001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.data; 003 004import static org.openstreetmap.josm.tools.I18n.marktr; 005 006import java.text.NumberFormat; 007import java.util.Collections; 008import java.util.LinkedHashMap; 009import java.util.Locale; 010import java.util.Map; 011import java.util.Optional; 012import java.util.concurrent.CopyOnWriteArrayList; 013 014import org.openstreetmap.josm.data.preferences.StringProperty; 015import org.openstreetmap.josm.spi.preferences.Config; 016 017/** 018 * A system of units used to express length and area measurements. 019 * <p> 020 * This class also manages one globally set system of measurement stored in the {@code ProjectionPreference} 021 * @since 3406 (creation) 022 * @since 6992 (extraction in this package) 023 */ 024public class SystemOfMeasurement { 025 026 /** 027 * Preferences entry for system of measurement. 028 * @since 12674 (moved from ProjectionPreference) 029 */ 030 public static final StringProperty PROP_SYSTEM_OF_MEASUREMENT = new StringProperty("system_of_measurement", "Metric"); 031 032 /** 033 * Interface to notify listeners of the change of the system of measurement. 034 * @since 8554 035 * @since 10600 (functional interface) 036 */ 037 @FunctionalInterface 038 public interface SoMChangeListener { 039 /** 040 * The current SoM has changed. 041 * @param oldSoM The old system of measurement 042 * @param newSoM The new (current) system of measurement 043 */ 044 void systemOfMeasurementChanged(String oldSoM, String newSoM); 045 } 046 047 /** 048 * Metric system (international standard). 049 * @since 3406 050 */ 051 public static final SystemOfMeasurement METRIC = new SystemOfMeasurement(1, "m", 1000, "km", "km/h", 3.6, 10_000, "ha"); 052 053 /** 054 * Chinese system. 055 * See <a href="https://en.wikipedia.org/wiki/Chinese_units_of_measurement#Chinese_length_units_effective_in_1930">length units</a>, 056 * <a href="https://en.wikipedia.org/wiki/Chinese_units_of_measurement#Chinese_area_units_effective_in_1930">area units</a> 057 * @since 3406 058 */ 059 public static final SystemOfMeasurement CHINESE = new SystemOfMeasurement(1.0/3.0, "\u5e02\u5c3a" /* chi */, 500, "\u5e02\u91cc" /* li */, 060 "km/h", 3.6, 666.0 + 2.0/3.0, "\u4ea9" /* mu */); 061 062 /** 063 * Imperial system (British Commonwealth and former British Empire). 064 * @since 3406 065 */ 066 public static final SystemOfMeasurement IMPERIAL = new SystemOfMeasurement(0.3048, "ft", 1609.344, "mi", "mph", 2.23694, 4046.86, "ac"); 067 068 /** 069 * Nautical mile system (navigation, polar exploration). 070 * @since 5549 071 */ 072 public static final SystemOfMeasurement NAUTICAL_MILE = new SystemOfMeasurement(185.2, "kbl", 1852, "NM", "kn", 1.94384); 073 074 /** 075 * Known systems of measurement. 076 * @since 3406 077 */ 078 public static final Map<String, SystemOfMeasurement> ALL_SYSTEMS; 079 static { 080 Map<String, SystemOfMeasurement> map = new LinkedHashMap<>(); 081 map.put(marktr("Metric"), METRIC); 082 map.put(marktr("Chinese"), CHINESE); 083 map.put(marktr("Imperial"), IMPERIAL); 084 map.put(marktr("Nautical Mile"), NAUTICAL_MILE); 085 ALL_SYSTEMS = Collections.unmodifiableMap(map); 086 } 087 088 private static final CopyOnWriteArrayList<SoMChangeListener> somChangeListeners = new CopyOnWriteArrayList<>(); 089 090 /** 091 * Removes a global SoM change listener. 092 * 093 * @param listener the listener. Ignored if null or already absent 094 * @since 8554 095 */ 096 public static void removeSoMChangeListener(SoMChangeListener listener) { 097 somChangeListeners.remove(listener); 098 } 099 100 /** 101 * Adds a SoM change listener. 102 * 103 * @param listener the listener. Ignored if null or already registered. 