webp-thumbnailer

#!/bin/bash
set -euo pipefail

# See https://askubuntu.com/questions/617047/how-to-preview-dds-and-webp-images-on-nautilus
# Note: this is obsoleted by package webp-pixbuf-loader in Ubuntu >= 22.04


if [ $# -eq 0 ]; then
    cat >&2 <<EOM
usage: $(basename "$0") --install
usage: $(basename "$0") INFILE MAX_DIMENSION OUTFILE

Note: this is obsoleted by package webp-pixbuf-loader
EOM
    exit 1
fi

if [[ $1 == --install ]]; then
    set -x
    sudo cp -v "$0" /usr/local/bin/webp-thumbnailer

    # mkdir -vp ~/.local/share/thumbnailers
    #tee ~/.local/share/thumbnailers/webp.thumbnailer <<EOM
    tee /usr/share/thumbnailers/webp.thumbnailer <<EOM
[Thumbnailer Entry]
Exec=/usr/local/bin/webp-thumbnailer %i %s %o
MimeType=image/webp;
EOM

    set +x
    echo "OK, installed"
    exit
fi

run() {
    echo >&2 "+ $*"
    "$@"
}

strInFile="$1"
nMaxDimension="$2"
strOutFile="$3"
strInfo="$(run webpinfo "$strInFile")"
strSize="$(echo "$strInfo" | grep Canvas | sed -r 's"Canvas size (.*) x (.*)"\1\t\2"')"
nWidth="$(echo "$strSize" | cut -f1)"
nHeight="$(echo "$strSize" | cut -f2)"
if ((nWidth>nHeight)); then
    nNewWidth=$nMaxDimension
    nNewHeight=$(bc <<< "scale=10;f=$nHeight*($nNewWidth/$nWidth);scale=0;f/1")
else
    nNewHeight=$nMaxDimension
    nNewWidth=$(bc <<< "scale=10;f=$nWidth*($nNewHeight/$nHeight);scale=0;f/1")
fi
run dwebp "$strInFile" -scale "$nNewWidth" "$nNewHeight" -o "$strOutFile"