gpu,op/clip: implement dashed stroked paths

Signed-off-by: Sebastien Binet <s@sbinet.org>

internal/opconst/ops.go

@@ -33,6 +33,7 @@ const (
 	TypeCursor
 	TypePath
 	TypeStroke
+	TypeDash
 )
 
 const (
@@ -61,6 +62,7 @@ const (
 	TypeCursorLen          = 1 + 1
 	TypePathLen            = 1 + 4
 	TypeStrokeLen          = 1 + 4 + 4 + 1 + 1
+	TypeDashLen            = 1 + 4 + 1
 )
 
 func (t OpType) Size() int {
@@ -90,6 +92,7 @@ func (t OpType) Size() int {
 		TypeCursorLen,
 		TypePathLen,
 		TypeStrokeLen,
+		TypeDashLen,
 	}[t-firstOpIndex]
 }
 

internal/rendertest/clip_test.go

@@ -36,6 +36,28 @@ func TestPaintClippedRect(t *testing.T) {
 	})
 }
 
+func TestPaintClippedBorder(t *testing.T) {
+	run(t, func(o *op.Ops) {
+		var dashes clip.Dash
+		dashes.Begin(o)
+		dashes.Phase(1)
+		dashes.Dash(2)
+		dashes.Dash(1)
+
+		clip.Border{
+			Rect:   f32.Rect(25, 25, 60, 60),
+			Width:  4,
+			Dashes: dashes.End(),
+		}.Add(o)
+		paint.FillShape(o, red, clip.Rect(image.Rect(0, 0, 50, 50)).Op())
+	}, func(r result) {
+		r.expect(0, 0, colornames.White)
+		r.expect(25, 25, colornames.Red)
+		r.expect(50, 0, colornames.White)
+		r.expect(10, 50, colornames.White)
+	})
+}
+
 func TestPaintClippedCirle(t *testing.T) {
 	run(t, func(o *op.Ops) {
 		r := float32(10)
@@ -318,6 +340,177 @@ func TestStrokedPathZeroWidth(t *testing.T) {
 	})
 }
 
+func TestDashedPathFlatCapEllipse(t *testing.T) {
+	run(t, func(o *op.Ops) {
+		{
+			stk := op.Push(o)
+			p := newEllipsePath(o)
+
+			var dash clip.Dash
+			dash.Begin(o)
+			dash.Dash(5)
+			dash.Dash(3)
+
+			clip.Stroke{
+				Path: p,
+				Style: clip.StrokeStyle{
+					Width: 10,
+					Cap:   clip.FlatCap,
+					Join:  clip.BevelJoin,
+					Miter: float32(math.Inf(+1)),
+				},
+				Dashes: dash.End(),
+			}.Op().Add(o)
+
+			paint.Fill(
+				o,
+				red,
+			)
+			stk.Pop()
+		}
+		{
+			stk := op.Push(o)
+			p := newEllipsePath(o)
+			clip.Stroke{
+				Path: p,
+				Style: clip.StrokeStyle{
+					Width: 2,
+				},
+			}.Op().Add(o)
+
+			paint.Fill(
+				o,
+				black,
+			)
+			stk.Pop()
+		}
+
+	}, func(r result) {
+		r.expect(0, 0, colornames.White)
+		r.expect(0, 62, colornames.Red)
+		r.expect(0, 65, colornames.Black)
+	})
+}
+
+func TestDashedPathFlatCapZ(t *testing.T) {
+	run(t, func(o *op.Ops) {
+		{
+			stk := op.Push(o)
+			p := newZigZagPath(o)
+			var dash clip.Dash
+			dash.Begin(o)
+			dash.Dash(5)
+			dash.Dash(3)
+
+			clip.Stroke{
+				Path: p,
+				Style: clip.StrokeStyle{
+					Width: 10,
+					Cap:   clip.FlatCap,
+					Join:  clip.BevelJoin,
+					Miter: float32(math.Inf(+1)),
+				},
+				Dashes: dash.End(),
+			}.Op().Add(o)
+			paint.Fill(o, red)
+			stk.Pop()
+		}
+
+		{
+			stk := op.Push(o)
+			p := newZigZagPath(o)
+			clip.Stroke{
+				Path:  p,
+				Style: clip.StrokeStyle{Width: 2},
+			}.Op().Add(o)
+			paint.Fill(o, black)
+			stk.Pop()
+		}
+	}, func(r result) {
+		r.expect(0, 0, colornames.White)
+		r.expect(40, 10, colornames.Black)
+		r.expect(40, 12, colornames.Red)
+		r.expect(46, 12, colornames.White)
+	})
+}
+
+func TestDashedPathFlatCapZNoDash(t *testing.T) {
+	run(t, func(o *op.Ops) {
+		{
+			stk := op.Push(o)
+			p := newZigZagPath(o)
+			var dash clip.Dash
+			dash.Begin(o)
+			dash.Phase(1)
+
+			clip.Stroke{
+				Path: p,
+				Style: clip.StrokeStyle{
+					Width: 10,
+					Cap:   clip.FlatCap,
+					Join:  clip.BevelJoin,
+					Miter: float32(math.Inf(+1)),
+				},
+				Dashes: dash.End(),
+			}.Op().Add(o)
+			paint.Fill(o, red)
+			stk.Pop()
+		}
+		{
+			stk := op.Push(o)
+			clip.Stroke{
+				Path:  newZigZagPath(o),
+				Style: clip.StrokeStyle{Width: 2},
+			}.Op().Add(o)
+			paint.Fill(o, black)
+			stk.Pop()
+		}
+	}, func(r result) {
+		r.expect(0, 0, colornames.White)
+		r.expect(40, 10, colornames.Black)
+		r.expect(40, 12, colornames.Red)
+		r.expect(46, 12, colornames.Red)
+	})
+}
+
+func TestDashedPathFlatCapZNoPath(t *testing.T) {
+	run(t, func(o *op.Ops) {
+		{
+			stk := op.Push(o)
+			var dash clip.Dash
+			dash.Begin(o)
+			dash.Dash(0)
+			clip.Stroke{
+				Path: newZigZagPath(o),
+				Style: clip.StrokeStyle{
+					Width: 10,
+					Cap:   clip.FlatCap,
+					Join:  clip.BevelJoin,
+					Miter: float32(math.Inf(+1)),
+				},
+				Dashes: dash.End(),
+			}.Op().Add(o)
+			paint.Fill(o, red)
+			stk.Pop()
+		}
+		{
+			stk := op.Push(o)
+			p := newZigZagPath(o)
+			clip.Stroke{
+				Path:  p,
+				Style: clip.StrokeStyle{Width: 2},
+			}.Op().Add(o)
+			paint.Fill(o, black)
+			stk.Pop()
+		}
+	}, func(r result) {
+		r.expect(0, 0, colornames.White)
+		r.expect(40, 10, colornames.Black)
+		r.expect(40, 12, colornames.White)
+		r.expect(46, 12, colornames.White)
+	})
+}
+
 func newStrokedPath(o *op.Ops) clip.PathSpec {
 	p := new(clip.Path)
 	p.Begin(o)