Skip to content
Permalink
Browse files

New class QgsOgrUtils w/helper functions for working with OGR features

Also includes handy function for converting a string to a QgsFeatureList
or QgsFields by using OGR to parse the string. This allows eg conversion
of GeoJSON to QgsFeatures.
  • Loading branch information
nyalldawson committed Mar 1, 2016
1 parent 3f80649 commit 3f62cd46e792c224b678d1736e65e5c7f5398067
@@ -154,6 +154,7 @@ SET(QGIS_CORE_SRCS
qgsobjectcustomproperties.cpp
qgsofflineediting.cpp
qgsogcutils.cpp
qgsogrutils.cpp
qgsowsconnection.cpp
qgspaintenginehack.cpp
qgspallabeling.cpp
@@ -0,0 +1,315 @@
/***************************************************************************
qgsogrutils.cpp
---------------
begin : February 2016
copyright : (C) 2016 Nyall Dawson
email : nyall dot dawson at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/

#include "qgsogrutils.h"
#include "qgsapplication.h"
#include "qgslogger.h"
#include "qgsgeometry.h"
#include <QTextCodec>
#include <QUuid>

#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 1800
#define TO8(x) (x).toUtf8().constData()
#define TO8F(x) (x).toUtf8().constData()
#define FROM8(x) QString::fromUtf8(x)
#else
#define TO8(x) (x).toLocal8Bit().constData()
#define TO8F(x) QFile::encodeName( x ).constData()
#define FROM8(x) QString::fromLocal8Bit(x)
#endif

QgsFeature QgsOgrUtils::readOgrFeature( OGRFeatureH ogrFet, const QgsFields& fields, QTextCodec* encoding )
{
QgsFeature feature;
if ( !ogrFet )
{
feature.setValid( false );
return feature;
}

feature.setFeatureId( OGR_F_GetFID( ogrFet ) );
feature.setValid( true );

if ( !readOgrFeatureGeometry( ogrFet, feature ) )
{
feature.setValid( false );
}

if ( !readOgrFeatureAttributes( ogrFet, fields, feature, encoding ) )
{
feature.setValid( false );
}

return feature;
}

QgsFields QgsOgrUtils::readOgrFields( OGRFeatureH ogrFet, QTextCodec* encoding )
{
QgsFields fields;

if ( !ogrFet )
return fields;

int fieldCount = OGR_F_GetFieldCount( ogrFet );
for ( int i = 0; i < fieldCount; ++i )
{
OGRFieldDefnH fldDef = OGR_F_GetFieldDefnRef( ogrFet, i );
if ( !fldDef )
{
fields.append( QgsField() );
continue;
}

QString name = encoding->toUnicode( OGR_Fld_GetNameRef( fldDef ) );
QVariant::Type varType;
switch ( OGR_Fld_GetType( fldDef ) )
{
case OFTInteger:
varType = QVariant::Int;
break;
#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 2000000
case OFTInteger64:
varType = QVariant::LongLong;
break;
#endif
case OFTReal:
varType = QVariant::Double;
break;
#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 1400
case OFTDate:
varType = QVariant::Date;
break;
case OFTTime:
varType = QVariant::Time;
break;
case OFTDateTime:
varType = QVariant::DateTime;
break;
case OFTString:
#endif
default:
varType = QVariant::String; // other unsupported, leave it as a string
}
fields.append( QgsField( name, varType ) );
}
return fields;
}

QVariant QgsOgrUtils::getOgrFeatureAttribute( OGRFeatureH ogrFet, const QgsFields& fields, int attIndex, QTextCodec* encoding , bool* ok )
{
if ( !ogrFet || attIndex < 0 || attIndex >= fields.count() )
{
if ( ok )
*ok = false;
return QVariant();
}

OGRFieldDefnH fldDef = OGR_F_GetFieldDefnRef( ogrFet, attIndex );

if ( ! fldDef )
{
if ( ok )
*ok = false;

QgsDebugMsg( "ogrFet->GetFieldDefnRef(attindex) returns NULL" );
return QVariant();
}

QVariant value;

if ( ok )
*ok = true;

if ( OGR_F_IsFieldSet( ogrFet, attIndex ) )
{
switch ( fields.at( attIndex ).type() )
{
case QVariant::String:
value = QVariant( encoding->toUnicode( OGR_F_GetFieldAsString( ogrFet, attIndex ) ) );
break;
case QVariant::Int:
value = QVariant( OGR_F_GetFieldAsInteger( ogrFet, attIndex ) );
break;
#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 2000000
case QVariant::LongLong:
value = QVariant( OGR_F_GetFieldAsInteger64( ogrFet, attIndex ) );
break;
#endif
case QVariant::Double:
value = QVariant( OGR_F_GetFieldAsDouble( ogrFet, attIndex ) );
break;
case QVariant::Date:
case QVariant::DateTime:
case QVariant::Time:
{
int year, month, day, hour, minute, second, tzf;

