/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Free Documentation License
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of this
** file.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \page qdeclarativebasictypes.html
    \title QML Basic Types

    QML has a set of primitive types, as listed below, that are used throughout
    the \l {QML Elements}.

    Some of these types can also be used for defining 
    \c property values in QML. See \l{Writing QML Components: Properties, Methods and Signals} for the
    list of types that can be used for \c property values.

    \annotatedlist qmlbasictypes
*/

/*!
    \qmlbasictype int
    \ingroup qmlbasictypes

    \brief An integer is a whole number, e.g. 0, 10, or -20. 

    An integer is a whole number, e.g. 0, 10, or -20. The possible \c
    int values range from around -2000000000 to around 2000000000,
    although most elements will only accept a reduced range (which they
    mention in their documentation).

    Example:
    \qml
    Item { width: 100; height: 200 }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype bool
    \ingroup qmlbasictypes

    \brief A boolean is a binary true/false value.

    A boolean is a binary true/false value.

    Example:
    \qml
    Item { focus: true; clip: false }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype real
    \ingroup qmlbasictypes

    \brief A real number has a decimal point, e.g. 1.2 or -29.8.

    A real number has a decimal point, e.g. 1.2 or -29.8.

    Example:
    \qml
    Item { width: 100.45; height: 150.82 }
    \endqml

    \note In QML all reals are stored in single precision, \l
    {http://en.wikipedia.org/wiki/IEEE_754} {IEEE floating point}
    format.

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype double
    \ingroup qmlbasictypes

    \brief A double number has a decimal point and is stored in double precision.

    A double number has a decimal point and is stored in double precision, \l
    {http://en.wikipedia.org/wiki/IEEE_754} {IEEE floating point}
    format.

    Example:
    \qml
    Item {
        property double number: 32155.2355
    }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype string
    \ingroup qmlbasictypes

    \brief A string is a free form text in quotes, e.g. "Hello world!".

    A string is a free form text in quotes, e.g. "Hello world!".

    Example:
    \qml
    Text { text: "Hello world!" }
    \endqml

    Strings have a \c length attribute that holds the number of
    characters in the string.

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype url
    \ingroup qmlbasictypes

    \brief A URL is a resource locator, like a file name. 

    A URL is a resource locator, like a file name. It can be either
    absolute, e.g. "http://qt.nokia.com", or relative, e.g.
    "pics/logo.png". A relative URL is resolved relative to the URL of
    the component where the URL is converted from a JavaScript string
    expression to a url property value.

    Example:
    \qml
    Image { source: "pics/logo.png" }
    \endqml

    \raw HTML
    \endraw

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype color
    \ingroup qmlbasictypes

    \brief A color is a standard color name in quotes.

    A color is a standard color name in quotes. It is normally specified
    as an \l {http://www.w3.org/TR/SVG/types.html#ColorKeywords} {SVG
    color name}. These names include colors like "red", "green" and
    "lightsteelblue".

    If the color you want isn't part of this list, colors can also be
    specified in hexidecimal triplets or quads that take the form \c
    "#RRGGBB" and \c "#AARRGGBB" respectively. For example, the color
    red corresponds to a triplet of \c "#FF0000" and a slightly
    transparent blue to a quad of \c "#800000FF".

    Example:
    \qml
    Rectangle { color: "steelblue" }
    Rectangle { color: "transparent" }
    Rectangle { color: "#FF0000" }
    Rectangle { color: "#800000FF" }
    Rectangle { color: "#00000000" }    // ARGB fully transparent
    \endqml

    Or with the \l{QML:Qt::rgba()}{Qt.rgba()}, \l{QML:Qt::hsla()}{Qt.hsla()}, \l{QML:Qt::darker()}{Qt.darker()},
    \l{QML:Qt::lighter()}{Qt.lighter()} or \l{QML:Qt::tint()}{Qt.tint()} functions:

    \qml
    Rectangle { color: Qt.rgba(0.5, 0.5, 0, 1) }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype point
    \ingroup qmlbasictypes

    \brief A point type has x and y attributes.

