Adding upstream version 1.17.13.upstream/1.17.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 328 insertions, 0 deletions

diff --git a/src/image/ycbcr.go b/src/image/ycbcr.go
new file mode 100644
index 0000000..328b90d
--- /dev/null
+++ b/src/image/ycbcr.go
@@ -0,0 +1,328 @@
+// Copyright 2011 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
+
+import (
+	"image/color"
+)
+
+// YCbCrSubsampleRatio is the chroma subsample ratio used in a YCbCr image.
+type YCbCrSubsampleRatio int
+
+const (
+	YCbCrSubsampleRatio444 YCbCrSubsampleRatio = iota
+	YCbCrSubsampleRatio422
+	YCbCrSubsampleRatio420
+	YCbCrSubsampleRatio440
+	YCbCrSubsampleRatio411
+	YCbCrSubsampleRatio410
+)
+
+func (s YCbCrSubsampleRatio) String() string {
+	switch s {
+	case YCbCrSubsampleRatio444:
+		return "YCbCrSubsampleRatio444"
+	case YCbCrSubsampleRatio422:
+		return "YCbCrSubsampleRatio422"
+	case YCbCrSubsampleRatio420:
+		return "YCbCrSubsampleRatio420"
+	case YCbCrSubsampleRatio440:
+		return "YCbCrSubsampleRatio440"
+	case YCbCrSubsampleRatio411:
+		return "YCbCrSubsampleRatio411"
+	case YCbCrSubsampleRatio410:
+		return "YCbCrSubsampleRatio410"
+	}
+	return "YCbCrSubsampleRatioUnknown"
+}
+
+// YCbCr is an in-memory image of Y'CbCr colors. There is one Y sample per
+// pixel, but each Cb and Cr sample can span one or more pixels.
+// YStride is the Y slice index delta between vertically adjacent pixels.
+// CStride is the Cb and Cr slice index delta between vertically adjacent pixels
+// that map to separate chroma samples.
+// It is not an absolute requirement, but YStride and len(Y) are typically
+// multiples of 8, and:
+//	For 4:4:4, CStride == YStride/1 && len(Cb) == len(Cr) == len(Y)/1.
+//	For 4:2:2, CStride == YStride/2 && len(Cb) == len(Cr) == len(Y)/2.
+//	For 4:2:0, CStride == YStride/2 && len(Cb) == len(Cr) == len(Y)/4.
+//	For 4:4:0, CStride == YStride/1 && len(Cb) == len(Cr) == len(Y)/2.
+//	For 4:1:1, CStride == YStride/4 && len(Cb) == len(Cr) == len(Y)/4.
+//	For 4:1:0, CStride == YStride/4 && len(Cb) == len(Cr) == len(Y)/8.
+type YCbCr struct {
+	Y, Cb, Cr      []uint8
+	YStride        int
+	CStride        int
+	SubsampleRatio YCbCrSubsampleRatio
+	Rect           Rectangle
+}
+
+func (p *YCbCr) ColorModel() color.Model {
+	return color.YCbCrModel
+}
+
+func (p *YCbCr) Bounds() Rectangle {
+	return p.Rect
+}
+
+func (p *YCbCr) At(x, y int) color.Color {
+	return p.YCbCrAt(x, y)
+}
+
+func (p *YCbCr) RGBA64At(x, y int) color.RGBA64 {
+	r, g, b, a := p.YCbCrAt(x, y).RGBA()
+	return color.RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)}
+}
+
+func (p *YCbCr) YCbCrAt(x, y int) color.YCbCr {
+	if !(Point{x, y}.In(p.Rect)) {
+		return color.YCbCr{}
+	}
+	yi := p.YOffset(x, y)
+	ci := p.COffset(x, y)
+	return color.YCbCr{
+		p.Y[yi],
+		p.Cb[ci],
+		p.Cr[ci],
+	}
+}
+
+// YOffset returns the index of the first element of Y that corresponds to
+// the pixel at (x, y).
