+++ /dev/null
-// 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
-
-// Color can convert itself to alpha-premultiplied RGBA, with a possible loss
-// of precision. Each value ranges within [0, 0xFFFF], but is represented by a
-// uint32 so that multiplying by a blend factor up to 0xFFFF will not overflow.
-type Color interface {
- RGBA() (r, g, b, a uint32)
-}
-
-// RGBAColor represents a traditional 32-bit alpha-premultiplied color,
-// having 8 bits for each of red, green, blue and alpha.
-type RGBAColor struct {
- R, G, B, A uint8
-}
-
-func (c RGBAColor) RGBA() (r, g, b, a uint32) {
- r = uint32(c.R)
- r |= r << 8
- g = uint32(c.G)
- g |= g << 8
- b = uint32(c.B)
- b |= b << 8
- a = uint32(c.A)
- a |= a << 8
- return
-}
-
-// RGBA64Color represents a 64-bit alpha-premultiplied color,
-// having 16 bits for each of red, green, blue and alpha.
-type RGBA64Color struct {
- R, G, B, A uint16
-}
-
-func (c RGBA64Color) RGBA() (r, g, b, a uint32) {
- return uint32(c.R), uint32(c.G), uint32(c.B), uint32(c.A)
-}
-
-// NRGBAColor represents a non-alpha-premultiplied 32-bit color.
-type NRGBAColor struct {
- R, G, B, A uint8
-}
-
-func (c NRGBAColor) RGBA() (r, g, b, a uint32) {
- r = uint32(c.R)
- r |= r << 8
- r *= uint32(c.A)
- r /= 0xff
- g = uint32(c.G)
- g |= g << 8
- g *= uint32(c.A)
- g /= 0xff
- b = uint32(c.B)
- b |= b << 8
- b *= uint32(c.A)
- b /= 0xff
- a = uint32(c.A)
- a |= a << 8
- return
-}
-
-// NRGBA64Color represents a non-alpha-premultiplied 64-bit color,
-// having 16 bits for each of red, green, blue and alpha.
-type NRGBA64Color struct {
- R, G, B, A uint16
-}
-
-func (c NRGBA64Color) RGBA() (r, g, b, a uint32) {
- r = uint32(c.R)
- r *= uint32(c.A)
- r /= 0xffff
- g = uint32(c.G)
- g *= uint32(c.A)
- g /= 0xffff
- b = uint32(c.B)
- b *= uint32(c.A)
- b /= 0xffff
- a = uint32(c.A)
- return
-}
-
-// AlphaColor represents an 8-bit alpha.
-type AlphaColor struct {
- A uint8
-}
-
-func (c AlphaColor) RGBA() (r, g, b, a uint32) {
- a = uint32(c.A)
- a |= a << 8
- return a, a, a, a
-}
-
-// Alpha16Color represents a 16-bit alpha.
-type Alpha16Color struct {
- A uint16
-}
-
-func (c Alpha16Color) RGBA() (r, g, b, a uint32) {
- a = uint32(c.A)
- return a, a, a, a
-}
-
-// GrayColor represents an 8-bit grayscale color.
-type GrayColor struct {
- Y uint8
-}
-
-func (c GrayColor) RGBA() (r, g, b, a uint32) {
- y := uint32(c.Y)
- y |= y << 8
- return y, y, y, 0xffff
-}
-
-// Gray16Color represents a 16-bit grayscale color.
-type Gray16Color struct {
- Y uint16
-}
-
-func (c Gray16Color) RGBA() (r, g, b, a uint32) {
- y := uint32(c.Y)
- return y, y, y, 0xffff
-}
-
-// ColorModel can convert foreign Colors, with a possible loss of precision,
-// to a Color from its own color model.
-type ColorModel interface {
- Convert(c Color) Color
-}
-
-// The ColorModelFunc type is an adapter to allow the use of an ordinary
-// color conversion function as a ColorModel. If f is such a function,
-// ColorModelFunc(f) is a ColorModel object that invokes f to implement
-// the conversion.
