webp/nycbcra: delete deprecated package
This package has been deprecated since Go 1.6, which is long ago. There's a warning printed whenever this package is imported, which helped people migrate away from it by now. Delete it since it's unused and unsupported. Change-Id: If84b631ebff6530cdb955af34fa7b84d50130166 Reviewed-on: https://go-review.googlesource.com/c/148570 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Dmitri Shuralyov
parent
55919307b5
commit
6f5d68baf1
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package nycbcra provides non-alpha-premultiplied Y'CbCr-with-alpha image and
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// color types.
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//
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// Deprecated: as of Go 1.6. Use the standard image and image/color packages
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// instead.
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package nycbcra // import "golang.org/x/image/webp/nycbcra"
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import (
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"image"
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"image/color"
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)
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func init() {
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println("The golang.org/x/image/webp/nycbcra package is deprecated, as of Go 1.6. " +
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"Use the standard image and image/color packages instead.")
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}
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// TODO: move this to the standard image and image/color packages, so that the
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// image/draw package can have fast-path code. Moving would rename:
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// nycbcra.Color to color.NYCbCrA
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// nycbcra.ColorModel to color.NYCbCrAModel
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// nycbcra.Image to image.NYCbCrA
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// Color represents a non-alpha-premultiplied Y'CbCr-with-alpha color, having
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// 8 bits each for one luma, two chroma and one alpha component.
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type Color struct {
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color.YCbCr
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A uint8
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}
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func (c Color) RGBA() (r, g, b, a uint32) {
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r8, g8, b8 := color.YCbCrToRGB(c.Y, c.Cb, c.Cr)
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a = uint32(c.A) * 0x101
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r = uint32(r8) * 0x101 * a / 0xffff
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g = uint32(g8) * 0x101 * a / 0xffff
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b = uint32(b8) * 0x101 * a / 0xffff
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return
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}
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// ColorModel is the Model for non-alpha-premultiplied Y'CbCr-with-alpha colors.
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var ColorModel color.Model = color.ModelFunc(nYCbCrAModel)
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func nYCbCrAModel(c color.Color) color.Color {
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switch c := c.(type) {
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case Color:
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return c
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case color.YCbCr:
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return Color{c, 0xff}
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}
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r, g, b, a := c.RGBA()
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// Convert from alpha-premultiplied to non-alpha-premultiplied.
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if a != 0 {
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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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y, u, v := color.RGBToYCbCr(uint8(r>>8), uint8(g>>8), uint8(b>>8))
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return Color{color.YCbCr{Y: y, Cb: u, Cr: v}, uint8(a >> 8)}
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}
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// Image is an in-memory image of non-alpha-premultiplied Y'CbCr-with-alpha
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// colors. A and AStride are analogous to the Y and YStride fields of the
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// embedded YCbCr.
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type Image struct {
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image.YCbCr
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A []uint8
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AStride int
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}
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func (p *Image) ColorModel() color.Model {
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return ColorModel
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}
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func (p *Image) At(x, y int) color.Color {
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return p.NYCbCrAAt(x, y)
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}
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func (p *Image) NYCbCrAAt(x, y int) Color {
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if !(image.Point{X: x, Y: y}.In(p.Rect)) {
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return Color{}
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}
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yi := p.YOffset(x, y)
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ci := p.COffset(x, y)
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ai := p.AOffset(x, y)
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return Color{
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color.YCbCr{
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Y: p.Y[yi],
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Cb: p.Cb[ci],
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Cr: p.Cr[ci],
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},
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p.A[ai],
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}
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}
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// AOffset returns the index of the first element of A that corresponds to
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// the pixel at (x, y).
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func (p *Image) AOffset(x, y int) int {
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return (y-p.Rect.Min.Y)*p.AStride + (x - p.Rect.Min.X)
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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 *Image) SubImage(r image.Rectangle) image.Image {
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// TODO: share code with image.NewYCbCr when this type moves into the
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// standard image package.
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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 &Image{
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YCbCr: image.YCbCr{
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SubsampleRatio: p.SubsampleRatio,
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},
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}
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}
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yi := p.YOffset(r.Min.X, r.Min.Y)
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ci := p.COffset(r.Min.X, r.Min.Y)
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ai := p.AOffset(r.Min.X, r.Min.Y)
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return &Image{
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YCbCr: image.YCbCr{
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Y: p.Y[yi:],
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Cb: p.Cb[ci:],
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Cr: p.Cr[ci:],
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SubsampleRatio: p.SubsampleRatio,
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YStride: p.YStride,
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CStride: p.CStride,
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Rect: r,
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},
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A: p.A[ai:],
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AStride: p.AStride,
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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 *Image) Opaque() bool {
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if p.Rect.Empty() {
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return true
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}
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i0, i1 := 0, p.Rect.Dx()
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for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
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for _, a := range p.A[i0:i1] {
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if a != 0xff {
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return false
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}
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}
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i0 += p.AStride
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i1 += p.AStride
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}
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return true
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}
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// New returns a new Image with the given bounds and subsample ratio.
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func New(r image.Rectangle, subsampleRatio image.YCbCrSubsampleRatio) *Image {
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// TODO: share code with image.NewYCbCr when this type moves into the
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// standard image package.
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w, h, cw, ch := r.Dx(), r.Dy(), 0, 0
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switch subsampleRatio {
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case image.YCbCrSubsampleRatio422:
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cw = (r.Max.X+1)/2 - r.Min.X/2
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ch = h
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case image.YCbCrSubsampleRatio420:
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cw = (r.Max.X+1)/2 - r.Min.X/2
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ch = (r.Max.Y+1)/2 - r.Min.Y/2
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case image.YCbCrSubsampleRatio440:
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cw = w
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ch = (r.Max.Y+1)/2 - r.Min.Y/2
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default:
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// Default to 4:4:4 subsampling.
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cw = w
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ch = h
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}
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b := make([]byte, 2*w*h+2*cw*ch)
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// TODO: use s[i:j:k] notation to set the cap.
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return &Image{
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YCbCr: image.YCbCr{
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Y: b[:w*h],
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Cb: b[w*h+0*cw*ch : w*h+1*cw*ch],
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Cr: b[w*h+1*cw*ch : w*h+2*cw*ch],
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SubsampleRatio: subsampleRatio,
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YStride: w,
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CStride: cw,
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Rect: r,
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},
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A: b[w*h+2*cw*ch:],
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AStride: w,
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}
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}
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