错误Fram上的Tkinter小部件

Question

我试图使用像素来调整输入框的大小，所以我必须创建一个帧来获得正确的大小。我还使用一个类来创建tkinter输入框，以便我可以将占位符放入框中。这两者是分开工作的；然而，当放在一起时，输入框拒绝进入正确的框架，即使我已经指定了框架

import Tkinter as tk
from Tkinter import *

class GUI:

    def __init__(self, root):
        self.usernameFrame = Frame(root, height=50, width=300, bg="GREEN", bd=3)
        self.usernameFrame.pack_propagate(0)
        self.usernameFrame.pack()

        self.usernameEntry = EntryPlaceholder(self.usernameFrame, "Username")
        self.usernameEntry.pack()


class EntryPlaceholder(Entry, object):

    def __init__(self, master=None, placeholder="placeholder"):
       super(EntryPlaceholder, self).__init__()

       self.placeholder = placeholder

       self.bind("<FocusIn>", self.clearText)
       self.bind("<FocusOut>", self.insertText)

       self.insertText()

    def insertText(self, *args):
        if self.get() == "":
            self.insert(0, self.placeholder)

    def clearText(self, *args):
        if self.get() == self.placeholder:
            self.delete(0, END)

root = tk.Tk()
gui = GUI(root)
root.mainloop()

小部件只是放在根框架上

Answer 1

考虑此代码：

def __init__(self, master=None, placeholder="placeholder"):
   super(EntryPlaceholder, self).__init__()

您没有将master传递给EntryPlaceHolder的__init__，因此它被放在根窗口中

代码必须是这样的：

def __init__(self, master=None, placeholder="placeholder"):
   super(EntryPlaceholder, self).__init__(master)