Basic modern raster tile layer working

Author: JaffaKetchup

example/lib/pages/home.dart

@@ -38,7 +38,10 @@ class _HomePageState extends State<HomePage> {
               initialZoom: 5,
             ),
             children: [
-              openStreetMapTileLayer,
+              RasterTileLayer.simple(
+                urlTemplate: 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
+                uaIdentifier: 'dev.fleaflet.flutter_map.demo',
+              ),
               RichAttributionWidget(
                 popupInitialDisplayDuration: const Duration(seconds: 5),
                 animationConfig: const ScaleRAWA(),

lib/flutter_map.dart

@@ -29,6 +29,10 @@ export 'package:flutter_map/src/layer/attribution_layer/rich/widget.dart';
 export 'package:flutter_map/src/layer/attribution_layer/simple.dart';
 export 'package:flutter_map/src/layer/circle_layer/circle_layer.dart';
 export 'package:flutter_map/src/layer/marker_layer/marker_layer.dart';
+export 'package:flutter_map/src/layer/modern_tile_layer/source_generators/source_generator.dart';
+export 'package:flutter_map/src/layer/modern_tile_layer/source_generators/wms.dart';
+export 'package:flutter_map/src/layer/modern_tile_layer/source_generators/xyz.dart';
+export 'package:flutter_map/src/layer/modern_tile_layer/tile_layers/raster/tile_layer.dart';
 export 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/built_in/built_in_caching_provider.dart';
 export 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/caching_provider.dart';
 export 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/disabled/disabled_caching_provider.dart';

lib/src/layer/modern_tile_layer/base_tile_data.dart

@@ -1,33 +1,33 @@
 import 'dart:async';
 
 import 'package:flutter_map/src/layer/modern_tile_layer/base_tile_layer.dart';
+import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/tile_loader.dart';
 import 'package:meta/meta.dart';
 
-/// Data associated with a particular tile coordinate which 'loads'
-/// asynchronously.
-///
-/// These are generated by the [BaseTileLayer.tileLoader] and consumed by the
+/// Data associated with a particular tile coordinate, which allows
+/// bi-directional communication between the [TileLoader] and
 /// [BaseTileLayer.renderer].
 ///
-/// Association with a tile coordinate is made in the tile layer.
-///
-/// It is up to the implementation as to what 'loads' means. However, the
-/// [BaseTileLayer] will use [whenLoaded], [isLoaded], and [dispose] to manage
-/// (such as pruning) the tile for the renderer.
+/// The tile layer's internal logic consumes this interface's fields, and can
+/// also manipulate the renderer.
 abstract interface class BaseTileData {
-  /// Completes when the underlying resource is 'loaded'
-  Future<void> get whenLoaded;
-
-  /// Whether the underlying resource is 'loaded'
-  bool get isLoaded;
+  /// Should be completed when the tile is fully optically visible: the tile
+  /// layer will start a prune of eligible tiles, and this tile will become
+  /// eligible for pruning.
+  ///
+  /// If the tile never becomes fully optically visible, this shouldn't usually
+  /// be completed.
+  Future<void> get triggerPrune;
 
-  /// Called when a tile is removed from the map of visible tiles
+  /// Called when a tile is removed from the map of visible tiles passed to the
+  /// renderer.
   ///
   /// This should usually be used to abort loading of the underlying resource
   /// if it has not yet loaded, or release the resources held by it if already
   /// loaded.
   ///
-  /// This should not usually be called externally.
+  /// If called, then it is assumed that the tile layer's internal logic no
+  /// longer cares about any other field in the object.
   @internal
   void dispose();
 }
@@ -54,7 +54,7 @@ class WrapperTileData<D extends Object?> implements BaseTileData {
   ///
   /// This never completes if the data completes to an error.
   @override
-  Future<D> get whenLoaded => _loadedTracker.future;
+  Future<D> get triggerPrune => _loadedTracker.future;
 
