render method

@override void render(Canvas canvas, Graph graph, Paint paint)

Implementation

@override
void render(Canvas canvas, Graph graph, Paint paint) {
  var levelSeparationHalf = configuration.levelSeparation / 2;

  graph.nodes.forEach((node) {
    var children = graph.successorsOf(node);

    children.forEach((child) {
      var edge = graph.getEdgeBetween(node, child);
      var edgePaint = (edge?.paint ?? paint)..style = PaintingStyle.stroke;
      linePath.reset();
      switch (configuration.orientation) {
        case BuchheimWalkerConfiguration.ORIENTATION_TOP_BOTTOM:
          // position at the middle-top of the child
          linePath.moveTo((child.x + child.width / 2), child.y);
          // draws a line from the child's middle-top halfway up to its parent
          linePath.lineTo(child.x + child.width / 2, child.y - levelSeparationHalf);
          // draws a line from the previous point to the middle of the parents width
          linePath.lineTo(node.x + node.width / 2, child.y - levelSeparationHalf);

          // position at the middle of the level separation under the parent
          linePath.moveTo(node.x + node.width / 2, child.y - levelSeparationHalf);
          // draws a line up to the parents middle-bottom
          linePath.lineTo(node.x + node.width / 2, node.y + node.height);

          break;
        case BuchheimWalkerConfiguration.ORIENTATION_BOTTOM_TOP:
          linePath.moveTo(child.x + child.width / 2, child.y + child.height);
          linePath.lineTo(child.x + child.width / 2, child.y + child.height + levelSeparationHalf);
          linePath.lineTo(node.x + node.width / 2, child.y + child.height + levelSeparationHalf);

          linePath.moveTo(node.x + node.width / 2, child.y + child.height + levelSeparationHalf);
          linePath.lineTo(node.x + node.width / 2, node.y + node.height);

          break;
        case BuchheimWalkerConfiguration.ORIENTATION_LEFT_RIGHT:
          linePath.moveTo(child.x, child.y + child.height / 2);
          linePath.lineTo(child.x - levelSeparationHalf, child.y + child.height / 2);
          linePath.lineTo(child.x - levelSeparationHalf, node.y + node.height / 2);

          linePath.moveTo(child.x - levelSeparationHalf, node.y + node.height / 2);
          linePath.lineTo(node.x + node.width, node.y + node.height / 2);

          break;
        case BuchheimWalkerConfiguration.ORIENTATION_RIGHT_LEFT:
          linePath.moveTo(child.x + child.width, child.y + child.height / 2);
          linePath.lineTo(child.x + child.width + levelSeparationHalf, child.y + child.height / 2);
          linePath.lineTo(child.x + child.width + levelSeparationHalf, node.y + node.height / 2);

          linePath.moveTo(child.x + child.width + levelSeparationHalf, node.y + node.height / 2);
          linePath.lineTo(node.x + node.width, node.y + node.height / 2);
      }

      canvas.drawPath(linePath, edgePaint);
    });
  });
}