+func (p *YCbCr) YOffset(x, y int) int {
+	return (y-p.Rect.Min.Y)*p.YStride + (x - p.Rect.Min.X)
+}
+
+// COffset returns the index of the first element of Cb or Cr that corresponds
+// to the pixel at (x, y).
+func (p *YCbCr) COffset(x, y int) int {
+	switch p.SubsampleRatio {
+	case YCbCrSubsampleRatio422:
+		return (y-p.Rect.Min.Y)*p.CStride + (x/2 - p.Rect.Min.X/2)
+	case YCbCrSubsampleRatio420:
+		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x/2 - p.Rect.Min.X/2)
+	case YCbCrSubsampleRatio440:
+		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x - p.Rect.Min.X)
+	case YCbCrSubsampleRatio411:
+		return (y-p.Rect.Min.Y)*p.CStride + (x/4 - p.Rect.Min.X/4)
+	case YCbCrSubsampleRatio410:
+		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x/4 - p.Rect.Min.X/4)
+	}
+	// Default to 4:4:4 subsampling.
+	return (y-p.Rect.Min.Y)*p.CStride + (x - p.Rect.Min.X)
+}
+
+// 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 *YCbCr) 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 &YCbCr{
+			SubsampleRatio: p.SubsampleRatio,
+		}
+	}
+	yi := p.YOffset(r.Min.X, r.Min.Y)
+	ci := p.COffset(r.Min.X, r.Min.Y)
+	return &YCbCr{
+		Y:              p.Y[yi:],
+		Cb:             p.Cb[ci:],
+		Cr:             p.Cr[ci:],
+		SubsampleRatio: p.SubsampleRatio,
+		YStride:        p.YStride,
+		CStride:        p.CStride,
+		Rect:           r,
+	}
+}
+
+func (p *YCbCr) Opaque() bool {
+	return true
+}
+
+func yCbCrSize(r Rectangle, subsampleRatio YCbCrSubsampleRatio) (w, h, cw, ch int) {
+	w, h = r.Dx(), r.Dy()
+	switch subsampleRatio {
+	case YCbCrSubsampleRatio422:
+		cw = (r.Max.X+1)/2 - r.Min.X/2
+		ch = h
+	case YCbCrSubsampleRatio420:
+		cw = (r.Max.X+1)/2 - r.Min.X/2
+		ch = (r.Max.Y+1)/2 - r.Min.Y/2
+	case YCbCrSubsampleRatio440:
+		cw = w
+		ch = (r.Max.Y+1)/2 - r.Min.Y/2
+	case YCbCrSubsampleRatio411:
+		cw = (r.Max.X+3)/4 - r.Min.X/4
+		ch = h
+	case YCbCrSubsampleRatio410:
+		cw = (r.Max.X+3)/4 - r.Min.X/4
+		ch = (r.Max.Y+1)/2 - r.Min.Y/2
+	default:
+		// Default to 4:4:4 subsampling.
+		cw = w
+		ch = h
+	}
+	return
+}
+
+// NewYCbCr returns a new YCbCr image with the given bounds and subsample
+// ratio.
+func NewYCbCr(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr {
+	w, h, cw, ch := yCbCrSize(r, subsampleRatio)
+
+	// totalLength should be the same as i2, below, for a valid Rectangle r.
+	totalLength := add2NonNeg(
+		mul3NonNeg(1, w, h),
+		mul3NonNeg(2, cw, ch),
+	)
+	if totalLength < 0 {
+		panic("image: NewYCbCr Rectangle has huge or negative dimensions")
+	}
+
+	i0 := w*h + 0*cw*ch
+	i1 := w*h + 1*cw*ch
+	i2 := w*h + 2*cw*ch
+	b := make([]byte, i2)
+	return &YCbCr{
+		Y:              b[:i0:i0],
+		Cb:             b[i0:i1:i1],
+		Cr:             b[i1:i2:i2],
+		SubsampleRatio: subsampleRatio,
+		YStride:        w,
+		CStride:        cw,
+		Rect:           r,
+	}
+}
+
+// NYCbCrA is an in-memory image of non-alpha-premultiplied Y'CbCr-with-alpha
+// colors. A and AStride are analogous to the Y and YStride fields of the
+// embedded YCbCr.
