乌龟图形随机游走 pause/resume 函数

Question

菜鸟来啦！我修改了我正在参加的在线课程中的随机游走作业，并且我正在尝试创建一个函数来暂停程序，并在再次调用时恢复它。它目前暂停了，但我似乎无法让它恢复；或者准确地说，一旦暂停我就无法得到任何反应——就好像屏幕停止监听事件一样。

我已经试过了：

为恢复创建一个单独的函数 - 如果我在暂停之前调用该函数，但在暂停之后我无法调用它，该函数就可以工作
我可以为 if go 条件添加一个 else 子句，其中我将变量声明为 screen.textinput 并根据输入程序将继续或结束，但我希望它像暂停一样简单。
我尝试在 if go 中断后添加一个 screen.listen() 调用作为 else 子句，但它似乎不起作用...
我尝试将 go=False 设置为默认值，然后通过调用函数将其设置为 True 来启动它，但这也不起作用。

P.S: 我是编程新手，所以如果您有进一步的评论和建议，我将不胜感激。

非常感谢！

在相关行中附上我的代码注释：

from turtle import Turtle, colormode, Screen
from random import choice, randint

colormode(255)
tim = Turtle('circle')
tim.speed('fastest')
tim.width(10)
screen = Screen()
go = True  # Boolean to initialize line 31


def pause():  # Currently it pauses, but doesn't resume.
    """Pause the program by setting go to False, and resume it if it was paused"""
    global go
    if go:
        go = False
    else:
        go = True


def random_color():
    """Return a random color"""
    r = randint(0, 255)
    g = randint(0, 255)
    b = randint(0, 255)
    generated_color = (r, g, b)
    return generated_color


screen.listen()  # Starts listening for events
screen.onkey(fun=pause, key='p')  # Event - when the 'p' key is pressed, the 'pause' function is called.

while True:  # Outer loop to prevent the code from ending when 'go' is set to False by pressing 'p' the first time
    if go:  # As default is True, after pausing can't restart it...
        if 200 > tim.xcor() > -200 and 200 > tim.ycor() > -200:
            tim.color(random_color())
            tim.forward(choice(range(50)))
            tim.setheading(choice(range(360)))
        else:
            tim.goto(0, 0)

Answer 1

问题在于，在您的实现中，当 go 为 False 时，没有函数运行获取键盘事件（因为您不是运行主事件循环）。一种不太优雅的修复方法是在 go == False 时添加一个虚拟操作。将您的最终循环更改为：

while True:  # Outer loop to prevent the code from ending when 'go' is set to False by pressing 'p' the first time
    if go:  # As default is True, after pausing can't restart it...
        if 200 > tim.xcor() > -200 and 200 > tim.ycor() > -200:
            tim.color(random_color())
            tim.forward(choice(range(50)))
            tim.setheading(choice(range(360)))
        else:
            tim.goto(0, 0)
    else:
        tim.setheading(0)

它会起作用。

另一种（更好的）方法是使用事件来移动乌龟。在下面的变体中，我使用 screen.ontimer 方法在给定时间后调用 move 函数。在每次调用 move 之后，它会在一段时间后（在示例中为 50 毫秒）将自身重新安排到运行。这样，你总是有一个事件循环运行宁和接收键盘事件。

from turtle import Turtle, colormode, Screen
from random import choice, randint

colormode(255)
tim = Turtle('circle')
tim.speed('fastest')
tim.width(10)
screen = Screen()
go = True  # Boolean to initialize line 31


def pause():  # Currently it pauses, but doesn't resume.
    """Pause the program by setting go to False, and resume it if it was paused"""
    global go
    if go:
        go = False
    else:
        go = True


def random_color():
    """Return a random color"""
    r = randint(0, 255)
    g = randint(0, 255)
    b = randint(0, 255)
    generated_color = (r, g, b)
    return generated_color

def move():
    if go:  # As default is True, after pausing can't restart it...
        if 200 > tim.xcor() > -200 and 200 > tim.ycor() > -200:
            tim.color(random_color())
            tim.forward(choice(range(50)))
            tim.setheading(choice(range(360)))
        else:
            tim.goto(0, 0)
    screen.ontimer(fun=move, t=50)   # Move every 0.05 s

screen.listen()  # Starts listening for events
screen.onkey(fun=pause, key='p')  # Event - when the 'p' key is pressed, the 'pause' function is called.
screen.ontimer(fun=move, t=0)   # Schedule the first movement
screen.mainloop()

乌龟图形随机游走 pause/resume 函数

Random walk on turtle graphics pause/resume function

python

turtle-graphics