Auto PNG Compressor

This project provides a tool to automatically compress PNG files in a specified directory using pngquant. The tool watches the directory for new PNG files, compresses them, and renames the compressed files with a _compr suffix. After compression, the original files are deleted.

The need to support ES modules in this application primarily stems from the fact that pngquant-bin is an ES module. ES modules use a different syntax and have different behaviors compared to CommonJS modules, which is why ts-node and TypeScript need to be configured to handle ES modules correctly.

ES Modules require either the file to have a .mjs extension or to set "type": "module" in package.json.

Features

• Watches a specified directory for new PNG files.
• Compresses PNG files using pngquant.
• Renames compressed files with a _compr suffix.
• Logs file size before and after compression.
• Deletes original files after compression.

Prerequisites

• node.js (v20 or higher)

• npm (v10.2.4)

• libimagequant

  via Homebrew for macOS,

  libimagequant is typically bundled with pngquant

  brew install pngquant

  via apt-get for Debian distributions

  sudo apt-get install libimagequant-dev

Installation

1. Clone the repository or download the source code.

   git clone https://github.com/salcad/auto-png-compressor.git
   cd auto-png-compressor

2. Install the required npm packages.

   npm install

Usage

1. Create a .env file in the root of the project and update the WATCHED_DIR and COMPRESSION_LEVEL variables to match your needs.

   WATCHED_DIR=/path/to/your/folder
   COMPRESSION_LEVEL=50-70

2. Run the script in development mode.

   npm run dev

3. To build and run the project in production mode:

   npm run build
   npm start

4. Run test

    npm test

Dependencies

• chokidar: A file watcher for Node.js.
• pngquant-bin: A pngquant binary for use in Node.js.

Development Dependencies

• ts-node: TypeScript execution environment for Node.js.
• typescript: TypeScript language and compiler.
• jest: JavaScript testing framework.
• ts-jest: Jest transformer for TypeScript.
• @types/node: TypeScript definitions for Node.js.
• @types/jest: TypeScript definitions for Jest.

TypeScript Configuration

Ensure your tsconfig.json includes the following configuration to support ES modules and ts-node:

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "ESNext",
    "moduleResolution": "node",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "typeRoots": ["./node_modules/@types", "./types"],
    "resolveJsonModule": true,
    "experimentalDecorators": true
  },
  "ts-node": {
    "transpileOnly": true,
    "esm": true,
    "experimentalSpecifierResolution": "node"
  },
  "include": ["src/**/*", "types/**/*.d.ts"],
  "exclude": ["node_modules", "dist", "tests"]
}