   /// Whether [data] represents the loaded data
   @override

lib/src/layer/modern_tile_layer/base_tile_layer.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:collection';
 
 import 'package:flutter/widgets.dart';
@@ -66,8 +67,9 @@ class _BaseTileLayerState<D extends BaseTileData>
       final key = (coordinates: coordinates, layerKey: layerKey);
       tiles.putIfAbsent(
         key,
-        () => widget.tileLoader(coordinates, widget.options)
-          ..whenLoaded.then((_) => _pruneOnLoadedTile(key)),
+        () => _TileDataWithPrunableIndicator(
+          widget.tileLoader(coordinates, widget.options),
+        )..triggerPrune.then((_) => _pruneOnLoadedTile(key)),
         // TODO: Consider how to handle errors
       );
     }
@@ -90,7 +92,7 @@ class _BaseTileLayerState<D extends BaseTileData>
               visibleTileCoordinates.contains(tile.key.coordinates) &&
               tile.key.layerKey == layerKey,
         )
-        .every((tile) => tile.value.isLoaded);
+        .every((tile) => tile.value.isPrunable);
     if (allLoaded) {
       tiles.removeWhere(
         (key, _) => !visibleTileCoordinates.contains(key.coordinates),
@@ -101,7 +103,7 @@ class _BaseTileLayerState<D extends BaseTileData>
       context,
       layerKey,
       widget.options,
-      Map.unmodifiable(tiles),
+      Map.unmodifiable(tiles.map((k, v) => MapEntry(k, v._data))),
     );
   }
 
@@ -112,7 +114,7 @@ class _BaseTileLayerState<D extends BaseTileData>
     // Remove all identical tiles of other (old) keys. aka replace my ancestor
     tiles.removeWhere(
       (otherKey, otherData) =>
-          otherData.isLoaded &&
+          otherData.isPrunable &&
           otherKey.coordinates == key.coordinates &&
           otherKey.layerKey != key.layerKey,
     );
@@ -123,7 +125,7 @@ class _BaseTileLayerState<D extends BaseTileData>
       // or not
       tiles.removeWhere(
         (otherKey, otherData) =>
-            otherData.isLoaded && otherKey.coordinates == childCoordinates,
+            otherData.isPrunable && otherKey.coordinates == childCoordinates,
       );
     }
 
@@ -144,7 +146,7 @@ class _BaseTileLayerState<D extends BaseTileData>
                 siblingCoordinates.contains(other.key.coordinates) &&
                 other.key.layerKey == key.layerKey,
           )
-          .every((other) => other.value.isLoaded);
+          .every((other) => other.value.isPrunable);
 
       if (allLoaded) {
         // Prune parent if me and my siblings are all loaded
@@ -235,17 +237,34 @@ extension _ParentChildTraversal on TileCoordinates {
 typedef _TileKey = ({TileCoordinates coordinates, Object layerKey});
 
 extension type _TilesTracker<D extends BaseTileData>._(
-    SplayTreeMap<_TileKey, D> map) implements SplayTreeMap<_TileKey, D> {
+        Map<_TileKey, _TileDataWithPrunableIndicator<D>> _map)
+    implements Map<_TileKey, _TileDataWithPrunableIndicator<D>> {
   _TilesTracker()
       : this._(
-          SplayTreeMap<_TileKey, D>(
-            (a, b) =>
+          Map<_TileKey, _TileDataWithPrunableIndicator<D>>(
+              /*(a, b) =>
                 a.coordinates.z.compareTo(b.coordinates.z) |
                 a.coordinates.x.compareTo(b.coordinates.x) |
-                a.coordinates.y.compareTo(b.coordinates.y),
-          ),
+                a.coordinates.y.compareTo(b.coordinates.y),*/
+              ),
         );
 
