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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.
//
// The fundamental interface is called Image. An Image contains colors, which
// are described in the image/color package.
//
// Values of the Image interface are created either by calling functions such
// as NewRGBA and NewPaletted, or by calling Decode on an io.Reader containing
// image data in a format such as GIF, JPEG or PNG. Decoding any particular
// image format requires the prior registration of a decoder function.
// Registration is typically automatic as a side effect of initializing that
// format's package so that, to decode a PNG image, it suffices to have
//
// import _ "image/png"
//
// in a program's main package. The _ means to import a package purely for its
// initialization side effects.
//
// See "The Go image package" for more details:
// https://golang.org/doc/articles/image_package.html
package image
import (
"image/color"
)
// Config holds an image's color model and dimensions.
type Config struct {
ColorModel color.Model
Width, Height int
}
// Image is a finite rectangular grid of color.Color values taken from a color
// model.
type Image interface {
// ColorModel returns the Image's color model.
ColorModel() color.Model
// 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.Color
}
// RGBA64Image is an Image whose pixels can be converted directly to a
// color.RGBA64.
type RGBA64Image interface {
// RGBA64At returns the RGBA64 color of the pixel at (x, y). It is
// equivalent to calling At(x, y).RGBA() and converting the resulting
// 32-bit return values to a color.RGBA64, but it can avoid allocations
// from converting concrete color types to the color.Color interface type.
RGBA64At(x, y int) color.RGBA64
Image
}
// PalettedImage is an image whose colors may come from a limited palette.
// If m is a PalettedImage and m.ColorModel() returns a color.Palette p,
// then m.At(x, y) should be equivalent to p[m.ColorIndexAt(x, y)]. If m's
// color model is not a color.Palette, then ColorIndexAt's behavior is
// undefined.
type PalettedImage interface {
// ColorIndexAt returns the palette index of the pixel at (x, y).
ColorIndexAt(x, y int) uint8
Image
}
// pixelBufferLength returns the length of the []uint8 typed Pix slice field
// for the NewXxx functions. Conceptually, this is just (bpp * width * height),
// but this function panics if at least one of those is negative or if the
// computation would overflow the int type.
//
// This panics instead of returning an error because of backwards
// compatibility. The NewXxx functions do not return an error.
func pixelBufferLength(bytesPerPixel int, r Rectangle, imageTypeName string) int {
totalLength := mul3NonNeg(bytesPerPixel, r.Dx(), r.Dy())
if totalLength < 0 {
panic("image: New" + imageTypeName + " Rectangle has huge or negative dimensions")
}
return totalLength
}
// RGBA is an in-memory image whose At method returns color.RGBA 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() color.Model { return color.RGBAModel }
func (p *RGBA) Bounds() Rectangle { return p.Rect }
func (p *RGBA) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *RGBA) RGBA64At(x, y int) color.RGBA64 {
if !(Point{x, y}.In(p.Rect)) {
return color.RGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
r := uint16(s[0])
g := uint16(s[1])
b := uint16(s[2])
a := uint16(s[3])
return color.RGBA64{
(r << 8) | r,
(g << 8) | g,
(b << 8) | b,
(a << 8) | a,
}
}
func (p *RGBA) RGBAAt(x, y int) color.RGBA {
if !(Point{x, y}.In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
return color.RGBA{s[0], s[1], s[2], s[3]}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *RGBA) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
}
func (p *RGBA) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.RGBAModel.Convert(c).(color.RGBA)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c1.R
s[1] = c1.G
s[2] = c1.B
s[3] = c1.A
}
func (p *RGBA) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // 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)
s[3] = uint8(c.A >> 8)
}
func (p *RGBA) SetRGBA(x, y int, c color.RGBA) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c.R
