Restore BBoxCache usage for zone fill performance.

libs/kimath/include/geometry/shape.h

@@ -308,6 +308,8 @@ public:
     virtual size_t         GetPointCount() const          = 0;
     virtual size_t         GetSegmentCount() const        = 0;
     virtual bool IsClosed() const = 0;
+
+    virtual BOX2I* GetCachedBBox() const { return nullptr; }
 };
 
 #endif // __SHAPE_H

libs/kimath/include/geometry/shape_line_chain.h

@@ -413,9 +413,9 @@ public:
             m_bbox.Inflate( m_width );
     }
 
-    const BOX2I BBoxFromCache() const
+    BOX2I* GetCachedBBox() const override
     {
-        return m_bbox;
+        return &m_bbox;
     }
 
     /**

libs/kimath/src/geometry/shape_line_chain.cpp

@@ -1323,10 +1323,8 @@ bool SHAPE_LINE_CHAIN_BASE::PointInside( const VECTOR2I& aPt, int aAccuracy,
      * Don't check the bounding box unless it's cached.  Building it is about the same speed as
      * the rigorous test below and so just slows things down by doing potentially two tests.
      */
-    //if( aUseBBoxCache && !m_bbox.Contains( aPt ) )
-        //return false;
-
-    // fixme: bbox cache...
+    if( aUseBBoxCache && GetCachedBBox() && !GetCachedBBox()->Contains( aPt ) )
+        return false;
 
     if( !IsClosed() || GetPointCount() < 3 )
         return false;

libs/kimath/src/geometry/shape_poly_set.cpp

@@ -1402,9 +1402,9 @@ const BOX2I SHAPE_POLY_SET::BBoxFromCaches() const
     for( unsigned i = 0; i < m_polys.size(); i++ )
     {
         if( i == 0 )
-            bb = m_polys[i][0].BBoxFromCache();
+            bb = *m_polys[i][0].GetCachedBBox();
         else
-            bb.Merge( m_polys[i][0].BBoxFromCache() );
+            bb.Merge( *m_polys[i][0].GetCachedBBox() );
     }
 
     return bb;