Quantum GIS API Documentation  1.7.4
src/analysis/vector/qgsoverlayanalyzer.cpp
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00001 /***************************************************************************
00002     qgsoverlayanalyzer.cpp - QGIS Tools for vector geometry analysis
00003                              -------------------
00004     begin                : 8 Nov 2009
00005     copyright            : (C) Carson J. Q. Farmer
00006     email                : carson.farmer@gmail.com
00007  ***************************************************************************/
00008 
00009 /***************************************************************************
00010  *                                                                         *
00011  *   This program is free software; you can redistribute it and/or modify  *
00012  *   it under the terms of the GNU General Public License as published by  *
00013  *   the Free Software Foundation; either version 2 of the License, or     *
00014  *   (at your option) any later version.                                   *
00015  *                                                                         *
00016  ***************************************************************************/
00017 /* $Id: qgis.h 9774 2008-12-12 05:41:24Z timlinux $ */
00018 
00019 #include "qgsoverlayanalyzer.h"
00020 
00021 #include "qgsapplication.h"
00022 #include "qgsfield.h"
00023 #include "qgsfeature.h"
00024 #include "qgslogger.h"
00025 #include "qgscoordinatereferencesystem.h"
00026 #include "qgsvectorfilewriter.h"
00027 #include "qgsvectordataprovider.h"
00028 #include "qgsdistancearea.h"
00029 #include <QProgressDialog>
00030 
00031 bool QgsOverlayAnalyzer::intersection( QgsVectorLayer* layerA, QgsVectorLayer* layerB,
00032                                        const QString& shapefileName, bool onlySelectedFeatures,
00033                                        QProgressDialog* p )
00034 {
00035   if ( !layerA && !layerB )
00036   {
00037     return false;
00038   }
00039 
00040   QgsVectorDataProvider* dpA = layerA->dataProvider();
00041   QgsVectorDataProvider* dpB = layerB->dataProvider();
00042   if ( !dpA && !dpB )
00043   {
00044     return false;
00045   }
00046 
00047   QGis::WkbType outputType = dpA->geometryType();
00048   const QgsCoordinateReferenceSystem crs = layerA->crs();
00049   QgsFieldMap fieldsA = dpA->fields();
00050   QgsFieldMap fieldsB = dpB->fields();
00051   combineFieldLists( fieldsA, fieldsB );
00052 
00053   QgsVectorFileWriter vWriter( shapefileName, dpA->encoding(), fieldsA, outputType, &crs );
00054   QgsFeature currentFeature;
00055   QgsSpatialIndex index;
00056 
00057   //take only selection
00058   if ( onlySelectedFeatures )
00059   {
00060     const QgsFeatureIds selectionB = layerB->selectedFeaturesIds();
00061     QgsFeatureIds::const_iterator it = selectionB.constBegin();
00062     for ( ; it != selectionB.constEnd(); ++it )
00063     {
00064       if ( !layerB->featureAtId( *it, currentFeature, true, true ) )
00065       {
00066         continue;
00067       }
00068       index.insertFeature( currentFeature );
00069     }
00070     //use QgsVectorLayer::featureAtId
00071     const QgsFeatureIds selectionA = layerA->selectedFeaturesIds();
00072     if ( p )
00073     {
00074       p->setMaximum( selectionA.size() );
00075     }
00076     QgsFeature currentFeature;
00077     int processedFeatures = 0;
00078     it = selectionA.constBegin();
00079     for ( ; it != selectionA.constEnd(); ++it )
00080     {
00081       if ( p )
00082       {
00083         p->setValue( processedFeatures );
00084       }
00085 
00086       if ( p && p->wasCanceled() )
00087       {
00088         break;
00089       }
00090       if ( !layerA->featureAtId( *it, currentFeature, true, true ) )
00091       {
00092         continue;
00093       }
00094       intersectFeature( currentFeature, &vWriter, layerB, &index );
00095       ++processedFeatures;
00096     }
00097 
00098     if ( p )
00099     {
00100       p->setValue( selectionA.size() );
