1 files changed, 41 insertions, 25 deletions

diff --git a/src/2geom/linear.h b/src/2geom/linear.h
index 8c154364e..b0306fb9f 100644
--- a/src/2geom/linear.h
+++ b/src/2geom/linear.h
@@ -1,7 +1,7 @@
 /**
  * \file
  * \brief  Linear fragment function class
- *
+ *//*
  *  Authors:
  *   Nathan Hurst <njh@mail.csse.monash.edu.au>
  *   Michael Sloan <mgsloan@gmail.com>
@@ -32,12 +32,12 @@
  * the specific language governing rights and limitations.
  */
 
-#ifndef SEEN_LINEAR_H
-#define SEEN_LINEAR_H
+#ifndef LIB2GEOM_SEEN_LINEAR_H
+#define LIB2GEOM_SEEN_LINEAR_H
+
 #include <2geom/interval.h>
 #include <2geom/math-utils.h>
 
-
 //#define USE_SBASIS_OF
 
 #ifdef USE_SBASIS_OF
@@ -46,48 +46,60 @@
 
 #else
 
-namespace Geom{
-
-inline double lerp(double t, double a, double b) { return a*(1-t) + b*t; }
+namespace Geom {
 
 class SBasis;
 
-class Linear{
+/**
+ * @brief Function that interpolates linearly between two values.
+ * @ingroup Fragments
+ */
+class Linear {
 public:
     double a[2];
     Linear() {a[0]=0; a[1]=0;}
     Linear(double aa, double b) {a[0] = aa; a[1] = b;}
     Linear(double aa) {a[0] = aa; a[1] = aa;}
 
-    double operator[](const int i) const {
-        assert(i >= 0);
+    double operator[](unsigned i) const {
         assert(i < 2);
         return a[i];
     }
-    double& operator[](const int i) {
-        assert(i >= 0);
+    double &operator[](unsigned i) {
         assert(i < 2);
         return a[i];
     }
 
     //IMPL: FragmentConcept
     typedef double output_type;
-    inline bool isZero(double eps=EPSILON) const { return are_near(a[0], 0., eps) && are_near(a[1], 0., eps); }
-    inline bool isConstant(double eps=EPSILON) const { return are_near(a[0], a[1], eps); }
-    inline bool isFinite() const { return IS_FINITE(a[0]) && IS_FINITE(a[1]); }
-
-    inline double at0() const { return a[0]; }
-    inline double at1() const { return a[1]; }
-
-    inline double valueAt(double t) const { return lerp(t, a[0], a[1]); }
-    inline double operator()(double t) const { return valueAt(t); }
+    bool isZero(double eps=EPSILON) const { return are_near(a[0], 0., eps) && are_near(a[1], 0., eps); }
+    bool isConstant(double eps=EPSILON) const { return are_near(a[0], a[1], eps); }
+    bool isFinite() const { return IS_FINITE(a[0]) && IS_FINITE(a[1]); }
+
+    Coord at0() const { return a[0]; }
+    Coord &at0() { return a[0]; }
+    Coord at1() const { return a[1]; }
+    Coord &at1() { return a[1]; }
+
+    double valueAt(double t) const { return lerp(t, a[0], a[1]); }
+    double operator()(double t) const { return valueAt(t); }
+
+    // not very useful, but required for ShapeConcept
+    std::vector<Coord> valueAndDerivatives(Coord t, unsigned n) {
+        std::vector<Coord> result(n+1, 0.0);
+        result[0] = valueAt(t);
+        if (n >= 1) {
+            result[1] = a[1] - a[0];
+        }
+        return result;
+    }
 
     //defined in sbasis.h
     inline SBasis toSBasis() const;
 
-    inline OptInterval bounds_exact() const { return Interval(a[0], a[1]); }
-    inline OptInterval bounds_fast() const { return bounds_exact(); }
-    inline OptInterval bounds_local(double u, double v) const { return Interval(valueAt(u), valueAt(v)); }
+    OptInterval bounds_exact() const { return Interval(a[0], a[1]); }
+    OptInterval bounds_fast() const { return bounds_exact(); }
+    OptInterval bounds_local(double u, double v) const { return Interval(valueAt(u), valueAt(v)); }
 
     double tri() const {
         return a[1] - a[0];
@@ -98,6 +110,10 @@ public:
 };
 
 inline Linear reverse(Linear const &a) { return Linear(a[1], a[0]); }
+inline Linear portion(Linear const &a, Coord from, Coord to) {
+    Linear result(a.valueAt(from), a.valueAt(to));
+    return result;
+}
 
 //IMPL: AddableConcept
 inline Linear operator+(Linear const & a, Linear const & b) {
@@ -158,7 +174,7 @@ inline Linear operator/=(Linear & a, double b) {
 }
 #endif
 
-#endif //SEEN_LINEAR_H
+#endif //LIB2GEOM_SEEN_LINEAR_H
 
 /*
   Local Variables: