README.md - pdfium - Git at Google


            
            # PDFium


            ## Prerequisites


            PDFium uses the same build tooling as Chromium. See the platform-specific

            
            Chromium build instructions to get started, but replace Chromium's

            
            "Get the code" instructions with [PDFium's](#get-the-code).


            *   [Chromium Linux build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/linux/build_instructions.md)

            
            *   [Chromium Mac build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/mac_build_instructions.md)

            
            *   [Chromium Windows build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/windows_build_instructions.md)


            ### 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.


            ### Compilers supported


            PDFium aims to be compliant with the [Chromium policy](https://chromium.googlesource.com/chromium/src/+/main/docs/toolchain_support.md#existing-toolchain-support).


            Currently this means Clang. Former MSVC users should consider using clang-cl

            
            if needed. Community-contributed patches for gcc will be allowed. No MSVC

            
            patches will be taken.


            #### 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](#generate-the-build-files) 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 the following example,

            
            the directory name is "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

            
            ```


            On Linux, additional build dependencies need to be installed by running the

            
            following from the `pdfium` directory.


            ```

            
            ./build/install-build-deps.sh

            
            ```


            ## Generate the build files


            PDFium uses 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_remoteexec = false # Approved users only.  Do necessary setup & authentication first.

            
            is_debug = true  # Enable debugging features.


            # Set true to enable experimental Skia backend.

            
            pdf_use_skia = false


            # Set true to enable experimental Fontations backend.

            
            pdf_enable_fontations = false


            pdf_enable_xfa = true  # Set false to remove XFA support (implies JS support).

            
            pdf_enable_v8 = true  # Set false to remove Javascript support.

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

            
            ```


            In order to minimize the build time for embedder applications, test executables

            
            like `pdfium_test` are not built by default. To build these, add the argument

            
            `pdf_is_standalone = true`.


            By default, the entire project builds with C++20.


            By default, PDFium expects to build with a clang compiler that provides

            
            additional chrome plugins. To build against a vanilla one lacking these,

            
            one must set

            
            `clang_use_chrome_plugins = false`.


            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 standalone test 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 standalone test 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/main/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. The PDFium project endeavors 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


            PDFium uses this [bug tracker](https://crbug.com/pdfium/new), but for security

            
            bugs, please use

            
            [Chromium's security bug template](https://crbug.com/new?component=1586257&noWizard=True&template=1922342).


            ## Contributing code


            See the [CONTRIBUTING](CONTRIBUTING.md) document for more information on

            
            contributing to the PDFium project.
	# PDFium

	## Prerequisites

	PDFium uses the same build tooling as Chromium. See the platform-specific
	Chromium build instructions to get started, but replace Chromium's
	"Get the code" instructions with [PDFium's](#get-the-code).

	* [Chromium Linux build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/linux/build_instructions.md)
	* [Chromium Mac build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/mac_build_instructions.md)
	* [Chromium Windows build instructions](https://chromium.googlesource.com/chromium/src/+/main/docs/windows_build_instructions.md)

	### 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.

	### Compilers supported

	PDFium aims to be compliant with the [Chromium policy](https://chromium.googlesource.com/chromium/src/+/main/docs/toolchain_support.md#existing-toolchain-support).

	Currently this means Clang. Former MSVC users should consider using clang-cl
	if needed. Community-contributed patches for gcc will be allowed. No MSVC
	patches will be taken.

	#### 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](#generate-the-build-files) 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 the following example,
	the directory name is "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
	```

	On Linux, additional build dependencies need to be installed by running the
	following from the `pdfium` directory.

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

	## Generate the build files

	PDFium uses 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_remoteexec = false # Approved users only. Do necessary setup & authentication first.
	is_debug = true # Enable debugging features.

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

	# Set true to enable experimental Fontations backend.
	pdf_enable_fontations = false

	pdf_enable_xfa = true # Set false to remove XFA support (implies JS support).
	pdf_enable_v8 = true # Set false to remove Javascript support.
	is_component_build = false # Disable component build (Though it should work)
	```

	In order to minimize the build time for embedder applications, test executables
	like `pdfium_test` are not built by default. To build these, add the argument
	`pdf_is_standalone = true`.

	By default, the entire project builds with C++20.

	By default, PDFium expects to build with a clang compiler that provides
	additional chrome plugins. To build against a vanilla one lacking these,
	one must set
	`clang_use_chrome_plugins = false`.

	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 standalone test 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 standalone test 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/main/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. The PDFium project endeavors 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

	PDFium uses this [bug tracker](https://crbug.com/pdfium/new), but for security
	bugs, please use
	[Chromium's security bug template](https://crbug.com/new?component=1586257&noWizard=True&template=1922342).

	## Contributing code

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