104 * @since 8554 105 */ 106 public static void addSoMChangeListener(SoMChangeListener listener) { 107 if (listener != null) { 108 somChangeListeners.addIfAbsent(listener); 109 } 110 } 111 112 protected static void fireSoMChanged(String oldSoM, String newSoM) { 113 for (SoMChangeListener l : somChangeListeners) { 114 l.systemOfMeasurementChanged(oldSoM, newSoM); 115 } 116 } 117 118 /** 119 * Returns the current global system of measurement. 120 * @return The current system of measurement (metric system by default). 121 * @since 8554 122 */ 123 public static SystemOfMeasurement getSystemOfMeasurement() { 124 return Optional.ofNullable(SystemOfMeasurement.ALL_SYSTEMS.get(PROP_SYSTEM_OF_MEASUREMENT.get())) 125 .orElse(SystemOfMeasurement.METRIC); 126 } 127 128 /** 129 * Sets the current global system of measurement. 130 * @param somKey The system of measurement key. Must be defined in {@link SystemOfMeasurement#ALL_SYSTEMS}. 131 * @throws IllegalArgumentException if {@code somKey} is not known 132 * @since 8554 133 */ 134 public static void setSystemOfMeasurement(String somKey) { 135 if (!SystemOfMeasurement.ALL_SYSTEMS.containsKey(somKey)) { 136 throw new IllegalArgumentException("Invalid system of measurement: "+somKey); 137 } 138 String oldKey = PROP_SYSTEM_OF_MEASUREMENT.get(); 139 if (PROP_SYSTEM_OF_MEASUREMENT.put(somKey)) { 140 fireSoMChanged(oldKey, somKey); 141 } 142 } 143 144 /** First value, in meters, used to translate unit according to above formula. */ 145 public final double aValue; 146 /** Second value, in meters, used to translate unit according to above formula. */ 147 public final double bValue; 148 /** First unit used to format text. */ 149 public final String aName; 150 /** Second unit used to format text. */ 151 public final String bName; 152 /** Speed value for the most common speed symbol, in meters per second 153 * @since 10175 */ 154 public final double speedValue; 155 /** Most common speed symbol (kmh/h, mph, kn, etc.) 156 * @since 10175 */ 157 public final String speedName; 158 /** Specific optional area value, in squared meters, between {@code aValue*aValue} and {@code bValue*bValue}. Set to {@code -1} if not used. 159 * @since 5870 */ 160 public final double areaCustomValue; 161 /** Specific optional area unit. Set to {@code null} if not used. 162 * @since 5870 */ 163 public final String areaCustomName; 164 165 /** 166 * System of measurement. Currently covers only length (and area) units. 167 * 168 * If a quantity x is given in m (x_m) and in unit a (x_a) then it translates as 169 * x_a == x_m / aValue 170 * 171 * @param aValue First value, in meters, used to translate unit according to above formula. 172 * @param aName First unit used to format text. 173 * @param bValue Second value, in meters, used to translate unit according to above formula. 174 * @param bName Second unit used to format text. 175 * @param speedName the most common speed symbol (kmh/h, mph, kn, etc.) 176 * @param speedValue the speed value for the most common speed symbol, for 1 meter per second 177 * @since 10175 178 */ 179 public SystemOfMeasurement(double aValue, String aName, double bValue, String bName, String speedName, double speedValue) { 180 this(aValue, aName, bValue, bName, speedName, speedValue, -1, null); 181 } 182 183 /** 184 * System of measurement. Currently covers only length (and area) units. 185 * 186 * If a quantity x is given in m (x_m) and in unit a (x_a) then it translates as 187 * x_a == x_m / aValue 188 * 189 * @param aValue First value, in meters, used to translate unit according to above formula. 190 * @param aName First unit used to format text. 191 * @param bValue Second value, in meters, used to translate unit according to above formula. 192 * @param bName Second unit used to format text. 193 * @param speedName the most common speed symbol (kmh/h, mph, kn, etc.) 194 * @param speedValue the speed value for the most common speed symbol, for 1 meter per second 195 * @param areaCustomValue Specific optional area value, in squared meters, between {@code aValue*aValue} and {@code bValue*bValue}. 