SDK Docs Style Guide

This document describes the writing style used in authoring open-source IntelliJ Platform SDK documentation. Before you begin, please read this page thoroughly, as well as the Code of Conduct and License documents. Please see also Contributing to the IntelliJ Platform SDK for some general remarks. For information about contributing to the IntelliJ Platform itself, please visit Contributing to the IntelliJ Platform.

First and foremost, we should keep in mind our audience and their objectives: Someone reading technical content is usually looking to answer a specific question. That question might be broad or narrowly-focused, but either way, our goal is to provide answers without distraction.

The style of the IntelliJ Platform SDK documentation is captured by using a markup language named Markdown.

To verify grammar and correct spelling, it is highly recommended to use Grazie Professional plugin to highlight any issues on-the-fly in the IDE.

Documentation Markup

The documentation project is using Writerside, so the plugin should be installed to have full support in the IDE. The topic files themselves are Markdown files (*.md) using some Writerside-specific custom tags (see below).

Page Format

Each Markdown file must start with a copyright notice, formatted using HTML comment notation:

<!-- Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license. -->

It must be followed by a header defining its title using the level 1 heading:

# Contributing to the IntelliJ Platform SDK

The page title should be as concise as possible, so it can be reused in the Table of Contents as is.

Excerpt

Every page should provide a short excerpt (usually one sentence) using dedicated <link-summary> tag before the main page contents:

Highlighted Links

A page can highlight related topics and other important links before the actual content using <tldr> tag. Links must be grouped using " Bold Category Name: link1, link2, [...]" (Example).

Use Reference to link to other topics, Code to link to code/files, Platform UI Guidelines for links to IntelliJ Platform UI Guidelines, and Product Help for links to IntelliJ IDEA Help.

Introductory Text

Do not use headings like Introduction, Overview, etc. for any introductory text.

Content Style

Terminology

Consistent terminology helps the reader grasp new concepts more quickly:

The open-source code in the GitHub repository intellij-community is known as the IntelliJ Platform. Use the full phrase in the SDK documentation.
IDEs based on the IntelliJ Platform are described as IntelliJ Platform-based IDEs. Once that term is used on a page, authors may use IDEs.
When referring to JetBrains products always use the full name such as IntelliJ IDEA Ultimate Edition. However, only use product names when extensibility or functionality is particular to a product.

Text Format Conventions

Start every sentence on a new line. For very long sentences, add additional line breaks after ,, : or other sensible places. Very long links should also be on a separate line.

Consistent text styles are used to standardize references and keywords:

Menu paths are wrapped using <ui-path> with pipe characters separating each level: <ui-path>Settings | Editor</ui-path>: Settings | Editor Inside tables, use | instead of | to prevent escaping problems.
User interface element names like labels, buttons, checkboxes, etc. are wrapped using <control>: Press <control>Continue</continue>: Press Continue
Non-code keywords and quotations, or the names of non-code files are formatted as italic style: _Theme_ (Theme), _README.md_ (README.md.) Examples of this file type include LICENSE.txt and README.md.
Code keywords and classnames are formatted as code style: `interface`: interface, `AnAction`: AnAction, `name` attribute: name attribute.
Filenames are wrapped using <path>: <path>build.gradle.kts</path> build.gradle.kts.
File formats are shown as all capital letters: PNG and XML.
Filename extensions are not capitalized when part of a full filename, path, or URL: plugin.xml.
Keyboard shortcuts are wrapped using <shortcut>: press <shortcut>Alt+Insert</shortcut> becomes "press Alt+Insert ".
See Guidelines for Highlighting Syntax for best practices for representing code fragments.
See Links to IntelliJ Platform Source for more details about representing names of source files in links.

Links

Links are handled as standard Markdown links and can be anchored to external sites, pages within the site, or headings in the pages.

When a Markdown header is converted to an HTML header, it is assigned an ID so that it can be linked. For example, ## Basics gets the ID of basics, and can be linked either on the same page or cross-page as described below.

In some cases (e.g., the same heading text appears multiple times on the same page), it is necessary to specify a distinct ID manually:

## Task 1
### Properties
{#task1-properties}
[...]

## Task 2
### Properties
{#task2-properties}
[...]

General Links

General Markdown links have the default Markdown link style:

[Gradle](https://gradle.org) (Gradle) links to an external site, such as companies, articles, etc. If URL contains % character, append {ignore-vars="true"}.
Linking to pages and page sections within the SDK documentation:
- [Page Title](page.md) or [](page.md) (use page title as link text) links to an SDK doc page (all located under /topics). Note that the extension is .md, NOT .html.
- Specific sections on pages in the SDK documentation are linked by using section anchors. The anchor name will be all lower case, and spaces are replaced with -, e.g. ## Page setup becomes #page-setup. Once the anchor (#) character of the link is entered, the IDE code completion feature shows the available sections.
  - [Link to a section on the current page](#another-section) links to a heading on the current page.
  - [Link to the section on another page](other_page.md#another-section) links to a heading on another page.
If the desired link label is the same as an SDK doc page or section title, leave the label part empty, e.g., [](test-page.md) or [](test-page.md#section-1). The empty link label will be automatically filled with the actual page or section title.

Links to IntelliJ Platform Source

Links to files in the IntelliJ Platform (intellij-community) repository use %\gh-ic% prefix instead of the full URL to the repository. Links to files in source code packages in other GitHub repositories follow much the same rules, except the links use a different custom gh-... prefix defined in v.list.

