ttk.Combobox 当状态为只读且失焦时出现故障 [英] ttk.Combobox glitch when state is read-only and out of focus

问题描述

当 ttk.Combobox 为只读且未处于焦点时，其文本背景变为白色，与灰色字段背景不同，并使组合框看起来很丑:

When a ttk.Combobox is read-only and not in focus, its text background gets white which differs from the gray field background and makes the combobox look ugly:

所需的样式将是第二个样式.如何让组合框像这样工作?

The desired style would be the second one's. How to make a combobox work like that?

推荐答案

解决方案是将 ttk 样式改成这样:

The solution is to change the ttk style like this:

s = ttk.Style()
s.map("TCombobox",
    selectbackground=[
        ('!readonly', '!focus', 'SystemWindow'),
        ('readonly', '!focus', 'SystemButtonFace'),
        ],
    )

这会全局更改组合框的行为.在下面的演示中(问题的屏幕截图来自该演示)，我为工作良好的组合框定义了一个自定义样式为Alt.TCombobox"，并使用了它:

This changes the behavior of the comboboxes globally. In the following demo (from which the screenshot of the question was made) I defined a custom style for the nicely working combobox as "Alt.TCombobox" and used that one for it:

# cboxdemo.py by Adam Szieberth (2013)
# Python 3.3.0

"""Read-only Ttk.Combobox style demo module.

The style of the second combobox has been slightly modified to
make text background match with combobox background when out of
focus.

In read-only state (which is default) you can notice that text
background gets white in the first (original styled) combobox
when focus moves towards. Second combobox looks nice then.

With the button you can test that the two works exactly the same
in writeable state.
"""

from random import randint
from tkinter import Button, Frame, StringVar, Tk
from tkinter.ttk import Combobox, Style

class App(Frame):
    def __init__(self, parent):
        super().__init__(parent)
        self.state = None
        self.style = Style()
        self.style.map("Alt.TCombobox",
            selectbackground=[
                ('!readonly', '!focus', 'SystemWindow'),
                ('readonly', '!focus', 'SystemButtonFace'),
                ],
            )
        self.button = Button(self, text="Change state!",
            command=self.switch)
        self.cbox1var, self.cbox2var = StringVar(), StringVar()
        self.cbox1 = Combobox(self,
            exportselection=0,
            values=["sex", "sleep", "eat", "drink", "dream",],
            textvariable=self.cbox1var,
            )
        self.cbox1.bind('<<ComboboxSelected>>', self.bfocus)
        self.cbox1.current(1)
        self.cbox2 = Combobox(self,
            exportselection=0,
            values=["fear", "clarity", "power", "old age",],
            style="Alt.TCombobox",
            textvariable=self.cbox2var,
            )
        self.cbox2.bind('<<ComboboxSelected>>', self.bfocus)
        self.cbox2.current(3)
        self.cbox1.pack()
        self.cbox2.pack()
        self.button.pack()
        self.switch()

    def bfocus(self, *args):
        if randint(0,1):
            self.button.focus()
            print('Focus moved!')
        else:
            print('Focus stayed.')

    def switch(self):
        if self.state == ['readonly']:
            self.state = ['!readonly']
            print('State is writeable!')
        else:
            self.state = ['readonly']
            print('State is read-only!')
        self.cbox1.state(self.state)
        self.cbox2.state(self.state)

if __name__ == "__main__":
    root = Tk()
    root.title('ttk.Combobox styling')
    App(root).pack()
    root.mainloop()

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