Feature #8725: Fix dpi bug

Author: ahuarte47

src/core/qgsvectorlayer.cpp

@@ -696,10 +696,13 @@ bool QgsVectorLayer::draw( QgsRenderContext& rendererContext )
   // Enable the simplification of the geometries before fetch the features using the current map2pixel context.
   if ( mSimplifyDrawing && !(featureRequest.flags() & QgsFeatureRequest::NoGeometry) )
   {
+    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 );
+    featureRequest.setMapToPixelTol( mSimplifyDrawingTol * 72.0f/dpi );
   }
 
   QgsFeatureIterator fit = getFeatures( featureRequest );

src/providers/ogr/qgsogrfeatureiterator.cpp

@@ -345,6 +345,9 @@ bool QgsOgrSimplifiedFeatureIterator::simplifyOgrGeometry( const QgsFeatureReque
   {
     OGRLineString* lineString = (OGRLineString*)geometry;
 
+    int numPoints = lineString->getNumPoints();
+    if ( (isaLinearRing && numPoints<=5) || (!isaLinearRing && numPoints<=2) ) return false;
+
     OGREnvelope env;
     geometry->getEnvelope(&env );
     QgsRectangle envelope( env.MinX, env.MinY, env.MaxX, env.MaxY );
@@ -384,8 +387,6 @@ bool QgsOgrSimplifiedFeatureIterator::simplifyOgrGeometry( const QgsFeatureReque
     else
     {
       QGis::GeometryType geometryType = isaLinearRing ? QGis::Polygon : QGis::Line;
-
-      int numPoints = lineString->getNumPoints();
       int numSimplifiedPoints = 0;
 
       OGRRawPoint* points = mallocPoints( numPoints );