xdot.py 文件源码

def __init__(self, dot_widget, target_x, target_y):
        MoveToAnimation.__init__(self, dot_widget, target_x, target_y)
        self.source_zoom = dot_widget.zoom_ratio
        self.target_zoom = self.source_zoom
        self.extra_zoom = 0

        middle_zoom = 0.5 * (self.source_zoom + self.target_zoom)

        distance = math.hypot(self.source_x - self.target_x,
                              self.source_y - self.target_y)
        rect = self.dot_widget.get_allocation()
        visible = min(rect.width, rect.height) / self.dot_widget.zoom_ratio
        visible *= 0.9
        if distance > 0:
            desired_middle_zoom = visible / distance
            self.extra_zoom = min(0, 4 * (desired_middle_zoom - middle_zoom))