README.md - pdfium.git - Git at Google

 # PDFium

 ## Prerequisites

 Get the Chromium depot\_tools via the
 [instructions](https://www.chromium.org/developers/how-tos/install-depot-tools).
 This provides the gclient utility needed below and many other tools needed for
 PDFium development.

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


 ### Windows development

 PDFium uses the same build tool as Chromium:

 #### Open source contributors
 Please refer to
 [Chromium's Visual Studio set up](https://chromium.googlesource.com/chromium/src/+/master/docs/windows_build_instructions.md#visual-studio)
 for requirements and instructions on build environment configuration.

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

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

 ### CPU Architectures supported

 The default architecture for Windows, Linux, and Mac is "`x64`". On Windows,
 "`x86`" is also supported. GN parameter "`target_cpu = "x86"`" can be used to
 override the default value. If you specify Android build, the default CPU
 architecture will be "`arm`".

 It is expected that there are still some places lurking in the code which will
 not function properly on big-endian architectures. Bugs and/or patches are
 welcome, however providing this support is **not** a priority at this time.

 #### 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 [Generate the build files](#GenBuild) step 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
 ```

 Additional build dependencies need to be installed by running the following from
 the `pdfium` directory.

 ```
 ./build/install-build-deps.sh
 ```

 ## Generate the build files

 We use GN to generate the build files and [Ninja](https://ninja-build.org/)
 to execute the build files.  Both of these are included with the
 depot\_tools checkout.

 ### 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 launch an editor in which you can set the following arguments.
 By convention, `<directory>` should be named `out/foo`, and some tools / test
 support code only works if one follows this convention.
 A typical `<directory>` name is `out/Debug`.

 ```
 use_goma = true  # Googlers only. Make sure goma is installed and running first.
 is_debug = true  # Enable debugging features.

 # Set true to enable experimental Skia backend.
 pdf_use_skia = false
 # Set true to enable experimental Skia backend (paths only).
 pdf_use_skia_paths = false

 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.
 is_component_build = false # Disable component build (Though it should work)

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

 For sample applications like `pdfium_test` to build, one must set
 `pdf_is_standalone = true`.

 By default, the entire project builds with C++14. When building with the
 experimental Skia backend, Skia itself it built with C++17.

 When complete the arguments will be stored in `<directory>/args.gn`, and
 GN will automatically use the new arguments to generate build files.
 Should your files fail to generate, please double-check that you have set
 use\_sysroot as indicated above.

 ## Building the code

 You can build the sample program by running: `ninja -C <directory> pdfium_test`
 You can build the entire product (which includes a few unit tests) by running:
 `ninja -C <directory> pdfium_all`.

 ## 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`.
 Run `pdfium_test --help` to see all the options.

 ## 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.

 ### Pixel Tests

 If your change affects rendering, a pixel test should be added. Simply add a
 `.in` or `.pdf` file in `testing/resources/pixel` and the pixel runner will
 pick it up at the next run.

 Make sure that your test case doesn't have any copyright issues. It should also
 be a minimal test case focusing on the bug that renders the same way in many
 PDF viewers. Try to avoid binary data in streams by using the `ASCIIHexDecode`
 simply because it makes the PDF more readable in a text editor.

 To try out your new test, you can call the `run_pixel_tests.py` script:

 ```bash
 $ ./testing/tools/run_pixel_tests.py your_new_file.in
 ```

 To generate the expected image, you can use the `make_expected.sh` script:

 ```bash
 $ ./testing/tools/make_expected.sh your_new_file.pdf
 ```

 Please make sure to have `optipng` installed which optimized the file size of
 the resulting png.

 ### `.in` files

 `.in` files are PDF template files. PDF files contain many byte offsets that
 have to be kept correct or the file won't be valid. The template makes this
 easier by replacing the byte offsets with certain keywords.

 This saves space and also allows an easy way to reduce the test case to the
 essentials as you can simply remove everything that is not necessary.

 A simple example can be found [here](https://pdfium.googlesource.com/pdfium/+/refs/heads/master/testing/resources/rectangles.in).

 To transform this into a PDF, you can use the `fixup_pdf_template.py` tool:

 ```bash
 $ ./testing/tools/fixup_pdf_template.py your_file.in
 ```

 This will create a `your_file.pdf` in the same directory as `your_file.in`.

 There is no official style guide for the .in file, but a consistent style is
 preferred simply to help with readability. If possible, object numbers should
 be consecutive and `/Type` and `/SubType` should be on top of a dictionary to
 make object identification easier.

 ## Embedding PDFium in your own projects

 The public/ directory contains header files for the APIs available for use by
 embedders of PDFium. We endeavor to keep these as stable as possible.

 Outside of the public/ directory, code may change at any time, and embedders
 should not directly call these routines.

 ## Code Coverage

 Code coverage reports for PDFium can be generated in Linux development
 environments. Details can be found [here](/docs/code-coverage.md).

 Chromium provides code coverage reports for PDFium
 [here](https://chromium-coverage.appspot.com/). PDFium is located in
 `third_party/pdfium` in Chromium's source code.
 This includes code coverage from PDFium's fuzzers.

 ## Waterfall

 The current health of the source tree can be found
 [here](https://ci.chromium.org/p/pdfium/g/main/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://bugs.chromium.org/p/pdfium/issues/list), but for security
 bugs, please use
 [Chromium's security bug template](https://bugs.chromium.org/p/chromium/issues/entry?template=Security%20Bug)
 and add the "Cr-Internals-Plugins-PDF" label.

