Further drop now-unused code added with map rotation support

Also add some documenting comments

src/gui/qgsmapcanvasitem.cpp

@@ -67,21 +67,6 @@ QPointF QgsMapCanvasItem::toCanvasCoordinates( const QgsPoint& point )
   return QPointF( x, y ) + mPanningOffset;
 }
 
-// private
-QRectF QgsMapCanvasItem::toCanvasCoordinates( const QRectF& rect )
-{
-  QPointF tl( toCanvasCoordinates( rect.topLeft() ) );
-  QPointF bl( toCanvasCoordinates( rect.bottomLeft() ) );
-  QPointF br( toCanvasCoordinates( rect.bottomRight() ) );
-  QPointF tr( toCanvasCoordinates( rect.topRight() ) );
-  double xmin = std::min( tl.x(), std::min( bl.x(), std::min( br.x(), tr.x() ) ) );
-  double ymin = std::min( tl.y(), std::min( bl.y(), std::min( br.y(), tr.y() ) ) );
-  double xmax = std::max( tl.x(), std::max( bl.x(), std::max( br.x(), tr.x() ) ) );
-  double ymax = std::max( tl.y(), std::max( bl.y(), std::max( br.y(), tr.y() ) ) );
-  return QRectF( QPointF( xmin, ymin ), QPointF( xmax, ymax ) );
-}
-
-
 QgsRectangle QgsMapCanvasItem::rect() const
 {
   return mRect;

src/gui/qgsmapcanvasitem.h

@@ -82,23 +82,24 @@ class GUI_EXPORT QgsMapCanvasItem : public QGraphicsItem
     //! pointer to map canvas
     QgsMapCanvas* mMapCanvas;
 
-    //! canvas item rectangle (in map coordinates)
+    //! cached canvas item rectangle in map coordinates
+    //! encodes position (xmin,ymax) and size (width/height)
+    //! used to re-position and re-size the item on zoom/pan
+    //! while waiting for the renderer to complete.
+    //!
+    //! NOTE: does not include rotation information, so cannot
+    //!       be used to correctly present pre-rendered map
+    //!       on rotation change
     QgsRectangle mRect;
 
     //! offset from normal position due current panning operation,
     //! used when converting map coordinates to move map canvas items
+    //! @deprecated since v2.4
     QPoint mPanningOffset;
 
     //! cached size of the item (to return in boundingRect())
     QSizeF mItemSize;
 
-  private:
-
-    //! transformation from map coordinates to screen coordinates
-    //! if rotation is set it is taken in consideration so that
-    //! the returned rectangle is the bounding box of the rotated input
-    QRectF toCanvasCoordinates( const QRectF& rect );
-
 };
 
 

src/gui/qgsmapcanvasmap.cpp

@@ -50,6 +50,8 @@ void QgsMapCanvasMap::paint( QPainter* painter )
   if ( mImage.size() != QSize( w, h ) )
   {
     QgsDebugMsg( QString( "map paint DIFFERENT SIZE: img %1,%2  item %3,%4" ).arg( mImage.width() ).arg( mImage.height() ).arg( w ).arg( h ) );
+    // This happens on zoom events when ::paint is called before
+    // the renderer has completed
   }
 
   painter->drawImage( QRect( 0, 0, w, h ), mImage );