add a clip method to mapnik::box2d

bindings/python/mapnik_envelope.cpp

@@ -84,6 +84,9 @@ box2d<double> (box2d<double>::*intersect)(box2d<double> const&) const = &box2d<d
 void (box2d<double>::*re_center_p1)(double,double) = &box2d<double>::re_center;
 void (box2d<double>::*re_center_p2)(coord<double,2> const& ) = &box2d<double>::re_center;
 
+// clip
+void (box2d<double>::*clip)(box2d<double> const&) = &box2d<double>::clip;
+
 void export_envelope()
 {
     using namespace boost::python;
@@ -144,6 +147,20 @@ void export_envelope()
              ">>> e\n"
              "Box2d(10.0, 10.0, 110.0, 110.0)\n"
             )
+        .def("clip", clip,
+             (arg("other")),
+             "Clip the envelope based on the bounds of another envelope.\n"
+             "\n "
+             "Example:\n"
+             ">>> e = Box2d(0, 0, 100, 100)\n"
+             ">>> e.center(Coord60, 60)\n"
+             ">>> e.center()\n"
+             "Coord(60.0,60.0)\n"
+             ">>> (e.width(), e.height())\n"
+             "(100.0, 100.0)\n"
+             ">>> e\n"
+             "Box2d(10.0, 10.0, 110.0, 110.0)\n"
+            )
         .def("width", width_p1,
              (arg("new_width")),
              "Sets the width to new_width of the envelope preserving its center.\n"

include/mapnik/box2d.hpp

@@ -79,6 +79,7 @@ public:
     void re_center(T cx,T cy);
     void re_center(const coord<T,2>& c);
     void init(T x0,T y0,T x1,T y1);
+    void clip(const box2d_type &other);
     bool from_string(const std::string& s);
     bool valid() const;
         

src/box2d.cpp

@@ -307,6 +307,19 @@ void box2d<T>::init(T x0,T y0,T x1,T y1)
     }
 }
 
+template <typename T>
+#if !defined(__SUNPRO_CC)
+inline
+#endif
+void box2d<T>::clip(const box2d_type& other)
+{
+        minx_ = std::max(minx_,other.minx());
+        miny_ = std::max(miny_,other.miny());
+        maxx_ = std::min(maxx_,other.maxx());
+        maxy_ = std::min(maxy_,other.maxy());
+}
+
+
 template <typename T>
 #if !defined(__SUNPRO_CC)
 inline

tests/python_tests/object_test.py

@@ -674,3 +674,23 @@ def test_envelope_multiplication():
 
     eq_(c.x, 150)
     eq_(c.y, 150)
+
+# Box2d clipping
+def test_envelope_pickle():
+    e1 = mapnik2.Box2d(-180,-90,180,90)
+    e2 = mapnik2.Box2d(-120,40,-110,48)
+    e1.clip(e2)
+    eq_(e1,e2)
+    
+    # madagascar in merc
+    e1 = mapnik2.Box2d(4772116.5490, -2744395.0631, 5765186.4203, -1609458.0673)
+    e2 = mapnik2.Box2d(5124338.3753, -2240522.1727, 5207501.8621, -2130452.8520)
+    e1.clip(e2)
+    eq_(e1,e2)
+    
+    # nz in lon/lat
+    e1 = mapnik2.Box2d(163.8062, -47.1897, 179.3628, -33.9069)
+    e2 = mapnik2.Box2d(173.7378, -39.6395, 174.4849, -38.9252)
+    e1.clip(e2)
+    eq_(e1,e2)
+