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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.
// Package image implements a basic 2-D image library.
//
// See "The Go image package" for an introduction to this package:
// http://blog.golang.org/2011/09/go-image-package.html
package image
// Config holds an image's color model and dimensions.
type Config struct {
ColorModel ColorModel
Width, Height int
}
// 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
}
// RGBA is an in-memory image of RGBAColor values.
type RGBA struct {
// Pix holds the image's pixels, in R, G, B, A order. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return RGBAColor{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
return RGBAColor{p.Pix[i+0], p.Pix[i+1], p.Pix[i+2], p.Pix[i+3]}
}
func (p *RGBA) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
c1 := toRGBAColor(c).(RGBAColor)
p.Pix[i+0] = c1.R
p.Pix[i+1] = c1.G
p.Pix[i+2] = c1.B
p.Pix[i+3] = c1.A
}
func (p *RGBA) SetRGBA(x, y int, c RGBAColor) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
p.Pix[i+0] = c.R
p.Pix[i+1] = c.G
p.Pix[i+2] = c.B
p.Pix[i+3] = c.A
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *RGBA) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &RGBA{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*4
return &RGBA{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 3, p.Rect.Dx()*4
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 4 {
if p.Pix[i] != 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([]uint8, 4*w*h)
return &RGBA{buf, 4 * w, Rectangle{ZP, Point{w, h}}}
}
// RGBA64 is an in-memory image of RGBA64Color values.
type RGBA64 struct {
// Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return RGBA64Color{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
return RGBA64Color{
uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1]),
uint16(p.Pix[i+2])<<8 | uint16(p.Pix[i+3]),
uint16(p.Pix[i+4])<<8 | uint16(p.Pix[i+5]),
uint16(p.Pix[i+6])<<8 | uint16(p.Pix[i+7]),
}
}
func (p *RGBA64) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
c1 := toRGBA64Color(c).(RGBA64Color)
p.Pix[i+0] = uint8(c1.R >> 8)
p.Pix[i+1] = uint8(c1.R)
p.Pix[i+2] = uint8(c1.G >> 8)
p.Pix[i+3] = uint8(c1.G)
p.Pix[i+4] = uint8(c1.B >> 8)
p.Pix[i+5] = uint8(c1.B)
p.Pix[i+6] = uint8(c1.A >> 8)
p.Pix[i+7] = uint8(c1.A)
}
func (p *RGBA64) SetRGBA64(x, y int, c RGBA64Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
p.Pix[i+0] = uint8(c.R >> 8)
p.Pix[i+1] = uint8(c.R)
p.Pix[i+2] = uint8(c.G >> 8)
p.Pix[i+3] = uint8(c.G)
p.Pix[i+4] = uint8(c.B >> 8)
p.Pix[i+5] = uint8(c.B)
p.Pix[i+6] = uint8(c.A >> 8)
p.Pix[i+7] = uint8(c.A)
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *RGBA64) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &RGBA64{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*8
return &RGBA64{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 6, p.Rect.Dx()*8
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 8 {
if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff {
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([]uint8, 8*w*h)
return &RGBA64{pix, 8 * w, Rectangle{ZP, Point{w, h}}}
}
// NRGBA is an in-memory image of NRGBAColor values.
type NRGBA struct {
// Pix holds the image's pixels, in R, G, B, A order. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return NRGBAColor{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
return NRGBAColor{p.Pix[i+0], p.Pix[i+1], p.Pix[i+2], p.Pix[i+3]}
}
func (p *NRGBA) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
c1 := toNRGBAColor(c).(NRGBAColor)
p.Pix[i+0] = c1.R
p.Pix[i+1] = c1.G
p.Pix[i+2] = c1.B
p.Pix[i+3] = c1.A
}
func (p *NRGBA) SetNRGBA(x, y int, c NRGBAColor) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
p.Pix[i+0] = c.R
p.Pix[i+1] = c.G
p.Pix[i+2] = c.B
p.Pix[i+3] = c.A
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *NRGBA) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &NRGBA{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*4
return &NRGBA{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 3, p.Rect.Dx()*4
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 4 {
if p.Pix[i] != 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([]uint8, 4*w*h)
return &NRGBA{pix, 4 * w, Rectangle{ZP, Point{w, h}}}
}
// NRGBA64 is an in-memory image of NRGBA64Color values.
type NRGBA64 struct {
// Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return NRGBA64Color{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
return NRGBA64Color{
uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1]),
uint16(p.Pix[i+2])<<8 | uint16(p.Pix[i+3]),
uint16(p.Pix[i+4])<<8 | uint16(p.Pix[i+5]),
uint16(p.Pix[i+6])<<8 | uint16(p.Pix[i+7]),
}
}
func (p *NRGBA64) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
c1 := toNRGBA64Color(c).(NRGBA64Color)
p.Pix[i+0] = uint8(c1.R >> 8)
p.Pix[i+1] = uint8(c1.R)
p.Pix[i+2] = uint8(c1.G >> 8)
p.Pix[i+3] = uint8(c1.G)
p.Pix[i+4] = uint8(c1.B >> 8)
p.Pix[i+5] = uint8(c1.B)
p.Pix[i+6] = uint8(c1.A >> 8)
p.Pix[i+7] = uint8(c1.A)
}
func (p *NRGBA64) SetNRGBA64(x, y int, c NRGBA64Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
p.Pix[i+0] = uint8(c.R >> 8)
p.Pix[i+1] = uint8(c.R)
p.Pix[i+2] = uint8(c.G >> 8)
p.Pix[i+3] = uint8(c.G)
p.Pix[i+4] = uint8(c.B >> 8)
p.Pix[i+5] = uint8(c.B)
p.Pix[i+6] = uint8(c.A >> 8)
p.Pix[i+7] = uint8(c.A)
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *NRGBA64) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &NRGBA64{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*8
return &NRGBA64{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 6, p.Rect.Dx()*8
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 8 {
if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff {
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([]uint8, 8*w*h)
return &NRGBA64{pix, 8 * w, Rectangle{ZP, Point{w, h}}}
}
// Alpha is an in-memory image of AlphaColor values.
