support ueberzug image displayer

[seebye]

Überzug is a command line util which allows to draw images on terminals by using child windows.
It has some advantages over w3mimgdisplay, e.g.:

• it has no memory leak (/ unlimited cache) (related: w3mimgdisplay consumes a lot of memory #451)
• no race conditions as a new window is used to display images
• tmux support
• faster as the current w3mimgdisplay implementation as the communication goes only in one direction

More: https://github.com/seebye/ueberzug#%C3%9Cberzug

ISSUE TYPE

• Improvement/feature implementation

RUNTIME ENVIRONMENT

• Operating system and version: Debian Buster
• Terminal emulator and version: xterm / alacritty
• Python version: 2.7.15 (default, Jul 28 2018, 11:29:29) [GCC 8.1.0]
• Ranger version/commit: ranger-master v1.9.1-173-gd37e4b2c
• Locale: None.None

CHECKLIST

• The CONTRIBUTING document has been read [REQUIRED]
• All changes follow the code style [REQUIRED]
• All new and existing tests pass [REQUIRED]
• Changes require config files to be updated
  • Config files have been updated
• Changes require documentation to be updated
  • Documentation has been updated
• Changes require tests to be updated
  • Tests have been updated

DESCRIPTION

MOTIVATION AND CONTEXT

w3mimgdisplay does not work with alacritty, tmux is also not supported

TESTING

IMAGES / VIDEOS

[toonn]

Looks pretty cool for a first contribution. Does überzug only support python 3.x? That's somewhat unfortunate. If it's not could you run it with the same python that's running ranger, or just the python on the PATH?

[seebye]

Does überzug only support python 3.x? That's somewhat unfortunate. If it's not could you run it with the same python that's running ranger, or just the python on the PATH?

I used python3 features like asyncio to avoid dealing with thread safety, so it won't run with python2.

[toonn]

Is the threading module an option, afaik that's been backported?

[jaelpark]

Somehow it always draws the picture to the upper left corner, regardless of the given x,y parameters. Happens both in ranger and with this simpler demonstration (using termite):

from subprocess import Popen,PIPE

p = Popen(['python3','-m','ueberzug','layer'],stdin=PIPE,universal_newlines=True);
p.stdin.write('{"action":"add","x":500,"y":200,"identifier":"preview","path":"image.png"}\n');
p.stdin.flush();
input("...");

[seebye]

@jaelpark I think this belongs to https://github.com/seebye/ueberzug/issues.
Termite is not in the debian testing repository, but I guess that termite does not support extracting the terminal size in pixels via termios.TIOCGWINSZ.
Therefore the font size can't be determied.
Another way to optain the terminal size isn't implemented currently, but it's easily fixable by using python-Xlib.
You can test whether your terminal emulator supports extracting the terminal size in pixels by executing the following code:

#!/usr/bin/env python3
import sys
import struct
import fcntl
import termios

farg = struct.pack("HHHH", 0, 0, 0, 0)
fd_stdout = sys.stdout.fileno()
fretint = fcntl.ioctl(fd_stdout, termios.TIOCGWINSZ, farg)
rows, cols, xpixels, ypixels = struct.unpack("HHHH", fretint)
print('rows', rows, 'cols', cols, 'xpixels', xpixels, 'ypixels', ypixels)

@toonn Honestly, I don't really wan't to support python2.
Python3 should be installed on the most linux systems anyways and
if it's not it shouldn't be a problem as people were already willing to install an entire browser to display images with ranger.
So it would just increase the effort to maintain ueberzug in my opinion.

Edit: You're right didn't saw the additonal package in debians repository.

[toonn]

Entire browser? w3m-img doesn't depend on w3m.

[jaelpark]

@seebye I created a quick fix and opened a PR, see if it's something you want to merge. At least the problem with termite is fixed. This could be configurable, whether to get the dimensions with Xlib or using the original method.

[toonn]

This doesn't work for me. ueberzug doesn't work on the command line either. Using a virtualenv with python 3.7 and the terminology terminal emulator.

