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[WFS Provider] Implement workarounds to better behave when extent rep…
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…orted by capabilities is wrong

Some servers like http://geodata.nationaalgeoregister.nl/bag/wfs report wrong layer
extent in their GetCapabilities response.

This commit implements a work around :
- in the 'Request only features intersecting extent' mode, if no feature is returned
  in a BBOX enclosing the GetCapabilities extent, then query a single feature to
  initialize the extent. The user will then to zoom again on layer and zoom out.
- in the other mode, the extent is updated with the feature geometry extent as soon
  as features come from the server, and the user can zoom on layer regularly to se
  it updated.
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@rouault
rouault committed May 29, 2016
1 parent 3d95712 commit 2ac20c6
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Showing 6 changed files with 333 additions and 41 deletions.
33 changes: 1 addition & 32 deletions src/providers/wfs/qgswfsfeatureiterator.cpp
View file
Expand Up @@ -389,12 +389,6 @@ void QgsWFSFeatureDownloader::run( bool serializeFeatures, int maxFeatures )
connect( &mFeatureHitsAsyncRequest, SIGNAL( downloadFinished() ), &loop, SLOT( quit() ) );
}

QgsGmlStreamingParser::AxisOrientationLogic axisOrientationLogic( QgsGmlStreamingParser::Honour_EPSG_if_urn );
if ( mShared->mURI.ignoreAxisOrientation() )
{
axisOrientationLogic = QgsGmlStreamingParser::Ignore_EPSG;
}

bool interrupted = false;
bool truncatedResponse = false;
QSettings s;
Expand All @@ -404,32 +398,7 @@ void QgsWFSFeatureDownloader::run( bool serializeFeatures, int maxFeatures )
while ( true )
{
success = true;
QgsGmlStreamingParser* parser;
if ( mShared->mLayerPropertiesList.size() )
{
QList< QgsGmlStreamingParser::LayerProperties > layerPropertiesList;
Q_FOREACH ( QgsOgcUtils::LayerProperties layerProperties, mShared->mLayerPropertiesList )
{
QgsGmlStreamingParser::LayerProperties layerPropertiesOut;
layerPropertiesOut.mName = layerProperties.mName;
layerPropertiesOut.mGeometryAttribute = layerProperties.mGeometryAttribute;
layerPropertiesList << layerPropertiesOut;
}

parser = new QgsGmlStreamingParser( layerPropertiesList,
mShared->mFields,
mShared->mMapFieldNameToSrcLayerNameFieldName,
axisOrientationLogic,
mShared->mURI.invertAxisOrientation() );
}
else
{
parser = new QgsGmlStreamingParser( mShared->mURI.typeName(),
mShared->mGeometryAttribute,
mShared->mFields,
axisOrientationLogic,
mShared->mURI.invertAxisOrientation() );
}
QgsGmlStreamingParser* parser = mShared->createParser();

QUrl url( buildURL( mTotalDownloadedFeatureCount,
maxFeatures ? maxFeatures : mShared->mMaxFeatures, false ) );
Expand Down
29 changes: 26 additions & 3 deletions src/providers/wfs/qgswfsprovider.cpp
View file
Expand Up @@ -59,6 +59,7 @@ QgsWFSProvider::QgsWFSProvider( const QString& uri, const QgsWFSCapabilities::Ca
{
mShared->mCaps = caps;
connect( mShared.data(), SIGNAL( raiseError( const QString& ) ), this, SLOT( pushErrorSlot( const QString& ) ) );
connect( mShared.data(), SIGNAL( extentUpdated() ), this, SIGNAL( fullExtentCalculated() ) );

if ( uri.isEmpty() )
{
Expand Down Expand Up @@ -684,7 +685,29 @@ QgsCoordinateReferenceSystem QgsWFSProvider::crs()

QgsRectangle QgsWFSProvider::extent()
{
return mExtent;
// Some servers return completely buggy extent in their capabilities response
// so mix it with the extent actually got from the downloaded features
QgsRectangle computedExtent( mShared->computedExtent() );
QgsDebugMsg( "computedExtent: " + computedExtent.toString() );
QgsDebugMsg( "mCapabilityExtent: " + mShared->mCapabilityExtent.toString() );

