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42 #include "qdeclarativeextensionplugin.h"
48 \class QDeclarativeExtensionPlugin
49 \brief The QDeclarativeExtensionPlugin class provides an abstract base for custom QML extension plugins.
53 QDeclarativeExtensionPlugin is a plugin interface that makes it possible to
54 create QML extensions that can be loaded dynamically into QML applications.
55 These extensions allow custom QML types to be made available to the QML engine.
57 To write a QML extension plugin:
60 \o Subclass QDeclarativeExtensionPlugin, implement registerTypes() method
61 to register types using qmlRegisterType(), and export the class using the Q_EXPORT_PLUGIN2() macro
62 \o Write an appropriate project file for the plugin
63 \o Create a \l{Writing a qmldir file}{qmldir file} to describe the plugin
66 QML extension plugins can be used to provide either application-specific or
67 library-like plugins. Library plugins should limit themselves to registering types,
68 as any manipulation of the engine's root context may cause conflicts
69 or other issues in the library user's code.
74 Suppose there is a new \c TimeModel C++ class that should be made available
75 as a new QML element. It provides the current time through \c hour and \c minute
76 properties, like this:
78 \snippet examples/declarative/cppextensions/plugins/plugin.cpp 0
81 To make this class available as a QML type, create a plugin that registers
82 this type with a specific \l {QML Modules}{module} using qmlRegisterType(). For this example the plugin
83 module will be named \c com.nokia.TimeExample (as defined in the project
86 \snippet examples/declarative/cppextensions/plugins/plugin.cpp plugin
88 \snippet examples/declarative/cppextensions/plugins/plugin.cpp export
90 This registers the \c TimeModel class with the 1.0 version of this
91 plugin library, as a QML type called \c Time. The Q_ASSERT statement
92 ensures the module is imported correctly by any QML components that use this plugin.
94 The project file defines the project as a plugin library and specifies
95 it should be built into the \c com/nokia/TimeExample directory:
102 DESTDIR = com/nokia/TimeExample
103 TARGET = qmlqtimeexampleplugin
107 Finally, a \l{Writing a qmldir file}{qmldir file} is required in the \c com/nokia/TimeExample directory
108 that describes the plugin. This directory includes a \c Clock.qml file that
109 should be bundled with the plugin, so it needs to be specified in the \c qmldir
112 \quotefile examples/declarative/cppextensions/plugins/com/nokia/TimeExample/qmldir
114 Once the project is built and installed, the new \c Time element can be
115 used by any QML component that imports the \c com.nokia.TimeExample module:
117 \snippet examples/declarative/cppextensions/plugins/plugins.qml 0
119 The full source code is available in the \l {declarative/cppextensions/plugins}{plugins example}.
121 The \l {Tutorial: Writing QML extensions with C++} also contains a chapter
122 on creating QML plugins.
124 \sa QDeclarativeEngine::importPlugin(), {How to Create Qt Plugins}
128 \fn void QDeclarativeExtensionPlugin::registerTypes(const char *uri)
130 Registers the QML types in the given \a uri. Subclasses should implement
131 this to call qmlRegisterType() for all types which are provided by the extension
134 The \a uri is an identifier for the plugin generated by the QML engine
135 based on the name and path of the extension's plugin library.
139 Constructs a QML extension plugin with the given \a parent.
141 Note that this constructor is invoked automatically by the
142 Q_EXPORT_PLUGIN2() macro, so there is no need for calling it
145 QDeclarativeExtensionPlugin::QDeclarativeExtensionPlugin(QObject *parent)
153 QDeclarativeExtensionPlugin::~QDeclarativeExtensionPlugin()
158 \fn void QDeclarativeExtensionPlugin::initializeEngine(QDeclarativeEngine *engine, const char *uri)
160 Initializes the extension from the \a uri using the \a engine. Here an application
161 plugin might, for example, expose some data or objects to QML,
162 as context properties on the engine's root context.
165 void QDeclarativeExtensionPlugin::initializeEngine(QDeclarativeEngine *engine, const char *uri)