sync QgsRubberBand and QgsMpaCanvasMap antialiasing, this also fixes …

…1px QgsRubberBand shift with x11 rendering engine if rendered without antialiasing

src/gui/qgsmapcanvas.cpp

@@ -82,9 +82,10 @@ QgsMapCanvas::QgsMapCanvas( QWidget * parent, const char *name )
     , mCanvasProperties( new CanvasProperties )
     , mNewSize( QSize() )
     , mPainting( false )
+    , mAntiAliasing( false )
 {
   //disable the update that leads to the resize crash
-  if( viewport() )
+  if ( viewport() )
   {
     viewport()->setAttribute( Qt::WA_PaintOnScreen, true );
   }
@@ -163,6 +164,7 @@ QgsMapCanvas::~QgsMapCanvas()
 
 void QgsMapCanvas::enableAntiAliasing( bool theFlag )
 {
+  mAntiAliasing = theFlag;
   mMap->enableAntiAliasing( theFlag );
   if ( mMapOverview )
     mMapOverview->enableAntiAliasing( theFlag );

src/gui/qgsmapcanvas.h

@@ -244,6 +244,9 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! used to determine if anti-aliasing is enabled or not
     void enableAntiAliasing( bool theFlag );
 
+    //! true if antialising is enabled
+    bool antiAliasingEnabled() const { return mAntiAliasing; }
+
     //! Select which Qt class to render with
     void useImageToRender( bool theFlag );
 
@@ -463,6 +466,8 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! currently in paint event
     bool mPainting;
 
+    //! indicates whether antialiasing will be used for rendering
+    bool mAntiAliasing;
 }; // class QgsMapCanvas
 
 

src/gui/qgsmapcanvasitem.cpp

@@ -42,6 +42,10 @@ void QgsMapCanvasItem::paint( QPainter * painter,
                               const QStyleOptionGraphicsItem * option,
                               QWidget * widget )
 {
+  if ( mMapCanvas->antiAliasingEnabled() )
+  {
+    painter->setRenderHint( QPainter::Antialiasing );
+  }
   paint( painter ); // call the derived item's drawing routines
 }