OGR_F_GetFieldAsDateTime( ogrFet, attIndex, &year, &month, &day, &hour, &minute, &second, &tzf );
if ( fields.at( attIndex ).type() == QVariant::Date )
value = QDate( year, month, day );
else if ( fields.at( attIndex ).type() == QVariant::Time )
value = QTime( hour, minute, second );
else
value = QDateTime( QDate( year, month, day ), QTime( hour, minute, second ) );
}
break;
default:
Q_ASSERT_X( false, "QgsOgrUtils::getOgrFeatureAttribute", "unsupported field type" );
if ( ok )
*ok = false;
}
}
else
{
value = QVariant( QString::null );
}

return value;
}

bool QgsOgrUtils::readOgrFeatureAttributes( OGRFeatureH ogrFet, const QgsFields& fields, QgsFeature& feature, QTextCodec* encoding )
{
// read all attributes
feature.initAttributes( fields.count() );
feature.setFields( fields );

if ( !ogrFet )
return false;

bool ok = false;
for ( int idx = 0; idx < fields.count(); ++idx )
{
QVariant value = getOgrFeatureAttribute( ogrFet, fields, idx, encoding, &ok );
if ( ok )
{
feature.setAttribute( idx, value );
}
}
return true;
}

bool QgsOgrUtils::readOgrFeatureGeometry( OGRFeatureH ogrFet, QgsFeature& feature )
{
if ( !ogrFet )
return false;

OGRGeometryH geom = OGR_F_GetGeometryRef( ogrFet );
if ( !geom )
feature.setGeometry( nullptr );
else
feature.setGeometry( ogrGeometryToQgsGeometry( geom ) );

return true;
}

QgsGeometry* QgsOgrUtils::ogrGeometryToQgsGeometry( OGRGeometryH geom )
{
if ( !geom )
return nullptr;

// get the wkb representation
int memorySize = OGR_G_WkbSize( geom );
unsigned char *wkb = new unsigned char[memorySize];
OGR_G_ExportToWkb( geom, ( OGRwkbByteOrder ) QgsApplication::endian(), wkb );

QgsGeometry *g = new QgsGeometry();
g->fromWkb( wkb, memorySize );
return g;
}

QgsFeatureList QgsOgrUtils::stringToFeatureList( const QString& string, const QgsFields& fields, QTextCodec* encoding )
{
QgsFeatureList features;
if ( string.isEmpty() )
return features;

QString randomFileName = QString( "/vsimem/%1" ).arg( QUuid::createUuid() );

// create memory file system object from string buffer
QByteArray ba = string.toUtf8();
VSIFCloseL( VSIFileFromMemBuffer( TO8( randomFileName ), reinterpret_cast< GByte* >( ba.data() ),
static_cast< vsi_l_offset >( ba.size() ), FALSE ) );

OGRDataSourceH hDS = OGROpen( TO8( randomFileName ), false, nullptr );
if ( !hDS )
{
VSIUnlink( TO8( randomFileName ) );
return features;
}

OGRLayerH ogrLayer = OGR_DS_GetLayer( hDS, 0 );
if ( !ogrLayer )
{
OGR_DS_Destroy( hDS );
VSIUnlink( TO8( randomFileName ) );
return features;
}

OGRFeatureH oFeat;
while (( oFeat = OGR_L_GetNextFeature( ogrLayer ) ) )
{
QgsFeature feat = readOgrFeature( oFeat, fields, encoding );
if ( feat.isValid() )
features << feat;

OGR_F_Destroy( oFeat );
}

OGR_DS_Destroy( hDS );
VSIUnlink( "/vsimem/clipboard.dat" );

return features;
}

QgsFields QgsOgrUtils::stringToFields( const QString& string, QTextCodec* encoding )
{
QgsFields fields;
if ( string.isEmpty() )
return fields;

QString randomFileName = QString( "/vsimem/%1" ).arg( QUuid::createUuid() );

// create memory file system object from buffer
QByteArray ba = string.toUtf8();
VSIFCloseL( VSIFileFromMemBuffer( TO8( randomFileName ), reinterpret_cast< GByte* >( ba.data() ),
static_cast< vsi_l_offset >( ba.size() ), FALSE ) );

OGRDataSourceH hDS = OGROpen( TO8( randomFileName ), false, nullptr );
if ( !hDS )
{
VSIUnlink( TO8( randomFileName ) );
return fields;
}

OGRLayerH ogrLayer = OGR_DS_GetLayer( hDS, 0 );
if ( !ogrLayer )
{
OGR_DS_Destroy( hDS );
VSIUnlink( TO8( randomFileName ) );
return fields;
}

OGRFeatureH oFeat;
//read in the first feature only
if (( oFeat = OGR_L_GetNextFeature( ogrLayer ) ) )
{
fields = readOgrFields( oFeat, encoding );
OGR_F_Destroy( oFeat );
}

OGR_DS_Destroy( hDS );
VSIUnlink( TO8( randomFileName ) );
return fields;
}

0 comments on commit 3f62cd4

Please sign in to comment.
You can’t perform that action at this time.