python tkinter listbox事件绑定

问题描述

我在获取事件绑定以使用python/tkinter时遇到麻烦.我只是想单击并打印位置，但是每次这样做，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()

更新后的代码-我摆脱了框架，但似乎无法弄清楚为什么我在click_button函数中的第一个打印语句中得到-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()

推荐答案

listbox由y而不是x查找到最近的项目.

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)

它不是您子类化的列表框，而是另一个不相关的列表框. 您的列表框(是 make_list)为空，这就是为什么它总是返回-1为最接近的原因.

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.

也许对框架进行子类化是个好主意(无论如何，比对列表框进行子类化并向其中添加具有另一个列表框的框架更好).然后，您必须在不为空的 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.

查看修正后的工作方式的快速方法是使用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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