handleMouseEvent method

@override void handleMouseEvent(MouseEvent event, int localX, int localY)

Intercepts mouse drag/press events over the divider.

Implementation

@override
void handleMouseEvent(MouseEvent event, int localX, int localY) {
  final split = widget as SplitPane;
  if (split._lastArea == null) return;
  split._initLimits();
  final totalSize = split.direction == LayoutDirection.horizontal
      ? split._lastArea!.width
      : split._lastArea!.height;
  if (totalSize <= 0) return;

  final mousePos = split.direction == LayoutDirection.horizontal
      ? localX
      : localY;

  if (event.type == MouseEventType.press) {
    if (mousePos == split._dividerX) {
      split._isDragging = true;
    }
  } else if (event.type == MouseEventType.release) {
    split._isDragging = false;
  } else if (event.type == MouseEventType.drag && split._isDragging) {
    int newDividerPos = mousePos;

    // Solve bounds/limits
    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;

    newDividerPos = newDividerPos.clamp(minW1, maxW1);

    // Mutate constraints in place
    final c1 = split.constraint1;
    if (c1 is LengthConstraint) {
      split.constraint1 = LengthConstraint(newDividerPos);
      split.constraint2 = LengthConstraint(totalSize - newDividerPos - 1);
    } else if (c1 is PercentageConstraint) {
      final p1 = (newDividerPos * 100 / totalSize).round().clamp(0, 100);
      split.constraint1 = PercentageConstraint(p1);
      split.constraint2 = PercentageConstraint(100 - p1);
    } else if (c1 is FlexConstraint) {
      split.constraint1 = FlexConstraint(newDividerPos);
      split.constraint2 = FlexConstraint(totalSize - newDividerPos - 1);
    } else if (c1 is MinMaxConstraint) {
      // Here we keep the min limits but update the current value via a new MinMaxConstraint.
      // Wait, since MinMaxConstraint uses min to represent the preferred size, we update the min.
      // But the original min limit is stored in _origMin1, so we still clamp correctly.
      split.constraint1 = MinMaxConstraint(
        min: newDividerPos,
        max: split._origMax1 ?? 99999,
      );
      if (split.constraint2 is MinMaxConstraint) {
        split.constraint2 = MinMaxConstraint(
          min: totalSize - newDividerPos - 1,
          max: split._origMax2 ?? 99999,
        );
      } else {
        split.constraint2 = MinMaxConstraint(
          min: totalSize - newDividerPos - 1,
        );
      }
    }
    split._dividerX = newDividerPos;
  }
}