// 页面导出为pdf格式 //title表示为下载的标题，html表示document.querySelector('#myPrintHtml')
import html2Canvas from 'html2canvas'
import JsPDF from 'jspdf'

const htmlPdf = {
  getPdf(title, html) {
    html2Canvas(html, {
      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) => {
      const pdf = new JsPDF('p', 'mm', 'a4') // A4纸，纵向
      const ctx = canvas.getContext('2d')
      const a4w = 190
      const a4h = 200 // A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277
      const imgHeight = Math.floor((a4h * canvas.width) / a4w) // 按A4显示比例换算一页图像的像素高度
      let renderedHeight = 0
      while (renderedHeight < canvas.height) {
        const page = document.createElement('canvas')
        page.width = canvas.width
        page.height = Math.min(imgHeight, canvas.height - renderedHeight)

        // 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;
      }
      // 保存文件
      pdf.save(`${ title }.pdf`)
    })
  },
}

export default htmlPdf

