+++ /dev/null
-/****************************************************************************
-**
-** 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.
-**
-**
-**
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
-\title Qt Quick
-\page qtquick-reference.html
-\inqmlmodule QtQuick 2
-\ingroup qt-gui-concepts
-\ingroup overviews
-
-\brief Qt Quick provides a declarative framework for building highly
-dynamic applications.
-
-For App Developers and Designers, who want to deliver apps with amazing user
-experience, Qt provides the QML language, the Qt Quick Elements, and tools in Qt
-Creator that make it faster than ever to transform your brilliant idea into a
-winning App across mobile, embedded, and desktop platforms.
-
-\target qtquick-overviews
-\div {class="threecolumn_area"}
- \div {class="heading"}
- QML Topics
- \enddiv
- QML is a declarative language for creating flexible and reusable
- components. The QML runtime powers QML based applications. The runtime
- includes a QML engine, JavaScript engine, and mechanism to bind to the Qt
- Framework.
-
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- QML Essentials
- \enddiv
- \list
- \li \l{QML Components}{Components}
- \li \l{Properties and Property Binding in QML}{Properties and Property Binding}
- \li \l{JavaScript Expressions in QML}{JavaScript Code}
- \li \l{QML Signal and Handler Event System}{Signal and Handler Event System}
- \li \l{QML Modules}{Modules}
- \endlist
- \list
- \li \l{What's New in Qt Quick 2}{What's New in Qt Quick}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- QML Engine
- \enddiv
- \list
- \li \l{The QML Engine}
- \li \l{QML Global Object}
- \li \l{Dynamic Object Management in QML}{Dynamic Object Management}
- \li \l{QML Performance}{Performance}
- \endlist
- \enddiv
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- Reference
- \enddiv
- \list
- \li \l{QML Syntax}
- \li \l{QML Basic Types}{Data Types}
- \li \l{QML Coding Conventions}{Coding Conventions}
- \li \l{QML Security}{Security Model}
- \li \l{QML Scope}{Scope Model}
- \li \l{QML Documents}{Documents}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- QML Bindings with Qt C++
- \enddiv
- \list
- \li \l{Creating QML Types}
- \li \l{QML Plugins}
- \li \l{Exposing C++ Models}
- \li \l{Integrating QML Code with Existing Qt UI Code}{Qt Gui Porting Information}
- \endlist
- \enddiv
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- Tools
- \enddiv
- \list
- \li \l{QML Internationalization}{Internationalization}
- \li \l{QtQuickTest Reference Documentation}
- \li \l{Debugging QML}
- \endlist
- \enddiv
-\enddiv
-\div {class="threecolumn_area"}
- \div {class="heading"}
- Qt Quick Elements
- \enddiv
- Qt Quick Elements features graphical elements, user input system,
- animation system, and data visualization through models and delegates.
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Graphics and Special Effects
- \enddiv
- \list
- \li \l{Basic Elements}{Basic Elements}
- \li \l{Painting with Canvas API}
- \li \l{Using the Qt Quick Particle System}{Particle Effects}
- \li \l{Shader Effects in QML}{Shader Effects}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Anchoring and Layouts
- \enddiv
- \list
- \li \l{Component Layouts}
- \li \l{Layouts with Anchors}
- \li \l{Right-to-left User Interfaces}{Right-to-left User Interfaces}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Mouse and Keyboard Input
- \enddiv
- \list
- \li \l{Mouse Events}{Mouse Events}
- \li \l{Text Handling and Validators}{Text Handling and Validators}
- \li \l{Keyboard Focus in QML}{Keyboard Focus}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- States and Transitions
- \enddiv
- \list
- \li \l{States}{States}
- \li \l{QML Animation and Transitions}{Animation and Transitions}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Data with Models and Views
- \enddiv
- \list
- \li {Models and Views}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Data Storage and Resources
- \enddiv
- \list
- \li \l{Local Storage}{SQL Local Storage}
- \li \l{Resource Loading and Network Transparency in QML}{Resources and Network Transparency}
- \endlist
- \enddiv
-\enddiv
-
-*/
-
+++ /dev/null
-/****************************************************************************
-**
-** 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.
-**
-**
-**
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
- \qmlmodule QtQuick 2
- \title QML Module QtQuick 2
-
- \brief The QML Elements
-
- This QML module contains all the QML elements that are
- instantiated as objects of C++ classes in the QtQml
- module. These elements work with the Scenegraph renderer and
- their own canvas.
- */
--- /dev/null
+/****************************************************************************
+**
+** 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 qml-properties-signals-methods.html
+\title C++ Properties, Methods, and Signals in QML
+\brief Exposing C++ properties, methods, and signals to QML
+\target qml-expose-properties
+
+\section1 Exposing Qt C++ Properties
+
+ The \l{The QML Engine}{QML engine} utilizes Qt's
+ \l{The Property System}{Property System} and in effect, QML
+ \l{Property Binding in QML}{property bindings} also use Qt properties.
+
+ Essentially, a Qt C++ property has a \e write function, \e read function,
+ and has a signal function. QML properties are inheritely public, both
+ readable and writable, albeit type-safe. QML properties may also have
+ signals which are emitted when the property value or binding changes.
+
+ The QML property equivalent of a Qt C++ property is created as a property
+ with the \l Q_PROPERTY() macro. There needs to be C++ functions assigned as
+ the property's read, write, and signal handler function.
+
+ The \l {register-c++-type}{Register a Type} section mentions that the
+ \c Person class has properties that are exposed to the QML context. The QML
+ properties are created with the \c Q_PROPERTY macro. The macro associates
+ the properties to the read, write, and singal functions in its argument.
+
+\code
+Q_PROPERTY(int size READ size WRITE setSize NOTIFY shoeChanged)
+\endcode
+
+ A \c Shoe class might have an integer property called \c size. We set the \c
+ size() function as the \c READ function and the \c setSize() function to be
+ the \c WRITE function. In a QML application, when a property is read, the \c
+ size() is called and when the property's binding changes, the \c setSize()
+ is called. The READ function, by definition, must return the same type as
+ the property.
+
+ We may also connect a \l{signals and slots}{signal} to a property. The \c
+ size property may have a \c shoeChanged signal indicated after the \c NOTIFY
+ parameter of the macro. The \c shoeChanged becomes a \l{QML Signal and
+ Handler Event System}{QML signal} and the runtime will create QML handler
+ called \c onShoeChanged. Whenever the size property's binding changes, the
+ \c shoeChanged signal is emitted and the \c onShoeChanged handler is
+ invoked. In the handler, commands such as \l{JavaScript Expressions in
+ QML}{JavaScript expressions} can perform clean-up operations or call other
+ functions.
+
+ \b{Note:} The QML signal handler will always be named
+ on<Property-name>Changed, regardless of the name used for the NOTIFY
+ signal in C++. We recommend using <property-name>Changed() for the
+ NOTIFY signal in C++.
+
+ We may also make the property a \c read-only property by placing
+ \c CONSTANT in the parameter. Changing the binding will generate an error.
+\code
+//A read-only property
+Q_PROPERTY(int size READ size CONSTANT)
+\endcode
+
+\section2 Default Property
+
+ When imported, QML components will bind their children to their designated
+ \l{default-property}{default property}. This is helpful, for example,
+ to redirect any declared child components to a property of another
+ component.
+
+ The runtime can set a property to be the default property by tagging the
+ property with \c DefaultProperty in The Q_CLASSINFO() macro.
+
+ \code
+ Q_CLASSINFO("DefaultProperty", "pipe")
+ \endcode
+
+ The property tagged as default property, \c pipe, can only be an object
+ property, or a list property.
+
+ A default property is optional. A derived class inherits its base class's
+ default property, but may override it in its own declaration. The \c pipe
+ property can refer to a property declared in the class itself, or a property
+ inherited from a base class.
+
+ The \l{Extending QML - Default Property Example}{Default Property} example
+ uses \l{default-property}{default properties} to assign the children of
+ a component to a specific property.
+
+ \section2 Grouped Properties
+
+ A property group may be functionally defined as a set of related properties.
+ For example, the \l{Layouts with Anchors}{anchors} are a group of
+ related properties. In practice, property groups resemble a parent object
+ where the individual properties are accessed as children.
+
+ A grouped property's member properties are accessed using the
+ <group>.<property> notation. For example, shoe.color is the way to access
+ the \c color property in the \c shoe property group .
+
+ \snippet examples/declarative/cppextensions/referenceexamples/grouped/example.qml ungrouped
+
+ Alternatively, the group can be accessed as a set.
+ \snippet examples/declarative/cppextensions/referenceexamples/grouped/example.qml grouped
+
+ A grouped property block is implemented as a read-only object property. The
+ \c shoe property shown is declared like this:
+
+ \snippet examples/declarative/cppextensions/referenceexamples/grouped/person.h 1
+
+ The \c ShoeDescription type declares the properties available to the grouped
+ property block - in this case the \c size, \c color, \c brand and \c price properties.
+
+ Grouped property blocks may declared and accessed be recusively.
+
+ \l {Extending QML - Grouped Properties Example} shows the complete code used to
+ implement the \c shoe property grouping.
+
+ \section2 Attached Properties
+
+ Attached properties annotate or add properties to another type or component.
+ For example, the \l Keys \e{attaching type} contains \e{attached properties}
+ that other elements may use to respond to key input. Conceptually, attached
+ properties are a \e type exporting a set of additional properties that can
+ be set on any other object instance.
+
+ The attaching type is a QObject derived type. The properties on the
+ attaching type are those that become available for use as attached
+ properties.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml 1
+
+ The \c BirthdayParty is called the attaching type and the
+ \c Boy instance the attachee object instance. The property \c rsvp is the
+ attached property.
