fixes [Feature] Support optional rotation for non line labels like ci…

…ty, area, country etc. greensopinion#76

lib/src/features/feature_renderer.dart

@@ -9,23 +9,20 @@ import 'symbol_line_renderer.dart';
 import 'symbol_point_renderer.dart';
 
 abstract class FeatureRenderer {
-  void render(
-    Context context,
-    ThemeLayerType layerType,
-    Style style,
-    TileLayer layer,
-    TileFeature feature,
-  );
+  void render(Context context, ThemeLayerType layerType, Style style,
+      TileLayer layer, TileFeature feature, double rotation);
 }
 
 class FeatureDispatcher extends FeatureRenderer {
   final Logger logger;
   final Map<ThemeLayerType, FeatureRenderer> typeToRenderer;
   final Map<TileFeatureType, FeatureRenderer> symbolTypeToRenderer;
+  final double rotation;
 
-  FeatureDispatcher(this.logger)
+  FeatureDispatcher(this.logger, {this.rotation = 0})
       : typeToRenderer = createDispatchMapping(logger),
-        symbolTypeToRenderer = createSymbolDispatchMapping(logger);
+        symbolTypeToRenderer =
+            createSymbolDispatchMapping(logger, rotation: rotation);
 
   @override
   void render(
@@ -34,6 +31,7 @@ class FeatureDispatcher extends FeatureRenderer {
     Style style,
     TileLayer layer,
     TileFeature feature,
+    double rotation,
   ) {
     FeatureRenderer? delegate;
     if (layerType == ThemeLayerType.symbol) {
@@ -46,7 +44,7 @@ class FeatureDispatcher extends FeatureRenderer {
       logger.warn(() =>
           'layer type $layerType feature ${feature.type} is not implemented');
     } else {
-      delegate.render(context, layerType, style, layer, feature);
+      delegate.render(context, layerType, style, layer, feature, rotation);
     }
   }
 
@@ -60,7 +58,8 @@ class FeatureDispatcher extends FeatureRenderer {
   }
 
   static Map<TileFeatureType, FeatureRenderer> createSymbolDispatchMapping(
-      Logger logger) {
+      Logger logger,
+      {double rotation = 0}) {
     return {
       TileFeatureType.point: SymbolPointRenderer(logger),
       TileFeatureType.linestring: SymbolLineRenderer(logger),

lib/src/features/fill_renderer.dart

@@ -15,6 +15,7 @@ class FillRenderer extends FeatureRenderer {
     Style style,
     TileLayer layer,
     TileFeature feature,
+    double rotation,
   ) {
     if (!feature.hasPaths) {
       return;

lib/src/features/line_renderer.dart

@@ -18,6 +18,7 @@ class LineRenderer extends FeatureRenderer {
     Style style,
     TileLayer layer,
     TileFeature feature,
+    double rotation,
   ) {
     if (!feature.hasPaths) {
       return;

lib/src/features/symbol_line_renderer.dart

@@ -21,6 +21,7 @@ class SymbolLineRenderer extends FeatureRenderer {
     Style style,
     TileLayer layer,
     TileFeature feature,
+    double rotation,
   ) {
     final textPaint = style.textPaint;
     final textLayout = style.textLayout;

lib/src/features/symbol_point_renderer.dart

@@ -1,3 +1,4 @@
+import 'dart:math';
 import 'dart:ui';
 
 import '../../vector_tile_renderer.dart';
@@ -12,6 +13,7 @@ import 'text_wrapper.dart';
 class SymbolPointRenderer extends FeatureRenderer {
   final Logger logger;
   SymbolPointRenderer(this.logger);
+  double degrees2Radians = pi / 180.0;
 
   @override
   void render(
@@ -20,6 +22,7 @@ class SymbolPointRenderer extends FeatureRenderer {
     Style style,
     TileLayer layer,
     TileFeature feature,
+    double rotation,
   ) {
     final textPaint = style.textPaint;
     final textLayout = style.textLayout;
@@ -58,8 +61,13 @@ class SymbolPointRenderer extends FeatureRenderer {
       }
 
       context.tileSpaceMapper.drawInPixelSpace(() {
+        context.canvas.translate(offset.dx, offset.dy);
+        context.canvas.rotate(-degrees2Radians * rotation);
+        context.canvas.translate(-offset.dx, -offset.dy);
         textApproximation.renderer.render(offset);
       });
+
+      context.canvas.restore();
     }
   }
 

lib/src/renderer.dart

@@ -15,12 +15,15 @@ class Renderer {
   final Logger logger;
   final FeatureDispatcher featureRenderer;
   final TextPainterProvider painterProvider;
-  Renderer(
-      {required this.theme,
-      this.painterProvider = const DefaultTextPainterProvider(),
-      Logger? logger})
-      : logger = logger ?? const Logger.noop(),
-        featureRenderer = FeatureDispatcher(logger ?? const Logger.noop());
+  final double rotation;
+  Renderer({
+    required this.theme,
+    this.painterProvider = const DefaultTextPainterProvider(),
+    Logger? logger,
+    this.rotation = 0,
+  })  : logger = logger ?? const Logger.noop(),
+        featureRenderer = FeatureDispatcher(logger ?? const Logger.noop(),
+            rotation: rotation);
 
   /// renders the given tile to the canvas
   ///
@@ -58,7 +61,7 @@ class Renderer {
       final effectiveTheme = theme.atZoom(zoom);
       for (final themeLayer in effectiveTheme.layers) {
         logger.log(() => 'rendering theme layer ${themeLayer.id}');
-        themeLayer.render(context);
+        themeLayer.render(context, rotation: rotation);
       }
       canvas.restore();
     });

lib/src/themes/theme.dart

@@ -58,5 +58,5 @@ abstract class ThemeLayer {
 
   String? get tileSource;
 
-  void render(Context context);
+  void render(Context context, {double rotation = 0});
 }

lib/src/themes/theme_layers.dart

@@ -23,7 +23,7 @@ class DefaultLayer extends ThemeLayer {
       : super(id, type, minzoom: minzoom, maxzoom: maxzoom, metadata: metadata);
 
   @override
-  void render(Context context) {
+  void render(Context context, {double rotation = 0}) {
     final layers = selector.select(context.tileset, context.zoom.truncate());
     if (layers.isEmpty) {
       return;
@@ -52,6 +52,7 @@ class DefaultLayer extends ThemeLayer {
             style,
             feature.layer,
             feature.feature,
+            rotation,
           );
         }
       });
@@ -70,7 +71,7 @@ class BackgroundLayer extends ThemeLayer {
             minzoom: 0, maxzoom: 24, metadata: metadata);
 
   @override
-  void render(Context context) {
+  void render(Context context, {double rotation = 0}) {
     context.logger.log(() => 'rendering $id');
     final color = fillColor.evaluate(EvaluationContext(
         () => {}, TileFeatureType.background, context.logger,