196 * Set to {@code -1} if not used. 197 * @param areaCustomName Specific optional area unit. Set to {@code null} if not used. 198 * 199 * @since 10175 200 */ 201 public SystemOfMeasurement(double aValue, String aName, double bValue, String bName, String speedName, double speedValue, 202 double areaCustomValue, String areaCustomName) { 203 this.aValue = aValue; 204 this.aName = aName; 205 this.bValue = bValue; 206 this.bName = bName; 207 this.speedValue = speedValue; 208 this.speedName = speedName; 209 this.areaCustomValue = areaCustomValue; 210 this.areaCustomName = areaCustomName; 211 } 212 213 /** 214 * Returns the text describing the given distance in this system of measurement. 215 * @param dist The distance in metres 216 * @return The text describing the given distance in this system of measurement. 217 */ 218 public String getDistText(double dist) { 219 return getDistText(dist, null, 0.01); 220 } 221 222 /** 223 * Returns the text describing the given distance in this system of measurement. 224 * @param dist The distance in metres 225 * @param format A {@link NumberFormat} to format the area value 226 * @param threshold Values lower than this {@code threshold} are displayed as {@code "< [threshold]"} 227 * @return The text describing the given distance in this system of measurement. 228 * @since 6422 229 */ 230 public String getDistText(final double dist, final NumberFormat format, final double threshold) { 231 double a = dist / aValue; 232 if (a > bValue / aValue && !Config.getPref().getBoolean("system_of_measurement.use_only_lower_unit", false)) 233 return formatText(dist / bValue, bName, format); 234 else if (a < threshold) 235 return "< " + formatText(threshold, aName, format); 236 else 237 return formatText(a, aName, format); 238 } 239 240 /** 241 * Returns the text describing the given area in this system of measurement. 242 * @param area The area in square metres 243 * @return The text describing the given area in this system of measurement. 244 * @since 5560 245 */ 246 public String getAreaText(double area) { 247 return getAreaText(area, null, 0.01); 248 } 249 250 /** 251 * Returns the text describing the given area in this system of measurement. 252 * @param area The area in square metres 253 * @param format A {@link NumberFormat} to format the area value 254 * @param threshold Values lower than this {@code threshold} are displayed as {@code "< [threshold]"} 255 * @return The text describing the given area in this system of measurement. 256 * @since 6422 257 */ 258 public String getAreaText(final double area, final NumberFormat format, final double threshold) { 259 double a = area / (aValue*aValue); 260 boolean lowerOnly = Config.getPref().getBoolean("system_of_measurement.use_only_lower_unit", false); 261 boolean customAreaOnly = Config.getPref().getBoolean("system_of_measurement.use_only_custom_area_unit", false); 262 if ((!lowerOnly && areaCustomValue > 0 && a > areaCustomValue / (aValue*aValue) 263 && a < (bValue*bValue) / (aValue*aValue)) || customAreaOnly) 264 return formatText(area / areaCustomValue, areaCustomName, format); 265 else if (!lowerOnly && a >= (bValue*bValue) / (aValue*aValue)) 266 return formatText(area / (bValue * bValue), bName + '\u00b2', format); 267 else if (a < threshold) 268 return "< " + formatText(threshold, aName + '\u00b2', format); 269 else 270 return formatText(a, aName + '\u00b2', format); 271 } 272 273 private static String formatText(double v, String unit, NumberFormat format) { 274 if (format != null) { 275 return format.format(v) + ' ' + unit; 276 } 277 return String.format(Locale.US, v < 9.999999 ? "%.2f %s" : "%.1f %s", v, unit); 278 } 279}