微信小程序保存二维码的过程

const ctx = wx.createCanvasContext('qrcodeCanvas');
ctx.drawImage('qrcodePath', 0, 0, canvasWidth, canvasHeight);
ctx.draw(false, () => {
  wx.canvasToTempFilePath({
    x: 0,
    y: 0,
    width: canvasWidth,
    height: canvasHeight,
    destWidth: canvasWidth,
    destHeight: canvasHeight,
    canvasId: 'qrcodeCanvas',
    success: (res) => {
      const tempFilePath = res.tempFilePath;
      // 接下来进行保存操作
    },
    fail: (err) => {
      console.error('canvasToTempFilePath failed', err);
    }
  });
});

wx.saveImageToPhotosAlbum({
  filePath: tempFilePath,
  success: (res) => {
    console.log('saveImageToPhotosAlbum success', res);
    wx.showToast({
      title: '保存成功',
      icon: 'success',
      duration: 2000
    });
  },
  fail: (err) => {
    console.error('saveImageToPhotosAlbum failed', err);
    wx.showToast({
      title: '保存失败',
      icon: 'none',
      duration: 2000
    });
  }
});

{
  "permission": {
    "scope.userLocation": {
      "desc": "保存图片到相册"
    }
  }
}