perf!: optimize CRS performance and add micro-benchmark of limited ex…

…pressiveness (#1727)

benchmark/crs.dart

@@ -0,0 +1,107 @@
+import 'dart:async';
+import 'dart:math' as math;
+
+import 'package:flutter_map/src/geo/crs.dart';
+import 'package:latlong2/latlong.dart';
+import 'package:logger/logger.dart';
+
+class NoFilter extends LogFilter {
+  @override
+  bool shouldLog(LogEvent event) => true;
+}
+
+typedef Result = ({
+  String name,
+  Duration duration,
+});
+
+Future<Result> timedRun(String name, dynamic Function() body) async {
+  Logger().i('running $name...');
+  final watch = Stopwatch()..start();
+  await body();
+  watch.stop();
+
+  return (name: name, duration: watch.elapsed);
+}
+
+// NOTE: to have a more prod like comparison, run with:
+//     $ dart compile exe benchmark/crs.dart && ./benchmark/crs.exe
+//
+// If you run in JIT mode, the resulting execution times will be a lot more similar.
+Future<void> main() async {
+  Logger.level = Level.all;
+  Logger.defaultFilter = () => NoFilter();
+  Logger.defaultPrinter = () => SimplePrinter();
+
+  final results = <Result>[];
+  const N = 100000000;
+
+  const crs = Epsg3857();
+  results.add(await timedRun('Concrete type: ${crs.code}.latLngToXY()', () {
+    double x = 0;
+    double y = 0;
+    for (int i = 0; i < N; ++i) {
+      final latlng = LatLng((i % 90).toDouble(), (i % 180).toDouble());
+      final (cx, cy) = crs.latLngToXY(latlng, 1);
+      x += cx;
+      y += cy;
+    }
+    return x + y;
+  }));
+
+  results.add(await timedRun('Concrete type: ${crs.code}.latLngToPoint()', () {
+    double x = 0;
+    double y = 0;
+    for (int i = 0; i < N; ++i) {
+      final latlng = LatLng((i % 90).toDouble(), (i % 180).toDouble());
+      final p = crs.latLngToPoint(latlng, 1);
+      x += p.x;
+      y += p.y;
+    }
+    return x + y;
+  }));
+
+  const crss = <Crs>[
+    Epsg3857(),
+    Epsg4326(),
+  ];
+
+  for (final crs in crss) {
+    results.add(await timedRun('${crs.code}.latLngToXY()', () {
+      double x = 0;
+      double y = 0;
+      for (int i = 0; i < N; ++i) {
+        final latlng = LatLng((i % 90).toDouble(), (i % 180).toDouble());
+        final (cx, cy) = crs.latLngToXY(latlng, 1);
+        x += cx;
+        y += cy;
+      }
+      return x + y;
+    }));
+
+    results.add(await timedRun('${crs.code}.latlngToPoint()', () {
+      double x = 0;
+      double y = 0;
+      for (int i = 0; i < N; ++i) {
+        final latlng = LatLng((i % 90).toDouble(), (i % 180).toDouble());
+        final point = crs.latLngToPoint(latlng, 1);
+        x += point.x;
+        y += point.y;
+      }
+      return x + y;
+    }));
+
+    results.add(await timedRun('${crs.code}.pointToLatLng()', () {
+      double x = 0;
+      double y = 0;
+      for (int i = 0; i < N; ++i) {
+        final latlng = crs.pointToLatLng(math.Point<double>(x, y), 1);
+        x += latlng.longitude;
+        y += latlng.latitude;
+      }
+      return x + y;
+    }));
+  }
+
+  Logger().i('Results:\n${results.map((r) => r.toString()).join('\n')}');
+}

example/lib/pages/custom_crs/custom_crs.dart

@@ -83,8 +83,6 @@ class CustomCrsPageState extends State<CustomCrsPage> {
       // Scale factors (pixels per projection unit, for example pixels/meter) for zoom levels;
       // specify either scales or resolutions, not both
       scales: null,
-      // The transformation to use when transforming projected coordinates into pixel coordinates
-      transformation: null,
     );
   }
 

example/lib/pages/epsg3413_crs.dart

@@ -64,7 +64,6 @@ class EPSG3413PageState extends State<EPSG3413Page> {
       bounds: epsg3413Bounds,
       origins: const [Point(0, 0)],
       scales: null,
-      transformation: null,
     );
   }