I am working on the Analog Clock exercise and I am having a hard time getting the clock to animate. (EDIT: I made the clock animate by redrawing it every second but I still want to know if I can rotate a line without redrawing it).

Basically, my issue is that to animate the second hand of a clock (say), I would need to move ONE of the hand's endpoints and then redraw the line to reflect that.

Although Zelle's graphics library gives a natural way to translate a point or a line and redraw it on the screen (self.move(dx, dy)), there seems to be no natural way to redraw a line by moving one of its endpoints; even changing the endpoint does not redraw the line. Is there a natural way to do what I want?

Question

I am working on the Analog Clock exercise and I am having a hard time getting the clock to animate.  (EDIT:  I made the clock animate by redrawing it every second but I still want to know if I can rotate a line without redrawing it).

Basically, my issue is that to animate the second hand of a clock (say), I would need to move ONE of the hand's endpoints and then redraw the line to reflect that.

Although Zelle's graphics library gives a natural way to translate a point or a line and redraw it on the screen (self.move(dx, dy)), there seems to be no natural way to redraw a line by moving one of its endpoints; even changing the endpoint does not redraw the line.  Is there a natural way to do what I want?

anonymous · Answer

As a specific example, imagine that I have the line 
pencil = Line(Point(0, 0), Point(100, 0)) drawn to the screen
and I want to replace pencil with a line joining Point(0, 0) to Point(100, 5).
I could try pencil.move(0, 5), but that would simply replace the line with a line joining Point(0, 5) to Point(100, 5), which is not what I want.

theraggedydoctor · Answer

BRUH