如何引用Python类__init__方法中创建的tkinter元素并更新界面内容

核心问题梳理 #

• PageOne类__init__方法中创建的scroll_area、canvas等界面元素都是局部变量，未绑定到类实例，导致update_results方法无法访问这些元素。
• 调用update_results的方式错误，直接调用类方法而非已实例化的页面对象的方法，运行时无法匹配实例属性。
• 滚动区域未绑定尺寸变化事件，新增内容后滚动条无法适配内容高度，无法滚动查看超出范围的内容。
• 重复触发生成逻辑时，旧结果不会被清空，会和新内容叠加显示。

修正后完整代码 #

import tkinter as tk
from tkinter import font as tkfont


class SampleApp(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")

        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}

        self.frames["StartPage"] = StartPage(parent=container, controller=self)
        self.frames["PageOne"] = PageOne(parent=container, controller=self)

        self.frames["StartPage"].grid(row=0, column=0, sticky="nsew")
        self.frames["PageOne"].grid(row=0, column=0, sticky="nsew")

        self.show_frame("StartPage")

    def show_frame(self, page_name):
        '''Show a frame for the given page name'''
        frame = self.frames[page_name]
        frame.tkraise()


class StartPage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is the start page", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)

        button1 = tk.Button(self, text="Go to Page One",
                            command=lambda: controller.show_frame("PageOne"))

        button1.pack()


class stored_functions():
    # 调整参数顺序，第一个参数接收传入的PageOne实例
    def get_date(self, page_instance, entry):
        results = []
        for x in range(1,21):
            answer = int(entry.strip()) * x
            results.append([x, answer])
        # 用实例调用方法，而非直接调用类方法
        page_instance.update_results(results)


class PageOne(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        title = tk.Label(self, text='Enter a Number')
        title.pack()
        self.text = tk.Text(self, font=controller.title_font, width=8, height=1)
        self.text.pack()
        button = tk.Button(self, text="Get Multiplication Table",
                           command=lambda: stored_functions().get_date(self, entry=self.text.get('1.0', tk.END)))
        button.pack()

        divider = tk.Label(self, text='-------------------------------------------------')
        divider.pack()

        scrollable_frame = tk.Frame(self)
        scrollable_frame.config(width=50, height=100)
        scrollable_frame.pack()
        # 绑定到实例属性，供其他方法访问
        self.canvas = tk.Canvas(scrollable_frame)
        self.scroll_area = tk.Frame(self.canvas)
        scroll_bar = tk.Scrollbar(scrollable_frame, orient='vertical', command=self.canvas.yview)
        self.canvas.config(width=250, height=100, yscrollcommand=scroll_bar.set)
        self.canvas.pack(side="left", fill="both", expand=True)
        self.canvas.create_window((4,4), window=self.scroll_area, anchor='nw')
        # 绑定内容尺寸变化事件，自动更新滚动范围
        self.scroll_area.bind("<Configure>", lambda e: self.canvas.configure(scrollregion=self.canvas.bbox("all")))

        header = tk.Label(self.scroll_area, text='Multiplication Table')
        header.grid(row=0, column=0, padx=(10, 10), pady=10)

    def update_results(self, results):
        # 先清空滚动区域旧内容
        for widget in self.scroll_area.winfo_children():
            widget.destroy()
        # 重新加表头
        header = tk.Label(self.scroll_area, text='Multiplication Table')
        header.grid(row=0, column=0, padx=(10, 10), pady=10)
        entry = results[0][1]
        row=2
        for i in results:
            statement = '{} multiplied by {} is {}.'.format(entry, i[0], i[1])
            statement_text = tk.Text(self.scroll_area, height=1)
            statement_text.grid(row=row, column=0)
            statement_text.configure(state='normal')
            statement_text.insert(tk.END, statement)
            statement_text.configure(state='disabled')
            row += 1


if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

内容的提问来源于stack exchange，提问作者Lzypenguin