1 | package org.expeditee.items;
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2 |
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3 | /**
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4 | * This class represents a constraint between two Dots on the screen. A vertical
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5 | * constraint means the Dot's Y values will be equal, likewise a horizontal
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6 | * constraint means the Dot's X values will be equal.
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7 | *
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8 | * @author jdm18
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9 | *
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10 | */
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11 | public class Constraint {
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12 | public static final int VERTICAL = 2;
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13 |
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14 | public static final int HORIZONTAL = 3;
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15 |
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16 | // the list of points that are constrained
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17 | private Item _start = null;
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18 |
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19 | private Item _end = null;
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20 |
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21 | // id and type info
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22 | private int _id;
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23 |
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24 | private int _type;
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25 |
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26 | /**
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27 | * Constructs a constraint with the two given end points, id, and type. Type
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28 | * should be one of the constants defined in this class.
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29 | *
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30 | * @param a
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31 | * One of the points in this constraint.
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32 | * @param b
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33 | * The other point in this constraint.
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34 | * @param id
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35 | * The ID of this constraint item.
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36 | * @param type
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37 | * The type of this constraint (horizontal, vertical).
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38 | */
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39 | public Constraint(Item a, Item b, int id, int type) {
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40 | _start = a;
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41 | _end = b;
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42 |
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43 | a.addConstraint(this);
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44 | b.addConstraint(this);
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45 |
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46 | _id = id;
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47 | _type = type;
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48 | }
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49 |
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50 | /**
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51 | * @return The Item ID of this Constraint.
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52 | */
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53 | public int getID() {
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54 | return _id;
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55 | }
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56 |
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57 | /**
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58 | *
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59 | * @return The type of this Constraint. The Type corresponds to the
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60 | * constants defined in this class.
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61 | */
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62 | public int getConstraintType() {
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63 | return _type;
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64 | }
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65 |
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66 | public Item getStart() {
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67 | return _start;
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68 | }
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69 |
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70 | public Item getEnd() {
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71 | return _end;
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72 | }
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73 |
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74 | public boolean contains(Item d) {
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75 | if (_start == d || _end == d)
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76 | return true;
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77 |
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78 | return false;
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79 | }
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80 |
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81 | /**
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82 | * If there are only two points in this constraint, this method returns the
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83 | * Point not passed to it. If there are more than two points then the first
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84 | * encountered is returned.
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85 | *
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86 | * @return A Point in the constraint that is not the one given (or null if
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87 | * none is found).
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88 | */
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89 | public Item getOppositeEnd(Item from) {
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90 | if (from == _start)
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91 | return _end;
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92 |
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93 | if (from == _end)
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94 | return _start;
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95 |
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96 | return null;
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97 | }
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98 |
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99 | public void replacePoint(Dot toReplace, Dot with) {
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100 | if (_start == toReplace)
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101 | _start = with;
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102 |
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103 | if (_end == toReplace)
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104 | _end = with;
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105 | }
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106 |
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107 | public String getLineEnds() {
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108 | String ends = "";
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109 |
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110 | if (_start != null)
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111 | ends += _start.getID();
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112 |
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113 | if (_end != null)
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114 | ends += " " + _end.getID();
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115 |
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116 | return ends;
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117 | }
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118 |
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119 | }
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