Class SweepLineEvent

1
2
3
4	/*
5	* Copyright (c) 2016 Vivid Solutions.
6	*
7	* All rights reserved. This program and the accompanying materials
8	* are made available under the terms of the Eclipse Public License 2.0
9	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
10	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
11	* and the Eclipse Distribution License is available at
12	*
13	* http://www.eclipse.org/org/documents/edl-v10.php.
14	*/
15	package org.locationtech.jts.geomgraph.index;
16
17	/**
18	* @version 1.7
19	*/
20	public class SweepLineEvent
21	implements Comparable
22	{
23	private static final int INSERT = 1;
24	private static final int DELETE = 2;
25
26	private Object label; // used for red-blue intersection detection
27	private double xValue;
28	private int eventType;
29	private SweepLineEvent insertEvent = null; // null if this is an INSERT event
30	private int deleteEventIndex;
31	private Object obj;
32
33	/**
34	* Creates an INSERT event.
35	*
36	* @param label the edge set label for this object
37	* @param x the event location
38	* @param obj the object being inserted
39	*/
40	public SweepLineEvent(Object label, double x, Object obj)
41	{
42	this.eventType = INSERT;
43	this.label = label;
44	xValue = x;
45	this.obj = obj;
46	}
47
48	/**
49	* Creates a DELETE event.
50	*
51	* @param x the event location
52	* @param insertEvent the corresponding INSERT event
53	*/
54	public SweepLineEvent(double x, SweepLineEvent insertEvent)
55	{
56	eventType = DELETE;
57	xValue = x;
58	this.insertEvent = insertEvent;
59	}
60
61	public boolean isInsert() { return eventType == INSERT; }
62	public boolean isDelete() { return eventType == DELETE; }
63	public SweepLineEvent getInsertEvent() { return insertEvent; }
64	public int getDeleteEventIndex() { return deleteEventIndex; }
65	public void setDeleteEventIndex(int deleteEventIndex) { this.deleteEventIndex = deleteEventIndex; }
66
67	public Object getObject() { return obj; }
68
69	public boolean isSameLabel(SweepLineEvent ev)
70	{
71	// no label set indicates single group
72	if (label == null) return false;
73	return label == ev.label;
74	}
75	/**
76	* Events are ordered first by their x-value, and then by their eventType.
77	* Insert events are sorted before Delete events, so that
78	* items whose Insert and Delete events occur at the same x-value will be
79	* correctly handled.
80	*/
81	public int compareTo(Object o) {
82	SweepLineEvent pe = (SweepLineEvent) o;
83	if (xValue < pe.xValue) return -1;
84	if (xValue > pe.xValue) return 1;
85	if (eventType < pe.eventType) return -1;
86	if (eventType > pe.eventType) return 1;
87	return 0;
88	}
89
90
91	}
92