_setScrollState() — react Function Reference

Source Code

packages/react-devtools-timeline/src/view-base/VerticalScrollView.js lines 265–296

  _setScrollState(proposedState: ScrollState): boolean {
    const contentHeight = this._contentView.frame.size.height;
    const containerHeight = this.frame.size.height;

    const clampedState = clampState({
      state: proposedState,
      minContentLength: contentHeight,
      maxContentLength: contentHeight,
      containerLength: containerHeight,
    });
    if (!areScrollStatesEqual(clampedState, this._scrollState)) {
      this._scrollState.offset = clampedState.offset;
      this._scrollState.length = clampedState.length;

      this.setNeedsDisplay();

      if (this._onChangeCallback !== null) {
        this._onChangeCallback(clampedState, this.frame.size.height);
      }

      return true;
    }

    // Don't allow wheel events to bubble past this view even if we've scrolled to the edge.
    // It just feels bad to have the scrolling jump unexpectedly from in a container to the outer page.
    // The only exception is when the container fits the content (no scrolling).
    if (contentHeight === containerHeight) {
      return false;
    }

    return true;
  }