Example #1
0
QMap< QString, QString > QgsMapToolIdentify::featureDerivedAttributes( QgsFeature *feature, QgsMapLayer *layer, const QgsPoint& layerPoint )
{
  // Calculate derived attributes and insert:
  // measure distance or area depending on geometry type
  QMap< QString, QString > derivedAttributes;

  // init distance/area calculator
  QString ellipsoid = QgsProject::instance()->ellipsoid();
  QgsDistanceArea calc;
  calc.setEllipsoidalMode( mCanvas->hasCrsTransformEnabled() );
  calc.setEllipsoid( ellipsoid );
  calc.setSourceCrs( layer->crs().srsid() );

  QgsWkbTypes::Type wkbType = QgsWkbTypes::NoGeometry;
  QgsWkbTypes::GeometryType geometryType = QgsWkbTypes::NullGeometry;

  QgsVertexId vId;
  QgsPointV2 closestPoint;
  if ( feature->hasGeometry() )
  {
    geometryType = feature->geometry().type();
    wkbType = feature->geometry().geometry()->wkbType();
    //find closest vertex to clicked point
    closestPoint = QgsGeometryUtils::closestVertex( *feature->geometry().geometry(), QgsPointV2( layerPoint.x(), layerPoint.y() ), vId );
  }

  if ( QgsWkbTypes::isMultiType( wkbType ) )
  {
    QString str = QLocale::system().toString( static_cast<const QgsGeometryCollection*>( feature->geometry().geometry() )->numGeometries() );
    derivedAttributes.insert( tr( "Parts" ), str );
    str = QLocale::system().toString( vId.part + 1 );
    derivedAttributes.insert( tr( "Part number" ), str );
  }

  if ( geometryType == QgsWkbTypes::LineGeometry )
  {
    double dist = calc.measureLength( feature->geometry() );
    dist = calc.convertLengthMeasurement( dist, displayDistanceUnits() );
    QString str = formatDistance( dist );
    derivedAttributes.insert( tr( "Length" ), str );

    const QgsCurve* curve = dynamic_cast< const QgsCurve* >( feature->geometry().geometry() );
    if ( curve )
    {
      str = QLocale::system().toString( curve->nCoordinates() );
      derivedAttributes.insert( tr( "Vertices" ), str );

      //add details of closest vertex to identify point
      closestVertexAttributes( *curve, vId, layer, derivedAttributes );

      // Add the start and end points in as derived attributes
      QgsPoint pnt = mCanvas->mapSettings().layerToMapCoordinates( layer, QgsPoint( curve->startPoint().x(), curve->startPoint().y() ) );
      str = formatXCoordinate( pnt );
      derivedAttributes.insert( tr( "firstX", "attributes get sorted; translation for lastX should be lexically larger than this one" ), str );
      str = formatYCoordinate( pnt );
      derivedAttributes.insert( tr( "firstY" ), str );
      pnt = mCanvas->mapSettings().layerToMapCoordinates( layer, QgsPoint( curve->endPoint().x(), curve->endPoint().y() ) );
      str = formatXCoordinate( pnt );
      derivedAttributes.insert( tr( "lastX", "attributes get sorted; translation for firstX should be lexically smaller than this one" ), str );
      str = formatYCoordinate( pnt );
      derivedAttributes.insert( tr( "lastY" ), str );
    }
  }
  else if ( geometryType == QgsWkbTypes::PolygonGeometry )
  {
    double area = calc.measureArea( feature->geometry() );
    area = calc.convertAreaMeasurement( area, displayAreaUnits() );
    QString str = formatArea( area );
    derivedAttributes.insert( tr( "Area" ), str );

    double perimeter = calc.measurePerimeter( feature->geometry() );
    perimeter = calc.convertLengthMeasurement( perimeter, displayDistanceUnits() );
    str = formatDistance( perimeter );
    derivedAttributes.insert( tr( "Perimeter" ), str );

    str = QLocale::system().toString( feature->geometry().geometry()->nCoordinates() );
    derivedAttributes.insert( tr( "Vertices" ), str );

    //add details of closest vertex to identify point
    closestVertexAttributes( *feature->geometry().geometry(), vId, layer, derivedAttributes );
  }
  else if ( geometryType == QgsWkbTypes::PointGeometry &&
            QgsWkbTypes::flatType( wkbType ) == QgsWkbTypes::Point )
  {
    // Include the x and y coordinates of the point as a derived attribute
    QgsPoint pnt = mCanvas->mapSettings().layerToMapCoordinates( layer, feature->geometry().asPoint() );
    QString str = formatXCoordinate( pnt );
    derivedAttributes.insert( "X", str );
    str = formatYCoordinate( pnt );
    derivedAttributes.insert( "Y", str );

