Dial.py

import sys
from PyQt4 import QtGui, QtCore, Qt
import math

class Example(QtGui.QWidget):

    def __init__(self):
        super(Example, self).__init__()

        self.initUI()

    def initUI(self):

        hbox = QtGui.QHBoxLayout(self)
        #dial = QtGui.QPixmap("speedo4.png")

        lbl = QtGui.QLabel(self)


        hbox.addWidget(lbl)
        self.setLayout(hbox)
        self.setGeometry(0, 0,600,600)

        self.move(300, 200)
        self.setWindowTitle('Dial Guage')
        self.show()

    def paintEvent(self, e):
        painter = QtGui.QPainter()
        painter.begin(self)
        dial = QtGui.QPixmap("speedo4.png")

        #painter.drawPixmap(50, 50, 600, 600, dial)

        painter.setRenderHint(painter.Antialiasing)
        rect = e.rect()
        #rect = QtCore.QRect(50,50,600,600)

        gauge_rect = QtCore.QRect(rect)
        size = gauge_rect.size()
        pos = gauge_rect.center()
        gauge_rect.moveCenter( QtCore.QPoint(pos.x()-size.width(), pos.y()-size.height()) )
        gauge_rect.setSize(size*.9)
        gauge_rect.moveCenter(pos)

        refill_rect = QtCore.QRect(gauge_rect)
        size = refill_rect.size()
        pos = refill_rect.center()
        refill_rect.moveCenter( QtCore.QPoint(pos.x()-size.width(), pos.y()-size.height()) )
        # smaller than .9 == thicker gauge
        refill_rect.setSize(size*.9)
        refill_rect.moveCenter(pos)

        painter.setPen(QtCore.Qt.NoPen)

        painter.drawPixmap(rect, dial)

        painter.save()
        grad = QtGui.QConicalGradient(QtCore.QPointF(gauge_rect.center()), 270.0)
        grad.setColorAt(.75, QtCore.Qt.green)
        grad.setColorAt(.5, QtCore.Qt.yellow)
        grad.setColorAt(.1, QtCore.Qt.red)
        painter.setBrush(grad)
        #painter.drawPie(gauge_rect, 225.0*16, self._value*16)
        painter.drawPie(gauge_rect, 225.0*16, -270*1*16)
        painter.restore()

        painter.setBrush(QtGui.QBrush(dial.scaled(rect.size())))
        painter.drawEllipse(refill_rect)

        super(Example,self).paintEvent(e)


        painter.end()


def main():

    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()