[Qt-interest] QLineEdit - disable undo/redo Accelerators and pass to containing widget ?

[Colin S. Miller]

Hi,

I'm trying to prevent a class (here EnhancedLineEdit) which is derived from QLineEdit
from handling the CTRL-Z and CTRL-Y keys, and instead allow the containing class
(here MainWindow) to handle it.

It is my understanding if a class's event() function returns FALSE, then the event
is passed to the containing widget.

However, the CTRL-Z isn't passed on to MainWindow::event() in my code.



TIA,
Colin S. Miller

/* build with
  * moc -f foo.cpp -o moc_foo.cpp && \
  * LANG=C gcc -o foo moc_foo.cpp -I/usr/include/qt3/ -lqt-mt -g -Wall -Wno-switch
  */
#include <iostream>
#include <qapplication.h>
#include <qlayout.h>
#include <qlineedit.h>
#include <qmenubar.h>
#include <qpopupmenu.h>
#include <qevent.h>

#define BLOCK_UNDO_IN_RAW_EVENT

class EnhancedLineEdit : public QLineEdit
{
     Q_OBJECT

public:
     EnhancedLineEdit(QWidget *parent);

protected:
     virtual bool event   (QEvent * e);       /* overrides parent */
     virtual QPopupMenu * createPopupMenu();  /* overrides parent */

     virtual void keyPressEvent(QKeyEvent *e);
};

class MainWindow : public QWidget
{
   Q_OBJECT

public:
   MainWindow(void);

private slots:
    void undo(void);
    void redo(void);

protected:
     virtual void keyPressEvent(QKeyEvent *e);
};


EnhancedLineEdit::EnhancedLineEdit(QWidget*parent) : QLineEdit(parent)
{
};

bool EnhancedLineEdit::event(QEvent *evt)
{
#ifdef BLOCK_UNDO_IN_RAW_EVENT
     switch (evt->type())
     {
         case QEvent::KeyPress:
         {
             QKeyEvent *keyEvt = dynamic_cast<QKeyEvent*>(evt);
             if ( keyEvt->state() & ControlButton )
             {
                 switch (keyEvt->key())
                 {
                     case Key_Z:
                     case Key_Y:
                         return FALSE;
                     break;
                 }
             }
         }
         break;
     }
#endif

     return  QLineEdit::event(evt);
}

QPopupMenu *EnhancedLineEdit::createPopupMenu()
{
     /* no context menu, also disables its short cuts */
     return NULL;
}



void EnhancedLineEdit::keyPressEvent(QKeyEvent* e)
{
     std::cout << "In EnhancedLineEdit::keyPressEvent" << std::endl;

#ifndef BLOCK_UNDO_IN_RAW_EVENT
     if ( e->state() & ControlButton )
     {
         switch (e->key())
         {
             case Key_Z:
             case Key_Y:
                 return;
             break;
         }
     }
#endif

     QLineEdit::keyPressEvent(e);
}




MainWindow::MainWindow() : QWidget()
{
     QGridLayout  *layout;
     QMenuBar *menuBar = new QMenuBar(this);
     QPopupMenu *edit = new QPopupMenu( this );
     EnhancedLineEdit *line;

     edit->insertItem( "&Undo",  this, SLOT(undo()), CTRL+Key_Z );
     edit->insertItem( "&Redo", this, SLOT(redo()), CTRL+Key_Y );
     menuBar->insertItem( "&Edit", edit );

     layout = new QGridLayout(this, 2, 1);
     layout->addWidget(menuBar, 0, 0);

     line = new EnhancedLineEdit(this);
     layout->addWidget(line, 1, 0);
}

void MainWindow::undo(void)
{
     std::cout << "MainWindow::undo" << std::endl;
}


void MainWindow::redo(void)
{
     std::cout << "MainWindow::redo" << std::endl;
}


void MainWindow::keyPressEvent(QKeyEvent* e)
{
     std::cout << "In MainWindow::keyPressEvent" << std::endl;
     QWidget::keyPressEvent(e);
}



int main(int argc, char** argv)
{
   QApplication qapp(argc, argv);
   MainWindow mainWindow;
   mainWindow.show();

   qapp.setMainWidget(&mainWindow);
   qapp.exec();
}