s[1] = c.G
s[2] = c.B
s[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 := p.PixOffset(r.Min.X, r.Min.Y)
return &RGBA{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewRGBA(r Rectangle) *RGBA {
return &RGBA{
Pix: make([]uint8, pixelBufferLength(4, r, "RGBA")),
Stride: 4 * r.Dx(),
Rect: r,
}
}
// RGBA64 is an in-memory image whose At method returns color.RGBA64 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() color.Model { return color.RGBA64Model }
func (p *RGBA64) Bounds() Rectangle { return p.Rect }
func (p *RGBA64) At(x, y int) color.Color {
return p.RGBA64At(x, y)
}
func (p *RGBA64) RGBA64At(x, y int) color.RGBA64 {
if !(Point{x, y}.In(p.Rect)) {
return color.RGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
return color.RGBA64{
uint16(s[0])<<8 | uint16(s[1]),
uint16(s[2])<<8 | uint16(s[3]),
uint16(s[4])<<8 | uint16(s[5]),
uint16(s[6])<<8 | uint16(s[7]),
}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *RGBA64) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
}
func (p *RGBA64) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.RGBA64Model.Convert(c).(color.RGBA64)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(c1.R >> 8)
s[1] = uint8(c1.R)
s[2] = uint8(c1.G >> 8)
s[3] = uint8(c1.G)
s[4] = uint8(c1.B >> 8)
s[5] = uint8(c1.B)
s[6] = uint8(c1.A >> 8)
s[7] = uint8(c1.A)
}
func (p *RGBA64) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(c.R >> 8)
s[1] = uint8(c.R)
s[2] = uint8(c.G >> 8)
s[3] = uint8(c.G)
s[4] = uint8(c.B >> 8)
s[5] = uint8(c.B)
s[6] = uint8(c.A >> 8)
s[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 := p.PixOffset(r.Min.X, r.Min.Y)
return &RGBA64{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewRGBA64(r Rectangle) *RGBA64 {
return &RGBA64{
Pix: make([]uint8, pixelBufferLength(8, r, "RGBA64")),
Stride: 8 * r.Dx(),
Rect: r,
}
}
// NRGBA is an in-memory image whose At method returns color.NRGBA 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() color.Model { return color.NRGBAModel }
func (p *NRGBA) Bounds() Rectangle { return p.Rect }
func (p *NRGBA) At(x, y int) color.Color {
return p.NRGBAAt(x, y)
}
func (p *NRGBA) RGBA64At(x, y int) color.RGBA64 {
r, g, b, a := p.NRGBAAt(x, y).RGBA()
return color.RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)}
}
func (p *NRGBA) NRGBAAt(x, y int) color.NRGBA {
if !(Point{x, y}.In(p.Rect)) {
return color.NRGBA{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
return color.NRGBA{s[0], s[1], s[2], s[3]}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *NRGBA) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
}
func (p *NRGBA) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.NRGBAModel.Convert(c).(color.NRGBA)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c1.R
s[1] = c1.G
s[2] = c1.B
s[3] = c1.A
}
func (p *NRGBA) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
r, g, b, a := uint32(c.R), uint32(c.G), uint32(c.B), uint32(c.A)
if (a != 0) && (a != 0xffff) {
r = (r * 0xffff) / a
g = (g * 0xffff) / a
b = (b * 0xffff) / a
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(r >> 8)
s[1] = uint8(g >> 8)
s[2] = uint8(b >> 8)
s[3] = uint8(a >> 8)
}
func (p *NRGBA) SetNRGBA(x, y int, c color.NRGBA) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = c.R
s[1] = c.G
s[2] = c.B
s[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 := p.PixOffset(r.Min.X, r.Min.Y)
return &NRGBA{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewNRGBA(r Rectangle) *NRGBA {
return &NRGBA{
Pix: make([]uint8, pixelBufferLength(4, r, "NRGBA")),
Stride: 4 * r.Dx(),
Rect: r,
}
}
// NRGBA64 is an in-memory image whose At method returns color.NRGBA64 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() color.Model { return color.NRGBA64Model }
func (p *NRGBA64) Bounds() Rectangle { return p.Rect }
func (p *NRGBA64) At(x, y int) color.Color {
return p.NRGBA64At(x, y)
}
func (p *NRGBA64) RGBA64At(x, y int) color.RGBA64 {
r, g, b, a := p.NRGBA64At(x, y).RGBA()
return color.RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)}
}
func (p *NRGBA64) NRGBA64At(x, y int) color.NRGBA64 {
if !(Point{x, y}.In(p.Rect)) {
return color.NRGBA64{}
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
