From 0c72ed305790eac315862eed0d23da1203e23b3b Mon Sep 17 00:00:00 2001
From: Stephen White <senorblanco@chromium.org>
Date: Thu, 13 Jun 2019 13:13:13 -0400
Subject: [PATCH] GrTessellator: fix for even/odd fill type and path holes.

When extracting contours for the even/odd fill type, connected holes
in the interior of a shape don't get rendered correctly.

The fix is to extract the subcontours separately from the outer contour.
To do this, we abort contour extraction the first time we re-encounter
the starting vertex.  This causes the hole to be extracted as a
separate contour.

Bug: 908646
Change-Id: I047b77c74605987c40c12a228fd2898c9aa74e55
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220776
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
---
 gm/crbug_908646.cpp       | 29 +++++++++++++++++++++++++++++
 gn/gm.gni                 |  1 +
 src/gpu/GrTessellator.cpp |  5 +++--
 3 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 gm/crbug_908646.cpp

diff --git a/gm/crbug_908646.cpp b/gm/crbug_908646.cpp
new file mode 100644
index 0000000000..843799ec22
--- /dev/null
+++ b/gm/crbug_908646.cpp
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2019 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm/gm.h"
+#include "include/core/SkCanvas.h"
+#include "include/core/SkPaint.h"
+#include "include/core/SkPath.h"
+
+DEF_SIMPLE_GM(crbug_908646, canvas, 300, 300) {
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    SkPath path;
+    path.setFillType(SkPath::kEvenOdd_FillType);
+    path.moveTo(50,  50);
+    path.lineTo(50,  300);
+    path.lineTo(250, 300);
+    path.lineTo(250, 50);
+    path.moveTo(200, 100);
+    path.lineTo(100, 100);
+    path.lineTo(150, 200);
+    path.moveTo(100, 250);
+    path.lineTo(150, 150);
+    path.lineTo(200, 250);
+    canvas->drawPath(path, paint);
+}
diff --git a/gn/gm.gni b/gn/gm.gni
index 5608d5191d..c007bc25a1 100644
--- a/gn/gm.gni
+++ b/gn/gm.gni
@@ -108,6 +108,7 @@ gm_sources = [
   "$_gm/crbug_892988.cpp",
   "$_gm/crbug_899512.cpp",
   "$_gm/crbug_905548.cpp",
+  "$_gm/crbug_908646.cpp",
   "$_gm/crbug_913349.cpp",
   "$_gm/crbug_918512.cpp",
   "$_gm/crbug_938592.cpp",
diff --git a/src/gpu/GrTessellator.cpp b/src/gpu/GrTessellator.cpp
index 2739ae1515..ef1548381e 100644
--- a/src/gpu/GrTessellator.cpp
+++ b/src/gpu/GrTessellator.cpp
@@ -2109,7 +2109,8 @@ void stroke_boundary(EdgeList* boundary, VertexList* innerMesh, VertexList* oute
 void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkArenaAlloc& alloc) {
     LOG("\nextracting boundary\n");
     bool down = apply_fill_type(fillType, e->fWinding);
-    while (e) {
+    Vertex* start = down ? e->fTop : e->fBottom;
+    do {
         e->fWinding = down ? 1 : -1;
         Edge* next;
         e->fLine.normalize();
@@ -2136,7 +2137,7 @@ void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, Sk
         }
         disconnect(e);
         e = next;
-    }
+    } while (e && (down ? e->fTop : e->fBottom) != start);
 }
 
 // Stage 5b: Extract boundaries from mesh, simplify and stroke them into a new mesh.