1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.gui.mappaint.styleelement.placement;
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3 |
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4 | import java.awt.font.GlyphVector;
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5 | import java.awt.geom.AffineTransform;
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6 | import java.awt.geom.Rectangle2D;
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7 | import java.util.ArrayList;
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8 | import java.util.Collections;
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9 | import java.util.Comparator;
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10 | import java.util.Iterator;
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11 | import java.util.List;
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12 | import java.util.Optional;
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13 | import java.util.stream.IntStream;
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14 |
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15 | import org.openstreetmap.josm.gui.MapViewState.MapViewPoint;
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16 | import org.openstreetmap.josm.gui.draw.MapViewPath;
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17 | import org.openstreetmap.josm.gui.draw.MapViewPath.PathSegmentConsumer;
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18 | import org.openstreetmap.josm.gui.draw.MapViewPositionAndRotation;
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19 |
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20 | /**
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21 | * Places the label onto the line.
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22 | *
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23 | * @author Michael Zangl
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24 | * @since 11722
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25 | * @since 11748 moved to own file
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26 | */
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27 | public class OnLineStrategy implements PositionForAreaStrategy {
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28 | /**
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29 | * An instance of this class.
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30 | */
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31 | public static final OnLineStrategy INSTANCE = new OnLineStrategy(0);
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32 |
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33 | private final double yOffset;
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34 |
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35 | /**
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36 | * Create a new strategy that places the text on the line.
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37 | * @param yOffset The offset sidewards to the line.
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38 | */
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39 | public OnLineStrategy(double yOffset) {
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40 | this.yOffset = yOffset;
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41 | }
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42 |
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43 | @Override
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44 | public MapViewPositionAndRotation findLabelPlacement(MapViewPath path, Rectangle2D nb) {
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45 | return findOptimalWayPosition(nb, path).map(best -> {
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46 | MapViewPoint center = best.start.interpolate(best.end, .5);
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47 | return new MapViewPositionAndRotation(center, upsideTheta(best));
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48 | }).orElse(null);
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49 | }
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50 |
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51 | private static double upsideTheta(HalfSegment best) {
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52 | double theta = theta(best.start, best.end);
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53 | if (theta < -Math.PI / 2) {
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54 | return theta + Math.PI;
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55 | } else if (theta > Math.PI / 2) {
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56 | return theta - Math.PI;
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57 | } else {
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58 | return theta;
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59 | }
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60 | }
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61 |
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62 | @Override
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63 | public boolean supportsGlyphVector() {
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64 | return true;
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65 | }
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66 |
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67 | @Override
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68 | public List<GlyphVector> generateGlyphVectors(MapViewPath path, Rectangle2D nb, List<GlyphVector> gvs,
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69 | boolean isDoubleTranslationBug) {
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70 | // Find the position on the way the font should be placed.
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71 | // If none is found, use the middle of the way.
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72 | double middleOffset = findOptimalWayPosition(nb, path).map(segment -> segment.offset)
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73 | .orElse(path.getLength() / 2);
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74 |
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75 | // Check that segment of the way. Compute in which direction the text should be rendered.
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76 | // It is rendered in a way that ensures that at least 50% of the text are rotated with the right side up.
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77 | UpsideComputingVisitor upside = new UpsideComputingVisitor(middleOffset - nb.getWidth() / 2,
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78 | middleOffset + nb.getWidth() / 2);
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79 | path.visitLine(upside);
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80 | boolean doRotateText = upside.shouldRotateText();
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81 |
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82 | // Compute the list of glyphs to draw, along with their offset on the current line.
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83 | List<OffsetGlyph> offsetGlyphs = computeOffsetGlyphs(gvs,
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84 | middleOffset + (doRotateText ? 1 : -1) * nb.getWidth() / 2, doRotateText);
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85 |
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86 | // Order the glyphs along the line to ensure that they are drawn corretly.
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87 | Collections.sort(offsetGlyphs, Comparator.comparing(e -> e.offset));
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88 |
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89 | // Now translate all glyphs. This will modify the glyphs stored in gvs.
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90 | path.visitLine(new GlyphRotatingVisitor(offsetGlyphs, isDoubleTranslationBug));
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91 | return gvs;
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92 | }
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93 |
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94 | /**
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95 | * Create a list of glyphs with an offset along the way
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96 | * @param gvs The list of glyphs
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97 | * @param startOffset The offset in the line
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98 | * @param rotateText Rotate the text by 180°
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99 | * @return The list of glyphs.
