Add fill leak checker (use -d:pixieLeakCheck).

src/pixie/paths.nim

@@ -1164,6 +1164,10 @@ template computeCoverages(
 
       count += winding
 
+    when defined(pixieLeakCheck):
+      if prevAt != size.x and count != 0:
+        echo "Leak detected: ", count, " @ ", prevAt, " ", y
+
 proc fillShapes(
   image: Image,
   shapes: seq[seq[Vec2]],
@@ -1359,7 +1363,7 @@ proc strokeShapes(
   miterLimit: float32,
   dashes: seq[float32]
 ): seq[seq[Vec2]] =
-  if strokeWidth == 0:
+  if strokeWidth <= 0:
     return
 
   let miterAngleLimit = miterLimitToAngle(miterLimit)

tests/fuzz_leaks.nim

@@ -0,0 +1,30 @@
+import pixie, random
+
+when not defined(pixieLeakCheck):
+  quit("Requires -d:pixieLeakCheck")
+
+randomize()
+
+for i in 0 ..< 100_000:
+
+  let image = newImage(400, 400)
+  image.fill(rgba(255, 255, 255, 255))
+
+  let ctx = newContext(image)
+  ctx.translate(200, 200)
+  ctx.scale(vec2(rand(0.1 .. 1.2), rand(0.1 .. 1.2)))
+  ctx.rotate(rand(0.0 .. 2*PI))
+
+  ctx.strokeStyle = "#000000"
+  ctx.lineCap = sample([lcRound, lcButt, lcSquare])
+  ctx.lineJoin = sample([ljMiter, ljRound, ljBevel])
+  ctx.miterLimit = 2
+  ctx.lineWidth = rand(0.1 .. 20.0)
+
+  ctx.moveTo(rand(-100 .. 100).float32, rand(-100 .. 100).float32)
+  for i in 0 ..< rand(0 .. 100):
+    ctx.lineTo(rand(-100 .. 100).float32, rand(-100 .. 100).float32)
+  ctx.stroke()
+
+  # image.writeFile("tests/fuzz_leaks.png")
+  # break

tests/fuzz_leaks2.nim

@@ -0,0 +1,36 @@
+import pixie, random, os
+
+when not defined(pixieLeakCheck):
+  quit("Requires -d:pixieLeakCheck")
+
+randomize()
+
+for i in 0 ..< 100_000:
+  let image = newImage(400, 400)
+  image.fill(rgba(255, 255, 255, 255))
+
+  let ctx = newContext(image)
+
+  ctx.translate(200, 200)
+  ctx.scale(vec2(rand(0.1 .. 1.7), rand(0.1 .. 1.7)))
+  ctx.rotate(rand(0.0 .. 2*PI))
+
+  ctx.strokeStyle = "#000000"
+  ctx.lineCap = sample([lcRound, lcButt, lcSquare])
+  ctx.lineJoin = sample([ljMiter, ljRound, ljBevel])
+  ctx.lineWidth = rand(0.1 .. 1.0)
+
+  var first = true
+  var number = rand(2 .. 100)
+  for a in 0 .. number:
+    let th = a.float32 / number.float32 * PI
+    let pos = vec2(sin(th) * 100, cos(th) * 100)
+    if first:
+      ctx.moveTo(pos)
+      first = false
+    else:
+      ctx.lineTo(pos)
+  ctx.stroke()
+
+  # image.writeFile("tests/fuzz_leaks2.png")
+  # break

tests/fuzz_leaks3.nim

@@ -0,0 +1,14 @@
+import pixie, random, pixie/fileformats/svg
+
+when not defined(pixieLeakCheck):
+  quit("Requires -d:pixieLeakCheck")
+
+randomize()
+
+let data = readFile("tests/images/svg/Ghostscript_Tiger.svg")
+
+for i in 0 ..< 100_000:
+  var image = decodeSvg(data, rand(300 .. 1800),  rand(30 .. 1800))
+
+  # image.writeFile("tests/fuzz_leaks3.png")
+  # break