   @redeclare
-  D? remove(Object? key) => map.remove(key)?..dispose();
+  D? remove(Object? key) => (_map.remove(key)?..dispose())?._data;
+}
+
+class _TileDataWithPrunableIndicator<D extends BaseTileData> {
+  _TileDataWithPrunableIndicator(D data) : _data = data {
+    _data.triggerPrune.then((_) => isPrunable = true);
+  }
+
+  final D _data;
+  Future<void> get triggerPrune => _data.triggerPrune;
+  void dispose() => _data.dispose();
+
+  /// `true` when [BaseTileData.triggerPrune] has completed.
+  ///
+  /// Triggering pruning implies being fully loaded and therefore ready for self
+  /// pruning.
+  bool isPrunable = false;
 }

lib/src/layer/modern_tile_layer/tile_layers/raster/tile_layer.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/widgets.dart';
+import 'package:flutter_map/flutter_map.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/base_tile_layer.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/options.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/source_generators/source_generator.dart';
@@ -9,6 +10,7 @@ import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/raster/tile_
 import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/raster/tile_loader.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/tile_source.dart';
 import 'package:flutter_map/src/layer/tile_layer/tile_coordinates.dart';
+import 'package:flutter_map/src/layer/tile_layer/tile_scale_calculator.dart';
 
 class RasterTileLayer extends StatefulWidget {
   const RasterTileLayer({
@@ -39,7 +41,7 @@ class _RasterTileLayerState extends State<RasterTileLayer> {
   Widget build(BuildContext context) => BaseTileLayer(
         options: widget.options,
         tileLoader: RasterTileLoader(
-          sourceGenerator: const XYZSourceGenerator(uriTemplates: ['']),
+          sourceGenerator: widget.sourceGenerator,
           bytesFetcher: widget.bytesFetcher,
         ),
         renderer: (context, layerKey, options, visibleTiles) => _RasterRenderer(
@@ -69,19 +71,36 @@ class __RasterRendererState extends State<_RasterRenderer> {
   //final Map<({TileCoordinates coordinates, Object layerKey}),
   //    TileData<Uint8List>> visibleTiles = {};
 
+  final _tileScaleCalculator =
+      TileScaleCalculator(crs: Epsg3857(), tileDimension: 256);
+
   @override
   void didUpdateWidget(covariant _RasterRenderer oldWidget) {
     super.didUpdateWidget(oldWidget);
   }
 
   @override
   Widget build(BuildContext context) {
+    final map = MapCamera.of(context);
+
+    _tileScaleCalculator.clearCacheUnlessZoomMatches(map.zoom);
+
     return CustomPaint(
       size: Size.infinite,
       willChange: true,
       painter: _RasterPainter(
         options: widget.options,
-        visibleTiles: widget.visibleTiles,
+        visibleTiles: widget.visibleTiles.entries.map(
+          (tile) => (
+            coordinates: tile.key.coordinates,
+            scaledTileDimension: _tileScaleCalculator.scaledTileDimension(
+              map.zoom,
+              tile.key.coordinates.z,
+            ),
+            currentPixelOrigin: map.pixelOrigin,
+            data: tile.value,
+          ),
+        ),
         //tiles: tiles..sort(renderOrder),
         //tilePaint: widget.tilePaint,
         //tileOverlayPainter: widget.tileOverlayPainter,
@@ -92,24 +111,53 @@ class __RasterRendererState extends State<_RasterRenderer> {
 
 class _RasterPainter extends CustomPainter {
   final TileLayerOptions options;
-  final Map<({TileCoordinates coordinates, Object layerKey}), RasterTileData>
-      visibleTiles;
+  final Iterable<
+      ({
+        TileCoordinates coordinates,
+        double scaledTileDimension,
+        Offset currentPixelOrigin,
+        RasterTileData data
+      })> visibleTiles;
 
   _RasterPainter({
     super.repaint,
     required this.options,
     required this.visibleTiles,
   });
 
