Added a fix from the fix from [mapbox/earcut#91](mapbox/earcut#91)

Updated LICENSE to be in-line with Mapbox's ISC requirements

LICENSE

@@ -19,3 +19,19 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+ISC License
+
+Copyright (c) 2016, Mapbox
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.

README.md

@@ -1,6 +1,6 @@
 # dart_earcut
 
-Ear-clipping (earcutting) triangulation algorithm, ported (with minor API differences) from [earcut4j/earcut4j](https://github.com/earcut4j/earcut4j) and [mapbox/earcut](https://github.com/mapbox/earcut).
+Ear-clipping (earcutting) triangulation algorithm, ported (with minor API differences) from [earcut4j/earcut4j](https://github.com/earcut4j/earcut4j) and [mapbox/earcut](https://github.com/mapbox/earcut). Also includes the fix from [mapbox/earcut#91](https://github.com/mapbox/earcut/pull/91).
 
 ## Usage
 

lib/dart_earcut.dart

@@ -46,8 +46,14 @@ abstract final class Earcut {
     final int outerLen =
         hasHoles ? holeIndices[0] * dimensions : polygonVertices.length;
 
-    _Node? outerNode =
-        _linkedList(polygonVertices, 0, outerLen, dimensions, clockwise: true);
+    _Node? outerNode = _linkedList(
+      polygonVertices,
+      0,
+      outerLen,
+      dimensions,
+      null,
+      clockwise: true,
+    );
 
     final triangles = <int>[];
 
@@ -546,11 +552,15 @@ abstract final class Earcut {
   ) {
     final queue = <_Node>[];
 
+    int holeId = 0;
+
     final int len = holeIndices.length;
     for (int i = 0; i < len; i++) {
       final int start = holeIndices[i] * dim;
       final int end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
-      final _Node? list = _linkedList(data, start, end, dim, clockwise: false);
+      holeId = i + 1;
+      final _Node? list =
+          _linkedList(data, start, end, dim, holeId, clockwise: false);
       if (list == list?.next) list?.steiner = true;
       queue.add(_getLeftmost(list!));
     }
@@ -582,8 +592,36 @@ abstract final class Earcut {
     do {
       again = false;
 
-      if (!p.steiner && _equals(p, p.next!) ||
-          _area(p.prev!, p, p.next!) == 0) {
+      final prevHole = p.prev!.holeId;
+      final currentHole = p.holeId;
+      final nextHole = p.next!.holeId;
+
+      var toRemove = false;
+
+      if (!p.steiner) {
+        if (_equals(p, p.next!) || _equals(p.prev!, p)) {
+          toRemove = true;
+        } else if ((prevHole != null || prevHole != 0) ||
+            (nextHole != null || nextHole != 0) ||
+            prevHole == nextHole ||
+            prevHole != currentHole) {
+          // When `p.prev, p & p.next` are collinear,
+          // If `p.prev, p & p.next` are on holes (not outer edge) ,
+          // And `p.prev & p` are on the same hole ,
+          // Then do NOT remove `p` .
+
+          // In other words,
+          // When `p.prev, p & p.next` are collinear,
+          // If `p.prev, p & p.next` are on the outer edge,
+          // Or `p.prev & p` are on different holes ,
+          // Then do REMOVE `p`
+          if (_area(p.prev!, p, p.next!) == 0) {
+            toRemove = true;
+          }
+        }
+      }
+
+      if (toRemove) {
         _removeNode(p);
         p = (end = p.prev)!;
         if (p == p.next) {
@@ -620,6 +658,9 @@ abstract final class Earcut {
     final an = a.next!;
     final bp = b.prev!;
 
+    a2.holeId = a.holeId;
+    b2.holeId = b.holeId;
+
     a.next = b;
     b.prev = a;
 
@@ -760,23 +801,25 @@ abstract final class Earcut {
     List<double> data,
     int start,
     int end,
-    int dim, {
+    int dim,
+    int? holeId, {
     required bool clockwise,
   }) {
     _Node? last;
     if (clockwise == (_signedArea(data, start, end, dim) > 0)) {
       for (int i = start; i < end; i += dim) {
-        last = _insertNode(i, data[i], data[i + 1], last);
+        last = _insertNode(i, data[i], data[i + 1], last)..holeId = holeId;
       }
     } else {
       for (int i = end - dim; i >= start; i -= dim) {
-        last = _insertNode(i, data[i], data[i + 1], last);
+        last = _insertNode(i, data[i], data[i + 1], last)..holeId = holeId;
       }
     }
 
     if (last != null && _equals(last, last.next!)) {
       _removeNode(last);
       last = last.next;
+      last?.holeId = holeId;
     }
 
     return last;
@@ -829,6 +872,7 @@ final class _Node {
   _Node? next;
   _Node? prevZ;
   _Node? nextZ;
+  int? holeId;
 
   _Node(this.i, this.x, this.y)
       : z = 4.9E-324,

pubspec.lock

@@ -5,18 +5,18 @@ packages:
     dependency: transitive
     description:
       name: _fe_analyzer_shared
-      sha256: "0816708f5fbcacca324d811297153fe3c8e047beb5c6752e12292d2974c17045"
+      sha256: eb376e9acf6938204f90eb3b1f00b578640d3188b4c8a8ec054f9f479af8d051
       url: "https://pub.dev"
     source: hosted
-    version: "62.0.0"
+    version: "64.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
-      sha256: "21862995c9932cd082f89d72ae5f5e2c110d1a0204ad06e4ebaee8307b76b834"
+      sha256: "69f54f967773f6c26c7dcb13e93d7ccee8b17a641689da39e878d5cf13b06893"
       url: "https://pub.dev"
     source: hosted
-    version: "6.0.0"
+    version: "6.2.0"
   args:
     dependency: transitive
     description:
@@ -73,14 +73,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.3"
-  dart_internal:
-    dependency: transitive
-    description:
-      name: dart_internal
-      sha256: "689dccc3d5f62affd339534cca548dce12b3a6b32f0f10861569d3025efc0567"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.2.9"
   file:
     dependency: transitive
     description:
@@ -378,4 +370,4 @@ packages:
     source: hosted
     version: "3.1.2"
 sdks:
-  dart: ">=3.0.0 <3.3.0"
+  dart: ">=3.0.0 <4.0.0"