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<td width="1"> </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="functions.html"><font color="#004faf">All Functions</font></a> · <a href="overviews.html"><font color="#004faf">Overviews</font></a></td></tr></table><h1 class="title">Tree Model Completer Example<br /><span class="subtitle"></span>
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<p>Files:</p>
<ul>
<li><a href="tools-treemodelcompleter-mainwindow-cpp.html">tools/treemodelcompleter/mainwindow.cpp</a></li>
<li><a href="tools-treemodelcompleter-mainwindow-h.html">tools/treemodelcompleter/mainwindow.h</a></li>
<li><a href="tools-treemodelcompleter-treemodelcompleter-cpp.html">tools/treemodelcompleter/treemodelcompleter.cpp</a></li>
<li><a href="tools-treemodelcompleter-treemodelcompleter-h.html">tools/treemodelcompleter/treemodelcompleter.h</a></li>
<li><a href="tools-treemodelcompleter-main-cpp.html">tools/treemodelcompleter/main.cpp</a></li>
<li><a href="tools-treemodelcompleter-treemodelcompleter-pro.html">tools/treemodelcompleter/treemodelcompleter.pro</a></li>
<li><a href="tools-treemodelcompleter-treemodelcompleter-qrc.html">tools/treemodelcompleter/treemodelcompleter.qrc</a></li>
</ul>
<p>The Tree Model Completer example shows how to provide completion facilities for a hierarchical model, using a period as the separator to access Child, GrandChild and GrandGrandChild level objects.</p>
<p align="center"><img src="images/treemodelcompleter-example.png" /></p><p>Similar to the <a href="tools-completer.html">Completer Example</a>, we provide <a href="qcombobox.html">QComboBox</a> objects to enable selection for completion mode and case sensitivity, as well as a <a href="qcheckbox.html">QCheckBox</a> for wrap completions.</p>
<a name="the-resource-file"></a>
<h2>The Resource File</h2>
<p>The contents of the TreeModelCompleter is read from <i>treemodel.txt</i>. This file is embedded within the <i>treemodelcompleter.qrc</i> resource file, which contains the following:</p>
<pre> <!DOCTYPE RCC><RCC version="1.0">
<qresource prefix="/">
<file>resources/treemodel.txt</file>
</qresource>
</RCC></pre>
<a name="treemodelcompleter-class-definition"></a>
<h2>TreeModelCompleter Class Definition</h2>
<p>The <tt>TreeModelCompleter</tt> is a subclass of <a href="qcompleter.html">QCompleter</a> with two constructors - one with <i>parent</i> as an argument and another with <i>parent</i> and <i>model</i> as arguments.</p>
<pre> class TreeModelCompleter : public QCompleter
{
Q_OBJECT
Q_PROPERTY(QString separator READ separator WRITE setSeparator)
public:
TreeModelCompleter(QObject *parent = 0);
TreeModelCompleter(QAbstractItemModel *model, QObject *parent = 0);
QString separator() const;
public slots:
void setSeparator(const QString &separator);
protected:
QStringList splitPath(const QString &path) const;
QString pathFromIndex(const QModelIndex &index) const;
private:
QString sep;
};</pre>
<p>The class reimplements the protected functions <a href="qcompleter.html#splitPath">splitPath()</a> and <a href="qcompleter.html#pathFromIndex">pathFromIndex()</a> to suit a tree model. For more information on customizing <a href="qcompleter.html">QCompleter</a> to suit tree models, refer to <a href="qcompleter.html#handling-tree-models">Handling Tree Models</a>.</p>
<p><tt>TreeModelCompleter</tt> also has a separator property which is declared using the <a href="qobject.html#Q_PROPERTY">Q_PROPERTY</a>() macro. The separator has READ and WRITE attributes and the corresponding functions <tt>separator()</tt> and <tt>setSeparator()</tt>. For more information on <a href="qobject.html#Q_PROPERTY">Q_PROPERTY</a>(), refer to <a href="properties.html">Qt's Property System</a>.</p>
<a name="treemodelcompleter-class-implementation"></a>
<h2>TreeModelCompleter Class Implementation</h2>
<p>The first constructor constructs a <tt>TreeModelCompleter</tt> object with a parent while the second constructor constructs an object with a parent and a <a href="qabstractitemmodel.html">QAbstractItemModel</a>, <i>model</i>.</p>
<pre> TreeModelCompleter::TreeModelCompleter(QObject *parent)
: QCompleter(parent)
{
}
TreeModelCompleter::TreeModelCompleter(QAbstractItemModel *model, QObject *parent)
: QCompleter(model, parent)
{
}</pre>
<p>The <tt>separator()</tt> function is a getter function that returns the separator string.</p>
<pre> QString TreeModelCompleter::separator() const
{
return sep;
}</pre>
