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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// The image package implements a basic 2-D image library.
package image
// A Config consists of an image's color model and dimensions.
type Config struct {
ColorModel ColorModel
Width, Height int
}
// An Image is a finite rectangular grid of Colors drawn from a ColorModel.
type Image interface {
// ColorModel returns the Image's ColorModel.
ColorModel() ColorModel
// Bounds returns the domain for which At can return non-zero color.
// The bounds do not necessarily contain the point (0, 0).
Bounds() Rectangle
// At returns the color of the pixel at (x, y).
// At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
// At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.
At(x, y int) Color
}
// An RGBA is an in-memory image of RGBAColor values.
type RGBA struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []RGBAColor
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *RGBA) ColorModel() ColorModel { return RGBAColorModel }
func (p *RGBA) Bounds() Rectangle { return p.Rect }
func (p *RGBA) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return RGBAColor{}
}
return p.Pix[y*p.Stride+x]
}
func (p *RGBA) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toRGBAColor(c).(RGBAColor)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *RGBA) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewRGBA returns a new RGBA with the given width and height.
func NewRGBA(w, h int) *RGBA {
buf := make([]RGBAColor, w*h)
return &RGBA{buf, w, Rectangle{ZP, Point{w, h}}}
}
// An RGBA64 is an in-memory image of RGBA64Color values.
type RGBA64 struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []RGBA64Color
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *RGBA64) ColorModel() ColorModel { return RGBA64ColorModel }
func (p *RGBA64) Bounds() Rectangle { return p.Rect }
func (p *RGBA64) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return RGBA64Color{}
}
return p.Pix[y*p.Stride+x]
}
func (p *RGBA64) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toRGBA64Color(c).(RGBA64Color)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *RGBA64) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xffff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewRGBA64 returns a new RGBA64 with the given width and height.
func NewRGBA64(w, h int) *RGBA64 {
pix := make([]RGBA64Color, w*h)
return &RGBA64{pix, w, Rectangle{ZP, Point{w, h}}}
}
// An NRGBA is an in-memory image of NRGBAColor values.
type NRGBA struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []NRGBAColor
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *NRGBA) ColorModel() ColorModel { return NRGBAColorModel }
func (p *NRGBA) Bounds() Rectangle { return p.Rect }
func (p *NRGBA) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return NRGBAColor{}
}
return p.Pix[y*p.Stride+x]
}
func (p *NRGBA) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toNRGBAColor(c).(NRGBAColor)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *NRGBA) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewNRGBA returns a new NRGBA with the given width and height.
func NewNRGBA(w, h int) *NRGBA {
pix := make([]NRGBAColor, w*h)
return &NRGBA{pix, w, Rectangle{ZP, Point{w, h}}}
}
// An NRGBA64 is an in-memory image of NRGBA64Color values.
type NRGBA64 struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []NRGBA64Color
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *NRGBA64) ColorModel() ColorModel { return NRGBA64ColorModel }
func (p *NRGBA64) Bounds() Rectangle { return p.Rect }
func (p *NRGBA64) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return NRGBA64Color{}
}
return p.Pix[y*p.Stride+x]
}
func (p *NRGBA64) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toNRGBA64Color(c).(NRGBA64Color)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *NRGBA64) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xffff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewNRGBA64 returns a new NRGBA64 with the given width and height.
func NewNRGBA64(w, h int) *NRGBA64 {
pix := make([]NRGBA64Color, w*h)
return &NRGBA64{pix, w, Rectangle{ZP, Point{w, h}}}
}
// An Alpha is an in-memory image of AlphaColor values.
type Alpha struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []AlphaColor
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *Alpha) ColorModel() ColorModel { return AlphaColorModel }
func (p *Alpha) Bounds() Rectangle { return p.Rect }
func (p *Alpha) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return AlphaColor{}
}
return p.Pix[y*p.Stride+x]
}
func (p *Alpha) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toAlphaColor(c).(AlphaColor)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Alpha) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewAlpha returns a new Alpha with the given width and height.
func NewAlpha(w, h int) *Alpha {
pix := make([]AlphaColor, w*h)
return &Alpha{pix, w, Rectangle{ZP, Point{w, h}}}
}
// An Alpha16 is an in-memory image of Alpha16Color values.
type Alpha16 struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []Alpha16Color
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *Alpha16) ColorModel() ColorModel { return Alpha16ColorModel }
func (p *Alpha16) Bounds() Rectangle { return p.Rect }
func (p *Alpha16) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return Alpha16Color{}
}
return p.Pix[y*p.Stride+x]
}
func (p *Alpha16) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toAlpha16Color(c).(Alpha16Color)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Alpha16) Opaque() bool {
if p.Rect.Empty() {
return true
}
base := p.Rect.Min.Y * p.Stride
i0, i1 := base+p.Rect.Min.X, base+p.Rect.Max.X
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
if c.A != 0xffff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// NewAlpha16 returns a new Alpha16 with the given width and height.
