Feature #8725: Disable simplification in composer

Disable the simplification of geometries when the render request comes
from a print composition to avoid rendering quality issues

Author: ahuarte47

src/core/composer/qgscomposermap.cpp

@@ -191,13 +191,14 @@ void QgsComposerMap::draw( QPainter *painter, const QgsRectangle& extent, const
   {
     theRendererContext->setDrawEditingInformation( false );
     theRendererContext->setRenderingStopped( false );
-  }
+    theRendererContext->setRenderingPrintComposition( true );
 
-  // force vector output (no caching of marker images etc.)
-  theRendererContext->setForceVectorOutput( true );
+    // force vector output (no caching of marker images etc.)
+    theRendererContext->setForceVectorOutput( true );
 
-  // make the renderer respect the composition's useAdvancedEffects flag
-  theRendererContext->setUseAdvancedEffects( mComposition->useAdvancedEffects() );
+    // make the renderer respect the composition's useAdvancedEffects flag
+    theRendererContext->setUseAdvancedEffects( mComposition->useAdvancedEffects() );
+  }
 
   //force composer map scale for scale dependent visibility
   double bk_scale = theMapRenderer.scale();

src/core/qgsrendercontext.cpp

@@ -28,7 +28,8 @@ QgsRenderContext::QgsRenderContext()
     mScaleFactor( 1.0 ),
     mRasterScaleFactor( 1.0 ),
     mRendererScale( 1.0 ),
-    mLabelingEngine( NULL )
+    mLabelingEngine( NULL ),
+    mRenderingPrintComposition( false )
 {
 
 }

src/core/qgsrendercontext.h

@@ -95,6 +95,10 @@ class CORE_EXPORT QgsRenderContext
     //! Added in QGIS v2.0
     void setSelectionColor( const QColor& color ) { mSelectionColor = color; }
 
+    /**True if the rendering request comes from a print composition, false it comes from a normal window request */
+    void setRenderingPrintComposition( bool renderingPrintComposition ) { mRenderingPrintComposition = renderingPrintComposition; }
+    bool renderingPrintComposition( ) const { return mRenderingPrintComposition; }
+
   private:
 
     /**Painter for rendering operations*/
@@ -133,6 +137,9 @@ class CORE_EXPORT QgsRenderContext
 
     /** Color used for features that are marked as selected */
     QColor mSelectionColor;
+
+    /**True if the rendering request comes from a print composition, false it comes from a normal window request */
+    bool mRenderingPrintComposition;
 };
 
 #endif

src/core/qgsvectorlayer.cpp

@@ -694,15 +694,15 @@ bool QgsVectorLayer::draw( QgsRenderContext& rendererContext )
                                      .setSubsetOfAttributes( attributes );
 
   // Enable the simplification of the geometries before fetch the features using the current map2pixel context.
-  if ( simplifyDrawingCanbeApplied() && !(featureRequest.flags() & QgsFeatureRequest::NoGeometry) )
+  if ( simplifyDrawingCanbeApplied() && !(featureRequest.flags() & QgsFeatureRequest::NoGeometry) && !rendererContext.renderingPrintComposition() )
   {
     QPainter* p = rendererContext.painter();
     float dpi = ( p->device()->logicalDpiX() + p->device()->logicalDpiY() ) / 2;
 
     featureRequest.setFlags( featureRequest.flags() | QgsFeatureRequest::SimplifyGeometries );
     featureRequest.setCoordinateTransform( rendererContext.coordinateTransform() );
     featureRequest.setMapToPixel( &rendererContext.mapToPixel() );
-    featureRequest.setMapToPixelTol( mSimplifyDrawingTol * 72.0f/dpi );
+    featureRequest.setMapToPixelTol( mSimplifyDrawingTol * 96.0f/dpi );
   }
 
   QgsFeatureIterator fit = getFeatures( featureRequest );

src/core/qgsvectorlayer.h

@@ -1373,7 +1373,7 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     bool simplifyDrawing() const { return mSimplifyDrawing; }
 
     /** Returns whether the VectorLayer can apply geometry simplification in FeatureRequests */
-    bool simplifyDrawingCanbeApplied() const { return mSimplifyDrawing && !mEditBuffer; }
+    bool simplifyDrawingCanbeApplied() const { return mSimplifyDrawing && !mEditBuffer && ( !mCurrentRendererContext || !mCurrentRendererContext->renderingPrintComposition() ); }
 
   public slots:
     /**