如何使用NodeJS替换PDF文件中的字符串? [英] How do I replace a string in a PDF file using NodeJS?
问题描述
我有一个模板PDF文件,我想替换一些标记字符串以生成新的PDF文件并保存.最好/最简单的方法是什么?我不需要添加图形或任何花哨的东西,只需简单的文本替换即可,所以我不需要任何复杂的东西.
I have a template PDF file, and I want to replace some marker strings to generate new PDF files and save them. What's the best/simplest way to do this? I don't need to add graphics or anything fancy, just a simple text replacement, so I don't want anything too complicated.
谢谢!
刚刚找到 HummusJS ,我将看看是否可以取得进展并将其发布在这里.
Just found HummusJS, I'll see if I can make progress and post it here.
推荐答案
我通过搜索找到了这个问题,所以我认为它值得回答.我在这里找到了BrighTide的答案: https://github.com/galkahana/HummusJS/issues/71#issuecomment-275956347
I found this question by searching, so I think it deserves the answer. I found the answer by BrighTide here: https://github.com/galkahana/HummusJS/issues/71#issuecomment-275956347
基本上,有一个非常强大的Hummus软件包,它使用C ++编写的库(当然是跨平台的).我认为可以在github注释中给出的答案可以像这样进行功能化:
Basically, there is this very powerful Hummus package which uses library written in C++ (crossplatform of course). I think the answer given in that github comment can be functionalized like this:
var hummus = require('hummus');
/**
* Returns a byteArray string
*
* @param {string} str - input string
*/
function strToByteArray(str) {
var myBuffer = [];
var buffer = new Buffer(str);
for (var i = 0; i < buffer.length; i++) {
myBuffer.push(buffer[i]);
}
return myBuffer;
}
function replaceText(sourceFile, targetFile, pageNumber, findText, replaceText) {
var writer = hummus.createWriterToModify(sourceFile, {
modifiedFilePath: targetFile
});
var modifier = new hummus.PDFPageModifier(writer, pageNumber);
var sourceParser = writer.createPDFCopyingContextForModifiedFile().getSourceDocumentParser();
var pageObject = sourceParser.parsePage(pageNumber);
var textObjectId = pageObject.getDictionary().toJSObject().Contents.getObjectID();
var textStream = sourceParser.queryDictionaryObject(pageObject.getDictionary(), 'Contents');
//read the original block of text data
var data = [];
var readStream = sourceParser.startReadingFromStream(textStream);
while(readStream.notEnded()){
Array.prototype.push.apply(data, readStream.read(10000));
}
var string = new Buffer(data).toString().replace(findText, replaceText);
//Create and write our new text object
var objectsContext = writer.getObjectsContext();
objectsContext.startModifiedIndirectObject(textObjectId);
var stream = objectsContext.startUnfilteredPDFStream();
stream.getWriteStream().write(strToByteArray(string));
objectsContext.endPDFStream(stream);
objectsContext.endIndirectObject();
writer.end();
}
// replaceText('source.pdf', 'output.pdf', 0, /REPLACEME/g, 'My New Custom Text');
更新:
编写示例时使用的版本为1.0.83
,最近可能会有所变化.
UPDATE:
The version used at the time of writing an example was 1.0.83
, things might change recently.
更新2:
最近,我遇到另一个字体不同的PDF文件的问题.由于某种原因,文本被分成小块,即字符串QWERTYUIOPASDFGHJKLZXCVBNM1234567890-
被表示为-286(Q)9(WER)24(T)-8(YUIOP)116(ASDF)19(GHJKLZX)15(CVBNM1234567890-)
我不知道除了组成正则表达式外还要做些什么.所以代替这一行:
UPDATE 2:
Recently I got an issue with another PDF file which had a different font. For some reason the text got split into small chunks, i.e. string QWERTYUIOPASDFGHJKLZXCVBNM1234567890-
got represented as -286(Q)9(WER)24(T)-8(YUIOP)116(ASDF)19(GHJKLZX)15(CVBNM1234567890-)
I had no idea what else to do rather than make up a regex.. So instead of this one line:
var string = new Buffer(data).toString().replace(findText, replaceText);
我现在有这样的东西:
var string = Buffer.from(data).toString();
var characters = REPLACE_ME;
var match = [];
for (var a = 0; a < characters.length; a++) {
match.push('(-?[0-9]+)?(\\()?' + characters[a] + '(\\))?');
}
string = string.replace(new RegExp(match.join('')), function(m, m1) {
// m1 holds the first item which is a space
return m1 + '( ' + REPLACE_WITH_THIS + ')';
});
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