Title not displayed when using Image.show(title='...')

[FiReTiTi]

What did you do?

I have a NumPy array representing an image that I import using ``, and then I display it using the method show(title='A Title').

[some code....]
from PIL import Image
imgIm = Image.fromarray(MyArrayImage)
imgIm.show(title="Image")

What did you expect to happen?

I expected to see Image written as a title of the window.

What actually happened?

I got a random text.

What are your OS, Python and Pillow versions?

• OS: MacOSX
• Python: 3.8.7
• Pillow: 8.3.2

[nulano]

This function internally just (indirectly) calls PIL.ImageShow.show.

From https://pillow.readthedocs.io/en/stable/reference/ImageShow.html#PIL.ImageShow.show:

title – Optional title. Not all viewers can display the title.

From the provided list of image viewers, only one is listed as supporting title: https://pillow.readthedocs.io/en/stable/reference/ImageShow.html#PIL.ImageShow.UnixViewer.XVViewer

class XVViewer

The X Viewer xv command. This viewer supports the title parameter.

Edit: As discussed below, the display viewer now has now been updated to support the title parameter.

[FiReTiTi]

Thanks, so it is a very limited feature.
Wouldn't it deserve to be flagged/asserted when used if the viewer is not the proper one?

[radarhere]

Ok, how about #5743, which would raise a warning for you, "title argument is not supported by this viewer"?

[hugovk]

I don't know if a warning is a good idea:

Say a project uses show and then one person uses it on Linux -- no warning -- but then another uses it on Mac and gets a warning.

There's nothing they can do except maybe raise an issue with that project.

What can the project do? Add some code to only pass a title when on Linux? That's not strictly correct because maybe some Linux viewer will add title at some point.

[radarhere]

Good point, thanks. Closing #5743

[radarhere]

@FiReTiTi given that discussion, is there anything further you'd like to be done here?

[FiReTiTi]

I have an answer about why it does not work, but my feeling is that a fix is necessary.
A feature/option that works only for a single viewer only on Linux seems too limited/restricted and is highly confusing.

What can the project do? Add some code to only pass a title when on Linux? That's not strictly correct because maybe some Linux viewer will add title at some point.

It seems the best option (IMHO).

[radarhere]

I don't think it's possible to implement this feature for all platforms. We could set the name of the temporary file to the title, but trying to filter out invalid filenames would then become its own problem (see https://stackoverflow.com/a/1976050/4093019 and #3450).

[jrazik]

I just face that "bug" today and despite the title option is only used for xv, the display command also knows this option.
Thus just change the get_command_ex function line 192 of ImageShow.py to this will be ok (enough ok for me).

    def get_command_ex(self, file, title=None, **options):
        command = executable = "display"
        if title:
            command += f" -title {quote(title)}"
        return command, executable

[radarhere]

Ok, I've created PR #5788 to add the title option for "display", as you suggest.

[hugovk]

Is there any indication this option has been around long enough that it won't fail on some (modernish) systems?

[radarhere]

https://web.archive.org/web/20120408021811/http://linux.die.net/man/1/display indicates that it has been there since at least 2012.

[hugovk]

Thank you all, merged! Let's close this unless there's more concrete steps to take.

[nulano]

While updating my comment above (#5739 (comment)) I noticed #5788 didn't update the documentation so I have created #5790 to do that.