Fix #11006 (wrong size of symbols in print composer legend if map units are used)

python/core/qgslegendsettings.sip

@@ -71,6 +71,12 @@ class QgsLegendSettings
     bool useAdvancedEffects() const;
     void setUseAdvancedEffects( bool use );
 
+    double mapScale() const;
+    void setMapScale( double scale );
+
+    int dpi() const;
+    void setDpi( int dpi );
+
     // utility functions
 
     /** Splits a string using the wrap char taking into account handling empty

python/core/symbology-ng/qgssymbolv2.sip

@@ -80,7 +80,10 @@ class QgsSymbolV2
     void setColor( const QColor& color );
     QColor color() const;
 
-    void drawPreviewIcon( QPainter* painter, QSize size );
+    //! Draw icon of the symbol that occupyies area given by size using the painter.
+    //! Optionally custom context may be given in order to get rendering of symbols that use map units right.
+    //! @note customContext parameter added in 2.6
+    void drawPreviewIcon( QPainter* painter, QSize size, QgsRenderContext* customContext = 0 );
 
     QImage bigSymbolPreviewImage();
 

src/core/composer/qgscomposerlegend.cpp

@@ -65,7 +65,11 @@ void QgsComposerLegend::paint( QPainter* painter, const QStyleOptionGraphicsItem
 
 
   if ( mComposition )
+  {
     mSettings.setUseAdvancedEffects( mComposition->useAdvancedEffects() );
+    mSettings.setMapScale( mComposition->mapSettings().scale() );
+    mSettings.setDpi( painter->device()->logicalDpiX() );
+  }
   if ( mComposerMap )
     mSettings.setMmPerMapUnit( mComposerMap->mapUnitsToMM() );
 

src/core/layertree/qgslayertreemodellegendnode.cpp

@@ -207,9 +207,13 @@ QSizeF QgsSymbolV2LegendNode::drawSymbol( const QgsLegendSettings& settings, Ite
     return QSizeF();
   }
 
-  //consider relation to composer map for symbol sizes in mm
+  // setup temporary render context
-  bool sizeInMapUnits = s->outputUnit() == QgsSymbolV2::MapUnit;
+  QgsRenderContext context;
-  QgsMarkerSymbolV2* markerSymbol = dynamic_cast<QgsMarkerSymbolV2*>( s );
+  context.setScaleFactor( settings.dpi() / 25.4 );
+  context.setRendererScale( settings.mapScale() );
+  context.setMapToPixel( QgsMapToPixel( 1 / ( settings.mmPerMapUnit() * context.scaleFactor() ) ) ); // hope it's ok to leave out other params
+  context.setForceVectorOutput( true );
+  context.setPainter( ctx ? ctx->painter : 0 );
 
   //Consider symbol size for point markers
   double height = settings.symbolSize().height();
@@ -219,17 +223,12 @@ QSizeF QgsSymbolV2LegendNode::drawSymbol( const QgsLegendSettings& settings, Ite
   double widthOffset = 0;
   double heightOffset = 0;
 
-  if ( markerSymbol )
+  if ( QgsMarkerSymbolV2* markerSymbol = dynamic_cast<QgsMarkerSymbolV2*>( s ) )
   {
-    size = markerSymbol->size();
+    // allow marker symbol to occupy bigger area if necessary
+    size = markerSymbol->size() * QgsSymbolLayerV2Utils::lineWidthScaleFactor( context, s->outputUnit(), s->mapUnitScale() ) / context.scaleFactor();
     height = size;
     width = size;
-    if ( sizeInMapUnits )
-    {
-      height *= settings.mmPerMapUnit();
-      width *= settings.mmPerMapUnit();
-      markerSymbol->setSize( width );
-    }
     if ( width < settings.symbolSize().width() )
     {
       widthOffset = ( settings.symbolSize().width() - width ) / 2.0;
@@ -247,18 +246,7 @@ QSizeF QgsSymbolV2LegendNode::drawSymbol( const QgsLegendSettings& settings, Ite
     QPainter* p = ctx->painter;
 
     //setup painter scaling to dots so that raster symbology is drawn to scale
-    double dotsPerMM = 1.0;
+    double dotsPerMM = context.scaleFactor();
-    QPaintDevice* paintDevice = p->device();
-    if ( !paintDevice )
-    {
-      return QSizeF();
-    }
-    dotsPerMM = paintDevice->logicalDpiX() / 25.4;
-
-    if ( markerSymbol && sizeInMapUnits )
-    {
-      s->setOutputUnit( QgsSymbolV2::MM );
-    }
 
