feat: Add a canSee method to the CameraComponent (#2270)

Adding inView method so developers can more easily check if a given component is visible from a camera point of view.

doc/flame/camera_component.md

@@ -177,6 +177,19 @@ The `visibleWorldRect` is a cached property, and it updates automatically whenev
 moves or the viewport changes its size.
 
 
+### Check if a component is visible from the camera point of view
+
+The `CameraComponent` has a method called `canSee` which can be used to check
+if a component is visible from the camera point of view.
+This is useful for example to cull components that are not in view.
+
+```dart
+if (!camera.canSee(component)) {
+ component.removeFromParent(); // Cull the component
+}
+```
+
+
 ## Comparison to the traditional camera
 
 Compared to the normal [Camera](camera_and_viewport.md), the `CameraComponent`

packages/flame/lib/src/camera/camera_component.dart

@@ -278,4 +278,9 @@ class CameraComponent extends Component {
  boundedBehavior.bounds = bounds;
  }
  }
+
+ /// Returns true if this camera is able to see the [component].
+ bool canSee(PositionComponent component) {
+ return visibleWorldRect.overlaps(component.toAbsoluteRect());
+ }
 }

packages/flame/test/camera/camera_component_test.dart

@@ -273,6 +273,40 @@ void main() {
  ),
  );
  });
+
+ testWithFlameGame('component is in view for the camera', (game) async {
+ final world = World();
+ final camera = CameraComponent(
+ world: world,
+ viewport: FixedSizeViewport(60, 40),
+ );
+ game.addAll([world, camera]);
+ await game.ready();
+
+ final component = PositionComponent(
+ size: Vector2(10, 10),
+ position: Vector2(0, 0),
+ );
+
+ expect(camera.canSee(component), isTrue);
+ });
+
+ testWithFlameGame('component is out of view for the camera', (game) async {
+ final world = World();
+ final camera = CameraComponent(
+ world: world,
+ viewport: FixedSizeViewport(60, 40),
+ );
+ game.addAll([world, camera]);
+ await game.ready();
+
+ final component = PositionComponent(
+ size: Vector2(10, 10),
+ position: Vector2(100, 100),
+ );
+
+ expect(camera.canSee(component), isFalse);
+ });
  });
 }