[seebye]

In the newest version there are some changes for python3.7.
(The preview worked for me after these modifications in terminology in a python3.7 virtualenv)
However your error message looks like the window lacks the _NET_WM_PID property?
Ueberzug can't work without it as it uses the pid to determine the window id.

[toonn]

I have no idea why the property would be missing. No funny business on my end afaik.

[seebye]

I think it should work with version 6 if it's not terminology itself which lacks the property.

[toonn]

It works with v6 yes. It seems to work quite nicely. The quality is a little less than with native terminology previews but I'm not sure that can be achieved in a method compatible with multiple terminals. It's mostly noticeable with text:

I did notice a problem though. I was testing the method and wanted to compare to the terminology method on that screenshot of text because I thought I noticed a quality difference. The ueberzug window didn't close, it just stayed open overlapping that part of ranger. Switching back to the ueberzug method didn't help either, the new ueberzug windows were drawn under the one that stuck. I really think this should be fixed before we include the method in the release.

[seebye]

I really think this should be fixed before we include the method in the release.

On the latest version of ranger the preview image also stays if you switch from terminology to e.g. w3m.
So I also implemented the quit method for the preview methods which still missed it.

[toonn]

The previous problem was fixed, so we're making progress but I ran into another problem when ueberzug tries to preview an svg I get this error:

It's probably not possible to have ueberzug preview svg's but it shouldn't mess up the interface. Either log the mesasge with self.fm.notify or suppress it entirely.

[toonn]

For me the image never stayed when I switched from terminology to another method. If you did have that problem then that sounds like a good fix though.

[seebye]

I enabled the redirection of stderr to /dev/null.
So errors should be suppressed now.

[toonn]

This might make troubleshooting a little harder when people do expect a preview but it's an ok fix imo.

And I checked again and indeed changing away from the terminology method left an image too.

[toonn]

This is an awesome first contribution. Thanks for the work. I'm gonna allow for a little time for another team member to check out the changes but this is probably going in the next release. 👍

[vifon]

Looks really interesting! Sadly I cannot get it to work. I'm using set preview_images_method ueberzug and I'm running ranger with Python 3. Anything else I need to know? Can a tiling window manager (XMonad) be the cause?

[vifon]

It also needs documentation in the rc.conf comment and a new allowed value here.

[toonn]

@vifon, you did actually install ueberzug first, right? And good catch about the documentation and the ALLOWED_VALUES, although that seems to be a misnomer because I was able to test and afair tab complete the ueberzug method without any problem : )

[sooriravindra]

I am using suckless terminal on Arch, ueberzug sample bash script displays image using the terminal. However ranger fails to display the image in preview.

Installed both using "sudo pip install ranger ueberzug"

ranger version: ranger 1.9.2
Python version: 3.7.3 (default, Jun 24 2019, 04:54:02) [GCC 9.1.0]

[toonn]

You need the master version of ranger this is not in the release.

[sooriravindra]

I tried with the master version from github, same effect.

I also tried ranger-git in AUR, no luck :(

[toonn]

You did set preview_images_method ueberzug, right? Also, you're sure you were running the master version and not the installed one?

[sooriravindra]

Yes, my ~/.config/ranger/rc.conf has

set preview_images true
set preview_images_method ueberzug

And yeah I removed the earlier ranger and cloned master and did a make install. The preview window is blank.

[toonn]

@seebye, could you chime in? I have no idea why it'd work in the terminal but not ranger.

[ivomac]

@sooriravindra, I have the same setup as you, st, ranger-git from AUR and ueberzug from pip. I can see preview images but only if they fit inside the preview pane. It seems like the images are not resized to fit.

Can you check if you can preview a low enough resolution image?

Edit: I checked with urxvt and kitty and the same happens.

[sooriravindra]

@ivomac that seems like it, I was trying to preview images that don't fit in the preview window. Now when I tried a smaller image, the preview works.

The issue seems to be with resizing.

[toonn]

Hmm, maybe try uninstalling pillow-simd and installing pillow instead?