[README.md](%\gh-ic%/README.md) links to general, non-code information files. (README.md) Examples of this file type include LICENSE.txt and README.md.
[IdeaPlugin.xml](%\gh-ic%/community-resources/resources/META-INF/IdeaPlugin.xml) links to declarative source code files, use code style. (IdeaPlugin.xml) Examples of this file type include: settings.gradle, plugin.xml or theme_basics.theme.json.
[`AnAction`](%\gh-ic%/platform/editor-ui-api/src/com/intellij/openapi/actionSystem/AnAction.java) links to source files for code objects like interfaces and classes, use code style but without the file extension. (AnAction) Examples of this file type include Java and Kotlin sources.
- Note the use of `` characters surrounding the class name in the link.
- When linking to an API in this manner, the FQN isn't necessary in the link.
- No file extension (*.java, *.kt, *.py, etc.) is used by convention.
- Be judicious when using such links. Generally, only one link is needed for a given file on a documentation page.

Guidelines for Highlighting Syntax

In-paragraph code fragments and IntelliJ Platform APIs are formatted according to the following rules.

Code

Avoid using qualifiers like " Foo interface" or " Foo abstract class". Instead, refer to Foo.
The FQN is used for the first reference to an interface, class, or package on a page. Rather than AnAction, introduce it as com.intellij.openapi.actionSystem.AnAction. Subsequent references on the page can be AnAction. Exception: the FQN is not used with a GitHub link.
Method names always use empty parentheses: "call bar() to apply." Method names are prefixed with the class/interface name when needed for clarity: Foo.bar().

Extension Points

Extension point name must be followed by "extension point (EP)" for the first occurrence on a page. All following can use "EP" suffix.
Use the FQN when first introducing an extension point (EP) on a page. Rather than stubIndex, introduce com.intellij.stubIndex. Subsequent mentions on the page can be stubIndex.

XML

For XML elements, use the tag notation with syntax highlighting: <idea-version>. Attributes are shown with syntax highlighting, and attribute values are shown in quotes: since-build="191"

Source Code

Source code is represented by using code fences, which are three backticks.

Syntax highlighting is applied by specifying the language after the first set of ticks:

    ```xml
    <tagName attribute="value">XML Text</tagName>
    ```

Supported languages include xml, java, kotlin, groovy, bash, md, php, and text for plaintext.

Whole files can be imported on a page using src attribute after code fences specifying the full path relative to code_samples root folder.

{src="simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFoldingBuilder.java"}

The advantage is the code can come from the code_samples directory, so it will be live code that isn't silently stale.

The disadvantage is the file may contain a large class, too large for the documentation page to be useful. If possible, use include-symbol="ClassName" to show only the class body without any headers and imports. To include only a specific method, specify include-symbol="methodName" additionally.

In any case, please keep code samples concise and avoid any unnecessary "surrounding" code or import statements.

Tables

The syntax is to use the pipe (|) and minus symbols:

    | Column 1 | Column 2 | Column 3 |
    |----------|----------|----------|
    | Blah     | Blah     | Blah     |

Use & #124; (remove space before #!) instead of | to prevent escaping problems for <ui-path> elements inside cells.

Use <p>Line 1</p><p>Line 2</p> for multi-line content in a cell.

Notes and Callouts

Notes and callouts can be specified using the blockquote syntax. The converter looks at the type attribute specified after the text block. If so, it applies a callout style. The example below will be displayed as a callout, styled as a "note":

> This is a simple note.
>
{style="note"}

The styles available for callouts are:

tip—Information that makes the reader more productive (Default).
note—Information that is important for the reader to understand. This callout is reserved for essential points and concepts.
warning—Information that is critical for the user to understand to prevent failures or errors.

Complex callouts can also specify title attribute:

> This is a note.
> We have a lot of text.
> Don't make everyone read it fully by adding a good title.
>
{title="A useful title"}

Images

Every page typically has a dedicated subdirectory within root /images.

Images in this documentation are generally screenshots. For consistency, images should be 296, 460, or 706 pixels wide. The preferred image format is PNG at 144 DPI resolution. A resolution of 72 DPI is acceptable but may look blurry on high-resolution monitors.

Use Window Resizer plugin for exact resizing of the IDE application window.

It is crucial to reduce the size of image files to prevent bloating the repository and impacting the performance of the documentation site. Optimize the image files using a tool such as the PNG optimizer plugin.

Images are embedded in a document by adding a Markdown link to the image like so:

![Alt text](image.png)

If the width of an image needs to be adjusted, it can be specified as follows:

![Alt text](image.png){width="42"}

Images too big to fit into main content can have + overlay control to open a popup with the "zoomed" variant.

For PNG images, provide an additional zoomed variant image.zoomed.png with this notation:

![Alt text](image.png){thumbnail="true"}

For SVG images, use this notation:

![Alt text](image.svg){thumbnail-same-file="true"}

The table of contents for the site is displayed in the tree view on the left side of the site, and it is generated from the ijs.tree file. The list can have nested items, which are displayed as child items in the table of contents.

If absolutely required, overriding the page title text to show in table of contents is possible via toc-title attribute.

Placeholders

If a node does not have its id attribute specified, it will still appear in the table of contents but will be greyed out and not clickable. It acts as a placeholder for a documentation item. A placeholder is useful to keep track of what should be documented, but hasn't yet, and can be helpful to show readers that the topic exists, but isn't yet documented (Pull Requests always welcome!).

Redirects

When renaming pages, redirects must be configured so existing bookmarks continue working. All existing links in other topics must be updated.

Specify the previous path(s) including .html extension in accepts-web-file-names attribute:

<toc-element
        id="themes_getting_started.md"
        accepts-web-file-names="themes.html,themes-intro.html"/>

Last modified: 10 April 2024