How to change completion rule of QCompleter

[numbat]

Using this QCompleter example and this custom QCompleter example, I implemented what you want.

Header:

#ifndef LINEEDIT_H
#define LINEEDIT_H
 
#include <QLineEdit>
#include <QStringList>
#include <QStringListModel>
#include <QString>
#include <QCompleter>
 
class MyCompleter : public QCompleter
{
    Q_OBJECT
 
public:
    inline MyCompleter(const QStringList& words, QObject * parent) :
            QCompleter(parent), m_list(words), m_model()
    {
        setModel(&m_model);
    }
 
    inline void update(QString word)
    {
        // Do any filtering you like.
        // Here we just include all items that contain word.
        QStringList filtered = m_list.filter(word, caseSensitivity());
        m_model.setStringList(filtered);
        m_word = word;
        complete();
    }
 
    inline QString word()
    {
        return m_word;
    }
 
private:
    QStringList m_list;
    QStringListModel m_model;
    QString m_word;
};
 
class MyLineEdit : public QLineEdit
{
    Q_OBJECT
 
public:
    MyLineEdit(QWidget *parent = 0);
    ~MyLineEdit();
 
    void setCompleter(MyCompleter *c);
    MyCompleter *completer() const;
 
protected:
    void keyPressEvent(QKeyEvent *e);
 
private slots:
    void insertCompletion(const QString &completion);
 
private:
    MyCompleter *c;
};
 
#endif // LINEEDIT_H

#ifndef LINEEDIT_H
#define LINEEDIT_H

#include <QLineEdit>
#include <QStringList>
#include <QStringListModel>
#include <QString>
#include <QCompleter>

class MyCompleter : public QCompleter
{
    Q_OBJECT

public:
    inline MyCompleter(const QStringList& words, QObject * parent) :
            QCompleter(parent), m_list(words), m_model()
    {
        setModel(&m_model);
    }

    inline void update(QString word)
    {
        // Do any filtering you like.
        // Here we just include all items that contain word.
        QStringList filtered = m_list.filter(word, caseSensitivity());
        m_model.setStringList(filtered);
        m_word = word;
        complete();
    }

    inline QString word()
    {
        return m_word;
    }

private:
    QStringList m_list;
    QStringListModel m_model;
    QString m_word;
};

class MyLineEdit : public QLineEdit
{
    Q_OBJECT

public:
    MyLineEdit(QWidget *parent = 0);
    ~MyLineEdit();

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

protected:
    void keyPressEvent(QKeyEvent *e);

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

private:
    MyCompleter *c;
};

#endif // LINEEDIT_H

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CPP:

MyLineEdit::MyLineEdit(QWidget *parent)
    : QLineEdit(parent), c(0)
{
}
 
MyLineEdit::~MyLineEdit()
{
}
 
void MyLineEdit::setCompleter(MyCompleter *completer)
{
    if (c)
        QObject::disconnect(c, 0, this, 0);
 
    c = completer;
 
    if (!c)
        return;
 
    c->setWidget(this);
    connect(completer, SIGNAL(activated(const QString&)), this, SLOT(insertCompletion(const QString&)));
}
 
MyCompleter *MyLineEdit::completer() const
{
    return c;
}
 
void MyLineEdit::insertCompletion(const QString& completion)
{
    setText(completion);
    selectAll();
}
 
 
void MyLineEdit::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
        }
    }
 
    bool isShortcut = (e->modifiers() & Qt::ControlModifier) && e->key() == Qt::Key_E;
    if (!isShortcut)
        QLineEdit::keyPressEvent(e); // Don't send the shortcut (CTRL-E) to the text edit.
 
    if (!c)
        return;
 
    bool ctrlOrShift = e->modifiers() & (Qt::ControlModifier | Qt::ShiftModifier);
    if (!isShortcut && !ctrlOrShift && e->modifiers() != Qt::NoModifier)
    {
        c->popup()->hide();
        return;
    }
 
    c->update(text());
    c->popup()->setCurrentIndex(c->completionModel()->index(0, 0));
}

MyLineEdit::MyLineEdit(QWidget *parent)
    : QLineEdit(parent), c(0)
{
}

MyLineEdit::~MyLineEdit()
{
}

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

    c = completer;

    if (!c)
        return;

    c->setWidget(this);
    connect(completer, SIGNAL(activated(const QString&)), this, SLOT(insertCompletion(const QString&)));
}

MyCompleter *MyLineEdit::completer() const
{
    return c;
}

void MyLineEdit::insertCompletion(const QString& completion)
{
    setText(completion);
    selectAll();
}


void MyLineEdit::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
        }
    }

    bool isShortcut = (e->modifiers() & Qt::ControlModifier) && e->key() == Qt::Key_E;
    if (!isShortcut)
        QLineEdit::keyPressEvent(e); // Don't send the shortcut (CTRL-E) to the text edit.

    if (!c)
        return;

    bool ctrlOrShift = e->modifiers() & (Qt::ControlModifier | Qt::ShiftModifier);
    if (!isShortcut && !ctrlOrShift && e->modifiers() != Qt::NoModifier)
    {
        c->popup()->hide();
        return;
    }

    c->update(text());
    c->popup()->setCurrentIndex(c->completionModel()->index(0, 0));
}

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Usage:

MyLineEdit * te = new MyLineEdit;
     MyCompleter * completer = new MyCompleter(QStringList() << "oneone" << "Twotwo", this);
     completer->setCaseSensitivity(Qt::CaseInsensitive);
     te->setCompleter(completer);

MyLineEdit * te = new MyLineEdit;
     MyCompleter * completer = new MyCompleter(QStringList() << "oneone" << "Twotwo", this);
     completer->setCaseSensitivity(Qt::CaseInsensitive);
     te->setCompleter(completer);

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