+
+ Any Qt C++ type can become an attaching type by declaring the \c
+ qmlAttachedProperties() a public member function and declaring that the
+ class has QML_HAS_ATTACHED_PROPERTIES.
+
+ \code
+ static AttachedPropertiesType *qmlAttachedProperties(QObject *object);
+ \endcode
+
+ This static pointer returns an attachment object, of type \a
+ AttachedPropertiesType, for the attachee \a object instance. It is
+ customary, though not strictly required, for the attachment object to be
+ parented to \a object to prevent memory leaks.
+ The \l {Extending QML - Attached Properties Example}{Birthday}
+ class has \c BirthdayPartyAttached attached properties.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/birthdayparty.h static attached
+
+ The QML_DECLARE_TYPEINFO() macro can notify the runtime that the type has
+ attached properties with the QML_HAS_ATTACHED_PROPERTIES argument.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/birthdayparty.h declare attached
+
+ The qmlAttachedProperties method will be called at most once for each
+ attachee object instance. The QML engine will cache the returned instance
+ pointer for subsequent attached property accesses. Consequently the
+ attachment object may not be deleted until \a object is destroyed.
+
+ A common usage scenario is for a type to enhance the properties
+ available to its children in order to gather instance specific data.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml begin
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml rsvp
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml end
+
+ However, as a QML type cannot limit the instances to which the attachment
+ object must attach, the following is also allowed, even though adding a
+ birthday party rsvp in this context will have no effect. Instead, \c
+ BirthdayParty could be a separate component with a property \c rsvp.
+ \code
+ GraduationParty {
+ Boy { BirthdayParty.rsvp: "2009-06-01" }
+ }
+ \endcode
+
+ From C++, including the attaching type implementation, the attachment object
+ for an instance can be accessed using the following method:
+
+ \code
+ template<typename T>
+ QObject *qmlAttachedPropertiesObject<T>(QObject *attachee, bool create = true);
+ \endcode
+
+ This returns the attachment object attached to \a attachee by the attaching
+ type \a T. If type \a T is not a valid attaching type, this method always
+ returns 0. If \a create is true, a valid attachment object will always be
+ returned, creating it if it does not already exist. If \a create is false,
+ the attachment object will only be returned if it has previously been
+ created.
+
+ The \c rsvp properties of each guest in the \c Birthday party is accessible
+ through the \c qmlAttachedPropertiesObject function.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/attached/main.cpp query rsvp
+
+ The
+ \l {Extending QML - Attached Properties Example}{Attached Properties Example}
+ demonstrates the creation of attached properties with a birthday party
+ scenario.
+
+\section2 Object and List Properties
+
+ QML can set properties of types that are more complex than basic intrinsics like
+ integers and strings. Properties can also be object pointers, Qt interface
+ pointers, lists of object pointers, and lists of Qt interface pointers. As QML
+ is typesafe it ensures that only valid types are assigned to these properties,
+ just like it does for primitive types.
+
+ Properties that are pointers to objects or Qt interfaces are declared with the
+ Q_PROPERTY() macro, just like other properties. The \c host property
+ declaration looks like this:
+
+ \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 1
+
+ As long as the property type, in this case \c Person, is registered with QML the
+ property can be assigned.
+
+ QML also supports assigning Qt interfaces. To assign to a property whose type
+ is a Qt interface pointer, the interface must also be registered with QML. As
+ they cannot be instantiated directly, registering a Qt interface is different
+ from registering a new QML type. The following function is used instead:
+
+ \code
+ template<typename T>
+ int qmlRegisterInterface(const char *typeName)
+ \endcode
+
+ \c qmlRegisterInterface registers the C++ interface \a T with the QML system
+ as \a typeName.
+
+ Following registration, QML can coerce objects that implement this interface
+ for assignment to appropriately typed properties.
+
+
+ \snippet examples/declarative/cppextensions/referenceexamples/properties/example.qml 0
+
+ The \c guests property is a \e{list property} of \c Person objects. A list
+ of \c Person objects are bound to the \c BirthdayParty's \c host property,
+ and assigns three \c Person objects to the guests property.
+
+ Properties that are lists of objects or Qt interfaces are also declared with
+ the Q_PROPERTY() macro. However, list properties must have the type
+ \l{QQmlListProperty}{QQmlListProperty<T>}.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 2
+
+ As with the other property types, the type of list content, \a T, must be
+ \l{register-c++-type}{registered} into the runtime.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/properties/main.cpp register list
+
+ \l {Extending QML - Object and List Property Types Example} shows the
+ complete code used to create the \c BirthdayParty type. For more
+ information, visit \l{QQmlListProperty}{QQmlListProperty<T>}
+ for creating list properties.
+
+\section2 Sequence Types
+
+ Certain C++ sequence types are supported transparently in QML as JavaScript
+ Array types.
+ In particular, QML currently supports:
+ \list
+ \li \c {QList<int>}
+ \li \c {QList<qreal>}
+ \li \c {QList<bool>}
+ \li \c {QList<QString>} and \c{QStringList}
+ \li \c {QList<QUrl>}
+ \endlist
+
+ These sequence types are implemented directly in terms of the underlying C++
+ sequence. There are two ways in which such sequences can be exposed to QML:
+ as a Q_PROPERTY of the given sequence type; or as the return type of a
+ Q_INVOKABLE method. There are some differences in the way these are
+ implemented, which are important to note.
+
+ If the sequence is exposed as a Q_PROPERTY, accessing any value in the
+ sequence by index will cause the sequence data to be read from the QObject's
+ property, then a read to occur. Similarly, modifying any value in the
+ sequence will cause the sequence data to be read, and then the modification
+ will be performed and the modified sequence will be written back to the
+ QObject's property.
+
+ If the sequence is returned from a Q_INVOKABLE function, access and mutation
+ is much cheaper, as no QObject property read or write occurs; instead, the
+ C++ sequence data is accessed and modified directly.
+
+ Other sequence types are not supported transparently, and instead an
+ instance of any other sequence type will be passed between QML and C++ as an
+ opaque QVariantList.
+
+ \b {Important Note:} There are some minor differences between the
+ semantics of such sequence Array types and default JavaScript Array types
+ which result from the use of a C++ storage type in the implementation. In
+ particular, deleting an element from an Array will result in a
+ default-constructed value replacing that element, rather than an Undefined
+ value. Similarly, setting the length property of the Array to a value larger
+ than its current value will result in the Array being padded out to the
+ specified length with default-constructed elements rather than Undefined
+ elements. Finally, the Qt container classes support signed (rather than
+ unsigned) integer indexes; thus, attempting to access any index greater
+ than INT_MAX will fail.
+
+ The default-constructed values for each sequence type are as follows:
+ \table
+ \row \li QList<int> \li integer value 0
+ \row \li QList<qreal> \li real value 0.0
+ \row \li QList<bool> \li boolean value \c {false}
+ \row \li QList<QString> and QStringList \li empty QString
+ \row \li QList<QUrl> \li empty QUrl
+ \endtable
+
+ If you wish to remove elements from a sequence rather than simply replace
+ them with default constructed values, do not use the indexed delete operator
+ ("delete sequence[i]") but instead use the \c {splice} function
+ ("sequence.splice(startIndex, deleteCount)").
+
+
+\section2 Property Signals
+
+ All properties on custom types automatically support property binding.
+ However, for binding to work correctly, QML must be able to reliably
+ determine when a property has changed so that it knows to reevaluate any
+ bindings that depend on the property's value. QML relies on the presence of
+ a \l {Qt's Property System}{NOTIFY signal} for this determination.
+
+ Here is the \c host property declaration:
+
+ \snippet examples/declarative/cppextensions/referenceexamples/binding/birthdayparty.h 0
+
+ The NOTIFY attribute is followed by a signal name. It is the responsibility
+ of the class implementer to ensure that whenever the property's value
+ changes, the NOTIFY signal is emitted. The signature of the NOTIFY signal is
+ not important to QML.
+
+ To prevent loops or excessive evaluation, developers should ensure that the
+ signal is only emitted whenever the property's value is actually changed. If
+ a property, or group of properties, is infrequently used it is permitted to
+ use the same NOTIFY signal for several properties. This should be done with
+ care to ensure that performance doesn't suffer.
+
+ To keep QML reliable, if a property does not have a NOTIFY signal, it cannot
+ be used in a binding expression. However, the property can still be assigned
+ a binding as QML does not need to monitor the property for change in that
+ scenario.
+
+ Consider a custom type, \c TestElement, that has two properties, \c a and
+ \c b. Property \c a does \e not have a NOTIFY signal, and property \c b does
+ have a NOTIFY signal.
+
+ \code
+ TestElement {
+ // This is OK
+ a: b
+ }
+ TestElement {
+ // Will NOT work
+ b: a
+ }
+ \endcode
+
+ The presence of a NOTIFY signal does incur a small overhead. There are cases
+ where a property's value is set at object construction time, and does not
+ subsequently change. The most common case of this is when a type uses \l
+ {Grouped Properties}, and the grouped property object is allocated once, and
+ only freed when the object is deleted. In these cases, the CONSTANT
+ attribute may be added to the property declaration instead of a NOTIFY
+ signal.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/binding/person.h 0
+
+ Extreme care must be taken here or applications using your type may misbehave.
+ The CONSTANT attribute should only be used for properties whose value is set,
+ and finalized, only in the class constructor. All other properties that want
+ to be used in bindings should have a NOTIFY signal instead.
+
+ \l {Extending QML - Binding Example} shows the BirthdayParty example updated to
+ include NOTIFY signals for use in binding.