+  final Paint _basePaint = (null ?? Paint())
+    ..filterQuality = FilterQuality.high
+    ..isAntiAlias = true;
+
   @override
   void paint(Canvas canvas, Size size) {
-    for (final MapEntry(key: (:coordinates, layerKey: _), value: tile)
-        in visibleTiles.entries) {}
+    for (final tile in visibleTiles) {
+      if (tile.data.loaded?.successfulImageInfo?.image case final image?) {
+        final origin = Offset(
+          tile.coordinates.x * tile.scaledTileDimension -
+              tile.currentPixelOrigin.dx,
+          tile.coordinates.y * tile.scaledTileDimension -
+              tile.currentPixelOrigin.dy,
+        );
+        final destSize = Size.square(tile.scaledTileDimension);
+
+        //final paint = _basePaint
+        //  ..color = (null?.color.withOpacity(tile.tileImage.opacity) ??
+        //      Color.fromRGBO(0, 0, 0, tile.tileImage.opacity));
+
+        canvas.drawImageRect(
+          image,
+          Offset.zero &
+              Size(image.width.toDouble(), image.height.toDouble()), // src
+          origin & destSize, // dest
+          _basePaint,
+        );
+      }
+    }
   }
 
   @override
-  bool shouldRepaint(covariant CustomPainter oldDelegate) {
-    // TODO: implement shouldRepaint
-    throw UnimplementedError();
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return true;
   }
 }

lib/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/built_in/built_in_caching_provider.dart

@@ -1,7 +1,7 @@
 import 'package:flutter_map/flutter_map.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/built_in/impl/stub.dart'
-    if (dart.library.io) 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/source_fetchers/bytes_fetchers/network/caching/built_in/impl/native/native.dart'
-    if (dart.library.js_interop) 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/source_fetchers/bytes_fetchers/network/caching/built_in/impl/web/web.dart';
+    if (dart.library.io) 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/built_in/impl/native/native.dart'
+    if (dart.library.js_interop) 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/caching/built_in/impl/web/web.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/tile_loader/bytes_fetchers/network/fetcher/network.dart';
 import 'package:uuid/data.dart';
 import 'package:uuid/rng.dart';

lib/src/layer/modern_tile_layer/tile_loader/raster/tile_data.dart

@@ -31,10 +31,8 @@ class RasterTileData implements BaseTileData {
 
   final _loadedTracker = Completer<void>();
   @override
-  Future<void> get whenLoaded => _loadedTracker.future;
+  Future<void> get triggerPrune => _loadedTracker.future;
 
-  @override
-  bool get isLoaded => loaded != null;
   ({
     DateTime time,
     ImageInfo? successfulImageInfo,

lib/src/layer/modern_tile_layer/tile_loader/tile_loader.dart

@@ -1,13 +1,23 @@
 import 'package:flutter_map/src/layer/modern_tile_layer/base_tile_data.dart';
+import 'package:flutter_map/src/layer/modern_tile_layer/base_tile_layer.dart';
 import 'package:flutter_map/src/layer/modern_tile_layer/options.dart';
 import 'package:flutter_map/src/layer/tile_layer/tile_coordinates.dart';
 import 'package:meta/meta.dart';
 
 /// Responsible for generating a tile's data ([D]), given the [TileCoordinates]
 /// and ambient [TileLayerOptions].
+///
+/// Once a tile has been generated, it is passed to the [BaseTileLayer.renderer]
+/// for rendering.
 @immutable
 abstract interface class TileLoader<D extends BaseTileData> {
   /// Generate data ([D]) for the tile at [coordinates], with the ambient layer
   /// [options].
+  ///
+  /// The data must be generated synchronously. However, the interface of
+  /// [BaseTileData] allows for integration of asynchronous work with the tile
+  /// layer.
+  ///
+  /// If this throws an error then the tile will not be rendered.
   D call(TileCoordinates coordinates, TileLayerOptions options);
 }