Which event when raising a window

[Caius Aérobus]

Hello,
I have 2 main windows and I would like that each time one of them is raised by the user - by clicking on it - the other one be raised so as to always have all windows either visible or not, ie not hidden by another application (otherwise I have to raise each window individually).
I was about to solve it by overloading the changeEvent() method but this method is not called when a window is raised by clicking on it. Any idea?

void
myClass::changeEvent(QEvent *event)
{
  if (event->type() == QEvent::WindowStateChange) {
    if (this->windowState() & Qt::WindowActive) {
      printf("raised\n");
    }
    QWidget::changeEvent(event);
  }
}

void
myClass::changeEvent(QEvent *event)
{
  if (event->type() == QEvent::WindowStateChange) {
    if (this->windowState() & Qt::WindowActive) {
      printf("raised\n");
    }
    QWidget::changeEvent(event);
  }
}

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[wysota]

Are you aware that clicking on a window doesn't have to bring it to front? This depends on the settings of the window manager. I don't think there is an event that handles what you want. You might try your luck with monitoring QApplication::focusChanged() signal however it is related to keyboard focus and not window visibility. You can also try with your current approach but so far you have been looking for a wrong event -- try checking for QEvent::ActivationChange instead.

[Caius Aérobus]

Tried it but did not change anything, ie slot is not called.

[wysota]

What slot do you mean?

[Caius Aérobus]

According to your suggestion, I tried this:

void
myClass::changeEvent(QEvent *event)
{
    if (event->type() == QEvent::ActivationChange) {
        if (this->windowState() & Qt::WindowActive) {
            printf("raised\n");
        }
        QWidget::changeEvent(event);
    }
}

void
myClass::changeEvent(QEvent *event)
{
    if (event->type() == QEvent::ActivationChange) {
        if (this->windowState() & Qt::WindowActive) {
            printf("raised\n");
        }
        QWidget::changeEvent(event);
    }
}

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and I expected that clicking on the upper band of the window, making it the active window, would have made this slot executed.

[wysota]

It's not a slot.

And the docs say:

QEvent::ActivationChange 99 A widget's top-level window activation state has changed.

Again, it has nothing to do with the window being raised or not. Activation is related to the keyboard focus.

[Caius Aérobus]

You wrote:

try checking for QEvent::ActivationChange instead

so that is the reason I tried it!

[wysota]

I have also written other things. Have you checked them?

[Caius Aérobus]

Yes I understood that it is not possible to have all windows of an application raised together when one of them has been raised.
I just investigated this route since you mentionned it.

[wysota]

I meant the focusChanged() signal.

[Spitfire]

I don't know about chaning focus wysota mentioned, but changeEvent works perfectly fine on w7 an ubuntu for me:

// main
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
 
    MainWindow w2;
    w2.show();
 
    QObject::connect( &w, SIGNAL( activated( QWidget* ) ), &w2, SLOT( activate( QWidget* ) ) );
    QObject::connect( &w2, SIGNAL( activated( QWidget* ) ), &w, SLOT( activate( QWidget* ) ) );
 
    return a.exec();
}

// main
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    MainWindow w2;
    w2.show();

    QObject::connect( &w, SIGNAL( activated( QWidget* ) ), &w2, SLOT( activate( QWidget* ) ) );
    QObject::connect( &w2, SIGNAL( activated( QWidget* ) ), &w, SLOT( activate( QWidget* ) ) );

    return a.exec();
}

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// mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui/QMainWindow>
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow( QWidget* parent = 0 );
 
protected:
    void    changeEvent( QEvent* e );
 
public slots:
    void    activate( QWidget* w );
 
signals:
    void    activated( QWidget* w );
};
 
#endif // MAINWINDOW_H

// mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui/QMainWindow>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow( QWidget* parent = 0 );

protected:
    void    changeEvent( QEvent* e );

public slots:
    void    activate( QWidget* w );

signals:
    void    activated( QWidget* w );
};

#endif // MAINWINDOW_H

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// mainwindow.cpp
#include "mainwindow.h"
 
#include <QEvent>
 
MainWindow::MainWindow( QWidget* p )
    :
    QMainWindow( p )
{
}
 
void    MainWindow::changeEvent( QEvent* e )
{
    if( e->type() == QEvent::ActivationChange
        && this->isActiveWindow() )
    {
        emit this->activated( this );
    }
    QMainWindow::changeEvent( e );
}
 
void MainWindow::activate( QWidget* w )
{
    this->raise();
    this->stackUnder( w );
}

// mainwindow.cpp
#include "mainwindow.h"

#include <QEvent>

MainWindow::MainWindow( QWidget* p )
    :
    QMainWindow( p )
{
}

void    MainWindow::changeEvent( QEvent* e )
{
    if( e->type() == QEvent::ActivationChange
        && this->isActiveWindow() )
    {
        emit this->activated( this );
    }
    QMainWindow::changeEvent( e );
}

void MainWindow::activate( QWidget* w )
{
    this->raise();
    this->stackUnder( w );
}

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[JFPERREARD]

Very good, thank you for this help,
Ok with QT5 on Windows 8