+
+\section1 Signals Support
+
+ A \l{signals and slots}{signal} in Qt C++ is readily available as a
+ \l{QML Signal and Handler Event System}{QML signal}. A signal will have
+ a corresponding signal \e{handler}, created automatically. The handler
+ name will have \c on prepended at the beginning of the name. The first
+ character of the signal is uppercased for the signal handler. The
+ signal parameter is also availabe to the QML signal.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/signal/birthdayparty.h 0
+ The QML engine will create a handler for the \c partyStarted signal
+ called \c onPartyStarted.
+ \snippet examples/declarative/cppextensions/referenceexamples/signal/example.qml 0
+
+ Classes may have multiple signals with the same name, but only the final
+ signal is accessible as a QML signal. Note that signals with the same name
+ but different parameters cannot be distinguished from one another.
+
+ Signal parameters are exposed and can be any one of the QML
+ \l{QML Basic Types}{basic types} as well registered object types. Accessing
+ unregistered types will not generate an error, but the parameter value will
+ not be accessible from the handler.
+
+ To use signals from items not created in QML, access their signals with the
+ \l {Connections} element.
+
+ Additionally, if a property is added to a C++ class, all QML elements
+ based on that C++ class will have a \e{value-changed} signal handler
+ for that property. The name of the signal handler is
+ \e{on<Property-name>Changed}, with the first letter of the property
+ name being upper case.
+
+ The \l {Extending QML - Signal Support Example}{Signal Support Example}
+ shows an example application exposing signals to a QML component.
+
+\section1 Exposing Methods
+
+ The Q_INVOKABLE macro exposes any Qt C++ method as a QML method.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/methods/birthdayparty.h 0
+
+ In a QML file, we can invoke the method as we would a
+ \l{JavaScript Expressions in QML}{JavaScript expression}.
+ \snippet examples/declarative/cppextensions/referenceexamples/methods/example.qml 0
+
+ \l {Extending QML - Methods Example}{Methods example} uses the Q_INVOKABLE
+ method to expose methods and demonstrates some usages of the method in
+ an application.
+
+ An alternative to the Q_INVOKABLE macro is to declare the C++ method as a
+ \l{signals and slot}{slot}.
+
+ \code
+ slots:
+ void invite(const QString &name);
+ \endcode
+
+
+*/
--- /dev/null
+/****************************************************************************
+**
+** 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 qml-plugin.html
+\title QML Plugins and C++ Binding
+\brief Provides an engine for running QML code
+
+To add functionality that is beyond QML and modules, C++ types are registered to
+the runtime as plugins. For example, to add a full network manager into
+QML, classes that utilize Qt Network classes may be registered into the runtime
+and loaded as a QML type.
+
+Additional C++ types are also available in applications through this mechanism.
+
+\section1 C++ Types as QML Types
+
+The QML engine can instantiate any Qt C++ construct such as properties,
+functions, and data models into the QML context allowing the constructs to be
+accessible from within QML.
+
+ \list
+ \li \l{C++ Types as QML Types}
+ \li \l{C++ Properties, Methods, and Signals in QML}
+ \endlist
+
+\section1 Registering a Plugin
+The QML engine can run Qt C++ applications by registering types into the runtime
+and by loading C++ code as plugins. Plugins are imported and labeled as modules
+and its content are available as types.
+
+ To write a QML extension plugin:
+ \list 1
+ \li Subclass QDeclarativeExtensionPlugin
+ \li Implement QDeclarativeExtensionPlugin's registerTypes() method
+ \li Register types with qmlRegisterType()
+ \li Export the class using the Q_EXPORT_PLUGIN2() macro
+ \li Write a project file for the plugin
+ \li Add the files to the project
+ \endlist
+
+ The QML Plugins page details the process using example code.
+ \list
+ \li \l{QML Plugins}
+ \endlist
+*/
The \c TimeModel class receives a \c{1.0} version of this plugin library, as
a QML type called \c Time. The Q_ASSERT() macro can ensure the module is
imported correctly by any QML components that use this plugin. The
- \l{Creating QML Types} article has more information about registering C++
+ \l{C++ Types as QML Types} article has more information about registering C++
types into the runtime.
For this example, the TimeExample source directory is in
\list
\li \l {Tutorial: Writing QML extensions with C++} - contains a chapter
on creating QML plugins.
- \li \l{Creating QML Types} - information about registering C++ types into
+ \li \l{C++ Types as QML Types} - information about registering C++ types into
the runtime.
\li \l{How to Create Qt Plugins} - information about Qt plugins
\endlist
--- /dev/null
+/****************************************************************************
+**
+** 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 qml-c++types.html
+\title C++ Types as QML Types
+\brief exposing Qt C++ types into the QML engine
+
+The \l{The QML Engine}{QML engine} can instantiate any Qt C++ construct
+such as \l{The Property System}{properties}, functions, and data models into
+the QML context allowing the constructs to be accessible from within QML.
+
+\target register-c++-type
+\section1 Register a Type
+
+ In an application or a \l{QML Plugins}{plugin}, the \c qmlRegisterType
+ template will register a class to the QML engine.
+
+\code
+template<typename T>
+int qmlRegisterType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
+\endcode
+
+ \l qmlRegisterType() registers the C++ type \a T with the QML system, and
+ makes it available to the QML context under the name \c qmlName in library
+ \c uri version \c versionMajor.versionMinor. The \c qmlName can be the same
+ as the C++ type name.
+
+ Suppose that a \c Person class defined in a C++ is to be exposed into the
+ QML context. The class must be a subclass of \l{QObject} and have a default
+ constructor. The \l{The Property System}{properties} created with the
+ Q_PROPERTY macro are visible in the QML context as well.
+ \snippet declarative/cppextensions/referenceexamples/adding/person.h 0
+
+ The application registers the class to the runtime with the
+ \l{qmlRegisterType()}.
+
+ \snippet declarative/cppextensions/referenceexamples/adding/main.cpp 0
+
+ The Person type is then imported with the \c "People 1.0" module and its
+ properties are accessible in a QML file.
+\snippet declarative/cppextensions/referenceexamples/adding/example.qml 0
+
+ The \l {Extending QML - Adding Types Example}{Adding Types} example
+ demonstrates as usage of the \l qmlRegisterType().
+
+ Alternatively, these functions provide a way for other types of C++ types
+ to be visible in the QML context.
+ \list
+ \li \l qmlRegisterModuleApi() is suited for registering either a QJSValue
+ or QObject module API (shared instance) into a namespace
+ \li \l qmlRegisterUncreatableType() is suited for attached
+ properties and enum types.
+ \li \l qmlRegisterTypeNotAvailable() is for
+ reserving a namespace and suited for generating useful errors.
+ \li \l qmlRegisterInterface() - for registering base or abstract classes for
+ \l{qml-c++-coercion}{coercion and inheritance}. This is useful for general
+ Qt objects or \l{Qt Objects and Interfaces}{pointers} to objects.
+ \li \l qmlRegisterExtendedType() - for \l{qml-c++-extension}{extended types}
+ \endlist
+
+ \section2 Qt Objects and Interfaces
+ QML can bind to complex objects such as pointers to objects or lists. As QML
+ is typesafe, the \l{The QML Engine}{QML engine} ensures that only
+ valid types are assigned to these properties.
+
+ The QML engine treats pointers to objects or Qt interfaces the same
+ way as regular properties. Thus, the lists or pointers are created as
+ properties using the Q_PROPERTY() macro.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 1
+
+ The \c host is an \l{qml-expose-properties}{exposed property} that can bind
+ to objects or lists of objects. The property type, in this case \c Person,
+ must be \l{register-c++-type}{registered} into the runtime.
+
+ QML also supports assigning Qt interfaces. To assign to a property whose
+ type is a Qt interface pointer, the interface must also be registered with
+ QML. As they cannot be instantiated directly, registering a Qt interface is
+ different from registering a new QML type. The following function is used
+ instead:
+
+ \code
+ template<typename T>
+ int qmlRegisterInterface(const char *typeName)
+ \endcode
+
+ This function registers the C++ interface \a T with the QML system as \a
+ typeName.
+
+ Following registration, QML can \l{qml-c++-coercion}{coerce} objects that
+ implement this interface for assignment to appropriately typed properties.
+
+\section1 Type Revisions and Versions
+
+ Type revisions and versions allow new properties or methods to exist in the
+ new version while remaining compatible with previous versions.
+
+ Consider these two QML files:
+ \code
+ // main.qml
+ import QtQuick 1.0
+ Item {
+ id: root
+ MyComponent {}
+ }
+ \endcode
+
+ \code
+ // MyComponent.qml
+ import MyModule 1.0
+ CppItem {
+ value: root.x
+ }
+ \endcode
+ where \c CppItem maps to the C++ class \c QCppItem.
+
+ If the author of QCppItem adds a \c root property to QCppItem in a new
+ version of the module, \c root.x now resolves to a different value because
+ \c root is also the \c id of the top level component. The author could
+ specify that the new \c root property is available from a specific minor
+ version. This permits new properties and features to be added to existing
+ elements without breaking existing programs.
+
+ The REVISION tag is used to mark the \c root property as added in revision 1
+ of the class. Methods such as Q_INVOKABLE's, signals and slots can also be
+ tagged for a revision using the \c Q_REVISION(x) macro:
+
+ \code
+ class CppElement : public BaseObject
+ {
+ Q_OBJECT
+ Q_PROPERTY(int root READ root WRITE setRoot NOTIFY rootChanged REVISION 1)
+
+ signals:
+ Q_REVISION(1) void rootChanged();
+ };
+ \endcode
+
+ To register the new class revision to a particular version the following function is used:
+
+ \code
+ template<typename T, int metaObjectRevision>
+ int qmlRegisterType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
+ \endcode
+
+ To register \c CppElement version 1 for \c {MyModule 1.1}:
+
+ \code
+ qmlRegisterType<QCppElement,1>("MyModule", 1, 1, "CppElement")
+ \endcode
+
+ \c root is only available when MyModule 1.1 is imported.
