Add area units to QgsUnitTypes (refs #13209)

Author: nyalldawson

python/core/qgsunittypes.sip

@@ -21,6 +21,20 @@ class QgsUnitTypes
       UnknownType, /*!< unknown unit type */
     };
 
+    //! Units of area
+    enum AreaUnit
+    {
+      SquareMeters, /*!< square meters */
+      SquareKilometers, /*!< square kilometers */
+      SquareFeet, /*!< square feet */
+      SquareYards, /*!< square yards */
+      SquareMiles, /*!< square miles */
+      Hectares, /*!< hectares */
+      Acres, /*!< acres */
+      SquareDegrees, /*!< square degrees, for planar geographic CRS area measurements */
+      UnknownAreaUnit, /*!< unknown areal unit */
+    };
+
     /** Returns the type for a distance unit.
      */
     static DistanceUnitType unitType( QGis::UnitType unit );
@@ -42,7 +56,7 @@ class QgsUnitTypes
 
     /** Returns a translated string representing a distance unit.
      * @param unit unit to convert to string
-     * @see fromString()
+     * @see stringToDistanceUnit()
      */
     static QString toString( QGis::UnitType unit );
 
@@ -60,6 +74,44 @@ class QgsUnitTypes
      */
     static double fromUnitToUnitFactor( QGis::UnitType fromUnit, QGis::UnitType toUnit );
 
+    /** Returns the type for an areal unit.
+    */
+    static DistanceUnitType unitType( AreaUnit unit );
+
+    /** Encodes an areal unit to a string.
+     * @param unit unit to encode
+     * @returns encoded string
+     * @see decodeAreaUnit()
+    */
+    static QString encodeUnit( AreaUnit unit );
+
+    /** Decodes an areal unit from a string.
+     * @param string string to decode
+     * @param ok optional boolean, will be set to true if string was converted successfully
+     * @returns decoded units
+     * @see encodeUnit()
+    */
+    static AreaUnit decodeAreaUnit( const QString& string, bool *ok = 0 );
+
+    /** Returns a translated string representing an areal unit.
+     * @param unit unit to convert to string
+     * @see stringToAreaUnit()
+     */
+    static QString toString( AreaUnit unit );
+
+    /** Converts a translated string to an areal unit.
+     * @param string string representing an areal unit
+     * @param ok optional boolean, will be set to true if string was converted successfully
+     * @see toString()
+     */
+    static AreaUnit stringToAreaUnit( const QString& string, bool *ok = 0 );
+
+    /** Returns the conversion factor between the specified areal units.
+     * @param fromUnit area unit to convert from
+     * @param toUnit area unit to convert to
+     * @returns multiplication factor to convert between units
+     */
+    static double fromUnitToUnitFactor( AreaUnit fromUnit, AreaUnit toUnit );
 
     /** Encodes a symbol unit to a string.
      * @param unit unit to encode

src/core/qgsunittypes.cpp

@@ -41,6 +41,29 @@ QgsUnitTypes::DistanceUnitType QgsUnitTypes::unitType( QGis::UnitType unit )
   return UnknownType;
 }
 
+QgsUnitTypes::DistanceUnitType QgsUnitTypes::unitType( QgsUnitTypes::AreaUnit unit )
+{
+  switch ( unit )
+  {
+    case SquareMeters:
+    case SquareKilometers:
+    case SquareFeet:
+    case SquareYards:
+    case SquareMiles:
+    case Hectares:
+    case Acres:
+      return Standard;
+
+    case SquareDegrees:
+      return Geographic;
+
+    case UnknownAreaUnit:
+      return UnknownType;
+  }
+
+  return UnknownType;
+}
+
 QString QgsUnitTypes::encodeUnit( QGis::UnitType unit )
 {
   switch ( unit )
@@ -203,6 +226,242 @@ double QgsUnitTypes::fromUnitToUnitFactor( QGis::UnitType fromUnit, QGis::UnitTy
   return 1.0;
 }
 
