428 lines
10 KiB
Go
428 lines
10 KiB
Go
// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
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package images
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import (
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"fmt"
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"image"
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"image/color"
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)
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var _ = fmt.Print
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type NRGBColor struct {
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R, G, B uint8
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}
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func (c NRGBColor) AsSharp() string {
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return fmt.Sprintf("#%02X%02X%02X", c.R, c.G, c.B)
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}
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func (c NRGBColor) RGBA() (r, g, b, a uint32) {
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r = uint32(c.R)
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r |= r << 8
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g = uint32(c.G)
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g |= g << 8
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b = uint32(c.B)
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b |= b << 8
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a = 65280 // ( 255 << 8 )
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return
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}
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// NRGB is an in-memory image whose At method returns NRGBColor values.
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type NRGB struct {
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// Pix holds the image's pixels, in R, G, B, A order. The pixel at
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// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
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Pix []uint8
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// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
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Stride int
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// Rect is the image's bounds.
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Rect image.Rectangle
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}
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func nrgbModel(c color.Color) color.Color {
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if _, ok := c.(NRGBColor); ok {
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return c
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}
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r, g, b, a := c.RGBA()
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if a == 0xffff {
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return NRGBColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8)}
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}
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if a == 0 {
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return NRGBColor{0, 0, 0}
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}
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// Since Color.RGBA returns an alpha-premultiplied color, we should have r <= a && g <= a && b <= a.
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r = (r * 0xffff) / a
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g = (g * 0xffff) / a
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b = (b * 0xffff) / a
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return NRGBColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8)}
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}
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var NRGBModel color.Model = color.ModelFunc(nrgbModel)
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func (p *NRGB) ColorModel() color.Model { return NRGBModel }
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func (p *NRGB) Bounds() image.Rectangle { return p.Rect }
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func (p *NRGB) At(x, y int) color.Color {
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return p.NRGBAt(x, y)
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}
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func (p *NRGB) NRGBAt(x, y int) NRGBColor {
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if !(image.Point{x, y}.In(p.Rect)) {
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return NRGBColor{}
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}
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i := p.PixOffset(x, y)
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s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
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return NRGBColor{s[0], s[1], s[2]}
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}
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// PixOffset returns the index of the first element of Pix that corresponds to
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// the pixel at (x, y).
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func (p *NRGB) PixOffset(x, y int) int {
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return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
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}
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func (p *NRGB) Set(x, y int, c color.Color) {
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if !(image.Point{x, y}.In(p.Rect)) {
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return
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}
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i := p.PixOffset(x, y)
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c1 := NRGBModel.Convert(c).(NRGBColor)
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s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
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s[0] = c1.R
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s[1] = c1.G
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s[2] = c1.B
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}
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func (p *NRGB) SetRGBA64(x, y int, c color.RGBA64) {
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if !(image.Point{x, y}.In(p.Rect)) {
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return
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}
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r, g, b, a := uint32(c.R), uint32(c.G), uint32(c.B), uint32(c.A)
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if (a != 0) && (a != 0xffff) {
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r = (r * 0xffff) / a
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g = (g * 0xffff) / a
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b = (b * 0xffff) / a
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}
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i := p.PixOffset(x, y)
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s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
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s[0] = uint8(r >> 8)
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s[1] = uint8(g >> 8)
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s[2] = uint8(b >> 8)
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}
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func (p *NRGB) SetNRGBA(x, y int, c color.NRGBA) {
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if !(image.Point{x, y}.In(p.Rect)) {
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return
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}
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i := p.PixOffset(x, y)
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s := p.Pix[i : i+3 : i+3] // Small cap improves performance, see https://golang.org/issue/27857
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s[0] = c.R
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s[1] = c.G
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s[2] = c.B
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}
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// SubImage returns an image representing the portion of the image p visible
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// through r. The returned value shares pixels with the original image.
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func (p *NRGB) SubImage(r image.Rectangle) image.Image {
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r = r.Intersect(p.Rect)
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// If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside
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// either r1 or r2 if the intersection is empty. Without explicitly checking for
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// this, the Pix[i:] expression below can panic.
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if r.Empty() {
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return &NRGB{}
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}
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i := p.PixOffset(r.Min.X, r.Min.Y)
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return &NRGB{
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Pix: p.Pix[i:],
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Stride: p.Stride,
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Rect: r,
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}
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}
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// Opaque scans the entire image and reports whether it is fully opaque.