return color.NRGBA64{
uint16(s[0])<<8 | uint16(s[1]),
uint16(s[2])<<8 | uint16(s[3]),
uint16(s[4])<<8 | uint16(s[5]),
uint16(s[6])<<8 | uint16(s[7]),
}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *NRGBA64) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8
}
func (p *NRGBA64) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.NRGBA64Model.Convert(c).(color.NRGBA64)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(c1.R >> 8)
s[1] = uint8(c1.R)
s[2] = uint8(c1.G >> 8)
s[3] = uint8(c1.G)
s[4] = uint8(c1.B >> 8)
s[5] = uint8(c1.B)
s[6] = uint8(c1.A >> 8)
s[7] = uint8(c1.A)
}
func (p *NRGBA64) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
r, g, b, a := uint32(c.R), uint32(c.G), uint32(c.B), uint32(c.A)
if (a != 0) && (a != 0xffff) {
r = (r * 0xffff) / a
g = (g * 0xffff) / a
b = (b * 0xffff) / a
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(r >> 8)
s[1] = uint8(r)
s[2] = uint8(g >> 8)
s[3] = uint8(g)
s[4] = uint8(b >> 8)
s[5] = uint8(b)
s[6] = uint8(a >> 8)
s[7] = uint8(a)
}
func (p *NRGBA64) SetNRGBA64(x, y int, c color.NRGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857
s[0] = uint8(c.R >> 8)
s[1] = uint8(c.R)
s[2] = uint8(c.G >> 8)
s[3] = uint8(c.G)
s[4] = uint8(c.B >> 8)
s[5] = uint8(c.B)
s[6] = uint8(c.A >> 8)
s[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 := p.PixOffset(r.Min.X, r.Min.Y)
return &NRGBA64{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewNRGBA64(r Rectangle) *NRGBA64 {
return &NRGBA64{
Pix: make([]uint8, pixelBufferLength(8, r, "NRGBA64")),
Stride: 8 * r.Dx(),
Rect: r,
}
}
// Alpha is an in-memory image whose At method returns color.Alpha 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() color.Model { return color.AlphaModel }
func (p *Alpha) Bounds() Rectangle { return p.Rect }
func (p *Alpha) At(x, y int) color.Color {
return p.AlphaAt(x, y)
}
func (p *Alpha) RGBA64At(x, y int) color.RGBA64 {
a := uint16(p.AlphaAt(x, y).A)
a |= a << 8
return color.RGBA64{a, a, a, a}
}
func (p *Alpha) AlphaAt(x, y int) color.Alpha {
if !(Point{x, y}.In(p.Rect)) {
return color.Alpha{}
}
i := p.PixOffset(x, y)
return color.Alpha{p.Pix[i]}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *Alpha) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*1
}
func (p *Alpha) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
p.Pix[i] = color.AlphaModel.Convert(c).(color.Alpha).A
}
func (p *Alpha) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
p.Pix[i] = uint8(c.A >> 8)
}
func (p *Alpha) SetAlpha(x, y int, c color.Alpha) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
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 := p.PixOffset(r.Min.X, r.Min.Y)
return &Alpha{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewAlpha(r Rectangle) *Alpha {
return &Alpha{
Pix: make([]uint8, pixelBufferLength(1, r, "Alpha")),
Stride: 1 * r.Dx(),
Rect: r,
}
}
// Alpha16 is an in-memory image whose At method returns color.Alpha16 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() color.Model { return color.Alpha16Model }
func (p *Alpha16) Bounds() Rectangle { return p.Rect }
func (p *Alpha16) At(x, y int) color.Color {
return p.Alpha16At(x, y)
}
func (p *Alpha16) RGBA64At(x, y int) color.RGBA64 {
a := p.Alpha16At(x, y).A
return color.RGBA64{a, a, a, a}
}
func (p *Alpha16) Alpha16At(x, y int) color.Alpha16 {
if !(Point{x, y}.In(p.Rect)) {
return color.Alpha16{}
}
i := p.PixOffset(x, y)
return color.Alpha16{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *Alpha16) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
}
func (p *Alpha16) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.Alpha16Model.Convert(c).(color.Alpha16)
p.Pix[i+0] = uint8(c1.A >> 8)
p.Pix[i+1] = uint8(c1.A)
}
func (p *Alpha16) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
p.Pix[i+0] = uint8(c.A >> 8)
p.Pix[i+1] = uint8(c.A)
}
func (p *Alpha16) SetAlpha16(x, y int, c color.Alpha16) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
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 := p.PixOffset(r.Min.X, r.Min.Y)
return &Alpha16{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether 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 image with the given bounds.
