@tldraw/utils/dist-esm/lib/throttle.mjs

tldraw infinite canvas SDK (private utilities).

const isTest = () => typeof process !== "undefined" && process.env.NODE_ENV === "test" && // @ts-expect-error
!globalThis.__FORCE_RAF_IN_TESTS__;
const fpsQueue = [];
const targetFps = 60;
const targetTimePerFrame = Math.floor(1e3 / targetFps) * 0.9;
let frameRaf;
let flushRaf;
let lastFlushTime = -targetTimePerFrame;
const flush = () => {
  const queue = fpsQueue.splice(0, fpsQueue.length);
  for (const fn of queue) {
    fn();
  }
};
function tick(isOnNextFrame = false) {
  if (frameRaf) return;
  const now = Date.now();
  const elapsed = now - lastFlushTime;
  if (elapsed < targetTimePerFrame) {
    frameRaf = requestAnimationFrame(() => {
      frameRaf = void 0;
      tick(true);
    });
    return;
  }
  if (isOnNextFrame) {
    if (flushRaf) return;
    lastFlushTime = now;
    flush();
  } else {
    if (flushRaf) return;
    flushRaf = requestAnimationFrame(() => {
      flushRaf = void 0;
      lastFlushTime = now;
      flush();
    });
  }
}
function fpsThrottle(fn) {
  if (isTest()) {
    fn.cancel = () => {
      if (frameRaf) {
        cancelAnimationFrame(frameRaf);
        frameRaf = void 0;
      }
      if (flushRaf) {
        cancelAnimationFrame(flushRaf);
        flushRaf = void 0;
      }
    };
    return fn;
  }
  const throttledFn = () => {
    if (fpsQueue.includes(fn)) {
      return;
    }
    fpsQueue.push(fn);
    tick();
  };
  throttledFn.cancel = () => {
    const index = fpsQueue.indexOf(fn);
    if (index > -1) {
      fpsQueue.splice(index, 1);
    }
  };
  return throttledFn;
}
function throttleToNextFrame(fn) {
  if (isTest()) {
    fn();
    return () => void 0;
  }
  if (!fpsQueue.includes(fn)) {
    fpsQueue.push(fn);
    tick();
  }
  return () => {
    const index = fpsQueue.indexOf(fn);
    if (index > -1) {
      fpsQueue.splice(index, 1);
    }
  };
}
export {
  fpsThrottle,
  throttleToNextFrame
};
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