사용자 정의 자동 완성 예제

<!DOCTYPE RCC><RCC version="1.0">
<qresource prefix="/">
   <file>resources/wordlist.txt</file>
</qresource>
</RCC>

class TextEdit : public QTextEdit
{
    Q_OBJECT

public:
    TextEdit(QWidget *parent = nullptr);
    ~TextEdit();

    void setCompleter(QCompleter *c);
    QCompleter *completer() const;

protected:
    void keyPressEvent(QKeyEvent *e) override;
    void focusInEvent(QFocusEvent *e) override;

private slots:
    void insertCompletion(const QString &completion);

private:
    QString textUnderCursor() const;

private:
    QCompleter *c = nullptr;
};

TextEdit::TextEdit(QWidget *parent)
    : QTextEdit(parent)
{
    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)
        c->disconnect(this);

    c = completer;

    if (!c)
        return;

    c->setWidget(this);
    c->setCompletionMode(QCompleter::PopupCompletion);
    c->setCaseSensitivity(Qt::CaseInsensitive);
    QObject::connect(c, QOverload<const QString &>::of(&QCompleter::activated),
                     this, &TextEdit::insertCompletion);
}

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;
       }
    }

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

    static QString eow("~!@#$%^&*()_+{}|:\"<>?,./;'[]\\-="); // end of word
    const 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!
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);

private slots:
    void about();

private:
    void createMenu();
    QAbstractItemModel *modelFromFile(const QString& fileName);

    QCompleter *completer = nullptr;
    TextEdit *completingTextEdit;
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    createMenu();

    completingTextEdit = new TextEdit;
    completer = new QCompleter(this);
    completer->setModel(modelFromFile(":/resources/wordlist.txt"));
    completer->setModelSorting(QCompleter::CaseInsensitivelySortedModel);
    completer->setCaseSensitivity(Qt::CaseInsensitive);
    completer->setWrapAround(false);
    completingTextEdit->setCompleter(completer);

    setCentralWidget(completingTextEdit);
    resize(500, 300);
    setWindowTitle(tr("Completer"));
}

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, &QAction::triggered, qApp, &QApplication::quit);
    connect(aboutAct, &QAction::triggered, this, &MainWindow::about);
    connect(aboutQtAct, &QAction::triggered, qApp, &QApplication::aboutQt);

    QMenu *fileMenu = menuBar()->addMenu(tr("File"));
    fileMenu->addAction(exitAction);

    QMenu *helpMenu = menuBar()->addMenu(tr("About"));
    helpMenu->addAction(aboutAct);
    helpMenu->addAction(aboutQtAct);
}

QAbstractItemModel *MainWindow::modelFromFile(const QString& fileName)
{
    QFile file(fileName);
    if (!file.open(QFile::ReadOnly))
        return new QStringListModel(completer);

#ifndef QT_NO_CURSOR
    QGuiApplication::setOverrideCursor(QCursor(Qt::WaitCursor));
#endif
    QStringList words;

    while (!file.atEnd()) {
        QByteArray line = file.readLine();
        if (!line.isEmpty())
            words << QString::fromUtf8(line.trimmed());
    }

#ifndef QT_NO_CURSOR
    QGuiApplication::restoreOverrideCursor();
#endif
    return new QStringListModel(words, completer);
}

void MainWindow::about()
{
    QMessageBox::about(this, tr("About"), tr("This example demonstrates the "
        "different features of the QCompleter class."));
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MainWindow window;
    window.show();
    return app.exec();
}