Enabling heatmaps (#171)

* heatmaps

* updated flutter version

* flutter downgrade

packages/atlas/CHANGELOG.md

@@ -1,5 +1,9 @@
 # atlas
 
+## v1.0.22 (2024-03-21)
+
+- Added support for `Heatmaps`
+
 ## v1.0.21 (2024-02-23)
 
 - Added `onMapLoaded` parameter on `Provider`

packages/atlas/lib/atlas.dart

@@ -12,6 +12,10 @@ export 'src/cluster.dart';
 export 'src/cluster_icon.dart';
 export 'src/congestion_level_route.dart';
 export 'src/device_location.dart';
+export 'src/heatmap/heatcolor.dart';
+export 'src/heatmap/heatcolor_interpolation.dart';
+export 'src/heatmap/heatmap.dart';
+export 'src/heatmap/heatpoint.dart';
 export 'src/lat_lng.dart';
 export 'src/lat_lng_bounds.dart';
 export 'src/map_language.dart';

packages/atlas/lib/src/atlas.dart

@@ -142,6 +142,9 @@ class Atlas extends StatelessWidget {
   /// Callback executed when the map is loaded and is on the screen
   final VoidCallback? onMapLoaded;
 
+  /// Callback executed when the map is loaded and is on the screen
+  final Heatmap? heatmap;
+
   Atlas({
     Key? key,
     required this.initialCameraPosition,
@@ -175,6 +178,7 @@ class Atlas extends StatelessWidget {
     this.maxZoom,
     this.onPolylineTap,
     this.onMapLoaded,
+    this.heatmap,
   })  : markers = markers ?? Set<Marker>(),
         callouts = callouts ?? Set<Callout>(),
         circles = circles ?? Set<Circle>(),
@@ -224,6 +228,7 @@ class Atlas extends StatelessWidget {
       maxZoom: maxZoom,
       onPolylineTap: onPolylineTap,
       onMapLoaded: onMapLoaded,
+      heatmap: heatmap,
     );
   }
 }

packages/atlas/lib/src/heatmap/heatcolor.dart

@@ -0,0 +1,24 @@
+import 'dart:ui';
+
+import 'heatcolor_interpolation.dart';
+
+/// Defines the color of each pixel based on its density value in a heatmap
+
+class Heatcolor {
+  final HeatcolorInterpolation interpolation;
+  final Map<double, Color> densityColors;
+
+  Heatcolor({required this.interpolation, required this.densityColors});
+
+  String toProperty() {
+    final density = densityColors.keys.map((density) {
+      final color = densityColors[density]!.toProperty();
+      return '$density,"$color"';
+    }).join(',');
+    return '["interpolate",${interpolation.toProperty()},["heatmap-density"],$density]';
+  }
+}
+
+extension ColorProperty on Color {
+  String toProperty() => 'rgba($red,$green,$blue,$alpha)';
+}

packages/atlas/lib/src/heatmap/heatcolor_interpolation.dart

@@ -0,0 +1,27 @@
+/// Produces continuous, smooth results by interpolating between pairs of input and output value
+
+abstract class HeatcolorInterpolation {
+  String toProperty();
+}
+
+class LinearInterpolation extends HeatcolorInterpolation {
+  @override
+  String toProperty() => '["linear"]';
+}
+
+class ExponentialInterpolation extends HeatcolorInterpolation {
+  final double base;
+  ExponentialInterpolation(this.base);
+  @override
+  String toProperty() => '["exponential", $base]';
+}
+
+class CubitInterpolation extends HeatcolorInterpolation {
+  final double x1;
+  final double y1;
+  final double x2;
+  final double y2;
+  CubitInterpolation(this.x1, this.y1, this.x2, this.y2);
+  @override
+  String toProperty() => '["cubic-bezier"], $x1, $y1, $x2, $y2]';
+}

packages/atlas/lib/src/heatmap/heatmap.dart

@@ -0,0 +1,13 @@
+import 'package:atlas/src/heatmap/heatcolor.dart';
+
+import 'heatpoint.dart';
+
+/// Visualization to depict the intensity of data at geographical points.
+
+class Heatmap {
+  final Set<Heatpoint> heatpoints;
+  final Heatcolor? heatcolor;
+  final bool showCounter;
+
+  const Heatmap({required this.heatpoints, this.heatcolor, this.showCounter = false});
+}

packages/atlas/lib/src/heatmap/heatpoint.dart

@@ -0,0 +1,11 @@
+import 'package:atlas/src/lat_lng.dart';
+
+/// The points where to build the heatmaps
+
+class Heatpoint {
+  final String id;
+  final LatLng position;
+  final int counter;
+
+  const Heatpoint({required this.id, required this.position, required this.counter});
+}

packages/atlas/lib/src/provider.dart

@@ -48,5 +48,6 @@ abstract class Provider {
     final double? minZoom,
     final double? maxZoom,
     final VoidCallback? onMapLoaded,
+    final Heatmap? heatmap,
   });
 }

