generate color scheme from image for tilix

shwal

err_usage() {
	printf 'Usage: %s [-l] [-n name] [-c comment] image\n' "$0" >&2
	exit 1
}

name=Custom
comment=
light_theme=0

while getopts :n:c:l opt; do
	case $opt in
	(n) name=$OPTARG ;;
	(c) comment=$OPTARG ;;	
	(l) light_theme=1 ;;
	(*) err_usage
	esac
done

shift $((OPTIND - 1))
if test $# -ne 1; then
	err_usage
fi

filter='
trim=end_frame=1,
scale=iw/4:ih/4,
palettegen=17:0,
crop=16:2:0:0,
split[dark],
hue=s=1.5[light],
[dark][light]concat
'

ffmpeg	-loglevel error \
	-i "$1" \
	-filter_complex "$filter" \
	-f rawvideo \
	-pix_fmt argb \
	- \
| od -A n -t u1 -v \
| awk '
{
	for (i = 1; i <= NF; i += 4) {
		num_colors++
		r[num_colors] = $(i + 1)
		g[num_colors] = $(i + 2)
		b[num_colors] = $(i + 3)
		
		unique[r[num_colors], g[num_colors], b[num_colors]]
	}
}

END {
	for (i in unique)
		num_unique++
		
	if (num_unique < 32) {
		system("echo fewer colors than required >&2")
		exit 1
	}


	for (i = 2; i <= 9; i++)
		copy(i + 7, i)

	if ('$light_theme' == 1) {
		copy(1, 8)
		copy(1, 16)
		copy(17, 1)
		lighten(1, 0.85)
		copy(17, 9)
		darken(9, 0.4)

		for (i = 2; i <= 7; i++) {
			copy(i + 39, i)
			copy(i + 39, i + 8)
		}
	}
	else {
		for (i = 10; i <= 16; i++)
			copy(i - 8, i)

		if (r[1] >= 0x10)
			darken(1, 0.4)

		blend(8, 0xEE, 0xEE, 0xEE)
		copy(8, 9)
		darken(9, 0.3)
		blend(16, 0xEE, 0xEE, 0xEE)
	}

	for (i = 1; i <= 16; i++) {
		printf "%s", color_block(i) > "/dev/tty"

		if (i == 8 || i == 16)
			print "" > "/dev/tty"
	}

	for (i = 1; i <= 16; i++)
		print color_code(i)
}

function color_code(i) {
	return sprintf("#%02x%02x%02x", r[i], g[i], b[i])
}

function color_block(i) {
	return sprintf("\33[48;2;%d;%d;%dm    \33[m",
		r[i], g[i], b[i])
}

function copy(from, to) {
	r[to] = r[from]
	g[to] = g[from]
	b[to] = b[from]
}

function lighten(i, amount) {
	r[i] = int(r[i] + (255 - r[i]) * amount)
	g[i] = int(g[i] + (255 - g[i]) * amount)
	b[i] = int(b[i] + (255 - b[i]) * amount)
}

function darken(i, amount) {
	r[i] = int(r[i] * (1 - amount))
	g[i] = int(g[i] * (1 - amount))
	b[i] = int(b[i] * (1 - amount))
}

function blend(i, r2, g2, b2) {
	r[i] = int((r[i] + r2) / 2)
	g[i] = int((g[i] + g2) / 2)
	b[i] = int((b[i] + b2) / 2)
}
' \
| jq -R -n \
	--arg name "$name" \
	--arg comment "$comment" '
[inputs] as $palette | {
	$name,
	$comment,
	"use-theme-colors": false,
	"foreground-color": $palette[15],
	"background-color": $palette[0],
	$palette
}
'

# vim: ft=sh