// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.data;
import static org.openstreetmap.josm.tools.I18n.marktr;
import java.text.NumberFormat;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.CopyOnWriteArrayList;
import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.gui.preferences.projection.ProjectionPreference;
/**
* A system of units used to express length and area measurements.
* <p>
* This class also manages one globally set system of measurement stored in the {@link ProjectionPreference}
* @since 3406 (creation)
* @since 6992 (extraction in this package)
*/
public class SystemOfMeasurement {
/**
* Interface to notify listeners of the change of the system of measurement.
* @since 8554
* @since 10600 (functional interface)
*/
@FunctionalInterface
public interface SoMChangeListener {
/**
* The current SoM has changed.
* @param oldSoM The old system of measurement
* @param newSoM The new (current) system of measurement
*/
void systemOfMeasurementChanged(String oldSoM, String newSoM);
}
/**
* Metric system (international standard).
* @since 3406
*/
public static final SystemOfMeasurement METRIC = new SystemOfMeasurement(1, "m", 1000, "km", "km/h", 3.6, 10_000, "ha");
/**
* Chinese system.
* See <a href="https://en.wikipedia.org/wiki/Chinese_units_of_measurement#Chinese_length_units_effective_in_1930">length units</a>,
* <a href="https://en.wikipedia.org/wiki/Chinese_units_of_measurement#Chinese_area_units_effective_in_1930">area units</a>
* @since 3406
*/
public static final SystemOfMeasurement CHINESE = new SystemOfMeasurement(1.0/3.0, "\u5e02\u5c3a" /* chi */, 500, "\u5e02\u91cc" /* li */,
"km/h", 3.6, 666.0 + 2.0/3.0, "\u4ea9" /* mu */);
/**
* Imperial system (British Commonwealth and former British Empire).
* @since 3406
*/
public static final SystemOfMeasurement IMPERIAL = new SystemOfMeasurement(0.3048, "ft", 1609.344, "mi", "mph", 2.23694, 4046.86, "ac");
/**
* Nautical mile system (navigation, polar exploration).
* @since 5549
*/
public static final SystemOfMeasurement NAUTICAL_MILE = new SystemOfMeasurement(185.2, "kbl", 1852, "NM", "kn", 1.94384);
/**
* Known systems of measurement.
* @since 3406
*/
public static final Map<String, SystemOfMeasurement> ALL_SYSTEMS;
static {
Map<String, SystemOfMeasurement> map = new LinkedHashMap<>();
map.put(marktr("Metric"), METRIC);
map.put(marktr("Chinese"), CHINESE);
map.put(marktr("Imperial"), IMPERIAL);
map.put(marktr("Nautical Mile"), NAUTICAL_MILE);
ALL_SYSTEMS = Collections.unmodifiableMap(map);
}
private static final CopyOnWriteArrayList<SoMChangeListener> somChangeListeners = new CopyOnWriteArrayList<>();
/**
* Removes a global SoM change listener.
*
* @param listener the listener. Ignored if null or already absent
* @since 8554
*/
public static void removeSoMChangeListener(SoMChangeListener listener) {
somChangeListeners.remove(listener);
}
/**
* Adds a SoM change listener.
*
* @param listener the listener. Ignored if null or already registered.
* @since 8554
*/
public static void addSoMChangeListener(SoMChangeListener listener) {
if (listener != null) {
somChangeListeners.addIfAbsent(listener);
}
}
protected static void fireSoMChanged(String oldSoM, String newSoM) {
for (SoMChangeListener l : somChangeListeners) {
l.systemOfMeasurementChanged(oldSoM, newSoM);
}
}
/**
* Returns the current global system of measurement.
* @return The current system of measurement (metric system by default).
* @since 8554
*/
public static SystemOfMeasurement getSystemOfMeasurement() {
return Optional.ofNullable(SystemOfMeasurement.ALL_SYSTEMS.get(ProjectionPreference.PROP_SYSTEM_OF_MEASUREMENT.get()))
.orElse(SystemOfMeasurement.METRIC);
}
/**
* Sets the current global system of measurement.
* @param somKey The system of measurement key. Must be defined in {@link SystemOfMeasurement#ALL_SYSTEMS}.
* @throws IllegalArgumentException if {@code somKey} is not known
* @since 8554
*/
public static void setSystemOfMeasurement(String somKey) {
if (!SystemOfMeasurement.ALL_SYSTEMS.containsKey(somKey)) {
throw new IllegalArgumentException("Invalid system of measurement: "+somKey);
}
String oldKey = ProjectionPreference.PROP_SYSTEM_OF_MEASUREMENT.get();
if (ProjectionPreference.PROP_SYSTEM_OF_MEASUREMENT.put(somKey)) {
fireSoMChanged(oldKey, somKey);
}
}
/** First value, in meters, used to translate unit according to above formula. */
public final double aValue;
/** Second value, in meters, used to translate unit according to above formula. */
public final double bValue;
/** First unit used to format text. */
public final String aName;
/** Second unit used to format text. */
public final String bName;
/** Speed value for the most common speed symbol, in meters per second
* @since 10175 */
public final double speedValue;
/** Most common speed symbol (kmh/h, mph, kn, etc.)
