/// <summary>
/// Generates a path for the callout decoration, which is an isosceles triangle from the label's center pointing
/// to the node.
/// </summary>
/// <param name="label">The label for which to create the path.</param>
/// <returns>A path for the callout triangle.</returns>
private static GeneralPath GenerateTrianglePath(ILabel label)
{
var node = (INode)label.Owner;
var layout = label.GetLayout();
// Find the point where the triangle attaches to the outline shape
var outlineShape = node.Style.Renderer.GetShapeGeometry(node, node.Style).GetOutline();
var nodeCenter = node.Layout.GetCenter();
var labelCenter = layout.GetCenter();
if (outlineShape == null)
{
outlineShape = new GeneralPath(4);
outlineShape.AppendOrientedRectangle(layout, false);
}
var intersection = outlineShape.FindLineIntersection(nodeCenter, labelCenter);
var intersectionPoint = nodeCenter + intersection * (labelCenter - nodeCenter);
// Find the vector that is orthogonal to the line connecting the label and node centers
var triangleVector = labelCenter - intersectionPoint;
var orthoVector = OrthoNormal(triangleVector);
// Construct the other points of the triangle
var point2 = labelCenter + orthoVector * 20;
var point3 = labelCenter - orthoVector * 20;
// Create the path
var p = new GeneralPath();
p.MoveTo(intersectionPoint);
p.LineTo(point2);
p.LineTo(point3);
p.Close();
return(p);
}