-type ColorModelFunc func(Color) Color
-
-func (f ColorModelFunc) Convert(c Color) Color {
- return f(c)
-}
-
-func toRGBAColor(c Color) Color {
- if _, ok := c.(RGBAColor); ok {
- return c
- }
- r, g, b, a := c.RGBA()
- return RGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)}
-}
-
-func toRGBA64Color(c Color) Color {
- if _, ok := c.(RGBA64Color); ok {
- return c
- }
- r, g, b, a := c.RGBA()
- return RGBA64Color{uint16(r), uint16(g), uint16(b), uint16(a)}
-}
-
-func toNRGBAColor(c Color) Color {
- if _, ok := c.(NRGBAColor); ok {
- return c
- }
- r, g, b, a := c.RGBA()
- if a == 0xffff {
- return NRGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), 0xff}
- }
- if a == 0 {
- return NRGBAColor{0, 0, 0, 0}
- }
- // Since Color.RGBA returns a alpha-premultiplied color, we should have r <= a && g <= a && b <= a.
- r = (r * 0xffff) / a
- g = (g * 0xffff) / a
- b = (b * 0xffff) / a
- return NRGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)}
-}
-
-func toNRGBA64Color(c Color) Color {
- if _, ok := c.(NRGBA64Color); ok {
- return c
- }
- r, g, b, a := c.RGBA()
- if a == 0xffff {
- return NRGBA64Color{uint16(r), uint16(g), uint16(b), 0xffff}
- }
- if a == 0 {
- return NRGBA64Color{0, 0, 0, 0}
- }
- // Since Color.RGBA returns a alpha-premultiplied color, we should have r <= a && g <= a && b <= a.
- r = (r * 0xffff) / a
- g = (g * 0xffff) / a
- b = (b * 0xffff) / a
- return NRGBA64Color{uint16(r), uint16(g), uint16(b), uint16(a)}
-}
-
-func toAlphaColor(c Color) Color {
- if _, ok := c.(AlphaColor); ok {
- return c
- }
- _, _, _, a := c.RGBA()
- return AlphaColor{uint8(a >> 8)}
-}
-
-func toAlpha16Color(c Color) Color {
- if _, ok := c.(Alpha16Color); ok {
- return c
- }
- _, _, _, a := c.RGBA()
- return Alpha16Color{uint16(a)}
-}
-
-func toGrayColor(c Color) Color {
- if _, ok := c.(GrayColor); ok {
- return c
- }
- r, g, b, _ := c.RGBA()
- y := (299*r + 587*g + 114*b + 500) / 1000
- return GrayColor{uint8(y >> 8)}
-}
-
-func toGray16Color(c Color) Color {
- if _, ok := c.(Gray16Color); ok {
- return c
- }
- r, g, b, _ := c.RGBA()
- y := (299*r + 587*g + 114*b + 500) / 1000
- return Gray16Color{uint16(y)}
-}
-
-// The ColorModel associated with RGBAColor.
-var RGBAColorModel ColorModel = ColorModelFunc(toRGBAColor)
-
-// The ColorModel associated with RGBA64Color.
-var RGBA64ColorModel ColorModel = ColorModelFunc(toRGBA64Color)
-
-// The ColorModel associated with NRGBAColor.
-var NRGBAColorModel ColorModel = ColorModelFunc(toNRGBAColor)
-
-// The ColorModel associated with NRGBA64Color.
-var NRGBA64ColorModel ColorModel = ColorModelFunc(toNRGBA64Color)
-
-// The ColorModel associated with AlphaColor.
-var AlphaColorModel ColorModel = ColorModelFunc(toAlphaColor)
-
-// The ColorModel associated with Alpha16Color.
-var Alpha16ColorModel ColorModel = ColorModelFunc(toAlpha16Color)
-
-// The ColorModel associated with GrayColor.
-var GrayColorModel ColorModel = ColorModelFunc(toGrayColor)
-
-// The ColorModel associated with Gray16Color.
-var Gray16ColorModel ColorModel = ColorModelFunc(toGray16Color)