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@martinb3
Created Sep 9, 2021
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#!/bin/bash
# All credit goes to https://gist.github.com/alisdair/ffc7c884ee36ac132131f37e3803a1fe for the original script.
# This is only a slight modification to allow for a scrolling version of the transform.
# Generate a `:infinite-something:` Slack emoji, given a reasonable image
# input. I recommend grabbing an emoji from https://emojipedia.org/
set -euo pipefail
# Number of frames of scrolling
count=10
# Max pixels to move while scrolling
delta=12
if [ $# -eq 0 ]; then
echo "Usage: $0 input.png"
exit 1
fi
input=$1
cd "$(dirname "$input")"
filename=$(basename -- "$input")
# Add 10% padding to width and height, then scale to 128x128
width=$(identify -format "%w" "$filename")
height=$(identify -format "%h" "$filename")
new_width=$(( width + width / 10 ))
new_height=$(( height + height / 10 ))
extended="${filename%.*}-extended.png"
convert \
-gravity center \
-background none \
-extent ${new_width}x${new_height} \
-geometry 128x128 \
"$filename" \
"$extended"
montage="${filename%.*}-montage.png"
montage \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
"${extended}" \
-geometry -8-8+0 -adjoin \
"${montage}"
# Generate some shaky frames
frame="${filename%.*}-frame"
n=0
while [ "$n" -lt "$count" ]; do
# Scroll the image
x=$((n * delta))
y=$((n * delta))
# Ensure coordinates are of the form +3 or -4
[ "$x" -ge 0 ] && x="+$x"
[ "$y" -ge 0 ] && y="+$y"
# Shake the image!
convert "$montage" -roll "$x$y" -background none -flatten "$frame"-"$n".gif
n=$((n + 1))
done
# Combine the frames into a GIF
gif="infinite-${filename%.*}.gif"
convert -background none -dispose Background -delay 1x30 -loop 0 "${frame}"-*.gif "$gif"
# Clean up
rm "$extended" "${montage}" "${frame}"-*.gif
# We did it y'all
echo "Created $gif. Enjoy!"
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