How to resize QMainWindow after removing all DockWidgets?

Question

I’m trying to make an application consisting of a QMainWindow, the central widget of which is a QToolBar (it may not be usual, but for my purpose the toolbar’s well suited). Docks are allowed below only. I added a QDockWidget to it, and a QAction on the QToolBar toggles the QDockWidget on and off with removeDockWidget() and restoreDockWidget().

The default size of the QMainWindow is 800 by 24, QToolBar’s maximumHeight is set to 24 too. Right after the removeDockWidget() is called, QMainWindow’s geometry is set back to (0,0,800,24) with setGeometry().

What I want to achieve is to resize the QMainWindow’s height to 24 when the DockWidget’s removed. The setGeometry() seems to work since width and position change accordingly, but funnily enough, the height doesn’t budge. And that’s my problem really :)

What’s the matter you think?

Here is a screen-cast illustrating the issue at hand.

NB: if i create the same scenario using a QWidget rather than QMainWindow, and using a show() or hide() on the child widget, then I can resize the parent with adjustSize() without problem: it seems the problem here above is QMainWindow specific.

Answer 1

Options

a) You can overload sizeHint() a virtual function. Let it return the size you want for your main window.

b) In the main window's constructor you can call setMinimumSize() and setMaximumSize() one after another, both with the the desired main window size. If you keep both same you get a fixed size.

c) Take a look at layout()->setResizeMode(Fixed).

Answer 2

It looks like you misunderstood the meaning of the QMainWindow.sizeHint() method.

According to QWidget.sizeHint() documentation (from which QMainWindow inherits):

This property holds the recommended size for the widget.

If the value of this property is an invalid size, no size is recommended. The default implementation of sizeHint() returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.

To get the actual size of your window, you should use the QMainWindow.geometry() method instead, which gives all the informations about the widget size and position:

win_geo = self.geometry()
win_top = win_geo.top()
win_bottom = win_geo.bottom()
win_left = win_geo.left()
win_right = win_geo.right()
win_width = win_geo.width()
win_height = win_geo.height()