int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
{
if ( !mPolygonLayer || mPolygonLayer->geometryType() != QGis::Polygon )
{
return 1;
}
QgsVectorDataProvider* vectorProvider = mPolygonLayer->dataProvider();
if ( !vectorProvider )
{
return 2;
}
//open the raster layer and the raster band
GDALAllRegister();
GDALDatasetH inputDataset = GDALOpen( mRasterFilePath.toLocal8Bit().data(), GA_ReadOnly );
if ( inputDataset == NULL )
{
return 3;
}
if ( GDALGetRasterCount( inputDataset ) < ( mRasterBand - 1 ) )
{
GDALClose( inputDataset );
return 4;
}
GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, mRasterBand );
if ( rasterBand == NULL )
{
GDALClose( inputDataset );
return 5;
}
mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );
//get geometry info about raster layer
int nCellsX = GDALGetRasterXSize( inputDataset );
int nCellsY = GDALGetRasterYSize( inputDataset );
double geoTransform[6];
if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
{
GDALClose( inputDataset );
return 6;
}
double cellsizeX = geoTransform[1];
if ( cellsizeX < 0 )
{
cellsizeX = -cellsizeX;
}
double cellsizeY = geoTransform[5];
if ( cellsizeY < 0 )
{
cellsizeY = -cellsizeY;
}
QgsRectangle rasterBBox( geoTransform[0], geoTransform[3] - ( nCellsY * cellsizeY ), geoTransform[0] + ( nCellsX * cellsizeX ), geoTransform[3] );
//add the new count, sum, mean fields to the provider
QList<QgsField> newFieldList;
QgsField countField( mAttributePrefix + "count", QVariant::Double );
QgsField sumField( mAttributePrefix + "sum", QVariant::Double );
QgsField meanField( mAttributePrefix + "mean", QVariant::Double );
newFieldList.push_back( countField );
newFieldList.push_back( sumField );
newFieldList.push_back( meanField );
if ( !vectorProvider->addAttributes( newFieldList ) )
{
return 7;
}
//index of the new fields
int countIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "count" );
int sumIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "sum" );
int meanIndex = vectorProvider->fieldNameIndex( mAttributePrefix + "mean" );
if ( countIndex == -1 || sumIndex == -1 || meanIndex == -1 )
{
return 8;
}
//progress dialog
long featureCount = vectorProvider->featureCount();
if ( p )
{
p->setMaximum( featureCount );
}
//iterate over each polygon
vectorProvider->select( QgsAttributeList(), QgsRectangle(), true, false );
vectorProvider->rewind();
QgsFeature f;
double count = 0;
double sum = 0;
double mean = 0;
int featureCounter = 0;
while ( vectorProvider->nextFeature( f ) )
{
qWarning( "%d", featureCounter );
if ( p )
{
p->setValue( featureCounter );
}
if ( p && p->wasCanceled() )
{
break;
}
QgsGeometry* featureGeometry = f.geometry();
if ( !featureGeometry )
{
++featureCounter;
continue;
}
int offsetX, offsetY, nCellsX, nCellsY;
if ( cellInfoForBBox( rasterBBox, featureGeometry->boundingBox(), cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY ) != 0 )
{
++featureCounter;
continue;
}
statisticsFromMiddlePointTest_improved( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
rasterBBox, sum, count );
if ( count <= 1 )
{
//the cell resolution is probably larger than the polygon area. We switch to precise pixel - polygon intersection in this case
statisticsFromPreciseIntersection( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
rasterBBox, sum, count );
}
if ( count == 0 )
{
mean = 0;
}
else
{
mean = sum / count;
}
//write the statistics value to the vector data provider
QgsChangedAttributesMap changeMap;
QgsAttributeMap changeAttributeMap;
changeAttributeMap.insert( countIndex, QVariant( count ) );
changeAttributeMap.insert( sumIndex, QVariant( sum ) );
changeAttributeMap.insert( meanIndex, QVariant( mean ) );
changeMap.insert( f.id(), changeAttributeMap );
vectorProvider->changeAttributeValues( changeMap );
++featureCounter;
}
if ( p )
{
p->setValue( featureCount );
}
GDALClose( inputDataset );
return 0;
}
