// 页面导出为pdf格式
import html2Canvas from 'html2canvas'
import JsPDF from 'jspdf'

const htmlToPdf = {
  getPdf(title: string, id: string) {
    html2Canvas(document.querySelector(id)!, {
      allowTaint: false,
      taintTest: false,
      logging: false,
      useCORS: true,
      dpi: window.devicePixelRatio * 4, // 将分辨率提高到特定的DPI 提高四倍
      scale: 4, // 按比例增加分辨率
    }).then((canvas) => {
      var pdf = new JsPDF('p', 'mm', 'a4') // A4纸，纵向
      var ctx = canvas.getContext('2d')
      var a4w = 190
      var a4h = 272 // A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277
      var imgHeight = Math.floor((a4h * canvas.width) / a4w) // 按A4显示比例换算一页图像的像素高度
      var renderedHeight = 0

      while (renderedHeight < canvas.height) {
        var page = document.createElement('canvas')
        page.width = canvas.width
        page.height = Math.min(imgHeight, canvas.height - renderedHeight) // 可能内容不足一页

        // 用getImageData剪裁指定区域，并画到前面创建的canvas对象中
        page.getContext('2d')!.putImageData(
          ctx!.getImageData(
            0,
            renderedHeight,
            canvas.width,
            Math.min(imgHeight, canvas.height - renderedHeight),
          ),
          0,
          0,
        )
        pdf.addImage(
          page.toDataURL('image/jpeg', 1.0),
          'JPEG',
          10,
          10,
          a4w,
          Math.min(a4h, (a4w * page.height) / page.width),
        ) // 添加图像到页面，保留10mm边距

        renderedHeight += imgHeight
        if (renderedHeight < canvas.height) {
          pdf.addPage() // 如果后面还有内容，添加一个空页
        }
        // delete page;
      }
      pdf.save(`${title}.pdf`)
    })
  },
}

export default htmlToPdf