Extensibility, TypeScript and lazy loading

src/components/views/elements/effects/EffectsOverlay.tsx

@@ -0,0 +1,77 @@
+import React, {FunctionComponent, useEffect, useRef} from 'react';
+import dis from '../../../../dispatcher/dispatcher';
+import ICanvasEffect from './ICanvasEffect.js';
+
+type EffectsOverlayProps = {
+    roomWidth: number;
+}
+
+const EffectsOverlay: FunctionComponent<EffectsOverlayProps> = ({roomWidth}) => {
+    const canvasRef = useRef<HTMLCanvasElement>(null);
+    const effectsRef = useRef<Map<String, ICanvasEffect>>(new Map<String, ICanvasEffect>());
+
+    const resize = () => {
+        canvasRef.current.height = window.innerHeight;
+    };
+
+    const lazyLoadEffectModule = async (name: string): Promise<ICanvasEffect> => {
+        if(!name) return null;
+        let effect = effectsRef.current[name] ?? null;
+        if(effect === null) {
+            try {
+                var { default: Effect } = await import(`./${name}`);
+                effect = new Effect();
+                effectsRef.current[name] = effect;
+            } catch (err) {
+                console.warn('Unable to load effect module at \'./${name}\'.', err)
+            }
+        }
+        return effect;
+    }
+
+    const onAction = (payload: { action: string }) => {
+        const actionPrefix = 'effects.';
+        if(payload.action.indexOf(actionPrefix) === 0) {
+            const effect = payload.action.substr(actionPrefix.length);
+            lazyLoadEffectModule(effect).then((module) => module?.start(canvasRef.current));
+        }
+    };
+
+    // on mount
+    useEffect(() => {
+        const dispatcherRef = dis.register(onAction);
+        const canvas = canvasRef.current;
+        canvas.width = roomWidth;
+        canvas.height = window.innerHeight;
+        window.addEventListener('resize', resize, true);
+        
+        return () => {            
+            dis.unregister(dispatcherRef);
+            window.removeEventListener('resize', resize);
+            for(const effect in effectsRef.current) {
+                effectsRef.current[effect]?.stop();
+            }
+        };
+    }, []);
+
+    // on roomWidth change
+    useEffect(() => {
+        canvasRef.current.width = roomWidth;
+    }, [roomWidth]);
+    
+    return (
+        <canvas
+            ref={canvasRef}
+            style={{
+                display: 'block',
+                zIndex: 999999,
+                pointerEvents: 'none',
+                position: 'fixed',
+                top: 0,
+                right: 0,
+            }}
+        />
+    )
+}
+
+export default EffectsOverlay;