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rgb.go
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rgb.go
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// Copyright 2021 The Embedded 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 images
import (
"image"
"image/color"
)
var (
RGBModel = color.ModelFunc(rgbModel)
RGB16Model = color.ModelFunc(rgb16Model)
)
func rgbModel(c color.Color) color.Color {
if c, ok := c.(color.RGBA); ok {
c.A = 255
return c
}
r, g, b, _ := c.RGBA()
return color.RGBA{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), 255}
}
func rgb16Model(c color.Color) color.Color {
var r, g, b uint32
if c, ok := c.(color.RGBA); ok {
r = uint32(c.R)
g = uint32(c.G)
b = uint32(c.B)
} else {
r, g, b, _ = c.RGBA()
r >>= 8
g >>= 8
b >>= 8
}
return color.RGBA{
uint8(r&^7 | r>>5),
uint8(g&^3 | g>>6),
uint8(b&^7 | b>>5),
255,
}
}
func rgb16torgba(h, l uint8) color.RGBA {
r := h &^ 7
g := (h<<5 | l>>3) &^ 3
b := l << 3
return color.RGBA{
r | r>>5,
g | g>>6,
b | b>>5,
255,
}
}
func rgb16torgba64(h, l uint8) color.RGBA64 {
r := uint(h&^7) << 8
g := (uint(h)<<13 | uint(l)<<5) & 0xfc00
b := (uint(l) << 11) & 0xf800
return color.RGBA64{
uint16(r | r>>5 | r>>10 | r>>15),
uint16(g | g>>6 | g>>12),
uint16(b | b>>5 | b>>10 | b>>15),
0xffff,
}
}
// RGB is an in-memory image whose At method returns RGB values.
type RGB struct {
Rect image.Rectangle // image bounds
Stride int // stride (in bytes) between vertically adjacent pixels
Pix []uint8 // the image pixels
}
// NewRGB returns a new RGB image with the given bounds.
func NewRGB(r image.Rectangle) *RGB {
return &RGB{
Rect: r,
Stride: 3 * r.Dx(),
Pix: make([]uint8, 3*r.Dx()*r.Dy()),
}
}
func (p *RGB) ColorModel() color.Model { return RGBModel }
func (p *RGB) Bounds() image.Rectangle { return p.Rect }
func (p *RGB) Opaque() bool { return true }
func (p *RGB) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *RGB) RGBAAt(x, y int) color.RGBA {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
return color.RGBA{s[0], s[1], s[2], 255}
}
func (p *RGB) RGBA64At(x, y int) color.RGBA64 {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
r := uint16(s[0])
g := uint16(s[1])
b := uint16(s[2])
return color.RGBA64{r | r<<8, g | g<<8, b | b<<8, 255}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *RGB) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*3
}
func (p *RGB) Set(x, y int, c color.Color) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := RGBModel.Convert(c).(color.RGBA)
s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c1.R
s[1] = c1.G
s[2] = c1.B
}
func (p *RGB) SetRGBA(x, y int, c color.RGBA) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c.R
s[1] = c.G
s[2] = c.B
}
func (p *RGB) SetRGBA64(x, y int, c color.RGBA64) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(c.R >> 8)
s[1] = uint8(c.G >> 8)
s[2] = uint8(c.B >> 8)
}
// 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 *RGB) SubImage(r image.Rectangle) image.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 &RGB{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &RGB{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// ImmRGB is an immutable counterpart of RGB.
