Include vendor dependencies

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

@@ -0,0 +1,123 @@
+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}
+}