 ## Contributing code

 See the [CONTRIBUTING](CONTRIBUTING.md) document for more information on
 contributing to the PDFium project.
	# PDFium

	## Prerequisites

	Get the Chromium depot\_tools via the
	[instructions](https://www.chromium.org/developers/how-tos/install-depot-tools).
	This provides the gclient utility needed below and many other tools needed for
	PDFium development.

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


	### Windows development

	PDFium uses the same build tool as Chromium:

	#### Open source contributors
	Please refer to
	[Chromium's Visual Studio set up](https://chromium.googlesource.com/chromium/src/+/master/docs/windows_build_instructions.md#visual-studio)
	for requirements and instructions on build environment configuration.

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

	Compilation is done through Ninja, not Visual Studio.

	### CPU Architectures supported

	The default architecture for Windows, Linux, and Mac is "`x64`". On Windows,
	"`x86`" is also supported. GN parameter "`target_cpu = "x86"`" can be used to
	override the default value. If you specify Android build, the default CPU
	architecture will be "`arm`".

	It is expected that there are still some places lurking in the code which will
	not function properly on big-endian architectures. Bugs and/or patches are
	welcome, however providing this support is not a priority at this time.

	#### 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 [Generate the build files](#GenBuild) step 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
	```

	Additional build dependencies need to be installed by running the following from
	the `pdfium` directory.

	```
	./build/install-build-deps.sh
	```

	## Generate the build files

	We use GN to generate the build files and [Ninja](https://ninja-build.org/)
	to execute the build files. Both of these are included with the
	depot\_tools checkout.

	### 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 launch an editor in which you can set the following arguments.
	By convention, `<directory>` should be named `out/foo`, and some tools / test
	support code only works if one follows this convention.
	A typical `<directory>` name is `out/Debug`.

	```
	use_goma = true # Googlers only. Make sure goma is installed and running first.
	is_debug = true # Enable debugging features.

	# Set true to enable experimental Skia backend.
	pdf_use_skia = false
	# Set true to enable experimental Skia backend (paths only).
	pdf_use_skia_paths = false

	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.
	is_component_build = false # Disable component build (Though it should work)

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

	For sample applications like `pdfium_test` to build, one must set
	`pdf_is_standalone = true`.

	By default, the entire project builds with C++14. When building with the
	experimental Skia backend, Skia itself it built with C++17.

	When complete the arguments will be stored in `<directory>/args.gn`, and
	GN will automatically use the new arguments to generate build files.
	Should your files fail to generate, please double-check that you have set
	use\_sysroot as indicated above.

	## Building the code

	You can build the sample program by running: `ninja -C <directory> pdfium_test`
	You can build the entire product (which includes a few unit tests) by running:
	`ninja -C <directory> pdfium_all`.

	## 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`.
	Run `pdfium_test --help` to see all the options.

	## 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.

	### Pixel Tests

	If your change affects rendering, a pixel test should be added. Simply add a
	`.in` or `.pdf` file in `testing/resources/pixel` and the pixel runner will
	pick it up at the next run.

	Make sure that your test case doesn't have any copyright issues. It should also
	be a minimal test case focusing on the bug that renders the same way in many
	PDF viewers. Try to avoid binary data in streams by using the `ASCIIHexDecode`
	simply because it makes the PDF more readable in a text editor.

	To try out your new test, you can call the `run_pixel_tests.py` script:

	```bash
	$ ./testing/tools/run_pixel_tests.py your_new_file.in
	```

	To generate the expected image, you can use the `make_expected.sh` script:

	```bash
	$ ./testing/tools/make_expected.sh your_new_file.pdf
	```

	Please make sure to have `optipng` installed which optimized the file size of
	the resulting png.

	### `.in` files

	`.in` files are PDF template files. PDF files contain many byte offsets that
	have to be kept correct or the file won't be valid. The template makes this
	easier by replacing the byte offsets with certain keywords.

	This saves space and also allows an easy way to reduce the test case to the
	essentials as you can simply remove everything that is not necessary.

	A simple example can be found [here](https://pdfium.googlesource.com/pdfium/+/refs/heads/master/testing/resources/rectangles.in).

	To transform this into a PDF, you can use the `fixup_pdf_template.py` tool:

	```bash
	$ ./testing/tools/fixup_pdf_template.py your_file.in
	```

	This will create a `your_file.pdf` in the same directory as `your_file.in`.

	There is no official style guide for the .in file, but a consistent style is
	preferred simply to help with readability. If possible, object numbers should
	be consecutive and `/Type` and `/SubType` should be on top of a dictionary to
	make object identification easier.

	## Embedding PDFium in your own projects

	The public/ directory contains header files for the APIs available for use by
	embedders of PDFium. We endeavor to keep these as stable as possible.

	Outside of the public/ directory, code may change at any time, and embedders
	should not directly call these routines.

	## Code Coverage

	Code coverage reports for PDFium can be generated in Linux development
	environments. Details can be found [here](/docs/code-coverage.md).

	Chromium provides code coverage reports for PDFium
	[here](https://chromium-coverage.appspot.com/). PDFium is located in
	`third_party/pdfium` in Chromium's source code.
	This includes code coverage from PDFium's fuzzers.

	## Waterfall

	The current health of the source tree can be found
	[here](https://ci.chromium.org/p/pdfium/g/main/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://bugs.chromium.org/p/pdfium/issues/list), but for security
	bugs, please use
	[Chromium's security bug template](https://bugs.chromium.org/p/chromium/issues/entry?template=Security%20Bug)
	and add the "Cr-Internals-Plugins-PDF" label.

	## Contributing code

	See the [CONTRIBUTING](CONTRIBUTING.md) document for more information on
	contributing to the PDFium project.