Compass widget

 1 import sys
 2 from PyQt4.QtCore import *
 3 from PyQt4.QtGui import *
 4 
 5 class CompassWidget(QWidget):
 6 
 7  angleChanged = pyqtSignal(float)
 8  
 9  def __init__(self, parent = None):
 10  
 11  QWidget.__init__(self, parent)
 12  
 13  self._angle = 0.0
 14  self._margins = 10
 15  self._pointText = {0: "N", 45: "NE", 90: "E", 135: "SE", 180: "S",
 16  225: "SW", 270: "W", 315: "NW"}
 17  
 18  def paintEvent(self, event):
 19  
 20  painter = QPainter()
 21  painter.begin(self)
 22  painter.setRenderHint(QPainter.Antialiasing)
 23  
 24  painter.fillRect(event.rect(), self.palette().brush(QPalette.Window))
 25  self.drawMarkings(painter)
 26  self.drawNeedle(painter)
 27  
 28  painter.end()
 29  
 30  def drawMarkings(self, painter):
 31  
 32  painter.save()
 33  painter.translate(self.width()/2, self.height()/2)
 34  scale = min((self.width() - self._margins)/120.0,
 35  (self.height() - self._margins)/120.0)
 36  painter.scale(scale, scale)
 37  
 38  font = QFont(self.font())
 39  font.setPixelSize(10)
 40  metrics = QFontMetricsF(font)
 41  
 42  painter.setFont(font)
 43  painter.setPen(self.palette().color(QPalette.Shadow))
 44  
 45  i = 0
 46  while i < 360:
 47  
 48  if i % 45 == 0:
 49  painter.drawLine(0, -40, 0, -50)
 50  painter.drawText(-metrics.width(self._pointText[i])/2.0, -52,
 51  self._pointText[i])
 52  else:
 53  painter.drawLine(0, -45, 0, -50)
 54  
 55  painter.rotate(15)
 56  i += 15
 57  
 58  painter.restore()
 59  
 60  def drawNeedle(self, painter):
 61  
 62  painter.save()
 63  painter.translate(self.width()/2, self.height()/2)
 64  painter.rotate(self._angle)
 65  scale = min((self.width() - self._margins)/120.0,
 66  (self.height() - self._margins)/120.0)
 67  painter.scale(scale, scale)
 68  
 69  painter.setPen(QPen(Qt.NoPen))
 70  painter.setBrush(self.palette().brush(QPalette.Shadow))
 71  
 72  painter.drawPolygon(
 73  QPolygon([QPoint(-10, 0), QPoint(0, -45), QPoint(10, 0),
 74  QPoint(0, 45), QPoint(-10, 0)])
 75  )
 76  
 77  painter.setBrush(self.palette().brush(QPalette.Highlight))
 78  
 79  painter.drawPolygon(
 80  QPolygon([QPoint(-5, -25), QPoint(0, -45), QPoint(5, -25),
 81  QPoint(0, -30), QPoint(-5, -25)])
 82  )
 83  
 84  painter.restore()
 85  
 86  def sizeHint(self):
 87  
 88  return QSize(150, 150)
 89  
 90  def angle(self):
 91  return self._angle
 92  
 93  @pyqtSlot(float)
 94  def setAngle(self, angle):
 95  
 96  if angle != self._angle:
 97  self._angle = angle
 98  self.angleChanged.emit(angle)
 99  self.update()
 100  
 101  angle = pyqtProperty(float, angle, setAngle)
 102 
 103 
 104 if __name__ == "__main__":
 105 
 106  app = QApplication(sys.argv)
 107  
 108  window = QWidget()
 109  compass = CompassWidget()
 110  spinBox = QSpinBox()
 111  spinBox.setRange(0, 359)
 112  spinBox.valueChanged.connect(compass.setAngle)
 113  
 114  layout = QVBoxLayout()
 115  layout.addWidget(compass)
 116  layout.addWidget(spinBox)
 117  window.setLayout(layout)
 118  
 119  window.show()
 120  sys.exit(app.exec_())