python qt : automatically resizing main window to fit content - qt

Question

I have a main window which contains a main widget, to which a vertical layout is set. To the layout is added a QTableWidget only (for the moment).
When I start the application and call show on the main_window, only part of the QTableWidget is shown. I can extend the window manually to see it all, but I would like the window to have its size nicely adapted to the size of the QTableWidget.
Googling the question found a lot of posts on how to use resize to an arbitrary size, and call to resize(int) works fine, but this is not quite what I am asking
Lots of other posts are not explicit enough, e.g "use sizePolicy" or "use frameGeometry" or "use geometry" or "use sizeHint". I am sure all of them may be right, but an example on how to would be awesome.

Answer 1

You can do something like this, from within your MainWindow after placing all the elements you need in the layout:
self.setFixedSize(self.layout.sizeHint())
This will set the size of the MainWindow to the size of the layout, which is calculated using the size of widgets that are arranged in the layout.

Answer 2

I think overriding sizeHint() on the QTableWidget is the key:
import sys
from PyQt5.QtCore import QSize
from PyQt5.QtWidgets import QApplication, QMainWindow, QTableWidget
class Table(QTableWidget):
def sizeHint(self):
horizontal = self.horizontalHeader()
vertical = self.verticalHeader()
frame = self.frameWidth() * 2
return QSize(horizontal.length() + vertical.width() + frame,
vertical.length() + horizontal.height() + frame)
class Main(QMainWindow):
def __init__(self, parent=None):
super(Main, self).__init__(parent)
top = Table(3, 5, self)
self.setCentralWidget(top)
if __name__ == '__main__':
app = QApplication(sys.argv)
main = Main()
main.show()
sys.exit(app.exec_())

Answer 3

You can use sizeHint() but not as stated in the other answers. sizeHint() returns a QSize object with a width and height. Let's say you have a main window mainWindow and a widget inside it called content. If your resizing involves content height to get bigger, you can fit the mainWindow to it like this:
mainWindow.resize(mainWindow.sizeHint().width,
mainWindow.size().height() + content.sizeHint().height());

Answer 4

Old but i experienced this a while back and seeing how the answers here didn't exactly work for me.
Here's what i did:
Please make sure you have the central widget for the 'mainwindow' set properly and the parent of the layout is the central widget,
Then set a sizepolicy for the mainwindow/widget as you wish.
from PyQt5 import QtCore, QtGui, QtWidgets
import sys
class RandomWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(RandomWidget, self).__init__(parent)
self.layout = QtWidgets.QVBoxLayout()
self.setLayout(self.layout)
self.ui()
self.layout.addWidget(self.table)
self.layout.addWidget(self.table2)
def ui(self):
self.table = QtWidgets.QTableWidget()
self.table.setMinimumSize(800,200)
self.table2 = QtWidgets.QTableWidget()
class Mainwindow(QtWidgets.QMainWindow):
def __init__(self):
self.widget = None
super(Mainwindow, self).__init__()
self.setWindowTitle('test')
def ui(self):
self.setCentralWidget(self.widget)
self.show()
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
Window = Mainwindow()
Window.widget = RandomWidget(Window)
Window.ui()
sys.exit(app.exec_())