8f7a0b2a167bf9e40cb9b81635757a657941d920
1 /**
2 * \file
3 * \brief Simple closed interval class
4 *
5 * Copyright 2007 Michael Sloan <mgsloan@gmail.com>
6 *
7 * Original Rect/Range code by:
8 * Lauris Kaplinski <lauris@kaplinski.com>
9 * Nathan Hurst <njh@mail.csse.monash.edu.au>
10 * bulia byak <buliabyak@users.sf.net>
11 * MenTaLguY <mental@rydia.net>
12 *
13 * This library is free software; you can redistribute it and/or
14 * modify it either under the terms of the GNU Lesser General Public
15 * License version 2.1 as published by the Free Software Foundation
16 * (the "LGPL") or, at your option, under the terms of the Mozilla
17 * Public License Version 1.1 (the "MPL"). If you do not alter this
18 * notice, a recipient may use your version of this file under either
19 * the MPL or the LGPL.
20 *
21 * You should have received a copy of the LGPL along with this library
22 * in the file COPYING-LGPL-2.1; if not, output to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 * You should have received a copy of the MPL along with this library
25 * in the file COPYING-MPL-1.1
26 *
27 * The contents of this file are subject to the Mozilla Public License
28 * Version 1.1 (the "License"); you may not use this file except in
29 * compliance with the License. You may obtain a copy of the License at
30 * http://www.mozilla.org/MPL/
31 *
32 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
33 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
34 * the specific language governing rights and limitations.
35 *
36 */
37 #ifndef SEEN_INTERVAL_H
38 #define SEEN_INTERVAL_H
40 #include <assert.h>
41 #include <2geom/coord.h>
43 #include <boost/optional/optional.hpp>
45 namespace Geom {
47 /* Although an Interval where _b[0] > _b[1] is considered empty, for proper functioning of other methods,
48 * a proper empty Interval is [+infinity, -infinity]. Then, expandTo(p) will set the interval to [p,p].
49 */
50 class Interval {
51 private:
52 Coord _b[2];
54 public:
55 // The default constructor creates an empty interval, that ranges from +infinity to -infinity.
56 // Doing an expandTo(p) on this empty interval will correctly set the whole interval to [p,p].
57 explicit Interval() { _b[0] = +infinity(); _b[1] = -infinity(); }
58 explicit Interval(Coord u) { _b[0] = _b[1] = u; }
59 /* When creating an Interval using the constructor specifying the exact range, the created interval
60 * will be [u,v] when u<=v ; and will be [v,u] when v < u !!!
61 */
62 Interval(Coord u, Coord v) {
63 if(u < v) {
64 _b[0] = u; _b[1] = v;
65 } else {
66 _b[0] = v; _b[1] = u;
67 }
68 }
70 double operator[](unsigned i) const {
71 assert(i < 2);
72 return _b[i];
73 }
74 inline double& operator[](unsigned i) { return _b[i]; } //Trust the user...
76 inline Coord min() const { return _b[0]; }
77 inline Coord max() const { return _b[1]; }
78 inline Coord extent() const { return _b[1] - _b[0]; }
79 inline Coord middle() const { return (_b[1] + _b[0]) * 0.5; }
81 inline bool isEmpty() const { return _b[0] > _b[1]; }
82 inline bool contains(Coord val) const { return _b[0] <= val && val <= _b[1]; }
83 bool contains(const Interval & val) const { return _b[0] <= val._b[0] && val._b[1] <= _b[1]; }
84 bool intersects(const Interval & val) const {
85 return contains(val._b[0]) || contains(val._b[1]) || val.contains(*this);
86 }
88 inline bool operator==(Interval other) const { return _b[0] == other._b[0] && _b[1] == other._b[1]; }
89 inline bool operator!=(Interval other) const { return _b[0] != other._b[0] || _b[1] != other._b[1]; }
91 //IMPL: OffsetableConcept
92 //TODO: rename output_type to something else in the concept
93 typedef Coord output_type;
94 inline Interval operator+(Coord amnt) {
95 return Interval(_b[0] + amnt, _b[1] + amnt);
96 }
97 inline Interval operator-(Coord amnt) {
98 return Interval(_b[0] - amnt, _b[1] - amnt);
99 }
100 inline Interval operator+=(Coord amnt) {
101 _b[0] += amnt; _b[1] += amnt;
102 return *this;
103 }
104 inline Interval operator-=(Coord amnt) {
105 _b[0] -= amnt; _b[1] -= amnt;
106 return *this;
107 }
109 //IMPL: ScalableConcept
110 inline Interval operator-() const { return Interval(*this); }
111 inline Interval operator*(Coord s) const { return Interval(_b[0]*s, _b[1]*s); }
112 inline Interval operator/(Coord s) const { return Interval(_b[0]/s, _b[1]/s); }
113 Interval operator*=(Coord s) {
114 if(s < 0) {
115 Coord temp = _b[0];
116 _b[0] = _b[1]*s;
117 _b[1] = temp*s;
118 } else {
119 _b[0] *= s;
120 _b[1] *= s;
121 }
122 return *this;
123 }
124 Interval operator/=(Coord s) {
125 //TODO: what about s=0?
