Allow setting label obstacle geom in QgsPalLabeling::registerFeature

Sponsored by City of Uster

Author: nyalldawson

python/core/qgspallabeling.sip

@@ -492,6 +492,13 @@ class QgsPalLayerSettings
      * @param context render context. The QgsExpressionContext contained within the render context
      * must have already had the feature and fields sets prior to calling this method.
      * @param dxfLayer dxfLayer name
+     * @param labelFeature if using QgsLabelingEngineV2, this will receive the label feature. Not available
+     * in Python bindings.
+     * @param obstacleGeometry optional obstacle geometry, if a different geometry to the feature's geometry
+     * should be used as an obstacle for labels (eg, if the feature has been rendered with an offset point
+     * symbol, the obstacle geometry should represent the bounds of the offset symbol). If not set,
+     * the feature's original geometry will be used as an obstacle for labels. Not available
+     * in Python bindings.
      */
     void registerFeature( QgsFeature& f, QgsRenderContext& context, const QString& dxfLayer );
 

src/core/qgspallabeling.cpp

@@ -1896,25 +1896,32 @@ void QgsPalLayerSettings::calculateLabelSize( const QFontMetricsF* fm, QString t
 #endif
 }
 
-
-void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** labelFeature )
+void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** labelFeature , QgsGeometry* obstacleGeometry )
 {
   // either used in QgsPalLabeling (palLayer is set) or in QgsLabelingEngineV2 (labelFeature is set)
   Q_ASSERT( labelFeature );
 
   Q_UNUSED( dxfLayer ); // now handled in QgsDxfLabelProvider
 
+  QVariant exprVal; // value() is repeatedly nulled on data defined evaluation and replaced when successful
+  mCurFeat = &f;
+
+  // data defined is obstacle? calculate this first, to avoid wasting time working with obstacles we don't require
+  bool isObstacle = obstacle; // start with layer default
+  if ( dataDefinedEvaluate( QgsPalLayerSettings::IsObstacle, exprVal, &context.expressionContext(), obstacle ) )
+  {
+    isObstacle = exprVal.toBool();
+  }
+
   if ( !drawLabels )
   {
-    if ( obstacle )
+    if ( isObstacle )
     {
-      registerObstacleFeature( f, context, QString(), labelFeature );
+      registerObstacleFeature( f, context, QString(), labelFeature, obstacleGeometry );
     }
     return;
   }
 
-  QVariant exprVal; // value() is repeatedly nulled on data defined evaluation and replaced when successful
-  mCurFeat = &f;
 //  mCurFields = &layer->pendingFields();
 
   // store data defined-derived values for later adding to label feature for use during rendering
@@ -2237,7 +2244,6 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   const GEOSGeometry* geos_geom = 0;
   const QgsGeometry* preparedGeom = geom;
   QScopedPointer<QgsGeometry> scopedPreparedGeom;
-
   if ( QgsPalLabeling::geometryRequiresPreparation( geom, context, ct, doClip ? extentGeom : 0 ) )
   {
     scopedPreparedGeom.reset( QgsPalLabeling::prepareGeometry( geom, context, ct, doClip ? extentGeom : 0 ) );
@@ -2250,6 +2256,22 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   {
     geos_geom = geom->asGeos();
   }
+  const GEOSGeometry* geosObstacleGeom = 0;
+  const QgsGeometry* preparedObstacleGeom = obstacleGeometry;
+  QScopedPointer<QgsGeometry> scopedObstacleGeom;
+  if ( isObstacle )
+  {
+    if ( obstacleGeometry && QgsPalLabeling::geometryRequiresPreparation( obstacleGeometry, context, ct, doClip ? extentGeom : 0 ) )
+    {
+      scopedObstacleGeom.reset( QgsPalLabeling::prepareGeometry( obstacleGeometry, context, ct, doClip ? extentGeom : 0 ) );
+      preparedObstacleGeom = scopedObstacleGeom.data();
+      geosObstacleGeom = scopedObstacleGeom.data()->asGeos();
+    }
+    else if ( obstacleGeometry )
+    {
+      geosObstacleGeom = obstacleGeometry->asGeos();
+    }
+  }
 
   if ( minFeatureSize > 0 && !checkMinimumSizeMM( context, preparedGeom, minFeatureSize ) )
     return;
@@ -2291,6 +2313,12 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   {
     geos_geom_clone = GEOSGeom_clone_r( QgsGeometry::getGEOSHandler(), geos_geom );
   }
+  GEOSGeometry* geosObstacleGeomClone = 0;
+  if ( geosObstacleGeom )
+  {
+    geosObstacleGeomClone = GEOSGeom_clone_r( QgsGeometry::getGEOSHandler(), geosObstacleGeom );
+  }
+
 
