node-lightnpng

Converts a Buffer to PNG format -- very, very quickly.

It's pronounced: "lightn--PING!". As in, PING! Your PNG is ready before you can say lightning.

Usage

First, install it in your project: npm install --save node-lightnpng

Then use it.

'use strict'

// For this example, we'll build an ARGB Buffer with node-canvas:
// https://github.com/Automattic/node-canvas
const Canvas = require('canvas')
const canvas = new Canvas(640, 480)
const ctx = canvas.getContext('2d')

ctx.fillStyle = 'red'
ctx.fillRect(10, 10, 200, 340)
ctx.fillStyle = 'green'
ctx.fillRect(50, 50, 30, 400);

const cairoBuf = canvas.toBuffer('raw') // ARGB, native-endian data

// Now's where this library comes in: let's create a PNG!
const lightnpng = require('node-lightnpng')
var png = lightnpng.native_argb32_to_png(
  cairoBuf,
  640,          // width (in px)
  480,          // height (in px)
  canvas.stride // number of bytes per row of image
)

Design philosophy

We start with zero features.

Features that don't inhibit speed are great.

For features that do slow things down, apply the rule: a 5 percent slowdown should make this library useful to three times as many people as already use it.

Options

Basically, we allow no options at all ... except:

• Custom width, height and row stride
• Input conversion from ARGB32 to RGB24 by dropping the alpha channel

stride

Some drawing libraries may align their arrays to machine word boundaries. The stride option specifies how many bytes are in each row.

LICENSE

BSD-style 2-clause license