如何让图片适配Tkinter全屏窗口？代码异常求助

问题描述 #

尝试让图片适配自定义的Tkinter全屏窗口边界，运行代码后图片仅约四分之一区域占满整个屏幕，与预期全屏适配效果不符，控制台无任何警告或报错。

原代码 #

import sys
import random
import tkinter as tk
from tkinter import *
from PIL import Image, ImageTk

window = tk.Tk()
width = window.winfo_screenwidth()
height = window.winfo_screenheight()
window.geometry("%dx%d" % (width, height))
window.title("War of the Ring")

def CloseProgram():
    window.destroy()
    window.quit()

def PlayMainGame():
    #Destroy widgets and title
    Title.destroy()
    NewGameButton.destroy()
    LoadGameButton.destroy()
    OptionsButton.destroy()
    global ResizedBoardImage
    canvas = Canvas(window, width = width, height = height)
    canvas.pack()
    BoardImage = Image.open("Middle Earth Map.jpg")
    ResizedBoardImage = BoardImage.resize((width, height), )
    ResizedBoardImage = ImageTk.PhotoImage(BoardImage)
    canvas.create_image(10,10, anchor = NW, image = ResizedBoardImage)

问题原因 #

代码存在两个关键问题：

1. 逻辑错误：调用BoardImage.resize()生成了适配窗口尺寸的新图片，但随后将ResizedBoardImage重新赋值为原图片的PhotoImage，完全没用到缩放后的新图片。
2. 坐标偏差：canvas.create_image用了(10,10)作为起始点，导致图片和窗口边缘有10像素间隙，不符合全屏需求。

另外resize方法未指定重采样滤镜，可能导致图片缩放质量不佳。

修正后的代码 #

import sys
import random
import tkinter as tk
from tkinter import *
from PIL import Image, ImageTk

window = tk.Tk()
width = window.winfo_screenwidth()
height = window.winfo_screenheight()
window.geometry("%dx%d" % (width, height))
window.title("War of the Ring")

def CloseProgram():
    window.destroy()
    window.quit()

def PlayMainGame():
    # 销毁原有组件
    Title.destroy()
    NewGameButton.destroy()
    LoadGameButton.destroy()
    OptionsButton.destroy()
    global ResizedBoardImage
    canvas = Canvas(window, width=width, height=height)
    canvas.pack()
    BoardImage = Image.open("Middle Earth Map.jpg")
    # 缩放图片到窗口尺寸，指定高质量重采样滤镜
    ResizedBoardImage = BoardImage.resize((width, height), Image.Resampling.LANCZOS)
    # 基于缩放后的图片生成PhotoImage
    ResizedBoardImage = ImageTk.PhotoImage(ResizedBoardImage)
    # 从窗口左上角(0,0)开始绘制图片
    canvas.create_image(0, 0, anchor=NW, image=ResizedBoardImage)

额外优化（可选） #

如果需要保持图片宽高比避免拉伸变形，可以计算适配窗口的最佳尺寸并居中显示：

def get_scaled_size(img_width, img_height, win_width, win_height):
    scale = min(win_width / img_width, win_height / img_height)
    return int(img_width * scale), int(img_height * scale)

# 在PlayMainGame函数中替换resize相关代码
img_width, img_height = BoardImage.size
scaled_width, scaled_height = get_scaled_size(img_width, img_height, width, height)
ResizedBoardImage = BoardImage.resize((scaled_width, scaled_height), Image.Resampling.LANCZOS)
# 居中显示图片
canvas.create_image((width - scaled_width)//2, (height - scaled_height)//2, anchor=NW, image=ResizedBoardImage)

注：如果使用旧版本PIL库，将Image.Resampling.LANCZOS替换为Image.LANCZOS即可。

内容的提问来源于stack exchange，提问作者JesseF3