fix: make horizontal repetition CRS dependent (#1978)

Author: monsieurtanuki

lib/src/geo/crs.dart

@@ -67,6 +67,9 @@ abstract class Crs {
 
   /// Rescales the bounds to a given zoom value.
   Bounds<double>? getProjectedBounds(double zoom);
+
+  /// Returns true if we want the world to be replicated, longitude-wise.
+  bool get replicatesWorldLongitude => false;
 }
 
 /// Internal base class for CRS with a single zoom-level independent transformation.
@@ -175,6 +178,9 @@ class Epsg3857 extends CrsWithStaticTransformation {
     );
     return Point<double>(x, y);
   }
+
+  @override
+  bool get replicatesWorldLongitude => true;
 }
 
 /// EPSG:4326, A common CRS among GIS enthusiasts.

lib/src/gestures/map_interactive_viewer.dart

@@ -883,18 +883,23 @@ class MapInteractiveViewerState extends State<MapInteractiveViewer>
 
     final newCenterPoint = _camera.project(_mapCenterStart) +
         _flingAnimation.value.toPoint().rotate(_camera.rotationRad);
-    final math.Point<double> bestCenterPoint;
-    final double worldSize = _camera.crs.scale(_camera.zoom);
-    if (newCenterPoint.x > worldSize) {
-      bestCenterPoint =
-          math.Point(newCenterPoint.x - worldSize, newCenterPoint.y);
-    } else if (newCenterPoint.x < 0) {
-      bestCenterPoint =
-          math.Point(newCenterPoint.x + worldSize, newCenterPoint.y);
+    final LatLng newCenter;
+    if (!_camera.crs.replicatesWorldLongitude) {
+      newCenter = _camera.unproject(newCenterPoint);
     } else {
-      bestCenterPoint = newCenterPoint;
+      final math.Point<double> bestCenterPoint;
+      final double worldSize = _camera.crs.scale(_camera.zoom);
+      if (newCenterPoint.x > worldSize) {
+        bestCenterPoint =
+            math.Point(newCenterPoint.x - worldSize, newCenterPoint.y);
+      } else if (newCenterPoint.x < 0) {
+        bestCenterPoint =
+            math.Point(newCenterPoint.x + worldSize, newCenterPoint.y);
+      } else {
+        bestCenterPoint = newCenterPoint;
+      }
+      newCenter = _camera.unproject(bestCenterPoint);
     }
-    final newCenter = _camera.unproject(bestCenterPoint);
 
     widget.controller.moveRaw(
       newCenter,

lib/src/layer/tile_layer/tile_coordinates.dart

@@ -20,29 +20,6 @@ class TileCoordinates extends Point<int> {
   /// Create a new [TileCoordinates] instance.
   const TileCoordinates(super.x, super.y, this.z);
 
-  /// Returns a unique value for the same tile on all world replications.
-  factory TileCoordinates.key(TileCoordinates coordinates) {
-    if (coordinates.z < 0) {
-      return coordinates;
-    }
-    final modulo = 1 << coordinates.z;
-    int x = coordinates.x;
-    while (x < 0) {
-      x += modulo;
-    }
-    while (x >= modulo) {
-      x -= modulo;
-    }
-    int y = coordinates.y;
-    while (y < 0) {
-      y += modulo;
-    }
-    while (y >= modulo) {
-      y -= modulo;
-    }
-    return TileCoordinates(x, y, coordinates.z);
-  }
-
   @override
   String toString() => 'TileCoordinate($x, $y, $z)';
 
