How to set QDockWidget initial (default) size in the app with no central widget (PyQt4)?

Question

I have an app with a lot of QDockWidgets and without central widget. I want to set some of those QDockWidgets initial size (size at application's start), but I don't want to limit their min/max sizes.

How to do it? For example, I need to set initial size 150x75 to one of them. I tried obvious methods (such as QWidget.Resize() relating to dock widget content), but it didn't work at all.

Here is a simplified model of situation:

from PyQt4 import QtCore, QtGui

app = QtGui.QApplication([''])

mw = QtGui.QMainWindow() # mw = MainWindow
mw.setCentralWidget(None)
mw.showMaximized()

mw.dockWdg1 = QtGui.QDockWidget(mw)
mw.content1 = QtGui.QTreeWidget()
mw.dockWdg1.setWidget(mw.content1)
mw.addDockWidget(QtCore.Qt.DockWidgetArea(2), mw.dockWdg1)
mw.dockWdg1.setWindowTitle("1st dock widget")

mw.dockWdg2 = QtGui.QDockWidget(mw)
mw.content2 = QtGui.QTreeWidget()
mw.dockWdg2.setWidget(mw.content2)
mw.addDockWidget(QtCore.Qt.DockWidgetArea(1), mw.dockWdg2)
mw.dockWdg2.setWindowTitle("2nd dock widget")

mw.dockWdg3 = QtGui.QDockWidget(mw)
mw.content3 = QtGui.QTreeWidget()
mw.dockWdg3.setWidget(mw.content3)
mw.addDockWidget(QtCore.Qt.DockWidgetArea(1), mw.dockWdg3)
mw.dockWdg3.setWindowTitle("3rd dock widget")

mw.show()
app.exec_()

Answer 1

The dockwidgets will be incorporated into the layout of the main window, so any attempt to resize them will be ignored.

The standard workaround for this is to create a subclass of the content widget and reimplement its sizeHint:

class TreeWidget(QtGui.QTreeWidget):
    def sizeHint(self):
        return QtCore.QSize(150, 75)

mw.dockWdg2 = QtGui.QDockWidget(mw)
mw.content2 = TreeWidget()
mw.dockWdg2.setWidget(mw.content2)

However, this will only work to the extent that you also carefully manage the sizes of the other dockwidgets. And of course maximiizing the main window is also going to have a impact on the final outcome.

You might also want to consider using QMainWindow.saveState and QMainWindow.restoreState to manage the initial state of your dockwidgets.

Answer 2

Use the fixedSize function, as setFixedWidth/setFixedHeight.

Answer 3

I think reimplementing the sizeHint() function based on MainWindow's size is better than just returning a fixed size.

Source Code

// size hint
QSize RenderWindow::sizeHint() const
{
    float width = MainWindow::instance()->width() * 0.3f;
    float height = MainWindow::instance()->height() * 0.65f;
    return QSize( width, height);
}