Add example to the User Manual

Convex_hull_2/doc/Convex_hull_2/CGAL/Convex_hull_traits_adapter_2.h

@@ -0,0 +1,62 @@
+namespace CGAL {
+
+/*!
+\ingroup PkgConvexHull2Traits
+
+The class `Convex_hull_traits_adapter_2` serves as a traits class for all the two-dimensional 
+convex hull and extreme point calculation function. This class corresponds 
+to the default traits class for these functions. 
+
+Given a property map associating a key to a point, the class `Convex_hull_traits_adapter_2` enables
+to compute the sequence of keys for which the associted points are the convex hull points , 
+the predicates being computed on the associated points. 
+In other words, the traits provides to a convex hull algorithm a point type which is a key, 
+while the actual point type is `Base_traits::Point_2`. 
+
+\cgalModels `ConvexHullTraits_2`
+
+\sa `CGAL::Convex_hull_constructive_traits_2<R>` 
+\sa `CGAL::Projection_traits_xy_3<K>`
+\sa `CGAL::Projection_traits_yz_3<K>`
+\sa `CGAL::Projection_traits_xz_3<K>`
+
+*/
+template< typename Base_traits, typename PointPropertyMap >
+class Convex_hull_traits_adapter_2 {
+public:
+
+/// \name Types 
+/// @{
+
+/*!
+
+*/ 
+typedef boost::property_traits<PointPropertyMap>::key_type Point_2; 
+
+/// @} 
+
+/// \name Creation 
+/// @{
+
+/*!
+*/ 
+Convex_hull_traits_2(Base_traits base=Base_traits()); 
+
+/*!
+*/ 
+Convex_hull_traits_2(const PointPropertyMap& ppmap, Base_traits base=Base_traits()); 
+/// @} 
+
+/// \name Operations 
+/// @{
+  
+/*!
+Returns a const reference to the point property map. 
+*/ 
+const PointPropertyMap& point_property_map() const; 
+
+
+/// @}
+
+}; /* end Convex_hull_traits_2 */
+} /* end namespace CGAL */

Convex_hull_2/doc/Convex_hull_2/CGAL/convex_hull_traits_2.h

@@ -9,7 +9,8 @@ to the default traits class for these functions.
 
 \cgalModels `ConvexHullTraits_2`
 
-\sa `CGAL::Convex_hull_constructive_traits_2<R>` 
+\sa `CGAL::Convex_hull_constructive_traits_2<R>`
+\sa `CGAL::Convex_hull_traits_adapter_2<R,P>`
 \sa `CGAL::Projection_traits_xy_3<K>`
 \sa `CGAL::Projection_traits_yz_3<K>`
 \sa `CGAL::Projection_traits_xz_3<K>`

Convex_hull_2/doc/Convex_hull_2/Concepts/ConvexHullTraits_2.h

@@ -11,6 +11,7 @@ is specified with each function.
 
 \cgalHasModel `CGAL::Convex_hull_constructive_traits_2<R>`
 \cgalHasModel `CGAL::Convex_hull_traits_2<R>`
+\cgalHasModel `CGAL::Convex_hull_traits_adapter_2<R>`
 \cgalHasModel `CGAL::Projection_traits_xy_3<K>`
 \cgalHasModel `CGAL::Projection_traits_yz_3 <K>`
 \cgalHasModel `CGAL::Projection_traits_xz_3<K>`

Convex_hull_2/doc/Convex_hull_2/Convex_hull_2.txt

@@ -79,6 +79,21 @@ functions such as `ch_bykat()`.
 
 \cgalExample{Convex_hull_2/ch_from_cin_to_cout.cpp}
 
+
+\section Convex_hull_2ExampleIndex  Example using a Property Map
+
+In the following example we have as input a vector of points,
+and we retrieve the indices of of the points which are on the convex hull.
+The convex hull function takes as fourth argument a traits class
+that must be model of the concept `ConvexHullTraits_2`. It provides
+predicates such as orientation tests.
+The class `Convex_hull_traits_adapter_2` in combination with a
+`Pointer_property_map`, is a model. The indices `i` are then "points",
+and the adapter performs the predicates on `points[i]`.
+
+\cgalExample{Convex_hull_2/convex_hull_indices_2.cpp}
+
+
 \section Convex_hull_2Extreme Extreme Points and Hull Subsequences
 
 In addition to the functions for producing convex hulls, there are a

Convex_hull_2/doc/Convex_hull_2/PackageDescription.txt

@@ -69,6 +69,7 @@ defining `CGAL_CH_CHECK_EXPENSIVE`.
 
 - `CGAL::Convex_hull_constructive_traits_2<R>`
 - `CGAL::Convex_hull_traits_2<R>`
+- `CGAL::Convex_hull_traits_adapter_2<R,P>`
 
 \cgalCRPSection{Convex Hull Functions}
 

Convex_hull_2/doc/Convex_hull_2/examples.txt

@@ -1,5 +1,6 @@
 /*!
 \example Convex_hull_2/array_convex_hull_2.cpp
+\example Convex_hull_2/convex_hull_indices_2.cpp
 \example Convex_hull_2/ch_from_cin_to_cout.cpp
 \example Convex_hull_2/ch_graham_anderson.cpp
 \example Convex_hull_2/ch_timing.cpp

Convex_hull_2/examples/Convex_hull_2/convex_hull_indices.cpp

@@ -3,6 +3,7 @@
 #include <CGAL/Convex_hull_traits_adapter_2.h>
 #include <CGAL/property_map.h>
 #include <vector>
+#include <numeric>
 
 typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
 typedef K::Point_2 Point_2;
@@ -11,22 +12,17 @@ typedef CGAL::Convex_hull_traits_adapter_2<K,
 
 int main()
 {
-  std::vector<Point_2> points;
-
-  points.push_back(Point_2(10,0));
-  points.push_back(Point_2(0,10));
-  points.push_back(Point_2(1,1));
-  points.push_back(Point_2(3,4));
-  points.push_back(Point_2(0,0));
-  points.push_back(Point_2(10,10));
-  points.push_back(Point_2(2,6));
+  std::vector<Point_2> points = { Point_2(10,0),
+                                  Point_2(10,0),
+                                  Point_2(0,10),
+                                  Point_2(1,1),
+                                  Point_2(3,4),
+                                  Point_2(0,0),
+                                  Point_2(10,10),
+                                  Point_2(2,6) };
   
   std::vector<std::size_t> indices(points.size()), out;
-
-  for(int i=0; i < indices.size();i++){
-    indices[i] = i;
-  }
-
+  std::iota(indices.begin(), indices.end(),0);
   
   CGAL::convex_hull_2(indices.begin(), indices.end(), std::back_inserter(out),
                       Convex_hull_traits_2(CGAL::make_property_map(points)));