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func (p *NRGB) Opaque() bool { return true }
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type scanner_rgb struct {
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image image.Image
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w, h int
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palette []NRGBColor
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opaque_base []float64
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opaque_base_uint []uint8
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}
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func (s scanner_rgb) bytes_per_pixel() int { return 3 }
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func (s scanner_rgb) bounds() image.Rectangle { return s.image.Bounds() }
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func blend(dest []uint8, base []float64, r, g, b, a uint8) {
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alpha := float64(a) / 255.0
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dest[0] = uint8(alpha*float64(r) + (1.0-alpha)*base[0])
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dest[1] = uint8(alpha*float64(g) + (1.0-alpha)*base[1])
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dest[2] = uint8(alpha*float64(b) + (1.0-alpha)*base[2])
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}
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func newScannerRGB(img image.Image, opaque_base NRGBColor) *scanner_rgb {
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s := &scanner_rgb{
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image: img, w: img.Bounds().Dx(), h: img.Bounds().Dy(),
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opaque_base: []float64{float64(opaque_base.R), float64(opaque_base.G), float64(opaque_base.B)}[0:3:3],
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opaque_base_uint: []uint8{opaque_base.R, opaque_base.G, opaque_base.B}[0:3:3],
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}
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if img, ok := img.(*image.Paletted); ok {
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s.palette = make([]NRGBColor, len(img.Palette))
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d := make([]uint8, 3)
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for i := 0; i < len(img.Palette); i++ {
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r, g, b, a := img.Palette[i].RGBA()
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switch a {
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case 0:
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s.palette[i] = opaque_base
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default:
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blend(d, s.opaque_base, uint8((r*0xffff/a)>>8), uint8((g*0xffff/a)>>8), uint8((b*0xffff/a)>>8), uint8(a>>8))
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s.palette[i] = NRGBColor{d[0], d[1], d[2]}
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}
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}
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}
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return s
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}
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// scan scans the given rectangular region of the image into dst.
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func (s *scanner_rgb) scan(x1, y1, x2, y2 int, dst []uint8) {
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switch img := s.image.(type) {
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case *image.NRGBA:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1*4
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for x := x1; x < x2; x++ {
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blend(dst[j:j+3:j+3], s.opaque_base, img.Pix[i], img.Pix[i+1], img.Pix[i+2], img.Pix[i+3])
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j += 3
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i += 4
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}
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}
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case *image.NRGBA64:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1*8
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for x := x1; x < x2; x++ {
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blend(dst[j:j+3:j+3], s.opaque_base, img.Pix[i], img.Pix[i+2], img.Pix[i+4], img.Pix[i+6])
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j += 3
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i += 8
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}
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}
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case *image.RGBA:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1*4
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for x := x1; x < x2; x++ {
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d := dst[j : j+3 : j+3]
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a := img.Pix[i+3]
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switch a {
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case 0:
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d[0] = s.opaque_base_uint[0]
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d[1] = s.opaque_base_uint[1]
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d[2] = s.opaque_base_uint[2]
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case 0xff:
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s := img.Pix[i : i+3 : i+3]
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d[0] = s[0]
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d[1] = s[1]
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d[2] = s[2]
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default:
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r16 := uint16(img.Pix[i])
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g16 := uint16(img.Pix[i+1])
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b16 := uint16(img.Pix[i+2])
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a16 := uint16(a)
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blend(d, s.opaque_base, uint8(r16*0xff/a16), uint8(g16*0xff/a16), uint8(b16*0xff/a16), a)
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}
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j += 3
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i += 4
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}
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}
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case *image.RGBA64:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1*8
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for x := x1; x < x2; x++ {
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src := img.Pix[i : i+8 : i+8]
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d := dst[j : j+3 : j+3]
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a := src[6]
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switch a {
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case 0:
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d[0] = s.opaque_base_uint[0]
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d[1] = s.opaque_base_uint[1]
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d[2] = s.opaque_base_uint[2]
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case 0xff:
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d[0] = src[0]
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d[1] = src[2]
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d[2] = src[4]
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default:
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r32 := uint32(src[0])<<8 | uint32(src[1])
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g32 := uint32(src[2])<<8 | uint32(src[3])
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b32 := uint32(src[4])<<8 | uint32(src[5])
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a32 := uint32(src[6])<<8 | uint32(src[7])
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blend(d, s.opaque_base, uint8((r32*0xffff/a32)>>8), uint8((g32*0xffff/a32)>>8), uint8((b32*0xffff/a32)>>8), a)
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}
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j += 3
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i += 8
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}
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}
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case *image.Gray:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1
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for x := x1; x < x2; x++ {
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c := img.Pix[i]
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d := dst[j : j+3 : j+3]
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d[0] = c
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d[1] = c
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d[2] = c
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j += 3
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i++
