fix zig-zag decoding

To make bitwise operations platform independent the [docs](https://dart.dev/guides/language/numbers#what-should-you-do) recommend coercing to signed 32 bit integers. Fixes #7
greensopinion · Jul 28, 2022 · 48ea150 · 48ea150
1 parent 0c8706b
commit 48ea150
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diff --git a/lib/src/model/geometry_decoding.dart b/lib/src/model/geometry_decoding.dart
@@ -13,7 +13,7 @@ int _decodeCommand(int command) => command & 0x7;
 int _decodeCommandLength(int command) => command >> 3;
 
 @pragma('vm:prefer-inline')
-int _decodeZigZag(int value) => (value >> 1) ^ -(value & 1);
+int _decodeZigZag(int value) => ((value >> 1) ^ -(value & 1)).toSigned(32);
 
 Iterable<TilePoint> decodePoints(List<int> geometry) sync* {
   final it = geometry.iterator;

diff --git a/test/src/model/geometry_decoding_test.dart b/test/src/model/geometry_decoding_test.dart
@@ -12,7 +12,7 @@ const closePath = 0x7;
 
 int command(int command, int length) => length << 3 | command;
 
-int zigZag(int n) => (n << 1) ^ (n >> 31);
+int zigZag(int n) => ((n << 1) ^ (n >> 31)).toSigned(32);
 
 void main() {
   final uiGeometry = UiGeometry();