turbo

README

Turbo (TurboJPEG Go wrapper)

This is a very thin wrapper around turbojpeg.

Why not use https://github.com/pixiv/go-libjpeg ?

Because go-libjpeg is built to use the libjpeg-compatible API of either libjpeg or libjpeg-turbo. That API does not allow one to specify the chroma sub-sampling, so you're unable to compress to 4:2:0. That was the sole reason for building this package -- to enable compression to 420 chroma sub-sampling.

This wrapper links explicitly to TurboJPEG. There is no fallback to libjpeg.

How to use

import "github.com/bmharper/turbo"

func compressImage(width, height int, rgba []byte) {
	raw := turbo.Image{
		Width: width,
		Height: height,
		Stride: width * 4,
		RGBA: rgba,
	}
	params := turbo.MakeCompressParams(turbo.PixelFormatRGBA, turbo.Sampling420, 35, 0)
	jpg, err := turbo.Compress(&raw, params)
}

func decompressImage(jpg []byte) (*Image, error) {
	return turbo.Decompress(jpg)
}

Documentation

Index

• func Compress(img *Image, params CompressParams) ([]byte, error)
• type CompressParams
  • func MakeCompressParams(pixelFormat PixelFormat, sampling Sampling, quality int, flags Flags) CompressParams
• type Flags
• type Image
  • func Decompress(encoded []byte) (*Image, error)
  • func FromImage(src image.Image, allowDeepClone bool) *Image
• type PixelFormat
• type Sampling

Functions

func Compress

func Compress(img *Image, params CompressParams) ([]byte, error)

Types

type CompressParams

type CompressParams struct {
	PixelFormat PixelFormat
	Sampling    Sampling
	Quality     int // 1 .. 100
	Flags       Flags
}

func MakeCompressParams

func MakeCompressParams(pixelFormat PixelFormat, sampling Sampling, quality int, flags Flags) CompressParams

type Flags

type Flags C.int

const (
	FlagAccurateDCT   Flags = C.TJFLAG_ACCURATEDCT
	FlagBottomUp      Flags = C.TJFLAG_BOTTOMUP
	FlagFastDCT       Flags = C.TJFLAG_FASTDCT
	FlagFastUpsample  Flags = C.TJFLAG_FASTUPSAMPLE
	FlagNoRealloc     Flags = C.TJFLAG_NOREALLOC
	FlagProgressive   Flags = C.TJFLAG_PROGRESSIVE
	FlagStopOnWarning Flags = C.TJFLAG_STOPONWARNING
)

type Image

type Image struct {
	Width  int
	Height int
	Stride int
	Pixels []byte
}

func Decompress

func Decompress(encoded []byte) (*Image, error)

func FromImage

func FromImage(src image.Image, allowDeepClone bool) *Image

Convert a Go image.Image into a turbo.Image If allowDeepClone is true, and the source image is type NRGBA or RGBA, then the resulting Image points directly to the pixel buffer of the source image.

type PixelFormat

type PixelFormat C.int

const (
	PixelFormatRGB     PixelFormat = C.TJPF_RGB
	PixelFormatBGR     PixelFormat = C.TJPF_BGR
	PixelFormatRGBX    PixelFormat = C.TJPF_RGBX
	PixelFormatBGRX    PixelFormat = C.TJPF_BGRX
	PixelFormatXBGR    PixelFormat = C.TJPF_XBGR
	PixelFormatXRGB    PixelFormat = C.TJPF_XRGB
	PixelFormatGRAY    PixelFormat = C.TJPF_GRAY
	PixelFormatRGBA    PixelFormat = C.TJPF_RGBA
	PixelFormatBGRA    PixelFormat = C.TJPF_BGRA
	PixelFormatABGR    PixelFormat = C.TJPF_ABGR
	PixelFormatARGB    PixelFormat = C.TJPF_ARGB
	PixelFormatCMYK    PixelFormat = C.TJPF_CMYK
	PixelFormatUNKNOWN PixelFormat = C.TJPF_UNKNOWN
)

type Sampling

type Sampling C.int

const (
	Sampling444  Sampling = C.TJSAMP_444
	Sampling422  Sampling = C.TJSAMP_422
	Sampling420  Sampling = C.TJSAMP_420
	SamplingGray Sampling = C.TJSAMP_GRAY
)