python tkinter 列表框事件绑定

2022-01-16 00:00:00 python tkinter widget listbox

问题描述

我无法让事件绑定与 python/tkinter 一起使用.我只是尝试单击并打印位置，但每次执行此操作时，结果都是-1".

I'm having trouble getting an event binding to work with python/tkinter. I'm simply trying to click and have the location printed, but every time I do this, "-1" is the result.

这是我的代码

from Tkinter import *
import Tkinter

class make_list(Tkinter.Listbox):

    def __init__(self,master, **kw):
        frame = Frame(master)
        frame.pack()
        self.build_main_window(frame)

        kw['selectmode'] = Tkinter.SINGLE
        Tkinter.Listbox.__init__(self, master, kw)
        master.bind('<Button-1>', self.click_button)
        master.curIndex = None

    #display the clicked location
    def click_button(self, event):
        self.curIndex = self.nearest(event.x)
        print self.curIndex

    #display the window, calls the listbox
    def build_main_window(self, frame):
        self.build_listbox(frame)

    #listbox
    def build_listbox(self, frame):
        listbox = Listbox(frame)
        for item in ["one", "two", "three", "four"]:
            listbox.insert(END, item)    
        listbox.insert(END, "a list entry")
        listbox.pack()
        return

if __name__ == '__main__':
    tk = Tkinter.Tk()
    make_list(tk)
    tk.mainloop()

更新的代码 - 我摆脱了框架，但我似乎无法弄清楚为什么函数 click_button 中的第一个打印语句得到 -1

from Tkinter import *
import Tkinter

class make_list(Tkinter.Listbox):

    #display the clicked location
    def click_button(self, event):
        ##this block works
        w = event.widget
        index = int(w.curselection()[0])
        value = w.get(index)
        print value
        ##this doesn't
        self.curIndex = self.nearest(event.y)
        print self.curIndex
        self.curIndex = event.widget.nearest(event.y)
        print self.curIndex

    #display the window, calls the listbox
    def build_main_window(self):
        self.build_listbox()

    #listbox
    def build_listbox(self):
        listbox = Listbox()
        listbox.bind('<<ListboxSelect>>', self.click_button)
        for item in ["one", "two", "three", "four"]:
            listbox.insert(END, item)    
        listbox.insert(END, "a list entry")
        listbox.pack()
        return

if __name__ == '__main__':
    tk = Tkinter.Tk()
    start = make_list(tk)
    start.build_main_window()
    start.mainloop()

解决方案

listbox 最近的项目是由 y 找到的，而不是 x.

listbox nearest item is found by y, not x.

 self.nearest(event.x)     # wrong
 self.nearest(event.y)     # right

更新:我首先没有注意到真正的问题:

Update: I didn't notice the real problem first:

    listbox = Listbox(frame)

它不是你子类化的同一个列表框，它是另一个不相关的列表框.你的列表框(是 make_list)是空的，这就是为什么它总是返回-1表示最近的.

It's not the same listbox which you subclassed, it's another unrelated listbox. Your listbox (which is make_list) is empty, that's why it always returns -1 for nearest.

也许子类化一个框架是一个好主意(无论如何，比子类化列表框并在其中添加一个带有另一个列表框的框架更好).然后你必须在那个不为空的 real 列表框上绑定事件.

Perhaps subclassing a frame is a good idea (anyway, better than subclassing listbox and adding a frame with another listbox into it). Then you'll have to bind event on that real listbox which is not empty.

查看它将修复后如何工作的快速方法是使用 event.widget 调用真实列表框的 nearest:

Quick way to see how it will work when fixed is to call nearest of a real listbox with event.widget:

self.curIndex = event.widget.nearest(event.y)

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