Ensure that the @geometry_part_num variable exactly matches the

correct part ordering for polygon features Because we sort and render polygon parts in descending area order, we can't use the order of parts rendered for this variable or we'll be giving a different part number vs the actual geometry part number.
qgis · Mar 31, 2021 · 684a422 · 684a422
1 parent 2a1ab9b
commit 684a422
Show file tree

Hide file tree

Showing 3 changed files with 29 additions and 9 deletions.
diff --git a/src/core/symbology/qgssymbol.cpp b/src/core/symbology/qgssymbol.cpp
@@ -1012,11 +1012,12 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
     QPolygonF renderExterior;
     QVector< QPolygonF > renderRings;
     const QgsCurvePolygon *originalGeometry = nullptr;
+    int originalPartIndex = 0;
   };
   QVector< PolygonInfo > polygonsToRender;
 
-  std::function< void ( const QgsAbstractGeometry * )> getPartGeometry;
-  getPartGeometry = [&pointsToRender, &linesToRender, &polygonsToRender, &getPartGeometry, &context, &clippingEnabled, &markers, &feature, &usingSegmentizedGeometry, this]( const QgsAbstractGeometry * part )
+  std::function< void ( const QgsAbstractGeometry *, int partIndex )> getPartGeometry;
+  getPartGeometry = [&pointsToRender, &linesToRender, &polygonsToRender, &getPartGeometry, &context, &clippingEnabled, &markers, &feature, &usingSegmentizedGeometry, this]( const QgsAbstractGeometry * part, int partIndex = 0 )
   {
     Q_UNUSED( feature )
 
@@ -1138,6 +1139,7 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
 
         PolygonInfo info;
         info.originalGeometry = qgsgeometry_cast<const QgsCurvePolygon *>( part );
+        info.originalPartIndex = partIndex;
         if ( !qgsgeometry_cast<const QgsPolygon *>( processedGeometry )->exteriorRing() )
         {
           QgsDebugMsg( QStringLiteral( "cannot render polygon with no exterior ring" ) );
@@ -1167,7 +1169,7 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
           if ( context.renderingStopped() )
             break;
 
-          getPartGeometry( geomCollection->geometryN( i ) );
+          getPartGeometry( geomCollection->geometryN( i ), i );
         }
         break;
       }
@@ -1205,7 +1207,7 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
           for ( int idx = 0; idx < listPartIndex.size(); ++idx )
           {
             const unsigned i = listPartIndex[idx];
-            getPartGeometry( geomCollection->geometryN( i ) );
+            getPartGeometry( geomCollection->geometryN( i ), i );
           }
         }
         break;
@@ -1219,7 +1221,7 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
     }
   };
 
-  getPartGeometry( geom.constGet() );
+  getPartGeometry( geom.constGet(), 0 );
 
   // step 2 - determine which layers to render
   std::vector< int > layers;
@@ -1295,19 +1297,17 @@ void QgsSymbol::renderFeature( const QgsFeature &feature, QgsRenderContext &cont
 
       case QgsSymbol::Fill:
       {
-        int geometryPartNumber = 0;
         for ( const PolygonInfo &info : std::as_const( polygonsToRender ) )
         {
           if ( context.renderingStopped() )
             break;
 
-          mSymbolRenderContext->setGeometryPartNum( geometryPartNumber + 1 );
+          mSymbolRenderContext->setGeometryPartNum( info.originalPartIndex + 1 );
           if ( needsExpressionContext )
-            mSymbolRenderContext->expressionContextScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_PART_NUM, geometryPartNumber + 1, true ) );
+            mSymbolRenderContext->expressionContextScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_PART_NUM, info.originalPartIndex + 1, true ) );
 
           context.setGeometry( info.originalGeometry );
           static_cast<QgsFillSymbol *>( this )->renderPolygon( info.renderExterior, ( !info.renderRings.isEmpty() ? &info.renderRings : nullptr ), &feature, context, symbolLayerIndex, selected );
-          geometryPartNumber++;
         }
 
         break;

diff --git a/tests/src/python/test_qgsmarkerlinesymbollayer.py b/tests/src/python/test_qgsmarkerlinesymbollayer.py
@@ -186,6 +186,26 @@ def testPartNum(self):
         rendered_image = self.renderGeometry(s, g, buffer=4)
         assert self.imageCheck('part_count_variable', 'part_count_variable', rendered_image)
 
+    def testPartNumPolygon(self):
+        # test geometry_part_num variable
+        s = QgsFillSymbol()
+
+        marker_line = QgsMarkerLineSymbolLayer(False)
+        marker_line.setPlacement(QgsMarkerLineSymbolLayer.FirstVertex)
+        f = QgsFontUtils.getStandardTestFont('Bold', 24)
+        marker = QgsFontMarkerSymbolLayer(f.family(), 'x', 24, QColor(255, 255, 0))
+        marker.setDataDefinedProperty(QgsSymbolLayer.PropertyCharacter, QgsProperty.fromExpression('@geometry_part_num'))
+        marker_symbol = QgsMarkerSymbol()
+        marker_symbol.changeSymbolLayer(0, marker)
+        marker_line.setSubSymbol(marker_symbol)
+        marker_line.setAverageAngleLength(0)
+        s.changeSymbolLayer(0, marker_line)
+
+        # rendering test - a polygon with a smaller part first
+        g = QgsGeometry.fromWkt('MultiPolygon(((0 0, 2 0, 2 2, 0 0)),((10 0, 10 10, 0 10, 10 0)))')
+        rendered_image = self.renderGeometry(s, g, buffer=4)
+        assert self.imageCheck('poly_part_num_variable', 'poly_part_num_variable', rendered_image)
+
     def testCompoundCurve(self):
         # test rendering compound curve with markers at vertices and curve points
         s = QgsLineSymbol()

diff --git a/..._markerline/expected_poly_part_num_variable/expected_poly_part_num_variable.png b/..._markerline/expected_poly_part_num_variable/expected_poly_part_num_variable.png