Centralize QTableView in window with vertical spacers - scrollbar

Question

I am trying to create a main window (fixed size) that contains a QTableView, with QSpacerItems above and below, in order to centralise the table (vertically).
(Sorry, can't post an image, apparently).
I have a QVBoxLayout, into which I have a vertical spacer, the QTableView, and another vertical spacer. I've played with all combinations of QSizePolicy for all three widgets, but I cannot get the table to be displayed without scrollbars. (I cannot use Qt.ScrollBarAlwaysOff because they will be needed if the number of items exceeds the main window's size). So the vertical scrollbars on the QTableView are displayed, even though the vertical spacers are absorbing plenty of space between the view and the main window.
I want the vertical spacers to take up the minimum space required above and below the table widget in order to centralise the rows, and the table widget to display as many rows as possible, without scrollbars.

Answer 1

You can subclass QTableView, use QSizePolicy::Fixed in the vertical direction and override sizeHint() to return your preferred vertical height.
Here's a working example (You didn't specify language, so I am going to assume it is Python :-) :
import sys
from PySide import QtCore, QtGui
class MyTableView(QtGui.QTableView):
def __init__(self, parent=None):
super().__init__(parent)
#assume expanding in horizontal direction and fixed in vertica direction
self.setSizePolicy(QtGui.QSizePolicy.Expanding, QtGui.QSizePolicy.Fixed)
def sizeHint(self):
return QtCore.QSize(400, 500) #I allow you to edit that!
class MyApplication(QtGui.QWidget):
def __init__(self, parent=None):
super().__init__(parent)
layout = QtGui.QVBoxLayout()
table_view = MyTableView()
layout.addWidget(table_view)
self.model = QtGui.QStringListModel() #use a string list model for simplicity
table_view.setModel(self.model)
self.strings = ['1', '2', '3']
self.model.setStringList(self.strings) #initialize the model
self.counter = 4
button = QtGui.QPushButton('Add Cell') #this button updates the model and adds cells
button.clicked.connect(self.addCell)
layout.addWidget(button)
self.setLayout(layout)
def addCell(self):
self.strings.append(str(self.counter))
self.counter += 1
self.model.setStringList(self.strings)
app = QtGui.QApplication(sys.argv)
main = MyApplication()
main.show()
sys.exit(app.exec_())