Is it possible to move main menubar down?

[gfunk]

I want to place some graphic/banner above the main QMenuBar provided by QMainWindow. Does anyone know a way to do this? I tried setting the x,y geometry in QMenubar and QMainWindow, but it didn't change a thing - it seems the menubar is stuck in the top left-hand corner of the window.

Has anyone ever tried subclassing QMenuBar to do this? Or is there a different way I should go about this...

[wysota]

The menu bar is probably positioned using a layout. You can peek at the sources of QMainWindow class to look for the layout and how it is used and then gain access to the layout (for example by calling it by name, if necessary) and insert an additional widget in a place you want it in.

[gfunk]

Interesting... I tried accessing the QMainWindowLayout object and tried adding buttons to it, but it would just crash. Ick... I wonder if anyone has actually delved into this. the QMainWindowLayout class looks like a monster, 2500 lines... all that docking widget support code...

Alternatively, maybe it would be easier to just re-implement the menubar into a dialog so that it can be embedded elsewhere on the main window. I wonder if QToolButtons with just text inside, placed on a QToolBar, will look sufficiently similar to the menubar...

[wysota]

Not a very good idea. I would stick to the layout thing. Just try to correct your code, I'm sure it'll work.

[gfunk]

Well, here's what I quickly tried to come up with: (there's a lot more code that I had to expose in order to get into QMainWindowPrivate - included below)

QMainWindowPrivate* p = reinterpret_cast<QMainWindowPrivate*>(d_ptr);
QLayoutItem *li0 = p->layout->takeAt(0);
QLayoutItem *li1 = p->layout->takeAt(0);
QLayoutItem *li2 = p->layout->takeAt(0);
p->layout->addWidget(new QPushButton);
p->layout->addWidget(li0->widget());
p->layout->addWidget(li1->widget());
p->layout->addWidget(li2->widget());

QMainWindowPrivate* p = reinterpret_cast<QMainWindowPrivate*>(d_ptr);
QLayoutItem *li0 = p->layout->takeAt(0);
QLayoutItem *li1 = p->layout->takeAt(0);
QLayoutItem *li2 = p->layout->takeAt(0);
p->layout->addWidget(new QPushButton);
p->layout->addWidget(li0->widget());
p->layout->addWidget(li1->widget());
p->layout->addWidget(li2->widget());

To copy to clipboard, switch view to plain text mode 

Naturally it doesn't crash right away; probably when it's drawing. Wondering if this is the right way to go. Seems ugly to have to remove the previous items and then re-add them after my pushbutton (but I suppose it must be done that way since no insertWidget method exists). Just wondering if this is the right way to go...

(ugliness included to get this to compile):

#include "C:/Qt/4.1.4/src/gui/widgets/qmainwindowlayout_p.h"
#include "C:/Qt/4.1.4/src/gui/kernel/qwidget_p.h"
class QMainWindowPrivate : public QWidgetPrivate
{
Q_DECLARE_PUBLIC(QMainWindow)
public:
inline QMainWindowPrivate()
: layout(0), toolButtonStyle(Qt::ToolButtonIconOnly)
{ }
QMainWindowLayout *layout;
QSize iconSize;
bool explicitIconSize;
Qt::ToolButtonStyle toolButtonStyle;
void init();
};

#include "C:/Qt/4.1.4/src/gui/widgets/qmainwindowlayout_p.h"
#include "C:/Qt/4.1.4/src/gui/kernel/qwidget_p.h"
class QMainWindowPrivate : public QWidgetPrivate
{
Q_DECLARE_PUBLIC(QMainWindow)
public:
inline QMainWindowPrivate()
: layout(0), toolButtonStyle(Qt::ToolButtonIconOnly)
{ }
QMainWindowLayout *layout;
QSize iconSize;
bool explicitIconSize;
Qt::ToolButtonStyle toolButtonStyle;
void init();
};

To copy to clipboard, switch view to plain text mode 

[wysota]

I would try to reach proper objects by calling them by name. They are all QObject and as such they are accessible through QObject::findChildren().

[gfunk]

Ah, you're right, I can get the layout much easier... even calling layout() works. But I still can't seem to add anything to that QMainWindowLayout.

[wysota]

Did you try simply using QMainWindow::setMenuWidget() and passing a complex widget composed of your custom data and a QMenuBar laid out vertically?

+-------------------+
|QWidget w. v-layout|
| +---------------+ |
| | CUSTOM WIDGET | |
| +---------------+ |
| |    QMenuBar   | |
| +---------------+ |
+-------------------+

+-------------------+
|QWidget w. v-layout|
| +---------------+ |
| | CUSTOM WIDGET | |
| +---------------+ |
| |    QMenuBar   | |
| +---------------+ |
+-------------------+

To copy to clipboard, switch view to plain text mode 

Edit: Note that it's available since Qt4.2. In earlier versions you have to stick with mangling with the layout directly.

[gfunk]

Oh wow! I was using 4.1 and had no idea they added that to 4.2. Thanks, I will have to check that out.

[jpn]

This should do the trick in Qt 4.1:

menuBar()->setParent(statusBar());

menuBar()->setParent(statusBar());

To copy to clipboard, switch view to plain text mode 

I can't assure it won't break something but it's worth try..

[gfunk]

This should do the trick in Qt 4.1:

menuBar()->setParent(statusBar());

menuBar()->setParent(statusBar());

To copy to clipboard, switch view to plain text mode 

Interesting. I tried it and noticed that it could make the menubar take up the window space of any widget that I called setParent() on. Unfortunately, the menubar QAction's can't pop up any dialogs, ending up in crash. Ah well, was definitely worth the try.