@@ -70,3 +47,48 @@ class TileCoordinates extends Point<int> {
     return x ^ y << 24 ^ z << 48;
   }
 }
+
+/// Resolves coordinates in the context of world replications.
+///
+/// On maps with world replications, different tile coordinates may actually
+/// refer to the same "resolved" tile coordinate - the coordinate that starts
+/// from 0.
+/// For instance, on zoom level 0, all tile coordinates can be simplified to
+/// (0,0), which is the only tile.
+/// On zoom level 1, (0, 1) and (2, 1) can be simplified to (0, 1), as they both
+/// mean the bottom left tile.
+/// And when we're not in the context of world replications, we don't have to
+/// simplify the tile coordinates: we just return the same value.
+class TileCoordinatesResolver {
+  /// Resolves coordinates in the context of world replications.
+  const TileCoordinatesResolver(this.replicatesWorldLongitude);
+
+  /// True if we simplify the coordinates according to the world replications.
+  final bool replicatesWorldLongitude;
+
+  /// Returns the simplification of the coordinates.
+  TileCoordinates get(TileCoordinates positionCoordinates) {
+    if (!replicatesWorldLongitude) {
+      return positionCoordinates;
+    }
+    if (positionCoordinates.z < 0) {
+      return positionCoordinates;
+    }
+    final modulo = 1 << positionCoordinates.z;
+    int x = positionCoordinates.x;
+    while (x < 0) {
+      x += modulo;
+    }
+    while (x >= modulo) {
+      x -= modulo;
+    }
+    int y = positionCoordinates.y;
+    while (y < 0) {
+      y += modulo;
+    }
+    while (y >= modulo) {
+      y -= modulo;
+    }
+    return TileCoordinates(x, y, positionCoordinates.z);
+  }
+}

lib/src/layer/tile_layer/tile_image_manager.dart

@@ -7,13 +7,11 @@ import 'package:flutter_map/src/layer/tile_layer/tile_bounds/tile_bounds_at_zoom
 import 'package:flutter_map/src/layer/tile_layer/tile_image_view.dart';
 import 'package:flutter_map/src/layer/tile_layer/tile_range.dart';
 import 'package:flutter_map/src/layer/tile_layer/tile_renderer.dart';
-import 'package:meta/meta.dart';
 
-/// Callback definition to crete a [TileImage] for [TileCoordinates].
+/// Callback definition to create a [TileImage] for [TileCoordinates].
 typedef TileCreator = TileImage Function(TileCoordinates coordinates);
 
 /// The [TileImageManager] orchestrates the loading and pruning of tiles.
-@immutable
 class TileImageManager {
   final Set<TileCoordinates> _positionCoordinates = HashSet<TileCoordinates>();
 
@@ -28,31 +26,52 @@ class TileImageManager {
   bool get allLoaded =>
       _tiles.values.none((tile) => tile.loadFinishedAt == null);
 
+  /// Coordinates resolver.
+  TileCoordinatesResolver _resolver = const TileCoordinatesResolver(false);
+
+  /// Sets if we replicate the world longitude in several worlds.
+  void setReplicatesWorldLongitude(bool replicatesWorldLongitude) {
+    if (_resolver.replicatesWorldLongitude == replicatesWorldLongitude) {
+      return;
+    }
+    _resolver = TileCoordinatesResolver(replicatesWorldLongitude);
+  }
+
   /// Filter tiles to only tiles that would be visible on screen. Specifically:
   ///   1. Tiles in the visible range at the target zoom level.
   ///   2. Tiles at non-target zoom level that would cover up holes that would
   ///      be left by tiles in #1, which are not ready yet.
   Iterable<TileRenderer> getTilesToRender({
     required DiscreteTileRange visibleRange,
   }) {
-    final Iterable<TileCoordinates> positionCoordinates = TileImageView(
-      tileImages: _tiles,
-      positionCoordinates: _positionCoordinates,
+    final Iterable<TileCoordinates> positionCoordinates = _getTileImageView(
       visibleRange: visibleRange,
       // `keepRange` is irrelevant here since we're not using the output for
       // pruning storage but rather to decide on what to put on screen.
       keepRange: visibleRange,
     ).renderTiles;
     final List<TileRenderer> tileRenderers = <TileRenderer>[];
     for (final position in positionCoordinates) {
-      final TileImage? tileImage = _tiles[TileCoordinates.key(position)];
+      final TileImage? tileImage = _tiles[_resolver.get(position)];
       if (tileImage != null) {
         tileRenderers.add(TileRenderer(tileImage, position));
       }
     }
     return tileRenderers;
   }
 