+
+ For the same reason, new elements introduced in later versions should use
+ the minor version argument of qmlRegisterType.
+
+ This feature of the language allows for behavioural changes to be made
+ without breaking existing applications. Consequently QML module authors
+ should always remember to document what changed between minor versions, and
+ QML module users should check that their application still runs correctly
+ before deploying an updated import statement.
+
+ You may also register the revision of a base class that your module depends upon
+ using the qmlRegisterRevision() function:
+
+ \code
+ template<typename T, int metaObjectRevision>
+ int qmlRegisterRevision(const char *uri, int versionMajor, int versionMinor)
+ \endcode
+
+ For example, if \c BaseObject is changed and now has a revision 1, you can specify that
+ your module uses the new revision:
+
+ \code
+ qmlRegisterRevision<BaseObject,1>("MyModule", 1, 1);
+ \endcode
+
+ This is useful when deriving from base classes not declared as part of your
+ module, e.g. when extending classes from the QtQuick library.
+
+ The revision feature of QML allows for behavioral changes without breaking
+ existing applications. Consequently, QML module authors should always
+ remember to document what changed between minor versions, and QML module
+ users should check that their application still runs correctly before
+ deploying an updated import statement.
+
+\target qml-c++-coercion
+\section1 Inheritance and Coercion
+
+ QML supports C++ inheritance hierarchies and can freely coerce between
+ known, valid object types. This enables the creation of common base classes
+ that allow the assignment of specialized classes to object or list
+ properties.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/coercion/example.qml 0
+
+ The QML snippet shown above assigns a \c Boy object to the \c
+ BirthdayParty's \c host property, and assigns three other objects to the \c
+ guests property. Both the \c host and the \c guests properties binds to the
+ \c Person type, but the assignment is valid as both the \c Boy and \c Girl
+ objects inherit from \c Person.
+
+ To assign to a property, the property's type must have been
+ \l{register-c++-type}{registered} to the \l{The QML Engine}{declarative
+ runtime}. If a type that acts purely as a base class that cannot be
+ instantiated from QML needs to be registered as well. The
+ \l qmlRegisterType() is useful for this occasion.
+
+ \code
+ template<typename T>
+ int qmlRegisterType()
+ \endcode
+
+ This function registers the C++ type \a T with the QML system. The
+ parameterless call to the template function qmlRegisterType() does not
+ define a mapping between the C++ class and a QML element name, so the type
+ is not instantiable from QML, but it is available for type coercion.
+
+ \snippet examples/declarative/cppextensions/referenceexamples/coercion/main.cpp 0
+ \snippet examples/declarative/cppextensions/referenceexamples/coercion/main.cpp register boy girl
+ The \c Person class is registered withouth the parameters. Both the
+ \c Boy and \c Girl class derive from the \c Person class.
+
+ Type \a T must inherit QObject, but there are no restrictions on whether it
+ is concrete or the signature of its constructor.
+
+ QML will automatically coerce C++ types when assigning to either an object
+ property, or to a list property. Only if coercion fails does an assignment
+ error occur.
+
+ The \l{Extending QML - Inheritance and Coercion Example}{Inheritance and Coercion Example}
+ shows the complete code used to create the \c Boy and \c Girl types.
+
+\target qml-c++-extension
+\section1 Extension Objects
+
+ \snippet examples/declarative/cppextensions/referenceexamples/extended/example.qml 0
+
+ The \c leftMargin property is a new property to an existing C++ type,
+ \l QLineEdit, without modifying its source code.
+
+ When integrating existing classes and technology into QML, APIs will
+ often need tweaking to fit better into the declarative environment.
+ Although the best results are usually obtained by modifying the original
+ classes directly, if this is either not possible or is complicated by some
+ other concerns, extension objects allow limited extension possibilities
+ without direct modifications.
+
+ \e{Extension objects} add additional properties to an existing type.
+ Extension objects can only add properties, not signals or methods. An
+ extended type definition allows the programmer to supply an additional type,
+ known as the \e{extension type}, when registering the class. The
+ properties are transparently merged with the original target class when used
+ from within QML.
+
+ The \l qmlRegisterExtendedType() is for registering extended types. Note
+ that it has two forms.
+ \code
+ template<typename T, typename ExtendedT>
+ int qmlRegisterExtendedType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
+
+ template<typename T, typename ExtendedT>
+ int qmlRegisterExtendedType()
+ \endcode
+ functions should be used instead of the regular \c qmlRegisterType() variations.
+ The arguments are identical to the corresponding non-extension registration functions,
+ except for the ExtendedT parameter which is the type
+ of the extension object.
+
+ An extension class is a regular QObject, with a constructor that takes a
+ QObject pointer. However, the extension class creation is delayed until the
+ first extended property is accessed. The extension class is created and the
+ target object is passed in as the parent. When the property on the original
+ is accessed, the corresponding property on the extension object is used
+ instead.
+
+ The \l{Extending QML - Extension Objects}{Extension Objects} example
+ demonstrates a usage of extension objects.
+
+\section1 Property Value Sources
+
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/example.qml 0
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/example.qml 1
+
+The QML snippet shown above applies a property value source to the \c announcement property.
+A property value source generates a value for a property that changes over time.
+
+Property value sources are most commonly used to do animation. Rather than
+constructing an animation object and manually setting the animation's "target"
+property, a property value source can be assigned directly to a property of any
+type and automatically set up this association.
+
+The example shown here is rather contrived: the \c announcement property of the
+\c BirthdayParty object is a string that is printed every time it is assigned and
+the \c HappyBirthdaySong value source generates the lyrics of the song
+"Happy Birthday".
+
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/birthdayparty.h 0
+
+Normally, assigning an object to a string property would not be allowed. In
+the case of a property value source, rather than assigning the object instance
+itself, the QML engine sets up an association between the value source and
+the property.
+
+Property value sources are special types that derive from the
+QQmlPropertyValueSource base class. This base class contains a single method,
+QQmlPropertyValueSource::setTarget(), that the QML engine invokes when
+associating the property value source with a property. The relevant part of
+the \c HappyBirthdaySong type declaration looks like this:
+
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 0
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 1
+\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 2
+
+In all other respects, property value sources are regular QML types. They must
+be registered with the QML engine using the same macros as other types, and can
+contain properties, signals and methods just like other types.
+
+When a property value source object is assigned to a property, QML first tries
+to assign it normally, as though it were a regular QML type. Only if this
+assignment fails does the engine call the \l {QQmlPropertyValueSource::}{setTarget()} method. This allows
+the type to also be used in contexts other than just as a value source.
+
+\l {Extending QML - Property Value Source Example} shows the complete code used
+to implement the \c HappyBirthdaySong property value source.
+
+\section1 Optimization and Other Considerations
+
+The \l{qml-engine-optimization}{ QML Engine} article suggests possible
+optimization considerations as memory management and QVariant type usages.
+
+*/
****************************************************************************/
/*!
-\target qmlengine
\page qmlengine.html
\ingroup qml-features
\title The QML Engine
side, all QML object data is automatically made available to the meta-object
system and can be accessed from C++.
- The \l{Creating QML Types} article covers the topic of exposing Qt functions
+ The \l{C++ Types as QML Types} article covers the topic of exposing Qt functions
and properties to the declarative engine.
\section2 Calling Functions
changes. If you are using custom types in QML, make sure their properties
have NOTIFY signals so that they can be used in property bindings.
- The \l{Creating QML Types} article covers the topic of exposing Qt
+ The \l{C++ Types as QML Types} article covers the topic of exposing Qt
properties to the runtime. For more information, the
\l{Tutorial: Writing QML extensions with C++}{Writing QML extensions with C++}
tutorial demonstrates basic usage patterns.
\annotatedlist qmlbasictypes
To create additional types, such as data types created in C++, read the
- \l{Creating QML Types} article.
+ \l{C++ Types as QML Types} article.
*/
/*!
****************************************************************************/
/*!
-\page qml-modules.html
+\page qmllanguage-modules.html
\title QML Modules
-\brief creating and setting up QML modules
+\brief creating and importing QML modules
\section1 Modules
method.
For complete information on events from the runtime or creating signals from the
-runtime, read the \l{The QML Engine} and the \l{Creating QML Types} articles.
+runtime, read the \l{The QML Engine} and the \l{C++ Types as QML Types} articles.
*/
--- /dev/null
+/****************************************************************************
+**
+** 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 qmllanguage.html
+\ingroup qt-gui-concepts
+\ingroup overviews
+\title QML - the Declarative Language
+\brief Provides a declarative language for building highly
+dynamic applications.
+
+QML is a declarative language for creating flexible and reusable types. The
+language features property binding, signal and handler event system, and a
+mechanism to bind to the Qt Framework. JavaScript expressions bind to properties
+to create dynamic applications.
