Consider rotation in rubberband placement

Fixes artifacts on zoom by rectangle (#11910) and placement of
measure tool rubberband.

src/gui/qgsrubberband.cpp

@@ -425,13 +425,15 @@ void QgsRubberBand::setToCanvasRectangle( const QRect& rect )
 
   const QgsMapToPixel* transform = mMapCanvas->getCoordinateTransform();
   QgsPoint ll = transform->toMapCoordinates( rect.left(), rect.bottom() );
+  QgsPoint lr = transform->toMapCoordinates( rect.right(), rect.bottom() );
+  QgsPoint ul = transform->toMapCoordinates( rect.left(), rect.top() );
   QgsPoint ur = transform->toMapCoordinates( rect.right(), rect.top() );
 
   reset( QGis::Polygon );
   addPoint( ll, false );
-  addPoint( QgsPoint( ur.x(), ll.y() ), false );
+  addPoint( lr, false );
   addPoint( ur, false );
-  addPoint( QgsPoint( ll.x(), ur.y() ), true );
+  addPoint( ul, true );
 }
 
 /*!
@@ -518,39 +520,45 @@ void QgsRubberBand::paint( QPainter* p )
 
 void QgsRubberBand::updateRect()
 {
-  if ( mPoints.size() > 0 )
+  if ( mPoints.empty() )
   {
-    //initial point
-    QList<QgsPoint>::const_iterator it = mPoints.at( 0 ).constBegin();
-    if ( it == mPoints.at( 0 ).constEnd() )
-    {
-      return;
-    }
+    setRect( QgsRectangle() );
+    setVisible( false );
+    return;
+  }
 
-    qreal scale = mMapCanvas->mapUnitsPerPixel();
-    qreal s = ( mIconSize - 1 ) / 2 * scale;
-    qreal p = mPen.width() * scale;
+  const QgsMapToPixel& m2p = *( mMapCanvas->getCoordinateTransform() );
 
-    QgsRectangle r( it->x() + mTranslationOffsetX - s - p, it->y() + mTranslationOffsetY - s - p,
-                    it->x() + mTranslationOffsetX + s + p, it->y() + mTranslationOffsetY + s + p );
+  qreal w = ( mIconSize - 1 ) / 2 + mPen.width();
 
-    for ( int i = 0; i < mPoints.size(); ++i )
+  QgsRectangle r;
+  for ( int i = 0; i < mPoints.size(); ++i )
+  {
+    QList<QgsPoint>::const_iterator it = mPoints.at( i ).constBegin(),
+                                         itE = mPoints.at( i ).constEnd();
+    int j = 0;
+    for ( ; it != itE; ++it )
     {
-      QList<QgsPoint>::const_iterator it = mPoints.at( i ).constBegin();
-      for ( ; it != mPoints.at( i ).constEnd(); ++it )
-      {
-        QgsRectangle rect = QgsRectangle( it->x() + mTranslationOffsetX - s - p, it->y() + mTranslationOffsetY - s - p,
-                                          it->x() + mTranslationOffsetX + s + p, it->y() + mTranslationOffsetY + s + p );
-        r.combineExtentWith( &rect );
-      }
+      QgsPoint p( it->x() + mTranslationOffsetX, it->y() + mTranslationOffsetY );
+      p = m2p.transform( p );
+      QgsRectangle rect( p.x() - w, p.y() - w, p.x() + w, p.y() + w );
+      r.combineExtentWith( &rect );
     }
-    setRect( r );
   }
-  else
-  {
-    setRect( QgsRectangle() );
-  }
-  setVisible( mPoints.size() > 0 );
+
+  // This is an hack to pass QgsMapCanvasItem::setRect what it
+  // expects (encoding of position and size of the item)
+  QgsPoint topLeft = m2p.toMapPoint( r.xMinimum(), r.yMinimum() );
+  double res = m2p.mapUnitsPerPixel();
+  QgsRectangle rect( topLeft.x(), topLeft.y(), topLeft.x() + r.width()*res, topLeft.y() - r.height()*res );
+
+  setRect( rect );
+  setVisible( true );
+}
+
+void QgsRubberBand::updatePosition( )
+{
+  // nothing to do here...
 }
 
 void QgsRubberBand::setTranslationOffset( double dx, double dy )

src/gui/qgsrubberband.h

@@ -242,6 +242,8 @@ class GUI_EXPORT QgsRubberBand: public QgsMapCanvasItem
      */
     QgsGeometry* asGeometry();
 
+    virtual void updatePosition();
+
   protected:
     virtual void paint( QPainter* p );