Optimize loop

src/gui/qgshighlight.cpp

@@ -221,32 +221,35 @@ void QgsHighlight::paintLine( QPainter *p, QgsPolylineXY line )
   p->drawPolyline( polygon );
 }
 
-void QgsHighlight::paintPolygon( QPainter *p, QgsPolygonXY polygon )
+void QgsHighlight::paintPolygon( QPainter *p, const QgsPolygonXY &polygon )
 {
   // OddEven fill rule by default
   QPainterPath path;
 
   p->setPen( mPen );
   p->setBrush( mBrush );
 
-  for ( int i = 0; i < polygon.size(); i++ )
+  for ( const auto &sourceRing : polygon )
   {
-    if ( polygon[i].empty() ) continue;
+    if ( sourceRing.empty() )
+      continue;
 
     QPolygonF ring;
-    ring.reserve( polygon[i].size() + 1 );
+    ring.reserve( sourceRing.size() + 1 );
 
-    for ( int j = 0; j < polygon[i].size(); j++ )
+    QPointF lastVertex;
+    for ( const auto &sourceVertex : sourceRing )
     {
       //adding point only if it is more than a pixel apart from the previous one
-      const QPointF cur = toCanvasCoordinates( polygon[i][j] ) - pos();
-      if ( 0 == j || std::abs( ring.back().x() - cur.x() ) > 1 || std::abs( ring.back().y() - cur.y() ) > 1 )
+      const QPointF curVertex = toCanvasCoordinates( sourceVertex ) - pos();
+      if ( std::abs( ring.back().x() - curVertex.x() ) > 1 || std::abs( ring.back().y() - curVertex.y() ) > 1 )
       {
-        ring.push_back( cur );
+        ring.push_back( curVertex );
       }
+      lastVertex = curVertex;
     }
 
-    ring.push_back( ring[ 0 ] );
+    ring.push_back( ring.at( 0 ) );
 
     path.addPolygon( ring );
   }

src/gui/qgshighlight.h

@@ -109,7 +109,7 @@ class GUI_EXPORT QgsHighlight: public QgsMapCanvasItem
     QgsFeatureRenderer *getRenderer( QgsRenderContext &context, const QColor &color, const QColor &fillColor );
     void paintPoint( QPainter *p, const QgsPointXY &point );
     void paintLine( QPainter *p, QgsPolylineXY line );
-    void paintPolygon( QPainter *p, QgsPolygonXY polygon );
+    void paintPolygon( QPainter *p, const QgsPolygonXY &polygon );
 
     QBrush mBrush;
     QPen mPen;