type Alpha struct {
// Pix holds the image's pixels, as alpha values. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return AlphaColor{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
return AlphaColor{p.Pix[i]}
}
func (p *Alpha) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = toAlphaColor(c).(AlphaColor).A
}
func (p *Alpha) SetAlpha(x, y int, c AlphaColor) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = c.A
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *Alpha) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &Alpha{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*1
return &Alpha{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 0, p.Rect.Dx()
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i++ {
if p.Pix[i] != 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([]uint8, 1*w*h)
return &Alpha{pix, 1 * w, Rectangle{ZP, Point{w, h}}}
}
// Alpha16 is an in-memory image of Alpha16Color values.
type Alpha16 struct {
// Pix holds the image's pixels, as alpha values in big-endian format. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return Alpha16Color{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
return Alpha16Color{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])}
}
func (p *Alpha16) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
c1 := toAlpha16Color(c).(Alpha16Color)
p.Pix[i+0] = uint8(c1.A >> 8)
p.Pix[i+1] = uint8(c1.A)
}
func (p *Alpha16) SetAlpha16(x, y int, c Alpha16Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
p.Pix[i+0] = uint8(c.A >> 8)
p.Pix[i+1] = uint8(c.A)
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *Alpha16) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &Alpha16{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*2
return &Alpha16{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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
}
i0, i1 := 0, p.Rect.Dx()*2
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 2 {
if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff {
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([]uint8, 2*w*h)
return &Alpha16{pix, 2 * w, Rectangle{ZP, Point{w, h}}}
}
// Gray is an in-memory image of GrayColor values.
type Gray struct {
// Pix holds the image's pixels, as gray values. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return GrayColor{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
return GrayColor{p.Pix[i]}
}
func (p *Gray) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = toGrayColor(c).(GrayColor).Y
}
func (p *Gray) SetGray(x, y int, c GrayColor) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = c.Y
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *Gray) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &Gray{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*1
return &Gray{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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([]uint8, 1*w*h)
return &Gray{pix, 1 * w, Rectangle{ZP, Point{w, h}}}
}
// Gray16 is an in-memory image of Gray16Color values.
type Gray16 struct {
// Pix holds the image's pixels, as gray values in big-endian format. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return Gray16Color{}
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
return Gray16Color{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])}
}
func (p *Gray16) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
c1 := toGray16Color(c).(Gray16Color)
p.Pix[i+0] = uint8(c1.Y >> 8)
p.Pix[i+1] = uint8(c1.Y)
}
func (p *Gray16) SetGray16(x, y int, c Gray16Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
p.Pix[i+0] = uint8(c.Y >> 8)
p.Pix[i+1] = uint8(c.Y)
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *Gray16) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &Gray16{}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*2
return &Gray16{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// 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([]uint8, 2*w*h)
return &Gray16{pix, 2 * w, Rectangle{ZP, Point{w, h}}}
}
// A PalettedColorModel represents a fixed palette of at most 256 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
}
return p[p.Index(c)]
}
// Index returns the index of the palette color closest to c in Euclidean
// R,G,B space.
func (p PalettedColorModel) Index(c Color) int {
cr, cg, cb, _ := c.RGBA()
// Shift by 1 bit to avoid potential uint32 overflow in sum-squared-difference.
cr >>= 1
cg >>= 1
cb >>= 1
ret, bestSSD := 0, uint32(1<<32-1)
for i, 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 {
ret, bestSSD = i, ssd
}
}
return ret
}
// Paletted is an in-memory image of uint8 indices into a given palette.
type Paletted struct {
// Pix holds the image's pixels, as palette indices. The pixel at
// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
Pix []uint8
// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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 !(Point{x, y}.In(p.Rect)) {
return p.Palette[0]
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
return p.Palette[p.Pix[i]]
}
func (p *Paletted) Set(x, y int, c Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = uint8(p.Palette.Index(c))
}
func (p *Paletted) ColorIndexAt(x, y int) uint8 {
if !(Point{x, y}.In(p.Rect)) {
return 0
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
return p.Pix[i]
}
func (p *Paletted) SetColorIndex(x, y int, index uint8) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := (y-p.Rect.Min.Y)*p.Stride + (x - p.Rect.Min.X)
p.Pix[i] = index
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *Paletted) SubImage(r Rectangle) Image {
r = r.Intersect(p.Rect)
// 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 &Paletted{
Palette: p.Palette,
}
}
i := (r.Min.Y-p.Rect.Min.Y)*p.Stride + (r.Min.X-p.Rect.Min.X)*1
return &Paletted{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: p.Rect.Intersect(r),
Palette: p.Palette,
}
}
// Opaque scans the entire image and returns whether or not it is fully opaque.
func (p *Paletted) Opaque() bool {
var present [256]bool
i0, i1 := 0, p.Rect.Dx()
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for _, c := range p.Pix[i0:i1] {
present[c] = true
}
i0 += p.Stride
i1 += p.Stride
}
for i, c := range p.Palette {
if !present[i] {
continue
}
_, _, _, 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, 1*w*h)
return &Paletted{pix, 1 * w, Rectangle{ZP, Point{w, h}}, m}
}