Question

I have just wrote a little example and i can’t manage to make it run.

from PyQt4 import QtGui, QtCore
import sys

class Drawer(QtGui.QWidget):

    def __init__(self, parent=None):
        super(Drawer, self).__init__(parent)
        self.setStyleSheet("QWidget { background-color: %s }" % QtGui.QColor(99, 0, 0).name())

    def mousePressEvent(self, event):
        print 'mouse pressed'
        self.update();

class MyApp(QtGui.QMainWindow):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        self.drawer = Drawer(self)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    myapp = MyApp()
    myapp.show()
    sys.exit(app.exec_())     

widget is not shown (no color, the window is gray) and if i press the mouse no print..

where is my error?

SOLVED: as qiao just point me in a comment, my error is the way to add a widget in the qt4 kind of scenegraph. i thought i had to call the parent in init and that’s all. This is not enogh, i have to add a QLayout and add the childs in it (this is quite obvious: the method addWidget is written only in QLayout and not in QWidget and having a scenegraph system without the possibility of adding new child is quite weird)

Answer 1

You have to set the central widget of the main window to be the drawer. Otherwise the drawer will not attached to the main window.

class MyApp(QtGui.QMainWindow):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        self.drawer = Drawer(self)
        self.setCentralWidget(self.drawer)

After the above fix, you will see mouse press event working properly.

As for the color, setting the stylesheet of QMainWindow is fine, so is setting Drawer to be another widget(like QLineEdit). I don’t know what’s the matter here.