path: root/src/qml/doc/src/qmltypereference.qdoc

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/*!
\qmlmodule QtQml 2
\title Qt QML QML Types
\ingroup qmlmodules
\brief List of QML types provided by the Qt QML module

The \c QtQml module provides the definition and implementation of various
convenience types which can be used with the QML language, including some
elementary QML types which can provide the basis for further extensions to the
QML language.

The \c QtQml module provides the \c QtObject and \c Component object types
which may be used in QML documents.  These types are non-visual and provide
building-blocks for extensions to QML.

\section1 Importing QtQml

The types provided by the \c QtQml module are only available in a QML document
if that document imports the \c QtQml namespace (or if the document imports the
\c QtQuick namespace, as noted below).

The current version of the \c QtQml module is version 2.0, and thus it may be
imported via the following statement:

\qml
import QtQml 2.0
\endqml

Most clients will never need to use the \c QtQml import, as all of the types
and functionality provided by the \c QtQml namespace are also provided by the
\c QtQuick namespace which may be imported as follows:

\qml
import QtQuick 2.0
\endqml

See the \l{Qt Quick} module documentation for more information about the
\c QtQuick namespace and what it provides to QML application developers.

The documentation for the types below applies equally to the types of the same
name provided by the \l{Qt Quick} module, as they are in fact identical.

\section1 Basic Types

The following \l{qtqml-typesystem-basictypes.html}{QML basic types} are
provided:

\annotatedlist qtqmlbasictypes

\section1 Object Types

The following \l{qtqml-typesystem-objecttypes.html}{QML object types} are
provided:

\section2 QtObject

The \c QtObject type provides a basic instantiable object which can be used in
QML applications.  It is non-visual, but may have properties, methods, signals
and signal handlers.

For example, the following QtObject has several properties, one of which has
been assigned a \l{Property Binding}
{binding}, and a \l{Signal and Handler Event System}{signal handler} for
the default change signal which exists for one of its properties:

\code
    import QtQuick 2.0

    QtObject {
        property int a: 15
        property int b: a + 22
        property int changeCount: 0

        onAChanged: {
            changeCount += 1;
        }
    }
\endcode

\section2 Component

The \c Component type provides a basic re-usable component which allows
instances of another type to be instantiated on-demand.  It may be given an
\c id and it has a default property which is the object type to instantiate,
but no other properties may be added to it.

For example, the following QtObject has two different \l Component
properties, and it uses those components to dynamically construct objects at
run-time:

\code
    import QtQuick 2.0

    QtObject {
        id: root
        property bool which: true

        property Component a: Component {
            id: firstComponent
            QtObject {
                property int answer: 42
                function activate() {
                    console.log("The answer is: " + answer);
                }
            }
        }

        property Component b: Component {
            id: secondComponent
            QtObject {
                property string message: "Hello, World!"
                function activate() {
                    console.log(message);
                }
            }
        }

        function activateDynamicObject() {
            var o = {};
            if (which) {
                which = false;
                o = a.createObject(null); // no parent
            } else {
                which = true;
                o = b.createObject(null); // no parent
            }
            o.activate();
        }
    }
\endcode
*/

/*!
\qmlbasictype date
\ingroup qtqmlbasictypes
\ingroup qtquickbasictypes
\brief a date value.

The \c date type refers to a date value.

To create a \c date value, specify it as a "YYYY-MM-DD" string:

\qml
MyDatePicker { minDate: "2000-01-01"; maxDate: "2020-12-31" }
\endqml

To read a date value returned from a C++ extension class, use
\l{QML:Qt::formatDate()}{Qt.formatDate()} and \l{QML:Qt::formatDateTime()}{Qt.formatDateTime()}.

When integrating with C++, note that any QDate value
\l{qtqml-cppintegration-data.html}{passed into QML from C++} is automatically
converted into a \c date value, and vice-versa.

Note that the date type has comparison semantics which match
those of the JavaScript Date object.  To compare the value
of two date properties, you should compare their "toString()"
values.

