view.py 文件源码

def __init__(self, scene=None):
        if scene is None:
            scene = TurtleScene()
        self._scene = scene
        super().__init__(scene)
        transform = QtGui.QTransform(
            1, 0,
            0, -1,  # Revert y, so it uses the standard axis convention in maths
            0, 0
        )
        self.setTransform(transform)
        self._zoomfactor = 1.2

        # This will crash if I put it in the module namespace, probably
        # because the QApplication instance does not exist yet
        _LABEL_HEIGHT = QtGui.QFontMetrics(
            _LABEL_FONT).height() + 2 * _LABEL_PADDING

        w = self._posLabel = QtWidgets.QLabel(self)
        # http://stackoverflow.com/questions/7928519/how-to-make-the-qlabel-background-semi-transparent
        # Fourth parameter in color tuple is alpha: 0-transparent; 255-opaque
        w.setStyleSheet('color: rgba(0, 0, 0, 196); '
                        'background-color: rgba(0, 0, 0, 0);'
                        'padding: %d' % _LABEL_PADDING)
        w.setAlignment(QtCore.Qt.AlignRight)
        w.setFont(_LABEL_FONT)
        w.setGeometry(0, 0, 100, _LABEL_HEIGHT)
        self._updatePosLabelText((0, 0))
        self._updatePosLabelPosition()