packages/atlas/pubspec.yaml

@@ -1,6 +1,6 @@
 name: atlas
 description: An extensible map abstraction for Flutter with support for multiple map providers
-version: 1.0.21
+version: 1.0.22
 repository: https://github.com/bmw-tech/atlas
 issue_tracker: https://github.com/bmw-tech/atlas/issues
 homepage: https://bmw-tech.github.io/atlas

packages/atlas/test/heatmap/heatcolor_interpolation_test.dart

@@ -0,0 +1,26 @@
+import 'package:atlas/src/heatmap/heatcolor_interpolation.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('HeatcolorInterpolation Tests', () {
+    test('LinearInterpolation returns correct property', () {
+      final interpolation = LinearInterpolation();
+      expect(interpolation.toProperty(), '["linear"]');
+    });
+
+    test('ExponentialInterpolation returns correct property', () {
+      final base = 2.0;
+      final interpolation = ExponentialInterpolation(base);
+      expect(interpolation.toProperty(), '["exponential", $base]');
+    });
+
+    test('CubitInterpolation returns correct property', () {
+      final x1 = 0.42;
+      final y1 = 0.0;
+      final x2 = 0.58;
+      final y2 = 1.0;
+      final interpolation = CubitInterpolation(x1, y1, x2, y2);
+      expect(interpolation.toProperty(), '["cubic-bezier"], $x1, $y1, $x2, $y2]');
+    });
+  });
+}

packages/atlas/test/heatmap/heatcolor_test.dart

@@ -0,0 +1,25 @@
+import 'dart:ui';
+
+import 'package:atlas/src/heatmap/heatcolor.dart';
+import 'package:atlas/src/heatmap/heatcolor_interpolation.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('Heatcolor Tests', () {
+    test('Heatcolor returns correct property string', () {
+      final interpolation = LinearInterpolation();
+      final densityColors = {
+        0.0: Color.fromARGB(255, 255, 0, 0), // Red
+        0.5: Color.fromARGB(255, 0, 255, 0), // Green
+        1.0: Color.fromARGB(255, 0, 0, 255), // Blue
+      };
+      final heatcolor = Heatcolor(interpolation: interpolation, densityColors: densityColors);
+      final expectedString = '["interpolate",["linear"],["heatmap-density"],'
+          '0.0,"rgba(255,0,0,255)",'
+          '0.5,"rgba(0,255,0,255)",'
+          '1.0,"rgba(0,0,255,255)"]';
+
+      expect(heatcolor.toProperty(), expectedString);
+    });
+  });
+}

packages/atlas/test/heatmap/heatmap_test.dart

@@ -0,0 +1,35 @@
+import 'package:atlas/atlas.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('Heatmap Tests', () {
+    test('Heatmap is correctly instantiated with default values', () {
+      final heatpoints = <Heatpoint>{
+        Heatpoint(id: '1', position: LatLng(latitude: 37.7749, longitude: -122.4194), counter: 10),
+        Heatpoint(id: '2', position: LatLng(latitude: 34.0522, longitude: -118.2437), counter: 20),
+      };
+      final heatmap = Heatmap(heatpoints: heatpoints);
+
+      expect(heatmap.heatpoints, equals(heatpoints));
+      expect(heatmap.heatcolor, isNull);
+      expect(heatmap.showCounter, isFalse);
+    });
+
+    test('Heatmap correctly assigns non-default values', () {
+      final heatpoints = <Heatpoint>{
+        Heatpoint(id: '1', position: LatLng(latitude: 37.7749, longitude: -122.4194), counter: 10),
+        Heatpoint(id: '2', position: LatLng(latitude: 34.0522, longitude: -118.2437), counter: 20),
+      };
+      final heatcolor = Heatcolor(
+        interpolation: LinearInterpolation(),
+        densityColors: {0.0: Colors.red, 0.5: Colors.green, 1.0: Colors.blue},
+      );
+      final heatmap = Heatmap(heatpoints: heatpoints, heatcolor: heatcolor, showCounter: true);
+
+      expect(heatmap.heatpoints, equals(heatpoints));
+      expect(heatmap.heatcolor, equals(heatcolor));
+      expect(heatmap.showCounter, isTrue);
+    });
+  });
+}

packages/atlas/test/heatmap/heatpoint_test.dart

@@ -0,0 +1,18 @@
+import 'package:atlas/atlas.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('Heatpoint Tests', () {
+    test('Heatpoint properties are correctly assigned', () {
+      final position = LatLng(latitude: 37.7749, longitude: -122.4194);
+      final id = 'testId';
+      final counter = 42;
+
+      final heatpoint = Heatpoint(id: id, position: position, counter: counter);
+
+      expect(heatpoint.id, id);
+      expect(heatpoint.position, position);
+      expect(heatpoint.counter, counter);
+    });
+  });
+}