html2canvas下载图片返回png文件与白色和右行只？

html2canvas(element, {
  backgroundColor: null
}).then(function(canvas) {
  // 下载透明背景的图片
  let url = canvas.toDataURL('image/png');
  let link = document.createElement('a');
  link.href = url;
  link.download = 'image.png';
  link.click();
});

html2canvas(element, {
  // 设置direction属性
  letterRendering: true,
  allowTaint: true,
  useCORS: true,
  scale: 2,
  logging: true,
  direction: 'ltr'
}).then(function(canvas) {
  // 下载图片
  let url = canvas.toDataURL('image/png');
  let link = document.createElement('a');
  link.href = url;
  link.download = 'image.png';
  link.click();
});