migrated module to git.milar.in

Add conic gradient

README.md

@@ -14,7 +14,8 @@ Alternatively, you may use gopkg.in to grab a specific major-version:
 
 ## Documentation
 
-https://godoc.org/github.com/fogleman/gg
+- godoc: https://godoc.org/github.com/fogleman/gg
+- pkg.go.dev: https://pkg.go.dev/github.com/fogleman/gg?tab=doc
 
 ## Hello, Circle!
 
@@ -127,7 +128,7 @@ SetFillRule(fillRule FillRule)
 
 ## Gradients & Patterns
 
-`gg` supports linear and radial gradients and surface patterns. You can also implement your own patterns.
+`gg` supports linear, radial and conic gradients and surface patterns. You can also implement your own patterns.
 
 ```go
 SetFillStyle(pattern Pattern)
@@ -135,6 +136,7 @@ SetStrokeStyle(pattern Pattern)
 NewSolidPattern(color color.Color)
 NewLinearGradient(x0, y0, x1, y1 float64)
 NewRadialGradient(x0, y0, r0, x1, y1, r1 float64)
+NewConicGradient(cx, cy, deg float64)
 NewSurfacePattern(im image.Image, op RepeatOp)
 ```
 

context.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"image"
 	"image/color"
+	"image/jpeg"
 	"image/png"
 	"io"
 	"math"
@@ -140,11 +141,23 @@ func (dc *Context) SavePNG(path string) error {
 	return SavePNG(path, dc.im)
 }
 
+// SaveJPG encodes the image as a JPG and writes it to disk.
+func (dc *Context) SaveJPG(path string, quality int) error {
+	return SaveJPG(path, dc.im, quality)
+}
+
 // EncodePNG encodes the image as a PNG and writes it to the provided io.Writer.
 func (dc *Context) EncodePNG(w io.Writer) error {
 	return png.Encode(w, dc.im)
 }
 
+// EncodeJPG encodes the image as a JPG and writes it to the provided io.Writer
+// in JPEG 4:2:0 baseline format with the given options.
+// Default parameters are used if a nil *jpeg.Options is passed.
+func (dc *Context) EncodeJPG(w io.Writer, o *jpeg.Options) error {
+	return jpeg.Encode(w, dc.im, o)
+}
+
 // SetDash sets the current dash pattern to use. Call with zero arguments to
 // disable dashes. The values specify the lengths of each dash, with
 // alternating on and off lengths.
@@ -405,6 +418,7 @@ func (dc *Context) stroke(painter raster.Painter) {
 	r := dc.rasterizer
 	r.UseNonZeroWinding = true
 	r.Clear()
+	r.Dx, r.Dy = dc.im.Bounds().Min.X, dc.im.Bounds().Min.Y
 	r.AddStroke(path, fix(dc.lineWidth), dc.capper(), dc.joiner())
 	r.Rasterize(painter)
 }
@@ -419,6 +433,7 @@ func (dc *Context) fill(painter raster.Painter) {
 	r := dc.rasterizer
 	r.UseNonZeroWinding = dc.fillRule == FillRuleWinding
 	r.Clear()
+	r.Dx, r.Dy = dc.im.Bounds().Min.X, dc.im.Bounds().Min.Y
 	r.AddPath(path)
 	r.Rasterize(painter)
 }
@@ -741,7 +756,7 @@ func (dc *Context) DrawStringAnchored(s string, x, y, ax, ay float64) {
 	x -= ax * w
 	y += ay * h
 	if dc.mask == nil {
-		dc.drawString(dc.im, s, x, y)
+		dc.drawString(dc.im, s, x+float64(dc.im.Bounds().Min.X), y+float64(dc.im.Bounds().Min.Y))
 	} else {
 		im := image.NewRGBA(image.Rect(0, 0, dc.width, dc.height))
 		dc.drawString(im, s, x, y)
@@ -844,13 +859,13 @@ func (dc *Context) ScaleAbout(sx, sy, x, y float64) {
 	dc.Translate(-x, -y)
 }
 
-// Rotate updates the current matrix with a clockwise rotation.
+// Rotate updates the current matrix with a anticlockwise rotation.
 // Rotation occurs about the origin. Angle is specified in radians.
 func (dc *Context) Rotate(angle float64) {
 	dc.matrix = dc.matrix.Rotate(angle)
 }
 
