From fadaf147c5add875593a8fbf4933e890c0d4ed83 Mon Sep 17 00:00:00 2001
From: "Johan B. C. Engelen" <jbc.engelen@swissonline.ch>
Date: Thu, 24 Oct 2013 16:21:44 +0200
Subject: fix crash bug 1237676

Fixed bugs:
  - https://launchpad.net/bugs/1237676

(bzr r12716)
---
 src/conn-avoid-ref.cpp | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

(limited to 'src/conn-avoid-ref.cpp')

diff --git a/src/conn-avoid-ref.cpp b/src/conn-avoid-ref.cpp
index c0d05e3c4..cb72f65dc 100644
--- a/src/conn-avoid-ref.cpp
+++ b/src/conn-avoid-ref.cpp
@@ -303,23 +303,29 @@ static Avoid::Polygon avoid_item_poly(SPItem const *item)
         Geom::Line parallel_hull_edge;
         parallel_hull_edge.setOrigin(hull_edge.origin()+hull_edge.versor().ccw()*spacing);
         parallel_hull_edge.setVersor(hull_edge.versor());
-        
+
         // determine the intersection point
-        
-        Geom::OptCrossing int_pt = Geom::intersection(parallel_hull_edge, prev_parallel_hull_edge);
-        if (int_pt)
-        {
-            Avoid::Point avoid_pt((parallel_hull_edge.origin()+parallel_hull_edge.versor()*int_pt->ta)[Geom::X],
-                                    (parallel_hull_edge.origin()+parallel_hull_edge.versor()*int_pt->ta)[Geom::Y]);
-            poly.ps.push_back(avoid_pt);
+        try {
+            Geom::OptCrossing int_pt = Geom::intersection(parallel_hull_edge, prev_parallel_hull_edge);
+            if (int_pt)
+            {
+                Avoid::Point avoid_pt((parallel_hull_edge.origin()+parallel_hull_edge.versor()*int_pt->ta)[Geom::X],
+                                        (parallel_hull_edge.origin()+parallel_hull_edge.versor()*int_pt->ta)[Geom::Y]);
+                poly.ps.push_back(avoid_pt);
+            }
+            else
+            {
+                // something went wrong...
+                std::cout<<"conn-avoid-ref.cpp: avoid_item_poly: Geom:intersection failed."<<std::endl;
+            }
         }
-        else
-        {
-            // something went wrong...
-            std::cout<<"conn-avoid-ref.cpp: avoid_item_poly: Geom:intersection failed."<<std::endl;
+        catch (Geom::InfiniteSolutions const &e) {
+            // the parallel_hull_edge and prev_parallel_hull_edge lie on top of each other, hence infinite crossings
+            g_message("conn-avoid-ref.cpp: trying to get crossings of identical lines");
         }
         prev_parallel_hull_edge = parallel_hull_edge;
     }
+
     return poly;
 }
 
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