[librsvg/rustification] bgo#763386: Handle missing case of coincident control points

[Federico Mena Quintero <federico src gnome org>]

commit 7714dfe8aa6836ab59f78cdd7eb00a814897e21e
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Dec 14 13:27:05 2016 -0600

    bgo#763386: Handle missing case of coincident control points
    
    ... are we done with these yet?
    
    Thanks again to Massimo for pointing out this case in
    https://bugzilla.gnome.org/show_bug.cgi?id=763386#c4

 rust/src/marker.rs                                 |   42 +++++++++++++++++--
 .../reftests/bugs/763386-marker-coincident-ref.png |  Bin 943 -> 1198 bytes
 .../reftests/bugs/763386-marker-coincident.svg     |    4 +-
 3 files changed, 40 insertions(+), 6 deletions(-)
---
diff --git a/rust/src/marker.rs b/rust/src/marker.rs
index 665680f..f0067ad 100644
--- a/rust/src/marker.rs
+++ b/rust/src/marker.rs
@@ -193,18 +193,41 @@ fn get_segment_directionalities (segment: &Segment) -> Option <(f64, f64, f64, f
         Segment::Degenerate { .. } => { None },
 
         Segment::LineOrCurve { x1, y1, x2, y2, x3, y3, x4, y4 } => {
-            if points_equal (x1, y1, x2, y2) && points_equal (x1, y1, x3, y3) && points_equal (x1, y1, x4, 
y4) {
+            let coincide_1_and_2 = points_equal (x1, y1, x2, y2);
+            let coincide_1_and_3 = points_equal (x1, y1, x3, y3);
+            let coincide_1_and_4 = points_equal (x1, y1, x4, y4);
+            let coincide_2_and_3 = points_equal (x2, y2, x3, y3);
+            let coincide_2_and_4 = points_equal (x2, y2, x4, y4);
+            let coincide_3_and_4 = points_equal (x3, y3, x4, y4);
+
+            if coincide_1_and_2 && coincide_1_and_3 && coincide_1_and_4 {
+
                 None
-            } else if points_equal (x1, y1, x2, y2) && points_equal (x1, y1, x3, y3) {
+
+            } else if coincide_1_and_2 && coincide_1_and_3 {
+
                 Some ((x4 - x1, y4 - y1, x4 - x3, y4 - y3))
-            } else if points_equal (x2, y2, x3, y3) && points_equal (x2, y2, x4, y4) {
+
+            } else if coincide_1_and_2 && coincide_3_and_4 {
+
+                Some ((x4 - x1, y4 - y1, x4 - x1, y4 - y1))
+
+            } else if coincide_2_and_3 && coincide_2_and_4 {
+
                 Some ((x2 - x1, y2 - y1, x4 - x1, y4 - y1))
-            } else if points_equal (x1, y1, x2, y2) {
+
+            } else if coincide_1_and_2 {
+
                 Some  ((x3 - x1, y3 - y1, x4 - x3, y4 - y3))
-            } else if points_equal (x3, y3, x4, y4) {
+
+            } else if coincide_3_and_4 {
+
                 Some ((x2 - x1, y2 - y1, x4 - x2, y4 - y2))
+
             } else {
+
                 Some ((x2 - x1, y2 - y1, x4 - x3, y4 - y3))
+
             }
         }
     }
@@ -728,4 +751,13 @@ mod tests {
         assert_eq! ((-20.0, -40.0), (v1x, v1y));
         assert_eq! ((-20.0, -40.0), (v2x, v2y));
     }
+
+    #[test]
+    fn curve_with_12_34_coincident_has_directionality () {
+        let (v1x, v1y, v2x, v2y) =
+            super::get_segment_directionalities (&curve (20.0, 40.0, 20.0, 40.0, 60.0, 70.0, 60.0, 
70.0)).unwrap ();
+
+        assert_eq! ((40.0, 30.0), (v1x, v1y));
+        assert_eq! ((40.0, 30.0), (v2x, v2y));
+    }
 }
diff --git a/tests/fixtures/reftests/bugs/763386-marker-coincident-ref.png 
b/tests/fixtures/reftests/bugs/763386-marker-coincident-ref.png
index 09e8852..2248fd7 100644
Binary files a/tests/fixtures/reftests/bugs/763386-marker-coincident-ref.png and 
b/tests/fixtures/reftests/bugs/763386-marker-coincident-ref.png differ
diff --git a/tests/fixtures/reftests/bugs/763386-marker-coincident.svg 
b/tests/fixtures/reftests/bugs/763386-marker-coincident.svg
index 6829102..7af4f9e 100644
--- a/tests/fixtures/reftests/bugs/763386-marker-coincident.svg
+++ b/tests/fixtures/reftests/bugs/763386-marker-coincident.svg
@@ -1,6 +1,6 @@
 <svg xmlns="http://www.w3.org/2000/svg";
      xmlns:xlink="http://www.w3.org/1999/xlink";
-     viewBox="0 0 130 64">
+     viewBox="0 0 130 130">
     <marker id="marker"
             viewBox="-4 -4 8 8"
             orient="auto">
@@ -10,4 +10,6 @@
           stroke="red" d="M 12,12 c 0,0 0,0 40,40"/>
     <path stroke-width="8" marker-start="url(#marker)" marker-end="url(#marker)"
           stroke="red" d="M 118,12 c -40,40 -40,40 -40,40"/>
+    <path stroke-width="8" marker-start="url(#marker)" marker-end="url(#marker)"
+          stroke="red" d="M 12,70 c 0,0 40,40 40,40"/>
 </svg>