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// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package affine
import (
"image/color"
"math"
)
// ColorMDim is a dimension of a ColorM.
const ColorMDim = 5
var (
colorMIdentityBody = []float32{
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1,
}
colorMIdentityTranslate = []float32{
0, 0, 0, 0,
}
)
// A ColorM represents a matrix to transform coloring when rendering an image.
//
// A ColorM is applied to the source alpha color
// while an Image's pixels' format is alpha premultiplied.
// Before applying a matrix, a color is un-multiplied, and after applying the matrix,
// the color is multiplied again.
//
// The nil and initial value is identity.
type ColorM struct {
// When elements is nil, this matrix is identity.
// elements are immutable and a new array must be created when updating.
body []float32
translate []float32
}
func clamp(x float32) float32 {
if x > 1 {
return 1
}
if x < 0 {
return 0
}
return x
}
func (c *ColorM) isInited() bool {
return c != nil && (c.body != nil || c.translate != nil)
}
func (c *ColorM) ScaleOnly() bool {
if c == nil {
return true
}
if c.body != nil {
if c.body[1] != 0 {
return false
}
if c.body[2] != 0 {
return false
}
if c.body[3] != 0 {
return false
}
if c.body[4] != 0 {
return false
}
if c.body[6] != 0 {
return false
}
if c.body[7] != 0 {
return false
}
if c.body[8] != 0 {
return false
}
if c.body[9] != 0 {
return false
}
if c.body[11] != 0 {
return false
}
if c.body[12] != 0 {
return false
}
if c.body[13] != 0 {
return false
}
if c.body[14] != 0 {
return false
}
}
if c.translate != nil {
for _, e := range c.translate {
if e != 0 {
return false
}
}
}
return true
}
func (c *ColorM) Apply(clr color.Color) color.Color {
if !c.isInited() {
return clr
}
r, g, b, a := clr.RGBA()
rf, gf, bf, af := float32(0.0), float32(0.0), float32(0.0), float32(0.0)
// Unmultiply alpha
if a > 0 {
rf = float32(r) / float32(a)
gf = float32(g) / float32(a)
bf = float32(b) / float32(a)
af = float32(a) / 0xffff
}
eb := c.body
if eb == nil {
eb = colorMIdentityBody
}
et := c.translate
if et == nil {
et = colorMIdentityTranslate
}
rf2 := eb[0]*rf + eb[4]*gf + eb[8]*bf + eb[12]*af + et[0]
gf2 := eb[1]*rf + eb[5]*gf + eb[9]*bf + eb[13]*af + et[1]
bf2 := eb[2]*rf + eb[6]*gf + eb[10]*bf + eb[14]*af + et[2]
af2 := eb[3]*rf + eb[7]*gf + eb[11]*bf + eb[15]*af + et[3]
rf2 = clamp(rf2)
gf2 = clamp(gf2)
bf2 = clamp(bf2)
af2 = clamp(af2)
return color.NRGBA64{
R: uint16(rf2 * 0xffff),
G: uint16(gf2 * 0xffff),
B: uint16(bf2 * 0xffff),
A: uint16(af2 * 0xffff),
}
}
func (c *ColorM) UnsafeElements() ([]float32, []float32) {
if !c.isInited() {
return colorMIdentityBody, colorMIdentityTranslate
}
eb := c.body
if eb == nil {
eb = colorMIdentityBody
}
et := c.translate
if et == nil {
et = colorMIdentityTranslate
}
return eb, et
}
// SetElement sets an element at (i, j).
func (c *ColorM) SetElement(i, j int, element float32) *ColorM {
newC := &ColorM{
body: make([]float32, 16),
translate: make([]float32, 4),
}
copy(newC.body, colorMIdentityBody)
copy(newC.translate, colorMIdentityTranslate)
if c.isInited() {
if c.body != nil {
copy(newC.body, c.body)
}
if c.translate != nil {
copy(newC.translate, c.translate)
}
}
if j < (ColorMDim - 1) {
newC.body[i+j*(ColorMDim-1)] = element
} else {
newC.translate[i] = element
}
return newC
}
func (c *ColorM) Equals(other *ColorM) bool {
if !c.isInited() && !other.isInited() {
return true
}
lhsb := colorMIdentityBody
lhst := colorMIdentityTranslate
rhsb := colorMIdentityBody
rhst := colorMIdentityTranslate
if other.isInited() {
if other.body != nil {
lhsb = other.body
}
if other.translate != nil {
lhst = other.translate
}
}
if c.isInited() {
if c.body != nil {
rhsb = c.body
}
if c.translate != nil {
rhst = c.translate
}
}
if &lhsb == &rhsb && &lhst == &rhst {
return true
}
for i := range lhsb {
if lhsb[i] != rhsb[i] {
return false
}
}
for i := range lhst {
if lhst[i] != rhst[i] {
return false
}
}
return true
}
// Concat multiplies a color matrix with the other color matrix.
