The purpose of this description is to provide quick summary on documentation style used in `espressif/esp-idf`_ repository and how to add new documentation.
When documenting code for this repository, please follow `Doxygen style <https://www.stack.nl/~dimitri/doxygen/manual/docblocks.html#specialblock>`_. You are doing it by inserting special commands, for instance ``@param``, into standard comments blocks, for example: ::
Doxygen supports couple of formatting styles. It also gives you great flexibility on level of details to include in documentation. To get familiar with available features, please check data reach and very well organized `Doxygen Manual <https://www.stack.nl/~dimitri/doxygen/manual/index.html>`_.
The ultimate goal is to ensure that all the code is consistently documented, so we can use tools like `Sphinx <http://www.sphinx-doc.org/>`_ and `Breathe <https://breathe.readthedocs.io/>`_ to aid preparation and automatic updates of API documentation when the code changes.
1. Document all building blocks of code: functions, structs, typedefs, enums, macros, etc. Provide enough information on purpose, functionality and limitations of documented items, as you would like to see them documented when reading the code by others.
2. Documentation of function should describe what this function does. If it accepts input parameters and returns some value, all of them should be explained.
3. Do not add a data type before parameter or any other characters besides spaces. All spaces and line breaks are compressed into a single space. If you like to break a line, then break it twice.
7. Overview of functionality of documented header file, or group of files that make a library, should be placed in the same directory in a separate ``README.rst`` file. If directory contains header files for different APIs, then the file name should be ``apiname-readme.rst``.
3. To provide common description to a group of similar functions, enclose them using ``/**@{*/`` and ``/**@}*/`` markup commands::
/**@{*/
/**
* @brief common description of similar functions
*
*/
void first_similar_function (void);
void second_similar_function (void);
/**@}*/
For practical example see :component_file:`nvs_flash/include/nvs.h`.
4. You may want to go even further and skip some code like e.g. repetitive defines or enumerations. In such case enclose the code within ``/** @cond */`` and ``/** @endcond */`` commands. Example of such implementation is provided in :component_file:`driver/include/driver/gpio.h`.
5. Use markdown to make your documentation even more readable. You will add headers, links, tables and more. ::
6. Prepare one or more complete code examples together with description. Place description in a separate file ``README.md`` in specific folder of :idf:`examples` directory.
When linking to examples on GitHub do not use absolute / hadcoded URLs. Instead, use docutils custom roles that will generate links for you. These auto-generated links point to the tree or blob for the git commit ID (or tag) of the repository. This is needed to ensure that links do not get broken when files in master branch are moved around or deleted.
The following roles are provided:
-``:idf:`path``` - points to directory inside ESP-IDF
A check is added to the CI build script, which searches RST files for presence of hard-coded links (identified by tree/master, blob/master, or raw/master part of the URL). This check can be run manually: ``cd docs`` and then ``make gh-linkcheck``.
Switching between documentation in different languages may be done using ``:link_to_translation:`` custom role. The role placed on a page of documentation provides a link to the same page in a language specified as a parameter. Examples below show how to enter links to Chinese and English versions of documentation::
:link_to_translation:`zh_CN:中文版`
:link_to_translation:`en:English`
The language is specified using standard abbreviations like ``en`` or ``zh_CN``. The text after last semicolon is not standardized and may be entered depending on the context where the link is placed, e.g.::
:link_to_translation:`en:see description in English`
Consider adding diagrams and pictures to illustrate described concepts.
Sometimes it is better to add an illustration than writing a lengthy paragraph to describe a complex idea, a data structure or an algorithm. This repository is using `blockdiag <http://blockdiag.com/en/index.html>`_ suite of tools to generate diagram images from simple text files.
With this suite of tools it is possible to generate beautiful diagram images from simple text format (similar to graphviz’s DOT format). The diagram elements are laid out automatically. The diagram code is then converted into ".png" graphics and integrated "behind the scenes" into **Sphinx** documents.