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}
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}
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case *image.Gray16:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1*2
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for x := x1; x < x2; x++ {
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c := img.Pix[i]
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d := dst[j : j+3 : j+3]
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d[0] = c
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d[1] = c
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d[2] = c
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j += 3
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i += 2
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}
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}
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case *image.YCbCr:
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j := 0
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x1 += img.Rect.Min.X
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x2 += img.Rect.Min.X
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y1 += img.Rect.Min.Y
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y2 += img.Rect.Min.Y
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hy := img.Rect.Min.Y / 2
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hx := img.Rect.Min.X / 2
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for y := y1; y < y2; y++ {
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iy := (y-img.Rect.Min.Y)*img.YStride + (x1 - img.Rect.Min.X)
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var yBase int
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switch img.SubsampleRatio {
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case image.YCbCrSubsampleRatio444, image.YCbCrSubsampleRatio422:
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yBase = (y - img.Rect.Min.Y) * img.CStride
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case image.YCbCrSubsampleRatio420, image.YCbCrSubsampleRatio440:
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yBase = (y/2 - hy) * img.CStride
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}
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for x := x1; x < x2; x++ {
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var ic int
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switch img.SubsampleRatio {
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case image.YCbCrSubsampleRatio444, image.YCbCrSubsampleRatio440:
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ic = yBase + (x - img.Rect.Min.X)
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case image.YCbCrSubsampleRatio422, image.YCbCrSubsampleRatio420:
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ic = yBase + (x/2 - hx)
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default:
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ic = img.COffset(x, y)
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}
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yy1 := int32(img.Y[iy]) * 0x10101
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cb1 := int32(img.Cb[ic]) - 128
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cr1 := int32(img.Cr[ic]) - 128
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r := yy1 + 91881*cr1
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if uint32(r)&0xff000000 == 0 {
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r >>= 16
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} else {
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r = ^(r >> 31)
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}
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g := yy1 - 22554*cb1 - 46802*cr1
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if uint32(g)&0xff000000 == 0 {
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g >>= 16
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} else {
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g = ^(g >> 31)
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}
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b := yy1 + 116130*cb1
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if uint32(b)&0xff000000 == 0 {
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b >>= 16
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} else {
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b = ^(b >> 31)
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}
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d := dst[j : j+3 : j+3]
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d[0] = uint8(r)
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d[1] = uint8(g)
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d[2] = uint8(b)
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iy++
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j += 3
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}
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}
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case *image.Paletted:
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j := 0
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for y := y1; y < y2; y++ {
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i := y*img.Stride + x1
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for x := x1; x < x2; x++ {
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c := s.palette[img.Pix[i]]
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d := dst[j : j+3 : j+3]
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d[0] = c.R
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d[1] = c.G
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d[2] = c.B
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j += 3
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i++
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}
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}
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default:
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j := 0
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b := s.image.Bounds()
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x1 += b.Min.X
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x2 += b.Min.X
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y1 += b.Min.Y
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y2 += b.Min.Y
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for y := y1; y < y2; y++ {
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for x := x1; x < x2; x++ {
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r16, g16, b16, a16 := s.image.At(x, y).RGBA()
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d := dst[j : j+3 : j+3]
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switch a16 {
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case 0xffff:
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d[0] = uint8(r16 >> 8)
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d[1] = uint8(g16 >> 8)
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d[2] = uint8(b16 >> 8)
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case 0:
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d[0] = s.opaque_base_uint[0]
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d[1] = s.opaque_base_uint[1]
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d[2] = s.opaque_base_uint[2]
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default:
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blend(d, s.opaque_base, uint8(((r16*0xffff)/a16)>>8), uint8(((g16*0xffff)/a16)>>8), uint8(((b16*0xffff)/a16)>>8), uint8(a16>>8))
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}
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j += 3
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}
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}
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}
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}
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func (self *Context) paste_nrgb_onto_opaque(background *NRGB, img image.Image, pos image.Point, bgcol *NRGBColor) {
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bg := NRGBColor{}
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if bgcol != nil {
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bg = *bgcol
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}
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src := newScannerRGB(img, bg)
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self.run_paste(src, background, pos, func(dst []byte) {})
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}
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func NewNRGB(r image.Rectangle) *NRGB {
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return &NRGB{
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Pix: make([]uint8, 3*r.Dx()*r.Dy()),
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Stride: 3 * r.Dx(),
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Rect: r,
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}
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}
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