var qr = require('qr-image');
exports.createQRImage = function(res, str){
  var img = qr.image(str); // 将生成二维码图片
  res.writeHead(200, {'Content-Type': 'image/png'});
  img.pipe(res);
};

exports.genQrImage = function (text, url) {
  const tts = textToSVG.loadSync(path.join(__dirname, '../../msyh.ttf'));
  const tSvg = tts.getSVG(text, {
    x: 0,
    y: 0,
    fontSize: 20,
    anchor: 'top'
  });
  const margin = 35; // 二维码的左右边距
  const top = 90; // 二维码距顶部的距离
  var sourceImage = images(path.join(__dirname, '../../source.png'));
  var w = sourceImage.width(); // 模板图片的宽度
  return svg2png(tSvg)
    .then((rst) => {
      var textImage = images(rst);
      var qrImage = images(qr.imageSync(url, {type: 'png'})).size(w - margin * 2); // 二维码的尺寸为：模板图片的宽度减去左右边距
      return sourceImage
        .draw(qrImage, margin, top) // 二维码的位置：x=左边距，y=top
        .draw(textImage, (w - textImage.width()) / 2, top + qrImage.height() + 10) // 底部文字，x为居中显示，y=top+二维码的高度+10
        .encode('png', {quality: 90});
    })
    .catch(e => console.error(e));
};

myShareQrImage: function* (next) {
  var _text = "联系人：xxx   手机号：13200000000";
  var _url = "http://www.cnblogs.com/jaxu";
  var _buffer = yield BizUtils.genQrImage(_text, _url);
  this.res.setHeader('Content-type', 'image/png');
  this.body = _buffer;
  yield next;
}