Python GUI 之 Combobox 学习

1. 序言

    本章介绍tkinter.ttk的Combobox控件。

2. 环境信息

    ********************************
    本系列运行平台：Windows10 64bit
    Python 版本：3.7

   ********************************   

3. Combobox

    Combobox为下拉列表控件，它可以包含一个或多个文本项(text item)，可以设置为单选或多选。使用方式为ttk.Combobox(root,option...)。

常用的参数列表如下：

参数	描述
master	代表了父窗口
height	设置显示高度、如果未设置此项，其大小以适应内容标签
width	设置显示宽度，如果未设置此项，其大小以适应内容标签
state	可读状态，如state= “readonly”
textvariable	设置textvariable属性

一些常用的函数：

函数	描述
get	返回制定索引的项值，如listbox.get(1)；返回多个项值,返回元组，如listbox.get(0,2)；返回当前选中项的索引listbox.curselection()
values	设定下拉列表的内容。如 data = ["a","b","c"], cbx["values"] = data
current(i)	指定下拉列表生成时显示在列表值，i = index。如current(2)，显示列表中的第三个值

事件：

下拉列表没有command函数（方法)。

下拉列表的虚拟事件是 "<<ComboboxSelected>>"。

 

4. 实例

实例1

from tkinter import *
from tkinter import ttk

#Create an instance
win = Tk()
win.title("Learn Combobox")

#create a Label
lb1 = Label(win, text = "Below is a combobox 1", font = "tahoma 12 normal")
lb1.grid(column = 0, row = 0, padx = 8, pady = 4)

def show_select_1():
	print("post_command: show_select")
	print(value.get())

#Define tkinter data type
data = ["a","b","c"]
value = StringVar()

#Create a combobox, and tighter it to value
cbx_1 = ttk.Combobox(win, width = 12, height = 8, textvariable = value, postcommand = show_select_1)
cbx_1.grid(column = 0, row = 1)

#add data to combobox
cbx_1["values"] = data

#======================================================================================================
#create a Label
lb2 = Label(win, text = "Below is a combobox 2", font = "tahoma 12 normal")
lb2.grid(column = 0, row = 4, padx = 8, pady = 4)

def show_data_2(*args):
	print("Event: ComboboxSelected")
	print(cbx_2.get())

#Define tkinter data type
data2 = ["a2","b2","c2","d2","e2"]

#Create a combobox, and tighter it to value
cbx_2 = ttk.Combobox(win, width = 12, height = 8)
cbx_2.grid(column = 0, row = 5)

#set cbx_2 as readonly
cbx_2.configure(state = "readonly")

#add data to combobox
cbx_2["values"] = data2
#set the initial data [index =2] to shows up when win generated
cbx_2.current(2)

#bind a event
cbx_2.bind("<<ComboboxSelected>>", show_data_2)

win.mainloop()