python - 如何使用回调来更改多个 tkinter 检查按钮
问题描述
我有多个 tk.Checkbuttons 在单击（或更改）时应该共享相同的回调。复选框的变量（状态）应该在状态更改时触发的回调中可用（并用于所有检查按钮）。有很多这样的文章，其中大多数处理状态变量的并行列表。因为我想避免单独的变量列表，因为 checkboxex 的数量会因数据变化而变化，所以我在两个版本中创建了自己的 Checkbutton 类，但是两个版本都有缺点，所以这就是我需要一些建议的地方。
这两个类都包含一个状态变量的实例来保存状态（避免管理单独的状态变量列表）并在单击时触发一个动作。所以我的问题与回调有关。
第一类显示在这个最小化的运行示例中：
#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
# in action(command) procedure
# Parameters:
# userdata: User defined, for example index of a database table row related to the CB
# action : command to execute when clicked. Replaces command variable because
# command does not provide the event information when called. Event
# information is needed to get the checkbox data within action.
class myCheckButton(tk.Checkbutton):
def __init__(self, parent, userdata, action, *args, **kwargs):
# state holds the state of the CB (False = unchecked, True = checked)
self.state = BooleanVar(value=False)
# add the state variable to tk.Ckeckbutton args
kwargs['variable'] = self.state
# init tk.Checkbutton
super().__init__(parent, *args, **kwargs)
# bind action to myCheckButton using <Button-1> (left mouse button)
self.bind('<Button-1>', action)
# store userdata for usage in the action procedure
self.userdata = userdata
#-------------------------------------------------------------------------------
def onCbClicked(event):
# get the calling widget containing all data we need to know
sender = event.widget
# get the status of CB. "not" because action runs before status change
status = not sender.state.get()
# do something by using text, status and/or user defined variable
if status == True:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
else:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", userdata=1, action=onCbClicked)
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", userdata=2, action=onCbClicked)
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to true
mycb2.state.set(True)
root.mainloop()
这里的缺点是回调仅在单击时调用，而不是在我调用 .state.set(bool) 更改状态时调用（参见倒数第二行）。有没有办法（除了我使用跟踪的第二个解决方案）来解决这个问题？优点是我可以使用传递给它的事件在回调中清楚地识别调用实例。
第二种解决方案类似，优点是当状态变量发生变化时也会调用回调，而无需单击小部件。缺点是我必须通过将跟踪变量命名为与实例相同的名称来传递 Checkbutton 的实例名称以在回调中识别它。另外，我不确定这种识别调用实例的方式是否保存。
我的第二个解决方案的最小化示例：
#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
# in action(command) procedure
# Parameters:
# instName: Name of the CB instance to use in onCbChange
# userdata: User defined, for example index of a database table row related to the CB
# action : command to execute when status changes.
class myCheckButton(tk.Checkbutton):
def __init__(self, parent, instName, userdata, action, *args, **kwargs):
# state holds the state of the CB (False = unchecked, True = checked)
# the name of the internal variable is set to the instance name of this class.
self.state = BooleanVar(value=False, name=instName)
# Trace the state variable to call action procedure when it changes.
self.state.trace("w", action)
# add the state variable to tk.Ckeckbutton args
kwargs['variable'] = self.state
# init tk.Checkbutton
super().__init__(parent, *args, **kwargs)
# store userdata for usage in the action procedure
self.userdata = userdata
#-------------------------------------------------------------------------------
def onCbChange(*args):
# get the calling widget containing all data we need to know from *args.
# This requires the name of the traced variable is the same as name of the widget instance.
sender = eval(args[0])
# get the status of CB.
status = sender.state.get()
# do something by using text, status and/or user defined variable
if status == True:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
else:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", instName="mycb1", userdata=1, action=onCbChange)
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", instName="mycb2", userdata=2, action=onCbChange)
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to true
mycb2.state.set(True)
root.mainloop()
即使这是我的首选解决方案：是否可以通过 eval 传递给跟踪回调的第一个参数来确定调用实例（假设正确的名称被传递给构造函数）？有没有更好的方法来识别来电者？例如，通过以某种方式传递事件以能够识别类似于第一个解决方案的调用者？
提前感谢您的帮助。
编辑：
按照 acw1668 的提示，我将 myCheckButton 类从第一个解决方案更改为：
class myCheckButton(tk.Checkbutton):
def __init__(self, parent, userdata, action, *args, **kwargs):
# state holds the state of the CB (False = unchecked, True = checked)
self.state = BooleanVar(value=False)
# add the state variable to tk.Ckeckbutton args
kwargs['variable'] = self.state
# init tk.Checkbutton
super().__init__(parent, *args, **kwargs)
# bind action to myCheckButton using <Button-1> (left mouse button)
self.bind('<Button-1>', action)
# store userdata for usage in the action procedure
self.userdata = userdata
# store action
self.action = action
# add widget property
self.widget = self
def set(self, status):
# only when status changes:
if status != self.state.get():
# callback before status change
self.action(self)
# change status
self.state.set(status)
我不确定从 set 过程将“事件”传递给回调的方法是否是最好的，但它在调用 .set(bool) 时有效。
最终解决方案
这是自定义检查按钮的完整最终解决方案。感谢 Matiiss 和 acw1668：
#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
# in action(command) procedure
# Parameters:
# userdata: User defined, for example index of a database table row related to the CB
class myCheckButton(tk.Checkbutton):
def __init__(self, parent, userdata, *args, **kwargs):
# state holds the state of the CB (False = unchecked, True = checked)
self.state = BooleanVar(value=False)
# add the state variable to tk.Ckeckbutton args
kwargs['variable'] = self.state
# init tk.Checkbutton
super().__init__(parent, *args, **kwargs)
# store userdata for usage in the action procedure
self.userdata = userdata
def set(self, status):
# only when status changes:
if status != self.state.get():
if status == True: self.deselect()
else: self.select()
self.invoke()
#-------------------------------------------------------------------------------
def onCbClicked(sender):
# get the status of CB.
status = sender.state.get()
# do something by using text, status and/or user defined variable
if status == True:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
else:
print("CB(" + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", userdata=1, command=lambda: onCbClicked(mycb1))
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", userdata=2, command=lambda: onCbClicked(mycb2))
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to test status change callback
mycb2.set(True)
root.mainloop()
解决方案
我仍然有点困惑，但这就是你想要的：
from tkinter import Tk, Checkbutton
root = Tk()
c = Checkbutton(root, text='Apple')
c.pack()
c.bind('<Button-1>', lambda e: print(e.widget))
root.mainloop()
使用这样的函数来模拟用户与复选框的交互（选中用于选择，取消选中用于取消选择）
def check():
c.deselect()
c.invoke()
def uncheck():
c.select()
c.invoke()
你只需要找到一种方法来调用这些函数
完整的代码示例：
from tkinter import Tk, Checkbutton, Button, IntVar
def toggle(widget):
state = var.get()
if state == 0:
print('off')
if state == 1:
print('on')
print(widget)
def check():
c.deselect()
c.invoke()
def uncheck():
c.select()
c.invoke()
root = Tk()
var = IntVar()
c = Checkbutton(root, text='Apple', variable=var, command=lambda: toggle(c))
c.pack()
Button(root, text='On', command=check).pack()
Button(root, text='Off', command=uncheck).pack()
root.mainloop()
请注意，使用按钮会触发复选框命令，而仅使用.select/.deselect不会这样做
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