PNS_DRAGGER should report its layers.

Also, don't use ViewGetLayers() for visibility checking.  For some
things (like vias) it deals with synthetic layers, not board layers.

Fixes https://gitlab.com/kicad/code/kicad/issues/6328

pcbnew/router/pns_component_dragger.h

@@ -79,11 +79,28 @@ public:
      */
     NODE* CurrentNode() const override;
 
+    /**
+     * Function CurrentNets()
+     *
+     * Returns the net code(s) of currently dragged item(s).
+     * Currently unused for component dragging.
+     */
     const std::vector<int> CurrentNets() const override
     {
         return std::vector<int>();
     }
 
+    /**
+     * Function CurrentLayer()
+     *
+     * Returns the layer of currently dragged item(s).
+     * Currently unused for component dragging.
+     */
+    virtual int CurrentLayer() const override
+    {
+        return UNDEFINED_LAYER;
+    }
+
     /**
      * Function Traces()
      *

pcbnew/router/pns_drag_algo.h

@@ -95,8 +95,20 @@ public:
      */
     virtual NODE* CurrentNode() const = 0;
 
+    /**
+     * Function CurrentNets()
+     *
+     * Returns the net code(s) of currently dragged item(s).
+     */
     virtual const std::vector<int> CurrentNets() const = 0;
 
+    /**
+     * Function CurrentLayer()
+     *
+     * Returns the layer of currently dragged item(s).
+     */
+    virtual int CurrentLayer() const = 0;
+
     /**
      * Function Traces()
      *

pcbnew/router/pns_dragger.h

@@ -83,11 +83,26 @@ public:
      */
     NODE* CurrentNode() const override;
 
+    /**
+     * Function CurrentNets()
+     *
+     * Returns the net code(s) of currently routed track(s).
+     */
     const std::vector<int> CurrentNets() const override
     {
         return std::vector<int>( 1, m_draggedLine.Net() );
     }
 
+    /**
+     * Function CurrentLayer()
+     *
+     * Returns the layer of currently routed track.
+     */
+    int CurrentLayer() const override
+    {
+        return m_draggedLine.Layer();
+    }
+
     /**
      * Function Traces()
      *

pcbnew/router/pns_kicad_iface.cpp

@@ -1129,32 +1129,18 @@ bool PNS_KICAD_IFACE::IsItemVisible( const PNS::ITEM* aItem ) const
     if( !m_view || !aItem->Parent() )
         return true;
 
-    BOARD_ITEM* item = aItem->Parent();
-    bool        isOnVisibleLayer = true;
+    BOARD_ITEM*      item = aItem->Parent();
+    bool             isOnVisibleLayer = true;
+    RENDER_SETTINGS* settings = m_view->GetPainter()->GetSettings();
 
-    if( m_view->GetPainter()->GetSettings()->GetHighContrast() )
-    {
-        int  layers[KIGFX::VIEW::VIEW_MAX_LAYERS];
-        int  layers_count;
-        auto activeLayers = m_view->GetPainter()->GetSettings()->GetHighContrastLayers();
-
-        isOnVisibleLayer = false;
-        item->ViewGetLayers( layers, layers_count );
-
-        for( int i = 0; i < layers_count; ++i )
-        {
-            // Item is on at least one of the active layers
-            if( activeLayers.count( layers[i] ) > 0 )
-            {
-                isOnVisibleLayer = true;
-                break;
-            }
-        }
-    }
+    if( settings->GetHighContrast() )
+        isOnVisibleLayer = item->IsOnLayer( settings->GetPrimaryHighContrastLayer() );
 
     if( m_view->IsVisible( item ) && isOnVisibleLayer
             && item->ViewGetLOD( item->GetLayer(), m_view ) < m_view->GetScale() )
+    {
         return true;
+    }
 
     // Items hidden in the router are not hidden on the board
     if( m_hiddenItems.find( item ) != m_hiddenItems.end() )

pcbnew/router/pns_router.cpp

@@ -521,6 +521,9 @@ int ROUTER::GetCurrentLayer() const
 {
     if( m_placer )
         return m_placer->CurrentLayer();
+    else if( m_dragger )
+        return m_dragger->CurrentLayer();
+
     return -1;
 }