})},效果如下：
小程序二维码 头像 班级信息 都是动态生成。
