Tkinter游戏关卡：切换新图片后计时器加速问题求助

问题原因 #

每次切换国旗时，旧的计时器任务（通过new.after()创建的定时回调）没有被取消，导致多个计时任务同时在后台运行，叠加后就会出现倒计时速度越来越快的现象。

解决方案 #

通过跟踪计时器任务ID，在启动新计时前取消旧任务，确保同一时间只有一个计时器在运行。

修改后的完整代码 #

def medium_level():
    global score2, current_image2, total_games, total_w
    total_games += 1
    current_image2 = 0
    score2 = 0
    timer_id = None  # 新增：存储当前计时器任务ID
    new = Toplevel(window)
    new.title("Medium Mode")
    new.configure(background=bg2)
    new.geometry("600x500")
    
    ans = tk.Entry(new, font=('Times', 25))
    ans["justify"] = "center"
    ans["borderwidth"] = "1px"
    ans.place(x=90, y=270, width=414, height=188)

    rules2 = tk.Label(new, font=('Times', 20), bg=bg2)
    rules2["text"] = "Enter Country Name Here:"
    rules2["justify"] = "center"
    rules2.place(x=110, y=230)

    timelbl = tk.Label(new, text="Time: ", font=('Times', 15), bg=bg2)
    timelbl.place(x=480, y=50)
    
    score_label = tk.Label(new, text="Score: 0"+"/12", font=('Times', 15), bg=bg2)
    score_label.place(x=40, y=50)

    image_label = tk.Label(master=new)
    image_label.place(relx=0.30, rely=0.10)
    
    image_files = ['bangladesh.png', 'germany.png', 'turkey.png', 'egypt.png', 'madagascar.png','ecuador.png','croatia.png','palestine.png','south africa.png','mongolia.png','peru.png','vietnam.png']
    random.shuffle(image_files)
    
    def next_image2():
        global current_image2, countdown
        if current_image2 < len(image_files):
            image_path = image_files[current_image2]
            image = tk.PhotoImage(file=image_path)
            image_label.configure(image=image)
            image_label.image = image

            current_image2 += 1
            start_timer()  # 直接调用start_timer，它会重置countdown并取消旧任务
            timelbl.config(text=f"Time: {countdown}")
            
        else:
            messagebox.showinfo("Game Over", f"Your score is: {score2}"+"/12")
            new.quit()

    def start_timer():
        nonlocal timer_id  # 访问外层函数的timer_id变量
        global countdown
        # 取消之前未完成的计时器任务
        if timer_id is not None:
            new.after_cancel(timer_id)
        countdown = 20
        update_timer()

    def update_timer():
        nonlocal timer_id
        global countdown
        timelbl.config(text=f"Time: {countdown}")

        if countdown == 0:
            next_image2()
        else:
            countdown -= 1
            # 保存新的计时器任务ID，方便后续取消
            timer_id = new.after(1000, update_timer)
    
    def check_answer2(event):
        global score2, total_w, countdown
        user_answer = ans.get().strip().lower()
        correct_answer = image_files[current_image2 - 1].split('.')[0].lower()

        if user_answer == correct_answer:
            score2 += 1
            total_w += 1
            score_label.config(text=f"Score: {score2}"+"/12")

        ans.delete(0, tk.END)
        next_image2()

    ans.bind('<Return>', check_answer2)
    next_image2()

关键改动说明 #

• 新增timer_id变量：用于记录当前正在运行的计时器任务ID，确保能定位并取消旧任务。
• start_timer函数优化：每次启动新计时前，调用new.after_cancel(timer_id)终止之前的计时任务，避免多任务叠加。
• update_timer函数优化：将new.after()返回的任务ID存入timer_id，为下次取消任务提供依据。

内容的提问来源于stack exchange，提问作者jjk