如何在根TopLevel下的Python Tkinter框架中布局窗口小部件

Question

Here is the code:

class Window(Frame):
    def __init__(self, master = None):
        Frame.__init__(self, master)
        self.master = master
        self.init_window()
    def init_window(self):
        self.master.title('GUI')

        row = 0
        self.s_date_label = Label(self, text = 'Start Date: ')
        self.s_date_label.grid(row=row, column=0, sticky = W)
        self.start_date = Entry(self, bd=1)
        self.start_date.grid(row=row, column=1, sticky = W)
        self.s_date_label2 = Label(self, text = 'example: 20160101')
        self.s_date_label2.grid(row=row, column=2, sticky = W)

        self.datetype_var = IntVar()
        R1 = Radiobutton(root, text="20160101", variable=self.datetype_var, value=8)
        R1.grid(row=row, column=1, sticky = W)
        R1.select()
        R2 = Radiobutton(root, text="201601", variable=self.datetype_var, value=6)
        R2.grid(row=row, column=2, sticky = W)
        R3 = Radiobutton(root, text="2016", variable=self.datetype_var, value=4)
        R3.grid(row=row, column=3, sticky = W)

root = Tk()
root.geometry('600x400')

app = Window(root)

root.mainloop()

Here is the output:

My Label and Entry both do not show up.

I have found that Radiobutton do not have self. and Label and Entry have it.

However, I don't know why this will cause the result.

Answer 1

Update

I had suggested 2 approaches to solve this. First one is to use the root Tk object as the parent for all the widgets; Second is to add the widgets to Window , and add Window object to the layout manager of the root . As Bryan Oakley mentioned (correctly) in the comments, the first approach is not as good (although it works, but still). So I'm suggesting to use the second approach (discussed below), which is:

Make sure all the widgets ( Radiobutton , Label , Entry , etc.) are using the Window object (referenced by self ) as the parent, and then add the window instance to the layout manager of the root . Either in init_window call, or after creating the object.

Approach 1

The widgets under the Window , should use self as the parent (to preserve hierarchy), and the Window itself, should be added to layout manager of master . This way all the widgets will show correctly

You should have passed the Tk object (referenced by root ) when adding the widgets to the layout (in this case the grid geometry).

from Tkinter import *

class Window(Frame):
    def __init__(self, master = None):
        Frame.__init__(self, master)
        self.master = master
        self.init_window()

    def init_window(self):
        self.master.title('GUI')

        row = 0
        self.s_date_label = Label(self.master, text = 'Start Date: ')
        self.s_date_label.grid(row=row, column=0, sticky = W)
        self.start_date = Entry(self.master, bd=1)
        self.start_date.grid(row=row, column=1, sticky = W)
        self.s_date_label2 = Label(self.master, text = 'example: 20160101')
        self.s_date_label2.grid(row=row, column=2, sticky = W)

        self.datetype_var = IntVar()
        R1 = Radiobutton(self.master, text="20160101", variable=self.datetype_var, value=8)
        R1.grid(row=row, column=1, sticky = W)
        R1.select()
        R2 = Radiobutton(self.master, text="201601", variable=self.datetype_var, value=6)
        R2.grid(row=row, column=2, sticky = W)
        R3 = Radiobutton(self.master, text="2016", variable=self.datetype_var, value=4)
        R3.grid(row=row, column=3, sticky = W)

root = Tk()
root.geometry('600x400')

app = Window(root)

root.mainloop()

Note that the parent (first argument passed to Label and Entry constructors), are changed from self to self.master .

Also the parent for Radiobutton are also changed from root to self.master , because then root is a reference to the global variable, and not the actual parent set for Window object.

Update (description)

The code on the question is adding the Label and Entry widgets to self (the Window object), so when calling grid on them it's using the grid layout of the window object . But the window object itself, was not added to the root (Tk) , so basically the window object and it's attached widgets would not show at all.

The Radiobutton instances however, were attached to root , so calling grid on them would add them to layout manager of the root (Tk) , that's why they were showing.

One fix for this, is to keep using root as the parent for all widgets, which causes the window object to be like a data container, but not a widget on the UI.

Approach 2

Add the window object itself to the layout manager of the root . Something like this:

#all the code is the same as the question
# ...
app = Window(root)
app.grid(row=0, column=0, sticky=NW)
# the rest of the code

But remember that if you'd like to use this approach (using the window object as a Widget container as well), then again I'd suggest that all the Radiobutton to use self (the window object) as their parents instead of root . Because when using root as the parent, calling grid(row=0, column=0) on radio buttons, they would be using the same row/column that the window object (frame) is using.

Answer 2

app is an instance of Window . Window is a Frame . The widgets created by init_window sometimes have self as the parent, and sometimes root . The first thing you need to fix is that they all need to have a parent of self . The point of this sort of design, which you've no doubt copied from somewhere, is that everything inside this class should be contained in this frame.

Because app is an instance of Window and Window is a subclass of Frame , everything that goes in this widget will be invisible unless app is visible. So, the second part of the solution is to make app visible. You can do this however you want. In this particular case, since it's the only widget in the root window, I would use pack:

app = Window(root)
app.pack(fill="both", expand=True)

Answer 3

You're making the label and entry their own parents and not starting their own event loops. Instead of self , try changing their parent to root .