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diff --git a/doc/src/declarative/integrating.qdoc b/doc/src/declarative/integrating.qdoc new file mode 100644 index 0000000..d93a6ff --- /dev/null +++ b/doc/src/declarative/integrating.qdoc @@ -0,0 +1,104 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! +\page qml-integration.html +\title Integrating QML with existing Qt UI code + +If you have existing Qt UI code which does not use QML you can still +add QML to your UI, without having to rewrite it. + +\section1 Adding QML to a \l{QWidget} based UI +If you have an existing QWidget based UI you can simply write new custom +widgets in QML. To integrate them into your application you can create a +QmlView widget, and load the QML file into that. You'll then have a new widget +containing your declarative UI, and you can interact with it through the +QmlView interface. The one drawback of this approach is that QmlView is a lot +heavier than a QWidget in terms of memory consumption and initialization speed, +and so having large numbers of them may lead to performance degredation. + +For a smooth transition from a QWidget based UI to a QML based UI, simply +rewrite your widgets in QML one at a time, using the above method. When +all of your widgets are written in QML you can rewrite your main widget in +QML, so as to load the other widgets in QML instead of using QmlViews. Then +you just load the main QML file on startup. + +Keep in mind that QWidgets were designed for different sorts of UIs than QML +was, and so it is not always a good idea to switch. QWidgets are a better +choice if your UI is comprised of a small number of complex and static +elements, and QML is a better choice if your UI is comprised of a large number +of simple and dynamic elements. + +\section1 Adding QML to a QGraphicsView based UI +If you have an existing Graphics View based UI you can create new items in QML, +and use \l{QmlComponent} to create \l{QGraphicsObject}s from the QML files. These +\l{QGraphicsObject}s can then be placed into your \l{QGraphicsScene} using \l{QGraphicsScene::addItem} +or by reparenting them to an item already in the \l{QGraphicsScene}. + +Example, for local QML files: + +\code +QGraphicsScene* scene = new QGraphicsScene; +QmlEngine *engine = new QmlEngine; +QmlComponent component(engine, QUrl::fromLocalFile(filename)); +QGraphicsObject *object = + qobject_cast<QGraphicsObject *>(component.create()); +scene->addItem(object); +\endcode + +\section1 Using existing QGraphicsWidgets in QML +Another way of integrating with a QGraphicsView based UI is to expose your +existing QGraphicsWidgets to QML, and constructing your scene in QML. Note that +this approach will not work with QGraphicsItems which are not QGraphicsWidgets, +and that this approach allows you to integrate new items written in QML +without using the above method. + +You can make custom C++ types +available in QML using the pair of macros listed in \l{Extending QML}. +While this is normally only useful for +types that were designed for QML use, in conjunction with the +\l{GraphicsObjectContainer} element QGraphicsWidget subclasses can also be +used effectively (if they were designed, like QGraphicsWidget, to be controllable through Qt's property system). +This way you can write your UI using QML, without having to rewrite your existing items. + +For details on implementing this approach see \l{Extending QML} page for details on exposing your C++ types, +and the \l{GraphicsObjectContainer} documentation for details about using it to wrap QGraphicsWidgets. +*/ |