Remove assert and update ruler units on the fly.

Fixes: lp:1781595
* https://bugs.launchpad.net/kicad/+bug/1781595

include/preview_items/ruler_item.h

@@ -71,10 +71,14 @@ public:
         return wxT( "RULER_ITEM" );
     }
 
-private:
+    void UpdateUserUnits( EDA_UNITS_T aUserUnits )
+    {
+        m_userUnits = aUserUnits;
+    }
 
+private:
     const TWO_POINT_GEOMETRY_MANAGER& m_geomMgr;
-    const EDA_UNITS_T                 m_userUnits;
+    EDA_UNITS_T                       m_userUnits;
 };
 
 } // PREVIEW

pcbnew/pcb_base_edit_frame.cpp

@@ -28,7 +28,7 @@
 #include <gal/graphics_abstraction_layer.h>
 #include <class_board.h>
 #include <view/view.h>
-
+#include <tools/pcb_actions.h>
 
 void PCB_BASE_EDIT_FRAME::SetRotationAngle( int aRotationAngle )
 {
@@ -81,3 +81,13 @@ void PCB_BASE_EDIT_FRAME::SetBoard( BOARD* aBoard )
             m_toolManager->ResetTools( TOOL_BASE::MODEL_RELOAD );
     }
 }
+
+
+void PCB_BASE_EDIT_FRAME::unitsChangeRefresh()
+{
+    PCB_BASE_FRAME::unitsChangeRefresh();    // Update the status bar.
+
+    GetToolManager()->RunAction( PCB_ACTIONS::switchUnits, true );  // Notify tools.
+}
+
+

pcbnew/pcb_base_edit_frame.h

@@ -204,6 +204,8 @@ protected:
      * duplicateItem(BOARD_ITEM*, bool) above
      */
     virtual void duplicateItems( bool aIncrement ) = 0;
+
+    void unitsChangeRefresh() override;
 };
 
 #endif

pcbnew/pcb_base_frame.cpp

@@ -59,6 +59,7 @@
 
 #include <tool/tool_manager.h>
 #include <tool/tool_dispatcher.h>
+#include <tools/pcb_actions.h>
 
 const wxChar PCB_BASE_FRAME::CANVAS_TYPE_KEY[] = wxT( "canvas_type" );
 

pcbnew/pcb_edit_frame.cpp

@@ -975,7 +975,7 @@ void PCB_EDIT_FRAME::OnUpdateLayerAlpha( wxUpdateUIEvent & )
 
 void PCB_EDIT_FRAME::unitsChangeRefresh()
 {
-    PCB_BASE_FRAME::unitsChangeRefresh();    // Update the grid size select box.
+    PCB_BASE_EDIT_FRAME::unitsChangeRefresh();    // Update the grid size select box.
 
     ReCreateAuxiliaryToolbar();
 }

pcbnew/tools/edit_tool.cpp

@@ -1253,6 +1253,14 @@ int EDIT_TOOL::MeasureTool( const TOOL_EVENT& aEvent )
             view.Update( &ruler, KIGFX::GEOMETRY );
         }
 
+        else if( evt->IsAction( &PCB_ACTIONS::switchUnits ) )
+        {
+            ruler.UpdateUserUnits( frame()->GetUserUnits() );
+
+            view.SetVisible( &ruler, true );
+            view.Update( &ruler, KIGFX::GEOMETRY );
+        }
+
         else if( evt->IsClick( BUT_RIGHT ) )
         {
             GetManager()->PassEvent();