Method scrollToPoint

core/src/components/content/content.tsx:379–426

(x: number | undefined | null, y: number | undefined | null, duration = 0)

   */
  @Method()
  async scrollToPoint(x: number | undefined | null, y: number | undefined | null, duration = 0): Promise<void> {
    const el = await this.getScrollElement();
    if (duration < 32) {
      if (y != null) {
        el.scrollTop = y;
      }
      if (x != null) {
        el.scrollLeft = x;
      }
      return;
    }

    let resolve!: () => void;
    let startTime = 0;
    const promise = new Promise<void>((r) => (resolve = r));
    const fromY = el.scrollTop;
    const fromX = el.scrollLeft;

    const deltaY = y != null ? y - fromY : 0;
    const deltaX = x != null ? x - fromX : 0;

    // scroll loop
    const step = (timeStamp: number) => {
      const linearTime = Math.min(1, (timeStamp - startTime) / duration) - 1;
      const easedT = Math.pow(linearTime, 3) + 1;

      if (deltaY !== 0) {
        el.scrollTop = Math.floor(easedT * deltaY + fromY);
      }
      if (deltaX !== 0) {
        el.scrollLeft = Math.floor(easedT * deltaX + fromX);
      }

      if (easedT < 1) {
        // do not use DomController here
        // must use nativeRaf in order to fire in the next frame
        requestAnimationFrame(step);
      } else {
        resolve();
      }
    };
    // chill out for a frame first
    requestAnimationFrame((ts) => {
      startTime = ts;
      step(ts);
    });
    return promise;
  }

  private onScrollStart() {
    this.isScrolling = true;