// If we didn't get any feature, then return capabilities extent.
if ( computedExtent.isNull() )
return mShared->mCapabilityExtent;

// If the capabilities extent is completely off from the features, then
// use feature extent.
// Case of standplaats layer of http://geodata.nationaalgeoregister.nl/bag/wfs
if ( !computedExtent.intersects( mShared->mCapabilityExtent ) )
return computedExtent;

if ( mShared->downloadFinished() )
{
return computedExtent;
}

computedExtent.combineExtentWith( &mShared->mCapabilityExtent );
return computedExtent;
}

bool QgsWFSProvider::isValid()
Expand Down Expand Up @@ -1378,9 +1401,9 @@ bool QgsWFSProvider::getCapabilities()
QgsDebugMsg( "src:" + src.authid() );
QgsDebugMsg( "dst:" + mShared->mSourceCRS.authid() );

mExtent = ct.transformBoundingBox( r, QgsCoordinateTransform::ForwardTransform );
mShared->mCapabilityExtent = ct.transformBoundingBox( r, QgsCoordinateTransform::ForwardTransform );

QgsDebugMsg( "layer ext:" + mExtent.toString() );
QgsDebugMsg( "layer ext:" + mShared->mCapabilityExtent.toString() );
}
if ( mShared->mCaps.featureTypes[i].insertCap )
{
Expand Down
2 changes: 0 additions & 2 deletions src/providers/wfs/qgswfsprovider.h
View file
Expand Up @@ -153,8 +153,6 @@ class QgsWFSProvider : public QgsVectorDataProvider
//! String used to define a subset of the layer
QString mSubsetString;

/** Bounding box for the layer*/
QgsRectangle mExtent;
/** Geometry type of the features in this layer*/
mutable QGis::WkbType mWKBType;
/** Flag if provider is valid*/
Expand Down
160 changes: 158 additions & 2 deletions src/providers/wfs/qgswfsshareddata.cpp
View file
Expand Up @@ -13,6 +13,8 @@
* *
***************************************************************************/

#include <math.h> // M_PI

#include "qgswfsconstants.h"
#include "qgswfsshareddata.h"
#include "qgswfsutils.h"
Expand All @@ -34,6 +36,7 @@

#include <QCryptographicHash>


QgsWFSSharedData::QgsWFSSharedData( const QString& uri )
: mURI( uri )
, mSourceCRS( 0 )
Expand All @@ -48,6 +51,7 @@ QgsWFSSharedData::QgsWFSSharedData( const QString& uri )
, mFeatureCountExact( false )
, mGetFeatureHitsIssued( false )
, mTotalFeaturesAttemptedToBeCached( 0 )
, mTryFetchingOneFeature( false )
{
// Needed because used by a signal
qRegisterMetaType< QVector<QgsWFSFeatureGmlIdPair> >( "QVector<QgsWFSFeatureGmlIdPair>" );
Expand Down Expand Up @@ -514,6 +518,7 @@ int QgsWFSSharedData::registerToCache( QgsWFSFeatureIterator* iterator, QgsRecta
delete mDownloader;
mMutex.lock();
mDownloadFinished = false;
mComputedExtent = QgsRectangle();
mDownloader = new QgsWFSThreadedFeatureDownloader( this );
QEventLoop loop;
connect( mDownloader, SIGNAL( ready() ), &loop, SLOT( quit() ) );
Expand Down Expand Up @@ -826,6 +831,7 @@ void QgsWFSSharedData::serializeFeatures( QVector<QgsWFSFeatureGmlIdPair>& featu
existingGmlIds = getExistingCachedGmlIds( featureList );
QVector<QgsWFSFeatureGmlIdPair> updatedFeatureList;

