2022微信小程序通过保存图片分享到朋友圈的功能实现

wx.getImageInfo({            
  src:'https://xxx.jpg',//服务器返回的带参数的小程序码地址
  success: function (res) {
    //res.path是网络图片的本地地址
    qrCodePath = res.path;
  },
  fail: function (res) {
    //失败回调
  }
});

canvasCtx.draw(false,function(res){
});

/**
 * 绘制分享的图片
 * @param goodsPicPath 商品图片的本地链接
 * @param qrCodePath 二维码的本地链接
 */
drawSharePic: function (goodsPicPath, qrCodePath) {
  wx.showLoading({
    title: '正在生成图片...',
    mask: true,
  });
  //y方向的偏移量，因为是从上往下绘制的，所以y一直向下偏移，不断增大。
  let yOffset = 20;
  const goodsTitle = this.data.orderDetail.paltProduct.name1;
  let goodsTitleArray = [];
  //为了防止标题过长，分割字符串,每行18个
  for (let i = 0; i < goodsTitle.length / 18; i++) {
    if (i > 2) {
      break;
    }
    goodsTitleArray.push(goodsTitle.substr(i * 18, 18));
  }
  const price = this.data.orderDetail.price;
  const marketPrice = this.data.orderDetail.marketPrice;
  const title1 = '您的好友邀请您一起分享精品好货';
  const title2 = '立即打开看看吧';
  const codeText = '长按识别小程序码查看详情';
  const imgWidth = 780;
  const imgHeight = 1600;

  const canvasCtx = wx.createCanvasContext('shareCanvas');
  //绘制背景
  canvasCtx.setFillStyle('white');
  canvasCtx.fillRect(0, 0, 390, 800);
  //绘制分享的标题文字
  canvasCtx.setFontSize(24);
  canvasCtx.setFillStyle('#333333');
  canvasCtx.setTextAlign('center');
  canvasCtx.fillText(title1, 195, 40);
  //绘制分享的第二行标题文字
  canvasCtx.fillText(title2, 195, 70);
  //绘制商品图片
  canvasCtx.drawImage(goodPicPath, 0, 90, 390, 390);
  //绘制商品标题
  yOffset = 490;
  goodsTitleArray.forEach(function (value) {
    canvasCtx.setFontSize(20);
    canvasCtx.setFillStyle('#333333');
    canvasCtx.setTextAlign('left');
    canvasCtx.fillText(value, 20, yOffset);
    yOffset += 25;
  });
  //绘制价格
  yOffset += 8;
  canvasCtx.setFontSize(20);
  canvasCtx.setFillStyle('#f9555c');
  canvasCtx.setTextAlign('left');
  canvasCtx.fillText('￥', 20, yOffset);
  canvasCtx.setFontSize(30);
  canvasCtx.setFillStyle('#f9555c');
  canvasCtx.setTextAlign('left');
  canvasCtx.fillText(price, 40, yOffset);
  //绘制原价
  const xOffset = (price.length / 2 + 1) * 24 + 50;
  canvasCtx.setFontSize(20);
  canvasCtx.setFillStyle('#999999');
  canvasCtx.setTextAlign('left');
  canvasCtx.fillText('原价:¥' + marketPrice, xOffset, yOffset);
  //绘制原价的删除线
  canvasCtx.setLineWidth(1);
  canvasCtx.moveTo(xOffset, yOffset - 6);
  canvasCtx.lineTo(xOffset + (3 + marketPrice.toString().length / 2) * 20, yOffset - 6);
  canvasCtx.setStrokeStyle('#999999');
  canvasCtx.stroke();
  //绘制最底部文字
  canvasCtx.setFontSize(18);
  canvasCtx.setFillStyle('#333333');
  canvasCtx.setTextAlign('center');
  canvasCtx.fillText(codeText, 195, 780);
  //绘制二维码
  canvasCtx.drawImage(qrCodePath, 95, 550, 200, 200);
  canvasCtx.draw();
  //绘制之后加一个延时去生成图片，如果直接生成可能没有绘制完成，导出图片会有问题。
  setTimeout(function () {
    wx.canvasToTempFilePath({
      x: 0,
      y: 0,
      width: 390,
      height: 800,
      destWidth: 390,
      destHeight: 800,
      canvasId: 'shareCanvas',
      success: function (res) {
        that.setData({
          shareImage: res.tempFilePath,
          showSharePic: true
        })
        wx.hideLoading();
      },
      fail: function (res) {
        console.log(res)
        wx.hideLoading();
      }
    })
  }, 2000);
},