Question

我在这里没有几行代码可以在tkinter canvas中绘制圆圈，但是我想做的就是将草图停在开始的位置，所以我要睡觉，但是我要在草图停到的位置停下来然后继续。

所以我写了这个函数

def stop_extent():

    canvas.create_arc(0, 0, 0, 0, extent=0, outline="red", tags=("arc",))
    extent = float(canvas.itemcget("arc", "extent"))
    extent = extent + 5.0
    canvas.itemconfigure("arc", extent=extent)
    canvas.after(100, stop_extent)

并将所有值设置为0，但仍然不会停止它，标签也没有配置。

import tkinter as tk
import time



def change_extent():
    l.config(text="sketch in progress...")

    canvas.create_arc(350, 100, 220, 220, extent=0, outline="yellow", tags=("arc",))
    extent = float(canvas.itemcget("arc", "extent"))
    extent = extent + 5.0
    canvas.itemconfigure("arc", extent=extent)
    canvas.after(100, change_extent)



def stop_extent():
    l.config(text="sketch stopped...")
    time.sleep(10)
    l.config(text="sketch stopped...")


root = tk.Tk()
root.geometry("600x400")

canvas = tk.Canvas(root, width=200, height=200, background="dodger blue")
canvas.pack(fill="both", expand=True)


l = tk.Label(canvas, bg="dodger blue",  fg="white")
l.place(x=250, y=20)


b= tk.Button(canvas, text="Start sketch", command=change_extent, width=25, fg='dodger blue')
b.place(x=220, y=330)


b= tk.Button(canvas, text="stop sketch", command=stop_extent, width=25, fg='dodger blue')
b.place(x=220, y=370)


root.mainloop()

Answer 1

您可以在canvas.after方法中跟踪change_extent产生的回叫，并在canvas.after_cancel方法中使用stop_extent取消回叫；在下面的示例中，我使用全局变量stop进行演示。

在GUI应用程序中使用time.sleep通常是一个坏主意。

每次修改圆弧的范围时，您也不需要重新创建圆弧，但这超出了问题的范围。

import tkinter as tk
import time


def change_extent():
    global stop
    l.config(text="sketch in progress...")
    extent = float(canvas.itemcget(arc_item, "extent"))
    canvas.itemconfigure("arc", extent=extent+5)
    stop = canvas.after(100, change_extent)


def stop_extent():
    l.config(text="sketch stopped...")
    print(stop)
    canvas.after_cancel(stop)
    canvas.itemconfigure("arc", extent=0)   # <- reset to straight line start



stop = None
root = tk.Tk()
root.geometry("600x400")

canvas = tk.Canvas(root, width=200, height=200, background="dodger blue")
canvas.pack(fill="both", expand=True)

arc_item = canvas.create_arc(350, 100, 220, 220, extent=0, outline="yellow", tags=("arc",))


l = tk.Label(canvas, bg="dodger blue",  fg="white")
l.place(x=250, y=20)


b= tk.Button(canvas, text="Start sketch", command=change_extent, width=25, fg='dodger blue')
b.place(x=220, y=330)


b= tk.Button(canvas, text="stop sketch", command=stop_extent, width=25, fg='dodger blue')
b.place(x=220, y=370)


root.mainloop()

如何在tkinter画布中停止素描

1 个答案: