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image.go
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image.go
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// Copyright 2015 <chaishushan{AT}gmail.com>. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package webp
import (
"image"
"image/color"
"reflect"
"runtime"
"unsafe"
)
const (
MemPMagic = "MemP" // See https://github.com/chai2010/image
)
const (
isLittleEndian = (runtime.GOARCH == "386" ||
runtime.GOARCH == "amd64" ||
runtime.GOARCH == "arm" ||
runtime.GOARCH == "arm64")
)
var (
_ image.Image = (*MemPImage)(nil)
_ MemP = (*MemPImage)(nil)
)
// MemP Image Spec (Native Endian), see https://github.com/chai2010/image.
type MemP interface {
MemPMagic() string
Bounds() image.Rectangle
Channels() int
DataType() reflect.Kind
Pix() []byte // PixSilce type
// Stride is the Pix stride (in bytes, must align with SizeofKind(p.DataType))
// between vertically adjacent pixels.
Stride() int
}
type MemPImage struct {
XMemPMagic string // MemP
XRect image.Rectangle
XChannels int
XDataType reflect.Kind
XPix PixSlice
XStride int
}
func NewMemPImage(r image.Rectangle, channels int, dataType reflect.Kind) *MemPImage {
m := &MemPImage{
XMemPMagic: MemPMagic,
XRect: r,
XStride: r.Dx() * channels * SizeofKind(dataType),
XChannels: channels,
XDataType: dataType,
}
m.XPix = make([]byte, r.Dy()*m.XStride)
return m
}
// m is MemP or image.Image
func AsMemPImage(m interface{}) (p *MemPImage, ok bool) {
if m, ok := m.(*MemPImage); ok {
return m, true
}
if m, ok := m.(MemP); ok {
return &MemPImage{
XMemPMagic: MemPMagic,
XRect: m.Bounds(),
XChannels: m.Channels(),
XDataType: m.DataType(),
XPix: m.Pix(),
XStride: m.Stride(),
}, true
}
if m, ok := m.(*image.Gray); ok {
return &MemPImage{
XMemPMagic: MemPMagic,
XRect: m.Bounds(),
XChannels: 1,
XDataType: reflect.Uint8,
XPix: m.Pix,
XStride: m.Stride,
}, true
}
if m, ok := m.(*image.RGBA); ok {
return &MemPImage{
XMemPMagic: MemPMagic,
XRect: m.Bounds(),
XChannels: 4,
XDataType: reflect.Uint8,
XPix: m.Pix,
XStride: m.Stride,
}, true
}
return nil, false
}
func NewMemPImageFrom(m image.Image) *MemPImage {
if p, ok := m.(*MemPImage); ok {
return p.Clone()
}
if p, ok := AsMemPImage(m); ok {
return p.Clone()
}
switch m := m.(type) {
case *image.Gray:
b := m.Bounds()
p := NewMemPImage(b, 1, reflect.Uint8)
for y := b.Min.Y; y < b.Max.Y; y++ {
off0 := m.PixOffset(0, y)
off1 := p.PixOffset(0, y)
copy(p.XPix[off1:][:p.XStride], m.Pix[off0:][:m.Stride])
off0 += m.Stride
off1 += p.XStride
}
return p
case *image.Gray16:
b := m.Bounds()
p := NewMemPImage(b, 1, reflect.Uint16)
for y := b.Min.Y; y < b.Max.Y; y++ {
off0 := m.PixOffset(0, y)
off1 := p.PixOffset(0, y)
copy(p.XPix[off1:][:p.XStride], m.Pix[off0:][:m.Stride])
off0 += m.Stride
off1 += p.XStride
}
if isLittleEndian {
p.XPix.SwapEndian(p.XDataType)
}
return p
case *image.RGBA:
b := m.Bounds()
p := NewMemPImage(b, 4, reflect.Uint8)
for y := b.Min.Y; y < b.Max.Y; y++ {
off0 := m.PixOffset(0, y)
off1 := p.PixOffset(0, y)
