From bc1e5f7a6c42a0fc44adb6f4c41aece472b394ab Mon Sep 17 00:00:00 2001
From: Shaunak Kishore <kshaunak@gmail.com>
Date: Thu, 10 Sep 2015 01:48:04 -0400
Subject: [PATCH] Add bridge intersection points to stroke outline

---
 lib/stroke_extractor.js | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/lib/stroke_extractor.js b/lib/stroke_extractor.js
index 9b0a48d5..6c1c4d89 100644
--- a/lib/stroke_extractor.js
+++ b/lib/stroke_extractor.js
@@ -319,6 +319,16 @@ function extract_stroke(paths, endpoint_map, bridge_adjacency,
     return endpoint_map[Point.key(index)].point;
   }
 
+  function push_line_segments(points) {
+    for (var i = 0; i < points.length - 1; i++) {
+      result.push({
+        start: Point.clone(points[i]),
+        end: Point.clone(points[i + 1]),
+        control: undefined,
+      });
+    }
+  }
+
   function select_bridge(endpoint, options) {
     if (options.length === 1) {
       // Handle star-shaped strokes where one stroke ends at the intersection
@@ -335,22 +345,25 @@ function extract_stroke(paths, endpoint_map, bridge_adjacency,
           }
           // Compute the other bridge segment and check if it intersects.
           var indices2 = [endpoint_map[key].index, bridge_adjacency[key][i]];
+          var segment2 = indices2.map(index_to_point);
           if (Point.equal(indices2[0], indices1[1]) &&
               !extracted_indices[Point.key(indices2[1])]) {
+            push_line_segments([segment1[0], segment1[1], segment2[1]]);
             return indices2[1];
           } else if (Point.equal(indices2[1], indices1[1]) &&
                      !extracted_indices[Point.key(indices2[0])]) {
+            push_line_segments([segment1[0], segment1[1], segment2[0]]);
             return indices2[0];
           }
-          var segment2 = indices2.map(index_to_point);
           var intersection = get_intersection(segment1, segment2);
           if (intersection !== undefined) {
             var angle1 = angle(indices1[0], indices1[1]);
             var angle2 = angle(indices2[0], indices2[1]);
-            var diff = Angle.subtract(angle2, angle1);
-            if (diff < 0) {
+            if (Angle.subtract(angle2, angle1) < 0) {
               indices2.reverse();
+              segment2.reverse();
             }
+            push_line_segments([segment1[0], intersection, segment2[1]]);
             return indices2[1];
           }
         }
@@ -382,12 +395,18 @@ function extract_stroke(paths, endpoint_map, bridge_adjacency,
       var options = bridge_adjacency[key].sort(function(a, b) {
         return angle(endpoint.index, a) - angle(endpoint.index, b);
       });
+      // HACK(skishore): The call to select_bridge may update the result.
+      // When a stroke is formed by computing a bridge intersection, then the
+      // two bridge fragments are added in select_bridge.
+      var result_length = result.length;
       var next = (attempt_one ? options[0] : select_bridge(endpoint, options));
-      result.push({
-        start: Point.clone(endpoint.point),
-        end: Point.clone(endpoint_map[Point.key(next)].point),
-        control: undefined,
-      });
+      if (result.length === result_length) {
+        result.push({
+          start: Point.clone(endpoint.point),
+          end: Point.clone(endpoint_map[Point.key(next)].point),
+          control: undefined,
+        });
+      }
       current = next;
     }
     // Check if we have either closed the loop or hit an extracted segment.