Function computePanelCellSizes

packages/core/src/widgets/splitPane.ts:142–196

(
  panelCount: number,
  sizes: readonly number[],
  available: number,
  sizeMode: "percent" | "absolute",
  dividerSize: number = DEFAULT_DIVIDER_SIZE,
  minSizes?: readonly number[],
  maxSizes?: readonly number[],
)

 * @param maxSizes - Maximum sizes per panel (cells)
 */
export function computePanelCellSizes(
  panelCount: number,
  sizes: readonly number[],
  available: number,
  sizeMode: "percent" | "absolute",
  dividerSize: number = DEFAULT_DIVIDER_SIZE,
  minSizes?: readonly number[],
  maxSizes?: readonly number[],
): PanelSizes {
  if (panelCount <= 0) {
    return Object.freeze({ sizes: Object.freeze([]), dividerPositions: Object.freeze([]) });
  }

  const totalDividerSpace = Math.max(0, panelCount - 1) * dividerSize;
  const availableForPanels = Math.max(0, available - totalDividerSpace);

  const cellSizes = new Array<number>(panelCount);
  const percentWeights = new Array<number>(panelCount).fill(0);
  for (let i = 0; i < panelCount; i++) {
    const rawSizeSpec = sizes[i];
    const sizeSpec = Number.isFinite(rawSizeSpec)
      ? (rawSizeSpec as number)
      : sizeMode === "percent"
        ? 100 / panelCount
        : Math.floor(availableForPanels / panelCount);

    if (sizeMode === "percent") {
      percentWeights[i] = sizeSpec > 0 ? sizeSpec : 0;
    } else {
      cellSizes[i] = Math.max(0, Math.trunc(sizeSpec));
    }
  }

  if (sizeMode === "percent") {
    const distributed = distributeInteger(availableForPanels, percentWeights);
    for (let i = 0; i < panelCount; i++) {
      cellSizes[i] = distributed[i] ?? 0;
    }
  }

  normalizePanelCellSizes(cellSizes, availableForPanels, minSizes, maxSizes);

  const dividerPositions: number[] = [];
  let position = 0;
  for (let j = 0; j < cellSizes.length - 1; j++) {
    position += cellSizes[j] ?? 0;
    dividerPositions.push(position);
    position += dividerSize;
  }

  return Object.freeze({
    sizes: Object.freeze(cellSizes),
    dividerPositions: Object.freeze(dividerPositions),
  });
}

/**
 * Handle divider drag to resize panels.