// This is same as muptiplying the matrix other and the matrix c in this order.
func (c *ColorM) Concat(other *ColorM) *ColorM {
if !c.isInited() {
return other
}
if !other.isInited() {
return c
}
lhsb := colorMIdentityBody
lhst := colorMIdentityTranslate
rhsb := colorMIdentityBody
rhst := colorMIdentityTranslate
if other.isInited() {
if other.body != nil {
lhsb = other.body
}
if other.translate != nil {
lhst = other.translate
}
}
if c.isInited() {
if c.body != nil {
rhsb = c.body
}
if c.translate != nil {
rhst = c.translate
}
}
return &ColorM{
// TODO: This is a temporary hack to calculate multiply of transposed matrices.
// Fix mulSquare implmentation and swap the arguments.
body: mulSquare(rhsb, lhsb, ColorMDim-1),
translate: []float32{
lhsb[0]*rhst[0] + lhsb[4]*rhst[1] + lhsb[8]*rhst[2] + lhsb[12]*rhst[3] + lhst[0],
lhsb[1]*rhst[0] + lhsb[5]*rhst[1] + lhsb[9]*rhst[2] + lhsb[13]*rhst[3] + lhst[1],
lhsb[2]*rhst[0] + lhsb[6]*rhst[1] + lhsb[10]*rhst[2] + lhsb[14]*rhst[3] + lhst[2],
lhsb[3]*rhst[0] + lhsb[7]*rhst[1] + lhsb[11]*rhst[2] + lhsb[15]*rhst[3] + lhst[3],
},
}
}
// Add is deprecated.
func (c *ColorM) Add(other *ColorM) *ColorM {
lhsb := colorMIdentityBody
lhst := colorMIdentityTranslate
rhsb := colorMIdentityBody
rhst := colorMIdentityTranslate
if other.isInited() {
if other.body != nil {
lhsb = other.body
}
if other.translate != nil {
lhst = other.translate
}
}
if c.isInited() {
if c.body != nil {
rhsb = c.body
}
if c.translate != nil {
rhst = c.translate
}
}
newC := &ColorM{
body: make([]float32, 16),
translate: make([]float32, 4),
}
for i := range lhsb {
newC.body[i] = lhsb[i] + rhsb[i]
}
for i := range lhst {
newC.translate[i] = lhst[i] + rhst[i]
}
return newC
}
// Scale scales the matrix by (r, g, b, a).
func (c *ColorM) Scale(r, g, b, a float32) *ColorM {
if !c.isInited() {
return &ColorM{
body: []float32{
r, 0, 0, 0,
0, g, 0, 0,
0, 0, b, 0,
0, 0, 0, a,
},
}
}
eb := make([]float32, len(colorMIdentityBody))
if c.body != nil {
copy(eb, c.body)
for i := 0; i < ColorMDim-1; i++ {
eb[i*(ColorMDim-1)] *= r
eb[i*(ColorMDim-1)+1] *= g
eb[i*(ColorMDim-1)+2] *= b
eb[i*(ColorMDim-1)+3] *= a
}
} else {
eb[0] = r
eb[5] = g
eb[10] = b
eb[15] = a
}
et := make([]float32, len(colorMIdentityTranslate))
if c.translate != nil {
et[0] = c.translate[0] * r
et[1] = c.translate[1] * g
et[2] = c.translate[2] * b
et[3] = c.translate[3] * a
}
return &ColorM{
body: eb,
translate: et,
}
}
// Translate translates the matrix by (r, g, b, a).
func (c *ColorM) Translate(r, g, b, a float32) *ColorM {
if !c.isInited() {
return &ColorM{
translate: []float32{r, g, b, a},
}
}
es := make([]float32, len(colorMIdentityTranslate))
if c.translate != nil {
copy(es, c.translate)
}
es[0] += r
es[1] += g
es[2] += b
es[3] += a
return &ColorM{
body: c.body,
translate: es,
}
}
var (
// The YCbCr value ranges are:
// Y: [ 0 - 1 ]
// Cb: [-0.5 - 0.5]
// Cr: [-0.5 - 0.5]
rgbToYCbCr = &ColorM{
body: []float32{
0.2990, -0.1687, 0.5000, 0,
0.5870, -0.3313, -0.4187, 0,
0.1140, 0.5000, -0.0813, 0,
0, 0, 0, 1,
},
}
yCbCrToRgb = &ColorM{
body: []float32{
1, 1, 1, 0,
0, -0.34414, 1.77200, 0,
1.40200, -0.71414, 0, 0,
0, 0, 0, 1,
},
}
)
// ChangeHSV changes HSV (Hue-Saturation-Value) elements.
// hueTheta is a radian value to ratate hue.
// saturationScale is a value to scale saturation.
// valueScale is a value to scale value (a.k.a. brightness).
//
// This conversion uses RGB to/from YCrCb conversion.
func (c *ColorM) ChangeHSV(hueTheta float64, saturationScale float32, valueScale float32) *ColorM {
sin, cos := math.Sincos(hueTheta)
s32, c32 := float32(sin), float32(cos)
c = c.Concat(rgbToYCbCr)
c = c.Concat(&ColorM{
body: []float32{
1, 0, 0, 0,
0, c32, s32, 0,
0, -s32, c32, 0,
0, 0, 0, 1,
},
})
s := saturationScale
v := valueScale
c = c.Scale(v, s*v, s*v, 1)
c = c.Concat(yCbCrToRgb)
return c
}
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