+type NYCbCrA struct {
+	YCbCr
+	A       []uint8
+	AStride int
+}
+
+func (p *NYCbCrA) ColorModel() color.Model {
+	return color.NYCbCrAModel
+}
+
+func (p *NYCbCrA) At(x, y int) color.Color {
+	return p.NYCbCrAAt(x, y)
+}
+
+func (p *NYCbCrA) RGBA64At(x, y int) color.RGBA64 {
+	r, g, b, a := p.NYCbCrAAt(x, y).RGBA()
+	return color.RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)}
+}
+
+func (p *NYCbCrA) NYCbCrAAt(x, y int) color.NYCbCrA {
+	if !(Point{X: x, Y: y}.In(p.Rect)) {
+		return color.NYCbCrA{}
+	}
+	yi := p.YOffset(x, y)
+	ci := p.COffset(x, y)
+	ai := p.AOffset(x, y)
+	return color.NYCbCrA{
+		color.YCbCr{
+			Y:  p.Y[yi],
+			Cb: p.Cb[ci],
+			Cr: p.Cr[ci],
+		},
+		p.A[ai],
+	}
+}
+
+// AOffset returns the index of the first element of A that corresponds to the
+// pixel at (x, y).
+func (p *NYCbCrA) AOffset(x, y int) int {
+	return (y-p.Rect.Min.Y)*p.AStride + (x - p.Rect.Min.X)
+}
+
+// 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 *NYCbCrA) 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 &NYCbCrA{
+			YCbCr: YCbCr{
+				SubsampleRatio: p.SubsampleRatio,
+			},
+		}
+	}
+	yi := p.YOffset(r.Min.X, r.Min.Y)
+	ci := p.COffset(r.Min.X, r.Min.Y)
+	ai := p.AOffset(r.Min.X, r.Min.Y)
+	return &NYCbCrA{
+		YCbCr: YCbCr{
+			Y:              p.Y[yi:],
+			Cb:             p.Cb[ci:],
+			Cr:             p.Cr[ci:],
+			SubsampleRatio: p.SubsampleRatio,
+			YStride:        p.YStride,
+			CStride:        p.CStride,
+			Rect:           r,
+		},
+		A:       p.A[ai:],
+		AStride: p.AStride,
+	}
+}
+
+// Opaque scans the entire image and reports whether it is fully opaque.
+func (p *NYCbCrA) 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 _, a := range p.A[i0:i1] {
+			if a != 0xff {
+				return false
+			}
+		}
+		i0 += p.AStride
+		i1 += p.AStride
+	}
+	return true
+}
+
+// NewNYCbCrA returns a new NYCbCrA image with the given bounds and subsample
+// ratio.
+func NewNYCbCrA(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *NYCbCrA {
+	w, h, cw, ch := yCbCrSize(r, subsampleRatio)
+
+	// totalLength should be the same as i3, below, for a valid Rectangle r.
+	totalLength := add2NonNeg(
+		mul3NonNeg(2, w, h),
+		mul3NonNeg(2, cw, ch),
+	)
+	if totalLength < 0 {
+		panic("image: NewNYCbCrA Rectangle has huge or negative dimension")
+	}
+
+	i0 := 1*w*h + 0*cw*ch
+	i1 := 1*w*h + 1*cw*ch
+	i2 := 1*w*h + 2*cw*ch
+	i3 := 2*w*h + 2*cw*ch
+	b := make([]byte, i3)
+	return &NYCbCrA{
+		YCbCr: YCbCr{
+			Y:              b[:i0:i0],
+			Cb:             b[i0:i1:i1],
+			Cr:             b[i1:i2:i2],
+			SubsampleRatio: subsampleRatio,
+			YStride:        w,
+			CStride:        cw,
+			Rect:           r,
+		},
+		A:       b[i2:],
+		AStride: w,
+	}
+}