3 files changed, 27 insertions(+), 5 deletions(-)

M stroke/clip_test.go
M stroke/refs/TestStrokedPathArc.png
M stroke/stroke.go

@@ 333,11 333,15 @@ func TestStrokedPathArc(t *testing.T) {
 			Segments: []Segment{
 				MoveTo(f32.Pt(0, 65)),
 				LineTo(f32.Pt(20, 65)),
-				ArcTo(f32.Pt(70, 65), +math.Pi/3),
+				ArcTo(f32.Pt(70, 65), +math.Pi/6),
 				LineTo(f32.Pt(70, 65)),
 				LineTo(f32.Pt(20, 65)),
-				ArcTo(f32.Pt(70, 65), -math.Pi/2),
+				ArcTo(f32.Pt(70, 65), -math.Pi/6),
 				LineTo(f32.Pt(70, 65)),
+				LineTo(f32.Pt(70, 115)),
+				ArcTo(f32.Pt(70, 65), -7*math.Pi/6),
+				LineTo(f32.Pt(70, 65)),
+				LineTo(f32.Pt(70, 15)),
 			},
 		}
 		cl := Stroke{


@@ 352,6 356,7 @@ func TestStrokedPathArc(t *testing.T) {
 		r.expect(0, 0, transparent)
 		r.expect(70, 65, colornames.Red)
 		r.expect(35, 65, colornames.Red)
+		r.expect(120, 65, colornames.Red)
 	})
 }
 

@@ 4,6 4,8 @@
 package stroke
 
 import (
+	"math"
+
 	"gioui.org/f32"
 	"gioui.org/op"
 	"gioui.org/op/clip"


@@ 163,9 165,20 @@ func (s Stroke) Op(ops *op.Ops) clip.Op {
 			contour = append(contour, stroke.Segment{stroke.Point(pen), stroke.Point(seg.args[0]), stroke.Point(seg.args[1]), stroke.Point(seg.args[2])})
 			pen = seg.args[2]
 		case segOpArcTo:
-			out := stroke.ArcSegment(stroke.Point(pen), stroke.Point(seg.args[0]), seg.args[1].X)
-			contour = append(contour, out)
-			pen = f32.Point(out.End)
+			var (
+				start  = stroke.Point(pen)
+				center = stroke.Point(seg.args[0])
+				angle  = seg.args[1].X
+			)
+			switch {
+			case absF32(angle) > math.Pi:
+				contour = stroke.AppendArc(contour, start, center, angle)
+				pen = f32.Point(contour[len(contour)-1].End)
+			default:
+				out := stroke.ArcSegment(start, center, angle)
+				contour = append(contour, out)
+				pen = f32.Point(out.End)
+			}
 		}
 	}
 	if len(contour) > 0 {


@@ 219,3 232,7 @@ func (s Stroke) Op(ops *op.Ops) clip.Op {
 
 	return clip.Outline{Path: outline.End()}.Op()
 }
+
+func absF32(x float32) float32 {
+	return math.Float32frombits(math.Float32bits(x) &^ (1 << 31))
+}