napi_jpeg

install requirements

apt-get install -y libjpeg-turbo8-dev

use

decode jpeg

mod = require("napi_jpeg")
fs = require("fs")

src = fs.readFileSync("test/input.jpg")
res = mod.jpeg_decode_size(src)
console.log(res)
size_x = res[0]
size_y = res[1]
dst_rgba = Buffer.alloc(4*size_x*size_y)
mod.jpeg_decode_rgba(src, dst_rgba)
dst_rgb = Buffer.alloc(3*size_x*size_y)
mod.jpeg_decode_rgb(src, dst_rgb)


// encode API is really strange (but for purpose)
// we want reuse as much buffers as possible (less allocs possible)
jpeg_dst = Buffer.alloc(4*1920*1080)
res = mod.jpeg_encode_rgba dst_rgba, size_x, size_y, jpeg_dst, target_buffer_desired_offset = 0, quality = 100
start   = res[0]
length  = res[1]
buf     = res[2]
// now we have 2 different situations
//  
//  1. encoded_length + target_buffer_desired_offset < jpeg_dst.length
//  then we can reuse buffer, so we return buf == jpeg_dst, start == target_buffer_desired_offset, length == encoded_length
//  2. not enough space to write
//  then we need allocate new buffer, buf != jpeg_dst, start == 0, length == encoded_length

// target_buffer_desired_offset is needed if we want use 1 big buffer for multiple images, so we can use space more effectively (theoretically for some applications)

// mod.jpeg_encode_rgb is also available

Thanks

inspired by zhangyuanwei/node-images