使用tkinter编辑文本时显示下拉列表组合框 [英] Show combobox drop down while editing text using tkinter

问题描述

打开下拉菜单时是否可以使Combobox可编辑?我还没有找到任何解决方案.我想使其更像Google搜索，但使用ComboBox.

Is it possible to make Combobox editable while dropdown is opened? I haven't found any solution. I want to make it more like Google Search but using ComboBox.

推荐答案

问题:在编辑文本时显示 Combobox PopdownWindow

Question: Show Combobox PopdownWindow, while editing text

此示例将 ttk.Combobox 扩展到以下内容:

This example extends a ttk.Combobox to the following:

• 键入时显示PopdownWindow
• 在按键'< Down>'
上打开PopdownWindow
• 如果在 Listbox
中的第一项上，则在按下键的'< Up'上关闭PopdownWindow

• Show the PopdownWindow while typing
• Open the PopdownWindow on Key-pressed '<Down>'
• Close the PopdownWindow on Key-pressed '<Up', if at the first item in the Listbox

参考:

• 事件和绑定

对于每个小部件，您都可以将Python函数和方法绑定到事件.

For each widget, you can bind Python functions and methods to events.

ttk :: combobox —带有弹出式选择列表的文本字段

ttk::combobox — text field with popdown selection list

ttk :: combobox 在内部使用 entry 和 listbox 小部件.

1. 继承自 ttk.Combox

import tkinter as tk
import tkinter.ttk as ttk


class Combobox(ttk.Combobox):

Helper函数，用于将内部 Toplevel 和 Listbox 映射到 tkinter 对象.

警告:这使用了 Tk/Tcl 内部，如有更改，恕不另行通知.
这可能仅适用于经过测试的Tk/Tcl版本！

WARNING: This uses Tk/Tcl internals, which could change without notice.
This may working only with the tested Tk/Tcl version!

def _tk(self, cls, parent):
    obj = cls(parent)
    obj.destroy()
    if cls is tk.Toplevel:
        obj._w = self.tk.call('ttk::combobox::PopdownWindow', self)
    else:
        obj._w = '{}.{}'.format(parent._w, 'f.l')
    return obj

初始化对象，获取内部引用并绑定到按键事件

Initalize the object, get the internal references and bind to Key-press events

def __init__(self, parent, **kwargs):
    super().__init__(parent, **kwargs)
    self.popdown = self._tk(tk.Toplevel, parent)
    self.listbox = self._tk(tk.Listbox, self.popdown)

    self.bind("<KeyPress>", self.on_keypress, '+')
    self.listbox.bind("<Up>", self.on_keypress)

按键处理程序，以显示或隐藏PopdownWindow并设置键盘焦点.

Key-pressed handler to show or hide the PopdownWindow and set the Keyboard focus.

def on_keypress(self, event):
    if event.widget == self:
        state = self.popdown.state()

        if state == 'withdrawn' \
                and event.keysym not in ['BackSpace', 'Up']:
            self.event_generate('<Button-1>')
            self.after(0, self.focus_set)

        if event.keysym == 'Down':
            self.after(0, self.listbox.focus_set)

    else:  # self.listbox
        curselection = self.listbox.curselection()

        if event.keysym == 'Up' and curselection[0] == 0:
            self.popdown.withdraw()

用法:

class App(tk.Tk):
    def __init__(self):
        super().__init__()

        values = ('one', 'two', 'three', 'four', 'five', 'six', 'seven')

        self.cb = Combobox(self, value=values)
        self.cb.grid(row=0, column=0)


if __name__ == "__main__":
    App().mainloop()

使用Python测试:3.5-'TclVersion':8.6'TkVersion':8.6

Tested with Python: 3.5 - 'TclVersion': 8.6 'TkVersion': 8.6

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