fix imgcat to be able to display images on tmux https://gitlab.com/gnachman/iterm2/issues/3898#note_14097715

imgcat

#!/bin/bash

# tmux requires unrecognized OSC sequences to be wrapped with DCS tmux;
# <sequence> ST, and for all ESCs in <sequence> to be replaced with ESC ESC. It
# only accepts ESC backslash for ST.
function print_osc() {
    if [[ -n $TERM ]] ; then
        printf "\033Ptmux;\033\033]"
    else
        printf "\033]"
    fi
}

function print_csi() {
    printf "\033["
}

# More of the tmux workaround described above.
function print_st() {
    if [[ -n $TERM ]] ; then
        printf "\a\033\\"
    else
        printf "\a"
    fi
}

# Return the height of the image, or 200 if imagemagick is unavailable.
function get_height() {
    identify -format "%h" - 2>/dev/null || echo 200
}

# print_image filename inline base64contents print_filename
#   filename: Filename to convey to client
#   inline: 0 or 1
#   base64contents: Base64-encoded contents
#   print_filename: If non-empty, print the filename 
#                   before outputting the image
function print_image() {
    VERSION=$(base64 --version 2>&1)
    if [[ "$VERSION" =~ fourmilab ]]; then
      BASE64ARG=-d
    elif [[ "$VERSION" =~ GNU ]]; then
      BASE64ARG=-di
    else
      BASE64ARG=-D
    fi

    local -i HEIGHT=$(printf "%s" "$3" | base64 $BASE64ARG | get_height)
    HEIGHT=$(( (HEIGHT + 19) / 20 ))

    for (( I = 0; I < $HEIGHT; I++ )); do
      printf "\n"
    done
    print_csi
    printf "?25l"
    print_csi
    printf "${HEIGHT}F"

    print_osc
    printf '1337;File='
    if [[ -n "$1" ]]; then
      printf 'name='`printf "%s" "$1" | base64`";"
    fi

    printf "%s" "$3" | base64 $BASE64ARG | wc -c | awk '{printf "size=%d",$1}'
    printf ";inline=$2"
    printf ";height=$HEIGHT"
    printf ":"
    printf "%s" "$3"
    print_st
    printf '\n'
    if [[ -n "$4" ]]; then
      echo $1
    fi

    print_csi
    printf "${HEIGHT}E"
    print_csi
    printf "?25h"
}

function error() {
    echo "ERROR: $*" 1>&2
}

function show_help() {
    echo "Usage: imgcat [-p] filename ..." 1>& 2
    echo "   or: cat filename | imgcat" 1>& 2
}

## Main

if [ -t 0 ]; then
    has_stdin=f
else
    has_stdin=t
fi

# Show help if no arguments and no stdin.
if [ $has_stdin = f -a $# -eq 0 ]; then
    show_help
    exit
fi

# Look for command line flags.
while [ $# -gt 0 ]; do
    case "$1" in
    -h|--h|--help)
        show_help
        exit
        ;;
    -p|--p|--print)
        print_filename=1
        ;;
    -*)
        error "Unknown option flag: $1"
        show_help
        exit 1
        ;;
    *)
        if [ -r "$1" ] ; then
            has_stdin=f
            print_image "$1" 1 "$(base64 < "$1")" "$print_filename"
        else
            error "imgcat: $1: No such file or directory"
            exit 2
        fi
        ;;
    esac
    shift
done

# Read and print stdin
if [ $has_stdin = t ]; then
    print_image "" 1 "$(cat | base64)" ""
fi

exit 0

This is great! Thanks!

Very nice!

Doesn't work for me with tmux 3.1b, Mac OS 10.15 😕 (I just get a blank area about the size of the image)

Same for me. :-(

Works for me ... images show up at least for a while. If I navigate away or do anything else that (I assume) causes tmux to refresh the pane I get an empty square as well. But for my use case this works. Thanks!

@thlorenz what tmux version did you using?

With updated versions of FzF / Tmux / iTerm this works.

Well, on images up to to 2048x1277 (or something like this) this is working fine but when the image is too much above that then it simply shows a black "img".

Was wondering some way to "resize" images before invoking this, the original imcat has some flags for width/height but they don't work here:

 $  imgcat -h
Usage:
        /opt/homebrew/bin/imgcat [--width=<columns> --height=<rows>|--no-resize] [--no-preserve-aspect-ratio]
                                 [--half-height] [--depth=(8|256|24bit|iterm2)] IMAGE
        /opt/homebrew/bin/imgcat --version
        /opt/homebrew/bin/imgcat --help

Awesome script btw.. a little bit more this possibly could be used with fzf preview too which would be really nice.

Yeah most likely that's why I get those black "imgs", looking into fzf-preview.sh code it uses those Width/Height flags to resize the img.

ie: outside of tmux

Now in tmux (here I'm not even using FzF but just previewing the img)

 $  file wallhaven-yxmrxk.jpg
wallhaven-yxmrxk.jpg: JPEG image data, Exif standard: [TIFF image data, little-endian, direntries=6, orientation=upper-left, xresolution=86, yresolution=94, resolutionunit=2], baseline, precision 8, 3840x2400, components 3

I'm trying to leverage something from ImageMagick here. This quick test worked successfully (inside tmux).

I could wrapper both in a script however it's losing img quality which doesn't seem to happen w/ original imagecat even when inside a FzF preview, no idea how they are shrinking img keeping a good img quality. Anyway, this quick and dirty script worked in tmux:

#!/bin/bash

# Input image file
input_image="$1"

# Resize the image using 'convert' and pipe it to the main script
convert "$input_image" -resize "800x600>" jpg:- 2> /dev/null| imgcat

Anyway, just sharing what I did in case it’s useful—this helped me deal with oversized images, though it came at the cost of some quality