<p>As mentioned earlier, the <tt>splitPath()</tt> function is reimplemented because the default implementation is more suited to <a href="qdirmodel.html">QDirModel</a> or list models. In order for <a href="qcompleter.html">QCompleter</a> to split the path into a list of strings that are matched at each level, we split it using <a href="qstring.html#split">QString::split</a>() with <tt>sep</tt> as its separator.</p>
<pre> QStringList TreeModelCompleter::splitPath(const QString &path) const
{
if (sep.isNull()) {
return QCompleter::splitPath(path);
}
return path.split(sep);
}</pre>
<p>The <tt>pathFromIndex()</tt> function returns data for the completionRole() for a tree model. This function is reimplemented as its default implementation is more suitable for list models. If there is no separator, we use <a href="qcompleter.html">QCompleter</a>'s default implementation, otherwise we use the <a href="qlist.html#prepend">prepend()</a> function to navigate upwards and accumulate the data. The function then returns a <a href="qstringlist.html">QStringList</a>, <tt>dataList</tt>, using a separator to join objects of different levels.</p>
<pre> QString TreeModelCompleter::pathFromIndex(const QModelIndex &index) const
{
if (sep.isNull()) {
return QCompleter::pathFromIndex(index);
}
<span class="comment">// navigate up and accumulate data</span>
QStringList dataList;
for (QModelIndex i = index; i.isValid(); i = i.parent()) {
dataList.prepend(model()->data(i, completionRole()).toString());
}
return dataList.join(sep);
}</pre>
<a name="mainwindow-class-definition"></a>
<h2>MainWindow Class Definition</h2>
<p>The <tt>MainWindow</tt> class is a subclass of <a href="qmainwindow.html">QMainWindow</a> and implements five custom slots: <tt>about()</tt>, <tt>changeCase()</tt>, <tt>changeMode()</tt>, <tt>highlight()</tt>, and <tt>updateContentsLabel()</tt>.</p>
<pre> class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
private slots:
void about();
void changeCase(int);
void changeMode(int);
void highlight(const QModelIndex&);
void updateContentsLabel(const QString&);</pre>
<p>In addition, the class has two private functions, <tt>createMenu()</tt> and <tt>modelFromFile()</tt>, as well as private instances of <a href="qtreeview.html">QTreeView</a>, <a href="qcombobox.html">QComboBox</a>, <a href="qlabel.html">QLabel</a>, <tt>TreeModelCompleter</tt> and <a href="qlineedit.html">QLineEdit</a>.</p>
<pre> private:
void createMenu();
QAbstractItemModel *modelFromFile(const QString& fileName);
QTreeView *treeView;
QComboBox *caseCombo;
QComboBox *modeCombo;
QLabel *contentsLabel;
TreeModelCompleter *completer;
QLineEdit *lineEdit;
};</pre>
<a name="mainwindow-class-implementation"></a>
<h2>MainWindow Class Implementation</h2>
<p>The <tt>MainWindow</tt>'s constructor creates a <tt>MainWindow</tt> object with a parent and initializes the <tt>completer</tt> and <tt>lineEdit</tt>. The <tt>createMenu()</tt> function is invoked to set up the "File" menu and "Help" menu. The <tt>completer</tt>'s model is set to the <a href="qabstractitemmodel.html">QAbstractItemModel</a> obtained from <tt>modelFromFile()</tt>, and the <a href="qcompleter.html#highlighted">highlighted()</a> signal is connected to <tt>MainWindow</tt>'s <tt>highlight()</tt> slot.</p>
<pre> MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent), completer(0), lineEdit(0)
{
createMenu();
completer = new TreeModelCompleter(this);
completer->setModel(modelFromFile(":/resources/treemodel.txt"));
completer->setSeparator(QLatin1String("."));
QObject::connect(completer, SIGNAL(highlighted(QModelIndex)),
this, SLOT(highlight(QModelIndex)));
QWidget *centralWidget = new QWidget;
QLabel *modelLabel = new QLabel;
modelLabel->setText(tr("Tree Model<br>(Double click items to edit)"));
QLabel *modeLabel = new QLabel;
modeLabel->setText(tr("Completion Mode"));
modeCombo = new QComboBox;
modeCombo->addItem(tr("Inline"));
modeCombo->addItem(tr("Filtered Popup"));
modeCombo->addItem(tr("Unfiltered Popup"));
modeCombo->setCurrentIndex(1);
QLabel *caseLabel = new QLabel;
caseLabel->setText(tr("Case Sensitivity"));
caseCombo = new QComboBox;
caseCombo->addItem(tr("Case Insensitive"));
caseCombo->addItem(tr("Case Sensitive"));
caseCombo->setCurrentIndex(0);</pre>
<p>The <a href="qlabel.html">QLabel</a> objects <tt>modelLabel</tt>, <tt>modeLabel</tt> and <tt>caseLabel</tt> are instantiated. Also, the <a href="qcombobox.html">QComboBox</a> objects, <tt>modeCombo</tt> and <tt>caseCombo</tt>, are instantiated and populated. By default, the <tt>completer</tt>'s mode is "Filtered Popup" and the case is insensitive.</p>