    A \c point type has \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

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype size
    \ingroup qmlbasictypes
    
    \brief A size type has width and height attributes

    A \c size type has \c width and \c height attributes.

    For example, to read the \l {Image::sourceSize} \c size 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
    LayoutItem { preferredSize: "150x50" }
    \endqml

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

    \qml
    LayoutItem { preferredSize: Qt.size(150, 50) }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype rect
    \ingroup qmlbasictypes

    \brief A rect type has x, y, width and height attributes.

    A \c rect type has \c x, \c y, \c width and \c height attributes.

    For example, to read the \l {Item::childrenRect.x}{Item::childrenRect} \c rect 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

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype date
    \ingroup qmlbasictypes

    \brief A date is specified as "YYYY-MM-DD".

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

    Example:
    \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()}.

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype time
    \ingroup qmlbasictypes

    \brief A time is specified as "hh:mm:ss".

    A time is specified as "hh:mm:ss".

    Example:
    \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()}.

    \sa {QML Basic Types}
 */

/*!
    \qmlbasictype font
    \ingroup qmlbasictypes

    \brief A font type has the properties of a QFont.

    A font type has the properties of a QFont. The properties are:

    \list
    \o \c string font.family
    \o \c bool font.bold
    \o \c bool font.italic
    \o \c bool font.underline
    \o \c real font.pointSize
    \o \c int font.pixelSize
    \endlist

    Example:
    \qml
    Text { font.family: "Helvetica"; font.pointSize: 13; font.bold: true }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype action
    \ingroup qmlbasictypes

    \brief The action type has all the properties of QAction.

    The action type has all the properties of QAction. The properties
    are:

    \list
    \o \c slot action.trigger - invoke the action
    \o \c bool action.enabled - true if the action is enabled
    \o \c string action.text - the text associated with the action
    \endlist

    Actions are used like this:

    \qml
    MouseArea { onClicked: myaction.trigger() }
    State { name: "enabled"; when: myaction.enabled == true }
    Text { text: someaction.text }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype list
    \ingroup qmlbasictypes

    \brief A list of objects.

    A list type contains a list of objects. While not technically
    a basic type, QML supports lists of object types. When used
    from QML, the engine automatically appends each value to the list.
    Items in the list can be accessed by index using the usual
    \c listName[index] syntax.

    For example, the \l Item class contains a list property named
    children that can be used like this:

    \qml
    Item {
        children: [
            Item { id: child1 },
            Rectangle { id: child2; width: 200 },
            Text { id: child3 }
        ]

        Component.onCompleted: {
            console.log("Width of child rectangle:", children[1].width)
        }
    }
    \endqml
    \c child1, \c child2 and \c child3 will be added to the children list
    in the order in which they appear.

    List \l {Adding Properties}{properties} can be created as a
    \c variant type, or as a \c list<Type> type, where \c Type is the
    type of the object in the list:

    \qml
    Item {
        property variant values: [ 10, 20, 'abc', 'xyz' ]

        property list<Rectangle> rects: [
            Rectangle { width: 100; height: 100},
            Rectangle { width: 200; height: 200}
        ]
    }
    \endqml

    A \c variant list can contain values of any of the \l {QML Basic Types}{basic QML types}
    such as numbers, strings, etc. while a \c list<Type> list can only contain values
    that match (or are derived from) the specified \c Type.

    A list property can be cleared by setting it to an empty list:

    \qml
    Item {
        children: []
    }
    \endqml

    A list property cannot be modified in any other way. Items cannot be dynamically added to
    or removed from the list through JavaScript operations; any \c push() operations on the
    list only modify a \e copy of the list and not the actual list. (These current limitations
    are due to restrictions on \l {Property Binding} where lists are involved.)