copy(p.XPix[off1:][:p.XStride], m.Pix[off0:][:m.Stride])
off0 += m.Stride
off1 += p.XStride
}
return p
case *image.RGBA64:
b := m.Bounds()
p := NewMemPImage(b, 4, reflect.Uint16)
for y := b.Min.Y; y < b.Max.Y; y++ {
off0 := m.PixOffset(0, y)
off1 := p.PixOffset(0, y)
copy(p.XPix[off1:][:p.XStride], m.Pix[off0:][:m.Stride])
off0 += m.Stride
off1 += p.XStride
}
if isLittleEndian {
p.XPix.SwapEndian(p.XDataType)
}
return p
case *image.YCbCr:
b := m.Bounds()
p := NewMemPImage(b, 4, reflect.Uint8)
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
R, G, B, A := m.At(x, y).RGBA()
i := p.PixOffset(x, y)
p.XPix[i+0] = uint8(R >> 8)
p.XPix[i+1] = uint8(G >> 8)
p.XPix[i+2] = uint8(B >> 8)
p.XPix[i+3] = uint8(A >> 8)
}
}
return p
default:
b := m.Bounds()
p := NewMemPImage(b, 4, reflect.Uint16)
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
R, G, B, A := m.At(x, y).RGBA()
i := p.PixOffset(x, y)
p.XPix[i+0] = uint8(R >> 8)
p.XPix[i+1] = uint8(R)
p.XPix[i+2] = uint8(G >> 8)
p.XPix[i+3] = uint8(G)
p.XPix[i+4] = uint8(B >> 8)
p.XPix[i+5] = uint8(B)
p.XPix[i+6] = uint8(A >> 8)
p.XPix[i+7] = uint8(A)
}
}
return p
}
}
func (p *MemPImage) Clone() *MemPImage {
q := new(MemPImage)
*q = *p
q.XPix = append([]byte(nil), p.XPix...)
return q
}
func (p *MemPImage) MemPMagic() string {
return p.XMemPMagic
}
func (p *MemPImage) Bounds() image.Rectangle {
return p.XRect
}
func (p *MemPImage) Channels() int {
return p.XChannels
}
func (p *MemPImage) DataType() reflect.Kind {
return p.XDataType
}
func (p *MemPImage) Pix() []byte {
return p.XPix
}
func (p *MemPImage) Stride() int {
return p.XStride
}
func (p *MemPImage) ColorModel() color.Model {
return ColorModel(p.XChannels, p.XDataType)
}
func (p *MemPImage) At(x, y int) color.Color {
if !(image.Point{x, y}.In(p.XRect)) {
return MemPColor{
Channels: p.XChannels,
DataType: p.XDataType,
}
}
i := p.PixOffset(x, y)
n := SizeofPixel(p.XChannels, p.XDataType)
return MemPColor{
Channels: p.XChannels,
DataType: p.XDataType,
Pix: p.XPix[i:][:n],
}
}
func (p *MemPImage) PixelAt(x, y int) []byte {
if !(image.Point{x, y}.In(p.XRect)) {
return nil
}
i := p.PixOffset(x, y)
n := SizeofPixel(p.XChannels, p.XDataType)
return p.XPix[i:][:n]
}
func (p *MemPImage) Set(x, y int, c color.Color) {
if !(image.Point{x, y}.In(p.XRect)) {
return
}
i := p.PixOffset(x, y)
n := SizeofPixel(p.XChannels, p.XDataType)
v := p.ColorModel().Convert(c).(MemPColor)
copy(p.XPix[i:][:n], v.Pix)
}
func (p *MemPImage) SetPixel(x, y int, c []byte) {
if !(image.Point{x, y}.In(p.XRect)) {
return
}
i := p.PixOffset(x, y)
n := SizeofPixel(p.XChannels, p.XDataType)
copy(p.XPix[i:][:n], c)
}
func (p *MemPImage) PixOffset(x, y int) int {
return (y-p.XRect.Min.Y)*p.XStride + (x-p.XRect.Min.X)*SizeofPixel(p.XChannels, p.XDataType)
}
func (p *MemPImage) SubImage(r image.Rectangle) image.Image {
r = r.Intersect(p.XRect)
// If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside
// either r1 or r2 if the intersection is empty. Without explicitly checking for
// this, the Pix[i:] expression below can panic.
