QDoc Linking Guidelines

This page is part of the Qt Writing Guidelines

This page contains information about creating links to API pages and other articles and content.

Enabling Linking to Content Outside a Module

To link to a section, API, or page outside of the documentation project (content not included in the .qdocconf file), the module name must be set to the depends qdocconf variable.

depends += qtcore qtqml qtgui qtlinguist

The depends entry corresponds to the directories found in the QT_INSTALL_DOCS directory.

Note: To link to pages outside of the module, consider using the [] syntax as explained in the Resolving Ambiguous or Colliding Link Names section below.

Using QDoc's Autolink Feature

QDoc detects certain keywords such as class names, and attempts to create links to them. But if you have a typo (or the target API is renamed or removed), the link will not work without further warnings. It is therefore not anymore recommended in Qt documentation. Prefer adding links with the explicit \l command instead.

To prevent QDoc from creating a link for a keyword that would otherwise qualify for auto-linking, prefix the keyword with a backslash '\'. To prevent auto-linking for all occurrences of a specific word, add it to the ignorewords configuration variable.

Using the \l Command

In general, to create a link, use the \l command followed by the link name.

\l{Link Name}

Valid link names include:

• Page title
• Page file name (.html)
• Class name
• QML Type name
• Targets created by \target and \keyword
• http://, https://, ftp://, mailto: URLs
• Section titles with the PageTitle#SectionTitle syntax
• API members such as properties and functions with the TypeName::member syntax. For example Button::checked

Notes:

• The parentheses () after QML or C++ functions are required. Do not add parentheses when linking to properties.

For example:

\l{Button::checked} - creates a link to the Button's checked property
\l{Button::clicked()} - creates a link to the Button's clicked() signal

• Typing \l{Button::}{clicked()} is a convenient shortcut for displaying a link to Button::clicked() as clicked().

• The space after the \l is not necessary if it is followed with {} as it adds unnecessary whitespace. Instead of \l {Page}, type either \l{Page} or when there is only one word, \l Page.

Visible Text

Sometimes, to integrate the link name into the sentence or clause, the visible text is necessary.

• The \l{Signals & Slots#Advanced Signals and Slots Usage}{advanced signals and slots example} demonstrates a use for QSignalMapper.

Resolving Ambiguous or Colliding Link Names

To disambiguate links, QDoc allows the author to specify the QDoc project and the type of API using [] after the link command.

For example:

• \l[QML]{EnginioClient} - creates a link to the EnginioClient QML type
• \l[CPP]{EnginioClient} - creates a link to the EnginioClient C++ class
• \l[QtCore]{Qt} - creates a link to the Qt namespace
• \l[QtQml]{Qt} - creates a link to the Qt QML type

Currently only these parameters within [] are recognized:

• QML - for QML types, enumerations, or other definitions in QML modules (specified with )
• CPP - for C++ APIs
• project or module name

Note: The project name is specified in the QDoc configuration file (.qdocconf).

External Pages

To avoid multiple instances of hard-coded HTTP URLs, use the \externalpage command to associate the HTTP URL with a title.

\externalpage https://www.example.com
\title An Example Page

\l{An Example Page} creates link to http://www.example.com. There is a set of external pages in qtbase/doc/global/externalsites directory. The command can be declared in the module documentation directory if it is not used anywhere else in Qt to avoid being unnecessarily included in other modules' index files.

Various Guidelines

• It is best if the link title and visible text are in the same line so that they are more readable and easily searched.
• Be mindful about colliding titles by avoiding certain keywords or by creating descriptive page titles.
• Linking directly to the HTML filename should be used as a last resort because the filename can change.