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diff --git a/doc/src/examples/qml-folderlistmodel.qdoc b/doc/src/examples/qml-folderlistmodel.qdoc new file mode 100644 index 0000000..b820528 --- /dev/null +++ b/doc/src/examples/qml-folderlistmodel.qdoc @@ -0,0 +1,144 @@ +/**************************************************************************** +** +** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (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 Technology Preview License Agreement accompanying +** this package. +** +** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + +\title FolderListModel - a C++ model plugin +\example src/imports/folderlistmodel + +This plugin shows how to make a C++ model available to QML. It presents +a simple file list for a single folder (directory) and allows the presented +folder to be changed. + +\image declarative-folderlistmodel.png The FolderListModel used to choose a QML file + +We do not explain the model implementation in detail, but rather focus on the mechanics of +making the model available to QML. + +\section1 Usage from QML + +The type we are creating can be used from QML like this: + +\snippet doc/src/snippets/declarative/folderlistmodel.qml 0 + +\section1 Defining the Model + +We are subclassing QAbstractListModel which will allow us to give data to QML and +send notifications when the data changes: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h class begin + +As you see, we also inherit the QDeclarativeParserStatus interface, so that we +can delay initial processing until we have all properties set (via componentComplete() below). + +The first thing to do when devising a new type for QML is to define the properties +you want the type to have: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h class props + +The purposes of each of these should be pretty obvious - in QML we will set the folder +to display (a file: URL), and the kinds of files we want to show in the view of the model. + +Next are the constructor, destructor, and standard QAbstractListModel subclassing requirements: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h abslistmodel + +The data() function is where we provide model values. The rowCount() function +is also a standard part of the QAbstractListModel interface, but we also want to provide +a simpler count property: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h count + +Then we have the functions for the remaining properties which we defined above: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h prop funcs + +Imperative actions upon the model are made available to QML via a Q_INVOKABLE tag on +a normal member function. The isFolder(index) function says whether the value at \e index +is a folder: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h isfolder + +Then we have the QDeclarativeParserStatus interface: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h parserstatus + +Then the NOTIFY function for the folders property. The implementation will emit this +when the folder property is changed. + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h notifier + +The class ends with some implementation details: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h class end + +Lastly, the boilerplare to declare the type for QML use: + +\snippet src/imports/folderlistmodel/qdeclarativefolderlistmodel.h qml decl + +\section1 Connecting the Model to QML + +To make this class available to QML, we only need to make a simple subclass of QDeclarativeExtensionPlugin: + +\snippet src/imports/folderlistmodel/plugin.cpp class decl + +and then use the standard Qt plugin export macro: + +\snippet src/imports/folderlistmodel/plugin.cpp plugin export decl + +Finally, in order for QML to connect the "import" statement to our plugin, we list it in the qmldir file: + +\l{src/imports/folderlistmodel/qmldir} + +This qmldir file and the compiled plugin will be installed in \c $QTDIR/imports/Qt/labs/folderlistmodel/ where +the QML engine will find it (since \c $QTDIR/imports is the value of QLibraryInf::libraryPath()). + +\section1 Implementing the Model + +We'll not discuss the model implementation in detail, as it is not specific to QML - any Qt C++ model +can be interfaced to QML. +This implementation is basically just takes the krufty old QDirModel, +which is a tree with lots of detailed roles and re-presents it as a simpler list model where +each item is just a fileName and a filePath (as a file: URL rather than a plain file, since QML +works with URLs for all content). + +\l{src/imports/folderlistmodel/qdeclarativefolderlistmodel.cpp} +*/ |