Create new documentation structure

The documentation currently has no clear separation between Qt QML
and Qt Quick.  With recent commits like:
6c8378eaf1edbbefe6aaa3672b0127816a004fd7
and
ab1e510121c8a679fdaca12ccd30e0f7ac12a26b
the separation between the language definition and implementation,
provided by Qt QML, and the standard library for the QML language,
provided by Qt Quick, is clear.

This commit creates a new documentation structure that is more
navigable and separates concepts into logical categories, with
clear separation between QtQML and QtQuick.  It also provides a more
generic QML Application Developer Resources page which contains links
to information for QML application developers.

Change-Id: Ia807ccfbfd24ffa0e1c7f0a51ed9d2ed3aa6a733
Reviewed-by: Martin Jones <martin.jones@nokia.com>

1 files changed, 690 insertions, 0 deletions

diff --git a/src/qml/doc/src/typesystem/basictypes.qdoc b/src/qml/doc/src/typesystem/basictypes.qdoc
new file mode 100644
index 0000000000..3c1b849b5b
--- /dev/null
+++ b/src/qml/doc/src/typesystem/basictypes.qdoc
@@ -0,0 +1,690 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms
+** and conditions contained in a signed written agreement between you
+** and Nokia.
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+/*!
+\page qtqml-basictypes.html
+\title QML Basic Types
+\brief Description of basic types provided by the Qt QML module
+
+
+A \e{basic type} is one that refers to a simple value, as opposed to a QML object with properties, signals, methods and so on.
+
+Basic types can be used to refer to:
+
+\list
+\li A single value (e.g. \l int refers to a single number, \l var can refer to a single list of items)
+\li A value that contains a simple set of property-value pairs (e.g. \l size refers to a value with \c width and \c height attributes)
+\endlist
+
+Unlike a QML type, a basic type cannot be used for QML object definitions. It is not possible, for example, to declare an \c int{} object or a \c size{} object.
+
+See \l {QML Basic Types} for the list of basic types that are supported by the QML engine. Basic types are supported by the engine by default and do not require an \l {Import Statements}{Import Statements} to be used, unlike QML types.
+
+
+
+    \annotatedlist qmlbasictypes
+
+    To create additional types, such as data types created in C++, read the
+    \l{Defining QML Object Types from C++} article.
+*/
+
+/*!
+    \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
+
+    \b{Note:} In QML all reals are stored in double 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
+
+    Note that as QML requires URL paths, you should use "qrc:///" instead of ":/" for
+    referring to files stored with the \l {Qt Resource System}.
+    Usually you will only have to do this once, because relative URLs resolved from
+    that file will use the same protocol.
+
+    \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:
+    \div{float-right}
+    \inlineimage declarative-colors.png
+    \enddiv
+
+    \snippet qml/colors.qml colors
+
+    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()}.
+
+    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.
+
+    \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
+    \li \c string font.family
+    \li \c bool font.bold
+    \li \c bool font.italic
+    \li \c bool font.underline
+    \li \c real font.pointSize
+    \li \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
+    \li \c slot action.trigger - invoke the action
+    \li \c bool action.enabled - true if the action is enabled
+    \li \c string action.text - the text associated with the action
+    \endlist
+
+    Actions are used like this:
+
+    \qml
+    Item {
+        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 {Property Binding}{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 list<Rectangle> rects: [
+            Rectangle { width: 100; height: 100},
+            Rectangle { width: 200; height: 200}
+        ]
+    }
+    \endqml
+
+    A list property can only contain values that match (or are derived from) the
+    specified \c Type.
+
+    While the \c rects property can be reassigned to a different list value (including
+    an empty list), its individual values cannot be modified. See the \l variant type
+    documentation for details.
+
+    \sa {QML Basic Types}
+*/
+
+ /*!
+    \qmlbasictype var
+    \ingroup qmlbasictypes
+
+    \brief A var type is a generic property type.
+
+    A var is a generic property type capable of storing any data type.
+    It is equivalent to a regular JavaScript variable.
+    For example, var properties can store numbers, strings, objects,
+    arrays and functions:
+
+    \qml
+    Item {
+        property var aNumber: 100
+        property var aBool: false
+        property var aString: "Hello world!"
+        property var anotherString: String("#FF008800")
+        property var aColor: Qt.rgba(0.2, 0.3, 0.4, 0.5)
+        property var aRect: Qt.rect(10, 10, 10, 10)
+        property var aPoint: Qt.point(10, 10)
+        property var aSize: Qt.size(10, 10)
+        property var aVector3d: Qt.vector3d(100, 100, 100)
+        property var anArray: [1, 2, 3, "four", "five", (function() { return "six"; })]
+        property var anObject: { "foo": 10, "bar": 20 }
+        property var aFunction: (function() { return "one"; })
+    }
+    \endqml
+
+    It is important to note that changes in regular properties of JavaScript
+    objects assigned to a var property will \b{not} trigger updates of bindings
+    that access them.  The example below will display "The car has 4 wheels" as
+    the change to the wheels property will not cause the reevaluation of the
+    binding assigned to the "text" property:
+
+    \qml
+    Item {
+        property var car: new Object({wheels: 4})
+
+        Text {
+            text: "The car has " + car.wheels + " wheels";
+        }
+
+        Component.onCompleted: {
+            car.wheels = 6;
+        }
+    }
+    \endqml
+
+    If the onCompleted handler instead had \tt{"car = new Object({wheels: 6})"}