func NewAlpha16(r Rectangle) *Alpha16 {
return &Alpha16{
Pix: make([]uint8, pixelBufferLength(2, r, "Alpha16")),
Stride: 2 * r.Dx(),
Rect: r,
}
}
// Gray is an in-memory image whose At method returns color.Gray 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() color.Model { return color.GrayModel }
func (p *Gray) Bounds() Rectangle { return p.Rect }
func (p *Gray) At(x, y int) color.Color {
return p.GrayAt(x, y)
}
func (p *Gray) RGBA64At(x, y int) color.RGBA64 {
gray := uint16(p.GrayAt(x, y).Y)
gray |= gray << 8
return color.RGBA64{gray, gray, gray, 0xffff}
}
func (p *Gray) GrayAt(x, y int) color.Gray {
if !(Point{x, y}.In(p.Rect)) {
return color.Gray{}
}
i := p.PixOffset(x, y)
return color.Gray{p.Pix[i]}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *Gray) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*1
}
func (p *Gray) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
p.Pix[i] = color.GrayModel.Convert(c).(color.Gray).Y
}
func (p *Gray) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
// This formula is the same as in color.grayModel.
gray := (19595*uint32(c.R) + 38470*uint32(c.G) + 7471*uint32(c.B) + 1<<15) >> 24
i := p.PixOffset(x, y)
p.Pix[i] = uint8(gray)
}
func (p *Gray) SetGray(x, y int, c color.Gray) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
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 := p.PixOffset(r.Min.X, r.Min.Y)
return &Gray{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether it is fully opaque.
func (p *Gray) Opaque() bool {
return true
}
// NewGray returns a new Gray image with the given bounds.
func NewGray(r Rectangle) *Gray {
return &Gray{
Pix: make([]uint8, pixelBufferLength(1, r, "Gray")),
Stride: 1 * r.Dx(),
Rect: r,
}
}
// Gray16 is an in-memory image whose At method returns color.Gray16 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() color.Model { return color.Gray16Model }
func (p *Gray16) Bounds() Rectangle { return p.Rect }
func (p *Gray16) At(x, y int) color.Color {
return p.Gray16At(x, y)
}
func (p *Gray16) RGBA64At(x, y int) color.RGBA64 {
gray := p.Gray16At(x, y).Y
return color.RGBA64{gray, gray, gray, 0xffff}
}
func (p *Gray16) Gray16At(x, y int) color.Gray16 {
if !(Point{x, y}.In(p.Rect)) {
return color.Gray16{}
}
i := p.PixOffset(x, y)
return color.Gray16{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *Gray16) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2
}
func (p *Gray16) Set(x, y int, c color.Color) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.Gray16Model.Convert(c).(color.Gray16)
p.Pix[i+0] = uint8(c1.Y >> 8)
p.Pix[i+1] = uint8(c1.Y)
}
func (p *Gray16) SetRGBA64(x, y int, c color.RGBA64) {
if !(Point{x, y}.In(p.Rect)) {
return
}
// This formula is the same as in color.gray16Model.
gray := (19595*uint32(c.R) + 38470*uint32(c.G) + 7471*uint32(c.B) + 1<<15) >> 16
i := p.PixOffset(x, y)
p.Pix[i+0] = uint8(gray >> 8)
p.Pix[i+1] = uint8(gray)
}
func (p *Gray16) SetGray16(x, y int, c color.Gray16) {
if !(Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
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() {