126 if(s < 0) {
127 Coord temp = _b[0];
128 _b[0] = _b[1]/s;
129 _b[1] = temp/s;
130 } else {
131 _b[0] /= s;
132 _b[1] /= s;
133 }
134 return *this;
135 }
137 //TODO: NaN handleage for the next two?
138 //TODO: Evaluate if wrap behaviour is proper.
139 //If val > max, then rather than becoming a min==max range, it 'wraps' over
140 void setMin(Coord val) {
141 if(val > _b[1]) {
142 _b[0] = _b[1];
143 _b[1] = val;
144 } else {
145 _b[0] = val;
146 }
147 }
148 //If val < min, then rather than becoming a min==max range, it 'wraps' over
149 void setMax(Coord val) {
150 if(val < _b[0]) {
151 _b[1] = _b[0];
152 _b[0] = val;
153 } else {
154 _b[1] = val;
155 }
156 }
158 inline void extendTo(Coord val) {
159 if(val < _b[0]) _b[0] = val;
160 if(val > _b[1]) _b[1] = val; //no else, as we want to handle NaN
161 }
163 static Interval fromArray(const Coord* c, int n) {
164 assert(n > 0);
165 Interval result(c[0]);
166 for(int i = 1; i < n; i++) result.extendTo(c[i]);
167 return result;
168 }
170 inline void expandBy(double amnt) {
171 _b[0] -= amnt;
172 _b[1] += amnt;
173 }
175 inline void unionWith(const Interval & a) {
176 if(a._b[0] < _b[0]) _b[0] = a._b[0];
177 if(a._b[1] > _b[1]) _b[1] = a._b[1];
178 }
179 };
181 //IMPL: AddableConcept
182 inline Interval operator+(const Interval & a, const Interval & b) {
183 return Interval(a.min() + b.min(), a.max() + b.max());
184 }
185 inline Interval operator-(const Interval & a, const Interval & b) {
186 return Interval(a.min() - b.max(), a.max() - b.min());
187 }
188 inline Interval operator+=(Interval & a, const Interval & b) { a = a + b; return a; }
189 inline Interval operator-=(Interval & a, const Interval & b) { a = a - b; return a; }
191 //There might be impls of this based off sign checks
192 inline Interval operator*(const Interval & a, const Interval & b) {
193 Interval res(a.min() * b.min());
194 res.extendTo(a.min() * b.max());
195 res.extendTo(a.max() * b.min());
196 res.extendTo(a.max() * b.max());
197 return res;
198 }
199 inline Interval operator*=(Interval & a, const Interval & b) { a = a * b; return a; }
201 /* reinstate if useful (doesn't do the proper thing for 0 inclusion)
202 inline Interval operator/(const Interval & a, const Interval & b) {
203 Interval res(a.min() / b.min());
204 res.extendTo(a.min() / b.max());
205 res.extendTo(a.max() / b.min());
206 res.extendTo(a.max() / b.max());
207 return res;
208 }
209 inline Interval operator/=(Interval & a, const Interval & b) { a = a / b; return a; }
210 */
212 // 'union' conflicts with C keyword
213 inline Interval unify(const Interval & a, const Interval & b) {
214 return Interval(std::min(a.min(), b.min()),
215 std::max(a.max(), b.max()));
216 }
217 inline boost::optional<Interval> intersect(const Interval & a, const Interval & b) {
218 Coord u = std::max(a.min(), b.min()),
219 v = std::min(a.max(), b.max());
220 //technically >= might be incorrect, but singulars suck
221 return u >= v ? boost::optional<Interval>()
222 : boost::optional<Interval>(Interval(u, v));
223 }
225 }
226 #endif //SEEN_INTERVAL_H
228 /*
229 Local Variables:
230 mode:c++
231 c-file-style:"stroustrup"
232 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
233 indent-tabs-mode:nil
234 fill-column:99
235 End:
236 */
237 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :