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TKinter:捕获按键时无响应

keypress tkinter python

anthony · 技术社区 · 9 年前

我可能对捕捉按键的工作原理有一个根本的误解。我已经设置了基本的按键和效果,但当我尝试在更大的脚本中执行相同的操作时,它没有效果。例如,第一个程序工作得很好。我按下空格键,窗口关闭。

import Tkinter as tk
class ExampleApp(tk.Tk):
    def __init__(self):
        def pressSpace(event):
            self.destroy()

        tk.Tk.__init__(self)
        w, h = self.winfo_screenwidth(), self.winfo_screenheight()
        self.geometry("%dx%d+0+0" % (w, h))
        self.bind("<space>", pressSpace)
if __name__ == "__main__":
    app = ExampleApp()
    app.mainloop()

但当按下空格时,第二个按钮似乎没有任何作用。

#Program has been greatly simplified without affecting the outcome
import Tkinter as tk
class ExampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)

        # make program fullscreen
        w, h = self.winfo_screenwidth(), self.winfo_screenheight()
        self.geometry("%dx%d+0+0" % (w, h))

        self.label = tk.Label(self)
        self.label.pack()
        self.remaining = 0
        self.countdown(15)

    def countdown(self, remaining = None):
        paused = 0
        def pressSpace(event):
            if(paused == 0):
                paused = 1
            else:
                paused = 0

        #bind spacebar to pause the timer
        self.bind(self, "<space>", pressSpace)

        if remaining is not None:
            self.remaining = remaining

        if self.remaining <= 0:
            #Time has expired. Players lose
            self.label.configure(text="TIME!", fg='black', bg='brown')
        else:
            #There is still time on the clock. This cuts the time into readable chunks
            self.label.configure(text= str(self.remaining) + ' - Paused = ' + str(paused))
            if(paused == 0):
                #Check if the timer is toggled to pause
                self.remaining = self.remaining - 1
                self.after(1000, self.countdown)
if __name__ == "__main__":
    app = ExampleApp()
    app.mainloop()

我不明白。程序在功能上似乎相似,所有内容都包含在同一个函数中,但变量“暂停”似乎根本没有改变,计时器也不会停止。

我很害怕。我是否偏离了正道?

1 回复 | 直到 9 年前

Anand S Kumar 9 年前

代码中存在大量问题-

你的装订似乎不对-
```
self.bind(self, "<space>", pressSpace)
```
不确定为什么要发送 self 再一次你应该这样做-
```
self.bind("<space>", pressSpace)
```
在您的功能中- pressSpace() -因为你正在设置 paused=0 或 paused=1 ,paused被视为该函数的局部变量,因此您将得到一个错误- UnboundLocalError: local variable 'paused' referenced before assignment 。相反,我会让你设置 paused 作为上的实例变量 自己 并使用它。
其次,即使绑定变得正确,在每次调用 countdown ,你正在改变 暂停 返回到 0 。为此,您应该将绑定和设置暂停为0逻辑移动到 __init__() 。然后,当应用程序未打开时,您需要重新开始倒计时。

有效的代码-

import Tkinter as tk
class ExampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)

        # make program fullscreen
        w, h = self.winfo_screenwidth(), self.winfo_screenheight()
        self.geometry("%dx%d+0+0" % (w, h))

        self.label = tk.Label(self)
        self.label.pack()
        self.remaining = 0
        self.paused = 0
        def pressSpace(event):
            if(self.paused == 0):
                self.paused = 1
            else:
                self.paused = 0
                self.countdown()

        #bind spacebar to pause the timer
        self.bind("<space>", pressSpace)
        self.countdown(15)

    def countdown(self, remaining = None):
        if remaining is not None:
            self.remaining = remaining

        if self.remaining <= 0:
            #Time has expired. Players lose
            self.label.configure(text="TIME!", fg='black', bg='brown')
        else:
            #There is still time on the clock. This cuts the time into readable chunks
            self.label.configure(text= str(self.remaining) + ' - Paused = ' + str(self.paused))
            if(self.paused == 0):
                #Check if the timer is toggled to pause
                self.remaining = self.remaining - 1
                self.after(1000, self.countdown)
if __name__ == "__main__":
    app = ExampleApp()
    app.mainloop()