[FIXED] Painting filled ellipse with Pyside

Issue

I'm trying to paint an solid colored ellipse in pyside and I'm getting an unexpected black line around the outside and I'm also not getting what appears to be a smooth circular shape? Some colors are not showing up as well.

What am I doing wrong here?

import sys
from PySide import QtGui, QtCore

class Example(QtGui.QDialog):
    def __init__(self, parent=None):
        super(Example, self).__init__(parent)
        self.resize(200, 50)
        self.initUI()

    def initUI(self):
        self.ui_list = QtGui.QComboBox()
        grid = QtGui.QVBoxLayout()
        grid.addWidget(self.ui_list)
        self.setLayout(grid)
        self.populate_list()

    def populate_list(self):
        colors = {
            'White': QtCore.Qt.white,  
            'Black': QtCore.Qt.black,  
            'Red': QtCore.Qt.red,
            'Green': QtCore.Qt.green,   
            'Blue': QtCore.Qt.blue,
            'Cyan': QtCore.Qt.cyan,
            'Magenta': QtCore.Qt.magenta,
            'Yellow': QtCore.Qt.yellow, 
            'Gray': QtCore.Qt.gray,
            'Orange': QtGui.QColor(255,128,0)
        }
        px = QtGui.QPixmap(12,12)

        for key, val in sorted(colors.items()):
            px.fill(QtCore.Qt.transparent)
            painter = QtGui.QPainter(px)
            painter.setBrush(QtGui.QColor(val))
            painter.drawEllipse(0,0,12,12)
            self.ui_list.addItem(QtGui.QIcon(px), key) 

def main():
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    ex.show()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Solution

Just looking at the approved answer, It looks to me like the outline is black and setting a larger pixmap is making the issue less visible. I would be better to set the stroke color instead. Also, making a pixmap larger in order to get a nicer looking circle is unnecessary if you turn on antialiasing explicitly.

...

for key, val in sorted(colors.items()):
    # a small pixmap size
    size = 32
    px = QtGui.QPixmap(size,size)
    px.fill(QtCore.Qt.transparent)
    painter = QtGui.QPainter(px)
    # turn on Antialiasing
    painter.setRenderHints(QtGui.QPainter.Antialiasing, True)
    # set the brush and pen to the same color
    painter.setBrush(QtGui.QColor(val))
    painter.setPen(QtGui.QColor(val))
    painter.drawEllipse(px.rect())
    painter.end()
    self.ui_list.addItem(QtGui.QIcon(px), key) 

Answered By - user11167350