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[labeling] Fix crash when labeling features and showing unplaced

labels and some labels have no candidate positions

Fixes #38093
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nyalldawson committed Sep 2, 2020
1 parent ac79bfa commit 3afe74b8c2f68de0a0fef8debf9d9fbe338fd435
@@ -656,27 +656,32 @@ void Problem::chain_search()

QList<LabelPosition *> Problem::getSolution( bool returnInactive, QList<LabelPosition *> *unlabeled )
{
QList<LabelPosition *> solList;
QList<LabelPosition *> finalLabelPlacements;

// loop through all features to be labeled
for ( std::size_t i = 0; i < mFeatureCount; i++ )
{
if ( mSol.activeLabelIds[i] != -1 )
const int labelId = mSol.activeLabelIds[i];
const bool foundNonOverlappingPlacement = labelId != -1;
const int startIndexForLabelPlacements = mFeatStartId[i];
const bool foundCandidatesForFeature = startIndexForLabelPlacements < static_cast< int >( mLabelPositions.size() );

if ( foundNonOverlappingPlacement )
{
solList.push_back( mLabelPositions[ mSol.activeLabelIds[i] ].get() ); // active labels
finalLabelPlacements.push_back( mLabelPositions[ labelId ].get() ); // active labels
}
else if ( returnInactive
|| ( mFeatStartId[i] < static_cast< int >( mLabelPositions.size() ) &&
( mLabelPositions.at( mFeatStartId[i] )->getFeaturePart()->layer()->displayAll()
|| mLabelPositions.at( mFeatStartId[i] )->getFeaturePart()->alwaysShow() ) ) )
else if ( foundCandidatesForFeature &&
( returnInactive // allowing any overlapping labels regardless of where they are from
|| mLabelPositions.at( startIndexForLabelPlacements )->getFeaturePart()->layer()->displayAll() // allowing overlapping labels for the layer
|| mLabelPositions.at( startIndexForLabelPlacements )->getFeaturePart()->alwaysShow() ) ) // allowing overlapping labels for the feature
{
solList.push_back( mLabelPositions[ mFeatStartId[i] ].get() ); // unplaced label
finalLabelPlacements.push_back( mLabelPositions[ startIndexForLabelPlacements ].get() ); // unplaced label
}
else if ( unlabeled )
{
const int startPos = mFeatStartId[i];
// need to be careful here -- if the next feature's start id is the same as this one, then this feature had no candidates!
if ( startPos < static_cast< int >( mLabelPositions.size() ) && ( i == mFeatureCount - 1 || startPos != mFeatStartId[i + 1] ) )
unlabeled->push_back( mLabelPositions[ startPos ].get() );
if ( foundCandidatesForFeature && ( i == mFeatureCount - 1 || startIndexForLabelPlacements != mFeatStartId[i + 1] ) )
unlabeled->push_back( mLabelPositions[ startIndexForLabelPlacements ].get() );
}
}

@@ -687,7 +692,7 @@ QList<LabelPosition *> Problem::getSolution( bool returnInactive, QList<LabelPos
unlabeled->append( position.get() );
}

return solList;
return finalLabelPlacements;
}

void Problem::solution_cost()
@@ -89,6 +89,7 @@ class TestQgsLabelingEngine : public QObject
void testLineAnchorCurvedConstraints();
void testLineAnchorHorizontal();
void testLineAnchorHorizontalConstraints();
void testShowAllLabelsWhenALabelHasNoCandidates();

private:
QgsVectorLayer *vl = nullptr;
@@ -3212,5 +3213,67 @@ void TestQgsLabelingEngine::testLineAnchorHorizontalConstraints()
QVERIFY( imageCheck( QStringLiteral( "horizontal_strict_anchor_end" ), img, 20 ) );
}

void TestQgsLabelingEngine::testShowAllLabelsWhenALabelHasNoCandidates()
{
// test that showing all labels when a label has no candidate placements doesn't
// result in a crash
// refs https://github.com/qgis/QGIS/issues/38093

QgsPalLayerSettings settings;
setDefaultLabelParams( settings );

QgsTextFormat format = settings.format();
format.setSize( 20 );
format.setColor( QColor( 0, 0, 0 ) );
settings.setFormat( format );

settings.fieldName = QStringLiteral( "'xxxxxxxxxxxxxx'" );
settings.isExpression = true;
settings.placement = QgsPalLayerSettings::Line;
settings.lineSettings().setPlacementFlags( QgsLabeling::LinePlacementFlag::OnLine );
settings.obstacleSettings().setFactor( 10 );
settings.lineSettings().setOverrunDistance( 50 );

std::unique_ptr< QgsVectorLayer> vl2( new QgsVectorLayer( QStringLiteral( "LineString?crs=epsg:23700&field=l:string" ), QStringLiteral( "vl" ), QStringLiteral( "memory" ) ) );
vl2->setRenderer( new QgsNullSymbolRenderer() );

QgsFeature f;
f.setAttributes( QgsAttributes() << QVariant() );

f.setGeometry( QgsGeometry::fromWkt( QStringLiteral( "LineString (-2446233 -5204828, -2342845 -5203825)" ) ) );
QVERIFY( vl2->dataProvider()->addFeature( f ) );

f.setGeometry( QgsGeometry::fromWkt( QStringLiteral( "LineString (-2439207 -5198806, -2331302 -5197802)" ) ) );
QVERIFY( vl2->dataProvider()->addFeature( f ) );

vl2->setLabeling( new QgsVectorLayerSimpleLabeling( settings ) ); // TODO: this should not be necessary!
vl2->setLabelsEnabled( true );

// make a fake render context
QSize size( 640, 480 );
QgsMapSettings mapSettings;
mapSettings.setLabelingEngineSettings( createLabelEngineSettings() );
mapSettings.setDestinationCrs( vl2->crs() );

mapSettings.setOutputSize( size );
mapSettings.setExtent( QgsRectangle( -3328044.9, -5963176., -1127782.7, -4276844.3 ) );
mapSettings.setLayers( QList<QgsMapLayer *>() << vl2.get() );
mapSettings.setOutputDpi( 96 );

QgsLabelingEngineSettings engineSettings = mapSettings.labelingEngineSettings();
engineSettings.setFlag( QgsLabelingEngineSettings::DrawLabelRectOnly, true );
engineSettings.setFlag( QgsLabelingEngineSettings::UseAllLabels, true );
engineSettings.setFlag( QgsLabelingEngineSettings::DrawUnplacedLabels, true );
// engineSettings.setFlag( QgsLabelingEngineSettings::DrawCandidates, true );
mapSettings.setLabelingEngineSettings( engineSettings );

QgsMapRendererSequentialJob job( mapSettings );
job.start();
job.waitForFinished();

QImage img = job.renderedImage();
QVERIFY( imageCheck( QStringLiteral( "show_all_labels_when_no_candidates" ), img, 20 ) );
}

QGSTEST_MAIN( TestQgsLabelingEngine )
#include "testqgslabelingengine.moc"
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