QgsRectangle localComputedExtent( mComputedExtent );
Q_FOREACH ( QgsWFSFeatureGmlIdPair featPair, featureList )
{
const QgsFeature& gmlFeature = featPair.first;
Expand Down Expand Up @@ -874,8 +880,13 @@ void QgsWFSSharedData::serializeFeatures( QVector<QgsWFSFeatureGmlIdPair>& featu

cachedFeature.setAttribute( hexwkbGeomIdx, QVariant( QString( array.toHex().data() ) ) );

QgsGeometry* polyBoudingBox = QgsGeometry::fromRect( geometry->boundingBox() );
cachedFeature.setGeometry( polyBoudingBox );
QgsRectangle bBox( geometry->boundingBox() );
if ( localComputedExtent.isNull() )
localComputedExtent = bBox;
else
localComputedExtent.combineExtentWith( &bBox );
QgsGeometry* polyBoundingBox = QgsGeometry::fromRect( bBox );
cachedFeature.setGeometry( polyBoundingBox );
}
else
{
Expand Down Expand Up @@ -936,15 +947,30 @@ void QgsWFSSharedData::serializeFeatures( QVector<QgsWFSFeatureGmlIdPair>& featu
if ( !mFeatureCountExact )
mFeatureCount += featureListToCache.size();
mTotalFeaturesAttemptedToBeCached += featureListToCache.size();
if ( !localComputedExtent.isNull() && mComputedExtent.isNull() && !mTryFetchingOneFeature &&
!localComputedExtent.intersects( mCapabilityExtent ) )
{
QgsMessageLog::logMessage( tr( "Layer extent reported by the server is not correct. "
"You may need to zoom again on layer while features are being downloaded" ), tr( "WFS" ) );
}
mComputedExtent = localComputedExtent;
}
}

featureList = updatedFeatureList;

emit extentUpdated();

QgsDebugMsg( QString( "end %1" ).arg( featureList.size() ) );

}

QgsRectangle QgsWFSSharedData::computedExtent()
{
QMutexLocker locker( &mMutex );
return mComputedExtent;
}

void QgsWFSSharedData::pushError( const QString& errorMsg )
{
QgsMessageLog::logMessage( errorMsg, tr( "WFS" ) );
Expand All @@ -970,6 +996,36 @@ void QgsWFSSharedData::endOfDownload( bool success, int featureCount,
mDownloadFinished = true;
if ( success && !mRect.isEmpty() )
{
// In the case we requested an extent that includes the extent reported by GetCapabilities response,
// that we have no filter and we got no features, then it is not unlikely that the capabilities
// might be wrong. In which case, query one feature so that we got a beginning of extent from
// which the user will be able to zoom out. This is far from being ideal...
if ( featureCount == 0 && mRect.contains( mCapabilityExtent ) && mWFSFilter.isEmpty() &&
mCaps.supportsHits && !mGeometryAttribute.isEmpty() && !mTryFetchingOneFeature )
{
QgsDebugMsg( "Capability extent is probably wrong. Starting a new request with one feature limit to get at least one feature" );
mTryFetchingOneFeature = true;
QgsWFSSingleFeatureRequest request( this );
mComputedExtent = request.getExtent();
if ( !mComputedExtent.isNull() )
{
// Grow the extent by ~ 50 km (completely arbitrary number if you wonder!)
// so that it is sufficiently zoomed out
if ( mSourceCRS.mapUnits() == QGis::Meters )
mComputedExtent.grow( 50. * 1000. );
else if ( mSourceCRS.mapUnits() == QGis::Degrees )
mComputedExtent.grow( 50. / 110 );
QgsMessageLog::logMessage( tr( "Layer extent reported by the server is not correct. You may need to zoom on layer and then zoom out to see all fetchures" ), tr( "WFS" ) );
}
mMutex.unlock();
if ( !mComputedExtent.isNull() )
{
emit extentUpdated();
}
mMutex.lock();
return;
}

// Arbitrary threshold to avoid the cache of BBOX to grow out of control.
// Note: we could be smarter and keep some BBOXes, but the saturation is
// unlikely to happen in practice, so just clear everything.
Expand Down Expand Up @@ -1099,6 +1155,41 @@ int QgsWFSSharedData::getFeatureCount( bool issueRequestIfNeeded )
return mFeatureCount;
}

