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41
42 #include "qdeclarativeextensionplugin.h"
43
44 QT_BEGIN_NAMESPACE
45
46 /*!
47 \since 4.7
48 \class QDeclarativeExtensionPlugin
49 \brief The QDeclarativeExtensionPlugin class provides an abstract base for custom QML extension plugins.
50
51 \ingroup plugins
52
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.
56
57 To write a QML extension plugin:
58
59 \list
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
64 \endlist
65
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.
70
71
72 \section1 An example
73
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:
77
78 \snippet examples/declarative/cppextensions/plugins/plugin.cpp 0
79 \dots
80
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
84 file further below).
85
86 \snippet examples/declarative/cppextensions/plugins/plugin.cpp plugin
87 \codeline
88 \snippet examples/declarative/cppextensions/plugins/plugin.cpp export
89
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.
93
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:
96
97 \code
98 TEMPLATE = lib
99 CONFIG += qt plugin
100 QT += declarative
101
102 DESTDIR = com/nokia/TimeExample
103 TARGET = qmlqtimeexampleplugin
104 ...
105 \endcode
106
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
110 file:
111
112 \quotefile examples/declarative/cppextensions/plugins/com/nokia/TimeExample/qmldir
113
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:
116
117 \snippet examples/declarative/cppextensions/plugins/plugins.qml 0
118
119 The full source code is available in the \l {declarative/cppextensions/plugins}{plugins example}.
120
121 The \l {Tutorial: Writing QML extensions with C++} also contains a chapter
122 on creating QML plugins.
123
124 \sa QDeclarativeEngine::importPlugin(), {How to Create Qt Plugins}
125 */
126
127 /*!
128 \fn void QDeclarativeExtensionPlugin::registerTypes(const char *uri)
129
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
132 plugin.
133
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.
136 */
137
138 /*!
139 Constructs a QML extension plugin with the given \a parent.
140
141 Note that this constructor is invoked automatically by the
142 Q_EXPORT_PLUGIN2() macro, so there is no need for calling it
143 explicitly.
144 */
QDeclarativeExtensionPlugin(QObject * parent)145 QDeclarativeExtensionPlugin::QDeclarativeExtensionPlugin(QObject *parent)
146 : QObject(parent)
147 {
148 }
149
150 /*!
151 \internal
152 */
~QDeclarativeExtensionPlugin()153 QDeclarativeExtensionPlugin::~QDeclarativeExtensionPlugin()
154 {
155 }
156
157 /*!
158 \fn void QDeclarativeExtensionPlugin::initializeEngine(QDeclarativeEngine *engine, const char *uri)
159
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.
163 */
164
initializeEngine(QDeclarativeEngine * engine,const char * uri)165 void QDeclarativeExtensionPlugin::initializeEngine(QDeclarativeEngine *engine, const char *uri)
166 {
167 Q_UNUSED(engine);
168 Q_UNUSED(uri);
169 }
170
171 QT_END_NAMESPACE
172