start packaging

packages/repl-react/useCycle.ts

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+import { useEffect, useState } from 'react';
+import type { ToneEventCallback } from 'tone';
+import * as Tone from 'tone';
+import { Hap, State, TimeSpan } from '../core/strudel.mjs';
+
+export declare interface UseCycleProps {
+  onEvent: ToneEventCallback<any>;
+  onQuery?: (state: State) => Hap[];
+  onSchedule?: (events: Hap[], cycle: number) => void;
+  onDraw?: ToneEventCallback<any>;
+  ready?: boolean; // if false, query will not be called on change props
+}
+
+function useCycle(props: UseCycleProps) {
+  // onX must use useCallback!
+  const { onEvent, onQuery, onSchedule, ready = true, onDraw } = props;
+  const [started, setStarted] = useState(false);
+  const cycleDuration = 1;
+  const activeCycle = () => Math.floor(Tone.getTransport().seconds / cycleDuration);
+
+  // pull events with onQuery + count up to next cycle
+  const query = (cycle = activeCycle()) => {
+    const timespan = new TimeSpan(cycle, cycle + 1);
+    const events = onQuery?.(new State(timespan)) || [];
+    onSchedule?.(events, cycle);
+    // cancel events after current query. makes sure no old events are player for rescheduled cycles
+    // console.log('schedule', cycle);
+    // query next cycle in the middle of the current
+    const cancelFrom = timespan.begin.valueOf();
+    Tone.getTransport().cancel(cancelFrom);
+    // const queryNextTime = (cycle + 1) * cycleDuration - 0.1;
+    const queryNextTime = (cycle + 1) * cycleDuration - 0.5;
+
+    // if queryNextTime would be before current time, execute directly (+0.1 for safety that it won't miss)
+    const t = Math.max(Tone.getTransport().seconds, queryNextTime) + 0.1;
+    Tone.getTransport().schedule(() => {
+      query(cycle + 1);
+    }, t);
+
+    // schedule events for next cycle
+    events
+      ?.filter((event) => event.part.begin.equals(event.whole.begin))
+      .forEach((event) => {
+        Tone.getTransport().schedule((time) => {
+          const toneEvent = {
+            time: event.whole.begin.valueOf(),
+            duration: event.whole.end.sub(event.whole.begin).valueOf(),
+            value: event.value,
+            context: event.context,
+          };
+          onEvent(time, toneEvent);
+          Tone.Draw.schedule(() => {
+            // do drawing or DOM manipulation here
+            onDraw?.(time, toneEvent);
+          }, time);
+        }, event.part.begin.valueOf());
+      });
+  };
+
+  useEffect(() => {
+    ready && query();
+  }, [onEvent, onSchedule, onQuery, onDraw, ready]);
+
+  const start = async () => {
+    setStarted(true);
+    await Tone.start();
+    Tone.getTransport().start('+0.1');
+  };
+  const stop = () => {
+    Tone.getTransport().pause();
+    setStarted(false);
+  };
+  const toggle = () => (started ? stop() : start());
+  return {
+    start,
+    stop,
+    onEvent,
+    started,
+    setStarted,
+    toggle,
+    query,
+    activeCycle,
+  };
+}
+
+export default useCycle;