[919] | 1 | /**
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| 2 | * Constraint.java
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| 3 | * Copyright (C) 2010 New Zealand Digital Library, http://expeditee.org
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| 4 | *
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| 5 | * This program is free software: you can redistribute it and/or modify
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| 6 | * it under the terms of the GNU General Public License as published by
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| 7 | * the Free Software Foundation, either version 3 of the License, or
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| 8 | * (at your option) any later version.
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| 9 | *
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| 10 | * This program is distributed in the hope that it will be useful,
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| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | * GNU General Public License for more details.
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| 14 | *
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| 15 | * You should have received a copy of the GNU General Public License
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| 16 | * along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 17 | */
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| 18 |
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[4] | 19 | package org.expeditee.items;
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| 20 |
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| 21 | /**
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| 22 | * This class represents a constraint between two Dots on the screen. A vertical
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| 23 | * constraint means the Dot's Y values will be equal, likewise a horizontal
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| 24 | * constraint means the Dot's X values will be equal.
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| 25 | *
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| 26 | * @author jdm18
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| 27 | *
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| 28 | */
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| 29 | public class Constraint {
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| 30 | public static final int VERTICAL = 2;
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| 31 |
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| 32 | public static final int HORIZONTAL = 3;
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[97] | 33 |
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| 34 | public static final int DIAGONAL_POS = 4;
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| 35 |
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| 36 | public static final int DIAGONAL_NEG = 5;
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[4] | 37 |
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| 38 | // the list of points that are constrained
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| 39 | private Item _start = null;
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| 40 |
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| 41 | private Item _end = null;
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| 42 |
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| 43 | // id and type info
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| 44 | private int _id;
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| 45 |
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| 46 | private int _type;
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| 47 |
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| 48 | /**
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| 49 | * Constructs a constraint with the two given end points, id, and type. Type
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| 50 | * should be one of the constants defined in this class.
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| 51 | *
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| 52 | * @param a
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| 53 | * One of the points in this constraint.
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| 54 | * @param b
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| 55 | * The other point in this constraint.
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| 56 | * @param id
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| 57 | * The ID of this constraint item.
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| 58 | * @param type
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| 59 | * The type of this constraint (horizontal, vertical).
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| 60 | */
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| 61 | public Constraint(Item a, Item b, int id, int type) {
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| 62 | _start = a;
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| 63 | _end = b;
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| 64 |
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| 65 | a.addConstraint(this);
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| 66 | b.addConstraint(this);
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| 67 |
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| 68 | _id = id;
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| 69 | _type = type;
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| 70 | }
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| 71 |
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| 72 | /**
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| 73 | * @return The Item ID of this Constraint.
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| 74 | */
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| 75 | public int getID() {
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| 76 | return _id;
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| 77 | }
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| 78 |
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| 79 | /**
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| 80 | *
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| 81 | * @return The type of this Constraint. The Type corresponds to the
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| 82 | * constants defined in this class.
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| 83 | */
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[50] | 84 | public int getType() {
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[4] | 85 | return _type;
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| 86 | }
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| 87 |
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| 88 | public Item getStart() {
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| 89 | return _start;
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| 90 | }
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| 91 |
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| 92 | public Item getEnd() {
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| 93 | return _end;
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| 94 | }
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| 95 |
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[50] | 96 | public boolean contains(Item i) {
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| 97 | if (_start == i || _end == i)
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[4] | 98 | return true;
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| 99 |
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| 100 | return false;
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| 101 | }
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| 102 |
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| 103 | /**
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| 104 | * If there are only two points in this constraint, this method returns the
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| 105 | * Point not passed to it. If there are more than two points then the first
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| 106 | * encountered is returned.
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| 107 | *
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| 108 | * @return A Point in the constraint that is not the one given (or null if
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| 109 | * none is found).
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| 110 | */
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| 111 | public Item getOppositeEnd(Item from) {
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| 112 | if (from == _start)
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| 113 | return _end;
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| 114 |
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| 115 | if (from == _end)
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| 116 | return _start;
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| 117 |
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| 118 | return null;
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| 119 | }
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| 120 |
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[50] | 121 | public void replaceEnd(Item toReplace, Item with) {
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| 122 | assert(_start != _end);
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| 123 | if (_start == toReplace) {
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[4] | 124 | _start = with;
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[50] | 125 | } else if (_end == toReplace) {
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[4] | 126 | _end = with;
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[50] | 127 | }
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| 128 | toReplace.removeConstraint(this);
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| 129 | with.addConstraint(this);
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[4] | 130 | }
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| 131 |
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| 132 | public String getLineEnds() {
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| 133 | String ends = "";
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| 134 |
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| 135 | if (_start != null)
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| 136 | ends += _start.getID();
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| 137 |
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| 138 | if (_end != null)
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| 139 | ends += " " + _end.getID();
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| 140 |
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| 141 | return ends;
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| 142 | }
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| 143 |
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[97] | 144 | public boolean isDiagonal() {
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| 145 | return _type == Constraint.DIAGONAL_NEG || _type == Constraint.DIAGONAL_POS;
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| 146 | }
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| 147 |
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| 148 | public Float getGradient() {
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| 149 | switch(_type){
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| 150 | case Constraint.DIAGONAL_NEG:
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| 151 | return -1.0F;
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| 152 | case Constraint.DIAGONAL_POS:
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| 153 | return 1.0F;
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| 154 | case Constraint.HORIZONTAL:
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| 155 | return 0.0F;
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| 156 | case Constraint.VERTICAL:
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| 157 | return Float.POSITIVE_INFINITY;
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| 158 | }
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| 159 | assert(false);
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| 160 | return null;
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| 161 | }
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| 162 |
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[4] | 163 | }
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