- Qt 5.5
- Qt Widgets
- Custom Completer Example
- textedit.cpp Example File
- Qt 5.5.1 Reference Documentation

# textedit.cpp Example File

tools/customcompleter/textedit.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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    ****************************************************************************/

    #include "textedit.h"
    #include <QCompleter>
    #include <QKeyEvent>
    #include <QAbstractItemView>
    #include <QtDebug>
    #include <QApplication>
    #include <QModelIndex>
    #include <QAbstractItemModel>
    #include <QScrollBar>

    TextEdit::TextEdit(QWidget *parent)
    : QTextEdit(parent), c(0)
    {
        setPlainText(tr("This TextEdit provides autocompletions for words that have more than"
                        " 3 characters. You can trigger autocompletion using ") +
                        QKeySequence("Ctrl+E").toString(QKeySequence::NativeText));
    }

    TextEdit::~TextEdit()
    {
    }

    void TextEdit::setCompleter(QCompleter *completer)
    {
        if (c)
            QObject::disconnect(c, 0, this, 0);

        c = completer;

        if (!c)
            return;

        c->setWidget(this);
        c->setCompletionMode(QCompleter::PopupCompletion);
        c->setCaseSensitivity(Qt::CaseInsensitive);
        QObject::connect(c, SIGNAL(activated(QString)),
                         this, SLOT(insertCompletion(QString)));
    }

    QCompleter *TextEdit::completer() const
    {
        return c;
    }

    void TextEdit::insertCompletion(const QString& completion)
    {
        if (c->widget() != this)
            return;
        QTextCursor tc = textCursor();
        int extra = completion.length() - c->completionPrefix().length();
        tc.movePosition(QTextCursor::Left);
        tc.movePosition(QTextCursor::EndOfWord);
        tc.insertText(completion.right(extra));
        setTextCursor(tc);
    }

    QString TextEdit::textUnderCursor() const
    {
        QTextCursor tc = textCursor();
        tc.select(QTextCursor::WordUnderCursor);
        return tc.selectedText();
    }

    void TextEdit::focusInEvent(QFocusEvent *e)
    {
        if (c)
            c->setWidget(this);
        QTextEdit::focusInEvent(e);
    }

    void TextEdit::keyPressEvent(QKeyEvent *e)
    {
        if (c && c->popup()->isVisible()) {
            // The following keys are forwarded by the completer to the widget
           switch (e->key()) {
           case Qt::Key_Enter:
           case Qt::Key_Return:
           case Qt::Key_Escape:
           case Qt::Key_Tab:
           case Qt::Key_Backtab:
                e->ignore();
                return; // let the completer do default behavior
           default:
               break;
           }
        }

        bool isShortcut = ((e->modifiers() & Qt::ControlModifier) && e->key() == Qt::Key_E); // CTRL+E
        if (!c || !isShortcut) // do not process the shortcut when we have a completer
            QTextEdit::keyPressEvent(e);

        const bool ctrlOrShift = e->modifiers() & (Qt::ControlModifier | Qt::ShiftModifier);
        if (!c || (ctrlOrShift && e->text().isEmpty()))
            return;

        static QString eow("~!@#$%^&*()_+{}|:\"<>?,./;'[]\\-="); // end of word
        bool hasModifier = (e->modifiers() != Qt::NoModifier) && !ctrlOrShift;
        QString completionPrefix = textUnderCursor();

        if (!isShortcut && (hasModifier || e->text().isEmpty()|| completionPrefix.length() < 3
                          || eow.contains(e->text().right(1)))) {
            c->popup()->hide();
            return;
        }

        if (completionPrefix != c->completionPrefix()) {
            c->setCompletionPrefix(completionPrefix);
            c->popup()->setCurrentIndex(c->completionModel()->index(0, 0));
        }
        QRect cr = cursorRect();
        cr.setWidth(c->popup()->sizeHintForColumn(0)
                    + c->popup()->verticalScrollBar()->sizeHint().width());
        c->complete(cr); // popup it up!
    }