XDGViewer and GmDisplayViewer fail to show images

[alv2017]

What did you do?

1. I created script to check Unix image viewers available in PIL.ImageShow module. The script example for XDGViewer is provided
   below.

2. I run the script for all Linux/Unix viewers except XVViewer (I didn't manage to obtain it)

What did you expect to happen?

I expected to open my image with each single viewer I tried to use:
XDGViewer, DisplayViewer, GmDisplayViewer, EogViewer

What actually happened?

The image failed to open with

a) XDGViewer
b) GmDisplayViewer

What are your OS, Python and Pillow versions?

• OS: Ubuntu, 20.04.3 LTS (Focal Fossa)
• Python: 3.9.9
• Pillow: 9.1.0.dev0

from PIL import Image
from PIL.ImageShow import XDGViewer

if __name__ == "__main__":
    viewer = XDGViewer()
    img_file = "path/to/image_file"
    with Image.open(img_file) as im:
        viewer.show(im)

[radarhere]

When you use GmDisplayViewer, what error do you see?

[alv2017]

In case of GmDisplayViewer the image is not showing up, without reporting anything.
I suspect that the image gets closed before the user sees it.

[radarhere]

If you modify your Pillow installation to include sleep 20 before removing the image file - radarhere@3eae2ef - does that fix both XDGViewer and GmDisplayViewer?

[alv2017]

I think that I might have a better solution. :)
(adding sleep 20 fixes the problem)

[alv2017]

I also suggest to have a look at Open multiple images case. This doesn't work as expected as well: try sliding through the images in a viewer.

import os
from PIL import Image


if __name__ == "__main__":
    img_dir = "path/to/img/directory"
    img_files = ["file1.png", "file2.png", "file3.png"]

    for img_file in img_files:
        img_location = os.path.join(img_dir, img_file)
        with Image.open(img_location) as im:
            im.show(im)

[radarhere]

Just for the record - im.show(im) is incorrect. im.show() is I think what you're after, rather than trying to supply im as the title argument.

Could you expand on what problem you're seeing when showing multiple images? After inserting sleep 20 into a Pillow 9.0 installation, I don't see anything wrong.

imageshow.mov

[alv2017]

Using either im.show() or im.show(im) results in the same problem: after 20 s images disappear :)
(Try sliding over the images, let's say, after 30s)

[alv2017]

I believe that the perfect viewer function

a) allows to open one image or multiple images in one script;

b) multiple images can be viewed simultaneously, and user can switch from one image to another when viewing the images;

c) image is closed when the user closes it in the viewer;

d) temporary image files are deleted from the user machine.

[BrettRyland]

This also occurs with gwenview in KDE on KUbuntu versions as I posted here.
In addition to your perfect viewer function requirements, I would add that the viewer should be lightweight and with a clean interface. In my opinion, ImageMagick (via display instead of xdg-open) worked well for this.

[alv2017]

Actually I fixed all the viewers, and I made a DisplayViewer (which is ImageMagick) the default viewer. I will make a PR today or tomorrow.

[BrettRyland]

OK, sounds good. Thanks!