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API Reference ​

Welcome to the PNGX API Reference. This section provides detailed documentation for all public APIs in the PNGX library.

Core Classes ​

  • PNG Class - The main class for PNG image processing
  • PNGSync Class - Synchronous version of the PNG class
  • Parser - PNG file parsing utilities
  • Packer - PNG file packing utilities

Quick Start ​

typescript
import { PNG } from 'pngx'

// Create a new PNG image
const png = new PNG({
  width: 100,
  height: 100
})

// Read a PNG file
png.parse(fs.readFileSync('image.png'), (err, data) => {
  if (err)
    throw err

  // Process the image
  for (let i = 0; i < data.length; i += 4) {
    // Access RGBA values
    const r = data[i]
    const g = data[i + 1]
    const b = data[i + 2]
    const a = data[i + 3]
  }

  // Write the image
  png.pack().pipe(fs.createWriteStream('output.png'))
})

Common Operations ​

Creating Images ​

typescript
// Create a blank image
const png = new PNG({
  width: 100,
  height: 100
})

// Create with specific color
const png = new PNG({
  width: 100,
  height: 100,
  colorType: 6, // RGBA
  inputColorType: 6,
  inputHasAlpha: true
})

Reading Images ​

typescript
// Asynchronous
png.parse(buffer, (err, data) => {
  if (err)
    throw err
  // Process data
})

// Synchronous
const data = pngSync.parse(buffer)

Writing Images ​

typescript
// Asynchronous
png.pack().pipe(fs.createWriteStream('output.png'))

// Synchronous
fs.writeFileSync('output.png', pngSync.pack())

Events ​

The PNG class is an EventEmitter that emits the following events:

  • metadata - Emitted when image metadata is parsed
  • gamma - Emitted when gamma value is found
  • parsed - Emitted when image is fully parsed
  • error - Emitted when an error occurs

Constants ​

Color Types ​

  • COLOR_GRAYSCALE = 0
  • COLOR_RGB = 2
  • COLOR_PALETTE = 3
  • COLOR_GRAYSCALE_ALPHA = 4
  • COLOR_RGBA = 6

Filter Types ​

  • FILTER_NONE = 0
  • FILTER_SUB = 1
  • FILTER_UP = 2
  • FILTER_AVG = 3
  • FILTER_PAETH = 4

Type Definitions ​

typescript
interface PNGMetadata {
  width: number
  height: number
  depth: number
  colorType: number
  interlace: boolean
  palette: boolean
  hasAlpha: boolean
  colorSpace: string
}

interface PNGOptions {
  width?: number
  height?: number
  fill?: boolean
  colorType?: number
  inputColorType?: number
  inputHasAlpha?: boolean
  skipRescale?: boolean
  deflateLevel?: number
  deflateStrategy?: number
  filterType?: number | number[]
  colorSpace?: string
  inputColorSpace?: string
  bgColor?: object
}

Error Handling ​

The library uses Node.js style error handling with callbacks:

typescript
png.parse(buffer, (err, data) => {
  if (err) {
    console.error('Error parsing PNG:', err)
  }
  // Process data
})

Next Steps ​