Zigzag.java

/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2020, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
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 * Original Author:  Arnaud Roques
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package net.sourceforge.plantuml.ebnf;

import net.sourceforge.plantuml.klimt.UPath;

public class Zigzag {

	private final double width;
	private final double height;
	private final double ctrl;

	public Zigzag(double ctrl, double width, double height) {
		this.ctrl = ctrl;
		this.width = width;
		this.height = height;
	}

	public UPath pathDown() {
		final UPath path = UPath.none();
		final double xm = width / 2;
		final double ym = height / 2;

		path.moveTo(0, 0);

		final double cp1x1 = ctrl;
		final double cp1y1 = 0;
		final double cp1x2 = xm;
		final double cp1y2 = ym - ctrl;
		path.cubicTo(cp1x1, cp1y1, cp1x2, cp1y2, xm, ym);

		final double cp2x1 = xm;
		final double cp2y1 = ym + ctrl;
		final double cp2x2 = width - ctrl;
		final double cp2y2 = height;
		path.cubicTo(cp2x1, cp2y1, cp2x2, cp2y2, width, height);

		return path;
	}

	public UPath pathUp() {
		final UPath path = UPath.none();
		final double xm = width / 2;
		final double ym = height / 2;

		path.moveTo(0, height);

		final double cp1x1 = ctrl;
		final double cp1y1 = height;
		final double cp1x2 = xm;
		final double cp1y2 = ym + ctrl;
		path.cubicTo(cp1x1, cp1y1, cp1x2, cp1y2, xm, ym);

		final double cp2x1 = xm;
		final double cp2y1 = ym - ctrl;
		final double cp2x2 = width - ctrl;
		final double cp2y2 = 0;
		path.cubicTo(cp2x1, cp2y1, cp2x2, cp2y2, width, 0);
		
		return path;
	}

}