p5: better handling of closed paths

Detect shapes that are expected to be closed paths and properly close
the Gio path.
This fixes not quite closed paths because of float32 rounding errors.

Fixes #63.

Signed-off-by: Sebastien Binet <[email protected]>

proc_test.go

@@ -356,3 +356,27 @@ func TestFrameCount_Loop(t *testing.T) {
 		t.Fatalf("should be looping")
 	}
 }
+
+func TestIssue63(t *testing.T) {
+	const (
+		w = 500
+		h = 500
+	)
+	proc := newTestProc(t, w, h,
+		func(p5 *Proc) {
+			p5.Canvas(w, h)
+			p5.Background(color.Gray{Y: 220})
+		},
+		func(p5 *Proc) {
+			p5.StrokeWidth(2)
+			p5.Fill(color.RGBA{R: 255, A: 208})
+			p5.Rect(382.732615, 14.503678, 52, 73)
+
+			p5.Fill(color.RGBA{B: 255, A: 208})
+			p5.Rect(200, 200, 50, 100)
+		},
+		"testdata/issue-063.png",
+		imgDelta,
+	)
+	proc.Run(t)
+}

shapes.go

@@ -289,13 +289,22 @@ func (p *Proc) poly(ps ...f32.Point) {
 		return
 	}
 
+	doClose := false
+	if len(ps) > 1 && ps[0] == ps[len(ps)-1] {
+		doClose = true
+		ps = ps[:len(ps)-1]
+	}
+
 	path := func(o *op.Ops) clip.PathSpec {
 		var path clip.Path
 		path.Begin(o)
 		path.Move(ps[0])
 		for _, p := range ps[1:] {
 			path.Line(p.Sub(path.Pos()))
 		}
+		if doClose {
+			path.Close()
+		}
 		return path.End()
 	}