如何实现GUI按钮选择图片文件后在新窗口中显示？

Got it, let's get your code working properly—right now it's just launching a file picker but not actually displaying the selected image in a new window. Let's walk through the fixes and the complete working version:

First, let's spot the issues in your original code: #

• You created two Tk instances (window = tk.Tk() and a = Tk())—this causes weird Tkinter behavior, we only need one main window.
• The openimgfile function only selects a file but doesn't load or display the image.
• Using filedialog.askopenfile() returns a file object, but we need the file path to load the image with PIL, so askopenfilename() is better here.
• When you do button1 = Button(...).pack(), button1 ends up as None (since pack() returns nothing)—it's cleaner to separate widget creation and layout.

Here's the corrected, working code: #

import tkinter as tk
from tkinter import filedialog
from PIL import Image, ImageTk
import os

# Only one main window—no duplicates!
root = tk.Tk()
root.title("Pattern Matching")
root.minsize(200, 200)

def open_and_display_image():
    # Get current working directory as starting point
    currdir = os.getcwd()
    # Ask user to select an image file, get the file path
    file_path = filedialog.askopenfilename(
        initialdir=currdir,
        title="Select an Image",
        filetypes=(
            ("PNG Files", "*.png"),
            ("JPEG Files", "*.jpg;*.jpeg"),
            ("All Files", "*.*")
        )
    )
    
    # If user cancels the dialog, do nothing
    if not file_path:
        return
    
    # Load the image with PIL
    try:
        image = Image.open(file_path)
        # Optional: Resize image if it's too big (adjust max size as needed)
        max_dimension = 800
        width, height = image.size
        if width > max_dimension or height > max_dimension:
            ratio = min(max_dimension/width, max_dimension/height)
            image = image.resize((int(width*ratio), int(height*ratio)), Image.Resampling.LANCZOS)
        
        # Create a new top-level window to display the image
        img_window = tk.Toplevel(root)
        img_window.title("Image Preview")
        
        # Convert PIL image to Tkinter-compatible format
        tk_image = ImageTk.PhotoImage(image)
        
        # Create a label to hold the image and pack it
        img_label = tk.Label(img_window, image=tk_image)
        img_label.image = tk_image  # Keep a reference to avoid garbage collection
        img_label.pack(padx=10, pady=10)
        
    except Exception as e:
        # Show error if image can't be loaded
        error_window = tk.Toplevel(root)
        error_window.title("Error")
        tk.Label(error_window, text=f"Could not load image:\n{str(e)}").pack(padx=20, pady=20)

# Create button and layout separately
open_button = tk.Button(root, text="Open File", width=10, height=2, command=open_and_display_image)
open_button.pack(pady=50)

root.mainloop()

Key improvements explained: #

• Single main window: We use root = tk.Tk() as the only main application window to prevent Tkinter conflicts.
• Image loading & display: The open_and_display_image function now:
  • Gets the file path with askopenfilename()
  • Uses PIL to load and optionally resize the image (so huge images don't break the window)
  • Creates a new Toplevel window to show the image
  • Converts the PIL image to ImageTk.PhotoImage and keeps a reference to it (critical—otherwise Tkinter garbage collects the image and it won't show up)
• Error handling: Added a try/except block to catch issues like invalid image files, so the app doesn't crash silently.
• Cleaner button setup: Separated button creation and pack() so we can reference the button later if needed.

内容的提问来源于stack exchange，提问作者user11185769