status-go/vendor/github.com/fogleman/gg/pattern.go

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2022-06-25 07:20:02 +00:00
package gg
import (
"image"
"image/color"
"github.com/golang/freetype/raster"
)
type RepeatOp int
const (
RepeatBoth RepeatOp = iota
RepeatX
RepeatY
RepeatNone
)
type Pattern interface {
ColorAt(x, y int) color.Color
}
// Solid Pattern
type solidPattern struct {
color color.Color
}
func (p *solidPattern) ColorAt(x, y int) color.Color {
return p.color
}
func NewSolidPattern(color color.Color) Pattern {
return &solidPattern{color: color}
}
// Surface Pattern
type surfacePattern struct {
im image.Image
op RepeatOp
}
func (p *surfacePattern) ColorAt(x, y int) color.Color {
b := p.im.Bounds()
switch p.op {
case RepeatX:
if y >= b.Dy() {
return color.Transparent
}
case RepeatY:
if x >= b.Dx() {
return color.Transparent
}
case RepeatNone:
if x >= b.Dx() || y >= b.Dy() {
return color.Transparent
}
}
x = x%b.Dx() + b.Min.X
y = y%b.Dy() + b.Min.Y
return p.im.At(x, y)
}
func NewSurfacePattern(im image.Image, op RepeatOp) Pattern {
return &surfacePattern{im: im, op: op}
}
type patternPainter struct {
im *image.RGBA
mask *image.Alpha
p Pattern
}
// Paint satisfies the Painter interface.
func (r *patternPainter) Paint(ss []raster.Span, done bool) {
b := r.im.Bounds()
for _, s := range ss {
if s.Y < b.Min.Y {
continue
}
if s.Y >= b.Max.Y {
return
}
if s.X0 < b.Min.X {
s.X0 = b.Min.X
}
if s.X1 > b.Max.X {
s.X1 = b.Max.X
}
if s.X0 >= s.X1 {
continue
}
const m = 1<<16 - 1
y := s.Y - r.im.Rect.Min.Y
x0 := s.X0 - r.im.Rect.Min.X
// RGBAPainter.Paint() in $GOPATH/src/github.com/golang/freetype/raster/paint.go
i0 := (s.Y-r.im.Rect.Min.Y)*r.im.Stride + (s.X0-r.im.Rect.Min.X)*4
i1 := i0 + (s.X1-s.X0)*4
for i, x := i0, x0; i < i1; i, x = i+4, x+1 {
ma := s.Alpha
if r.mask != nil {
ma = ma * uint32(r.mask.AlphaAt(x, y).A) / 255
if ma == 0 {
continue
}
}
c := r.p.ColorAt(x, y)
cr, cg, cb, ca := c.RGBA()
dr := uint32(r.im.Pix[i+0])
dg := uint32(r.im.Pix[i+1])
db := uint32(r.im.Pix[i+2])
da := uint32(r.im.Pix[i+3])
a := (m - (ca * ma / m)) * 0x101
r.im.Pix[i+0] = uint8((dr*a + cr*ma) / m >> 8)
r.im.Pix[i+1] = uint8((dg*a + cg*ma) / m >> 8)
r.im.Pix[i+2] = uint8((db*a + cb*ma) / m >> 8)
r.im.Pix[i+3] = uint8((da*a + ca*ma) / m >> 8)
}
}
}
func newPatternPainter(im *image.RGBA, mask *image.Alpha, p Pattern) *patternPainter {
return &patternPainter{im, mask, p}
}