+
+\section1 Types and Properties
+ \list
+ \li \l{QML Types and Properties}
+ \endlist
+
+\section1 Event System
+ \list
+ \li \l{QML Signal and Handler Event System}{Signal and Handler Event System}
+ \endlist
+
+\section1 JavaScript Expressions
+ \list
+ \li \l{JavaScript Expressions}
+ \endlist
+
+\section1 Imports and Namespaces
+ \list
+ \li \l{QML Modules}{Modules}
+ \endlist
+
+\section1 Tools and Debugging
+ \list
+ \li \l{Debugging QML}
+ \li \l{QtQuickTest Reference Documentation}
+ \endlist
+
+\section1 Reference
+ \list
+ \li \l{QML Internationalization}{Internationalization}
+ \li \l{QML Coding Conventions}{Coding Conventions}
+ \li \l{QML Security}{Security Model}
+ \li \l{QML Scope}{Scope Model}
+ \li \l{QML Documents}{Documents}
+ \li \l{QML Syntax}
+ \li \l{QML Performance}{Performance}
+ \endlist
+*/
--- /dev/null
+/****************************************************************************
+**
+** 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 qmllanguage.html
+\ingroup qt-gui-concepts
+\ingroup overviews
+\title QML
+\brief Provides a declarative language for building highly
+dynamic applications.
+
+QML is a declarative language for creating flexible and reusable types. The
+language features property binding, signal and handler event system, and a
+mechanism to bind to the Qt Framework. JavaScript expressions bind to properties
+to create dynamic applications.
+
+
+\list
+ \li QML Introduction
+\endlist
+
+\section1 Types and Properties
+ \list
+ \li \l{QML Basic Types}{Basic Types}
+ \li QML Types
+ \li \l{QML Components}{Components}
+ \li \l{Properties and Property Binding in QML}{Properties and Property Binding}
+ \li \l{QML Syntax}
+ \endlist
+
+\section1 Event System
+ \list
+ \li \l{QML Signal and Handler Event System}{Signal and Handler Event System}
+ \endlist
+
+\section1 JavaScript Expressions
+ \list
+ \li \l{List of JavaScript Objects and Functions}
+ \li \l{JavaScript Expressions in QML}{JavaScript Reference}
+ \endlist
+
+\section1 Imports and Namespaces
+ \list
+ \li \l{QML Modules}{Modules}
+ \endlist
+
+\section1 Managing QML Objects
+ \list
+ \li \l{Dynamic Object Management in QML}{Dynamic Object Management}
+ \li \l{QML Performance}{Performance}
+ \endlist
+
+\section1 Reference
+ \list
+ \li \l{QML Internationalization}{Internationalization}
+ \li \l{QtQuickTest Reference Documentation}
+ \li \l{Debugging QML}
+ \li \l{QML Coding Conventions}{Coding Conventions}
+ \li \l{QML Security}{Security Model}
+ \li \l{QML Scope}{Scope Model}
+ \li \l{QML Documents}{Documents}
+ \endlist
+*/
+++ /dev/null
-/****************************************************************************
-**
-** 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 qml-c++types.html
-\title Creating QML Types
-\brief exposing Qt C++ types into the QML engine
-
-The \l{The QML Engine}{QML engine} can instantiate any Qt C++ construct
-such as \l{The Property System}{properties}, functions, and data models into
-the QML context allowing the constructs to be accessible from within QML.
-
-\target register-c++-type
-\section1 Register a Type
-
- In an application or a \l{QML Plugins}{plugin}, the \c qmlRegisterType
- template will register a class to the QML engine.
-
-\code
-template<typename T>
-int qmlRegisterType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
-\endcode
-
- \l qmlRegisterType() registers the C++ type \a T with the QML system, and
- makes it available to the QML context under the name \c qmlName in library
- \c uri version \c versionMajor.versionMinor. The \c qmlName can be the same
- as the C++ type name.
-
- Suppose that a \c Person class defined in a C++ is to be exposed into the
- QML context. The class must be a subclass of \l{QObject} and have a default
- constructor. The \l{The Property System}{properties} created with the
- Q_PROPERTY macro are visible in the QML context as well.
- \snippet declarative/cppextensions/referenceexamples/adding/person.h 0
-
- The application registers the class to the runtime with the
- \l{qmlRegisterType()}.
-
- \snippet declarative/cppextensions/referenceexamples/adding/main.cpp 0
-
- The Person type is then imported with the \c "People 1.0" module and its
- properties are accessible in a QML file.
-\snippet declarative/cppextensions/referenceexamples/adding/example.qml 0
-
- The \l {Extending QML - Adding Types Example}{Adding Types} example
- demonstrates as usage of the \l qmlRegisterType().
-
- Alternatively, these functions provide a way for other types of C++ types
- to be visible in the QML context.
- \list
- \li \l qmlRegisterModuleApi() is suited for registering either a QJSValue
- or QObject module API (shared instance) into a namespace
- \li \l qmlRegisterUncreatableType() is suited for attached
- properties and enum types.
- \li \l qmlRegisterTypeNotAvailable() is for
- reserving a namespace and suited for generating useful errors.
- \li \l qmlRegisterInterface() - for registering base or abstract classes for
- \l{qml-c++-coercion}{coercion and inheritance}. This is useful for general
- Qt objects or \l{Qt Objects and Interfaces}{pointers} to objects.
- \li \l qmlRegisterExtendedType() - for \l{qml-c++-extension}{extended types}
- \endlist
-
- \section2 Qt Objects and Interfaces
- QML can bind to complex objects such as pointers to objects or lists. As QML
- is typesafe, the \l{The QML Engine}{QML engine} ensures that only
- valid types are assigned to these properties.
-
- The QML engine treats pointers to objects or Qt interfaces the same
- way as regular properties. Thus, the lists or pointers are created as
- properties using the Q_PROPERTY() macro.
-
- \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 1
-
- The \c host is an \l{qml-expose-properties}{exposed property} that can bind
- to objects or lists of objects. The property type, in this case \c Person,
- must be \l{register-c++-type}{registered} into the runtime.
-
- QML also supports assigning Qt interfaces. To assign to a property whose
- type is a Qt interface pointer, the interface must also be registered with
- QML. As they cannot be instantiated directly, registering a Qt interface is
- different from registering a new QML type. The following function is used
- instead:
-
- \code
- template<typename T>
- int qmlRegisterInterface(const char *typeName)
- \endcode
-
- This function registers the C++ interface \a T with the QML system as \a
- typeName.
-
- Following registration, QML can \l{qml-c++-coercion}{coerce} objects that
- implement this interface for assignment to appropriately typed properties.
-
-\target qml-expose-properties
-\section1 Exposing Qt C++ Properties
-
- The \l{The QML Engine}{QML engine} utilizes Qt's
- \l{The Property System}{Property System} and in effect, QML
- \l{Property Binding in QML}{property bindings} also use Qt properties.
-
- Essentially, a Qt C++ property has a \e write function, \e read function,
- and has a signal function. QML properties are inheritely public, both
- readable and writable, albeit type-safe. QML properties may also have
- signals which are emitted when the property value or binding changes.
-
- The QML property equivalent of a Qt C++ property is created as a property
- with the \l Q_PROPERTY() macro. There needs to be C++ functions assigned as
- the property's read, write, and signal handler function.
-
- The \l {register-c++-type}{Register a Type} section mentions that the
- \c Person class has properties that are exposed to the QML context. The QML
- properties are created with the \c Q_PROPERTY macro. The macro associates
- the properties to the read, write, and singal functions in its argument.
-
-\code
-Q_PROPERTY(int size READ size WRITE setSize NOTIFY shoeChanged)
-\endcode
-
- A \c Shoe class might have an integer property called \c size. We set the \c
- size() function as the \c READ function and the \c setSize() function to be
- the \c WRITE function. In a QML application, when a property is read, the \c
- size() is called and when the property's binding changes, the \c setSize()
- is called. The READ function, by definition, must return the same type as
- the property.
-
- We may also connect a \l{signals and slots}{signal} to a property. The \c
- size property may have a \c shoeChanged signal indicated after the \c NOTIFY
- parameter of the macro. The \c shoeChanged becomes a \l{QML Signal and
- Handler Event System}{QML signal} and the runtime will create QML handler
- called \c onShoeChanged. Whenever the size property's binding changes, the
- \c shoeChanged signal is emitted and the \c onShoeChanged handler is
- invoked. In the handler, commands such as \l{JavaScript Expressions in
- QML}{JavaScript expressions} can perform clean-up operations or call other
- functions.
-
- \b{Note:} The QML signal handler will always be named
- on<Property-name>Changed, regardless of the name used for the NOTIFY
- signal in C++. We recommend using <property-name>Changed() for the
- NOTIFY signal in C++.
-
- We may also make the property a \c read-only property by placing
- \c CONSTANT in the parameter. Changing the binding will generate an error.
-\code
-//A read-only property
-Q_PROPERTY(int size READ size CONSTANT)
-\endcode
-
-\section2 Default Property
-
- When imported, QML components will bind their children to their designated
- \l{default-property}{default property}. This is helpful, for example,
- to redirect any declared child components to a property of another
- component.
-
- The runtime can set a property to be the default property by tagging the
- property with \c DefaultProperty in The Q_CLASSINFO() macro.
-
- \code
- Q_CLASSINFO("DefaultProperty", "pipe")
- \endcode
-
- The property tagged as default property, \c pipe, can only be an object
- property, or a list property.
-
- A default property is optional. A derived class inherits its base class's
- default property, but may override it in its own declaration. The \c pipe
- property can refer to a property declared in the class itself, or a property
- inherited from a base class.
-
- The \l{Extending QML - Default Property Example}{Default Property} example
- uses \l{default-property}{default properties} to assign the children of
- a component to a specific property.
-
- \section2 Grouped Properties
-
- A property group may be functionally defined as a set of related properties.
- For example, the \l{Layouts with Anchors}{anchors} are a group of
- related properties. In practice, property groups resemble a parent object
- where the individual properties are accessed as children.
-
- A grouped property's member properties are accessed using the
- <group>.<property> notation. For example, shoe.color is the way to access
- the \c color property in the \c shoe property group .