<pre> QLabel *separatorLabel = new QLabel;
separatorLabel->setText(tr("Tree Separator"));
QLineEdit *separatorLineEdit = new QLineEdit;
separatorLineEdit->setText(completer->separator());
connect(separatorLineEdit, SIGNAL(textChanged(QString)),
completer, SLOT(setSeparator(QString)));
QCheckBox *wrapCheckBox = new QCheckBox;
wrapCheckBox->setText(tr("Wrap around completions"));
wrapCheckBox->setChecked(completer->wrapAround());
connect(wrapCheckBox, SIGNAL(clicked(bool)), completer, SLOT(setWrapAround(bool)));
contentsLabel = new QLabel;
contentsLabel->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
connect(separatorLineEdit, SIGNAL(textChanged(QString)),
this, SLOT(updateContentsLabel(QString)));
treeView = new QTreeView;
treeView->setModel(completer->model());
treeView->header()->hide();
treeView->expandAll();
connect(modeCombo, SIGNAL(activated(int)), this, SLOT(changeMode(int)));
connect(caseCombo, SIGNAL(activated(int)), this, SLOT(changeCase(int)));
lineEdit = new QLineEdit;
lineEdit->setCompleter(completer);</pre>
<p>We use a <a href="qgridlayout.html">QGridLayout</a> to place all the objects in the <tt>MainWindow</tt>.</p>
<pre> QGridLayout *layout = new QGridLayout;
layout->addWidget(modelLabel, 0, 0); layout->addWidget(treeView, 0, 1);
layout->addWidget(modeLabel, 1, 0); layout->addWidget(modeCombo, 1, 1);
layout->addWidget(caseLabel, 2, 0); layout->addWidget(caseCombo, 2, 1);
layout->addWidget(separatorLabel, 3, 0); layout->addWidget(separatorLineEdit, 3, 1);
layout->addWidget(wrapCheckBox, 4, 0);
layout->addWidget(contentsLabel, 5, 0, 1, 2);
layout->addWidget(lineEdit, 6, 0, 1, 2);
centralWidget->setLayout(layout);
setCentralWidget(centralWidget);
changeCase(caseCombo->currentIndex());
changeMode(modeCombo->currentIndex());
setWindowTitle(tr("Tree Model Completer"));
lineEdit->setFocus();
}</pre>
<p>The <tt>createMenu()</tt> function sets up the <a href="qaction.html">QAction</a> objects required and adds them to the "File" menu and "Help" menu. The <a href="qaction.html#triggered">triggered()</a> signals from these actions are connected to their respective slots.</p>
<pre> void MainWindow::createMenu()
{
QAction *exitAction = new QAction(tr("Exit"), this);
QAction *aboutAct = new QAction(tr("About"), this);
QAction *aboutQtAct = new QAction(tr("About Qt"), this);
connect(exitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
QMenu* fileMenu = menuBar()->addMenu(tr("File"));
fileMenu->addAction(exitAction);
QMenu* helpMenu = menuBar()->addMenu(tr("About"));
helpMenu->addAction(aboutAct);
helpMenu->addAction(aboutQtAct);
}</pre>
<p>The <tt>changeMode()</tt> function accepts an <i>index</i> corresponding to the user's choice of completion mode and changes the <tt>completer</tt>'s mode accordingly.</p>
<pre> void MainWindow::changeMode(int index)
{
QCompleter::CompletionMode mode;
if (index == 0)
mode = QCompleter::InlineCompletion;
else if (index == 1)
mode = QCompleter::PopupCompletion;
else
mode = QCompleter::UnfilteredPopupCompletion;
completer->setCompletionMode(mode);
}</pre>
<p>The <tt>about()</tt> function provides a brief description on the Tree Model Completer example.</p>
<pre> void MainWindow::about()
{
QMessageBox::about(this, tr("About"), tr("This example demonstrates how "
"to use a QCompleter with a custom tree model."));
}</pre>
<p>The <tt>changeCase()</tt> function alternates between <a href="qt.html#CaseSensitivity-enum">Case Sensitive</a> and <a href="qt.html#CaseSensitivity-enum">Case Insensitive</a> modes, depending on the value of <i>cs</i>.</p>
<pre> void MainWindow::changeCase(int cs)
{
completer->setCaseSensitivity(cs ? Qt::CaseSensitive : Qt::CaseInsensitive);
}</pre>
<a name="function"></a>
<h2><tt>main()</tt> Function</h2>
<p>The <tt>main()</tt> function instantiates <tt>MainWindow</tt> and invokes the <a href="qwidget.html#show">show()</a> function to display it.</p>
<pre> int main(int argc, char *argv[])
{
Q_INIT_RESOURCE(treemodelcompleter);
QApplication app(argc, argv);
MainWindow window;
window.show();
return app.exec();
}</pre>
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<td width="40%" align="left">Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies)</td>
<td width="20%" align="center"><a href="trademarks.html">Trademarks</a></td>
<td width="40%" align="right"><div align="right">Qt 4.6.3</div></td>
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