+  TileImageView _getTileImageView({
+    required DiscreteTileRange visibleRange,
+    required DiscreteTileRange keepRange,
+  }) =>
+      TileImageView(
+        tileImages: _tiles,
+        positionCoordinates: _positionCoordinates,
+        visibleRange: visibleRange,
+        keepRange: keepRange,
+        resolver: _resolver,
+      );
+
   /// Check if all loaded tiles are within the [minZoom] and [maxZoom] level.
   bool allWithinZoom(double minZoom, double maxZoom) => _tiles.values
       .map((e) => e.coordinates)
@@ -68,7 +87,7 @@ class TileImageManager {
     final notLoaded = <TileImage>[];
 
     for (final coordinates in tileBoundsAtZoom.validCoordinatesIn(tileRange)) {
-      final cleanCoordinates = TileCoordinates.key(coordinates);
+      final cleanCoordinates = _resolver.get(coordinates);
       TileImage? tile = _tiles[cleanCoordinates];
       if (tile == null) {
         tile = createTile(cleanCoordinates);
@@ -97,11 +116,11 @@ class TileImageManager {
     required bool Function(TileImage tileImage) evictImageFromCache,
   }) {
     _positionCoordinates.remove(key);
-    final cleanKey = TileCoordinates.key(key);
+    final cleanKey = _resolver.get(key);
 
     // guard if positionCoordinates with the same tileImage.
     for (final positionCoordinates in _positionCoordinates) {
-      if (TileCoordinates.key(positionCoordinates) == cleanKey) {
+      if (_resolver.get(positionCoordinates) == cleanKey) {
         return;
       }
     }
@@ -167,9 +186,7 @@ class TileImageManager {
     required int pruneBuffer,
     required EvictErrorTileStrategy evictStrategy,
   }) {
-    final pruningState = TileImageView(
-      tileImages: _tiles,
-      positionCoordinates: _positionCoordinates,
+    final pruningState = _getTileImageView(
       visibleRange: visibleRange,
       keepRange: visibleRange.expand(pruneBuffer),
     );
@@ -205,9 +222,7 @@ class TileImageManager {
     required EvictErrorTileStrategy evictStrategy,
   }) {
     _prune(
-      TileImageView(
-        tileImages: _tiles,
-        positionCoordinates: _positionCoordinates,
+      _getTileImageView(
         visibleRange: visibleRange,
         keepRange: visibleRange.expand(pruneBuffer),
       ),

lib/src/layer/tile_layer/tile_image_view.dart

@@ -10,17 +10,21 @@ final class TileImageView {
   final Set<TileCoordinates> _positionCoordinates;
   final DiscreteTileRange _visibleRange;
   final DiscreteTileRange _keepRange;
+  final TileCoordinatesResolver _resolver;
 
   /// Create a new [TileImageView] instance.
   const TileImageView({
     required Map<TileCoordinates, TileImage> tileImages,
     required Set<TileCoordinates> positionCoordinates,
     required DiscreteTileRange visibleRange,
     required DiscreteTileRange keepRange,
+    final TileCoordinatesResolver resolver =
+        const TileCoordinatesResolver(false),
   })  : _tileImages = tileImages,
         _positionCoordinates = positionCoordinates,
         _visibleRange = visibleRange,
-        _keepRange = keepRange;
+        _keepRange = keepRange,
+        _resolver = resolver;
 