This basic type is provided by the QML language.

\sa {QML Basic Types}
*/

/*!
\qmlbasictype time
\ingroup qtqmlbasictypes
\ingroup qtquickbasictypes
\brief a time value.

The \c time type refers to a time value.

To create a \c time value, specified as "hh:mm:ss":

\qml
MyTimePicker { time: "14:22:15" }
\endqml

To read a time value returned from a C++ extension class, use
\l{QML:Qt::formatTime()}{Qt.formatTime()} and \l{QML:Qt::formatDateTime()}{Qt.formatDateTime()}.

Note that when converting historical times to and from javascript that QDateTime and the JS Date object
have different methods of calculating historical daylight savings time application. This can lead to variations of one hour
when converting to historical local time.

When integrating with C++, note that any QTime value
\l{qtqml-cppintegration-data.html}{passed into QML from C++} is automatically
converted into a \c time value, and vice-versa.

This basic type is provided by the QML language.

\sa {QML Basic Types}
*/

/*!
\qmlbasictype point
\ingroup qtqmlbasictypes
\ingroup qtquickbasictypes
\brief a value with x and y attributes.

The \c point type refers to a value with \c x and \c y attributes.

To create a \c point value, specify it as a "x,y" string:

\qml
CustomObject { myPointProperty: "0,20" }
\endqml

Or use the \l{QML:Qt::point()}{Qt.point()} function:

\qml
CustomObject { myPointProperty: Qt.point(0, 20) }
\endqml

When integrating with C++, note that any QPoint or QPointF value
\l{qtqml-cppintegration-data.html}{passed into QML from C++} is automatically
converted into a \c point value. When a \c point value is passed to C++, it
is automatically converted into a QPointF value.

\sa{QML Basic Types}
*/

/*!
\qmlbasictype size
\ingroup qtqmlbasictypes
\ingroup qtquickbasictypes
\brief a value with width and height attributes

The \c size type refers to a value with has \c width and \c height attributes.

For example, to read the \c width and \c height values of the
\l {Image::sourceSize} size-type property:

\qml
Column {
    Image { id: image; source: "logo.png" }
    Text { text: image.sourceSize.width + "," + image.sourceSize.height }
}
\endqml

To create a \c size value, specify it as a "width x height" string:

\qml
Image { sourceSize: "150x50" }
\endqml

Or use the \l{QML:Qt::size()}{Qt.size()} function:

\qml
Image { sourceSize: Qt.size(150, 50) }
\endqml

When integrating with C++, note that any QSize or QSizeF value
\l{qtqml-cppintegration-data.html}{passed into QML from C++} is automatically
converted into a \c size value, and vice-versa. When a \c size value is passed to C++, it
is automatically converted into a QSizeF value.

\sa{QML Basic Types}
*/

/*!
\qmlbasictype rect
\ingroup qtqmlbasictypes
\ingroup qtquickbasictypes
\brief a value with x, y, width and height attributes.

The \c rect type refers to a value with \c x, \c y, \c width and \c height attributes.

For example, to read the \c width and \c height values of the \l Item
\l {Item::childrenRect.x}{childrenRect} rect-type type property:

\qml
Rectangle {
    width: childrenRect.width
    height: childrenRect.height

    Rectangle { width: 100; height: 100 }
}
\endqml

To create a \c rect value, specify it as a "x, y, width x height" string:

\qml
CustomObject { myRectProperty: "50,50,100x100" }
\endqml

Or use the \l{QML:Qt::rect()}{Qt.rect()} function:

\qml
CustomObject { myRectProperty: Qt.rect(50, 50, 100, 100) }
\endqml

When integrating with C++, note that any QRect or QRectF value
\l{qtqml-cppintegration-data.html}{passed into QML from C++} is automatically
converted into a \c rect value, and vice-versa. When a \c rect value is passed to C++, it
is automatically converted into a QRectF value.

\sa{QML Basic Types}
*/