[ivomac]

I tried uninstalling pillow-simd and installing pillow but now ueberzug complains it is missing pillow-simd. Is there a way to tell it to use pillow?

This doesn't seem to be an issue with ranger. Opening an image with ueberzug on the terminal and forcing a resize using max_width and max_height gives a segmentation fault.

Used bash script:

#!/usr/bin/bash

source "`ueberzug library`"

ImageLayer 0< <(
	ImageLayer::add [identifier]="example" [max_width]="200"
[max_height]="200" [x]="0" [y]="0" [path]="$1"
	read
	ImageLayer::remove [identifier]="example"
)

images smaller than 200x200 are displayed correctly, larger ones give the error

/usr/lib/python3.7/site-packages/ueberzug/lib/lib.sh:
line 41: 11648 Segmentation fault (core dumped)
ueberzug layer -p bash "$@"

[seebye]

I tried uninstalling pillow-simd and installing pillow but now ueberzug complains it is missing pillow-simd. Is there a way to tell it to use pillow?

Try to install ueberzug by using pip it shouldn't complain then.
(/ pillow and pillow-simd should be exchangeable if you install it with pip)
(Also someone made the effort to package ueberzug with pillow instead of pillow-simd.
https://aur.archlinux.org/packages/python-ueberzug-nosimd-git/ )

[ivomac]

python-ueberzug-nosimd-git worked perfectly. Thank you!

[toonn]

@seebye, is there any chance you'd consider making pillow the default dependency? We're gonna get a bunch of issue reports about this when ueberzug makes it into the next release.

It'd be far easier if it just always works and we mention you might be able to get a speed improvement with pillow-simd.

[seebye]

@toonn Sure, I guess. I'm busy right now, so I'm likely doing it not until next week.

[sooriravindra]

@seebye python-ueberzug-nosimd-git works great. However the pip install complains if pillow-simd is not installed ( I had pillow installed).

Thank you!

[edjorqs]

Hi, when I try to preview an image in ranger, at the bottom of the terminal appears
[Errno 13] Permission denied 'ueberzug'
Any hint? I have searched everywhere but I don't know what could I do.
I use gentoo, and if I do source "`ueberzug library`" before running ranger, nothing appears at the preview.

[toonn]

What do you mean by source? Ueberzug is definitely not designed to be sourced by a shell. How did you install ueberzug?

[edjorqs]

I installed following the instructions from ueberzug's github, and by source, I mean this in bash:
source "`ueberzug library`"

[toonn]

Does that at least print the path to the library?

[edjorqs]

Hey, suddenly, now it shows images whose resolution is smaller than the right side of the terminal, check this out:

But nothing happens with a bigger image:

And all I have as config is the default config with ueberzug instead of w3m

[sooriravindra]

@eduardoejorqueras Have you tried making Ueberzug to use pillow instead of pillow-simd?

[edjorqs]

@sooriravindra thank you, I just uninstalled pillow-simd and works very nice 😄 , here the evidence:

[remlap]

Hi I recently did a fresh install and now ueberzug fails to line up properly.

[seebye]

@remlap The font size & padding is guessed. See: #1284 (comment)
Your terminal doesn't fit the assumptions.
You need to remove the menu bar & the scrollbar.

[remlap]

It would work previously fine.

[seebye]

@toonn I released a new version (on pypi/pip) which uses pillow instead of pillow-simd.

[toonn]

@seebye, thank you a lot for this. I understand a more performant default is attractive so I would've totally understood if you said no. This'll probably save us a ton of issue reports ❤️

[gxt-kt]

Hi, when I try to preview an image in ranger, at the bottom of the terminal appears [Errno 13] Permission denied 'ueberzug' Any hint? I have searched everywhere but I don't know what could I do. I use gentoo, and if I do source "ueberzug library" before running ranger, nothing appears at the preview.

Can you share that how do you resolve the problem? I meet the same problem that show [Errno 13] Permission denied 'ueberzug in ranger. I see the ueberzug website has stoped maintained and no issues.