-// RotateAbout updates the current matrix with a clockwise rotation.
+// RotateAbout updates the current matrix with a anticlockwise rotation.
 // Rotation occurs about the specified point. Angle is specified in radians.
 func (dc *Context) RotateAbout(angle, x, y float64) {
 	dc.Translate(x, y)

context_test.go

@@ -191,7 +191,7 @@ func TestPushPop(t *testing.T) {
 		dc.Pop()
 	}
 	saveImage(dc, "TestPushPop")
-	checkHash(t, dc, "e0d6724eb72033577811a55f7a642f6a")
+	checkHash(t, dc, "31e908ee1c2ea180da98fd5681a89d05")
 }
 
 func TestDrawStringWrapped(t *testing.T) {

examples/gradient-conic.go

@@ -0,0 +1,38 @@
+// +build ignore
+
+package main
+
+import (
+	"image/color"
+
+	"github.com/fogleman/gg"
+)
+
+func main() {
+	dc := gg.NewContext(400, 400)
+
+	grad1 := gg.NewConicGradient(200, 200, 0)
+	grad1.AddColorStop(0.0, color.Black)
+	grad1.AddColorStop(0.5, color.RGBA{255, 215, 0, 255})
+	grad1.AddColorStop(1.0, color.RGBA{255, 0, 0, 255})
+
+	grad2 := gg.NewConicGradient(200, 200, 90)
+	grad2.AddColorStop(0.00, color.RGBA{255, 0, 0, 255})
+	grad2.AddColorStop(0.16, color.RGBA{255, 255, 0, 255})
+	grad2.AddColorStop(0.33, color.RGBA{0, 255, 0, 255})
+	grad2.AddColorStop(0.50, color.RGBA{0, 255, 255, 255})
+	grad2.AddColorStop(0.66, color.RGBA{0, 0, 255, 255})
+	grad2.AddColorStop(0.83, color.RGBA{255, 0, 255, 255})
+	grad2.AddColorStop(1.00, color.RGBA{255, 0, 0, 255})
+
+	dc.SetStrokeStyle(grad1)
+	dc.SetLineWidth(20)
+	dc.DrawCircle(200, 200, 180)
+	dc.Stroke()
+
+	dc.SetFillStyle(grad2)
+	dc.DrawCircle(200, 200, 150)
+	dc.Fill()
+
+	dc.SavePNG("gradient-conic.png")
+}

go.mod

@@ -0,0 +1,9 @@
+module git.milar.in/milarin/gg
+
+go 1.18
+
+require (
+	github.com/fogleman/gg v1.3.0
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
+	golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9
+)

go.sum

@@ -0,0 +1,8 @@
+github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
+github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9 h1:LRtI4W37N+KFebI/qV0OFiLUv4GLOWeEW5hn/KEJvxE=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

gradient.go

@@ -164,6 +164,52 @@ func NewRadialGradient(x0, y0, r0, x1, y1, r1 float64) Gradient {
 	return g
 }
 
+// Conic Gradient
+type conicGradient struct {
+	cx, cy   float64
+	rotation float64
+	stops    stops
+}
+
+func (g *conicGradient) ColorAt(x, y int) color.Color {
+	if len(g.stops) == 0 {
+		return color.Transparent
+	}
+	a := math.Atan2(float64(y)-g.cy, float64(x)-g.cx)
+	t := norm(a, -math.Pi, math.Pi) - g.rotation
+	if t < 0 {
+		t += 1
+	}
+	return getColor(t, g.stops)
+}
+
+func (g *conicGradient) AddColorStop(offset float64, color color.Color) {
+	g.stops = append(g.stops, stop{pos: offset, color: color})
+	sort.Sort(g.stops)
+}
+
+func NewConicGradient(cx, cy, deg float64) Gradient {
+	g := &conicGradient{
+		cx:       cx,
+		cy:       cy,
+		rotation: normalizeAngle(deg) / 360,
+	}
+	return g
+}
+
+func normalizeAngle(t float64) float64 {
+	t = math.Mod(t, 360)
+	if t < 0 {
+		t += 360
+	}
+	return t
+}
+
+// Map value which is in range [a..b] to range [0..1]
+func norm(value, a, b float64) float64 {
+	return (value - a) * (1.0 / (b - a))
+}
+
 func getColor(pos float64, stops stops) color.Color {
 	if pos <= 0.0 || len(stops) == 1 {
 		return stops[0].color

util.go

@@ -109,7 +109,7 @@ func fixp(x, y float64) fixed.Point26_6 {
 }
 
 func fix(x float64) fixed.Int26_6 {
-	return fixed.Int26_6(x * 64)
+	return fixed.Int26_6(math.Round(x * 64))
 }
 
 func unfix(x fixed.Int26_6) float64 {