在海龟图形中，可以实现注册多个按键来触发所需的操作。一个常见的示例是，当同时按下向上和向右箭头键时，让海龟沿对角线移动。
请考虑以下代码片段作为起点：
<code class="python">import turtle
flynn = turtle.Turtle()
win = turtle.Screen()
win.bgcolor("LightBlue")
flynn.pensize(7)
flynn.pencolor("lightBlue")
win.listen()
def Up():
flynn.setheading(90)
flynn.forward(25)
def Down():
flynn.setheading(270)
flynn.forward(20)
def Left():
flynn.setheading(180)
flynn.forward(20)
def Right():
flynn.setheading(0)
flynn.forward(20)
def upright():
flynn.setheading(45)
flynn.forward(20)
win.onkey(Up, "Up")
win.onkey(Down,"Down")
win.onkey(Left,"Left")
win.onkey(Right,"Right")</code>虽然此代码允许您执行单独的按键操作，它不适合同时按下按键进行对角移动。
另一种方法是采用排队事件系统。按键事件不是在按键时直接执行操作，而是存储在队列中。然后，计时器定期检查队列并执行排队的操作。这种方法允许捕获和组合多个按键。
以下代码演示了这种替代方法：
<code class="python">from turtle import Turtle, Screen
win = Screen()
flynn = Turtle('turtle')
def process_events():
events = tuple(sorted(key_events))
if events and events in key_event_handlers:
(key_event_handlers[events])()
key_events.clear()
win.ontimer(process_events, 200)
def Up():
key_events.add('UP')
def Down():
key_events.add('DOWN')
def Left():
key_events.add('LEFT')
def Right():
key_events.add('RIGHT')
def move_up():
flynn.setheading(90)
flynn.forward(25)
def move_down():
flynn.setheading(270)
flynn.forward(20)
def move_left():
flynn.setheading(180)
flynn.forward(20)
def move_right():
flynn.setheading(0)
flynn.forward(20)
def move_up_right():
flynn.setheading(45)
flynn.forward(20)
def move_down_right():
flynn.setheading(-45)
flynn.forward(20)
def move_up_left():
flynn.setheading(135)
flynn.forward(20)
def move_down_left():
flynn.setheading(225)
flynn.forward(20)
key_event_handlers = { \
('UP',): move_up, \
('DOWN',): move_down, \
('LEFT',): move_left, \
('RIGHT',): move_right, \
('RIGHT', 'UP'): move_up_right, \
('DOWN', 'RIGHT'): move_down_right, \
('LEFT', 'UP'): move_up_left, \
('DOWN', 'LEFT'): move_down_left, \
}
key_events = set()
win.onkey(Up, "Up")
win.onkey(Down, "Down")
win.onkey(Left, "Left")
win.onkey(Right, "Right")
win.listen()
process_events()
win.mainloop()</code>使用这种方法，当同时按下向上和向右箭头键时，move_up_right函数被触发，导致海龟沿对角线方向移动。
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