layoutEdges method

void layoutEdges(BoxConstraints constraints, SkillNodeLayout<NodeType, IdType> skillNodeLayout, GraphType graph, List<EdgeDetails<EdgeType, NodeType, IdType>> edgeChildrenDetails, List<NodeDetails<NodeType, IdType>> nodeChildrenDetails,)

We need to layout edges. However, an edge is not a direct RenderObject. Instead, it is a MultiChildRenderObject. Therefore, we must position the edges first based off the nodes.

The positions and sizes of both edge terminals are needed to layout this edge.

Implementation

void layoutEdges(
  BoxConstraints constraints,
  SkillNodeLayout<NodeType, IdType> skillNodeLayout,
  GraphType graph,
  List<EdgeDetails<EdgeType, NodeType, IdType>> edgeChildrenDetails,
  List<NodeDetails<NodeType, IdType>> nodeChildrenDetails,
) {
  for (final edgeDetails in edgeChildrenDetails) {
    // Get the necessary information of the nodes and edge data
    final edgeChild = edgeDetails.child;
    final edgeParentData = edgeDetails.parentData;
    final toDetails = nodeChildrenDetails.singleWhere((nodeDetails) {
      return nodeDetails.node.id == edgeDetails.edge.to;
    });
    final toChild = toDetails.child;
    final toParentData = toDetails.parentData;
    final toRect = toParentData.offset & toChild.size;
    final fromDetails = nodeChildrenDetails.singleWhere((nodeDetails) {
      return nodeDetails.node.id == edgeDetails.edge.from;
    });
    final fromChild = fromDetails.child;
    final fromParentData = fromDetails.parentData;
    final fromRect = fromParentData.offset & fromChild.size;

    assert(
      toRect.intersect(fromRect).isEmpty,
      'Two nodes must not intersect one another.',
    );

    /// Specify in a 2d space where the "to" Node is relative to the "from"
    /// node. (This will be used to orient the edge line and better draw
    /// the point).
    ///
    /// We get a vector moving from "from" to "to" and get the direction of the
    /// vector.
    final _toAlignment = edgeParentData.toAlignment ?? Alignment.center;
    final _fromAlignment = edgeParentData.fromAlignment ?? Alignment.center;
    final angle = (_toAlignment.withinRect(fromRect) -
            _fromAlignment.withinRect(toRect))
        .direction;
    final toAlignment =
        (edgeParentData.toAlignment ?? getAlignmentForAngle(angle));
    final fromAlignment = edgeParentData.fromAlignment ?? (toAlignment * -1);
    final fromCenter = fromAlignment.withinRect(fromRect);
    final toCenter = toAlignment.withinRect(toRect);

    // Laying out the individual points in the edge line
    Rect edgeBoundingBox = Rect.fromPoints(fromCenter, toCenter);
    final children = edgeChild.getChildrenAsList();

    final toEdgeChild = children.singleWhere((child) {
      return child.parentData is SkillPointToParentData;
    });
    final toEdgeChildParentData =
        toEdgeChild.parentData as SkillPointParentData;
    // TODO I shouldn't use getDryLayout here as it has some issues.
    // Do same as tooltip package.
    final toEdgeSize = toEdgeChild.getDryLayout(constraints);
    final toEdgeBox = toCenter.translate(
          -toEdgeSize.width / 2,
          -toEdgeSize.height / 2,
        ) &
        toEdgeSize;

    toEdgeChildParentData.rect = toEdgeBox.shift(-edgeBoundingBox.topLeft);

    final fromEdgeChild = children.singleWhere((child) {
      return child.parentData is SkillPointFromParentData;
    });
    final fromEdgeChildParentData =
        fromEdgeChild.parentData as SkillPointParentData;
    final fromEdgeSize = fromEdgeChild.getDryLayout(constraints);
    final fromEdgeBox = fromCenter.translate(
          -fromEdgeSize.width / 2,
          -fromEdgeSize.height / 2,
        ) &
        fromEdgeSize;

    fromEdgeChildParentData.rect = fromEdgeBox.shift(
      -edgeBoundingBox.topLeft,
    );

    edgeBoundingBox = edgeBoundingBox.expandToInclude(fromEdgeBox);

    edgeParentData.fromCenter = fromCenter - edgeBoundingBox.topLeft;
    edgeParentData.toCenter = toCenter - edgeBoundingBox.topLeft;

    // TODO We'll add control point sizes here
    // for (final controlPoint in controlPoints) {
    //   edgeBoundingBox.expandToInclude(fromEdgeBox);
    // }

    edgeParentData.offset = edgeBoundingBox.topLeft;

    // TODO I'm not setting the constraints properly yet because the current
    // boundingRect does not account for the gutter spacing. Gutter spacing
    // seems dependent on layout type too...
    // draggableEdgeChild.layout(BoxConstraints.tight(boundingRect.size));
    // TODO Prev todo might not be correct when dragging. A draggable should
    // not have constraints so it can reach even the furthest nodes.
    edgeChild.layout(constraints);
  }
}