[labeling] Avoid placing labels over ANY part of point symbols

Author: nyalldawson

python/core/qgspallabeling.sip

@@ -152,8 +152,12 @@ class QgsPalLayerSettings
     {
       PolygonInterior, /*!< avoid placing labels over interior of polygon (prefer placing labels totally
        outside or just slightly inside polygon) */
-      PolygonBoundary /*!< avoid placing labels over boundary of polygon (prefer placing outside or
+      PolygonBoundary, /*!< avoid placing labels over boundary of polygon (prefer placing outside or
        completely inside polygon) */
+      PolygonWhole /*!< avoid placing labels over ANY part of polygon. Where PolygonInterior will prefer
+       to place labels with the smallest area of intersection between the label and the polygon,
+       PolygonWhole will penalise any label which intersects with the polygon by an equal amount, so that
+       placing labels over any part of the polygon is avoided.*/
     };
 
     enum ShapeType

src/core/pal/costcalculator.cpp

@@ -77,6 +77,10 @@ namespace pal
             // penalty may need tweaking, given that interior mode ranges up to 12
             n = ( lp->crossesBoundary( obstacle ) ? 6 : 0 );
             break;
+          case PolygonWhole:
+            // n is either 0 or 12
+            n = ( lp->intersectsWithPolygon( obstacle ) ? 12 : 0 );
+            break;
         }
 
         break;

src/core/pal/labelposition.cpp

@@ -590,6 +590,37 @@ namespace pal
     return ceil( totalCost / n );
   }
 
+  bool LabelPosition::intersectsWithPolygon( PointSet* polygon ) const
+  {
+    if ( !mGeos )
+      createGeosGeom();
+
+    if ( !polygon->mGeos )
+      polygon->createGeosGeom();
+
+    GEOSContextHandle_t geosctxt = geosContext();
+    try
+    {
+      if ( GEOSPreparedIntersects_r( geosctxt, polygon->preparedGeom(), mGeos ) == 1 )
+      {
+        return true;
+      }
+    }
+    catch ( GEOSException &e )
+    {
+      QgsMessageLog::logMessage( QObject::tr( "Exception: %1" ).arg( e.what() ), QObject::tr( "GEOS" ) );
+    }
+
+    if ( nextPart )
+    {
+      return nextPart->intersectsWithPolygon( polygon );
+    }
+    else
+    {
+      return false;
+    }
+  }
+
   double LabelPosition::polygonIntersectionCostForParts( PointSet *polygon ) const
   {
     if ( !mGeos )

src/core/pal/labelposition.h

@@ -140,6 +140,10 @@ namespace pal
        */
       int polygonIntersectionCost( PointSet* polygon ) const;
 
+      /** Returns true if if any intersection between polygon and position exists.
+      */
+      bool intersectsWithPolygon( PointSet* polygon ) const;
+
       /** Shift the label by specified offset */
       void offsetPosition( double xOffset, double yOffset );
 

src/core/pal/pal.h

@@ -89,7 +89,8 @@ namespace pal
   enum ObstacleType
   {
     PolygonInterior,
-    PolygonBoundary
+    PolygonBoundary,
+    PolygonWhole
   };
 
   /**

src/core/qgslabelingenginev2.cpp

@@ -110,6 +110,9 @@ void QgsLabelingEngineV2::processProvider( QgsAbstractLabelProvider* provider, Q
     case QgsPalLayerSettings::PolygonBoundary:
       l->setObstacleType( pal::PolygonBoundary );
       break;
+    case QgsPalLayerSettings::PolygonWhole:
+      l->setObstacleType( pal::PolygonWhole );
+      break;
   }
 
   // set whether location of centroid must be inside of polygons

src/core/qgspallabeling.h

@@ -134,8 +134,12 @@ class CORE_EXPORT QgsPalLayerSettings
     {
       PolygonInterior, /*!< avoid placing labels over interior of polygon (prefer placing labels totally
        outside or just slightly inside polygon) */
-      PolygonBoundary /*!< avoid placing labels over boundary of polygon (prefer placing outside or
+      PolygonBoundary, /*!< avoid placing labels over boundary of polygon (prefer placing outside or
        completely inside polygon) */
+      PolygonWhole /*!< avoid placing labels over ANY part of polygon. Where PolygonInterior will prefer
+       to place labels with the smallest area of intersection between the label and the polygon,
+       PolygonWhole will penalise any label which intersects with the polygon by an equal amount, so that
+       placing labels over any part of the polygon is avoided.*/
     };
 
     enum ShapeType

src/core/qgsvectorlayerlabelprovider.cpp

@@ -52,6 +52,7 @@ static void _fixQPictureDPI( QPainter* p )
 QgsVectorLayerLabelProvider::QgsVectorLayerLabelProvider( QgsVectorLayer* layer, bool withFeatureLoop, const QgsPalLayerSettings* settings, const QString& layerName )
     : mSettings( settings ? *settings : QgsPalLayerSettings::fromLayer( layer ) )
     , mLayerId( layer->id() )
+    , mLayerGeometryType( layer->geometryType() )
     , mRenderer( layer->rendererV2() )
     , mFields( layer->fields() )
     , mCrs( layer->crs() )
@@ -80,6 +81,7 @@ QgsVectorLayerLabelProvider::QgsVectorLayerLabelProvider( const QgsPalLayerSetti
     bool ownsSource, QgsFeatureRendererV2* renderer )
     : mSettings( settings )
     , mLayerId( layerId )
+    , mLayerGeometryType( QGis::UnknownGeometry )
     , mRenderer( renderer )
     , mFields( fields )
     , mCrs( crs )
@@ -102,7 +104,17 @@ void QgsVectorLayerLabelProvider::init()
   if ( mSettings.fitInPolygonOnly ) mFlags |= FitInPolygonOnly;
   if ( mSettings.labelPerPart ) mFlags |= LabelPerFeaturePart;
   mPriority = 1 - mSettings.priority / 10.0; // convert 0..10 --> 1..0
-  mObstacleType = mSettings.obstacleType;
+
+  if ( mLayerGeometryType == QGis::Point && mRenderer )
+  {
+    //override obstacle type to treat any intersection of a label with the point symbol as a high cost conflict
+    mObstacleType = QgsPalLayerSettings::PolygonWhole;
+  }
+  else
+  {
+    mObstacleType = mSettings.obstacleType;
+  }
+
   mUpsidedownLabels = mSettings.upsidedownLabels;
 }
 

src/core/qgsvectorlayerlabelprovider.h

@@ -94,6 +94,8 @@ class CORE_EXPORT QgsVectorLayerLabelProvider : public QgsAbstractLabelProvider
     QgsPalLayerSettings mSettings;
     //! Layer's ID
     QString mLayerId;
+    //! Geometry type of layer
+    QGis::GeometryType mLayerGeometryType;
 
     QgsFeatureRendererV2* mRenderer;