   //data defined position / alignment / rotation?
   bool dataDefinedPosition = false;
@@ -2610,6 +2638,10 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   ( *labelFeature )->setAlwaysShow( alwaysShow );
   ( *labelFeature )->setRepeatDistance( repeatDist );
   ( *labelFeature )->setLabelText( labelText );
+  if ( geosObstacleGeomClone )
+  {
+    ( *labelFeature )->setObstacleGeometry( geosObstacleGeomClone );
+  }
 
   // store the label's calculated font for later use during painting
   QgsDebugMsgLevel( QString( "PAL font stored definedFont: %1, Style: %2" ).arg( labelFont.toString(), labelFont.styleName() ), 4 );
@@ -2678,13 +2710,6 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
     }
   }
 
-  // data defined is obstacle?
-  bool isObstacle = obstacle; // start with layer default
-  if ( dataDefinedEvaluate( QgsPalLayerSettings::IsObstacle, exprVal, &context.expressionContext(), obstacle ) )
-  {
-    isObstacle = exprVal.toBool();
-  }
-
   ( *labelFeature )->setIsObstacle( isObstacle );
 
   double featObstacleFactor = obstacleFactor;
@@ -2705,14 +2730,22 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   lf->setDataDefinedValues( dataDefinedValues );
 }
 
-
-void QgsPalLayerSettings::registerObstacleFeature( QgsFeature& f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** obstacleFeature )
+void QgsPalLayerSettings::registerObstacleFeature( QgsFeature& f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** obstacleFeature, QgsGeometry* obstacleGeometry )
 {
   Q_UNUSED( dxfLayer ); // now handled in QgsDxfLabelProvider
 
   mCurFeat = &f;
 
-  const QgsGeometry* geom = f.constGeometry();
+  const QgsGeometry* geom = 0;
+  if ( obstacleGeometry )
+  {
+    geom = obstacleGeometry;
+  }
+  else
+  {
+    geom = f.constGeometry();
+  }
+
   if ( !geom )
   {
     return;

src/core/qgspallabeling.h

@@ -474,9 +474,15 @@ class CORE_EXPORT QgsPalLayerSettings
      * @param context render context. The QgsExpressionContext contained within the render context
      * must have already had the feature and fields sets prior to calling this method.
      * @param dxfLayer dxfLayer name
-     * @param labelFeature if using QgsLabelingEngineV2, this will receive the label feature
+     * @param labelFeature if using QgsLabelingEngineV2, this will receive the label feature. Not available
+     * in Python bindings.
+     * @param obstacleGeometry optional obstacle geometry, if a different geometry to the feature's geometry
+     * should be used as an obstacle for labels (eg, if the feature has been rendered with an offset point
+     * symbol, the obstacle geometry should represent the bounds of the offset symbol). If not set,
+     * the feature's original geometry will be used as an obstacle for labels. Not available
+     * in Python bindings.
      */
-    void registerFeature( QgsFeature& f, QgsRenderContext& context, const QString& dxfLayer, QgsLabelFeature** labelFeature = 0 );
+    void registerFeature( QgsFeature& f, QgsRenderContext& context, const QString& dxfLayer, QgsLabelFeature** labelFeature = 0, QgsGeometry* obstacleGeometry = 0 );
 
     void readFromLayer( QgsVectorLayer* layer );
     void writeToLayer( QgsVectorLayer* layer );
@@ -644,7 +650,7 @@ class CORE_EXPORT QgsPalLayerSettings
 
     /** Registers a feature as an obstacle only (no label rendered)
      */
-    void registerObstacleFeature( QgsFeature &f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** obstacleFeature );
+    void registerObstacleFeature( QgsFeature &f, QgsRenderContext &context, const QString& dxfLayer, QgsLabelFeature** obstacleFeature, QgsGeometry* obstacleGeometry = 0 );
 
     QMap<DataDefinedProperties, QVariant> dataDefinedValues;
     QgsExpression* expression;