Layer proposal

doc/examples/layers/lib/main.dart

@@ -0,0 +1,76 @@
+import 'package:flutter/material.dart' hide Animation;
+import 'package:flame/game.dart';
+import 'package:flame/sprite.dart';
+import 'package:flame/spritesheet.dart';
+import 'package:flame/animation.dart';
+import 'package:flame/layer.dart';
+import 'package:flame/flame.dart';
+
+import 'dart:ui';
+
+void main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+
+  await Flame.util.fullScreen();
+
+  final sprite = await Sprite.loadSprite('sprites.png');
+
+  await Flame.images.load('bomb_ptero.png');
+  final spriteSheet = SpriteSheet(
+      imageName: 'bomb_ptero.png',
+      textureWidth: 48,
+      textureHeight: 32,
+      columns: 4,
+      rows: 1);
+
+  final animation = spriteSheet.createAnimation(0, stepTime: 0.2, to: 3);
+  runApp(LayerGame(sprite, animation).widget);
+}
+
+class LayerGame extends Game {
+  Sprite sprite;
+  Animation animation;
+  Layer layerWithDropShadow;
+  Layer animationLayerWithDropShadow;
+  Layer layerWithoutDropShadow;
+
+  LayerGame(this.sprite, this.animation) {
+    layerWithDropShadow = Layer()..preProcessors.add(ShadowProcessor());
+    animationLayerWithDropShadow = Layer()
+      ..preProcessors.add(ShadowProcessor());
+
+    layerWithoutDropShadow = Layer();
+
+    layerWithoutDropShadow.beginRendering();
+    layerWithDropShadow.beginRendering();
+
+    sprite.renderRect(
+        layerWithoutDropShadow.canvas, const Rect.fromLTWH(50, 50, 200, 200));
+    sprite.renderRect(
+        layerWithDropShadow.canvas, const Rect.fromLTWH(50, 50, 200, 200));
+
+    layerWithoutDropShadow.finishRendering();
+    layerWithDropShadow.finishRendering();
+  }
+
+  @override
+  void update(double dt) {
+    animation.update(dt);
+  }
+
+  @override
+  void render(Canvas canvas) {
+    layerWithoutDropShadow.render(canvas);
+    layerWithDropShadow.render(canvas, y: 250);
+
+    animationLayerWithDropShadow.beginRendering();
+    animation.getSprite().renderRect(animationLayerWithDropShadow.canvas,
+        const Rect.fromLTWH(0, 0, 150, 100));
+    animationLayerWithDropShadow
+      ..finishRendering()
+      ..render(canvas, x: 100, y: 600);
+  }
+
+  @override
+  Color backgroundColor() => const Color(0xFF38607C);
+}