[FIXED] custom paint() not working with QLayout.setSpacing()

Issue

I am struggling to understand something seemingly simple:

I have a custom widget subclassing from QPushButton, multiple instances of which I am laying out in a QGridLayout(). The moment I add a paint() function and draw a background color to fill the button's rect() the layout's spacing does not seem to have an effect anymore. Here is a screen shot to show what I mean:

This shows default QPushButtons that obey the layout's spacing and my custom "buttons" that don't. I'm sure I just need to (re)implement something in my CustomButton but can't find what it is. I tried setting contentMargins to no avail.

What am I missing? Maybe I need to not fill self.rect() but something else? Here is the example code that produces above screen shot:

import sys
from PySide.QtGui import *
from PySide.QtCore import *
class CustomButton(QPushButton):
    def __init__(self, tool, icon=None, parent=None):
        super(CustomButton, self).__init__(parent)
        self.setSizePolicy(QSizePolicy.Expanding,  QSizePolicy.Fixed)
        self.setMinimumWidth(200)
        self.frameGeometry()

    def paintEvent(self, event):
        painter = QPainter(self)
        bgColor  = QColor(60, 60, 60)
        painter.fillRect(self.rect(), bgColor)

app = QApplication(sys.argv)
mainWindow = QWidget()
grid = QGridLayout()
grid.setSpacing(10)
mainWindow.setLayout(grid)
for i in xrange(4):
    btn1 = CustomButton('A')
    btn2 = QPushButton('B')
    grid.addWidget(btn1, 0, i)
    grid.addWidget(btn2, 1, i)

mainWindow.show()
sys.exit(app.exec_())

Solution

so a solution seems to be to manually adjust self.rect() to be a bit smaller, though I don't understand why this is necessary as I thought that's what the layout's spacing is for:

def paintEvent(self, event):
    rect = self.rect()
    rect.adjust(5,5,-5,-5)
    painter = QPainter(self)
    bgColor = QColor(60, 60, 60)
    painter.fillRect(rect, bgColor)

This will give me the spacing I need. If anybody can shed light on whether this is a bug or a feature I'd be quite grateful.

Answered By - Frank Rueter