Merge pull request #32706 from m-kuhn/qgis_point_pattern_fill_fix

Fix freeze when loading point pattern fill with distance 0

src/core/symbology/qgsfillsymbollayer.cpp

@@ -3183,7 +3183,11 @@ void QgsPointPatternFillSymbolLayer::applyPattern( const QgsSymbolRenderContext
 
   QImage patternImage( width, height, QImage::Format_ARGB32 );
   patternImage.fill( 0 );
-
+  if ( patternImage.isNull() )
+  {
+    brush.setTextureImage( QImage() );
+    return;
+  }
   if ( mMarkerSymbol )
   {
     QPainter p( &patternImage );

src/core/symbology/qgssymbol.cpp

@@ -527,8 +527,7 @@ void QgsSymbol::drawPreviewIcon( QPainter *painter, QSize size, QgsRenderContext
     context->setExpressionContext( expContext );
   }
 
-  const auto constMLayers = mLayers;
-  for ( QgsSymbolLayer *layer : constMLayers )
+  for ( QgsSymbolLayer *layer : qgis::as_const( mLayers ) )
   {
     if ( !layer->enabled()  || ( customContext && !customContext->isSymbolLayerEnabled( layer ) ) )
       continue;

tests/src/core/testqgspointpatternfillsymbol.cpp

@@ -56,6 +56,7 @@ class TestQgsPointPatternFillSymbol : public QObject
     void pointPatternFillSymbol();
     void offsettedPointPatternFillSymbol();
     void dataDefinedSubSymbol();
+    void zeroSpacedPointPatternFillSymbol();
 
   private:
     bool mTestHasError =  false ;
@@ -185,6 +186,25 @@ void TestQgsPointPatternFillSymbol::dataDefinedSubSymbol()
   QVERIFY( imageCheck( "datadefined_subsymbol" ) );
 }
 
+void TestQgsPointPatternFillSymbol::zeroSpacedPointPatternFillSymbol()
+{
+  mReport += QLatin1String( "<h2>Zero distance point pattern fill symbol renderer test</h2>\n" );
+
+  QgsStringMap properties;
+  properties.insert( QStringLiteral( "color" ), QStringLiteral( "0,0,0,255" ) );
+  properties.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
+  properties.insert( QStringLiteral( "name" ), QStringLiteral( "circle" ) );
+  properties.insert( QStringLiteral( "size" ), QStringLiteral( "5.0" ) );
+  QgsMarkerSymbol *pointSymbol = QgsMarkerSymbol::createSimple( properties );
+
+  mPointPatternFill->setSubSymbol( pointSymbol );
+  mPointPatternFill->setDistanceX( 0 );
+  mPointPatternFill->setDistanceY( 15 );
+  mPointPatternFill->setOffsetX( 4 );
+  mPointPatternFill->setOffsetY( 4 );
+  QVERIFY( imageCheck( "pointfill_zero_space" ) );
+}
+
 //
 // Private helper functions not called directly by CTest
 //