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100 | */
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101 | private static List<OffsetGlyph> computeOffsetGlyphs(List<GlyphVector> gvs, double startOffset, boolean rotateText) {
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102 | double offset = startOffset;
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103 | ArrayList<OffsetGlyph> offsetGlyphs = new ArrayList<>();
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104 | for (GlyphVector gv : gvs) {
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105 | double gvOffset = offset;
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106 | IntStream.range(0, gv.getNumGlyphs())
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107 | .mapToObj(i -> new OffsetGlyph(gvOffset, rotateText, gv, i))
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108 | .forEach(offsetGlyphs::add);
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109 | offset += (rotateText ? -1 : 1) + gv.getLogicalBounds().getBounds2D().getWidth();
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110 | }
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111 | return offsetGlyphs;
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112 | }
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113 |
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114 | private static Optional<HalfSegment> findOptimalWayPosition(Rectangle2D rect, MapViewPath path) {
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115 | // find half segments that are long enough to draw text on (don't draw text over the cross hair in the center of each segment)
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116 | List<HalfSegment> longHalfSegment = new ArrayList<>();
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117 | double minSegmentLength = 2 * (rect.getWidth() + 4);
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118 | double length = path.visitLine((inLineOffset, start, end, startIsOldEnd) -> {
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119 | double segmentLength = start.distanceToInView(end);
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120 | if (segmentLength > minSegmentLength) {
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121 | MapViewPoint center = start.interpolate(end, .5);
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122 | double q = computeQuality(start, center);
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123 | // prefer the first one for quality equality.
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124 | longHalfSegment.add(new HalfSegment(start, center, q + .1, inLineOffset + .25 * segmentLength));
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125 |
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126 | q = computeQuality(center, end);
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127 | longHalfSegment.add(new HalfSegment(center, end, q, inLineOffset + .75 * segmentLength));
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128 | }
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129 | });
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130 |
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131 | // find the segment with the best quality. If there are several with best quality, the one close to the center is prefered.
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132 | return longHalfSegment.stream().max(
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133 | Comparator.comparingDouble(segment -> segment.quality - 1e-5 * Math.abs(segment.offset - length / 2)));
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134 | }
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135 |
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136 | private static double computeQuality(MapViewPoint p1, MapViewPoint p2) {
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137 | double q = 0;
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138 | if (p1.isInView()) {
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139 | q += 1;
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140 | }
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141 | if (p2.isInView()) {
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142 | q += 1;
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143 | }
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144 | return q;
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145 | }
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146 |
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147 | /**
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148 | * A half segment that can be used to place text on it. Used in the drawTextOnPath algorithm.
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149 | * @author Michael Zangl
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150 | */
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151 | private static class HalfSegment {
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152 | /**
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153 | * start point of half segment
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154 | */
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155 | private final MapViewPoint start;
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156 |
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157 | /**
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158 | * end point of half segment
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159 | */
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160 | private final MapViewPoint end;
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161 |
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162 | /**
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163 | * quality factor (off screen / partly on screen / fully on screen)
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164 | */
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165 | private final double quality;
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166 |
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167 | /**
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168 | * The offset in the path.
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169 | */
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170 | private final double offset;
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171 |
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172 | /**
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173 | * Create a new half segment
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174 | * @param start The start along the way
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175 | * @param end The end of the segment
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176 | * @param quality A quality factor.
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177 | * @param offset The offset in the path.
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178 | */
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179 | HalfSegment(MapViewPoint start, MapViewPoint end, double quality, double offset) {
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180 | super();
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181 | this.start = start;
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182 | this.end = end;
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183 | this.quality = quality;
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184 | this.offset = offset;
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185 | }
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186 |
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187 | @Override
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188 | public String toString() {
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189 | return "HalfSegment [start=" + start + ", end=" + end + ", quality=" + quality + "]";
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190 | }
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191 | }
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192 |
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193 | /**
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194 | * A visitor that computes the side of the way that is the upper one for each segment and computes the dominant upper side of the way.
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195 | * This is used to always place at least 50% of the text correctly.
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196 | */
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197 | private static class UpsideComputingVisitor implements PathSegmentConsumer {
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198 |
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199 | private final double startOffset;
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200 | private final double endOffset;
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201 |
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202 | private double upsideUpLines;
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203 | private double upsideDownLines;
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204 |
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205 | UpsideComputingVisitor(double startOffset, double endOffset) {
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206 | super();
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207 | this.startOffset = startOffset;
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208 | this.endOffset = endOffset;
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209 | }
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210 |
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211 | @Override
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212 | public void addLineBetween(double inLineOffset, MapViewPoint start, MapViewPoint end, boolean startIsOldEnd) {
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213 | if (inLineOffset > endOffset) {
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214 | return;
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215 | }
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216 | double length = start.distanceToInView(end);
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217 | if (inLineOffset + length < startOffset) {
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218 | return;
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219 | }
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220 |
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221 | double segmentStart = Math.max(inLineOffset, startOffset);
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222 | double segmentEnd = Math.min(inLineOffset + length, endOffset);
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223 |
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224 | double segmentLength = segmentEnd - segmentStart;
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225 |
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226 | if (start.getInViewX() < end.getInViewX()) {
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227 | upsideUpLines += segmentLength;
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228 | } else {
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229 | upsideDownLines += segmentLength;
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230 | }
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231 | }
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232 |
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233 | /**
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234 | * Check if the text should be rotated by 180°
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235 | * @return if the text should be rotated.
