javascript - 如何使用jsPDF使图像适合页面中心？

这个问题需要一些老式的CSS技巧。我回想起我们过去如何将图像居中position: absolute;，然后计算图像宽度和画布宽度，取反然后将其除以一半。在这里使用相同的技术就像一个魅力！

const marginX = (pageWidth - canvasWidth) / 2;
const marginY = (pageHeight - canvasHeight) / 2;

因此，完整的功能如下所示：

const printAsPdf = () => {
  html2canvas(pageElement.current, {
    useCORS: true,
    allowTaint: true,
    scrollY: -window.scrollY,
  }).then(canvas => {
    const image = canvas.toDataURL('image/jpeg', 1.0);
    const doc = new jsPDF('p', 'px', 'a4');
    const pageWidth = doc.internal.pageSize.getWidth();
    const pageHeight = doc.internal.pageSize.getHeight();

    const widthRatio = pageWidth / canvas.width;
    const heightRatio = pageHeight / canvas.height;
    const ratio = widthRatio > heightRatio ? heightRatio : widthRatio;

    const canvasWidth = canvas.width * ratio;
    const canvasHeight = canvas.height * ratio;

    const marginX = (pageWidth - canvasWidth) / 2;
    const marginY = (pageHeight - canvasHeight) / 2;

    doc.addImage(image, 'JPEG', marginX, marginY, canvasWidth, canvasHeight);
    doc.output('dataurlnewwindow');
  });
};