can't calla function inside paint event

Question

import sys, csv
from PySide import QtGui, QtCore
from mainStrato import *

X_START = 10
Y_START = 15
MAX_WIDTH = 1350
MAX_LENGH = 1650
ZOOM = 2.5
WIDTH_PEZZO = 150
LENGH_PEZZO = 600
CENTER_OFFSET_X = 15
CENTER_OFFSET_Y = 0

class Strato(QtGui.QMainWindow, Ui_MainWindow):
    #Apre il file CSV e copia le singole righe in una lista

    def __init__(self, parent=None):
      super(Strato, self).__init__(parent)
      self.setupUi(self)

    def paintEvent(centralwidget, e):

        qp = QtGui.QPainter()
        qp.begin(centralwidget)
    print "paint event"
    qp.end()
        self.drawRectangles(qp)

    def drawRectangles(self, qp):

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d4d4d4')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(200, 0, 0))
        coordCarro = QtCore.QRectF(X_START, Y_START, MAX_WIDTH/ZOOM, MAX_LENGH/ZOOM)
        qp.drawRect(coordCarro)


if __name__ == "__main__":

    app = QtGui.QApplication(sys.argv)
    window = Strato()
    window.show()
    sys.exit(app.exec_())

mainstrato is a file generated from pyside-uic . I got an error Object not defined on calling self.drawRectangles or any other function in Strato called inside paint event? If I copy the drawRectangles code in paint event it works!

Suggestion? What's wrong?

Answer 1

You are missing self in the paintEvent definition - and I assume that centralwidget is part of your UI class, so that should be accessible through self.centralwidget (since you are inheriting from your UI class). Besides self , paintEvent has only one parameter, the event object. Also, you must not call qp.end() before you have drawn your rectangles. Finally, you need to properly indent your code - but that could also be a copy&paste issue when posting the question. Try

def paintEvent(self, e):
    qp = QtGui.QPainter()
    qp.begin(self.centralwidget)
    print "paint event"
    self.drawRectangles(qp)
    qp.end()

And, finally, you should not paint on other widgets from within one Widget's paintEvent . Instead, subclass QWidget and overide its paint event. The following sscce works (all non-relevant code removed):

#!/usr/bin/python

import sys
from PySide import QtGui, QtCore

X_START = 10
Y_START = 15
MAX_WIDTH = 1350
MAX_LENGH = 1650
ZOOM = 2.5
WIDTH_PEZZO = 150
LENGH_PEZZO = 600
CENTER_OFFSET_X = 15
CENTER_OFFSET_Y = 0

class PaintWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(PaintWidget, self).__init__(parent)

    def paintEvent(self, e):
        qp = QtGui.QPainter(self)
        print("paint event")
        self.drawRectangles(qp)

    def drawRectangles(self, qp):

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d4d4d4')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(200, 0, 0))
        coordCarro = QtCore.QRectF(X_START, Y_START, MAX_WIDTH/ZOOM, MAX_LENGH/ZOOM)
        qp.drawRect(coordCarro)

class Strato(QtGui.QMainWindow):

    def __init__(self, parent=None):
        super(Strato, self).__init__(parent)
        self.centralwidget = PaintWidget(self)
        self.setCentralWidget(self.centralwidget)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    window = Strato()
    window.show()
    sys.exit(app.exec_())