def start_selection(self, event):

        if event.inaxes != self._axes:
            return False

        xy = data_to_pixel(self._axes, [event.xdata], [event.ydata])
        xi = xy[0, 0]
        yi = xy[0, 1]

        if event.key == SCRUBBING_KEY:
            if not self._roi.defined():
                return False
            elif not self._roi.contains(xi, yi):
                return False

        self._roi_store()

        if event.key == SCRUBBING_KEY:
            self._scrubbing = True
            (xc, yc) = self._roi.get_center()
            self._dx = xc - xi
            self._dy = yc - yi
        else:
            self.reset()
            self._roi.set_center(xi, yi)
            self._roi.set_radius(0.)
            self._xi = xi
            self._yi = yi

        self._mid_selection = True
        self._sync_patch()
dataset/ETHPy150Open glue-viz/glue/glue/core/roi.py/MplCircularROI.start_selection/original