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236 | */
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237 | boolean shouldRotateText() {
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238 | return upsideUpLines < upsideDownLines;
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239 | }
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240 | }
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241 |
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242 | /**
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243 | * Rotate the glyphs along a path.
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244 | */
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245 | private class GlyphRotatingVisitor implements PathSegmentConsumer {
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246 | private final Iterator<OffsetGlyph> gvs;
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247 | private final boolean isDoubleTranslationBug;
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248 | private OffsetGlyph next;
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249 |
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250 | /**
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251 | * Create a new {@link GlyphRotatingVisitor}
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252 | * @param gvs The glyphs to draw. Sorted along the line
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253 | * @param isDoubleTranslationBug true to fix a double translation bug.
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254 | */
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255 | GlyphRotatingVisitor(List<OffsetGlyph> gvs, boolean isDoubleTranslationBug) {
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256 | this.isDoubleTranslationBug = isDoubleTranslationBug;
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257 | this.gvs = gvs.iterator();
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258 | takeNext();
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259 | while (next != null && next.offset < 0) {
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260 | // skip them
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261 | takeNext();
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262 | }
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263 | }
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264 |
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265 | private void takeNext() {
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266 | if (gvs.hasNext()) {
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267 | next = gvs.next();
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268 | } else {
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269 | next = null;
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270 | }
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271 | }
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272 |
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273 | @Override
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274 | public void addLineBetween(double inLineOffset, MapViewPoint start, MapViewPoint end, boolean startIsOldEnd) {
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275 | double segLength = start.distanceToInView(end);
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276 | double segEnd = inLineOffset + segLength;
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277 | double theta = theta(start, end);
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278 | while (next != null && next.offset < segEnd) {
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279 | Rectangle2D rect = next.getBounds();
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280 | double centerY = 0;
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281 | MapViewPoint p = start.interpolate(end, (next.offset - inLineOffset) / segLength);
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282 |
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283 | AffineTransform trfm = new AffineTransform();
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284 | trfm.translate(-rect.getCenterX(), -centerY);
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285 | trfm.translate(p.getInViewX(), p.getInViewY());
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286 | trfm.rotate(theta + next.preRotate, rect.getWidth() / 2, centerY);
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287 | trfm.translate(0, next.glyph.getFont().getSize2D() * .25);
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288 | trfm.translate(0, yOffset);
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289 | if (isDoubleTranslationBug) {
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290 | // scale the translation components by one half
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291 | AffineTransform tmp = AffineTransform.getTranslateInstance(-0.5 * trfm.getTranslateX(),
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292 | -0.5 * trfm.getTranslateY());
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293 | tmp.concatenate(trfm);
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294 | trfm = tmp;
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295 | }
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296 | next.glyph.setGlyphTransform(next.glyphIndex, trfm);
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297 | takeNext();
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298 | }
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299 | }
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300 | }
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301 |
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302 | private static class OffsetGlyph {
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303 | private final double offset;
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304 | private final double preRotate;
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305 | private final GlyphVector glyph;
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306 | private final int glyphIndex;
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307 |
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308 | OffsetGlyph(double offset, boolean rotateText, GlyphVector glyph, int glyphIndex) {
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309 | super();
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310 | this.preRotate = rotateText ? Math.PI : 0;
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311 | this.glyph = glyph;
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312 | this.glyphIndex = glyphIndex;
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313 | Rectangle2D rect = getBounds();
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314 | this.offset = offset + (rotateText ? -1 : 1) * (rect.getX() + rect.getWidth() / 2);
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315 | }
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316 |
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317 | private Rectangle2D getBounds() {
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318 | return glyph.getGlyphLogicalBounds(glyphIndex).getBounds2D();
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319 | }
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320 |
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321 | @Override
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322 | public String toString() {
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323 | return "OffsetGlyph [offset=" + offset + ", preRotate=" + preRotate + ", glyphIndex=" + glyphIndex + "]";
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324 | }
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325 |
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326 | }
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327 |
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328 | private static double theta(MapViewPoint start, MapViewPoint end) {
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329 | return Math.atan2(end.getInViewY() - start.getInViewY(), end.getInViewX() - start.getInViewX());
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330 | }
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331 | }
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