+QString QgsUnitTypes::encodeUnit( QgsUnitTypes::AreaUnit unit )
+{
+  switch ( unit )
+  {
+    case SquareMeters:
+      return "m2";
+    case SquareKilometers:
+      return "km2";
+    case SquareFeet:
+      return "ft2";
+    case SquareYards:
+      return "y2";
+    case SquareMiles:
+      return "mi2";
+    case Hectares:
+      return "ha";
+    case Acres:
+      return "ac";
+    case SquareDegrees:
+      return "deg2";
+    case UnknownAreaUnit:
+      return "<unknown>";
+  }
+  return QString();
+}
+
+QgsUnitTypes::AreaUnit QgsUnitTypes::decodeAreaUnit( const QString& string, bool* ok )
+{
+  QString normalized = string.trimmed().toLower();
+
+  if ( ok )
+    *ok = true;
+
+  if ( normalized == encodeUnit( SquareMeters ) )
+    return SquareMeters;
+  if ( normalized == encodeUnit( SquareKilometers ) )
+    return SquareKilometers;
+  if ( normalized == encodeUnit( SquareFeet ) )
+    return SquareFeet;
+  if ( normalized == encodeUnit( SquareYards ) )
+    return SquareYards;
+  if ( normalized == encodeUnit( SquareMiles ) )
+    return SquareMiles;
+  if ( normalized == encodeUnit( Hectares ) )
+    return Hectares;
+  if ( normalized == encodeUnit( Acres ) )
+    return Acres;
+  if ( normalized == encodeUnit( SquareMiles ) )
+    return SquareMiles;
+  if ( normalized == encodeUnit( SquareDegrees ) )
+    return SquareDegrees;
+  if ( normalized == encodeUnit( UnknownAreaUnit ) )
+    return UnknownAreaUnit;
+
+  if ( ok )
+    *ok = false;
+
+  return UnknownAreaUnit;
+}
+
+QString QgsUnitTypes::toString( QgsUnitTypes::AreaUnit unit )
+{
+  switch ( unit )
+  {
+    case SquareMeters:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square meters" );
+    case SquareKilometers:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square kilometers" );
+    case SquareFeet:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square feet" );
+    case SquareYards:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square yards" );
+    case SquareMiles:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square miles" );
+    case Hectares:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "hectares" );
+    case Acres:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "acres" );
+    case SquareDegrees:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "square degrees" );
+    case UnknownAreaUnit:
+      return QCoreApplication::translate( "QgsUnitTypes::AreaUnit", "<unknown>" );
+  }
+  return QString();
+}
+
+QgsUnitTypes::AreaUnit QgsUnitTypes::stringToAreaUnit( const QString& string, bool* ok )
+{
+  QString normalized = string.trimmed().toLower();
+
+  if ( ok )
+    *ok = true;
+
+  if ( normalized == toString( SquareMeters ) )
+    return SquareMeters;
+  if ( normalized == toString( SquareKilometers ) )
+    return SquareKilometers;
+  if ( normalized == toString( SquareFeet ) )
+    return SquareFeet;
+  if ( normalized == toString( SquareYards ) )
+    return SquareYards;
+  if ( normalized == toString( SquareMiles ) )
+    return SquareMiles;
+  if ( normalized == toString( Hectares ) )
+    return Hectares;
+  if ( normalized == toString( Acres ) )
+    return Acres;
+  if ( normalized == toString( SquareDegrees ) )
+    return SquareDegrees;
+  if ( normalized == toString( UnknownAreaUnit ) )
+    return UnknownAreaUnit;
+  if ( ok )
+    *ok = false;
+
+  return UnknownAreaUnit;
+}
+
+double QgsUnitTypes::fromUnitToUnitFactor( QgsUnitTypes::AreaUnit fromUnit, QgsUnitTypes::AreaUnit toUnit )
+{
+#define KM2_TO_M2 1000000.0
+#define FT2_TO_M2 0.09290304
+#define YD2_TO_M2 0.83612736
+#define MI2_TO_M2 2589988.110336
+#define HA_TO_M2 10000.0
+#define AC_TO_FT2 43560.0
+#define DEG2_TO_M2 12392029030.5
+
+  // Calculate the conversion factor between the specified units
+  if ( fromUnit != toUnit )
+  {
+    switch ( fromUnit )
+    {
+      case SquareMeters:
+      {
+        if ( toUnit == SquareKilometers ) return 1.0 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return 1.0 / FT2_TO_M2;
+        if ( toUnit == SquareYards ) return 1.0 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return 1.0 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return 1.0 / HA_TO_M2;