-
- \snippet examples/declarative/cppextensions/referenceexamples/grouped/example.qml ungrouped
-
- Alternatively, the group can be accessed as a set.
- \snippet examples/declarative/cppextensions/referenceexamples/grouped/example.qml grouped
-
- A grouped property block is implemented as a read-only object property. The
- \c shoe property shown is declared like this:
-
- \snippet examples/declarative/cppextensions/referenceexamples/grouped/person.h 1
-
- The \c ShoeDescription type declares the properties available to the grouped
- property block - in this case the \c size, \c color, \c brand and \c price properties.
-
- Grouped property blocks may declared and accessed be recusively.
-
- \l {Extending QML - Grouped Properties Example} shows the complete code used to
- implement the \c shoe property grouping.
-
- \section2 Attached Properties
-
- Attached properties annotate or add properties to another type or component.
- For example, the \l Keys \e{attaching type} contains \e{attached properties}
- that other elements may use to respond to key input. Conceptually, attached
- properties are a \e type exporting a set of additional properties that can
- be set on any other object instance.
-
- The attaching type is a QObject derived type. The properties on the
- attaching type are those that become available for use as attached
- properties.
-
- \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml 1
-
- The \c BirthdayParty is called the attaching type and the
- \c Boy instance the attachee object instance. The property \c rsvp is the
- attached property.
-
- Any Qt C++ type can become an attaching type by declaring the \c
- qmlAttachedProperties() a public member function and declaring that the
- class has QML_HAS_ATTACHED_PROPERTIES.
-
- \code
- static AttachedPropertiesType *qmlAttachedProperties(QObject *object);
- \endcode
-
- This static pointer returns an attachment object, of type \a
- AttachedPropertiesType, for the attachee \a object instance. It is
- customary, though not strictly required, for the attachment object to be
- parented to \a object to prevent memory leaks.
- The \l {Extending QML - Attached Properties Example}{Birthday}
- class has \c BirthdayPartyAttached attached properties.
-
- \snippet examples/declarative/cppextensions/referenceexamples/attached/birthdayparty.h static attached
-
- The QML_DECLARE_TYPEINFO() macro can notify the runtime that the type has
- attached properties with the QML_HAS_ATTACHED_PROPERTIES argument.
-
- \snippet examples/declarative/cppextensions/referenceexamples/attached/birthdayparty.h declare attached
-
- The qmlAttachedProperties method will be called at most once for each
- attachee object instance. The QML engine will cache the returned instance
- pointer for subsequent attached property accesses. Consequently the
- attachment object may not be deleted until \a object is destroyed.
-
- A common usage scenario is for a type to enhance the properties
- available to its children in order to gather instance specific data.
-
- \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml begin
- \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml rsvp
- \snippet examples/declarative/cppextensions/referenceexamples/attached/example.qml end
-
- However, as a QML type cannot limit the instances to which the attachment
- object must attach, the following is also allowed, even though adding a
- birthday party rsvp in this context will have no effect. Instead, \c
- BirthdayParty could be a separate component with a property \c rsvp.
- \code
- GraduationParty {
- Boy { BirthdayParty.rsvp: "2009-06-01" }
- }
- \endcode
-
- From C++, including the attaching type implementation, the attachment object
- for an instance can be accessed using the following method:
-
- \code
- template<typename T>
- QObject *qmlAttachedPropertiesObject<T>(QObject *attachee, bool create = true);
- \endcode
-
- This returns the attachment object attached to \a attachee by the attaching
- type \a T. If type \a T is not a valid attaching type, this method always
- returns 0. If \a create is true, a valid attachment object will always be
- returned, creating it if it does not already exist. If \a create is false,
- the attachment object will only be returned if it has previously been
- created.
-
- The \c rsvp properties of each guest in the \c Birthday party is accessible
- through the \c qmlAttachedPropertiesObject function.
-
- \snippet examples/declarative/cppextensions/referenceexamples/attached/main.cpp query rsvp
-
- The
- \l {Extending QML - Attached Properties Example}{Attached Properties Example}
- demonstrates the creation of attached properties with a birthday party
- scenario.
-
-\section2 Object and List Properties
-
- QML can set properties of types that are more complex than basic intrinsics like
- integers and strings. Properties can also be object pointers, Qt interface
- pointers, lists of object pointers, and lists of Qt interface pointers. As QML
- is typesafe it ensures that only valid types are assigned to these properties,
- just like it does for primitive types.
-
- Properties that are pointers to objects or Qt interfaces are declared with the
- Q_PROPERTY() macro, just like other properties. The \c host property
- declaration looks like this:
-
- \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 1
-
- As long as the property type, in this case \c Person, is registered with QML the
- property can be assigned.
-
- QML also supports assigning Qt interfaces. To assign to a property whose type
- is a Qt interface pointer, the interface must also be registered with QML. As
- they cannot be instantiated directly, registering a Qt interface is different
- from registering a new QML type. The following function is used instead:
-
- \code
- template<typename T>
- int qmlRegisterInterface(const char *typeName)
- \endcode
-
- \c qmlRegisterInterface registers the C++ interface \a T with the QML system
- as \a typeName.
-
- Following registration, QML can coerce objects that implement this interface
- for assignment to appropriately typed properties.
-
-
- \snippet examples/declarative/cppextensions/referenceexamples/properties/example.qml 0
-
- The \c guests property is a \e{list property} of \c Person objects. A list
- of \c Person objects are bound to the \c BirthdayParty's \c host property,
- and assigns three \c Person objects to the guests property.
-
- Properties that are lists of objects or Qt interfaces are also declared with
- the Q_PROPERTY() macro. However, list properties must have the type
- \l{QQmlListProperty}{QQmlListProperty<T>}.
-
- \snippet examples/declarative/cppextensions/referenceexamples/properties/birthdayparty.h 2
-
- As with the other property types, the type of list content, \a T, must be
- \l{register-c++-type}{registered} into the runtime.
-
- \snippet examples/declarative/cppextensions/referenceexamples/properties/main.cpp register list
-
- \l {Extending QML - Object and List Property Types Example} shows the
- complete code used to create the \c BirthdayParty type. For more
- information, visit \l{QQmlListProperty}{QQmlListProperty<T>}
- for creating list properties.
-
-\section2 Sequence Types
-
- Certain C++ sequence types are supported transparently in QML as JavaScript
- Array types.
- In particular, QML currently supports:
- \list
- \li \c {QList<int>}
- \li \c {QList<qreal>}
- \li \c {QList<bool>}
- \li \c {QList<QString>} and \c{QStringList}
- \li \c {QList<QUrl>}
- \endlist
-
- These sequence types are implemented directly in terms of the underlying C++
- sequence. There are two ways in which such sequences can be exposed to QML:
- as a Q_PROPERTY of the given sequence type; or as the return type of a
- Q_INVOKABLE method. There are some differences in the way these are
- implemented, which are important to note.
-
- If the sequence is exposed as a Q_PROPERTY, accessing any value in the
- sequence by index will cause the sequence data to be read from the QObject's
- property, then a read to occur. Similarly, modifying any value in the
- sequence will cause the sequence data to be read, and then the modification
- will be performed and the modified sequence will be written back to the
- QObject's property.
-
- If the sequence is returned from a Q_INVOKABLE function, access and mutation
- is much cheaper, as no QObject property read or write occurs; instead, the
- C++ sequence data is accessed and modified directly.
-
- Other sequence types are not supported transparently, and instead an
- instance of any other sequence type will be passed between QML and C++ as an
- opaque QVariantList.
-
- \b {Important Note:} There are some minor differences between the
- semantics of such sequence Array types and default JavaScript Array types
- which result from the use of a C++ storage type in the implementation. In
- particular, deleting an element from an Array will result in a
- default-constructed value replacing that element, rather than an Undefined
- value. Similarly, setting the length property of the Array to a value larger
- than its current value will result in the Array being padded out to the
- specified length with default-constructed elements rather than Undefined
- elements. Finally, the Qt container classes support signed (rather than
- unsigned) integer indexes; thus, attempting to access any index greater
- than INT_MAX will fail.
-
- The default-constructed values for each sequence type are as follows:
- \table
- \row \li QList<int> \li integer value 0
- \row \li QList<qreal> \li real value 0.0
- \row \li QList<bool> \li boolean value \c {false}
- \row \li QList<QString> and QStringList \li empty QString
- \row \li QList<QUrl> \li empty QUrl
- \endtable
-
- If you wish to remove elements from a sequence rather than simply replace
- them with default constructed values, do not use the indexed delete operator
- ("delete sequence[i]") but instead use the \c {splice} function
- ("sequence.splice(startIndex, deleteCount)").
-
-
-\section2 Property Signals
-
- All properties on custom types automatically support property binding.
- However, for binding to work correctly, QML must be able to reliably
- determine when a property has changed so that it knows to reevaluate any
- bindings that depend on the property's value. QML relies on the presence of
- a \l {Qt's Property System}{NOTIFY signal} for this determination.
-
- Here is the \c host property declaration:
-
- \snippet examples/declarative/cppextensions/referenceexamples/binding/birthdayparty.h 0
-
- The NOTIFY attribute is followed by a signal name. It is the responsibility
- of the class implementer to ensure that whenever the property's value
- changes, the NOTIFY signal is emitted. The signature of the NOTIFY signal is
- not important to QML.
-
- To prevent loops or excessive evaluation, developers should ensure that the
- signal is only emitted whenever the property's value is actually changed. If
- a property, or group of properties, is infrequently used it is permitted to
- use the same NOTIFY signal for several properties. This should be done with
- care to ensure that performance doesn't suffer.
