Fixing issue #2208

Problem was rounding that lead to incorrect distance measurements
between parallel edges when one edge was very short.

src/db/db/dbEdge.h

@@ -858,7 +858,7 @@ public:
   coord_type distance (const db::point<C> &p) const
   {
     //  the distance is computed from 
-    //    d = (a x b) / sqrt (a * a)
+    //    d = (a x b) / |a|
     //  where b = p - p1, a = p2 - p1
     if (is_degenerate ()) {
       //  for safety handle this case - without a reasonable result
@@ -866,7 +866,7 @@ public:
     } else {
       //  compute the distance as described above 
       area_type axb = coord_traits::vprod (m_p2.x (), m_p2.y (), p.x (), p.y (), m_p1.x (), m_p1.y ()); 
-      double d = double (axb) / double (length ());
+      double d = double (axb) / double_length ();
       //  and round
       return coord_traits::rounded (d);
     }
@@ -929,7 +929,7 @@ public:
   distance_type distance_abs (const db::point<C> &p) const
   {
     //  the distance is computed from 
-    //    d = (a x b) / sqrt (a * a)
+    //    d = (a x b) / |a|
     //  where b = p - p1, a = p2 - p1
     if (is_degenerate ()) {
       //  for safety handle this case - without a reasonable result
@@ -937,7 +937,7 @@ public:
     } else {
       //  compute the distance as described above 
       area_type axb = coord_traits::vprod (m_p2.x (), m_p2.y (), p.x (), p.y (), m_p1.x (), m_p1.y ()); 
-      double d = fabs (double (axb)) / double (length ());
+      double d = fabs (double (axb)) / double_length ();
       //  and round
       return coord_traits::rounded_distance (d);
     }

src/db/unit_tests/dbPolygonToolsTests.cc

@@ -1327,7 +1327,7 @@ TEST(105)
   EXPECT_EQ (smooth (p, 0, false).to_string (),  "(0,0;0,1000;100,1000;100,1100;800,1100;800,1000;2000,1000;2000,0)");
   EXPECT_EQ (smooth (p, 50, false).to_string (),  "(0,0;0,1000;100,1000;100,1100;800,1100;800,1000;2000,1000;2000,0)");
   EXPECT_EQ (smooth (p, 80, false).to_string (),  "(0,0;0,1000;100,1100;800,1100;800,1000;2000,1000;2000,0)");
-  EXPECT_EQ (smooth (p, 90, false).to_string (),  "(0,0;100,1100;800,1100;800,1000;2000,1000;2000,0)");
+  EXPECT_EQ (smooth (p, 90, false).to_string (),  "(0,0;0,1000;800,1100;800,1000;2000,1000;2000,0)");
   EXPECT_EQ (smooth (p, 100, false).to_string (),  "(0,0;0,1000;2000,1000;2000,0)");
   EXPECT_EQ (smooth (p, 100, true).to_string (),  "(0,0;0,1000;100,1000;100,1100;800,1100;800,1000;2000,1000;2000,0)");
 }

src/db/unit_tests/dbRegionTests.cc

@@ -2998,3 +2998,24 @@ TEST(issue_909)
   EXPECT_EQ (r.to_string (), "(0,0;0,100;100,100;100,0);(0,0;0,300;200,300;200,0)");
 }
 
+TEST(issue_2208)
+{
+  db::Point points[] = {
+    db::Point (-36, -2698),
+    db::Point (-3226, 492),
+    db::Point (-2871, 847),
+    db::Point (-746, -1278),
+    db::Point (-751, -1283),
+    db::Point (-746, -1288),
+    db::Point (-741, -1283),
+    db::Point (319, -2343)
+  };
+
+  db::Region r;
+  db::Polygon p;
+  p.assign_hull (points + 0, points + sizeof (points) / sizeof (points [0]));
+  r.insert (p);
+
+  db::EdgePairs ep = r.width_check (500);
+  EXPECT_EQ (ep.to_string (), "(-1046,-1688;-1151,-1583)|(-751,-1283;-746,-1288)");
+}