performLayout method

@override Size performLayout(BoxConstraints constraints)

Hook for subclasses to perform layout within the given constraints.

Implementation

@override
Size performLayout(BoxConstraints constraints) {
  final split = widget as SplitPane;
  final w = constraints.maxWidth == BoxConstraints.infinity
      ? 20
      : constraints.maxWidth;
  final h = constraints.maxHeight == BoxConstraints.infinity
      ? 10
      : constraints.maxHeight;

  split._initLimits();
  final totalSize = split.direction == LayoutDirection.horizontal ? w : h;

  int dividerPos = _calculateDividerPos(totalSize);

  int minW1 = split._origMin1 ?? 0;
  int maxW1 = split._origMax1 ?? (totalSize - 1);
  if (split._origMin2 != null) {
    maxW1 = min(maxW1, totalSize - split._origMin2! - 1);
  }
  if (split._origMax2 != null) {
    minW1 = max(minW1, totalSize - split._origMax2! - 1);
  }
  minW1 = minW1.clamp(0, totalSize - 1);
  maxW1 = maxW1.clamp(0, totalSize - 1);
  if (minW1 > maxW1) minW1 = maxW1;

  dividerPos = dividerPos.clamp(minW1, maxW1);
  split._dividerX = dividerPos;

  if (split.direction == LayoutDirection.horizontal) {
    if (childElement1 != null) {
      childElement1!.relativeOffset = Offset.zero;
      if (dividerPos > 0) {
        childElement1!.layout(BoxConstraints.tight(Size(dividerPos, h)));
      }
    }
    if (childElement2 != null) {
      childElement2!.relativeOffset = Offset(dividerPos + 1, 0);
      final child2Width = w - dividerPos - 1;
      if (child2Width > 0) {
        childElement2!.layout(BoxConstraints.tight(Size(child2Width, h)));
      }
    }
  } else {
    if (childElement1 != null) {
      childElement1!.relativeOffset = Offset.zero;
      if (dividerPos > 0) {
        childElement1!.layout(BoxConstraints.tight(Size(w, dividerPos)));
      }
    }
    if (childElement2 != null) {
      childElement2!.relativeOffset = Offset(0, dividerPos + 1);
      final child2Height = h - dividerPos - 1;
      if (child2Height > 0) {
        childElement2!.layout(BoxConstraints.tight(Size(w, child2Height)));
      }
    }
  }

  return constraints.constrain(Size(w, h));
}