如何在选择 tkinter 按钮后从使用 filedialog 打开文件的函数返回变量?

Question

我看过的所有教程都只使用链接到tkinter按钮的函数中收集的信息来定义tkinter filedialog.askopenfilename函数。我可以在函数中传递信息，但我想在函数外部传递变量(文件路径、图像等)，并让它们在我的 GUI 中更新变量。 我已经注释掉了我想在下面的函数中调用变量的位置main_gui_setup。任何帮助将不胜感激，因为无法打开文件非常令人沮丧。如果这个问题仍然存在，我作为程序员的未来可能仅限于为 Youtube 创建井字游戏或教学视频。

from tkinter import *
import tkinter as tk
from tkinter import ttk
from tkinter import filedialog, messagebox
from PIL import ImageTk, Image # was import PIL.Image, PIL.ImageTk
import cv2

def main():
root = Tk()
window1 = Window(root, "X-ray Assist", "Give up")
return None

# can't pass by reference in python
class Window():
n = 0
file_path = ""
img1_info = ""
def __init__(self, root, title, message):
self.root = root
self.root.title(title)
#self.root.geometry(geometry)
self.screen_width = root.winfo_screenwidth()
self.screen_height = root.winfo_screenheight()
#self.root.attributes('-topmost', 1)
# SET APP WINDOW SIZE
scr_size_main = self.scr_size() # create instance of scr_size
self.root.geometry("%dx%d+%d+%d" % (self.root_width, self.root_height, self.root_x, self.root_y))
# CREATE MAIN WINDOW GUI
create_gui = self.main_gui_setup()
self.root.mainloop()

pass
def scr_size(self):
'''Reads monitor size and adjusts GUI frame sizes'''        
self.root_width = int(self.screen_width*0.52)
self.root_height = int(self.screen_height*0.9)
self.root_x = int(self.screen_width*0.23)
self.root_y = int(self.screen_height*0.02)        
self.img_ht_full = int(self.screen_height*0.82)   
self.tools_nb_width = int(self.screen_width*0.22)
self.tools_nb_height = int(self.screen_height*0.48)     
self.hist_nb_width = int(self.screen_width*0.22)
self.hist_nb_height = int(self.screen_height*0.23)
def open_image(self):

main_win = ttk.Frame(self.root)
main_win.grid(column=0, row=0)  

self.file_path = filedialog.askopenfilename(initialdir='/', title='Open File', 
filetypes=(('tif files', '*.tif'), ('all files', '*.*')))
self.file_path_label = ttk.Label(main_win, text=self.file_path)
self.file_path_label.grid(column=0, row=0, columnspan=1, sticky="nw", padx=(5,0), pady=1)    
self.img1_8bit = cv2.imread(self.file_path, 0) #, cv2.IMREAD_ANYDEPTH | cv2.IMREAD_GRAYSCALE)
#self.img1_8bit_resize = cv2.resize(self.img1_8bit, (self.img_ht_full, self.img_ht_full)) #, interpolation = cv2.INTER_CUBIC)
#self.img1_height, self.img1_width = self.img1_8bit.shape # not resized for screen
#img1_info = text = f"{self.img1_height} {self.img1_8bit.dtype} {self.img1_16bit.dtype}"
#print(self.img1_width, " x ", self.img1_height, " bitdepth = ", self.img1_8bit.dtype)

#img1_info = ttk.Label
#print(f"{self.img1_height} {self.img1_width} {self.img1_8bit.dtype}")
#img1_info.grid(column=3, row=1, columnspan=1, sticky="w", padx=(5,0), pady=1)

#img = io.imread(main_win.filename) #scikit

self.img1_16bit = cv2.imread(self.file_path, cv2.IMREAD_ANYDEPTH | cv2.IMREAD_GRAYSCALE)
#self.img_canvas = tk.Canvas(self.root, width=self.img_ht_full, height=self.img_ht_full)
#self.img_canvas.grid(column=1, row=2, columnspan=10, rowspan=10, sticky="nw")
#self.img_canvas.image = ImageTk.PhotoImage(image=Image.fromarray(self.img1_8bit_resize))
#self.img_canvas.create_image(0,0, image=self.img_canvas.image, anchor="nw")