00101     }
00102   }
00103   //take all features
00104   else
00105   {
00106     layerB->select( layerB->pendingAllAttributesList(), QgsRectangle(), true, false );
00107     while ( layerB->nextFeature( currentFeature ) )
00108     {
00109       index.insertFeature( currentFeature );
00110     }
00111     QgsFeature currentFeature;
00112     layerA->select( layerA->pendingAllAttributesList(), QgsRectangle(), true, false );
00113 
00114     int featureCount = layerA->featureCount();
00115     if ( p )
00116     {
00117       p->setMaximum( featureCount );
00118     }
00119     int processedFeatures = 0;
00120 
00121     while ( layerA->nextFeature( currentFeature ) )
00122     {
00123       if ( p )
00124       {
00125         p->setValue( processedFeatures );
00126       }
00127       if ( p && p->wasCanceled() )
00128       {
00129         break;
00130       }
00131       intersectFeature( currentFeature, &vWriter, layerB, &index );
00132       ++processedFeatures;
00133     }
00134     if ( p )
00135     {
00136       p->setValue( featureCount );
00137     }
00138   }
00139   return true;
00140 }
00141 
00142 void QgsOverlayAnalyzer::intersectFeature( QgsFeature& f, QgsVectorFileWriter* vfw,
00143     QgsVectorLayer* vl, QgsSpatialIndex* index )
00144 {
00145   QgsGeometry* featureGeometry = f.geometry();
00146   QgsGeometry* intersectGeometry = 0;
00147   QgsFeature overlayFeature;
00148 
00149   if ( !featureGeometry )
00150   {
00151     return;
00152   }
00153 
00154   QList<int> intersects;
00155   intersects = index->intersects( featureGeometry->boundingBox() );
00156   QList<int>::const_iterator it = intersects.constBegin();
00157   QgsFeature outFeature;
00158   for ( ; it != intersects.constEnd(); ++it )
00159   {
00160     if ( !vl->featureAtId( *it, overlayFeature, true, true ) )
00161     {
00162       continue;
00163     }
00164 
00165     if ( featureGeometry->intersects( overlayFeature.geometry() ) )
00166     {
00167       intersectGeometry = featureGeometry->intersection( overlayFeature.geometry() );
00168 
00169       outFeature.setGeometry( intersectGeometry );
00170       QgsAttributeMap attributeMapA = f.attributeMap();
00171       QgsAttributeMap attributeMapB = overlayFeature.attributeMap();
00172       combineAttributeMaps( attributeMapA, attributeMapB );
00173       outFeature.setAttributeMap( attributeMapA );
00174 
00175       //add it to vector file writer
00176       if ( vfw )
00177       {
00178         vfw->addFeature( outFeature );
00179       }
00180     }
00181   }
00182 }
00183 
00184 void QgsOverlayAnalyzer::combineFieldLists( QgsFieldMap& fieldListA, QgsFieldMap fieldListB )
00185 {
00186   QList<QString> names;
00187   QMap<int, QgsField>::const_iterator j = fieldListA.constBegin();
00188   while ( j != fieldListA.constEnd() )
00189   {
00190     names.append( j.value().name() );
00191     ++j;
00192   }
00193   QMap<int, QgsField>::const_iterator i = fieldListB.constBegin();
00194   int count = 0;
00195   int fcount = fieldListA.size();
00196   QgsField field;
00197   while ( i != fieldListB.constEnd() )
00198   {
00199     field = i.value();
00200     while ( names.contains( field.name() ) )
00201     {
00202       QString name = field.name();
00203       name.append( "_" ).append( QString( count ) );
00204       field = QgsField( name, field.type() );
00205       ++count;
00206     }
00207     fieldListA.insert( fcount, field );
00208     count = 0;
00209     ++fcount;
00210     ++i;
00211   }
00212 }
00213 
00214 void QgsOverlayAnalyzer::combineAttributeMaps( QgsAttributeMap& attributeMapA, QgsAttributeMap attributeMapB )
00215 {
00216   QMap<int, QVariant>::const_iterator i = attributeMapB.constBegin();
00217   QVariant attribute;
00218   int fcount = attributeMapA.size();
00219   while ( i != attributeMapB.constEnd() )
00220   {
00221     attribute = i.value();
00222     attributeMapA.insert( fcount, attribute );
00223     ++i;
00224     ++fcount;
00225   }
00226 }
00227 
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