# PDFium

## News

As of 2016-05-04, GN is used to generate build files replacing GYP. GYP
support will remain until it is disabled in Chromium and then will be removed
from PDFium.

As of 2016-04-28, the Visual Studio toolchain from depot_tools is used as the
default Windows toolchain for Googlers. Please set DEPOT_TOOLS_WIN_TOOLCHAIN=0
if you need to use the system toolchain. See
[Windows development subsection](#WinDev) for details.


## Prerequisites

Get the chromium depot tools via the instructions at
http://www.chromium.org/developers/how-tos/install-depot-tools (this provides
the gclient utilty needed below).

Also install Python, Subversion, and Git and make sure they're in your path.


###<a name="WinDev"></a> Windows development

PDFium uses a similar Windows toolchain as Chromium:

#### Open source contributors
Visual Studio 2015 Update 2 or later is highly recommended.

Run `set DEPOT_TOOLS_WIN_TOOLCHAIN=0`, or set that variable in your global
environment.

Compilation is done through ninja, **not** Visual Studio.


#### Google employees

Run: `download_from_google_storage --config` and follow the
authentication instructions. **Note that you must authenticate with your
@google.com credentials**. Enter "0" if asked for a project-id.

Once you've done this, the toolchain will be installed automatically for
you in [the step](#GenBuild) below.

The toolchain will be in `depot_tools\win_toolchain\vs_files\<hash>`, and windbg
can be found in `depot_tools\win_toolchain\vs_files\<hash>\win_sdk\Debuggers`.

If you want the IDE for debugging and editing, you will need to install
it separately, but this is optional and not needed for building PDFium.


## Get the code

The name of the top-level directory does not matter. In our examples, we use
"repo". This directory must not have been used before by `gclient config` as
each directory can only house a single gclient configuration.

```
mkdir repo
cd repo
gclient config --unmanaged https://pdfium.googlesource.com/pdfium.git
gclient sync
cd pdfium
```

##<a name="GenBuild"></a> Generate the build files

We use GN to generate the build files and
[Ninja](http://martine.github.io/ninja/) (also included with the depot\_tools
checkout) to execute the build files.

```
gn gen <directory>
```

If you want to set <directory> to `out/Debug` or `out/Release` you'll need to
export `GYP_PDFIUM_NO_ACTION=1` to stop `gclient sync` from executing GYP
and overwritting your build files.

###<a name="BuildConfig"></a> Selecting build configuration

PDFium may be built either with or without JavaScript support, and with
or without XFA forms support.  Both of these features are enabled by
default. Also note that the XFA feature requires JavaScript.

Configuration is done by executing `gn args <directory>` to configure the build.
This will lauch an editor in which you can set the following arguments.

```
use_goma = true  # Googlers only.
is_debug = true  # Enable debugging features.

pdf_use_skia = false  # Set true to enable experimental skia backend.

pdf_enable_xfa = true # Set false to remove XFA support (implies JS support).
pdf_enable_v8 = true  # Set false to remove Javascript support.
pdf_is_standalone = true  # Set for a non-embedded build.

clang_use_chrome_plugins = false  # Currently must be false.
```

When complete the arguments will be stored in `<directory>/args.gn`.

## Building the code

If you used Ninja, you can build the sample program by:
`ninja -C <directory>/pdfium_test` You can build the entire product (which
includes a few unit tests) by: `ninja -C <directory>`.


## Running the sample program

The pdfium\_test program supports reading, parsing, and rasterizing the pages of
a .pdf file to .ppm or .png output image files (windows supports two other
formats). For example: `<directory>/pdfium_test --ppm path/to/myfile.pdf`. Note
that this will write output images to `path/to/myfile.pdf.<n>.ppm`.

## Testing

There are currently several test suites that can be run:

 * pdfium\_unittests
 * pdfium\_embeddertests
 * testing/tools/run\_corpus\_tests.py
 * testing/tools/run\_javascript\_tests.py
 * testing/tools/run\_pixel\_tests.py

It is possible the tests in the `testing` directory can fail due to font
differences on the various platforms. These tests are reliable on the bots. If
you see failures, it can be a good idea to run the tests on the tip-of-tree
checkout to see if the same failures appear.

## Waterfall

The current health of the source tree can be found at
http://build.chromium.org/p/client.pdfium/console

## Community

There are several mailing lists that are setup:

 * [PDFium](https://groups.google.com/forum/#!forum/pdfium)
 * [PDFium Reviews](https://groups.google.com/forum/#!forum/pdfium-reviews)
 * [PDFium Bugs](https://groups.google.com/forum/#!forum/pdfium-bugs)

Note, the Reviews and Bugs lists are typically read-only.

## Bugs

 We use this
[bug tracker](https://code.google.com/p/pdfium/issues/list), but for security
bugs, please use [Chromium's security bug template]
(https://code.google.com/p/chromium/issues/entry?template=Security%20Bug)
and add the "Cr-Internals-Plugins-PDF" label.

## Contributing code

For contributing code, we will follow
[Chromium's process](http://dev.chromium.org/developers/contributing-code)
as much as possible. The main exceptions is:

1. Code has to conform to the existing style and not Chromium/Google style.