    if ( QgsWkbTypes::hasZ( wkbType ) )
    {
      str = QLocale::system().toString( static_cast<const QgsPointV2*>( feature->geometry().geometry() )->z(), 'g', 10 );
      derivedAttributes.insert( "Z", str );
    }
    if ( QgsWkbTypes::hasM( wkbType ) )
    {
      str = QLocale::system().toString( static_cast<const QgsPointV2*>( feature->geometry().geometry() )->m(), 'g', 10 );
      derivedAttributes.insert( "M", str );
    }
  }

  return derivedAttributes;
}
void TestQgsDistanceArea::measureAreaAndUnits()
{
  QgsDistanceArea da;
  da.setSourceCrs( 3452 );
  da.setEllipsoidalMode( false );
  da.setEllipsoid( "NONE" );
  QgsCoordinateReferenceSystem daCRS;
  daCRS.createFromSrsId( da.sourceCrsId() );
  QgsPolyline ring;
  ring << QgsPoint( 0, 0 )
  << QgsPoint( 1, 0 )
  << QgsPoint( 1, 1 )
  << QgsPoint( 2, 1 )
  << QgsPoint( 2, 2 )
  << QgsPoint( 0, 2 )
  << QgsPoint( 0, 0 );
  QgsPolygon poly;
  poly << ring;

  QgsGeometry polygon( QgsGeometry::fromPolygon( poly ) );

  // We check both the measured area AND the units, in case the logic regarding
  // ellipsoids and units changes in future
  double area = da.measureArea( &polygon );
  QgsUnitTypes::AreaUnit units = da.areaUnits();

  QgsDebugMsg( QString( "measured %1 in %2" ).arg( area ).arg( QgsUnitTypes::toString( units ) ) );

  QVERIFY(( qgsDoubleNear( area, 3.0, 0.00000001 ) && units == QgsUnitTypes::AreaSquareDegrees )
          || ( qgsDoubleNear( area, 37176087091.5, 0.1 ) && units == QgsUnitTypes::AreaSquareMeters ) );

  da.setEllipsoid( "WGS84" );
  area = da.measureArea( &polygon );
  units = da.areaUnits();

  QgsDebugMsg( QString( "measured %1 in %2" ).arg( area ).arg( QgsUnitTypes::toString( units ) ) );
  QVERIFY(( qgsDoubleNear( area, 3.0, 0.00000001 ) && units == QgsUnitTypes::AreaSquareDegrees )
          || ( qgsDoubleNear( area, 37176087091.5, 0.1 ) && units == QgsUnitTypes::AreaSquareMeters ) );

  da.setEllipsoidalMode( true );
  area = da.measureArea( &polygon );
  units = da.areaUnits();

  QgsDebugMsg( QString( "measured %1 in %2" ).arg( area ).arg( QgsUnitTypes::toString( units ) ) );
  // should always be in Meters Squared
  QGSCOMPARENEAR( area, 37416879192.9, 0.1 );
  QCOMPARE( units, QgsUnitTypes::AreaSquareMeters );

  // test converting the resultant area
  area = da.convertAreaMeasurement( area, QgsUnitTypes::AreaSquareMiles );
  QGSCOMPARENEAR( area, 14446.7378, 0.001 );

  // now try with a source CRS which is in feet
  ring.clear();
  ring << QgsPoint( 1850000, 4423000 )
  << QgsPoint( 1851000, 4423000 )
  << QgsPoint( 1851000, 4424000 )
  << QgsPoint( 1852000, 4424000 )
  << QgsPoint( 1852000, 4425000 )
  << QgsPoint( 1851000, 4425000 )
  << QgsPoint( 1850000, 4423000 );
  poly.clear();
  poly << ring;
  polygon = QgsGeometry::fromPolygon( poly );

  da.setSourceCrs( 27469 );
  da.setEllipsoidalMode( false );
  // measurement should be in square feet
  area = da.measureArea( &polygon );
  units = da.areaUnits();
  QgsDebugMsg( QString( "measured %1 in %2" ).arg( area ).arg( QgsUnitTypes::toString( units ) ) );
  QGSCOMPARENEAR( area, 2000000, 0.001 );
  QCOMPARE( units, QgsUnitTypes::AreaSquareFeet );

  // test converting the resultant area
  area = da.convertAreaMeasurement( area, QgsUnitTypes::AreaSquareYards );
  QGSCOMPARENEAR( area, 222222.2222, 0.001 );

  da.setEllipsoidalMode( true );
  // now should be in Square Meters again
  area = da.measureArea( &polygon );
  units = da.areaUnits();
  QgsDebugMsg( QString( "measured %1 in %2" ).arg( area ).arg( QgsUnitTypes::toString( units ) ) );
  QGSCOMPARENEAR( area, 184149.37, 1.0 );
  QCOMPARE( units, QgsUnitTypes::AreaSquareMeters );

  // test converting the resultant area
  area = da.convertAreaMeasurement( area, QgsUnitTypes::AreaSquareYards );
  QgsDebugMsg( QString( "measured %1 in sq yrds" ).arg( area ) );
  QGSCOMPARENEAR( area, 220240.8172549, 0.00001 );
}