omarchycn/bin/omarchy-transcode-ascii

#!/bin/bash

# omarchy:summary=Transcode an image into ASCII/Unicode art text
# omarchy:group=transcode
# omarchy:name=ascii
# omarchy:args=<input-image.svg|png> <output-path> [--width <columns>] [--height <rows>] [--mode <braille|block>] [--threshold <percent>] [--invert]
# omarchy:examples=omarchy transcode ascii ~/logo.svg /tmp/logo.txt | omarchy transcode ascii ~/logo.png ~/.config/omarchy/branding/screensaver.txt --width 80

set -o pipefail

usage() {
  cat <<'EOF'
Usage: omarchy-transcode-ascii <input-image.svg|png> <output-path> [options]

Transcodes an image into ASCII/Unicode art text.

Options:
  -w, --width <columns>       Maximum output width in terminal columns (default: 80)
  -H, --height <rows>         Maximum output height in terminal rows (default: 26)
  -m, --mode <braille|block>  Output style (default: braille)
  -t, --threshold <percent>   Pixel threshold from 0-100 (default: 50)
      --invert                Treat light pixels as the logo instead of dark pixels
      --no-trim               Preserve surrounding whitespace/background
      --help                  Show this help
EOF
}

width=80
height=26
mode=braille
threshold=50
invert=false
trim=true
image_path=""
output_path=""

while (($# > 0)); do
  case "$1" in
  --help)
    usage
    exit 0
    ;;
  -w | --width)
    shift
    [[ -n $1 ]] || { echo "Missing value for --width" >&2; exit 1; }
    width="$1"
    ;;
  -H | --height)
    shift
    [[ -n $1 ]] || { echo "Missing value for --height" >&2; exit 1; }
    height="$1"
    ;;
  -m | --mode)
    shift
    [[ -n $1 ]] || { echo "Missing value for --mode" >&2; exit 1; }
    mode="$1"
    ;;
  -t | --threshold)
    shift
    [[ -n $1 ]] || { echo "Missing value for --threshold" >&2; exit 1; }
    threshold="$1"
    ;;
  --invert)
    invert=true
    ;;
  --no-trim)
    trim=false
    ;;
  -*)
    echo "Unknown option: $1" >&2
    usage >&2
    exit 1
    ;;
  *)
    if [[ -z $image_path ]]; then
      image_path="$1"
    elif [[ -z $output_path ]]; then
      output_path="$1"
    else
      echo "Unexpected argument: $1" >&2
      usage >&2
      exit 1
    fi
    ;;
  esac
  shift
done

if [[ -z $image_path || -z $output_path ]]; then
  usage >&2
  exit 1
fi

if [[ $mode != "braille" && $mode != "block" ]]; then
  echo "Invalid mode: $mode (expected braille or block)" >&2
  exit 1
fi

if [[ ! -f $image_path ]]; then
  echo "Logo file not found: $image_path" >&2
  exit 1
fi

if [[ $mode == "braille" ]]; then
  pixel_width=$((width * 2))
  pixel_height=$((height * 4))
else
  pixel_width=$width
  pixel_height=$((height * 2))
fi

alpha_range=$(magick -background none "$image_path" -alpha extract -format '%[fx:minima] %[fx:maxima]' info: 2>/dev/null) || {
  echo "Unable to read logo image: $image_path" >&2
  exit 1
}
read -r alpha_min alpha_max <<<"$alpha_range"

use_alpha=false
if awk -v min="$alpha_min" -v max="$alpha_max" 'BEGIN { exit !(min < 0.999 && max > min) }'; then
  use_alpha=true
fi

magick_args=(-background none "$image_path" -auto-orient)

if [[ $use_alpha == "true" ]]; then
  magick_args+=(-alpha extract -alpha off)
  if [[ $invert == "true" ]]; then
    magick_args+=(-negate)
  fi
else
  magick_args+=(-alpha remove -alpha off -colorspace Gray)
  if [[ $invert == "false" ]]; then
    magick_args+=(-negate)
  fi
fi

if [[ $trim == "true" ]]; then
  magick_args+=(-bordercolor black -border 1 -trim +repage)
fi

magick_args+=(-resize "${pixel_width}x${pixel_height}" -threshold "${threshold}%" -negate -compress none pbm:-)

tmp_output=$(mktemp)
trap 'rm -f "$tmp_output"' EXIT

if ! magick "${magick_args[@]}" | awk -v mode="$mode" '
  BEGIN {
    braille_base = 10240
    dot[0,0] = 1
    dot[0,1] = 2
    dot[0,2] = 4
    dot[1,0] = 8
    dot[1,1] = 16
    dot[1,2] = 32
    dot[0,3] = 64
    dot[1,3] = 128

    block["11"] = "█"
    block["10"] = "▀"
    block["01"] = "▄"
    block["00"] = " "
  }
  {
    sub(/#.*/, "")
    for (i = 1; i <= NF; i++) {
      token[++token_count] = $i
    }
  }
  END {
    if (token[1] != "P1") {
      exit 1
    }

    width = token[2]
    height = token[3]
    pixel_offset = 4
    row_step = (mode == "braille") ? 4 : 2

    for (y = 0; y < height; y += row_step) {
      line = ""
      if (mode == "braille") {
        for (x = 0; x < width; x += 2) {
          code = 0
          for (dy = 0; dy < 4; dy++) {
            for (dx = 0; dx < 2; dx++) {
              if (y + dy < height && x + dx < width) {
                pixel = token[pixel_offset + ((y + dy) * width) + x + dx]
                if (pixel == 1) {
                  code += dot[dx,dy]
                }
              }
            }
          }

          if (code == 0) {
            line = line " "
          } else {
            line = line sprintf("%c", braille_base + code)
          }
        }
      } else {
        for (x = 0; x < width; x++) {
          top = token[pixel_offset + (y * width) + x]
          bottom = (y + 1 < height) ? token[pixel_offset + ((y + 1) * width) + x] : 0
          line = line block[top bottom]
        }
      }
      sub(/[ ]+$/, "", line)
      lines[++line_count] = line
    }

    first = 1
    while (first <= line_count && lines[first] ~ /^[ ]*$/) {
      first++
    }

    last = line_count
    while (last >= first && lines[last] ~ /^[ ]*$/) {
      last--
    }

    for (i = first; i <= last; i++) {
      print lines[i]
    }
  }
' >"$tmp_output"; then
  echo "Unable to convert logo image: $image_path" >&2
  exit 1
fi

if [[ ! -s $tmp_output ]]; then
  echo "No logo pixels found in: $image_path" >&2
  exit 1
fi

mkdir -p "$(dirname "$output_path")"
cp "$tmp_output" "$output_path"
echo "Wrote ASCII art to $output_path"