Qt 5.9 | QDoc Manual | QML Documentation Style

Qt 5.9.9 Reference Documentation

# QML Documentation Style

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

- \qmlattachedproperty
- \qmlattachedsignal
- \qmlbasictype
- \qmltype
- \qmlmethod
- \qmlproperty
- \qmlsignal
- \qmlmodule
- \inqmlmodule
- \instantiates

For QML types defined in `.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 internal if it is not a public API.

## QML Types

The \qmltype command is for QML type documentation.

          \qmltype TextEdit
          \instantiates QQuickTextEdit
          \inqmlmodule QtQuick
          \ingroup qtquick-visual
          \ingroup qtquick-input
          \inherits Item
          \brief Displays multiple lines of editable formatted text

          The TextEdit item displays a block of editable, formatted text.

          It can display both plain and rich text. For example:

          \qml
              TextEdit {
                  width: 240
                  text: "<b>Hello</b> <i>World!</i>"
                  font.family: "Helvetica"
                  font.pointSize: 20
                  color: "blue"
                  focus: true
              }
          \endqml

          \image declarative-textedit.gif

          ... omitted detailed description

          \sa Text, TextInput, {examples/quick/text/textselection}{Text Selection example}

The \instantiates accepts the C++ class which implements the QML type as the argument. For types implemented in QML, this is not needed.

The 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.

      \qmltype ColorAnimation
      \brief Animates changes in color values

Here are some alternate verbs for the brief statement:

- "Provides..."
- "Specifies..."
- "Describes..."

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

## Properties

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

Property documentation usually starts with "This property..." but for certain properties, these are the common expressions:

- "This property holds..."
- "This property describes..."
- "This property represents..."
- "Returns `true` when... and `false` when..." - for properties that are marked `read-only`.
- "Sets the..." - for properties that configure a type.

## Signals and Handlers Documentation

QML signals are documented either in the QML file or in the C++ implementation with the \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.

      /*
          This signal is emitted when the user clicks the button. A click is defined
          as a press followed by a release. The corresponding handler is
          \c onClicked.
      */
      signal clicked()

These are the possible documentation styles for signals:

- "This signal is triggered when..."
- "Triggered when..."
- "Emitted when..."

## Methods and JavaScript Functions

Typically, function documentation immediately precedes the implementation of the function in the `.cpp` file. The topic command for functions is \fn. For functions in QML or JavaScript, the documentation must reside immediately above the function declaration.

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

      /*
          \qmlmethod QtQuick2::ListModel::remove(int index, int count = 1)

          Deletes the content at \a index from the model.

          \sa clear()
      */
      void QQuickListModel::remove(QQmlV8Function *args)

Some common verbs for function documentation:

- "Copies..." - for constructors
- "Destroys..." - for destructors
- "Returns..." - for accessor functions

The function documentation must document:

- the return type
- the parameters
- the actions of the functions

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

## Enumerations

QML enumerations are documented as QML properties with the \qmlproperty command. The type of the property is `enumeration`.

      /*!
      \qmlproperty enumeration QtQuick2::Text::font.weight

      Sets the font's weight.

      The weight can be one of:
      \list
      \li Font.Light
      \li Font.Normal - the default
      \li Font.DemiBold
      \li Font.Bold
      \li Font.Black
      \endlist
      */

The QDoc comment lists the values of the enumeration. If the enumeration is implemented in C++, the documentation may link to the corresponding C++ enumeration. However, the QDoc comment should advise that the enumeration is a C++ enumeration.