QgsGmlStreamingParser* QgsWFSSharedData::createParser()
{
QgsGmlStreamingParser::AxisOrientationLogic axisOrientationLogic( QgsGmlStreamingParser::Honour_EPSG_if_urn );
if ( mURI.ignoreAxisOrientation() )
{
axisOrientationLogic = QgsGmlStreamingParser::Ignore_EPSG;
}

if ( mLayerPropertiesList.size() )
{
QList< QgsGmlStreamingParser::LayerProperties > layerPropertiesList;
Q_FOREACH ( QgsOgcUtils::LayerProperties layerProperties, mLayerPropertiesList )
{
QgsGmlStreamingParser::LayerProperties layerPropertiesOut;
layerPropertiesOut.mName = layerProperties.mName;
layerPropertiesOut.mGeometryAttribute = layerProperties.mGeometryAttribute;
layerPropertiesList << layerPropertiesOut;
}

return new QgsGmlStreamingParser( layerPropertiesList,
mFields,
mMapFieldNameToSrcLayerNameFieldName,
axisOrientationLogic,
mURI.invertAxisOrientation() );
}
else
{
return new QgsGmlStreamingParser( mURI.typeName(),
mGeometryAttribute,
mFields,
axisOrientationLogic,
mURI.invertAxisOrientation() );
}
}


// -------------------------

Expand Down Expand Up @@ -1165,3 +1256,68 @@ QString QgsWFSFeatureHitsRequest::errorMessageWithReason( const QString& reason
return tr( "Download of feature count failed: %1" ).arg( reason );
}


// -------------------------


QgsWFSSingleFeatureRequest::QgsWFSSingleFeatureRequest( QgsWFSSharedData* shared )
: QgsWFSRequest( shared->mURI.uri() ), mShared( shared )
{
}

QgsWFSSingleFeatureRequest::~QgsWFSSingleFeatureRequest()
{
}

QgsRectangle QgsWFSSingleFeatureRequest::getExtent()
{
QUrl getFeatureUrl( mUri.baseURL() );
getFeatureUrl.addQueryItem( "REQUEST", "GetFeature" );
getFeatureUrl.addQueryItem( "VERSION", mShared->mWFSVersion );
if ( mShared->mWFSVersion .startsWith( "2.0" ) )
getFeatureUrl.addQueryItem( "TYPENAMES", mUri.typeName() );
else
getFeatureUrl.addQueryItem( "TYPENAME", mUri.typeName() );
if ( mShared->mWFSVersion .startsWith( "2.0" ) )
getFeatureUrl.addQueryItem( "COUNT", QString::number( 1 ) );
else
getFeatureUrl.addQueryItem( "MAXFEATURES", QString::number( 1 ) );

if ( !sendGET( getFeatureUrl, true ) )
return -1;

const QByteArray& buffer = response();

QgsDebugMsg( "parsing QgsWFSSingleFeatureRequest: " + buffer );

// parse XML
QgsGmlStreamingParser* parser = mShared->createParser();
QString gmlProcessErrorMsg;
QgsRectangle extent;
if ( parser->processData( buffer, true, gmlProcessErrorMsg ) )
{
QVector<QgsGmlStreamingParser::QgsGmlFeaturePtrGmlIdPair> featurePtrList =
parser->getAndStealReadyFeatures();
QVector<QgsWFSFeatureGmlIdPair> featureList;
for ( int i = 0;i < featurePtrList.size();i++ )
{
QgsGmlStreamingParser::QgsGmlFeaturePtrGmlIdPair& featPair = featurePtrList[i];
QgsFeature f( *( featPair.first ) );
const QgsGeometry* geometry = f.constGeometry();
if ( geometry )
{
extent = geometry->boundingBox();
}
delete featPair.first;
}
}
delete parser;
return extent;
}

QString QgsWFSSingleFeatureRequest::errorMessageWithReason( const QString& reason )
{
return tr( "Download of feature failed: %1" ).arg( reason );
}


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