echart图导出PDF

echart图导出PDF

 //downloadPdf(fileName, className) fileName:导出文件名称 ， className:需要导出的div对应的class

function downloadPdf(fileName, className) {
  var downIndex = layer.load();
  var target = document.getElementsByClassName(className)[0];
  target.style.background = "#FFFFFF";

  html2canvas(target).then(canvas => {
    var contentWidth = canvas.width;
    var contentHeight = canvas.height;

    //一页pdf显示html页面生成的canvas高度;
    var pageHeight = contentWidth / 592.28 * 841.89;
    //未生成pdf的html页面高度
    var leftHeight = contentHeight;
    //页面偏移
    var position = 0;
    //a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
    var imgWidth = 595.28;
    var imgHeight = 592.28/contentWidth * contentHeight;

    var pageData = canvas.toDataURL('image/jpeg', 1.0);

    var pdf = new jsPDF('', 'pt', 'a4');

    //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
    //当内容未超过pdf一页显示的范围，无需分页
    if (leftHeight < pageHeight) {
      pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight );
    } else {
      while(leftHeight > 0) {
        pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
        leftHeight -= pageHeight;
        position -= 841.89;
        //避免添加空白页
        if(leftHeight > 0) {
          pdf.addPage();
        }
      }
    }

    pdf.save(fileName+".pdf");
    layer.close(downIndex);
  })
}