     int opacity = 255;
     if ( QgsVectorLayer* vectorLayer = dynamic_cast<QgsVectorLayer*>( parent()->layer() ) )
@@ -275,7 +263,7 @@ QSizeF QgsSymbolV2LegendNode::drawSymbol( const QgsLegendSettings& settings, Ite
       tempImage.fill( Qt::transparent );
       imagePainter.translate( dotsPerMM * ( currentXPosition + widthOffset ),
                               dotsPerMM * ( currentYCoord + heightOffset ) );
-      s->drawPreviewIcon( &imagePainter, QSize( width * dotsPerMM, height * dotsPerMM ) );
+      s->drawPreviewIcon( &imagePainter, QSize( width * dotsPerMM, height * dotsPerMM ), &context );
       //reduce opacity of image
       imagePainter.setCompositionMode( QPainter::CompositionMode_DestinationIn );
       imagePainter.fillRect( tempImage.rect(), QColor( 0, 0, 0, opacity ) );
@@ -287,15 +275,9 @@ QSizeF QgsSymbolV2LegendNode::drawSymbol( const QgsLegendSettings& settings, Ite
     {
       p->translate( currentXPosition + widthOffset, currentYCoord + heightOffset );
       p->scale( 1.0 / dotsPerMM, 1.0 / dotsPerMM );
-      s->drawPreviewIcon( p, QSize( width * dotsPerMM, height * dotsPerMM ) );
+      s->drawPreviewIcon( p, QSize( width * dotsPerMM, height * dotsPerMM ), &context );
     }
     p->restore();
-
-    if ( markerSymbol && sizeInMapUnits )
-    {
-      s->setOutputUnit( QgsSymbolV2::MapUnit );
-      markerSymbol->setSize( size );
-    }
   }
 
   return QSizeF( qMax( width + 2 * widthOffset, settings.symbolSize().width() ),

src/core/qgslegendsettings.cpp

@@ -32,6 +32,8 @@ QgsLegendSettings::QgsLegendSettings()
     , mEqualColumnWidth( false )
     , mMmPerMapUnit( 1 )
     , mUseAdvancedEffects( true )
+    , mMapScale( 1 )
+    , mDpi( 96 ) // based on QImage's default DPI
 {
   rstyle( QgsComposerLegendStyle::Title ).setMargin( QgsComposerLegendStyle::Bottom, 2 );
   rstyle( QgsComposerLegendStyle::Group ).setMargin( QgsComposerLegendStyle::Top, 2 );

src/core/qgslegendsettings.h

@@ -94,6 +94,12 @@ class CORE_EXPORT QgsLegendSettings
     bool useAdvancedEffects() const { return mUseAdvancedEffects; }
     void setUseAdvancedEffects( bool use ) { mUseAdvancedEffects = use; }
 
+    double mapScale() const { return mMapScale; }
+    void setMapScale( double scale ) { mMapScale = scale; }
+
+    int dpi() const { return mDpi; }
+    void setDpi( int dpi ) { mDpi = dpi; }
+
     // utility functions
 
     /** Splits a string using the wrap char taking into account handling empty
@@ -175,6 +181,12 @@ class CORE_EXPORT QgsLegendSettings
 
     /** Whether to use advanced effects like transparency for symbols - may require their rasterization */
     bool mUseAdvancedEffects;
+
+    /** Denominator of map's scale */
+    double mMapScale;
+
+    /** DPI to be used when rendering legend */
+    int mDpi;
 };
 
 

src/core/symbology-ng/qgssymbolv2.cpp

@@ -283,9 +283,9 @@ QColor QgsSymbolV2::color() const
   return QColor( 0, 0, 0 );
 }
 
-void QgsSymbolV2::drawPreviewIcon( QPainter* painter, QSize size )
+void QgsSymbolV2::drawPreviewIcon( QPainter* painter, QSize size, QgsRenderContext* customContext )
 {
-  QgsRenderContext context = QgsSymbolLayerV2Utils::createRenderContext( painter );
+  QgsRenderContext context = customContext ? *customContext : QgsSymbolLayerV2Utils::createRenderContext( painter );
   context.setForceVectorOutput( true );
   QgsSymbolV2RenderContext symbolContext( context, outputUnit(), mAlpha, false, mRenderHints, 0, 0, mapUnitScale() );
 

src/core/symbology-ng/qgssymbolv2.h

@@ -105,7 +105,10 @@ class CORE_EXPORT QgsSymbolV2
     void setColor( const QColor& color );
     QColor color() const;
 
-    void drawPreviewIcon( QPainter* painter, QSize size );
+    //! Draw icon of the symbol that occupyies area given by size using the painter.
+    //! Optionally custom context may be given in order to get rendering of symbols that use map units right.
+    //! @note customContext parameter added in 2.6
+    void drawPreviewIcon( QPainter* painter, QSize size, QgsRenderContext* customContext = 0 );
 
     QImage bigSymbolPreviewImage();