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Diffstat (limited to 'src/pkg/image/image.go')
-rw-r--r-- | src/pkg/image/image.go | 850 |
1 files changed, 850 insertions, 0 deletions
diff --git a/src/pkg/image/image.go b/src/pkg/image/image.go new file mode 100644 index 000000000..11def9435 --- /dev/null +++ b/src/pkg/image/image.go @@ -0,0 +1,850 @@ +// 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. +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} +} |