    You can, however, modify a copy of the list and then reassign the property to the modified
    value. Other options are to create an array object from within a \c .js JavaScript file,
    or implement a custom list element in C++. Here is a QML element that modifies the list in a
    JavaScript file:

    \table
    \row
    \o
    \qml
    // QML
    import "script.js" as Script

    Item {
        Component.onCompleted: {
            Script.addItem('abc')
            console.log("Added:", Script.getList()[0])
        }
    }
    \endqml

    \o
    \code
    // script.js
    var myArray = new Array()

    function getList() {
        return myArray
    }

    function addItem(item) {
        myArray.push(item)
    }
    \endcode
    \endtable

    However, note that a JavaScript list should not be used as a QML \c property value,
    as the property is not updated when the list changes.

    \sa {QML Basic Types}
*/


/*!
    \qmlbasictype variant
    \ingroup qmlbasictypes

    \brief A variant type is a generic property type.

    A variant is a generic property type. A variant type property can hold any of the
    \l {QML Basic Types}{basic type} values:

    \qml
    Item {
        property variant aNumber : 100
        property variant aString : "Hello world!"
        property variant aList : [ 1, 2, "buckle my shoe" ]
    }
    \endqml

    The \c variant type can also hold a \e copy of a JavaScript object. For example, the
    \c animal property below defines a JavaScript object defined with JSON notation. The
    object's properties and values can be examined using the standard JavaScript syntax,
    as shown in the \c Component.onCompleted handler.

    \qml
    Item {
        property variant animal : { 'type': 'bird', 'species': 'galah', 'age': 7 }

        Component.onCompleted: {
            for (var attribute in animal)
                console.log(attribute, "=", animal[attribute])
        }
    }
    \endqml

    It must be noted that the \c animal property holds a \e copy of the defined object, and
    not the object itself. (This is true even if the property refers to an object defined in
    some JavaScript file; the property will hold a copy of the object, and not the actual
    object.) The property essentially holds a copy of the contents within the object. This
    has several implications:

    \list
    \o Changes to any of the property's values (for example, the \c animal.type value
       above) only modify the \e copy of the object, not the object itself. You can, however,
       modify a copy of the object and then reassign the property to the modified value.
    \o Because the property only holds a copy of the object, \l{Property Binding}{bindings} to
       any of the property's individual values are not updated until the whole property is
       reassigned to a new value. For example:

       \qml
       Item {
           property variant animal : { 'type': 'bird', 'species': 'galah', 'age': 7 }

           Text { text: "Animal species: " + animal.species }

           Component.onCompleted: {
               animal.species = 'kookaburra'    // this has no effect on the displayed text

               var newObj = animal
               newObj.species = 'kookaburra'
               animal = newObj  // this will update the displayed text
           }
       }
       \endqml
    \o Since the object values are copied, it does not hold any reference to the original
       object, and extra data such as the object's JavaScript prototype chain is lost in the
       process.
    \endlist

    \sa {QML Basic Types}
*/


/*!
    \qmlbasictype vector3d
    \ingroup qmlbasictypes

    \brief A vector3d type has x, y, and z attributes.

    A \c vector3d type has \c x, \c y, and \c z attributes.

    To create a \c vector3d value, specify it as a "x,y,z" string:

    \qml
    Rotation { angle: 60; axis: "0,1,0" }
    \endqml

    or with the \l{QML:Qt::vector3d()}{Qt.vector3d()} function:

    \qml
    Rotation { angle: 60; axis: Qt.vector3d(0, 1, 0) }
    \endqml

    or as separate \c x, \c y, and \c z components:

    \qml
    Rotation { angle: 60; axis.x: 0; axis.y: 1; axis.z: 0 }
    \endqml

    \sa {QML Basic Types}
*/

/*!
    \qmlbasictype enumeration
    \ingroup qmlbasictypes

    \brief An enumeration type consists of a set of named values.

    An enumeration type consists of a set of named values.

    An enumeration value may be specifed as either a string:
    \qml
    Text { horizontalAlignment: "AlignRight" }
    \endqml
    
    or as \c {<Element>.<value>}:
    \qml
    Text { horizontalAlignment: Text.AlignRight }
    \endqml

    The second form is preferred.

    \sa {QML Basic Types}
*/