How disable copy and paste on QLineEdit

tmtt66

How disable copy and paste on QLineEdit?

jazzycamel

Generally speaking I would discourage this kind of thing as it can be incredibly annoying for the user. Saying that, I have been in a situation where I had no choice so developed the following simple class:

#include <QtGui/QLineEdit>
#include <QtGui/QKeyEvent>
class LineEdit : public QLineEdit
{
    Q_OBJECT
public:
    LineEdit(QWidget *parent=0) : QLineEdit(parent){ init(); }
    LineEdit(const QString &contents, QWidget *parent=0) : QLineEdit(contents,parent){ init(); }

private:
    void init(){
        setAcceptDrops(false);
        setContextMenuPolicy(Qt::CustomContextMenu);
        connect(this, SIGNAL(customContextMenuRequested(QPoint)), SLOT(showMenu(QPoint)));
    }

protected:
    void keyPressEvent(QKeyEvent *event){
        if(event->matches(QKeySequence::Copy) || event->matches(QKeySequence::Cut) || event->matches(QKeySequence::Paste))
            event->ignore();
        else return QLineEdit::keyPressEvent(event);
    }

private slots:
    void showMenu(QPoint position){}
};

It basically works by:

Catching the "QKeyEvent":http://qt-project.org/doc/qt-4.8/qkeyevent.html for the copy, cut and paste "QKeySequences":http://qt-project.org/doc/qt-4.8/qkeysequence.html and preventing there propagation,
Preventing the user from dragging and dropping data ("setAcceptDrops":http://qt-project.org/doc/qt-4.8/qwidget.html#acceptDrops-prop), and
Redirecting a request for a context menu to a custom slot to prevent the system menu being shown with the cut, copy and paste actions and allowing for the implementation of a custom menu.

Hope this helps ;o)