if r.Empty() {
return &MemPImage{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &MemPImage{
XRect: r,
XChannels: p.XChannels,
XDataType: p.XDataType,
XPix: p.XPix[i:],
XStride: p.XStride,
}
}
func (p *MemPImage) AsStdImage() (m image.Image, ok bool) {
switch {
case p.XChannels == 1 && p.XDataType == reflect.Uint8:
return &image.Gray{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}, true
case p.XChannels == 4 && p.XDataType == reflect.Uint8:
return &image.RGBA{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}, true
default:
return nil, false
}
}
func (p *MemPImage) StdImage() image.Image {
switch {
case p.XChannels == 1 && p.XDataType == reflect.Uint8:
return &image.Gray{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}
case p.XChannels == 1 && p.XDataType == reflect.Uint16:
m := &image.Gray16{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}
if isLittleEndian {
m.Pix = append([]byte(nil), m.Pix...)
PixSlice(m.Pix).SwapEndian(p.XDataType)
}
return m
case p.XChannels == 4 && p.XDataType == reflect.Uint8:
return &image.RGBA{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}
case p.XChannels == 4 && p.XDataType == reflect.Uint16:
m := &image.RGBA64{
Pix: p.XPix,
Stride: p.XStride,
Rect: p.XRect,
}
if isLittleEndian {
m.Pix = append([]byte(nil), m.Pix...)
PixSlice(m.Pix).SwapEndian(p.XDataType)
}
return m
}
return p
}
func ChannelsOf(m image.Image) int {
if m, ok := AsMemPImage(m); ok {
return m.XChannels
}
switch m.(type) {
case *image.Gray:
return 1
case *image.Gray16:
return 1
case *image.YCbCr:
return 3
}
return 4
}
func DepthOf(m image.Image) int {
if m, ok := m.(*MemPImage); ok {
return SizeofKind(m.XDataType) * 8
}
if m, ok := m.(MemP); ok {
return SizeofKind(m.DataType() * 8)
}
switch m.(type) {
case *image.Gray:
return 1 * 8
case *image.Gray16:
return 2 * 8
case *image.NRGBA:
return 1 * 8
case *image.NRGBA64:
return 2 * 8
case *image.RGBA:
return 1 * 8
case *image.RGBA64:
return 2 * 8
case *image.YCbCr:
return 1 * 8
}
return 2 * 8
}
type SizeofImager interface {
SizeofImage() int
}
func SizeofImage(m image.Image) int {
if m, ok := m.(SizeofImager); ok {
return m.SizeofImage()
}
if m, ok := AsMemPImage(m); ok {
return int(unsafe.Sizeof(*m)) + len(m.XPix)
}
b := m.Bounds()
switch m := m.(type) {
case *image.Alpha:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*1
case *image.Alpha16:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*2
case *image.Gray:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*1
case *image.Gray16:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*2
case *image.NRGBA:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*4
case *image.NRGBA64:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*8
case *image.RGBA:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*4
case *image.RGBA64:
return int(unsafe.Sizeof(*m)) + b.Dx()*b.Dy()*8
case *image.Uniform:
return int(unsafe.Sizeof(*m))
case *image.YCbCr:
return int(unsafe.Sizeof(*m)) + len(m.Y) + len(m.Cb) + len(m.Cr)
}
// return same as RGBA64 size
return int(unsafe.Sizeof((*image.RGBA64)(nil))) + b.Dx()*b.Dy()*8
}