Some adjustments:

* Fixed instance marker when the cell is made from empty ones only
* 'fit' will include empty instances

src/db/db/dbInstances.cc

@@ -907,6 +907,19 @@ Instance::bbox () const
   }
 }
 
+Instance::box_type
+Instance::bbox_with_empty () const
+{
+  const db::Instances *i = instances ();
+  const db::Cell *c = i ? i->cell () : 0;
+  const db::Layout *g = c ? c->layout () : 0;
+  if (g) {
+    return bbox (db::box_convert<cell_inst_type, false> (*g));
+  } else {
+    return db::Instance::box_type ();
+  }
+}
+
 // -------------------------------------------------------------------------------------
 //  Instances implementation
 

src/db/db/dbInstances.h

@@ -338,6 +338,15 @@ public:
    */
   cell_inst_array_type::box_type bbox () const;
 
+  /**
+   *  @brief Returns the bounding box of this array, including empty instances
+   *
+   *  This method uses the pointers provided internally to identify container and cell.
+   *  In constrast to normal "bbox", this bounding box considers empty cells as
+   *  point-like with a box of (0,0;0,0).
+   */
+  cell_inst_array_type::box_type bbox_with_empty () const;
+
   /**
    *  @brief Return the iterator for the instances of the array
    *

src/db/unit_tests/dbCellTests.cc

@@ -723,6 +723,7 @@ TEST(3a)
   EXPECT_EQ (inst.to_string (), "cell_index=1 r0 100,-100");
   EXPECT_EQ (inst.bbox ().to_string (), "()");
   EXPECT_EQ (inst.bbox (db::box_convert<db::CellInst, false> (g)).to_string (), "(100,-100;100,-100)");
+  EXPECT_EQ (inst.bbox_with_empty ().to_string (), "(100,-100;100,-100)");
   EXPECT_EQ (c0.bbox ().to_string (), "()");
   EXPECT_EQ (c0.bbox_with_empty ().to_string (), "(100,-100;100,-100)");
 

src/laybasic/laybasic/layLayerProperties.cc

@@ -790,7 +790,29 @@ LayerPropertiesNode::set_parent (const LayerPropertiesNode *parent)
   mp_parent.reset (const_cast<LayerPropertiesNode *>(parent));
 }
 
-db::DBox 
+db::DBox
+LayerPropertiesNode::overall_bbox () const
+{
+  tl_assert (mp_view);
+  lay::CellView cv = mp_view->cellview (cellview_index ());
+
+  if (! cv.is_valid ()) {
+
+    return db::DBox ();
+
+  } else {
+
+    db::DBox b;
+    double dbu = cv->layout ().dbu ();
+    for (std::vector<db::DCplxTrans>::const_iterator t = trans ().begin (); t != trans ().end (); ++t) {
+      b += (*t * db::CplxTrans (dbu) * cv.context_trans ()) * cv.cell ()->bbox_with_empty ();
+    }
+    return b;
+
+  }
+}
+
+db::DBox
 LayerPropertiesNode::bbox () const
 {
   tl_assert (mp_view);
@@ -802,12 +824,7 @@ LayerPropertiesNode::bbox () const
 
   } else if (is_cell_box_layer ()) {
 
-    db::DBox b;
-    double dbu = cv->layout ().dbu ();
-    for (std::vector<db::DCplxTrans>::const_iterator t = trans ().begin (); t != trans ().end (); ++t) {
-      b += (*t * db::CplxTrans (dbu) * cv.context_trans ()) * cv.cell ()->bbox ();
-    }
-    return b;
+    return overall_bbox ();
 
   } else {
 

src/laybasic/laybasic/layLayerProperties.h

@@ -1182,7 +1182,17 @@ public:
    *  @return A bbox in micron units
    */
   db::DBox bbox () const;
-  
+
+  /**
+   *  @brief Computes the overall box of this layer
+   *
+   *  This is not a layer specific box, but an all-layer box,
+   *  including transformations (if specified).
+   *  This box is equivalent to the box delivered by
+   *  a cell frame layer.
+   */
+  db::DBox overall_bbox () const;
+
   /**
    *  @brief Attach to a view
    *

src/laybasic/laybasic/layLayoutViewBase.cc

@@ -3865,7 +3865,7 @@ LayoutViewBase::full_box () const
   db::DBox bbox;
 
   for (LayerPropertiesConstIterator l = get_properties ().begin_const_recursive (); ! l.at_end (); ++l) {
-    bbox += l->bbox ();
+    bbox += l->overall_bbox ();
   }
 
   for (lay::AnnotationShapes::iterator a = annotation_shapes ().begin (); ! a.at_end (); ++a) {

src/laybasic/laybasic/layMarker.cc

@@ -53,7 +53,7 @@ void render_cell_inst (const db::Layout &layout, const db::CellInstArray &inst,
 
   const db::Cell &cell = layout.cell (inst.object ().cell_index ());
   std::string cell_name = layout.display_name (inst.object ().cell_index ());
-  db::Box cell_box = cell.bbox ();
+  db::Box cell_box = cell.bbox_with_empty ();
 
   db::Vector a, b;
   unsigned long amax = 0, bmax = 0;
@@ -589,7 +589,12 @@ InstanceMarker::set_max_shapes (size_t s)
 db::DBox
 InstanceMarker::item_bbox () const 
 {
-  return db::DBox (m_inst.bbox ());
+  const db::Layout *ly = layout ();
+  if (! ly) {
+    return db::DBox ();
+  }
+
+  return db::DBox (m_inst.bbox_with_empty ());
 }
 
 // ------------------------------------------------------------------------
@@ -1059,7 +1064,7 @@ Marker::item_bbox () const
   } else if (m_type == Instance) {
     const db::Layout *ly = layout ();
     if (ly) {
-      return db::DBox (m_object.inst->bbox (db::box_convert <db::CellInst> (*ly)));
+      return db::DBox (m_object.inst->bbox (db::box_convert <db::CellInst, false> (*ly)));
     }
   }
   return db::DBox ();

src/laybasic/laybasic/layRedrawThreadWorker.cc

@@ -631,7 +631,7 @@ RedrawThreadWorker::draw_cell (bool drawing_context, int level, const db::CplxTr
   lay::CanvasPlane *vertices = m_planes[3 + plane_group * (planes_per_layer / 3)];
 
   if (empty_cell) {
-    r.draw (dbox, 0, 0, vertices, 0);
+    r.draw (dbox, 0, contour, vertices, 0);
   } else {
     r.draw (dbox, fill, contour, 0, 0);
   }