1 /****************************************************************************
3 ** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
4 ** Contact: http://www.qt-project.org/legal
6 ** This file is part of the QtQml module of the Qt Toolkit.
8 ** $QT_BEGIN_LICENSE:LGPL$
9 ** Commercial License Usage
10 ** Licensees holding valid commercial Qt licenses may use this file in
11 ** accordance with the commercial license agreement provided with the
12 ** Software or, alternatively, in accordance with the terms contained in
13 ** a written agreement between you and Digia. For licensing terms and
14 ** conditions see http://qt.digia.com/licensing. For further information
15 ** use the contact form at http://qt.digia.com/contact-us.
17 ** GNU Lesser General Public License Usage
18 ** Alternatively, this file may be used under the terms of the GNU Lesser
19 ** General Public License version 2.1 as published by the Free Software
20 ** Foundation and appearing in the file LICENSE.LGPL included in the
21 ** packaging of this file. Please review the following information to
22 ** ensure the GNU Lesser General Public License version 2.1 requirements
23 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
25 ** In addition, as a special exception, Digia gives you certain additional
26 ** rights. These rights are described in the Digia Qt LGPL Exception
27 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
29 ** GNU General Public License Usage
30 ** Alternatively, this file may be used under the terms of the GNU
31 ** General Public License version 3.0 as published by the Free Software
32 ** Foundation and appearing in the file LICENSE.GPL included in the
33 ** packaging of this file. Please review the following information to
34 ** ensure the GNU General Public License version 3.0 requirements will be
35 ** met: http://www.gnu.org/copyleft/gpl.html.
40 ****************************************************************************/
42 #include "qqmlextensionplugin.h"
49 \class QQmlExtensionPlugin
50 \brief The QQmlExtensionPlugin class provides an abstract base for custom QML extension plugins.
54 QQmlExtensionPlugin is a plugin interface that makes it possible to
55 create QML extensions that can be loaded dynamically into QML applications.
56 These extensions allow custom QML types to be made available to the QML engine.
58 To write a QML extension plugin:
61 \li Subclass QQmlExtensionPlugin, implement registerTypes() method
62 to register types using qmlRegisterType(), and export the class using the Q_EXPORT_PLUGIN2() macro
63 \li Write an appropriate project file for the plugin
64 \li Create a \l{Module Definition qmldir Files}{qmldir file} to describe the plugin
67 QML extension plugins can be used to provide either application-specific or
68 library-like plugins. Library plugins should limit themselves to registering types,
69 as any manipulation of the engine's root context may cause conflicts
70 or other issues in the library user's code.
75 Suppose there is a new \c TimeModel C++ class that should be made available
76 as a new QML element. It provides the current time through \c hour and \c minute
77 properties, like this:
79 \snippet examples/qml/plugins/plugin.cpp 0
82 To make this class available as a QML type, create a plugin that registers
83 this type with a specific \l {QML Modules}{module} using qmlRegisterType(). For this example the plugin
84 module will be named \c TimeExample (as defined in the project
87 \snippet examples/qml/plugins/plugin.cpp plugin
89 \snippet examples/qml/plugins/plugin.cpp export
91 This registers the \c TimeModel class with the 1.0 version of this
92 plugin library, as a QML type called \c Time. The Q_ASSERT statement
93 ensures the module is imported correctly by any QML components that use this plugin.
95 The project file defines the project as a plugin library and specifies
96 it should be built into the \c imports/TimeExample directory:
103 DESTDIR = imports/TimeExample
104 TARGET = qmlqtimeexampleplugin
108 Finally, a \l{Module Definition qmldir Files}{qmldir file} is required in the \c imports/TimeExample directory
109 that describes the plugin. This directory includes a \c Clock.qml file that
110 should be bundled with the plugin, so it needs to be specified in the \c qmldir
113 \quotefile examples/qml/plugins/imports/TimeExample/qmldir
115 Once the project is built and installed, the new \c Time element can be
116 used by any QML component that imports the \c TimeExample module:
118 \snippet examples/qml/plugins/plugins.qml 0
120 The full source code is available in the \l {qml/plugins}{plugins example}.
122 The \l {Writing QML Extensions with C++} tutorial also contains a chapter
123 on creating QML plugins.
125 Note that the QtQuick 1 version is called QDeclarativeExtensionPlugin.
127 \sa QQmlEngine::importPlugin(), {How to Create Qt Plugins}
131 \fn void QQmlExtensionPlugin::registerTypes(const char *uri)
133 Registers the QML types in the given \a uri. Subclasses should implement
134 this to call qmlRegisterType() for all types which are provided by the extension
137 The \a uri is an identifier for the plugin generated by the QML engine
138 based on the name and path of the extension's plugin library.
142 Constructs a QML extension plugin with the given \a parent.
144 Note that this constructor is invoked automatically by the
145 Q_EXPORT_PLUGIN2() macro, so there is no need for calling it
148 QQmlExtensionPlugin::QQmlExtensionPlugin(QObject *parent)
156 QQmlExtensionPlugin::~QQmlExtensionPlugin()
161 \fn void QQmlExtensionPlugin::initializeEngine(QQmlEngine *engine, const char *uri)
163 Initializes the extension from the \a uri using the \a engine. Here an application
164 plugin might, for example, expose some data or objects to QML,
165 as context properties on the engine's root context.
168 void QQmlExtensionPlugin::initializeEngine(QQmlEngine *engine, const char *uri)