python - MVC tkinter 模型。在框架之间切换，添加新框架

Question

我正在关注MVC model Brian 在“在 tkinter 中的两个框架之间切换”的答案中做出的回答。他将这些框架堆叠在一起(所有这些都是一开始就制作的)，然后我们就按照自己的意愿展示它们。

程序开始运行后是否可以添加另一个框架，或者只有使用此模型才能查看开始时创建的框架？ (感谢给出的答案，我能够弄清楚如何做到这一点)

但是第二页仍然存在问题，因为它不是 100% 独立的。每次调用框架时，它都不会从 strach 开始。

以下是我对代码所做的修改。

import tkinter as tk                # python 3
from tkinter import font  as tkfont # python 3
#import Tkinter as tk     # python 2
#import tkFont as tkfont  # python 2

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")

        # the container is where we'll stack a bunch of frames
        # on top of each other, then the one we want visible
        # will be raised above the others
        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 = {}
        for F in (StartPage, PageOne):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame

            # put all of the pages in the same location;
            # the one on the top of the stacking order
            # will be the one that is visible.
            frame.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()

    def add_PageTwo (self):

        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["PageTwo"] = PageTwo(parent=container, controller=self)
        self.frames["PageTwo"].grid(row=0, column=0, sticky="nsew")        

        self.show_frame("PageTwo")


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)

        button2 = tk.Button(self, text="Go to Page One",
                        command=lambda: controller.show_frame("PageOne"))
        button2.pack()

class PageOne(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is page 1", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)
        button1 = tk.Button(self, text="Go to the page 2",
                           command=lambda: controller.add_PageTwo())
        button1.pack()
        button2 = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        button2.pack()        

class PageTwo(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is page 2. GREAT", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)
        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        button.pack()


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

Answer 1

错误在于 PageNew 类定义:

class PageNew(tk.Frame, parent, controller):
    ...

括号中的名称是 PageNew 将继承的类，而您可能打算将它们作为 __init__ 方法的参数传递。

在脚本的这一点上，parent 将引用名为 parent 的模块级变量。但是，这样的变量不存在，导致 NameError。

您需要删除这些，并仅保留tk.Frame。

class PageNew(tk.Frame):
    ...

至于你的问题，是的，可以在运行时创建框架，然后显示它们。它们不需要在初始化时全部创建。