From f1a066f4c112b3783d5a52a6a91badd8e956a312 Mon Sep 17 00:00:00 2001
From: Nicola Fontana <ntd@entidi.it>
Date: Sun, 28 Jun 2009 21:02:09 +0200
Subject: [PATCH] [CpmlArc] Added cpml_arc_length()

Implemented the arc length computation. The algorithm is quite trivial:
the length is directly proportional to the angle delta of the arc and
the proportion is applied to the whole circumference:

length = delta / 2PI * circumference = delta * radius
---
 cpml/cpml-arc.c | 23 +++++++++++++++++++++++
 cpml/cpml-arc.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/cpml/cpml-arc.c b/cpml/cpml-arc.c
index 51e241d6..743ed924 100644
--- a/cpml/cpml-arc.c
+++ b/cpml/cpml-arc.c
@@ -162,6 +162,29 @@ cpml_arc_info(const CpmlPrimitive *arc, CpmlPair *center,
 }
 
 /**
+ * cpml_arc_length:
+ * @arc:  the #CpmlPrimitive arc data
+ *
+ * Given the @arc primitive, returns its length.
+ *
+ * Return value: the requested length or 0 on errors
+ **/
+double
+cpml_arc_length(const CpmlPrimitive *arc)
+{
+    double r, start, end, delta;
+
+    if (!cpml_arc_info(arc, NULL, &r, &start, &end) || start == end)
+        return 0.;
+
+    delta = end - start;
+    if (delta < 0)
+        delta += M_PI*2;
+
+    return r*delta;
+}
+
+/**
  * cpml_arc_pair_at:
  * @arc:  the #CpmlPrimitive arc data
  * @pair: the destination #CpmlPair
diff --git a/cpml/cpml-arc.h b/cpml/cpml-arc.h
index 02348dd1..80ea7f58 100644
--- a/cpml/cpml-arc.h
+++ b/cpml/cpml-arc.h
@@ -40,6 +40,7 @@ cairo_bool_t
                                          double                 *r,
                                          double                 *start,
                                          double                 *end);
+double  cpml_arc_length                 (const CpmlPrimitive    *arc);
 void    cpml_arc_pair_at                (const CpmlPrimitive    *arc,
                                          CpmlPair               *pair,
                                          double                  pos);
-- 
2.11.4.GIT