# .create_line(x1, y1, x2, y2, fill="color")
#self.img_canvas.create_line((self.img_ht_full/2), 0, (self.img_ht_full/2), (self.img_ht_full), fill="yellow")
#self.img_canvas.create_line(0, (self.img_ht_full/2), (self.img_ht_full), (self.img_ht_full/2), fill="yellow")

def main_gui_setup(self):
main_win = ttk.Frame(self.root)
main_win.grid(column=0, row=0)
image_win = ttk.Frame(main_win, borderwidth=25, relief="groove", width=self.img_ht_full, height=self.img_ht_full)                 
image_win.grid(column=1, row=2, columnspan=10, rowspan=10, sticky="nw")
toolbar = ttk.Frame(main_win, borderwidth=5) #, width=1100, height=15)
toolbar.grid(column=0, row=0, columnspan=10, rowspan=1, sticky="nw", padx=20)
hist_win = ttk.Frame(main_win, borderwidth=25, relief="groove", width=300, height=200)
panel_info = ttk.Label(main_win, text=f"{self.screen_width} x {self.screen_height}")
panel_info.grid(column=5, row=1, columnspan=1, sticky="e", pady=1)
# SCROLL SLIDER AT BOTTOM
slider = ttk.Scrollbar(main_win, orient="horizontal")
slider.grid(column=1, row=13, columnspan=7, padx=5, pady=5, sticky="ew")
#X-RAY AND DETECTOR SETTINGS - will input these from separate class
kv = ttk.Label(main_win, text="125kV") 
kv.grid(column=0, row=2, columnspan=1, padx=15, pady=5)
file_path_label = ttk.Label(main_win, text="No image loaded")
file_path_label.grid(column=1, row=1, columnspan=1, sticky="nw", padx=(5,0), pady=1)  

# CREATE BUTTONS
open = ttk.Button(toolbar, text="Open", width=10, command=self.open_image)
open.grid(column=0, row=0)
save = ttk.Button(toolbar, text="Save", width=10)
save.grid(column=1, row=0)
b1 = ttk.Button(toolbar, text="1", width=10)
b1.grid(column=2, row=0)
b2 = ttk.Button(toolbar, text="2", width=10)
b2.grid(column=3, row=0)
pass
main()

Answer 1

您没有正确考虑事件驱动编程。在事件驱动编程中，您有对定义的函数的回调。让我们看一下您的代码：

def get_path(self):
...
self.path_label = ...
...

def main_gui_setup(self):
main_win = ttk.Frame(self.root)
main_win.pack()
open = ttk.Button(main_win, text="Open", width=10, command=self.get_path)
open.pack()
# Problematic code:
# main_label = ttk.Label(main_win, self.path_label)
# main_label.pack()

调用main_gui_setup时，它会在其中创建一个框架和一个按钮。单击按钮时，它会调用设置path_label变量的get_path。您面临的问题是，一旦您创建按钮(无需等待按下按钮)，您就会创建名为main_label.

要简单解决问题，请尝试以下操作：

def get_path(self):
...
self.file_path = ...
self.path_label = ...
...
def button_callback(self, main_win):
# set up
self.get_path()
# My guess is that you wanted `self.file_path` here instead of `self.path_label`
main_label = ttk.Label(main_win, self.file_path)
main_label.pack()
def main_gui_setup(self):
main_win = ttk.Frame(self.root)
main_win.pack()
# I am using a lambda and passing in `main_win` because you haven't
# assigned it to `self` using `self.main_win = ...`
open = ttk.Button(main_win, text="Open", width=10, command=lambda: self.button_callback(main_win))
open.pack()

Answer 2

我仍然对您要完成的任务感到困惑：

from tkinter import Tk, Button, Label, filedialog

class MainWindow(Tk):
def __init__(self):
Tk.__init__(self)
self.open_file_btn = Button(self, text='Open', command=self.open_file)
self.open_file_btn.pack()

self.file_name = None
def open_file(self):
self.file_name = filedialog.askopenfilename()
Label(self, text=self.file_name).pack()

root = MainWindow()
root.mainloop()

我将解释这里会发生什么！(您可以明显更改.askopenfilename()属性)。

当程序打开文件对话框并选择文件时，该文件名现在将分配给self.file_name并且该变量可以在类中的任何位置使用。

也从我所看到的你应该了解更多关于课程和 PEP 8 的信息