Treeview - 在忽略长函数之前调用设置列文本

Treeview - call to set column text before long function ignored

我是使用 tkinter 和 python 进行 GUI 编程的新手 3.

它应该做什么:

我的应用程序从医学期刊文章中提取 DOI。 PDF 使用 ttk.Treeview 显示。双击文件会启动文本提取功能,最多可能需要 5 秒,具体取决于 PDF 的大小。调用函数前状态栏显示 "processing ...",调用后显示 "complete"。

这是我可怜的进度条版本,因为我还没有学过那些或线程。

实际发生了什么:

双击文件启动功能,然后将状态列设置为"complete"。它从不显示 "processing".

我在这里错过了什么?

示例

这将创建一个 ttk.Treeview 并加载当前目录。双击任意文件都要设置状态,等待4秒(模拟冗长功能),再设置状态。

import os, time
import tkinter as tk
from tkinter import ttk

class DirBrowser(tk.Frame):

    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent
        self.path = os.getcwd()
        self.setup_tree()


    def setup_tree(self):
        self.tree = ttk.Treeview(self, columns=('status'))
        self.tree.pack(expand=True, fill=tk.BOTH)

        self.tree.heading("#0", text="Directory", anchor='w')
        self.tree.heading('status', text='Status', anchor='w')

        self.tree.bind('<Double-Button-1>', self.on_dblclick)

        for directory, subdir_list, file_list in os.walk(self.path):
            node = self.tree.insert('', 'end', text=directory)

            for file in file_list: 
                self.tree.insert(node, 'end', text=file)


    def on_dblclick(self, event):
        selected = self.tree.selection()[0]

        # set status column to 'processing'
        self.tree.set(selected, 'status', 'processing ...')

        # simulate a time-consuming function
        # the real program extracts text from a PDF here
        time.sleep(4)

        # set status column to 'complete'
        self.tree.set(selected, 'status', 'complete')


if __name__ == '__main__':
    master = tk.Tk()
    tree = DirBrowser(master).pack(fill=tk.BOTH, expand=True)
    master.mainloop()

更改TreeView文本后需要更新界面如下

    def on_dblclick(self, event):
            selected = self.tree.selection()[0]

            # set status column to 'processing'
            self.tree.set(selected, 'status', 'processing ...')

            # Update (like a single step of mainloop)
            self.parent.update()  # <-- ADD

            # simulate a time-consuming function
            # the real program extracts text from a PDF here
            time.sleep(4)

            # set status column to 'complete'
            self.tree.set(selected, 'status', 'complete')