func NewAlpha16(w, h int) *Alpha16 {
pix := make([]Alpha16Color, w*h)
return &Alpha16{pix, w, Rectangle{ZP, Point{w, h}}}
}
// A Gray is an in-memory image of GrayColor values.
type Gray struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []GrayColor
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *Gray) ColorModel() ColorModel { return GrayColorModel }
func (p *Gray) Bounds() Rectangle { return p.Rect }
func (p *Gray) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return GrayColor{}
}
return p.Pix[y*p.Stride+x]
}
func (p *Gray) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toGrayColor(c).(GrayColor)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Gray) Opaque() bool {
return true
}
// NewGray returns a new Gray with the given width and height.
func NewGray(w, h int) *Gray {
pix := make([]GrayColor, w*h)
return &Gray{pix, w, Rectangle{ZP, Point{w, h}}}
}
// A Gray16 is an in-memory image of Gray16Color values.
type Gray16 struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []Gray16Color
Stride int
// Rect is the image's bounds.
Rect Rectangle
}
func (p *Gray16) ColorModel() ColorModel { return Gray16ColorModel }
func (p *Gray16) Bounds() Rectangle { return p.Rect }
func (p *Gray16) At(x, y int) Color {
if !p.Rect.Contains(Point{x, y}) {
return Gray16Color{}
}
return p.Pix[y*p.Stride+x]
}
func (p *Gray16) Set(x, y int, c Color) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = toGray16Color(c).(Gray16Color)
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Gray16) Opaque() bool {
return true
}
// NewGray16 returns a new Gray16 with the given width and height.
func NewGray16(w, h int) *Gray16 {
pix := make([]Gray16Color, w*h)
return &Gray16{pix, w, Rectangle{ZP, Point{w, h}}}
}
// A PalettedColorModel represents a fixed palette of colors.
type PalettedColorModel []Color
func diff(a, b uint32) uint32 {
if a > b {
return a - b
}
return b - a
}
// Convert returns the palette color closest to c in Euclidean R,G,B space.
func (p PalettedColorModel) Convert(c Color) Color {
if len(p) == 0 {
return nil
}
cr, cg, cb, _ := c.RGBA()
// Shift by 1 bit to avoid potential uint32 overflow in sum-squared-difference.
cr >>= 1
cg >>= 1
cb >>= 1
result := Color(nil)
bestSSD := uint32(1<<32 - 1)
for _, v := range p {
vr, vg, vb, _ := v.RGBA()
vr >>= 1
vg >>= 1
vb >>= 1
dr, dg, db := diff(cr, vr), diff(cg, vg), diff(cb, vb)
ssd := (dr * dr) + (dg * dg) + (db * db)
if ssd < bestSSD {
bestSSD = ssd
result = v
}
}
return result
}
// A Paletted is an in-memory image backed by a 2-D slice of uint8 values and a PalettedColorModel.
type Paletted struct {
// Pix holds the image's pixels. The pixel at (x, y) is Pix[y*Stride+x].
Pix []uint8
Stride int
// Rect is the image's bounds.
Rect Rectangle
// Palette is the image's palette.
Palette PalettedColorModel
}
func (p *Paletted) ColorModel() ColorModel { return p.Palette }
func (p *Paletted) Bounds() Rectangle { return p.Rect }
func (p *Paletted) At(x, y int) Color {
if len(p.Palette) == 0 {
return nil
}
if !p.Rect.Contains(Point{x, y}) {
return p.Palette[0]
}
return p.Palette[p.Pix[y*p.Stride+x]]
}
func (p *Paletted) ColorIndexAt(x, y int) uint8 {
if !p.Rect.Contains(Point{x, y}) {
return 0
}
return p.Pix[y*p.Stride+x]
}
func (p *Paletted) SetColorIndex(x, y int, index uint8) {
if !p.Rect.Contains(Point{x, y}) {
return
}
p.Pix[y*p.Stride+x] = index
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Paletted) Opaque() bool {
for _, c := range p.Palette {
_, _, _, a := c.RGBA()
if a != 0xffff {
return false
}
}
return true
}
// NewPaletted returns a new Paletted with the given width, height and palette.
func NewPaletted(w, h int, m PalettedColorModel) *Paletted {
pix := make([]uint8, w*h)
return &Paletted{pix, w, Rectangle{ZP, Point{w, h}}, m}
}