* @since 10175 */
public final String speedName;
/** Specific optional area value, in squared meters, between {@code aValue*aValue} and {@code bValue*bValue}. Set to {@code -1} if not used.
* @since 5870 */
public final double areaCustomValue;
/** Specific optional area unit. Set to {@code null} if not used.
* @since 5870 */
public final String areaCustomName;
/**
* System of measurement. Currently covers only length (and area) units.
*
* If a quantity x is given in m (x_m) and in unit a (x_a) then it translates as
* x_a == x_m / aValue
*
* @param aValue First value, in meters, used to translate unit according to above formula.
* @param aName First unit used to format text.
* @param bValue Second value, in meters, used to translate unit according to above formula.
* @param bName Second unit used to format text.
* @param speedName the most common speed symbol (kmh/h, mph, kn, etc.)
* @param speedValue the speed value for the most common speed symbol, for 1 meter per second
* @since 10175
*/
public SystemOfMeasurement(double aValue, String aName, double bValue, String bName, String speedName, double speedValue) {
this(aValue, aName, bValue, bName, speedName, speedValue, -1, null);
}
/**
* System of measurement. Currently covers only length (and area) units.
*
* If a quantity x is given in m (x_m) and in unit a (x_a) then it translates as
* x_a == x_m / aValue
*
* @param aValue First value, in meters, used to translate unit according to above formula.
* @param aName First unit used to format text.
* @param bValue Second value, in meters, used to translate unit according to above formula.
* @param bName Second unit used to format text.
* @param speedName the most common speed symbol (kmh/h, mph, kn, etc.)
* @param speedValue the speed value for the most common speed symbol, for 1 meter per second
* @param areaCustomValue Specific optional area value, in squared meters, between {@code aValue*aValue} and {@code bValue*bValue}.
* Set to {@code -1} if not used.
* @param areaCustomName Specific optional area unit. Set to {@code null} if not used.
*
* @since 10175
*/
public SystemOfMeasurement(double aValue, String aName, double bValue, String bName, String speedName, double speedValue,
double areaCustomValue, String areaCustomName) {
this.aValue = aValue;
this.aName = aName;
this.bValue = bValue;
this.bName = bName;
this.speedValue = speedValue;
this.speedName = speedName;
this.areaCustomValue = areaCustomValue;
this.areaCustomName = areaCustomName;
}
/**
* Returns the text describing the given distance in this system of measurement.
* @param dist The distance in metres
* @return The text describing the given distance in this system of measurement.
*/
public String getDistText(double dist) {
return getDistText(dist, null, 0.01);
}
/**
* Returns the text describing the given distance in this system of measurement.
* @param dist The distance in metres
* @param format A {@link NumberFormat} to format the area value
* @param threshold Values lower than this {@code threshold} are displayed as {@code "< [threshold]"}
* @return The text describing the given distance in this system of measurement.
* @since 6422
*/
public String getDistText(final double dist, final NumberFormat format, final double threshold) {
double a = dist / aValue;
if (a > bValue / aValue && !Main.pref.getBoolean("system_of_measurement.use_only_lower_unit", false))
return formatText(dist / bValue, bName, format);
else if (a < threshold)
return "< " + formatText(threshold, aName, format);
else
return formatText(a, aName, format);
}
/**
* Returns the text describing the given area in this system of measurement.
* @param area The area in square metres
* @return The text describing the given area in this system of measurement.
* @since 5560
*/
public String getAreaText(double area) {
return getAreaText(area, null, 0.01);
}
/**
* Returns the text describing the given area in this system of measurement.
* @param area The area in square metres
* @param format A {@link NumberFormat} to format the area value
* @param threshold Values lower than this {@code threshold} are displayed as {@code "< [threshold]"}
* @return The text describing the given area in this system of measurement.
* @since 6422
*/
public String getAreaText(final double area, final NumberFormat format, final double threshold) {
double a = area / (aValue*aValue);
boolean lowerOnly = Main.pref.getBoolean("system_of_measurement.use_only_lower_unit", false);
boolean customAreaOnly = Main.pref.getBoolean("system_of_measurement.use_only_custom_area_unit", false);
if ((!lowerOnly && areaCustomValue > 0 && a > areaCustomValue / (aValue*aValue)
&& a < (bValue*bValue) / (aValue*aValue)) || customAreaOnly)
return formatText(area / areaCustomValue, areaCustomName, format);
else if (!lowerOnly && a >= (bValue*bValue) / (aValue*aValue))
return formatText(area / (bValue * bValue), bName + '\u00b2', format);
else if (a < threshold)
return "< " + formatText(threshold, aName + '\u00b2', format);
else
return formatText(a, aName + '\u00b2', format);
}
private static String formatText(double v, String unit, NumberFormat format) {
if (format != null) {
return format.format(v) + ' ' + unit;
}
return String.format(Locale.US, v < 9.999999 ? "%.2f %s" : "%.1f %s", v, unit);
}
}