From cdf7654062412a3213a217e34ce2c563653d140d Mon Sep 17 00:00:00 2001 From: David Crawshaw Date: Mon, 16 Jan 2012 16:02:31 +1100 Subject: [PATCH] image/color: simplify documentation R=nigeltao, dsymonds, adg CC=golang-dev https://golang.org/cl/5544073 --- src/pkg/image/color/color.go | 63 ++++++++++++++++++------------------ src/pkg/image/color/ycbcr.go | 12 +++---- 2 files changed, 38 insertions(+), 37 deletions(-) diff --git a/src/pkg/image/color/color.go b/src/pkg/image/color/color.go index 2948db7f38c..29a7b8a4001 100644 --- a/src/pkg/image/color/color.go +++ b/src/pkg/image/color/color.go @@ -152,26 +152,35 @@ func (m *modelFunc) Convert(c Color) Color { return m.f(c) } -// RGBAModel is the Model for RGBA colors. -var RGBAModel Model = ModelFunc(func(c Color) Color { +// Models for the standard color types. +var ( + RGBAModel Model = ModelFunc(rgbaModel) + RGBA64Model Model = ModelFunc(rgba64Model) + NRGBAModel Model = ModelFunc(nrgbaModel) + NRGBA64Model Model = ModelFunc(nrgba64Model) + AlphaModel Model = ModelFunc(alphaModel) + Alpha16Model Model = ModelFunc(alpha16Model) + GrayModel Model = ModelFunc(grayModel) + Gray16Model Model = ModelFunc(gray16Model) +) + +func rgbaModel(c Color) Color { if _, ok := c.(RGBA); ok { return c } r, g, b, a := c.RGBA() return RGBA{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} -}) +} -// RGBAModel is the Model for RGBA64 colors. -var RGBA64Model Model = ModelFunc(func(c Color) Color { +func rgba64Model(c Color) Color { if _, ok := c.(RGBA64); ok { return c } r, g, b, a := c.RGBA() return RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)} -}) +} -// NRGBAModel is the Model for NRGBA colors. -var NRGBAModel Model = ModelFunc(func(c Color) Color { +func nrgbaModel(c Color) Color { if _, ok := c.(NRGBA); ok { return c } @@ -187,10 +196,9 @@ var NRGBAModel Model = ModelFunc(func(c Color) Color { g = (g * 0xffff) / a b = (b * 0xffff) / a return NRGBA{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} -}) +} -// NRGBAModel is the Model for NRGBA64 colors. -var NRGBA64Model Model = ModelFunc(func(c Color) Color { +func nrgba64Model(c Color) Color { if _, ok := c.(NRGBA64); ok { return c } @@ -206,45 +214,41 @@ var NRGBA64Model Model = ModelFunc(func(c Color) Color { g = (g * 0xffff) / a b = (b * 0xffff) / a return NRGBA64{uint16(r), uint16(g), uint16(b), uint16(a)} -}) +} -// AlphaModel is the Model for Alpha colors. -var AlphaModel Model = ModelFunc(func(c Color) Color { +func alphaModel(c Color) Color { if _, ok := c.(Alpha); ok { return c } _, _, _, a := c.RGBA() return Alpha{uint8(a >> 8)} -}) +} -// Alpha16Model is the Model for Alpha16 colors. -var Alpha16Model Model = ModelFunc(func(c Color) Color { +func alpha16Model(c Color) Color { if _, ok := c.(Alpha16); ok { return c } _, _, _, a := c.RGBA() return Alpha16{uint16(a)} -}) +} -// GrayModel is the Model for Gray colors. -var GrayModel Model = ModelFunc(func(c Color) Color { +func grayModel(c Color) Color { if _, ok := c.(Gray); ok { return c } r, g, b, _ := c.RGBA() y := (299*r + 587*g + 114*b + 500) / 1000 return Gray{uint8(y >> 8)} -}) +} -// Gray16Model is the Model for Gray16 colors. -var Gray16Model Model = ModelFunc(func(c Color) Color { +func gray16Model(c Color) Color { if _, ok := c.(Gray16); ok { return c } r, g, b, _ := c.RGBA() y := (299*r + 587*g + 114*b + 500) / 1000 return Gray16{uint16(y)} -}) +} // Palette is a palette of colors. type Palette []Color @@ -290,13 +294,10 @@ func (p Palette) Index(c Color) int { return ret } +// Standard colors. var ( - // Black is an opaque black Color. - Black = Gray16{0} - // White is an opaque white Color. - White = Gray16{0xffff} - // Transparent is a fully transparent Color. + Black = Gray16{0} + White = Gray16{0xffff} Transparent = Alpha16{0} - // Opaque is a fully opaque Color. - Opaque = Alpha16{0xffff} + Opaque = Alpha16{0xffff} ) diff --git a/src/pkg/image/color/ycbcr.go b/src/pkg/image/color/ycbcr.go index c79816dd45a..c6b9ba08db3 100644 --- a/src/pkg/image/color/ycbcr.go +++ b/src/pkg/image/color/ycbcr.go @@ -4,8 +4,7 @@ package color -// RGBToYCbCr converts an RGB triple to a Y'CbCr triple. All components lie -// within the range [0, 255]. +// RGBToYCbCr converts an RGB triple to a Y'CbCr triple. func RGBToYCbCr(r, g, b uint8) (uint8, uint8, uint8) { // The JFIF specification says: // Y' = 0.2990*R + 0.5870*G + 0.1140*B @@ -36,8 +35,7 @@ func RGBToYCbCr(r, g, b uint8) (uint8, uint8, uint8) { return uint8(yy), uint8(cb), uint8(cr) } -// YCbCrToRGB converts a Y'CbCr triple to an RGB triple. All components lie -// within the range [0, 255]. +// YCbCrToRGB converts a Y'CbCr triple to an RGB triple. func YCbCrToRGB(y, cb, cr uint8) (uint8, uint8, uint8) { // The JFIF specification says: // R = Y' + 1.40200*(Cr-128) @@ -89,11 +87,13 @@ func (c YCbCr) RGBA() (uint32, uint32, uint32, uint32) { } // YCbCrModel is the Model for Y'CbCr colors. -var YCbCrModel Model = ModelFunc(func(c Color) Color { +var YCbCrModel Model = ModelFunc(modelYCbCr) + +func modelYCbCr(c Color) Color { if _, ok := c.(YCbCr); ok { return c } r, g, b, _ := c.RGBA() y, u, v := RGBToYCbCr(uint8(r>>8), uint8(g>>8), uint8(b>>8)) return YCbCr{y, u, v} -}) +}