Developer portal generation guide

MRTK uses docfx to generate html documentation out of triple slash comments in code and .md files in the MRTK repository. Docfx documentation generation is automatically triggered by CI on completed PRs in the mrtk_development branch. The current state of the developer documentation can be found on the MRTK github.io page

Docfx supports DFM Docfx Flavored Markdown which includes GFM Github Flavored Markdown. The full documentation and feature list can be found here

Docfx is not only converting but also checking all used local links in the documentation. If a path can't be resolved it won't be converted into its html equivalent. Therefor it's important to only use relative paths when referring to other local files.

Building docfx locally

The docfx build files in the MRTK repo can be used to create a local version of the developer documentation in a doc/ subfolder in the root of the project.

Setup

get the latest version of docfx
extract the files in a folder on your computer
add the folder to your PATH in your environment variables

Generation

open a powershell or cmd prompt in the root of the MRTK project
execute docfx docfx.json (optionally with the -f option to force a rebuild of doc files)
execute docfx serve doc (optionally with -p portnumber if you don't want to use the 8888 default port)
open a web browser with localhost:portnumber

Note that on executing the docfx command on the json build file docfx will show any broken links in the documentation as warning. Please make sure whenever you perform changes on any of the documentation files or API to update all links pointing to these articles or code.

Verifying docfx on github

Whenever a PR includes a change that might affect documentation CI has to be executed to run a check on docfx for broken links. This can be triggered by posting the command /azp run mrtk_docs into the PR if the user has sufficient rights to do so. The command will trigger a CI job which will add a docs build to the checks section of the PR.

Using crefs and hrefs in /// documented code

Docfx supports crefs in /// documented code. It will translate those references to links pointing to the generated api documentation or to external documentation websites. External xref services for resolving links to external libraries/apis can be added to the docfx.json build settings file in the property xrefService.

For external apis that don't provide an xref service hrefs to the documentation website can be added to the comments.

Examples:

/// Links to MRTK internal class SystemType
/// <see cref="Microsoft.MixedReality.Toolkit.Utilities.SystemType"/>

/// Links to external API - link provided by xref service
/// <see cref="System.Collections.Generic.ICollection{Type}.Contains"/>

/// Links to Unity web API reference
/// <see href="https://docs.unity3d.com/ScriptReference/EditorGUI.PropertyField.html">EditorGUI.PropertyField</see>

Linking in .md documentation files

Docfx is translating and validating all relative local links on generation, there's no special syntax required. Referring to another documentation article should always be done by referring to the corresponding .md file, never the auto generated .html file. Please note that all links to local files need to be relative to the file you're modifying.

Linking to the API documentation can be done by using cross references. Docfx automatically generated UIDs for all API docs by mangling the signature.

Example:

This links to the BoundarySystem API as well as this short version: Microsoft.MixedReality.Toolkit.Boundary

This links to the [BoundarySystem API](xref:Microsoft.MixedReality.Toolkit.Boundary)
as well as this short version: @Microsoft.MixedReality.Toolkit.Boundary

Enumerating available xrefs

Xref syntax can be difficult to remember - it's possible to enumerate all of the available xref IDs by first running docfx locally:

docfx docfx.json

This will generate an xrefmap.yml file, which will be located in docs/xrefmap.yml.

For example, in order to link the following overload of HandleEvent, the syntax is fairly arcane:

- uid: Microsoft.MixedReality.Toolkit.BaseEventSystem.HandleEvent``1(BaseEventData,ExecuteEvents.EventFunction{``0})
  name: HandleEvent<T>(BaseEventData, ExecuteEvents.EventFunction<T>)
  href: api/Microsoft.MixedReality.Toolkit.BaseEventSystem.html#Microsoft_MixedReality_Toolkit_BaseEventSystem_HandleEvent__1_BaseEventData_ExecuteEvents_EventFunction___0__
  commentId: M:Microsoft.MixedReality.Toolkit.BaseEventSystem.HandleEvent``1(BaseEventData,ExecuteEvents.EventFunction{``0})
  name.vb: HandleEvent(Of T)(BaseEventData, ExecuteEvents.EventFunction(Of T))
  fullName: Microsoft.MixedReality.Toolkit.BaseEventSystem.HandleEvent<T>(BaseEventData, ExecuteEvents.EventFunction<T>)
  fullName.vb: Microsoft.MixedReality.Toolkit.BaseEventSystem.HandleEvent(Of T)(BaseEventData, ExecuteEvents.EventFunction(Of T))
  nameWithType: BaseEventSystem.HandleEvent<T>(BaseEventData, ExecuteEvents.EventFunction<T>)
  nameWithType.vb: BaseEventSystem.HandleEvent(Of T)(BaseEventData, ExecuteEvents.EventFunction(Of T))

It's easy, however, to search for the name and then use the entire uid field as the xref.

