spinner_advanced.py 文件源码

def get_position(self, delta):
        """Update the spinner position after the specified delta (in seconds)
        has elapsed.  Will return the new spinner position, a continuous value
        from 0...<10.
        """
        # Increment elapsed time and compute the current velocity after a
        # decay of the initial velocity.
        self._elapsed += delta
        current_velocity = self._velocity*math.pow(self._decay, self._elapsed)
        # Update position based on the current_velocity and elapsed time.
        self._position += current_velocity*delta
        # Make sure the position stays within values that range from 0 to <10.
        self._position = math.fmod(self._position, 10.0)
        if self._position < 0.0:
            self._position += 10.0
        return self._position


# Define animation classes.  Each animation needs to have an update function
# which takes in the current spinner position and a selected primary and
# secondary color (3-tuple of RGB bytes) and will render a frame of spinner
# animation.