使用JavaScript从PDF文件中提取图像 [英] Extract images from PDF file with JavaScript

问题描述

我想编写JavaScript代码来从PDF文件中提取所有图像文件，或者将它们作为JPG或其他图像格式获取。已经有一些JavaScript代码用于读取PDF文件，例如在PDF查看器中 pdf-js 。

I want to write JavaScript code to extract all image files from a PDF file, perhaps getting them as JPG or some other image format. There is already some JavaScript code for reading a PDF file, for example in the PDF viewer pdf-js.

window.addEventListener('change', function webViewerChange(evt) {
  var files = evt.target.files;
  if (!files || files.length === 0)
    return;

  // Read the local file into a Uint8Array.
  var fileReader = new FileReader();
  fileReader.onload = function webViewerChangeFileReaderOnload(evt) {
    var buffer = evt.target.result;
    var uint8Array = new Uint8Array(buffer);
    PDFView.open(uint8Array, 0);
  };

  var file = files[0];
  fileReader.readAsArrayBuffer(file);
  PDFView.setTitleUsingUrl(file.name);
  ........

我可以使用此代码来帮助读取和提取图像文件吗？

Can I use this code to help read and extract the image files?

推荐答案

如果您打开一个页面同 pdf.js ，例如

If you open a page with pdf.js, for example

PDFJS.getDocument({url: <pdf file>}).then(function (doc) {
    doc.getPage(1).then(function (page) {
        window.page = page;
    })
})

然后你可以使用 getOperatorList 搜索 paintJpegXObject 对象并获取资源。

you can then use getOperatorList to search for paintJpegXObject objects and grab the resources.

window.objs = []
page.getOperatorList().then(function (ops) {
    for (var i=0; i < ops.fnArray.length; i++) {
        if (ops.fnArray[i] == PDFJS.OPS.paintJpegXObject) {
            window.objs.push(ops.argsArray[i][0])
        }
    }
})

现在 args 将包含您需要获取的该页面的资源列表。

Now args will have a list of the resources from that page that you need to fetch.

console.log(window.args.map(function (a) { page.objs.get(a) }))

应打印在控制台上有一堆< img /> 对象，其中包含data-uri src = 属性。这些可以直接插入页面，或者你可以做更多的脚本来获取原始数据。

should print to the console a bunch of <img /> objects with data-uri src= attributes. These can be directly inserted into the page, or you can do more scripting to get at the raw data.

它只适用于嵌入式JPEG对象，但它是一个开始！

It only works for embedded JPEG objects, but it's a start!

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