Pdf.js: rendering a pdf file using a base64 file source instead of url

I'm trying to render a page from a pdf with pdf.js

Normally, using a url, I can do this:

PDFJS.getDocument("http://www.server.com/file.pdf").then(function getPdfHelloWorld(pdf) {
//
// Fetch the first page
//
pdf.getPage(1).then(function getPageHelloWorld(page) {
var scale = 1.5;
var viewport = page.getViewport(scale);


//
// Prepare canvas using PDF page dimensions
//
var canvas = document.getElementById('the-canvas');
var context = canvas.getContext('2d');
canvas.height = viewport.height;
canvas.width = viewport.width;


//
// Render PDF page into canvas context
//
page.render({canvasContext: context, viewport: viewport});
});
});

But in this case, I have the file in base64 rather than an url:

data:application/pdf;base64,JVBERi0xLjUKJdDUxdgKNSAwIG9iaiA8PAovTGVuZ3RoIDE2NjUgICAgICAKL0ZpbHRlciAvRmxhdGVEZWNvZGUKPj4Kc3RyZWFtCnjarVhLc9s2...

How this can be done?

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最佳答案

from the sourcecode at http://mozilla.github.com/pdf.js/build/pdf.js

/**
* This is the main entry point for loading a PDF and interacting with it.
* NOTE: If a URL is used to fetch the PDF data a standard XMLHttpRequest(XHR)
* is used, which means it must follow the same origin rules that any XHR does
* e.g. No cross domain requests without CORS.
*
* @param {string|TypedAray|object} source Can be an url to where a PDF is
* located, a typed array (Uint8Array) already populated with data or
* and parameter object with the following possible fields:
*  - url   - The URL of the PDF.
*  - data  - A typed array with PDF data.
*  - httpHeaders - Basic authentication headers.
*  - password - For decrypting password-protected PDFs.
*
* @return {Promise} A promise that is resolved with {PDFDocumentProxy} object.
*/

So a standard XMLHttpRequest(XHR) is used for retrieving the document. The Problem with this is that XMLHttpRequests do not support data: uris (eg. data:application/pdf;base64,JVBERi0xLjUK...).

But there is the possibility of passing a typed Javascript Array to the function. The only thing you need to do is to convert the base64 string to a Uint8Array. You can use this function found at https://gist.github.com/1032746

var BASE64_MARKER = ';base64,';


function convertDataURIToBinary(dataURI) {
var base64Index = dataURI.indexOf(BASE64_MARKER) + BASE64_MARKER.length;
var base64 = dataURI.substring(base64Index);
var raw = window.atob(base64);
var rawLength = raw.length;
var array = new Uint8Array(new ArrayBuffer(rawLength));


for(var i = 0; i < rawLength; i++) {
array[i] = raw.charCodeAt(i);
}
return array;
}

tl;dr

var pdfAsDataUri = "data:application/pdf;base64,JVBERi0xLjUK..."; // shortened
var pdfAsArray = convertDataURIToBinary(pdfAsDataUri);
PDFJS.getDocument(pdfAsArray)
小开

Used the Accepted Answer to do a check for IE and convert the dataURI to UInt8Array; an accepted form by PDFJS 

        Ext.isIE ? pdfAsDataUri = me.convertDataURIToBinary(pdfAsDataUri): '';


convertDataURIToBinary: function(dataURI) {
var BASE64_MARKER = ';base64,',
base64Index = dataURI.indexOf(BASE64_MARKER) + BASE64_MARKER.length,
base64 = dataURI.substring(base64Index),
raw = window.atob(base64),
rawLength = raw.length,
array = new Uint8Array(new ArrayBuffer(rawLength));


for (var i = 0; i < rawLength; i++) {
array[i] = raw.charCodeAt(i);
}
return array;
},

小开

According to the examples base64 encoding is directly supported, although I've not tested it myself. Take your base64 string (derived from a file or loaded with any other method, POST/GET, websockets etc), turn it to a binary with atob, and then parse this to getDocument on the PDFJS API likePDFJS.getDocument({data: base64PdfData}); Codetoffel answer does work just fine for me though.


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