type ImmRGB struct {
Rect image.Rectangle // image bounds
Stride int // stride (in bytes) between vertically adjacent pixels
Pix string // the image pixels
}
// NewImmRGB returns a new ImmRGB image with the given bounds and content
func NewImmRGB(r image.Rectangle, bits string) *ImmRGB {
return &ImmRGB{
Rect: r,
Stride: 3 * r.Dx(),
Pix: bits,
}
}
func (p *ImmRGB) ColorModel() color.Model { return RGBModel }
func (p *ImmRGB) Bounds() image.Rectangle { return p.Rect }
func (p *ImmRGB) Opaque() bool { return true }
func (p *ImmRGB) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *ImmRGB) RGBAAt(x, y int) color.RGBA {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3] // Small cap improves performance, see https://golang.org/issue/27857
return color.RGBA{s[0], s[1], s[2], 255}
}
func (p *ImmRGB) RGBA64At(x, y int) color.RGBA64 {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+3] // Small cap improves performance, see https://golang.org/issue/27857
r := uint16(s[0])
g := uint16(s[1])
b := uint16(s[2])
return color.RGBA64{r | r<<8, g | g<<8, b | b<<8, 255}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *ImmRGB) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*3
}
// 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 *ImmRGB) SubImage(r image.Rectangle) image.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 &ImmRGB{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &ImmRGB{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// RGB16 is an in-memory image whose At method returns RGB16 values.
type RGB16 struct {
Rect image.Rectangle // image bounds
Stride int // stride (in bytes) between vertically adjacent pixels
Pix []uint8 // the image pixels
}
// NewRGB16 returns a new RGB16 image with the given bounds.
func NewRGB16(r image.Rectangle) *RGB16 {
return &RGB16{
Rect: r,
Stride: 2 * r.Dx(),
Pix: make([]uint8, 2*r.Dx()*r.Dy()),
}
}
func (p *RGB16) ColorModel() color.Model { return RGB16Model }
func (p *RGB16) Bounds() image.Rectangle { return p.Rect }
func (p *RGB16) Opaque() bool { return true }
func (p *RGB16) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *RGB16) RGBAAt(x, y int) color.RGBA {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2 : i+2] // Small cap improves performance, see https://golang.org/issue/27857
return rgb16torgba(s[0], s[1])
}
func (p *RGB16) RGBA64At(x, y int) color.RGBA64 {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2 : i+2] // Small cap improves performance, see https://golang.org/issue/27857
return rgb16torgba64(s[0], s[1])
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *RGB16) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
}
func (p *RGB16) Set(x, y int, c color.Color) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
var r, g, b uint32
if c, ok := c.(color.RGBA); ok {
r = uint32(c.R)
g = uint32(c.G)
b = uint32(c.B)
} else {
r, g, b, _ = c.RGBA()
r >>= 8
g >>= 8
b >>= 8
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2 : i+2] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(r&^7 | g>>5)
s[1] = uint8((g&^3)<<3 | b>>3)
}
func (p *RGB16) SetRGBA(x, y int, c color.RGBA) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2 : i+2] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c.R&^7 | c.G>>5
s[1] = (c.G&^3)<<3 | c.B>>3
}
func (p *RGB16) SetRGBA64(x, y int, c color.RGBA64) {
if !(image.Pt(x, y).In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2 : i+2] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8((c.R>>8)&^7 | c.G>>13)
s[1] = uint8((c.G&0xfc00)>>5 | c.B>>11)
}
// 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 *RGB16) SubImage(r image.Rectangle) image.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 &RGB16{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &RGB{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// ImmRGB16 is an immutable counterpart of RGB16.
type ImmRGB16 struct {
Rect image.Rectangle // image bounds
Stride int // stride (in bytes) between vertically adjacent pixels
Pix string // the image pixels
}
// NewImmRGB16 returns a new ImmRGB16 image with the given bounds and content.
func NewImmRGB16(r image.Rectangle, bits string) *ImmRGB16 {
return &ImmRGB16{
Rect: r,
Stride: 2 * r.Dx(),
Pix: bits,
}
}
func (p *ImmRGB16) ColorModel() color.Model { return RGB16Model }
func (p *ImmRGB16) Bounds() image.Rectangle { return p.Rect }
func (p *ImmRGB16) Opaque() bool { return true }
func (p *ImmRGB16) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *ImmRGB16) RGBAAt(x, y int) color.RGBA {
if !(image.Pt(x, y).In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+2]
return rgb16torgba(s[0], s[1])
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *ImmRGB16) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
}
// 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 *ImmRGB16) SubImage(r image.Rectangle) image.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 &ImmRGB16{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &ImmRGB16{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}