op/clip: automatically close Path in Outlines

Unclosed path segments in Path will be automatically
closed by a line.

Fixes: https://todo.sr.ht/~eliasnaur/gio/320
Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

gpu/compute.go

@@ -1186,12 +1186,19 @@ func min(p1, p2 f32.Point) f32.Point {
 	return p
 }
 
-func (enc *encoder) encodePath(verts []byte) {
-	for len(verts) >= scene.CommandSize+4 {
+func (enc *encoder) encodePath(verts []byte, fillMode int) {
+	for ; len(verts) >= scene.CommandSize+4; verts = verts[scene.CommandSize+4:] {
 		cmd := ops.DecodeCommand(verts[4:])
+		if cmd.Op() == scene.OpGap {
+			if fillMode != scene.FillModeNonzero {
+				// Skip gaps in strokes.
+				continue
+			}
+			// Replace them by a straight line in outlines.
+			cmd = scene.Line(scene.DecodeGap(cmd))
+		}
 		enc.scene = append(enc.scene, cmd)
 		enc.npathseg++
-		verts = verts[scene.CommandSize+4:]
 	}
 }
 
@@ -2109,7 +2116,7 @@ func encodeOp(viewport image.Point, absOff image.Point, enc *encoder, texOps []t
 		if len(cl.path) == 0 {
 			enc.rect(cl.state.bounds)
 		} else {
-			enc.encodePath(cl.path)
+			enc.encodePath(cl.path, fillMode)
 		}
 		if i != 0 {
 			enc.beginClip(cl.union.Add(absOfff))

gpu/gpu.go

@@ -1344,6 +1344,12 @@ func decodeToOutlineQuads(qs *quadSplitter, tr f32.Affine2D, pathData []byte) {
 			q.Ctrl = q.From.Add(q.To).Mul(.5)
 			q = q.Transform(tr)
 			qs.splitAndEncode(q)
+		case scene.OpGap:
+			var q stroke.QuadSegment
+			q.From, q.To = scene.DecodeGap(cmd)
+			q.Ctrl = q.From.Add(q.To).Mul(.5)
+			q = q.Transform(tr)
+			qs.splitAndEncode(q)
 		case scene.OpQuad:
 			var q stroke.QuadSegment
 			q.From, q.Ctrl, q.To = scene.DecodeQuad(cmd)

gpu/internal/rendertest/render_test.go

@@ -357,6 +357,60 @@ func TestImageRGBA(t *testing.T) {
 	})
 }
 
+func TestGapsInPath(t *testing.T) {
+	ops := new(op.Ops)
+	var p clip.Path
+	p.Begin(ops)
+	// Unclosed square 1
+	p.MoveTo(f32.Point{X: 10})
+	p.LineTo(f32.Point{X: 40})
+	p.LineTo(f32.Point{X: 40, Y: 30})
+	p.LineTo(f32.Point{X: 10, Y: 30})
+
+	// Unclosed square 2
+	p.MoveTo(f32.Point{X: 50})
+	p.LineTo(f32.Point{X: 80})
+	p.LineTo(f32.Point{X: 80, Y: 30})
+	p.LineTo(f32.Point{X: 50, Y: 30})
+
+	spec := p.End()
+
+	t.Run("Stroke", func(t *testing.T) {
+		run(t,
+			func(ops *op.Ops) {
+				stack := clip.Stroke{
+					Path:  spec,
+					Width: 2,
+				}.Op().Push(ops)
+				paint.ColorOp{Color: color.NRGBA{R: 255, A: 255}}.Add(ops)
+				paint.PaintOp{}.Add(ops)
+				stack.Pop()
+			},
+			func(r result) {
+				r.expect(10, 20, color.RGBA{})
+				r.expect(50, 20, color.RGBA{})
+			},
+		)
+	})
+
+	t.Run("Outline", func(t *testing.T) {
+		run(t,
+			func(ops *op.Ops) {
+				stack := clip.Outline{Path: spec}.Op().Push(ops)
+				paint.ColorOp{Color: color.NRGBA{R: 255, A: 255}}.Add(ops)
+				paint.PaintOp{}.Add(ops)
+				stack.Pop()
+			},
+			func(r result) {
+				r.expect(10, 20, colornames.Red)
+				r.expect(20, 20, colornames.Red)
+				r.expect(50, 20, colornames.Red)
+				r.expect(60, 20, colornames.Red)
+			},
+		)
+	})
+}
+
 // lerp calculates linear interpolation with color b and p.
 func lerp(a, b f32color.RGBA, p float32) f32color.RGBA {
 	return f32color.RGBA{

gpu/internal/rendertest/util_test.go

@@ -11,6 +11,7 @@ import (
 	"image/draw"
 	"image/png"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strconv"
 	"testing"
@@ -143,11 +144,20 @@ func multiRun(t *testing.T, frames ...frameT) {
 
 func verifyRef(t *testing.T, img *image.RGBA, frame int) (ok bool) {
 	// ensure identical to ref data
-	path := filepath.Join("refs", t.Name()+".png")
-	if frame != 0 {
-		path = filepath.Join("refs", t.Name()+"_"+strconv.Itoa(frame)+".png")
+	var path string
+	if frame == 0 {
+		path = t.Name()
+	} else {
+		path = t.Name() + "_" + strconv.Itoa(frame)
 	}
+	path = filepath.Join("refs", path+".png")
 	if *dumpImages {
+		if err := os.MkdirAll(filepath.Dir(path), 0766); err != nil {
+			if !os.IsExist(err) {
+				t.Error(err)
+				return
+			}
+		}
 		saveImage(t, path, img)
 		return true
 	}