* Slightly more complicated **block diagram** - `Wi-Fi programming model <http://interactive.blockdiag.com/?compression=deflate&src=eJyFk09P40AMxe98CqscIVILq72UIFX8kSoQWy0RHABFTuImFtOZaGYKuyC-O840bagaRI7Pfs7Pz0mmTP5cMJbwynNOa2tKi4sF6zJdmIIUvO_tgTz7UCqToQL03nK29OSCrqUpfeXCVxDD6Gg47tSKuKy8yL9b1dWov1E3E4atWtAcl8qnrsKapGDNUhdUZObfdr2UQp3mRhkrXdpoGq-BGwhQmJFaoSZns_Q2mZxdwUNQ44Eojxqcx_x5cAhzo73jN4pHv55WL7m4u0nSZHLbOeiFtBePR9dvmcxm19sWrGvFOXo2utd4CGH5eHQ8bGfcTy-n6fnfO9jMuOfoksV9bvmFbO-Lr27-JPAQ4oqbGJ62c8iN1pQ3EA4O-lOJTncXDvvupCGdu3vmqFQmSQqm3CIYBx0EWou6pADjQJbw3Bj-h3I4onxpsHrCQLnmoD0yVKgLJXuP1x3GsowPmUpfbay3yH5T7khPoi7NnpU-1nisPdkFyY_gV4x9XB3Y0pHdpfoJ60toURQOtqbYuvpJ1B6zDXYym0qmTVpNnh-fpWcbRA>`_
***Sequence diagram** / ``seqdiag`` - `Scan for a Specific AP in All Channels <http://interactive.blockdiag.com/seqdiag/?compression=deflate&src=eJyVkU1PwzAMhu_7FdburUgQXMomTaPcKIdOIIRQlDVuG1EloUknPsR_J2s2rRsT2nKJ9drvY8ex-C4kr8AWXLFSt8waLBg38D0Cf3jh5Io7qRVMQGmFSS-jqJA1qCpXe51cXwTZGg-pUVa1W8tXQRVY8q5xzNbcoNdb3SmBYqk_9vOlVs7Kr3UJoQmMwgDGMMftWwK4QuU28ZOM7uQm3q_zYTQd5OGl4UtsJmMSE5jCXKtSVl2LUPgpXPvpb4Hj1-RUCPWQ3O_K-wKpX84WMLAcB9B-igCouVLYADnDTA_N9GRzHMdnNMoOG2Vb8-4b4CY6Zr4MT3zOF-k9Sx_TbMHy-Sxjtw9Z-mfRHjEA7hD0X8TPLxU91AQ>`_
Once documentation is ready, follow instruction in :doc:`../api-reference/template` and create a single file, that will merge all individual pieces of prepared documentation. Finally add a link to this file to respective ``.. toctree::`` in ``index.rst`` file located in ``/docs`` folder or subfolders.
1. No worries. All the software you need is well documented. It is also open source and free. Start by checking `Sphinx <http://www.sphinx-doc.org/>`_ documentation. If you are not clear how to write using rst markup language, see `reStructuredText Primer <http://www.sphinx-doc.org/en/stable/rest.html>`_. You can also use markdown (.md) files, and find out about more about the specific markdown syntax that we use on`Recommonmark parser's documentation page <https://recommonmark.readthedocs.io/en/latest/>`_.
2. Check the source files of this documentation to understand what is behind of what you see now on the screen. Sources are maintained on GitHub in `espressif/esp-idf`_ repository in :idf:`docs` folder. You can go directly to the source file of this page by scrolling up and clicking the link in the top right corner. When on GitHub, see what's really inside, open source files by clicking ``Raw`` button.
* Install `Sphinx <http://www.sphinx-doc.org/>`_, `Breathe <https://breathe.readthedocs.io/>`_, `Blockdiag <http://blockdiag.com/en/index.html>`_ and `Doxygen <https://www.stack.nl/~dimitri/doxygen/>`_ to build it locally, see chapter below.
* Set up an account on `Read the Docs <https://readthedocs.org/>`_ and build documentation in the cloud. Read the Docs provides document building and hosting for free and their service works really quick and great.
4. To preview documentation before building, use `Sublime Text <https://www.sublimetext.com/>`_ editor together with `OmniMarkupPreviewer <https://github.com/timonwong/OmniMarkupPreviewer>`_ plugin.
The package "sphinx_rtd_theme" is added to have the same "look and feel" of `ESP32 Programming Guide <https://docs.espressif.com/projects/esp-idf/en/latest/index.html>`_ documentation like on the "Read the Docs" hosting site.
Do not worry about being confronted with several packages to install. Besides Doxygen, all remaining packages are written in Python. Therefore installation of all of them is combined into one simple step.
If you are installing on Windows system (Linux and MacOS users should skip this note), **before** going further, execute two extra steps below. These steps are required to install dependencies of "blockdiag" discussed under :ref:`add-illustrations`.
A downside of Windows installation is that fonts of the `blockdiag pictures <add-illustrations>` do not render correctly, you will see some random characters instead. Until this issue is fixed, you can use the `interactive shell`_ to see how the complete picture looks like.
This may take couple of minutes. After completion, documentation will be placed in ``~/esp/esp-idf/docs/en/_build/html`` folder. To see it, open ``index.html`` in a web browser.
