[labeling] Fix minimum feature size settings not taking merged lines …

…into account
qgis · Apr 7, 2021 · 7dd97e6 · 7dd97e6
1 parent ad1b06d
commit 7dd97e6
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Showing 3 changed files with 42 additions and 2 deletions.
diff --git a/src/core/labeling/qgslabelfeature.h b/src/core/labeling/qgslabelfeature.h
@@ -530,6 +530,24 @@ class CORE_EXPORT QgsLabelFeature
      */
     void setOriginalFeatureCrs( const QgsCoordinateReferenceSystem &crs );
 
+    /**
+     * Returns the minimum size (in map unit) for a feature to be labelled.
+     *
+     * \note At the moment this is only used when labeling merged lines
+     * \see minimumSize()
+     * \since QGIS 3.20
+     */
+    double minimumSize() const { return mMinimumSize; }
+
+    /**
+     * Sets the minimum \a size (in map unit) for a feature to be labelled.
+     *
+     * \note At the moment this is only used when labeling merged lines
+     * \see setMinimumSize()
+     * \since QGIS 3.20
+     */
+    void setMinimumSize( double size ) { mMinimumSize = size; }
+
   protected:
     //! Pointer to PAL layer (assigned when registered to PAL)
     pal::Layer *mLayer = nullptr;
@@ -611,6 +629,9 @@ class CORE_EXPORT QgsLabelFeature
     QgsLabelLineSettings::AnchorType mLineAnchorType = QgsLabelLineSettings::AnchorType::HintOnly;
 
     QgsCoordinateReferenceSystem mOriginalFeatureCrs;
+
+    double mMinimumSize = 0.0;
+
 };
 
 #endif // QGSLABELFEATURE_H
diff --git a/src/core/labeling/qgspallabeling.cpp b/src/core/labeling/qgspallabeling.cpp
@@ -2104,8 +2104,20 @@ void QgsPalLayerSettings::registerFeature( const QgsFeature &f, QgsRenderContext
   QgsLabelThinningSettings featureThinningSettings = mThinningSettings;
   featureThinningSettings.updateDataDefinedProperties( mDataDefinedProperties, context.expressionContext() );
 
-  if ( featureThinningSettings.minimumFeatureSize() > 0 && !checkMinimumSizeMM( context, geom, featureThinningSettings.minimumFeatureSize() ) )
-    return;
+  double minimumSize = 0.0;
+  if ( featureThinningSettings.minimumFeatureSize() > 0 )
+  {
+    // for minimum feature size on merged lines, we need to delay the filtering after the merging occurred in PAL
+    if ( geom.type() == QgsWkbTypes::LineGeometry && mLineSettings.mergeLines() )
+    {
+      minimumSize = context.convertToMapUnits( featureThinningSettings.minimumFeatureSize(), QgsUnitTypes::RenderMillimeters );
+    }
+    else
+    {
+      if ( !checkMinimumSizeMM( context, geom, featureThinningSettings.minimumFeatureSize() ) )
+        return;
+    }
+  }
 
   if ( !geos_geom_clone )
     return; // invalid geometry
@@ -2493,6 +2505,7 @@ void QgsPalLayerSettings::registerFeature( const QgsFeature &f, QgsRenderContext
   ( *labelFeature )->setLineAnchorType( lineSettings.anchorType() );
   ( *labelFeature )->setLabelAllParts( labelAll );
   ( *labelFeature )->setOriginalFeatureCrs( context.coordinateTransform().sourceCrs() );
+  ( *labelFeature )->setMinimumSize( minimumSize );
   if ( geom.type() == QgsWkbTypes::PointGeometry && !obstacleGeometry.isNull() )
   {
     //register symbol size

diff --git a/src/core/pal/layer.cpp b/src/core/pal/layer.cpp
@@ -338,6 +338,12 @@ void Layer::joinConnectedFeatures()
     }
   }
   mConnectedHashtable.clear();
+
+  // Expunge feature parts that are smaller than the minimum size required
+  mFeatureParts.erase( std::remove_if( mFeatureParts.begin(), mFeatureParts.end(), []( FeaturePart * part )
+  {
+    return part->feature()->minimumSize() != 0.0 && part->length() < part->feature()->minimumSize();
+  } ), mFeatureParts.end() );
 }
 
 int Layer::connectedFeatureId( QgsFeatureId featureId ) const