+    then the text would be updated to say "The car has 6 wheels"., since the
+    car property itself would be changed, which causes a change notification
+    to be emitted.
+
+    A \c var type property can also hold an image or pixmap.
+    A \c var which contains a QPixmap or QImage is known as a
+    "scarce resource" and the declarative engine will attempt to
+    automatically release such resources after evaluation of any JavaScript
+    expression which requires one to be copied has completed.
+
+    Clients may explicitly release such a scarce resource by calling the
+    "destroy" method on the \c var property from within JavaScript.  They
+    may also explicitly preserve the scarce resource by calling the
+    "preserve" method on the \c var property from within JavaScript.
+    For more information regarding the usage of a scarce resource, please
+    see \l{Scarce Resources in JavaScript}.
+
+    \sa {QML Basic Types}
+*/
+
+
+/*!
+    \obsolete
+    \qmlbasictype variant
+    \ingroup qmlbasictypes
+
+    \brief A variant type is a generic property type.
+
+    A variant is a generic property type. It is obsolete and exists only to
+    support old applications; new applications should use "var" type
+    properties instead.
+
+    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 aBool: false
+    }
+    \endqml
+
+    A \c variant type property can also hold an image or pixmap.
+    A \c variant which contains a QPixmap or QImage is known as a
+    "scarce resource" and the declarative engine will attempt to
+    automatically release such resources after evaluation of any JavaScript
+    expression which requires one to be copied has completed.
+
+    Clients may explicitly release such a scarce resource by calling the
+    "destroy" method on the \c variant property from within JavaScript.  They
+    may also explicitly preserve the scarce resource by calling the
+    "preserve" method on the \c variant property from within JavaScript.
+    For more information regarding the usage of a scarce resource, please
+    see \l{Scarce Resources in JavaScript}.
+
+    Finally, the \c variant type can also hold:
+
+    \list
+    \li An array of \l {QML Basic Types}{basic type} values
+    \li A map of key-value pairs with \l {QML Basic Types}{basic-type} values
+    \endlist
+
+    For example, below is an \c items array and an \c attributes map. Their
+    contents can be examined using JavaScript \c for loops. Individual array
+    values are accessible by index, and individual map values are accessible
+    by key:
+
+    \qml
+    Item {
+        property variant items: [1, 2, 3, "four", "five"]
+        property variant attributes: { 'color': 'red', 'width': 100 }
+
+        Component.onCompleted: {
+            for (var i=0; i<items.length; i++)
+                console.log(items[i])
+
+            for (var prop in attributes)
+                console.log(prop, "=", attributes[prop])
+        }
+    }
+    \endqml
+
+    While this is a convenient way to store array and map-type values, you
+    must be aware that the \c items and \c attributes properties above are \e not
+    QML objects (and certainly not JavaScript object either) and the key-value
+    pairs in \c attributes are \e not QML properties. Rather, the \c items
+    property holds an array of values, and \c attributes holds a set of key-value
+    pairs. Since they are stored as a set of values, instead of as an object,
+    their contents \e cannot be modified individually:
+
+    \qml
+    Item {
+        property variant items: [1, 2, 3, "four", "five"]
+        property variant attributes: { 'color': 'red', 'width': 100 }
+
+        Component.onCompleted: {
+            items[0] = 10
+            console.log(items[0])     // This will still be '1'!
+            attributes.color = 'blue'
+            console.log(attributes.color)     // This will still be 'red'!
+        }
+    }
+    \endqml
+
+    Additionally, since \c items and \c attributes are not QML objects, changing
+    their individual values do not trigger property change notifications. If
+    the above example had \c onNumberChanged or \c onAnimalChanged signal
+    handlers, they would not have been called.  If, however, the \c items or
+    \c attributes properties themselves were reassigned to different values, then
+    such handlers would be called.
+
+    One way to "update" the contents of an array or map is to copy the property
+    to a JavaScript object, modify the copy as desired, and then reassign the
+    property to the updated copy. Note, however, that this is not efficient.
+    In the example below, which reassigns the \c attributes property, the \e entire
+    set of key-value pairs must be serialized and deserialized every time it is
+    copied between a JavaScript object and a QML property:
+
+    \qml
+    Item {
+        property variant attributes: { 'color': 'red', 'width': 100 }
+
+        Component.onCompleted: {
+            // Change the value of attributes.color to 'blue':
+            var temp = attributes     // copy all values to 'temp'
+            temp.color = 'blue'
+            attributes = temp         // copy all values back to 'attributes'
+        }
+    }
+    \endqml
+
+    Since this operation is inefficient, if a list or map should be modifiable,
+    it is better to use alternative approaches. For example, you could implement
+    a custom C++ list element, or write to a JavaScript object defined from
+    within a JavaScript file.
+
+    JavaScript programmers should also note that when a JavaScript object is
+    copied to an array or map property, the \e contents of the object (that is,
+    its key-value properties) are copied, rather than the object itself. The
+    property does not hold a reference to the original JavaScript object, and
+    extra data such as the object's JavaScript prototype chain is also lost in
+    the process.
+
+    \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 specified 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}
+*/