我無法系結箭頭鍵事件

我目前有一個下一個切片和上一個切片按鈕，可以單擊以在影像中移動。我還希望鍵盤的左右箭頭允許用戶瀏覽上一個和下一個切片。所以應該有兩種方法來瀏覽影像。我無法在prev_image和 中讓鍵盤點擊作業next_image。

import tkinter as tk

class App(tk.Frame):
    def __init__(self, master=None):
        super().__init__(master)  # python3 style
    
        self.master.title("Slideshow")

        top_frame = tk.Frame(self)
        top_frame.pack()
    
        image_frame = tk.Frame(self)
        image_frame.pack()

        previous_button = tk.Button(top_frame, text="Previous Slice", command=self.prev_image)
        previous_button.pack(side="left")

        next_button = tk.Button(top_frame, text="  Next Slice  ", command=self.next_image)
        next_button.pack(side="left")

        self.canvas = tk.Canvas(image_frame, bg='red')
        self.canvas.pack()
    
        self.canvas.bind('<Left>', self.prev_image)
        self.canvas.bind('<Right>', self.next_image)
        self.canvas.focus_set()

        self.master.bind('<Left>', self.prev_image)
        self.master.bind('<Right>', self.next_image)
    
    def prev_image(self, event=None):
        print('prev_image')
        if event:
            print('even:', event)

    def next_image(self, event=None):
        print('next_image')
        if event:
            print('even:', event)

root = tk.Tk()
app = App(root)
app.pack()
root.mainloop()

 

圖片：

uj5u.com熱心網友回復：

你必須設定focus上canvas得到的鑰匙canvas

        self.canvas.bind('<Left>', self.prev_image)
        self.canvas.bind('<Right>', self.next_image)
        self.canvas.focus_set()

或者您可以將鍵系結到主視窗

        self.master.bind('<Left>', self.prev_image)
        self.master.bind('<Right>', self.next_image)

第二個版本可能會更好，因為canvas可能會丟失focus- 即。當您使用鍵tab從小部件跳轉到小部件時。

其他問題。

command=需要不獲取引數但bind()需要獲取一個引數的函式 - 因為它發送有關事件的資訊（即按下的鍵、滑鼠位置等）

要在其中使用相同的函式command=，bind()您需要具有默認值的引數 - 即。even=None

    def prev_image(self, event=None):
        # ... code ...

    def next_image(self, event=None):
        # ... code ...

最小作業示例：

import tkinter as tk

class App(tk.Frame):
    def __init__(self, master=None):
        super().__init__(master)  # python3 style
        
        self.master.title("Slideshow")

        top_frame = tk.Frame(self)
        top_frame.pack()
        
        image_frame = tk.Frame(self)
        image_frame.pack()
    
        previous_button = tk.Button(top_frame, text="Previous Slice", command=self.prev_image)
        previous_button.pack(side="left")

        next_button = tk.Button(top_frame, text="  Next Slice  ", command=self.next_image)
        next_button.pack(side="left")

        self.canvas = tk.Canvas(image_frame, bg='red')
        self.canvas.pack()
        
        #self.canvas.bind('<Left>', self.prev_image)
        #self.canvas.bind('<Right>', self.next_image)
        #self.canvas.focus_set()

        self.master.bind('<Left>', self.prev_image)
        self.master.bind('<Right>', self.next_image)
        
    def prev_image(self, event=None):
        print('prev_image')
        self.canvas['bg'] = 'blue'
        if event:
            print('even:', event)

    def next_image(self, event=None):
        print('next_image')
        self.canvas['bg'] = 'green'
        if event:
            print('even:', event)


if __name__ == "__main__":
    app = App()
    app.pack()
    app.mainloop()
    
    #root = tk.Tk()
    #app = App(root)
    #app.pack()
    #root.mainloop()

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