Function ensureDataZoomSliderHost

src/ChartGPU.ts:664–689

()

  const DATA_ZOOM_SLIDER_RESERVE_CSS_PX = DATA_ZOOM_SLIDER_HEIGHT_CSS_PX + DATA_ZOOM_SLIDER_MARGIN_TOP_CSS_PX;

  const ensureDataZoomSliderHost = (): HTMLDivElement => {
    if (dataZoomSliderHost) return dataZoomSliderHost;

    // Ensure the host's absolute positioning is anchored to the chart container.
    // If the container is already positioned, avoid overwriting user styles.
    try {
      const pos = window.getComputedStyle(container).position;
      if (pos === 'static') container.style.position = 'relative';
    } catch {
      // best-effort
    }

    const host = document.createElement('div');
    host.style.position = 'absolute';
    host.style.left = '0';
    host.style.right = '0';
    host.style.bottom = '0';
    host.style.height = `${DATA_ZOOM_SLIDER_RESERVE_CSS_PX}px`;
    host.style.paddingTop = `${DATA_ZOOM_SLIDER_MARGIN_TOP_CSS_PX}px`;
    host.style.boxSizing = 'border-box';
    host.style.pointerEvents = 'auto';
    host.style.zIndex = '5';
    container.appendChild(host);
    dataZoomSliderHost = host;
    return host;
  };

  const computeZoomInOutAnchorRatio = (range: ZoomRange, center: number): number => {
    const span = range.end - range.start;