Display a QWidget using multi-screen

[tarod]

Hello,

I've got two monitors in Linux configured as multi-screen, so I've two monitors connected to one graphic card. I'm trying to display a QWidget on upper or lower monitor using QDesktopWidget, but I'm doing something wrong because I can't do it.

I leave some code below to understand better my issue:

The class inherits QWidget:

IFHMIQtGui(QWidget* parent, GUIDevice device)

IFHMIQtGui(QWidget* parent, GUIDevice device)

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The constructor:

IFHMIQtGui::IFHMIQtGui(QWidget* parent, GUIDevice device)
{
   QDesktopWidget pDesktop;
   QWidget *qscreen;
 
   if (device == DEVICE_UPPER)
   {
       qscreen = pDesktop.screen(1);
   }
   else if (device == DEVICE_LOWER)
   {
       qscreen = pDesktop.screen(0);
   }
 
  QWidget(qscreen);
}

IFHMIQtGui::IFHMIQtGui(QWidget* parent, GUIDevice device)
{
   QDesktopWidget pDesktop;
   QWidget *qscreen;

   if (device == DEVICE_UPPER)
   {
       qscreen = pDesktop.screen(1);
   }
   else if (device == DEVICE_LOWER)
   {
       qscreen = pDesktop.screen(0);
   }
  
  QWidget(qscreen);
}

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I know that if I pass the QDesktopWidget to my IFHMIQtGui when I contruct the object, the QWidget is displayed on the right monitor. Anyway, the problem is that I need to use QDesktopWidget inside the IFHMIQtGui constructor.

Thank you.

[jpn]

QDesktopWidget *pDesktop = QApplication::desktop();
QRect geometry = pDesktop->availableScreenGeometry(number);
move(geometry.topLeft());

QDesktopWidget *pDesktop = QApplication::desktop();
QRect geometry = pDesktop->availableScreenGeometry(number);
move(geometry.topLeft());

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[tarod]

QDesktopWidget *pDesktop = QApplication::desktop();
QRect geometry = pDesktop->availableScreenGeometry(number);
move(geometry.topLeft());

QDesktopWidget *pDesktop = QApplication::desktop();
QRect geometry = pDesktop->availableScreenGeometry(number);
move(geometry.topLeft());

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I put that code in the constructor, but the QWidget is always displayed on the lowermonitor. I've also changed the "number" variable without success.

[jpn]

Please read: Restoring a Window's Geometry:

On Windows, this is basically storing the result of QWidget::geometry() and calling QWidget::setGeometry() in the next session before calling show(). On X11, this won't work because an invisible window doesn't have a frame yet. The window manager will decorate the window later. When this happens, the window shifts towards the bottom/right corner of the screen depending on the size of the decoration frame. Although X provides a way to avoid this shift, most window managers fail to implement this feature.

A workaround is to call setGeometry() after show().

Maybe you are experiencing this problem?