解决jsPDF导出html,黑屏，白屏，不全问题

1.项目中用到导出pdf，用到jsPDF,canvas,
2.网上很多方法，存在黑屏白屏，只能解决当前可视区域的问题
3.其中参考 https://blog.csdn.net/qq_36706878/article/details/111289963和https://blog.csdn.net/m0_37879526/article/details/103827235?utm_medium=distribute.pc_relevant_bbs_down.none-task--2~all~first_rank_v2~rank_v29-5.nonecase&depth_1-utm_source=distribute.pc_relevant_bbs_down.none-task--2~all~first_rank_v2~rank_v29-5.nonecase ，这两位博友的博客，
使用方法：引入

方法名

downloadC() {//方法名绑定你的导出按钮

var _this = this;

var targetDom = $("#export_content");//你的目标元素id

var copyDom = targetDom.clone();

copyDom.width(targetDom.width() + "px");

copyDom.height(targetDom.height() + "px");

$(\'body\').append(copyDom);

console.log(\'copyDom\',copyDom)

html2canvas(copyDom, {

onrendered:function(canvas) {

var contentWidth = canvas.width;

var contentHeight = canvas.height;

var pageHeight = contentWidth / 592.28 * 841.89;

var leftHeight = contentHeight;

var position = 0;

var f="p";

// var imgWidth = 595.28;

// var imgHeight = 592.28/contentWidth * contentHeight;

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 { // 分页

while(leftHeight > 0) {

pdf.addImage(pageData, \'JPEG\', 0, position, imgWidth, imgHeight)

leftHeight -= pageHeight;

position -= 841.89;

// position += 841.89;

//避免添加空白页

if(leftHeight > 0) {

pdf.addPage();

}

// contentHeight > contentWidth ? f = \'p\' : f = \'l\';

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

// _this.aaa = canvas.toDataURL();

// var pdf = new jsPDF(f, \'px\', [imgWidth, imgHeight]);

// pdf.addImage(pageData, \'png\', 0, 0, imgWidth, imgHeight);

pdf.save(\'content.pdf\');

copyDom.remove();

}

});