pngquant / pngopt で指定したフォルダ内のpng画像を再圧縮する

pngopt-all.sh

#!/usr/bin/env bash

# エラーが発生した場合、およびパイプラインでエラーが発生した場合にスクリプトを終了する
set -e
set -o pipefail

# --- ヘルプメッセージ ---
usage() {
  cat <<EOF
Usage: $(basename "$0") [OPTIONS] <directory> <compression_level>

Re-compresses all PNG files in a directory using pngquant and optipng.
Original files are moved to a subdirectory named '_original'.

Arguments:
  <directory>         The target directory containing PNG files.
  <compression_level> The compression level (1-9, where 9 is maximum compression).

Options:
  -n, --dry-run       Show what would be done, without actually modifying any files.
  -h, --help          Display this help message and exit.
EOF
  exit 1
}

# --- 初期値 ---
DRY_RUN=0

# --- オプション解析 ---
# getoptsではなく、より柔軟なループを使用
while [[ $# -gt 0 ]]; do
  case "$1" in
    -n|--dry-run)
      DRY_RUN=1
      shift # 引数をシフト
      ;;
    -h|--help)
      usage
      ;;
    --)
      shift # -- の後を引数として扱う
      break
      ;;
    -*)
      echo "Unknown option: $1"
      usage
      ;;
    *)
      break # オプション以外の引数が見つかったらループを抜ける
      ;;
  esac
done

# --- 引数のチェック ---
if [ "$#" -ne 2 ]; then
  echo "Error: Missing directory or compression level argument."
  usage
fi

TARGET_DIR=$1
COMPRESSION_LEVEL=$2
COMPRESSED_DIR="$(dirname "$TARGET_DIR")/$(basename "$TARGET_DIR")_compressed"

# --- 依存関係のチェック ---
for cmd in pngquant optipng find mv mkdir basename; do
  if ! command -v "$cmd" &> /dev/null; then
    echo "Error: Required command '$cmd' is not available in your PATH."
    exit 1
  fi
done

# --- 入力値の検証 ---
if [ ! -d "$TARGET_DIR" ]; then
  echo "Error: Directory '$TARGET_DIR' not found."
  exit 1
fi

if ! [[ "$COMPRESSION_LEVEL" =~ ^[1-9]$ ]]; then
  echo "Error: Compression level must be a number between 1 and 9."
  exit 1
fi

# --- ドライランの表示 ---
if [ "$DRY_RUN" -eq 1 ]; then
  echo "*** This is a DRY RUN. No files will be changed. ***"
  echo "----------------------------------------------------"
fi

echo "Target directory:          $TARGET_DIR"
echo "Compression level:         $COMPRESSION_LEVEL"
echo "Compression directory:     $COMPRESSED_DIR"
echo ""

# --- 処理の実行 ---
if [ "$DRY_RUN" -eq 0 ]; then
  mkdir -p "$COMPRESSED_DIR"
fi

processed_files=0
# findで見つかったファイルを配列に格納してからループ処理
mapfile -t -d '' files < <(find "$TARGET_DIR" -type f -iname "*.png" -print0)

for file in "${files[@]}"; do
  filename=$(basename "$file")
  # 相対パスを取得してサブディレクトリ構造を保持
  relative_path="${file#$TARGET_DIR/}"
  convert_file="${COMPRESSED_DIR}/${relative_path}"
  working_dir=$(dirname "$convert_file")

  if [ "$DRY_RUN" -eq 1 ]; then
    echo "[DRY RUN] Would re-compress to '$convert_file' with compression level $COMPRESSION_LEVEL"
  else
    echo "Processing: $relative_path"
    # 1. 作業ディレクトリを作成
    if ! mkdir -p "$working_dir"; then
      echo "Error: Failed to create working directory '$working_dir'"
      continue
    fi
    # 2. 再圧縮 (pngquant + optipng)
    temp_file="${convert_file}.tmp"
    if pngquant --quality=65-80 --output "$temp_file" "$file" 2>/dev/null && \
       optipng -o"$COMPRESSION_LEVEL" -quiet "$temp_file" 2>/dev/null && \
       mv "$temp_file" "$convert_file"; then
      echo "✓ Successfully processed: $relative_path"
    else
      echo "Error: Failed to compress '$relative_path'. Restoring original file."
      # 失敗した場合、一時ファイルを削除してオリジナルファイルを復元
      rm -f "$temp_file"
      continue
    fi
  fi
  processed_files=$((processed_files + 1))
done

echo "----------------------------------------------------"
if [ "$processed_files" -eq 0 ]; then
  echo "No PNG files found to process."
else
  if [ "$DRY_RUN" -eq 1 ]; then
    echo "Dry run complete. Found $processed_files PNG file(s)."
  else
    echo "Successfully re-compressed $processed_files PNG file(s)."
  fi
fi