How to programatically resize a QMainWindow to its minimum size

Question

When I have a QMainWindow with a grid layout, when resizing it with the mouse, it won't go below some minimum size that's necessary for all the controls in it to show properly. In my app I sometimes programatically hide controls, but then the window remains the same size and the rest of the controls look spread out, with too much space between them. I end up resizing the dialog manually so it doesn't look ugly.

Can I programatically set the dialog's vertical size to this minimum I get when manually resizing after I've hidden controls in it?

Answer 1

This code will do the trick (it resizes only the height):

    QWidget widget;
    widget.resize(widget.width(), widget.minimumHeight());

Answer 2

I have found that resizing the centralWidget in the QMainWindow then resizing the QMainWindow itself does the trick. In other words:

from PyQt4 import QtGui
class MyMainWindow(QtGui.QMainWindow):
    def __init__(self):
        # define some widgets and stuff
    def whenWidgetsAreHidden(self):
        # this method should be triggered when you hide your widgets
        self.centralWidget.adjustSize()
        self.adjustSize()

Note that there are other widgets in the QMainWindowLayout. Per this image from the Qt Documentation, there are also Dock Widgets and other stuff that could be present. I only use the centralWidget so this solution works for me.

Answer 3

There is hierarchy between QLayout::SizeConstraint, QWidget::minimumSizeHint, QWidget::minimumSize, and you can find it in the documentation.

• QWidget::minimumSize is not set by default. When it is, it prevails over QWidget::minimumSizeHint
• QWidget::minimumSizeHint is invalid if the widget is not in a layout (meaning that it can be resized to 0 with the mouse), otherwise use the one defined by the layout.
• QLayout::SizeConstraint holds the default layout behavior of the widgets it *directly * manage. If you nest a layout A within a layout B, all widgets added to A will use its property. Also if a widget W in B define its own layout, then this layout constraints are the one to be applied for the widget W.

Knowing that, follow these steps. It might work, i didn't try :) :

• Set the minimum size of all widgets you use.
• Ensure that the size constraint of all your layouts is set to QLayout::SetDefaultConstraint.