Tkinter：提高框架时的焦点问题

Question

以下代码是触摸屏的GUI（没有鼠标，没有键盘）。输入是触摸屏，它的响应类似于鼠标点击。这是从一个更大的程序中剥离出来以显示问题。它有3个框架根据需要提出。理想情况下，我希望焦点无处可去直到用户点击（指向）一个字段，然后键盘输入数字在框架 Machine 1 或 Machine 2 的聚焦区域中。效果很好，但如果用户没有在输入字段中首先 "click"，则会生成异常：AttributeError: 'machine1' 对象没有属性 'insert'.

如果键盘输入为 "bit bucket" 或一个不可见（且未使用）的虚拟输入字段，但可以接受默认情况下，当一个框架被抬起时，焦点会自动放在第一个字段。

经过数小时的网络研究，我一直无法找到解决方案。感谢您为我指明正确的方向。

import tkinter as tk
from tkinter import font  as tkfont  

class MyApp(tk.Tk):

    def __init__(self, *args, **kwargs):

        tk.Tk.__init__(self, *args, **kwargs)

        self.title_font = tkfont.Font(family='Helvetica', size=18, weight="bold", slant="italic")

        # the container is where we stack the frames
        # then the one we want visible is raised above the others
        container = tk.Frame(self)
        container.grid(row=0, column=0, sticky='news')
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}
        self.frames["machine1"] = machine1(parent=container, controller=self)
        self.frames["machine2"] = machine2(parent=container, controller=self)
        self.frames["running"] = running(parent=container, controller=self)


        self.frames["machine1"].grid(row=0, column=0, sticky="nsew")
        self.frames["machine2"].grid(row=0, column=0, sticky="nsew")
        self.frames["running"].grid(row=0, column=0, sticky="nsew")

        self.show_frame("running")

    def show_frame(self, page_name):
        '''Show a frame for the given page name'''
        frame = self.frames[page_name]
        frame.tkraise()
        frame.focus_set() # this removed focus from the hidden window



class Keypad(tk.Frame):

    cells = [
        ['1', '2', '3', '4', '5'],
        ['6', '7', '8', '9', '0'],
        ]

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        for y, row in enumerate(self.cells):
            for x, item in enumerate(row):
                b = tk.Button(self, text=item, command=lambda text=item:self.append(text))
                b.grid(row=y, column=x, sticky='news')

        x = tk.Button(self, text='Backspace', command=self.backspace)
        x.grid(row=0, column=10, sticky='news')

        x = tk.Button(self, text='Clear', command=self.clear)
        x.grid(row=1, column=10, sticky='news')


    def get(self):
        widget = self.focus_get()
        return widget.get()

    def append(self, text):
    # get the widget with the focus
         widget = self.focus_get()
    # insert the value
         widget.insert("insert", text)

    def clear(self):
        widget = self.focus_get()
        widget.delete(0, 'end')

    def backspace(self):
        widget = self.focus_get()
        text = widget.get()
        text = text[:-1]
        self.clear()
        self.append(text)


class machine1(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="Machine 1", font=controller.title_font)
        label.grid(row=0, column=0, sticky='news')

        e1 = tk.Entry(self, highlightthickness = 2)
        e1.grid(row=2, column=0, sticky='news')
        e1.focus_set()   # by default start with this one

        e2 = tk.Entry(self, highlightthickness = 2)
        e2.grid(row=3, column=0, sticky='news')

        kbd = Keypad(self)
        kbd.grid(row=5, column=0, columnspan=3)

        button3 = tk.Button(self, text="Run",
                            command=lambda: controller.show_frame("running"))
        button3.grid(row=6, column=2, sticky='news')        


class machine2(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="Machine 2", font=controller.title_font)
        label.grid(row=0, column=0, sticky='news')

        e1 = tk.Entry(self, highlightthickness = 2)
        e1.grid(row=2, column=0, sticky='news')
        e1.focus_set()   # by default start with this one

        e2 = tk.Entry(self, highlightthickness = 2)
        e2.grid(row=3, column=0, sticky='news')

        kbd = Keypad(self)
        kbd.grid(row=5, column=0, columnspan=3)

        button3 = tk.Button(self, text="Run",
                            command=lambda: controller.show_frame("running"))

        button3.grid(row=6, column=2, sticky='news')


class running(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="Run", font=controller.title_font)
        label.grid(row=0, column=0, sticky='news')

        button1 = tk.Button(self, text="Machine 1",
                           command=lambda: controller.show_frame("machine1"))
        button2 = tk.Button(self, text="Machine 2",
                           command=lambda: controller.show_frame("machine2"))

        button1.grid(row=5, column=0, sticky='news')
        button2.grid(row=5, column=1, sticky='news')

        e1 = tk.Entry(self, highlightthickness = 2)
        e1.grid(row=1, column=1, sticky='news')


if __name__ == "__main__":

    app = MyApp()
    app.geometry("800x480")
    app.mainloop()
``b

Answer 1

有些东西总是有焦点，即使它只是根 window。

对于您的情况，最简单的解决方案是验证焦点是否位于条目小部件上，您可以这样做：

def append(self, text):
     widget = self.focus_get()
     if widget.winfo_class() == "Entry":
         widget.insert("insert", text)

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