Tkinter 中的“停止”按钮

Question

我正在尝试让海龟动画以按钮开始并以按钮停止。 从按钮开始很容易，但我似乎无法找出停止按钮？ 到目前为止，这是我的代码：

import turtle
import tkinter as tk
def start():
    t.forward(100)
    t.right(90)
    t.forward(100)
    t.left(90)
    t.forward(100)
    t.right(90)
    t.forward(100)
    t.right(90)
    t.forward(100)

def stop():
    t.stop

def clear():
    canvas.delete("all")

root = tk.Tk()
canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)

tk.Button(text = "Start", command = start).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)

root.mainloop()

清除按钮也有效，但之后开始按钮不再有效。 如果有人也可以帮助我。

感谢@Mike - SMT 帮助我处理此代码。 这是经过编辑且功能齐全的代码：

import turtle
import tkinter as tk


def start(turtle_object, draw_path):
    global tracker, start_ndex, end_ndex, started
    tracker = False
    if started == False:
        started = True
        for i in range(start_ndex, end_ndex):
            if tracker == False and i <= end_ndex:
                pth = draw_path[i]
                if pth[0] == "f":
                    turtle_object.forward(pth[1])
                elif pth[0] == "r":
                    turtle_object.right(pth[1])
                elif pth[0] == "l":
                    turtle_object.left(pth[1])
                start_ndex += 1


running = True

def stop():
    global tracker, started
    tracker = True
    started = False

def clear():
    global t, tracker, started, start_ndex
    t.reset()
    start_ndex = 0
    started = False
    t = turtle.RawTurtle(canvas)


root = tk.Tk()
tracker = False
start_ndex = 0
started = False # added this tracking variable to prevent issues with     spamming the start button.

draw_path = [["f", 100], ["r", 90], ["f", 100], ["l", 90], ["f", 100], ["r", 90], ["f", 100], ["r", 90], ["f", 100]]


end_ndex = len(draw_path)

canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)
tk.Button(text = "Start", command = lambda: start(t, draw_path)).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)
root.mainloop()

Answer 1

除非您在绘制的每条线之间提供检查器，否则您无法停止每个绘制语句。

下面的代码只是一个粗略的模型，你可以做一些事情来检查跟踪变量，用于告诉它不再绘制新线。

您可以做的最接近停止绘图的事情是这样的：

import turtle
import tkinter as tk

def start():
    global tracker
    tracker = False
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.left(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)


def stop():
    global tracker
    tracker = True

def clear():
    canvas.delete("all")

root = tk.Tk()
tracker = False
canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)

tk.Button(text = "Start", command = start).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)

root.mainloop()

这至少会在每条线之后停止绘制，但您不能停止绘制中线。

只是为了好玩，如果我们添加一些跟踪变量并使用一些更清晰的逻辑，我们就可以开始、停止和重新开始。

更新：从@cdlane 下面的评论中，我添加了附加跟踪并更新了清除功能。 这应该允许启动停止启动而不会出现问题，并且还能够清除该字段。

import turtle
import tkinter as tk

def start(turtle_object, draw_path):
    global tracker, start_ndex, end_ndex, started
    tracker = False
    if started == False:
        started = True
        for i in range(start_ndex, end_ndex):
            if tracker == False and i <= end_ndex:
                pth = draw_path[i]
                if pth[0] == "f":
                    turtle_object.forward(pth[1])
                elif pth[0] == "r":
                    turtle_object.right(pth[1])
                elif pth[0] == "l":
                    turtle_object.left(pth[1])
                start_ndex += 1

def stop():
    global tracker, started
    tracker = True
    started = False

def clear():
    global t, tracker, started, start_ndex
    canvas.delete("all")
    tracker = False
    start_ndex = 0
    started = False
    t = turtle.RawTurtle(canvas)

root = tk.Tk()
tracker = False
start_ndex = 0
started = False # added this tracking variable to prevent issues with spamming the start button.

draw_path = [["f", 100], ["r", 90], ["f", 100], ["l", 90], ["f", 100], ["r", 90], ["f", 100], ["r", 90], ["f", 100]]


end_ndex = len(draw_path)

canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)
tk.Button(text = "Start", command = lambda: start(t, draw_path)).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)
root.mainloop()

Answer 2

我同意@Mike-SMT 回答中的想法，但我会以不同的方式进行。 海龟和它的控件对我来说看起来很像一个 Python 生成器，所以我把它改成了这样。 海龟沿着一条路径移动，一次一个像素，产生可能返回也可能不返回的控制权。 或者它可能会耗尽其路径并停止迭代：

import tkinter as tk
from turtle import RawTurtle

PATH = [(100.00, 0.00), (100.00, -100.00), (200.00, -100.00), (200.00, -200.00), (100.00, -200.00)]

def run():
    for position in PATH:
        turtle.setheading(turtle.towards(position))

        while turtle.distance(position) > 1:
            turtle.forward(1)
            yield

def start():
    global generator, running

    running = True

    while running:
        try:
            next(generator)

        except ValueError:  # user clicked start but already running
            return

        except TypeError:  # new run
            turtle.reset()
            generator = run()

        except StopIteration:  # end of complete run
            generator = None
            running = False
            break

def stop():
    global running
    running = False

def clear():
    global generator
    turtle.reset()
    generator = None

root = tk.Tk()
canvas = tk.Canvas(width=500, height=500)
canvas.pack()

turtle = RawTurtle(canvas, "turtle")

running = True
generator = None

tk.Button(text="Start", command=start).pack(side=tk.LEFT, expand=tk.TRUE)
tk.Button(text="Stop", command=stop).pack(side=tk.LEFT, expand=tk.TRUE)
tk.Button(text="Clear", command=clear).pack(side=tk.LEFT, expand=tk.TRUE)

root.mainloop()

清除按钮也有效，但之后开始按钮不再有效。 如果有人也可以帮助我。

您可以将当前的clear()函数替换为：

def clear():
    t.clear()

如果您只想擦除已绘制的路径但将乌龟留在它结束的位置。 如果要擦除路径并将海龟重置回起点，请执行以下操作：

def clear():
    t.reset()