feat(core): allow injectBeforeRender to accept priority as signal

Author: nartc

libs/core/src/lib/utils/before-render.ts

@@ -1,4 +1,4 @@
-import { DestroyRef, Injector, inject } from '@angular/core';
+import { DestroyRef, effect, inject, Injector } from '@angular/core';
 import { assertInjector } from 'ngxtension/assert-injector';
 import { injectStore } from '../store';
 import type { NgtBeforeRenderRecord } from '../types';
@@ -7,35 +7,41 @@ import type { NgtBeforeRenderRecord } from '../types';
  * `injectBeforeRender` invokes its callback on every frame. Hence, the notion of tracking
  * changes (i.e: signals) does not really matter since we're getting latest values of the things we need on every frame anyway.
  *
- * If `priority` is dynamic, consumers should set up `injectBeforeRender` in
- * an `effect` and track `priority` changes. Make use of `onCleanup` to clean up
- * previous before render subscription
+ * If `priority` is a Signal, `injectBeforeRender` will set up an Effect internally and returns the `EffectRef#destroy` instead.
  *
  * @example
  * ```ts
- * const injector = inject(Injector);
- *
- * effect((onCleanup) => {
- *   const priority = this.priority(); // track priority
- *
- *   const sub = injectBeforeRender(
- *    ({ gl, camera }) => {
- *      // before render logic
- *    },
- *    {
- *      priority,
- *      injector, // injector is needed since injectBeforeRender is invoked in effect body
- *    }
- *   });
- *
- *   onCleanup(() => sub());
- * });
+ * const destroy = injectBeforeRender(
+ *  ({ gl, camera }) => {
+ *    // before render logic
+ *  },
+ *  {
+ *    priority: this.priority, // this.priority is a Signal<number>
+ *  }
+ * )
  * ```
  */
 export function injectBeforeRender(
 	cb: NgtBeforeRenderRecord['callback'],
-	{ priority = 0, injector }: { priority?: number; injector?: Injector } = {},
+	{ priority = 0, injector }: { priority?: number | (() => number); injector?: Injector } = {},
 ) {
+	if (typeof priority === 'function') {
+		const effectRef = assertInjector(injectBeforeRender, injector, () => {
+			const store = injectStore();
+			const ref = effect((onCleanup) => {
+				const p = priority();
+				const sub = store.snapshot.internal.subscribe(cb, p, store);
+				onCleanup(() => sub());
+			});
+
+			inject(DestroyRef).onDestroy(() => void ref.destroy());
+
+			return ref;
+		});
+
+		return effectRef.destroy.bind(effectRef);
+	}
+
 	return assertInjector(injectBeforeRender, injector, () => {
 		const store = injectStore();
 		const sub = store.snapshot.internal.subscribe(cb, priority, store);