ppm-parser

A lightweight library for parsing PPM (Portable Pixmap) image files in P3 and P6 formats. This package allows users to extract pixel data from PPM images and provides a simple and extensible API for developers to build upon.

Installation

To install the package, use your favorite package manager:

# Using npm
npm install ppm-parser

# Using Yarn
yarn add ppm-parser

# Using pnpm
pnpm add ppm-parser

Usage

This library provides an easy-to-use API for parsing PPM images. It supports both P3 (plain text) and P6 (binary) formats.

Example: Parsing a PPM Image

import parsePPM from 'ppm-parser';

// Load your PPM data into a Uint8Array (e.g., from a file)
const ppmData = new Uint8Array([
    // Example data for demonstration purposes
]);

// Parse the PPM data
const { width, height, values } = parsePPM(ppmData);

console.log('Image Width:', width);
console.log('Image Height:', height);
console.log('Pixel Values:', values);

Supported Formats

• P3: Plain-text PPM files with pixel data represented as ASCII numbers.
• P6: Binary PPM files with raw pixel data.

API Reference

parsePPM(data: Uint8Array): PPMImage

• Description: Automatically detects and parses PPM data in either P3 or P6 format.
• Parameters:
  • data: A Uint8Array containing the PPM file's binary data.
• Returns: A PPMImage instance containing:
  • width: The width of the image.
  • height: The height of the image.
  • pixelData: A Uint8Array with interleaved RGB values.
  • maxColorValue: The maximum color value of the PPM file.
  • format: The PPM file format ("P3" or "P6").

parsePPMP3(data: Uint8Array): PPMImage

• Description: Parses PPM files in P3 format (plain text).
• Parameters:
  • data: A Uint8Array containing the PPM file's binary data.
• Returns: Same as parsePPM.

parsePPMP6(data: Uint8Array): PPMImage

• Description: Parses PPM files in P6 format (binary).
• Parameters:
  • data: A Uint8Array containing the PPM file's binary data.
• Returns: Same as parsePPM.

Extended Features

PPMImage Class

The library now provides a PPMImage class to encapsulate parsed image data. This class includes the following:

Properties:

• width: The width of the image in pixels.
• height: The height of the image in pixels.
• pixelData: The raw pixel data as a Uint8Array. Each pixel consists of three consecutive values (R, G, B).
• maxColorValue: The maximum color value of the PPM file (e.g., 255 for 8-bit color).
• format: The PPM file format ("P3" or "P6").

Methods:

• aspectRatio(): number
  • Returns the aspect ratio of the image (width / height).
• pixelCount: number
  • The total number of pixels in the image (width * height).
• getPixel(x: number, y: number): { r: number; g: number; b: number }
  • Retrieves the RGB color values of the pixel at the specified coordinates.

Development Setup

1. Clone the Repository:

   git clone https://github.com/jackashton/ppm-parser.git
   cd ppm-parser

2. Install Development Dependencies:

   pnpm install

3. Run Linting: Ensure code consistency using ESLint and Prettier:

   pnpm lint

4. Run Tests: Run unit tests using Vitest:

   pnpm test

5. Build the Project: Compile the TypeScript code:

   pnpm build

Adding a New Parser

If you want to support additional formats (e.g., a hypothetical P7 format), follow these steps:

1. Create a New Parser Function: Add a new function, e.g., parsePPMP7, in the parsePPM.ts file.

2. Update the Main Function: Modify the parsePPM function to detect and handle the new format.

3. Write Tests: Add comprehensive unit tests for the new format in the parsePPM.test.ts file.

4. Export the Function: Ensure your new parser is exported in index.ts.

Code Structure

• src/: Contains the source code for the library.
• dist/: The output directory for the built package.

Contributing

Contributions are welcome! Please fork the repository, make your changes, and submit a pull request. Ensure all code is linted and tested before submitting.

Guidelines

• Follow the existing coding style enforced by Prettier and ESLint.
• Write unit tests for all new features or bug fixes.
• Update the README if you add new features or modify existing functionality.

License

This project is licensed under the MIT License. See the LICENSE file for more details.