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diff --git a/doc/src/examples/customcompleter.qdoc b/doc/src/examples/customcompleter.qdoc new file mode 100644 index 0000000000..8d0404a281 --- /dev/null +++ b/doc/src/examples/customcompleter.qdoc @@ -0,0 +1,201 @@ +/**************************************************************************** +** +** 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. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \example tools/customcompleter + \title Custom Completer Example + + The Custom Completer example shows how to provide string-completion + facilities for an input widget based on data provided by a model. The + completer pops up suggestions for possible words based on the first three + characters input by the user and the user's choice of word is inserted + into the \c TextEdit using QTextCursor. + + \image customcompleter-example.png + + \section1 Setting Up The Resource File + + The Custom Completer example requires a resource file, \e wordlist.txt, + that has a list of words to help QCompleter complete words. This file + contains the following: + + \quotefile examples/tools/customcompleter/customcompleter.qrc + + \section1 TextEdit Class Definition + + The \c TextEdit class is a subclass of QTextEdit with a custom + \c insertCompletion() slot and it reimplements the + \l{QAbstractScrollArea::keyPressEvent()}{keyPressEvent()} and the + \l{QWidget::focusInEvent()}{focusInEvent()} functions. \c TextEdit also + contains a private function \c textUnderCursor() and a private instance + of QCompleter, \c c. + + \snippet examples/tools/customcompleter/textedit.h 0 + + \section1 TextEdit Class Implementation + + The constructor for \c TextEdit constructs a \c TextEdit with a parent and + initializes \c c. The instructions to use the completer is displayed on + the \c TextEdit object, using the + \l{QTextEdit::setPlainText()}{setPlainText()} function. + + \snippet examples/tools/customcompleter/textedit.cpp 0 + + In addition, \c TextEdit also includes a default destructor: + + \snippet examples/tools/customcompleter/textedit.cpp 1 + + The \c setCompleter() function accepts a \a completer and sets it up. + We use \c{if (c)} to check if \c c has been initialized. If it has been + initialized, the QObject::disconnect() function is invoked to disconnect + the signal from the slot. This is to ensure that no previous completer + object is still connected to the slot. + + \snippet examples/tools/customcompleter/textedit.cpp 2 + + We then instantiate \c c with \a completer and set it as \c{TextEdit}'s + widget. The completion mode and case sensitivity are also set and then + we connect the \l{QCompleter::activated()}{activated()} signal to the + \c insertCompletion() slot. + + The \c completer() function is a getter function that returns \c c. + + \snippet examples/tools/customcompleter/textedit.cpp 3 + + The completer pops up the options available, based on the contents of + \e wordlist.txt, but the text cursor is responsible for filling in the + missing characters, according to the user's choice of word. + + Suppose the user inputs "ACT" and accepts the completer's suggestion of + "ACTUAL". The \c completion string is then sent to \c insertCompletion() + by the completer's \l{QCompleter::activated()}{activated()} signal. + + The \c insertCompletion() function is responsible for completing the word + using a QTextCursor object, \c tc. It validates to ensure that the + completer's widget is \c TextEdit before using \c tc to insert the extra + characters to complete the word. + + \snippet examples/tools/customcompleter/textedit.cpp 4 + + The figure below illustrates this process: + + \image customcompleter-insertcompletion.png + + \c{completion.length()} = 6 + + \c{c->completionPrefix().length()}=3 + + The difference between these two values is \c extra, which is 3. This + means that the last three characters from the right, "U", "A", and "L", + will be inserted by \c tc. + + The \c textUnderCursor() function uses a QTextCursor, \c tc, to select a + word under the cursor and return it. + + \snippet examples/tools/customcompleter/textedit.cpp 5 + + The \c TextEdit class reimplements \l{QWidget::focusInEvent()} + {focusInEvent()} function, which is an event handler used to receive + keyboard focus events for the widget. + + \snippet examples/tools/customcompleter/textedit.cpp 6 + + The \l{QAbstractScrollArea::keyPressEvent()}{keyPressEvent()} is + reimplemented to ignore key events like Qt::Key_Enter, Qt::Key_Return, + Qt::Key_Escape, Qt::Key_Tab, and Qt::Key_Backtab so the completer can + handle them. + + If there is an active completer, we cannot process the shortcut, Ctrl+E. + + \snippet examples/tools/customcompleter/textedit.cpp 7 + + We also handle other modifiers and shortcuts for which we do not want the + completer to respond to. + + \snippet examples/tools/customcompleter/textedit.cpp 8 + + Finally, we pop up the completer. + + \section1 MainWindow Class Definition + + The \c MainWindow class is a subclass of QMainWindow and implements a + private slot, \c about(). This class also has two private functions, + \c createMenu() and \c modelFromFile() as well as private instances of + QCompleter and \c TextEdit. + + \snippet examples/tools/customcompleter/mainwindow.h 0 + + \section1 MainWindow Class Implementation + + The constructor constructs a \c MainWindow with a parent and initializes + the \c completer. It also instantiates a \c TextEdit and sets its + completer. A QStringListModel, obtained from \c modelFromFile(), is used + to populate the \c completer. The \c{MainWindow}'s central widget is set + to \c TextEdit and its size is set to 500 x 300. + + \snippet examples/tools/customcompleter/mainwindow.cpp 0 + + The \c createMenu() function creates the necessary QAction objects needed + for the "File" and "Help" menu and their \l{QAction::triggered()} + {triggered()} signals are connected to the \c quit(), \c about(), and + \c aboutQt() slots respectively. + + \snippet examples/tools/customcompleter/mainwindow.cpp 1 + + The \c modelFromFile() function accepts a \a fileName and attempts to + extract the contents of this file into a QStringListModel. We display the + Qt::WaitCursor when we are populating the QStringList, \c words, and + restore the mouse cursor when we are done. + + \snippet examples/tools/customcompleter/mainwindow.cpp 2 + + The \c about() function provides a brief description about the Custom + Completer example. + + \snippet examples/tools/customcompleter/mainwindow.cpp 3 + + \section1 \c main() Function + + The \c main() function instantiates \c MainWindow and invokes the + \l{QWidget::show()}{show()} function. + + \snippet examples/tools/customcompleter/main.cpp 0 +*/ |