+        if ( toUnit == Acres ) return 1.0 / AC_TO_FT2 / FT2_TO_M2;
+        if ( toUnit == SquareDegrees ) return 1.0 / DEG2_TO_M2;
+
+        break;
+      }
+      case SquareKilometers:
+      {
+        if ( toUnit == SquareMeters ) return KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return KM2_TO_M2 / FT2_TO_M2 ;
+        if ( toUnit == SquareYards ) return KM2_TO_M2 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return KM2_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return KM2_TO_M2 / HA_TO_M2;
+        if ( toUnit == Acres ) return KM2_TO_M2 / AC_TO_FT2 / FT2_TO_M2 ;
+        if ( toUnit == SquareDegrees ) return KM2_TO_M2 / DEG2_TO_M2;
+
+        break;
+      }
+      case SquareFeet:
+      {
+        if ( toUnit == SquareMeters ) return FT2_TO_M2;
+        if ( toUnit == SquareKilometers ) return FT2_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareYards ) return FT2_TO_M2 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return FT2_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return FT2_TO_M2 / HA_TO_M2;
+        if ( toUnit == Acres ) return 1.0 / AC_TO_FT2;
+        if ( toUnit == SquareDegrees ) return FT2_TO_M2 / DEG2_TO_M2;
+
+        break;
+      }
+
+      case SquareYards:
+      {
+        if ( toUnit == SquareMeters ) return YD2_TO_M2;
+        if ( toUnit == SquareKilometers ) return YD2_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return YD2_TO_M2 / FT2_TO_M2;
+        if ( toUnit == SquareMiles ) return YD2_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return YD2_TO_M2 / HA_TO_M2;
+        if ( toUnit == Acres ) return YD2_TO_M2 / FT2_TO_M2 / AC_TO_FT2;
+        if ( toUnit == SquareDegrees ) return YD2_TO_M2 / DEG2_TO_M2;
+        break;
+      }
+
+      case SquareMiles:
+      {
+        if ( toUnit == SquareMeters ) return MI2_TO_M2;
+        if ( toUnit == SquareKilometers ) return MI2_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return MI2_TO_M2 / FT2_TO_M2;
+        if ( toUnit == SquareYards ) return MI2_TO_M2 / YD2_TO_M2;
+        if ( toUnit == Hectares ) return MI2_TO_M2 / HA_TO_M2;
+        if ( toUnit == Acres ) return MI2_TO_M2 / FT2_TO_M2 / AC_TO_FT2;
+        if ( toUnit == SquareDegrees ) return MI2_TO_M2 / DEG2_TO_M2;
+        break;
+      }
+
+      case Hectares:
+      {
+        if ( toUnit == SquareMeters ) return HA_TO_M2;
+        if ( toUnit == SquareKilometers ) return HA_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return HA_TO_M2 / FT2_TO_M2;
+        if ( toUnit == SquareYards ) return HA_TO_M2 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return HA_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Acres ) return HA_TO_M2 / FT2_TO_M2 / AC_TO_FT2;
+        if ( toUnit == SquareDegrees ) return HA_TO_M2 / DEG2_TO_M2;
+        break;
+      }
+
+      case Acres:
+      {
+        if ( toUnit == SquareMeters ) return AC_TO_FT2 * FT2_TO_M2;
+        if ( toUnit == SquareKilometers ) return AC_TO_FT2 * FT2_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return AC_TO_FT2;
+        if ( toUnit == SquareYards ) return AC_TO_FT2 * FT2_TO_M2 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return AC_TO_FT2 * FT2_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return AC_TO_FT2 * FT2_TO_M2 / HA_TO_M2;
+        if ( toUnit == SquareDegrees ) return AC_TO_FT2 * FT2_TO_M2 / DEG2_TO_M2;
+        break;
+      }
+
+      case SquareDegrees:
+      {
+        if ( toUnit == SquareMeters ) return DEG2_TO_M2;
+        if ( toUnit == SquareKilometers ) return DEG2_TO_M2 / KM2_TO_M2;
+        if ( toUnit == SquareFeet ) return DEG2_TO_M2 / FT2_TO_M2;
+        if ( toUnit == SquareYards ) return DEG2_TO_M2 / YD2_TO_M2;
+        if ( toUnit == SquareMiles ) return DEG2_TO_M2 / MI2_TO_M2;
+        if ( toUnit == Hectares ) return DEG2_TO_M2 / HA_TO_M2;
+        if ( toUnit == Acres ) return DEG2_TO_M2 / FT2_TO_M2 / AC_TO_FT2;
+        break;
+      }
+
+      case UnknownAreaUnit:
+        break;
+    }
+  }
+  return 1.0;
+}
+
 QString QgsUnitTypes::encodeUnit( QgsSymbolV2::OutputUnit unit )
 {
   switch ( unit )