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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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****************************************************************************/
/*!
\example tools/completer
\title Completer Example
The Completer example shows how to provide string-completion facilities
for an input widget based on data provided by a model.
\image completer-example.png
This example uses a custom item model, \c DirModel, and a QCompleter object.
QCompleter is a class that provides completions based on an item model. The
type of model, the completion mode, and the case sensitivity can be
selected using combo boxes.
\section1 The Resource File
The Completer example requires a resource file in order to store the
\e{countries.txt} and \e{words.txt}. The resource file contains the
following code:
\quotefile examples/tools/completer/completer.qrc
\section1 DirModel Class Definition
The \c DirModel class is a subclass of QDirModel, which provides a data
model for the local filesystem.
\snippet examples/tools/completer/dirmodel.h 0
This class only has a constructor and a \c data() function as it is only
created to enable \c data() to return the entire file path for the
display role, unlike \l{QDirModel}'s \c data() function that only returns
the folder and not the drive label. This is further explained in
\c DirModel's implementation.
\section1 DirModel Class Implementation
The constructor for the \c DirModel class is used to pass \a parent to
QDirModel.
\snippet examples/tools/completer/dirmodel.cpp 0
As mentioned earlier, the \c data() function is reimplemented in order to
get it to return the entire file parth for the display role. For example,
with a QDirModel, you will see "Program Files" in the view. However, with
\c DirModel, you will see "C:\\Program Files".
\snippet examples/tools/completer/dirmodel.cpp 1
The screenshots below illustrate this difference:
\table
\row \o \inlineimage completer-example-qdirmodel.png
\o \inlineimage completer-example-dirmodel.png
\endtable
The Qt::EditRole, which QCompleter uses to look for matches, is left
unchanged.
\section1 MainWindow Class Definition
The \c MainWindow class is a subclass of QMainWindow and implements four
private slots - \c about(), \c changeCase(), \c changeMode(), and
\c changeModel().
\snippet examples/tools/completer/mainwindow.h 0
Within the \c MainWindow class, we have two private functions:
\c createMenu() and \c modelFromFile(). We also declare the private widgets
needed - three QComboBox objects, a QCheckBox, a QCompleter, a QLabel, and
a QLineEdit.
\snippet examples/tools/completer/mainwindow.h 1
\section1 MainWindow Class Implementation
The constructor of \c MainWindow constructs a \c MainWindow with a parent
widget and initializes the private members. The \c createMenu() function
is then invoked.
We set up three QComboBox objects, \c modelComb, \c modeCombo and
\c caseCombo. By default, the \c modelCombo is set to QDirModel,
the \c modeCombo is set to "Filtered Popup" and the \c caseCombo is set
to "Case Insensitive".
\snippet examples/tools/completer/mainwindow.cpp 0
The \c wrapCheckBox is then set up. This \c checkBox determines if the
\c{completer}'s \l{QCompleter::setWrapAround()}{setWrapAround()} property
is enabled or disabled.
\snippet examples/tools/completer/mainwindow.cpp 1
We instantiate \c contentsLabel and set its size policy to
\l{QSizePolicy::Fixed}{fixed}. The combo boxes' \l{QComboBox::activated()}
{activated()} signals are then connected to their respective slots.
\snippet examples/tools/completer/mainwindow.cpp 2
The \c lineEdit is set up and then we arrange all the widgets using a
QGridLayout. The \c changeModel() function is called, to initialize the
\c completer.
\snippet examples/tools/completer/mainwindow.cpp 3
The \c createMenu() function is used to instantiate the QAction objects
needed to fill the \c fileMenu and \c helpMenu. The actions'
\l{QAction::triggered()}{triggered()} signals are connected to their
respective slots.
\snippet examples/tools/completer/mainwindow.cpp 4
The \c modelFromFile() function accepts the \a fileName of a file and
processes it depending on its contents.
We first validate the \c file to ensure that it can be opened in
QFile::ReadOnly mode. If this is unsuccessful, the function returns an
empty QStringListModel.
\snippet examples/tools/completer/mainwindow.cpp 5
The mouse cursor is then overriden with Qt::WaitCursor before we fill
a QStringList object, \c words, with the contents of \c file. Once this
is done, we restore the mouse cursor.
\snippet examples/tools/completer/mainwindow.cpp 6
As mentioned earlier, the resources file contains two files -
\e{countries.txt} and \e{words.txt}. If the \c file read is \e{words.txt},
we return a QStringListModel with \c words as its QStringList and
\c completer as its parent.
\snippet examples/tools/completer/mainwindow.cpp 7
If the \c file read is \e{countries.txt}, then we require a
QStandardItemModel with \c words.count() rows, 2 columns, and \c completer
as its parent.
\snippet examples/tools/completer/mainwindow.cpp 8
A standard line in \e{countries.txt} is:
\quotation
Norway NO
\endquotation
Hence, to populate the QStandardItemModel object, \c m, we have to
split the country name and its symbol. Once this is done, we return
\c m.
\snippet examples/tools/completer/mainwindow.cpp 9
The \c changeMode() function sets the \c{completer}'s mode, depending on
the value of \c index.
\snippet examples/tools/completer/mainwindow.cpp 10
The \c changeModel() function changes the item model used based on the
model selected by the user.
A \c switch statement is used to change the item model based on the index
of \c modelCombo. If \c case is 0, we use an unsorted QDirModel, providing
us with a file path excluding the drive label.
\snippet examples/tools/completer/mainwindow.cpp 11
Note that we create the model with \c completer as the parent as this
allows us to replace the model with a new model. The \c completer will
ensure that the old one is deleted the moment a new model is assigned
to it.
If \c case is 1, we use the \c DirModel we defined earlier, resulting in
full paths for the files.
\snippet examples/tools/completer/mainwindow.cpp 12
When \c case is 2, we attempt to complete names of countries. This requires
a QTreeView object, \c treeView. The country names are extracted from
\e{countries.txt} and set the popup used to display completions to
\c treeView.
\snippet examples/tools/completer/mainwindow.cpp 13
The screenshot below shows the Completer with the country list model.
\image completer-example-country.png
If \c case is 3, we attempt to complete words. This is done using a
QStringListModel that contains data extracted from \e{words.txt}. The
model is sorted \l{QCompleter::CaseInsensitivelySortedModel}
{case insensitively}.
The screenshot below shows the Completer with the word list model.
\image completer-example-word.png
Once the model type is selected, we call the \c changeMode() function and
the \c changeCase() function and set the wrap option accordingly. The
\c{wrapCheckBox}'s \l{QCheckBox::clicked()}{clicked()} signal is connected
to the \c{completer}'s \l{QCompleter::setWrapAround()}{setWrapAround()}
slot.
\snippet examples/tools/completer/mainwindow.cpp 14
The \c about() function provides a brief description about the example.
\snippet examples/tools/completer/mainwindow.cpp 15
\section1 \c main() Function
The \c main() function instantiates QApplication and \c MainWindow and
invokes the \l{QWidget::show()}{show()} function.
\snippet examples/tools/completer/main.cpp 0
*/
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