   /// Get a list with all tiles that have an error and are outside of the
   /// margin that should get kept.
@@ -37,11 +41,14 @@ final class TileImageView {
   List<TileCoordinates> _errorTilesWithinRange(DiscreteTileRange range) {
     final List<TileCoordinates> result = <TileCoordinates>[];
     for (final positionCoordinates in _positionCoordinates) {
-      if (range.contains(positionCoordinates)) {
+      if (range.contains(
+        positionCoordinates,
+        replicatesWorldLongitude: _resolver.replicatesWorldLongitude,
+      )) {
         continue;
       }
       final TileImage? tileImage =
-          _tileImages[TileCoordinates.key(positionCoordinates)];
+          _tileImages[_resolver.get(positionCoordinates)];
       if (tileImage?.loadError ?? false) {
         result.add(positionCoordinates);
       }
@@ -55,7 +62,10 @@ final class TileImageView {
     final retain = HashSet<TileCoordinates>();
 
     for (final positionCoordinates in _positionCoordinates) {
-      if (!_keepRange.contains(positionCoordinates)) {
+      if (!_keepRange.contains(
+        positionCoordinates,
+        replicatesWorldLongitude: _resolver.replicatesWorldLongitude,
+      )) {
         stale.add(positionCoordinates);
         continue;
       }
@@ -86,14 +96,16 @@ final class TileImageView {
     final retain = HashSet<TileCoordinates>();
 
     for (final positionCoordinates in _positionCoordinates) {
-      if (!_visibleRange.contains(positionCoordinates)) {
+      if (!_visibleRange.contains(
+        positionCoordinates,
+        replicatesWorldLongitude: _resolver.replicatesWorldLongitude,
+      )) {
         continue;
       }
 
       retain.add(positionCoordinates);
 
-      final TileImage? tile =
-          _tileImages[TileCoordinates.key(positionCoordinates)];
+      final TileImage? tile = _tileImages[_resolver.get(positionCoordinates)];
       if (tile == null || !tile.readyToDisplay) {
         final retainedAncestor = _retainAncestor(
           retain,
@@ -131,7 +143,7 @@ final class TileImageView {
     final z2 = z - 1;
     final coords2 = TileCoordinates(x2, y2, z2);
 
-    final tile = _tileImages[TileCoordinates.key(coords2)];
+    final tile = _tileImages[_resolver.get(coords2)];
     if (tile != null) {
       if (tile.readyToDisplay) {
         retain.add(coords2);
@@ -160,7 +172,7 @@ final class TileImageView {
     for (final (i, j) in const [(0, 0), (0, 1), (1, 0), (1, 1)]) {
       final coords = TileCoordinates(2 * x + i, 2 * y + j, z + 1);
 
-      final tile = _tileImages[TileCoordinates.key(coords)];
+      final tile = _tileImages[_resolver.get(coords)];
       if (tile != null) {
         if (tile.readyToDisplay || tile.loadFinishedAt != null) {
           retain.add(coords);

lib/src/layer/tile_layer/tile_layer.dart

@@ -362,6 +362,10 @@ class _TileLayerState extends State<TileLayer> with TickerProviderStateMixin {
     final camera = MapCamera.of(context);
     final mapController = MapController.of(context);
 
+    _tileImageManager.setReplicatesWorldLongitude(
+      camera.crs.replicatesWorldLongitude,
+    );
+
     if (_mapControllerHashCode != mapController.hashCode) {
       _tileUpdateSubscription?.cancel();
 

lib/src/layer/tile_layer/tile_range.dart

@@ -113,7 +113,14 @@ class DiscreteTileRange extends TileRange {
   /// Check if a [Point] is inside of the bounds of the [DiscreteTileRange].
   ///
   /// We use a modulo in order to prevent side-effects at the end of the world.
-  bool contains(Point<int> point) {
+  bool contains(
+    Point<int> point, {
+    bool replicatesWorldLongitude = false,
+  }) {
+    if (!replicatesWorldLongitude) {
+      return _bounds.contains(point);
+    }
+
     final int modulo = 1 << zoom;
 
     bool containsCoordinate(int value, int min, int max) {

lib/src/map/camera/camera.dart

@@ -189,6 +189,9 @@ class MapCamera {
   /// Jumps camera to opposite side of the world to enable seamless scrolling
   /// between 180 and -180 longitude.
   LatLng _adjustPositionForSeamlessScrolling(LatLng? position) {
+    if (!crs.replicatesWorldLongitude) {
+      return position ?? center;
+    }
     if (position == null) {
       return center;
     }