-
- To keep QML reliable, if a property does not have a NOTIFY signal, it cannot
- be used in a binding expression. However, the property can still be assigned
- a binding as QML does not need to monitor the property for change in that
- scenario.
-
- Consider a custom type, \c TestElement, that has two properties, \c a and
- \c b. Property \c a does \e not have a NOTIFY signal, and property \c b does
- have a NOTIFY signal.
-
- \code
- TestElement {
- // This is OK
- a: b
- }
- TestElement {
- // Will NOT work
- b: a
- }
- \endcode
-
- The presence of a NOTIFY signal does incur a small overhead. There are cases
- where a property's value is set at object construction time, and does not
- subsequently change. The most common case of this is when a type uses \l
- {Grouped Properties}, and the grouped property object is allocated once, and
- only freed when the object is deleted. In these cases, the CONSTANT
- attribute may be added to the property declaration instead of a NOTIFY
- signal.
-
- \snippet examples/declarative/cppextensions/referenceexamples/binding/person.h 0
-
- Extreme care must be taken here or applications using your type may misbehave.
- The CONSTANT attribute should only be used for properties whose value is set,
- and finalized, only in the class constructor. All other properties that want
- to be used in bindings should have a NOTIFY signal instead.
-
- \l {Extending QML - Binding Example} shows the BirthdayParty example updated to
- include NOTIFY signals for use in binding.
-
-\section1 Signals Support
-
- A \l{signals and slots}{signal} in Qt C++ is readily available as a
- \l{QML Signal and Handler Event System}{QML signal}. A signal will have
- a corresponding signal \e{handler}, created automatically. The handler
- name will have \c on prepended at the beginning of the name. The first
- character of the signal is uppercased for the signal handler. The
- signal parameter is also availabe to the QML signal.
-
- \snippet examples/declarative/cppextensions/referenceexamples/signal/birthdayparty.h 0
- The QML engine will create a handler for the \c partyStarted signal
- called \c onPartyStarted.
- \snippet examples/declarative/cppextensions/referenceexamples/signal/example.qml 0
-
- Classes may have multiple signals with the same name, but only the final
- signal is accessible as a QML signal. Note that signals with the same name
- but different parameters cannot be distinguished from one another.
-
- Signal parameters are exposed and can be any one of the QML
- \l{QML Basic Types}{basic types} as well registered object types. Accessing
- unregistered types will not generate an error, but the parameter value will
- not be accessible from the handler.
-
- To use signals from items not created in QML, access their signals with the
- \l {Connections} element.
-
- Additionally, if a property is added to a C++ class, all QML elements
- based on that C++ class will have a \e{value-changed} signal handler
- for that property. The name of the signal handler is
- \e{on<Property-name>Changed}, with the first letter of the property
- name being upper case.
-
- The \l {Extending QML - Signal Support Example}{Signal Support Example}
- shows an example application exposing signals to a QML component.
-
-\section1 Exposing Methods
-
- The Q_INVOKABLE macro exposes any Qt C++ method as a QML method.
-
- \snippet examples/declarative/cppextensions/referenceexamples/methods/birthdayparty.h 0
-
- In a QML file, we can invoke the method as we would a
- \l{JavaScript Expressions in QML}{JavaScript expression}.
- \snippet examples/declarative/cppextensions/referenceexamples/methods/example.qml 0
-
- \l {Extending QML - Methods Example}{Methods example} uses the Q_INVOKABLE
- method to expose methods and demonstrates some usages of the method in
- an application.
-
- An alternative to the Q_INVOKABLE macro is to declare the C++ method as a
- \l{signals and slot}{slot}.
-
- \code
- slots:
- void invite(const QString &name);
- \endcode
-
-\section1 Type Revisions and Versions
-
- Type revisions and versions allow new properties or methods to exist in the
- new version while remaining compatible with previous versions.
-
- Consider these two QML files:
- \code
- // main.qml
- import QtQuick 1.0
- Item {
- id: root
- MyComponent {}
- }
- \endcode
-
- \code
- // MyComponent.qml
- import MyModule 1.0
- CppItem {
- value: root.x
- }
- \endcode
- where \c CppItem maps to the C++ class \c QCppItem.
-
- If the author of QCppItem adds a \c root property to QCppItem in a new
- version of the module, \c root.x now resolves to a different value because
- \c root is also the \c id of the top level component. The author could
- specify that the new \c root property is available from a specific minor
- version. This permits new properties and features to be added to existing
- elements without breaking existing programs.
-
- The REVISION tag is used to mark the \c root property as added in revision 1
- of the class. Methods such as Q_INVOKABLE's, signals and slots can also be
- tagged for a revision using the \c Q_REVISION(x) macro:
-
- \code
- class CppElement : public BaseObject
- {
- Q_OBJECT
- Q_PROPERTY(int root READ root WRITE setRoot NOTIFY rootChanged REVISION 1)
-
- signals:
- Q_REVISION(1) void rootChanged();
- };
- \endcode
-
- To register the new class revision to a particular version the following function is used:
-
- \code
- template<typename T, int metaObjectRevision>
- int qmlRegisterType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
- \endcode
-
- To register \c CppElement version 1 for \c {MyModule 1.1}:
-
- \code
- qmlRegisterType<QCppElement,1>("MyModule", 1, 1, "CppElement")
- \endcode
-
- \c root is only available when MyModule 1.1 is imported.
-
- For the same reason, new elements introduced in later versions should use
- the minor version argument of qmlRegisterType.
-
- This feature of the language allows for behavioural changes to be made
- without breaking existing applications. Consequently QML module authors
- should always remember to document what changed between minor versions, and
- QML module users should check that their application still runs correctly
- before deploying an updated import statement.
-
- You may also register the revision of a base class that your module depends upon
- using the qmlRegisterRevision() function:
-
- \code
- template<typename T, int metaObjectRevision>
- int qmlRegisterRevision(const char *uri, int versionMajor, int versionMinor)
- \endcode
-
- For example, if \c BaseObject is changed and now has a revision 1, you can specify that
- your module uses the new revision:
-
- \code
- qmlRegisterRevision<BaseObject,1>("MyModule", 1, 1);
- \endcode
-
- This is useful when deriving from base classes not declared as part of your
- module, e.g. when extending classes from the QtQuick library.
-
- The revision feature of QML allows for behavioral changes without breaking
- existing applications. Consequently, QML module authors should always
- remember to document what changed between minor versions, and QML module
- users should check that their application still runs correctly before
- deploying an updated import statement.
-
-\target qml-c++-coercion
-\section1 Inheritance and Coercion
-
- QML supports C++ inheritance hierarchies and can freely coerce between
- known, valid object types. This enables the creation of common base classes
- that allow the assignment of specialized classes to object or list
- properties.
-
- \snippet examples/declarative/cppextensions/referenceexamples/coercion/example.qml 0
-
- The QML snippet shown above assigns a \c Boy object to the \c
- BirthdayParty's \c host property, and assigns three other objects to the \c
- guests property. Both the \c host and the \c guests properties binds to the
- \c Person type, but the assignment is valid as both the \c Boy and \c Girl
- objects inherit from \c Person.
-
- To assign to a property, the property's type must have been
- \l{register-c++-type}{registered} to the \l{The QML Engine}{declarative
- runtime}. If a type that acts purely as a base class that cannot be
- instantiated from QML needs to be registered as well. The
- \l qmlRegisterType() is useful for this occasion.
-
- \code
- template<typename T>
- int qmlRegisterType()
- \endcode
-
- This function registers the C++ type \a T with the QML system. The
- parameterless call to the template function qmlRegisterType() does not
- define a mapping between the C++ class and a QML element name, so the type
- is not instantiable from QML, but it is available for type coercion.
-
- \snippet examples/declarative/cppextensions/referenceexamples/coercion/main.cpp 0
- \snippet examples/declarative/cppextensions/referenceexamples/coercion/main.cpp register boy girl
- The \c Person class is registered withouth the parameters. Both the
- \c Boy and \c Girl class derive from the \c Person class.
-
- Type \a T must inherit QObject, but there are no restrictions on whether it
- is concrete or the signature of its constructor.
-
- QML will automatically coerce C++ types when assigning to either an object
- property, or to a list property. Only if coercion fails does an assignment
- error occur.
-
- The \l{Extending QML - Inheritance and Coercion Example}{Inheritance and Coercion Example}
- shows the complete code used to create the \c Boy and \c Girl types.
-
-\target qml-c++-extension
-\section1 Extension Objects
-
- \snippet examples/declarative/cppextensions/referenceexamples/extended/example.qml 0
-
- The \c leftMargin property is a new property to an existing C++ type,
- \l QLineEdit, without modifying its source code.
-
- When integrating existing classes and technology into QML, APIs will
- often need tweaking to fit better into the declarative environment.
- Although the best results are usually obtained by modifying the original
- classes directly, if this is either not possible or is complicated by some
- other concerns, extension objects allow limited extension possibilities
- without direct modifications.
-
- \e{Extension objects} add additional properties to an existing type.
- Extension objects can only add properties, not signals or methods. An
- extended type definition allows the programmer to supply an additional type,
- known as the \e{extension type}, when registering the class. The
- properties are transparently merged with the original target class when used
- from within QML.
-
- The \l qmlRegisterExtendedType() is for registering extended types. Note
- that it has two forms.
- \code
- template<typename T, typename ExtendedT>
- int qmlRegisterExtendedType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
-
- template<typename T, typename ExtendedT>
- int qmlRegisterExtendedType()
- \endcode
- functions should be used instead of the regular \c qmlRegisterType() variations.
- The arguments are identical to the corresponding non-extension registration functions,
- except for the ExtendedT parameter which is the type
- of the extension object.
