Ensure that project colors show correctly in legend and symbol previews

qgis · Jan 12, 2019 · 0f42c8e · 0f42c8e
1 parent ac10769
commit 0f42c8e
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Showing 4 changed files with 28 additions and 2 deletions.
diff --git a/src/core/layertree/qgslayertreemodellegendnode.cpp b/src/core/layertree/qgslayertreemodellegendnode.cpp
@@ -393,6 +393,11 @@ QSizeF QgsSymbolLegendNode::drawSymbol( const QgsLegendSettings &settings, ItemC
   context.setForceVectorOutput( true );
   context.setPainter( ctx ? ctx->painter : nullptr );
 
+  // use a minimal expression context for now
+  QgsExpressionContext expContext;
+  expContext.appendScopes( QgsExpressionContextUtils::globalProjectLayerScopes( nullptr ) );
+  context.setExpressionContext( expContext );
+
   //Consider symbol size for point markers
   double height = settings.symbolSize().height();
   double width = settings.symbolSize().width();

diff --git a/src/core/layout/qgslayoutitemlegend.cpp b/src/core/layout/qgslayoutitemlegend.cpp
@@ -47,6 +47,13 @@ QgsLayoutItemLegend::QgsLayoutItemLegend( QgsLayout *layout )
   // Connect to the main layertreeroot.
   // It serves in "auto update mode" as a medium between the main app legend and this one
   connect( mLayout->project()->layerTreeRoot(), &QgsLayerTreeNode::customPropertyChanged, this, &QgsLayoutItemLegend::nodeCustomPropertyChanged );
+
+  // If project colors change, we need to redraw legend, as legend symbols may rely on project colors
+  connect( mLayout->project(), &QgsProject::projectColorsChanged, this, [ = ]
+  {
+    invalidateCache();
+    update();
+  } );
 }
 
 QgsLayoutItemLegend *QgsLayoutItemLegend::create( QgsLayout *layout )

diff --git a/src/core/symbology/qgssymbol.cpp b/src/core/symbology/qgssymbol.cpp
@@ -474,6 +474,14 @@ void QgsSymbol::drawPreviewIcon( QPainter *painter, QSize size, QgsRenderContext
   QgsSymbolRenderContext symbolContext( context, outputUnit(), mOpacity, false, mRenderHints, nullptr, QgsFields(), mapUnitScale() );
   symbolContext.setOriginalGeometryType( mType == Fill ? QgsWkbTypes::PolygonGeometry : QgsWkbTypes::UnknownGeometry );
 
+  if ( !customContext )
+  {
+    // if no render context was passed, build a minimal expression context
+    QgsExpressionContext expContext;
+    expContext.appendScopes( QgsExpressionContextUtils::globalProjectLayerScopes( nullptr ) );
+    context.setExpressionContext( expContext );
+  }
+
   Q_FOREACH ( QgsSymbolLayer *layer, mLayers )
   {
     if ( !layer->enabled() )

diff --git a/src/core/symbology/qgssymbollayerutils.cpp b/src/core/symbology/qgssymbollayerutils.cpp
@@ -672,7 +672,7 @@ QPixmap QgsSymbolLayerUtils::symbolPreviewPixmap( QgsSymbol *symbol, QSize size,
   }
 
   // If the context has no feature and there are DD properties,
-  // use a clone and clear all DDs: see issue #19096
+  // use a clone and clear some DDs: see issue #19096
   // Applying a data defined size to a categorized layer hides its category symbol in the layers panel and legend
   if ( symbol->hasDataDefinedProperties() &&
        !( customContext
@@ -682,7 +682,13 @@ QPixmap QgsSymbolLayerUtils::symbolPreviewPixmap( QgsSymbol *symbol, QSize size,
     const QgsSymbolLayerList layers( symbol_noDD->symbolLayers() );
     for ( const auto &layer : layers )
     {
-      layer->dataDefinedProperties().clear();
+      for ( int i = 0; i < layer->dataDefinedProperties().count(); ++i )
+      {
+        QgsProperty &prop = layer->dataDefinedProperties().property( i );
+        // don't clear project color properties -- we want to show them in symbol previews
+        if ( prop.isActive() && !prop.isProjectColor() )
+          prop.setActive( false );
+      }
     }
     symbol_noDD->drawPreviewIcon( &painter, size, customContext );
   }