How to save image data from clipboard to a file in Python 3 on Debian, using tkinter?

Question

I'm trying to use the tkinter solution for obtaining clipboard image data copied from GIMP, but cannot make it work, saving the data to file:

from tkinter import Tk
r = Tk()
r.withdraw()
clip = r.clipboard_get(type="image/png")
r.update()
r.destroy()
with open("testbytes.png", mode="bw+") as f:
    f.write(clip.encode())

When I try to open the testbytes.png file, the Image Viewer reports a fatal error, not a PNG file. I obtained the type parameter for the clipboard_get() call with r.selection_get(selection='CLIPBOARD', type='TARGETS'), which returned:

'TIMESTAMP TARGETS MULTIPLE SAVE_TARGETS image/png image/bmp image/x-bmp image/x-MS-bmp image/x-icon image/x-ico image/x-win-bitmap image/vnd.microsoft.icon application/ico image/ico image/icon text/ico image/tiff image/jpeg '

I think the format of the data on the clipboard is PNG. I've also tried JPEG, BMP and TIFF, but they result in similar errors.

What am I doing wrong?

Have you looked in the file to see what it looks like, or used some other tool that can attempt to detect the file type? Also, why are you calling `encode` on the data? — Bryan Oakley, Jan 24 '19 at 16:19
@BryanOakley During the various tests that I was doing, Python reported the type of data on the clipboard being `str`. I use `encode` to get `bytes`. The data looks like this - `b'0x89 0x50 0x4e 0x47 0xd 0xa 0x1a 0xa 0x0 0x0 0x0 0xd 0x49...`. I don't know what other tool to use to get file type. — Theo d'Or, Jan 24 '19 at 16:40
I have now run the `file testbytes.png` command in Terminal and get this response: `testbytes.png: ASCII text, with very long lines, with no line terminators`. Not what it should be, is it? — Theo d'Or, Jan 24 '19 at 16:55
`b'0x89 0x50 0x4e ...` isn't PNG data, it's a hex dump of PNG data. — jasonharper, Jan 24 '19 at 17:37
@jasonharper Thanks for that! Running `xxd -r -p testbytes.hex > testbytes.png` to convert the hex dump to binary, produces a file that in Image Viewer results in the "PNG file corrupted by ASCII conversion" error. This error results both when I save the original string read from the clipboard, as well as when encoding to bytes. Doing some searches on the topic of hexdump-to-binary conversion, it appears such conversions are not always straightforward. I need to find out what's wrong with the hexdump and a method of converting correctly. — Theo d'Or, Jan 24 '19 at 19:07

score 0 · Answer 1 · answered Jan 25 '19 at 13:45

Using a conversion method, obtained in a separate SO question, for the hexdump of PNG data that tkinter provides from the clipboard, the correct code is:

from tkinter import Tk
r = Tk()
r.withdraw()
clip = r.clipboard_get(type="image/png")
r.update()
r.destroy()
# Convert hexdump to bytes
clip = bytes([eval(h) for h in clip.strip().split(' ')])
with open("testbytes.png", mode="bw+") as f:
    f.write(clip)

Apart from writing out a PNG file, the data may also be loaded with the pillow module (formerly known as PIL):

import io
from PIL import Image
cf = io.BytesIO(clip)
cim = Image.open(cf)
cim.show()

As far as I've been able to determine, this is the best method of reading a PNG file from the clipboard into Python 3 on Linux (Debian).

score 0 · Answer 2 · answered May 27 '20 at 12:35

I have created a tool for this intended for windows. The code could be used for debian as well. This script monitors for change in your clipboard and pops up a tkinter window asking you the filename to be used for saving the image, if it is not present in the folder. The image is then saved into the folder as a PNG file. It is particularly helpful with the windows shortcut Windows + Shift + S used to snip the screen.

Please find it here: https://github.com/Mitzzzzz/Clipboard-Image-Saver

How to save image data from clipboard to a file in Python 3 on Debian, using tkinter?

2 Answers2