-
- An extension class is a regular QObject, with a constructor that takes a
- QObject pointer. However, the extension class creation is delayed until the
- first extended property is accessed. The extension class is created and the
- target object is passed in as the parent. When the property on the original
- is accessed, the corresponding property on the extension object is used
- instead.
-
- The \l{Extending QML - Extension Objects}{Extension Objects} example
- demonstrates a usage of extension objects.
-
-\section1 Property Value Sources
-
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/example.qml 0
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/example.qml 1
-
-The QML snippet shown above applies a property value source to the \c announcement property.
-A property value source generates a value for a property that changes over time.
-
-Property value sources are most commonly used to do animation. Rather than
-constructing an animation object and manually setting the animation's "target"
-property, a property value source can be assigned directly to a property of any
-type and automatically set up this association.
-
-The example shown here is rather contrived: the \c announcement property of the
-\c BirthdayParty object is a string that is printed every time it is assigned and
-the \c HappyBirthdaySong value source generates the lyrics of the song
-"Happy Birthday".
-
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/birthdayparty.h 0
-
-Normally, assigning an object to a string property would not be allowed. In
-the case of a property value source, rather than assigning the object instance
-itself, the QML engine sets up an association between the value source and
-the property.
-
-Property value sources are special types that derive from the
-QQmlPropertyValueSource base class. This base class contains a single method,
-QQmlPropertyValueSource::setTarget(), that the QML engine invokes when
-associating the property value source with a property. The relevant part of
-the \c HappyBirthdaySong type declaration looks like this:
-
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 0
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 1
-\snippet examples/declarative/cppextensions/referenceexamples/valuesource/happybirthdaysong.h 2
-
-In all other respects, property value sources are regular QML types. They must
-be registered with the QML engine using the same macros as other types, and can
-contain properties, signals and methods just like other types.
-
-When a property value source object is assigned to a property, QML first tries
-to assign it normally, as though it were a regular QML type. Only if this
-assignment fails does the engine call the \l {QQmlPropertyValueSource::}{setTarget()} method. This allows
-the type to also be used in contexts other than just as a value source.
-
-\l {Extending QML - Property Value Source Example} shows the complete code used
-to implement the \c HappyBirthdaySong property value source.
-
-\section1 Optimization and Other Considerations
-
-The \l{qml-engine-optimization}{ QML Engine} article suggests possible
-optimization considerations as memory management and QVariant type usages.
-
-*/
snippets
imagedirs += images
+
+#add qml sources because of dependencies
+headerdirs += ../../qml
+sourcedirs += ../../qml
+exampledirs += ../../qml/snippets \
+ ../../qml
+
+imagedirs += ../../qml
dynamic applications.
For App Developers and Designers, who want to deliver apps with amazing user
-experience, Qt provides the QML language, the Qt Quick Elements, and tools in Qt
+experience, Qt provides the QML language, the Qt Quick types, and tools in Qt
Creator that make it faster than ever to transform your brilliant idea into a
winning App across mobile, embedded, and desktop platforms.
\target qtquick-overviews
-\div {class="threecolumn_area"}
- \div {class="heading"}
- QML Topics
- \enddiv
- QML is a declarative language for creating flexible and reusable
- components. The QML runtime powers QML based applications. The runtime
- includes a QML engine, JavaScript engine, and mechanism to bind to the Qt
- Framework.
-
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- QML Essentials
- \enddiv
- \list
- \li \l{QML Components}{Components}
- \li \l{Properties and Property Binding in QML}{Properties and Property Binding}
- \li \l{JavaScript Expressions in QML}{JavaScript Code}
- \li \l{QML Signal and Handler Event System}{Signal and Handler Event System}
- \li \l{QML Modules}{Modules}
- \endlist
- \list
- \li \l{What's New in Qt Quick 2}{What's New in Qt Quick}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- QML Engine
- \enddiv
- \list
- \li \l{The QML Engine}
- \li \l{QML Global Object}
- \li \l{Dynamic Object Management in QML}{Dynamic Object Management}
- \li \l{QML Performance}{Performance}
- \endlist
- \enddiv
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- Reference
- \enddiv
- \list
- \li \l{QML Syntax}
- \li \l{QML Basic Types}{Data Types}
- \li \l{QML Coding Conventions}{Coding Conventions}
- \li \l{QML Security}{Security Model}
- \li \l{QML Scope}{Scope Model}
- \li \l{QML Documents}{Documents}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- QML Bindings with Qt C++
- \enddiv
- \list
- \li \l{Creating QML Types}
- \li \l{QML Plugins}
- \li \l{Exposing C++ Models}
- \li \l{Integrating QML Code with Existing Qt UI Code}{Qt Gui Porting Information}
- \endlist
- \enddiv
- \div {class=" threecolumn_piece"}
- \div {class="heading"}
- Tools
- \enddiv
- \list
- \li \l{QML Internationalization}{Internationalization}
- \li \l{QtQuickTest Reference Documentation}
- \li \l{Debugging QML}
- \endlist
- \enddiv
-\enddiv
-\div {class="threecolumn_area"}
- \div {class="heading"}
- Qt Quick Elements
- \enddiv
- Qt Quick Elements features graphical elements, user input system,
- animation system, and data visualization through models and delegates.
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Graphics and Special Effects
- \enddiv
- \list
- \li \l{Basic Elements}{Basic Elements}
- \li \l{Painting with Canvas API}
- \li \l{Using the Qt Quick Particle System}{Particle Effects}
- \li \l{Shader Effects in QML}{Shader Effects}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Anchoring and Layouts
- \enddiv
- \list
- \li \l{Item Layouts}
- \li \l{Layouts with Anchors}
- \li \l{Right-to-left User Interfaces}{Right-to-left User Interfaces}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Mouse and Keyboard Input
- \enddiv
- \list
- \li \l{Mouse Events}{Mouse Events}
- \li \l{Text Handling and Validators}{Text Handling and Validators}
- \li \l{Keyboard Focus in QML}{Keyboard Focus}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- States and Transitions
- \enddiv
- \list
- \li \l{States}
- \li \l{Animation and Transitions}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Data with Models and Views
- \enddiv
- \list
- \li \l{Models and Views}
- \endlist
- \enddiv
- \div {class="threecolumn_piece"}
- \div {class="heading"}
- Data Storage and Resources
- \enddiv
- \list
- \li \l{Local Storage}{SQL Local Storage}
- \endlist
- \enddiv
-\enddiv
+\section1 QML - the Declarative Language
+
+ QML is a declarative language for creating flexible and reusable types.
+ The QML runtime powers QML based applications. The runtime includes a QML
+ engine, JavaScript engine, and mechanism to bind to C++ types.
+
+ \list
+ \li \l{QML - the Declarative Language}{QML} - the declarative language
+ \endlist
+
+\section1 Qt Quick User Interfaces
+
+Qt Quick features QML visual types, user input system, animation system, and data visualization through models and delegates.
+
+ \list
+ \li \l{UI Creation with Qt Quick}
+ \endlist
+
+\section1 QML Engine
+There is a QML engine which runs QML applications. It includes C++ classes
+that loads and initializes QML code and a JavaScript engine for running
+expressions.
+ \list
+ \li \l{The QML Engine}
+ \li \l{Qt Declarative UI Runtime}{Declarative Runtime}
+ \endlist
+
+\section1 SQL Local Storage
+
+The SQL Local Storage provides a JavaScript interface to an SQLite database.
+To use, import the \c QtQuick.LocalStorage module into a namespace with the
+\c as keyword.
+
+\code
+import QtQuick.LocalStorage 2.0 as Sql
+\endcode
+
+The SQL Local Storage page has more information about the interface.
+\list
+ \li \l{Local Storage}{SQL Local Storage}
+\endlist
*/
/*!
\page qtquick-states.html
-\title States
+\title Qt Quick States
\brief Creating and setting states
\target qmlstates
--- /dev/null
+/****************************************************************************
+**
+** 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 qtquick-uicreation.html
+\title UI Creation with Qt Quick
+
+Qt Quick features graphical types, user input system, animation system, and data
+visualization through models and delegates.
+
+\section1 Import the QtQuick Types
+Qt Quick module contains several submodules which implement application user
+interfaces.
+
+\list
+\li QtQuick - provides the visual types necessary for building dynamic user interfaces
+\li QtQuick.Particles - a particle system for creating special effects
+\li QtQuick.XmlListModel - for constructing a model from an XML data source
+\endlist
+
+To use the types in the modules, import the modules.
+\code
+import QtQuick 2.0
+import QtQuick.Particles 2.0
+import QtQuick.XmlListModel 2.0
+\endcode
+
+\section1 Graphics and Special Effects
+ \list
+ \li \l{Basic Elements}{Basic Elements}
+ \li \l{Painting with Canvas API}
+ \li \l{Using the Qt Quick Particle System}{Particle Effects}
+ \li \l{Shader Effects in QML}{Shader Effects}
+ \endlist
+
+\section1 Anchoring and Layouts
+ \list
+ \li \l{Item Layouts}
+ \li \l{Layouts with Anchors}
+ \li \l{Right-to-left User Interfaces}{Right-to-left User Interfaces}
+ \endlist
+
+\section1 Mouse and Keyboard Input
+
+ \list
+ \li \l{Mouse Events}{Mouse Events}
+ \li \l{Text Handling and Validators}{Text Handling and Validators}
+ \li \l{Keyboard Focus in QML}{Keyboard Focus}
+ \endlist
+
+\section1 States and Transitions
+
+ \list
+ \li \l{Qt Quick States}{States}
+ \li \l{Animation and Transitions}
+ \endlist
+
+\section1 Data with Models and Views
+
+\list
+\li \l{Models and Views}
+\endlist
+
+*/
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