// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
\page qtwritingstyle-qml.html
\title QML Documentation Style
\brief Style guidelines for QML documentation

QDoc can process QML types defined as C++ classes and QML types defined in
\c .qml files. For C++ classes documented as QML types, the QDoc comments are
in the \c .cpp file while QML types defined in QML are in the \c .qml
file. The C++ classes must also be documented
documented with the QML \l{topic-commands}{topic commands}:

\list
\li \l{qmlattachedproperty-command}{\\qmlattachedproperty}
\li \l{qmlattachedsignal-command}{\\qmlattachedsignal}
\li \l{qmlvaluetype-command}{\\qmlvaluetype}
\li \l{qmltype-command}{\\qmltype}
\li \l{qmlmethod-command}{\\qmlmethod}
\li \l{qmlproperty-command}{\\qmlproperty}
\li \l{qmlsignal-command}{\\qmlsignal}
\li \l{qmlmodule-command}{\\qmlmodule}
\li \l{inqmlmodule-command}{\\inqmlmodule}
\li \l{nativetype-command}{\\nativetype}
\endlist

For QML types defined in \c .qml files, QDoc will parse the QML and determine
the properties, signals, and the type within the QML definition. The QDoc
block then needs to be immediately above the declaration. For QML types
implemented in C++, QDoc will output warnings if the C++ class documentation
does not exist. The class documentation may be marked as
\l{internal-command}{internal} if it is not a public API.

\section1 QML Types

The \l{qmltype-command}{\\qmltype} command is for QML type documentation.

\snippet examples/qml.qdoc.sample qmltype

The \l{nativetype-command}{\\nativetype} command accepts the C++ class which
implements the QML type as the argument. For types implemented in QML, this
is not needed.

The \e{brief description} provides a summary for the QML type. The brief does
not need to be a complete sentence and may start with a verb. QDoc will append
the brief description onto the QML type in tables and generated lists.

\code
\qmltype ColorAnimation
\brief Animates changes in color values
\endcode

Here are some alternate verbs for the brief statement:
\list
\li "Provides..."
\li "Specifies..."
\li "Describes..."
\endlist

The \e{detailed description} follows the brief and may contain images, snippet,
and link to other documentation.

\section1 Properties

The property description focuses on what the property \e does and may use the
following style:

Property documentation usually starts with "This property..." but for certain
properties, these are the common expressions:
\list
\li "This property holds..."
\li "This property describes..."
\li "This property represents..."
\li "Returns \c true when... and \c false when..." - for properties that
are marked \c{read-only}.
\li "Sets the..." - for properties that configure a type.
\endlist

\section1 Signals and Handlers Documentation

QML signals are documented either in the QML file or in the C++ implementation
with the \l{qmlsignal-command}{\\qmlsignal} command. Signal documentation
must include the condition for emitting the signal, mention the corresponding
signal handler, and document whether the signal accepts a parameter.

\snippet examples/qml.qdoc.sample signals

These are the possible documentation styles for signals:
\list
\li "This signal is triggered when..."
\li "Triggered when..."
\li "Emitted when..."
\endlist

\section1 Methods and QML Functions

Typically, function documentation immediately precedes the implementation of the
function in the \c .cpp file. The \l{topic-commands}{topic command} for
functions is \l{fn-command}{\\fn}. For functions in QML, the
documentation must reside immediately above the function declaration.

The function documentation starts with a verb, indicating the operation the
function performs.

\snippet examples/qml.qdoc.sample function

Some common verbs for function documentation:
\list
\li "Copies..." - for constructors
\li "Destroys..." - for destructors
\li "Returns..." - for accessor functions
\endlist

The function documentation must document:
\list
\li the return type
\li the parameters
\li the actions of the functions
\endlist

The \l{a-command}{\\a} command marks the parameter in the documentation.
The return type documentation should link to the type documentation or be
marked with the \l{c-command}{\\c} command in the case of boolean values.

\section1 Enumerations

QML enumerations are documented as QML properties with the
\l{qmlproperty-command}{\\qmlproperty} command. The type of the property
is \c enumeration. Use the \l{value-command}{\\value} command to document
the enum values. Add the type name as a prefix to each value, separated by
a period (.), as QDoc does not do this automatically.

\snippet examples/qml.qdoc.sample enums

The QDoc comment lists the values of the enumeration.

If the enumeration is implemented in C++, consider using the
\l{qmlenumeratorsfrom-command}{\\qmlenumeratorsfrom} command.
If this isn't possible, the documentation may also directly link to the
corresponding C++ enumeration. However, the QDoc comment should then advise that
the enumeration is a C++ enumeration.
*/

