QWidget::setLayout: Attempting to set QLayout "" on MainWindow "", which already has a layout
I'm making an application in PyQt4 and this is my code so far:
import sys
from PyQt4 import QtGui, QtCore
class MainWindow(QtGui.QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.initUi()
def initUi(self):
self.setWindowTitle('Main Menu')
self.setFixedSize(1200, 625)
self.firstWidgets()
self.show()
def firstWidgets(self):
self.vbox1 = QtGui.QVBoxLayout()
self.task1 = QtGui.QLabel('Check 1', self)
self.task1CB = QtGui.QCheckBox(self)
self.hbox1 = QtGui.QHBoxLayout()
self.hbox1.addWidget(self.task1)
self.hbox1.addWidget(self.task1CB)
self.vbox1.addLayout(self.hbox1)
self.setLayout(self.vbox1)
def main():
application = QtGui.QApplication(sys.argv)
gui = MainWindow()
sys.exit(application.exec_())
if __name__=='__main__':
main()
My problem is in MainWindow.firstWidgets()
. I try to set a layout but I get an error even though that's my first time using .setLayout
for that form, which confuses me.
QWidget::setLayout: Attempting to set QLayout "" on MainWindow "", which already has a layout
Solution 1:
You can't set a QLayout
directly on the QMainWindow
. You need to create a QWidget
and set it as the central widget on the QMainWindow
and assign the QLayout
to that.
wid = QtGui.QWidget(self)
self.setCentralWidget(wid)
layout = QtGui.QVBoxLayout()
wid.setLayout(layout)
NOTE: This is for Qt4 -- see the other answer on this question for the Qt5 updated code.
Solution 2:
Just an update to Brenden Abel's answer:
QWidget and QVBoxLayout (for Python3, PyQt5) are now contained in the PyQt5.QtWidgets module and not the PyQt5.QtGui module.
So updated code:
wid = QtWidgets.QWidget(self)
self.setCentralWidget(wid)
layout = QtWidgets.QVBoxLayout()
wid.setLayout(layout)
Solution 3:
This is an example using PyQt5
import sys
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QPushButton, QWidget
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle('My App')
# Cannot set QxxLayout directly on the QMainWindow
# Need to create a QWidget and set it as the central widget
widget = QWidget()
layout = QVBoxLayout()
b1 = QPushButton('Red' ); b1.setStyleSheet("background-color: red;")
b2 = QPushButton('Blue' ); b2.setStyleSheet("background-color: blue;")
b3 = QPushButton('Yellow'); b3.setStyleSheet("background-color: yellow;")
layout.addWidget(b1)
layout.addWidget(b2)
layout.addWidget(b3)
widget.setLayout(layout)
self.setCentralWidget(widget)
def main():
app = QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()