有没有办法从tkinter.PhotoImage实例获取tkinter.Label对象？我知道有this question，它有一个部分令人满意的答案，但我真的需要得到一个PhotoImage对象：
>>> import tkinter as tk
>>>
>>> root = tk.Tk()
>>>
>>> image1 = tk.PhotoImage(file="img.gif")
>>> image2 = tk.PhotoImage(file="img.gif")
>>>
>>> label = tk.Label(root, image=image1)
>>> label._image_ref = image1
>>> label.cget("image") == image2
False
是否有一个允许我从pyimage字符串中获取图像对象的函数？即一个从label.cget("image")获得？
答案是apparantly，你做不到。你可以得到的最接近的是获取图像源（文件或数据）并检查（可能是通过散列）这两个图像是否相同。 tkinter.PhotoImage 不实现__eq__，因此您无法仅比较两个图像以获得相同的数据。这是一个解决问题的最后一个例子（主要是）：
import hashlib
import os
import tkinter as tk
_BUFFER_SIZE = 65536
def _read_buffered(filename):
"""Read bytes from a file, in chunks.
Arguments:
- filename: str: The name of the file to read from.
Returns:
- bytes: The file's contents.
"""
contents = []
with open(filename, "rb") as fd:
while True:
chunk = fd.read(_BUFFER_SIZE)
if not chunk:
break
contents.append(chunk)
return bytes().join(contents)
def displays_image(image_file, widget):
"""Check whether or not 'widget' displays 'image_file'.
Reading an entire image from a file is computationally expensive!
Note that this function will always return False if 'widget' is not mapped.
This doesn't work for images that were initialized from bytes.
Arguments:
- image_file: str: The path to an image file.
- widget: tk.Widget: A tkinter widget capable of displaying images.
Returns:
- bool: True if the image is being displayed, else False.
"""
expected_hash = hashlib.sha256(_read_buffered(image_file)).hexdigest()
if widget.winfo_ismapped():
widget_file = widget.winfo_toplevel().call(
widget.cget("image"), "cget", "-file"
)
if os.path.getsize(widget_file) != os.path.getsize(image_file):
# Size differs, the contents can never be the same.
return False
image_hash = hashlib.sha256(
_read_buffered(widget_file)
).hexdigest()
if image_hash == expected_hash:
return True
return False