geometry: SHAPE_LINE_CHAIN::PathLength() now can accept the maximum index of the segment to calculate the length to

libs/kimath/include/geometry/shape_line_chain.h

@@ -610,7 +610,7 @@ public:
      * belonging to our line.
      * @return: path length in Euclidean metric or -1 if aP does not belong to the line chain.
      */
-    int PathLength( const VECTOR2I& aP ) const;
+    int PathLength( const VECTOR2I& aP, int aIndex = -1 ) const;
 
     /**
      * Function CheckClearance()

libs/kimath/src/geometry/shape_line_chain.cpp

@@ -842,7 +842,7 @@ int SHAPE_LINE_CHAIN::Intersect( const SHAPE_LINE_CHAIN& aChain, INTERSECTIONS&
 }
 
 
-int SHAPE_LINE_CHAIN::PathLength( const VECTOR2I& aP ) const
+int SHAPE_LINE_CHAIN::PathLength( const VECTOR2I& aP, int aIndex ) const
 {
     int sum = 0;
 
@@ -851,7 +851,21 @@ int SHAPE_LINE_CHAIN::PathLength( const VECTOR2I& aP ) const
         const SEG seg = CSegment( i );
         int d = seg.Distance( aP );
 
-        if( d <= 1 )
+        bool indexMatch = true;
+
+        if( aIndex >= 0 )
+        {
+            if( aIndex == SegmentCount() )
+            {
+                indexMatch = ( i == SegmentCount() - 1 );
+            }
+            else
+            {
+                indexMatch = ( i == aIndex );
+            }
+        }
+
+        if( indexMatch )
         {
             sum += ( aP - seg.A ).EuclideanNorm();
             return sum;