libs/kimath: introducing empty shape object (SHAPE_NULL)

libs/kimath/include/geometry/shape.h

@@ -45,7 +45,8 @@ enum SHAPE_TYPE
     SH_SIMPLE,          ///> simple polygon
     SH_POLY_SET,        ///> set of polygons (with holes, etc.)
     SH_COMPOUND,        ///> compound shape, consisting of multiple simple shapes
-    SH_ARC              ///> circular arc
+    SH_ARC,             ///> circular arc
+    SH_NULL             ///> empty shape (no shape...)
 };
 
 static inline wxString SHAPE_TYPE_asString( SHAPE_TYPE a )
@@ -60,6 +61,7 @@ static inline wxString SHAPE_TYPE_asString( SHAPE_TYPE a )
     case SH_POLY_SET:   return "SH_POLY_SET";
     case SH_COMPOUND:   return "SH_COMPOUND";
     case SH_ARC:        return "SH_ARC";
+    case SH_NULL:       return "SH_NULL";
     }
 
     return wxEmptyString;  // Just to quiet GCC.
@@ -113,6 +115,17 @@ public:
         return NULL;
     };
 
+    /**
+     * Function IsNull()
+     *
+     * Returns true if the shape is a null shape.
+     * @retval true if null :-)
+     */
+    bool IsNull() const
+    {
+        return m_type == SH_NULL;
+    }
+
     /**
      * Function Collide()
      *

libs/kimath/include/geometry/shape_null.h

@@ -0,0 +1,79 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2020 CERN
+ * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#ifndef __SHAPE_NULL_H
+#define __SHAPE_NULL_H
+
+#include <geometry/shape.h>
+#include <math/box2.h>
+#include <math/vector2d.h>
+
+#include <algorithm>
+
+class SHAPE_NULL : public SHAPE
+{
+public:
+    SHAPE_NULL() :
+        SHAPE( SH_NULL )
+    {}
+
+    SHAPE_NULL( const SHAPE_NULL& aOther ) :
+        SHAPE( SH_NULL )
+    {};
+
+    ~SHAPE_NULL()
+    {}
+
+    SHAPE* Clone() const override
+    {
+        return new SHAPE_NULL( *this );
+    }
+
+    SHAPE_NULL& operator=( const SHAPE_NULL& ) = default;
+
+    const BOX2I BBox( int aClearance = 0 ) const override
+    {
+        return BOX2I();
+    }
+
+    bool Collide( const SEG& aSeg, int aClearance = 0, int* aActual = nullptr ) const override
+    {
+        return false;
+    }
+
+    void Move( const VECTOR2I& aVector ) override
+    {
+    }
+
+    void Rotate( double aAngle, const VECTOR2I& aCenter = { 0, 0 } ) override
+    {
+    }
+
+    bool IsSolid() const override
+    {
+        return false;
+    }
+};
+
+#endif