In this example, the xref would look like: (xref:Microsoft.MixedReality.Toolkit.BaseEventSystem.HandleEvent1(BaseEventData,ExecuteEvents.EventFunction{0}))

Adding new .md files to developer docs

Docfx will pick up any .md files in folders that are added as content files in the build section of the docfx.json and generate html files out of them. For new folders a corresponding entry in the build file needs to be added.

To determine the entries of the navigation in the developer docs docfx uses toc.yml/toc.md - table of content files. The toc file in the root of the project defines entries in the top navigation bar whereas the toc.yml files in the subfolders of the repo define subtopics in the sidebar navigation. toc.yml files can be used for structuring and there can be any amount of those files. For more info about defining entries for toc.yml check the docfx documentation entry on toc.

Resource files

There are some files like images, videos or PDFs that the documentation can refer to but are not converted by docfx. For those files there's a resource section in the docfx.json. Files in that section will only be copied over without performing any conversion on them.

Currently there's a definition for the following resource types:

ResourceType	Path
Images	Documentation/Images/

Releasing a new version

Multiple versions of developer docs are supported and can be switched by the version drop down in the top menu bar. If you're releasing a new version perform the following steps to have your version on the developer docs page.

Optional: Adjusting your docfx.json
Depending on whether you want to have the "Improve this doc" to point to a specific version of the github repo you will have to add the following entry to the globalMetaData section in the docfx.json file before calling the docfx command:
```
"_gitContribute": {
    "repo": "https://github.com/Microsoft/MixedRealityToolkit-Unity.git",
    "branch": "mrtk_development"
}
```
If you don't set this up docfx will default to the branch and repo of the current folder you're calling docfx from.
Create your docfx docs by calling docfx docfx.json in the root of the repo
Create a folder with the name of your version in the version folder of the gh-pages branch and copy the contents of the generated doc folder into that folder
Add your version number into the versionArray in web/version.js
Push the modified version.js to mrtk_development branch and the changes in gh-pages branch

CI will pick up the changes done to the version.js file and update the version dropdown automatically.

Supporting development branches on CI

The versioning system can also be used for showing doc versions from other dev branches that are built by CI. When setting up CI for one of those branches make sure your powershell script on CI copies the contents of the generated docfx output into a version folder named after your branch and add the corresponding version entry into the web/version.js file.

Good practices for developers

Use relative paths whenever referring to MRTK internal pages
Use cross references for linking to any MRTK API page by using the mangled UID
Use crefs and hrefs to link to internal or external documentation in /// comments
Use the indicated folders in this doc for resource files
Run docfx locally and check for warnings in the output whenever you modify existing APIs or update documentation pages
Watch out for docfx warnings on CI after completing and merging your PR into one of the official MRTK branches

Common errors when generating docs

toc.yml errors: usually happens when an .md file gets moved/renamed or removed but the table of content file (toc.yml) pointing to that file wasn't updated accordingly. On the website this will result in a broken link on our top level or side navigation
/// comments errors
- xml tag errors - docfx like any other xml parser can't handle malformed xml tags.
- typos in crefs
- incomplete namespace identifiers - docfx won't need the full namespace to the symbol you're referring to but the relative part of the namespace that's not included in the surrounding namespace of the cref.
  - Example: if you're in a namespace Microsoft.MixedReality.Toolkit.Core.Providers.UnityInput and the file you want to link in is Microsoft.MixedReality.Toolkit.Core.Interfaces.IMixedRealityServiceRegistrar your cref can look like this: cref="Interfaces.IMixedRealityServiceRegistrar"
- External crefs - As long as there's no xref service available (and listed in the docfx build file) crefs to external libraries won't work. If you still want to link to a specific external symbol that doesn't have xref service but an online api documentation you can use a href instead. Example: linking to EditorPrefs of Unity: <see href="https://docs.unity3d.com/ScriptReference/EditorPrefs.html">EditorPrefs</see>

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