d62c9181bd
Currently the local `imageCache`, as used in `PartialEvaluator.getOperatorList`, will miss certain cases of repeated images because the caching is *only* done by name (usually using a format such as e.g. "Im0", "Im1", ...). However, in some PDF documents the `/XObject` dictionaries many contain hundreds (or even thousands) of distinctly named images, despite them referring to only a handful of actual image objects (via the XRef table). With these changes we'll now cache *local* images using both name and (where applicable) reference, thus improving re-usage of images resources even further. This patch was tested using the PDF file from [bug 857031](https://bugzilla.mozilla.org/show_bug.cgi?id=857031), i.e. https://bug857031.bmoattachments.org/attachment.cgi?id=732270, with the following manifest file: ``` [ { "id": "bug857031", "file": "../web/pdfs/bug857031.pdf", "md5": "", "rounds": 250, "lastPage": 1, "type": "eq" } ] ``` which gave the following results when comparing this patch against the `master` branch: ``` -- Grouped By browser, page, stat -- browser | page | stat | Count | Baseline(ms) | Current(ms) | +/- | % | Result(P<.05) ------- | ---- | ------------ | ----- | ------------ | ----------- | --- | ----- | ------------- firefox | 0 | Overall | 250 | 2749 | 2656 | -93 | -3.38 | faster firefox | 0 | Page Request | 250 | 3 | 4 | 1 | 50.14 | slower firefox | 0 | Rendering | 250 | 2746 | 2652 | -94 | -3.44 | faster ``` While this is certainly an improvement, since we now avoid re-parsing ~1000 images on the first page, all of the image resources are small enough that the total rendering time doesn't improve that much in this particular case. In pathological cases, such as e.g. the PDF document in issue 4958, the improvements with this patch can be very significant. Looking for example at page 2, from issue 4958, the rendering time drops from ~60 seconds with `master` to ~30 seconds with this patch (obviously still slow, but it really showcases the potential of this patch nicely). Finally, note that there's also potential for additional improvements by re-using `LocalImageCache` instances for e.g. /XObject data of the `Form`-type. However, given that recent changes in this area I purposely didn't want to complicate *this* patch more than necessary.
PDF.js 
PDF.js is a Portable Document Format (PDF) viewer that is built with HTML5.
PDF.js is community-driven and supported by Mozilla Labs. Our goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs.
Contributing
PDF.js is an open source project and always looking for more contributors. To get involved, visit:
- Issue Reporting Guide
- Code Contribution Guide
- Frequently Asked Questions
- Good Beginner Bugs
- Projects
Feel free to stop by our Matrix room for questions or guidance.
Getting Started
Online demo
Please note that the "Modern browsers" version assumes native support for
features such as e.g. async/await, Promise, and ReadableStream.
-
Modern browsers: https://mozilla.github.io/pdf.js/web/viewer.html
-
Older browsers: https://mozilla.github.io/pdf.js/es5/web/viewer.html
Browser Extensions
Firefox
PDF.js is built into version 19+ of Firefox.
Chrome
- The official extension for Chrome can be installed from the Chrome Web Store. This extension is maintained by @Rob--W.
- Build Your Own - Get the code as explained below and issue
gulp chromium. Then open Chrome, go toTools > Extensionand load the (unpackaged) extension from the directorybuild/chromium.
Getting the Code
To get a local copy of the current code, clone it using git:
$ git clone https://github.com/mozilla/pdf.js.git
$ cd pdf.js
Next, install Node.js via the official package or via nvm. You need to install the gulp package globally (see also gulp's getting started):
$ npm install -g gulp-cli
If everything worked out, install all dependencies for PDF.js:
$ npm install
Finally, you need to start a local web server as some browsers do not allow opening
PDF files using a file:// URL. Run:
$ gulp server
and then you can open:
Please keep in mind that this requires an ES6 compatible browser; refer to Building PDF.js for usage with older browsers.
It is also possible to view all test PDF files on the right side by opening:
Building PDF.js
In order to bundle all src/ files into two production scripts and build the generic
viewer, run:
$ gulp generic
This will generate pdf.js and pdf.worker.js in the build/generic/build/ directory.
Both scripts are needed but only pdf.js needs to be included since pdf.worker.js will
be loaded by pdf.js. The PDF.js files are large and should be minified for production.
Using PDF.js in a web application
To use PDF.js in a web application you can choose to use a pre-built version of the library
or to build it from source. We supply pre-built versions for usage with NPM and Bower under
the pdfjs-dist name. For more information and examples please refer to the
wiki page on this subject.
Including via a CDN
PDF.js is hosted on several free CDNs:
- https://www.jsdelivr.com/package/npm/pdfjs-dist
- https://cdnjs.com/libraries/pdf.js
- https://unpkg.com/pdfjs-dist/
Learning
You can play with the PDF.js API directly from your browser using the live demos below:
More examples can be found in the examples folder. Some of them are using the pdfjs-dist package, which can be built and installed in this repo directory via gulp dist-install command.
For an introduction to the PDF.js code, check out the presentation by our contributor Julian Viereck:
More learning resources can be found at:
The API documentation can be found at:
Questions
Check out our FAQs and get answers to common questions:
Talk to us on Matrix:
File an issue:
Follow us on twitter: @pdfjs