JSPDF内容如何居中显示

前端：ant design vue 1.6.2
JSPDF版本：2.3.0
需求：在搭配html2canvas截取页面div中内容作为图片，导出 PDF过程中，怎样让截取的图片能够在PDF页面居中显示？现在是顶在左上角

已解决

downloadPDF() {
      const downPdf = document.getElementById('KPImounth')
      html2canvas(downPdf).then((canvas) => {
        const image = canvas.toDataURL('image/jpeg', 1.0)
        const doc = new jsPDF('l', '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')
        doc.save('pdfname' + '.pdf')
      })
    },

是用 JsPDF 来生成pdf的吗
addImage 是可以指定位置的