#9480: Force label position inside of polygons in PAL labeling library

qgis · May 27, 2014 · 1e54a46 · 1e54a46
1 parent 72b3d3f
commit 1e54a46
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Showing 6 changed files with 40 additions and 4 deletions.
diff --git a/src/core/pal/feature.cpp b/src/core/pal/feature.cpp
@@ -1344,7 +1344,7 @@ namespace pal
             case P_POINT:
             case P_POINT_OVER:
               double cx, cy;
-              mapShape->getCentroid( cx, cy );
+              mapShape->getCentroid( cx, cy, f->layer->getCentroidInside() );
               if ( f->layer->getArrangement() == P_POINT_OVER )
                 nbp = setPositionOverPoint( cx, cy, scale, lPos, delta, angle );
               else

diff --git a/src/core/pal/layer.cpp b/src/core/pal/layer.cpp
@@ -61,7 +61,7 @@ namespace pal
 
   Layer::Layer( const char *lyrName, double min_scale, double max_scale, Arrangement arrangement, Units label_unit, double defaultPriority, bool obstacle, bool active, bool toLabel, Pal *pal, bool displayAll )
       :  pal( pal ), obstacle( obstacle ), active( active ),
-      toLabel( toLabel ), displayAll( displayAll ), label_unit( label_unit ),
+      toLabel( toLabel ), displayAll( displayAll ), centroidInside( false ), label_unit( label_unit ),
       min_scale( min_scale ), max_scale( max_scale ),
       arrangement( arrangement ), arrangementFlags( 0 ), mode( LabelPerFeature ), mergeLines( false )
   {

diff --git a/src/core/pal/layer.h b/src/core/pal/layer.h
@@ -101,6 +101,7 @@ namespace pal
       bool active;
       bool toLabel;
       bool displayAll;
+      bool centroidInside;
 
       Units label_unit;
 
@@ -291,6 +292,9 @@ namespace pal
       void setUpsidedownLabels( UpsideDownLabels ud ) { upsidedownLabels = ud; }
       UpsideDownLabels getUpsidedownLabels() const { return upsidedownLabels; }
 
+      void setCentroidInside( bool forceInside ) { centroidInside = forceInside; }
+      bool getCentroidInside() const { return centroidInside; }
+
       /**
        * \brief register a feature in the layer
        *

diff --git a/src/core/pal/pointset.cpp b/src/core/pal/pointset.cpp
@@ -956,7 +956,7 @@ namespace pal
 
 
 
-  void PointSet::getCentroid( double &px, double &py )
+  void PointSet::getCentroid( double &px, double &py, bool forceInside )
   {
     // for explanation see this page:
     // http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/
@@ -984,6 +984,35 @@ namespace pal
       px = cx / ( 3 * A ) + x[0];
       py = cy / ( 3 * A ) + y[0];
     }
+
+    // check if centroid inside in polygon
+    if ( forceInside && !isPointInPolygon( nbPoints, x, y, px, py ) )
+    {
+      GEOSCoordSequence *coord = GEOSCoordSeq_create( nbPoints, 2 );
+
+      for ( int i = 0; i < nbPoints; ++i )
+      {
+        GEOSCoordSeq_setX( coord, i, x[i] );
+        GEOSCoordSeq_setY( coord, i, y[i] );
+      }
+
+      GEOSGeometry *geom = GEOSGeom_createPolygon( GEOSGeom_createLinearRing( coord ), 0, 0 );
+
+      if ( geom )
+      {
+        GEOSGeometry *pointGeom = GEOSPointOnSurface( geom );
+
+        if ( pointGeom )
+        {
+          const GEOSCoordSequence *coordSeq = GEOSGeom_getCoordSeq( pointGeom );
+          GEOSCoordSeq_getX( coordSeq, 0, &px );
+          GEOSCoordSeq_getY( coordSeq, 0, &py );
+
+          GEOSGeom_destroy( pointGeom );
+        }
+        GEOSGeom_destroy( geom );
+      }
+    }
   }
 
 } // end namespace

diff --git a/src/core/pal/pointset.h b/src/core/pal/pointset.h
@@ -160,7 +160,7 @@ namespace pal
 
       //double getDistInside(double px, double py);
 
-      void getCentroid( double &px, double &py );
+      void getCentroid( double &px, double &py, bool forceInside = false );
 
 
       int getGeosType() const { return type; }

diff --git a/src/core/qgspallabeling.cpp b/src/core/qgspallabeling.cpp
@@ -3389,6 +3389,9 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
   // set whether adjacent lines should be merged
   l->setMergeConnectedLines( lyr.mergeLines );
 
+  // force the location of the centroid inside of polygons
+  l->setCentroidInside( true );
+
   // set how to show upside-down labels
   Layer::UpsideDownLabels upsdnlabels;
   switch ( lyr.upsidedownLabels )