added a max_value attribute to color_band to handle the case of the last band more gracefully

bindings/python/mapnik_raster_colorizer.cpp

@@ -48,6 +48,14 @@ namespace {
    {
       rc->append_band(v, c, m);
    }
+   void append_band5(raster_colorizer_ptr & rc, float v, float vm, color c, unsigned m)
+   {
+      rc->append_band(v, vm, c, m);
+   }
+   void append_band6(raster_colorizer_ptr & rc, float v, float vm, color c)
+   {
+      rc->append_band(v, vm, c);
+   }
    color_bands const& get_color_bands(raster_colorizer_ptr & rc)
    {
       return rc->get_color_bands();
@@ -67,6 +75,8 @@ void export_raster_colorizer()
     .def("append_band", append_band2, "TODO: Write docs")
     .def("append_band", append_band3, "TODO: Write docs")
     .def("append_band", append_band4, "TODO: Write docs")
+    .def("append_band", append_band5, "TODO: Write docs")
+    .def("append_band", append_band6, "TODO: Write docs")
     .def("get_color", &raster_colorizer::get_color, "TODO: Write docs")
 	;    
 
@@ -83,6 +93,7 @@ void export_raster_colorizer()
                   (&color_band::get_color,
                    return_value_policy<reference_existing_object>()))
     .add_property("value", &color_band::get_value)
+    .add_property("max_value", &color_band::get_max_value)
     .def(self == self)
     .def("__str__",&color_band::to_string)
     ;

include/mapnik/raster_colorizer.hpp

@@ -37,11 +37,19 @@ namespace mapnik
 struct MAPNIK_DECL color_band
 {
     float value_;
+    float max_value_;
     color color_;
     unsigned midpoints_;
     bool is_interpolated_;
     color_band(float value, color c)
 	: value_(value),
+	max_value_(value),
+	color_(c),
+	midpoints_(0),
+	is_interpolated_(false) {}
+    color_band(float value, float max_value, color c)
+	: value_(value),
+	max_value_(max_value),
 	color_(c),
 	midpoints_(0),
 	is_interpolated_(false) {}
@@ -57,18 +65,22 @@ struct MAPNIK_DECL color_band
     {
 	return value_;
     }
+    const float get_max_value() const
+    {
+	return max_value_;
+    }
     const color& get_color() const
     {
 	return color_;
     }
     bool operator==(color_band const& other) const
     {
-	return value_ == other.value_ && color_ == other.color_;
+	return value_ == other.value_ && color_ == other.color_ && max_value_ == other.max_value_;
     }
     std::string to_string() const
     {
 	std::stringstream ss;
-	ss << color_.to_string() << " " << value_;
+	ss << color_.to_string() << " " << value_ << " " << max_value_;
 	return ss.str();
     }
 };
@@ -101,6 +113,8 @@ struct MAPNIK_DECL raster_colorizer
 		);
 	}
 	colors_.push_back(band);
+	if (colors_.size() > 0 && colors_.back().value_ == colors_.back().max_value_)
+        colors_.back().max_value_ = band.value_;
     }
     void append_band (color_band band, unsigned midpoints)
     {
@@ -141,11 +155,22 @@ struct MAPNIK_DECL raster_colorizer
 	append_band(color_band(value, c));
     }
 
+    void append_band (float value, float max_value, color c)
+    {
+	append_band(color_band(value, max_value, c));
+    }
+
     void append_band (float value, color c, unsigned midpoints)
     {
 	append_band(color_band(value, c), midpoints);
     }
 
+    void append_band (float value, float max_value, color c, unsigned midpoints)
+    {
+	append_band(color_band(value, max_value, c), midpoints);
+    }
+
+
     /* rgba = 
      *   if cs[pos].value <= value < cs[pos+1].value: cs[pos].color
      *   otherwise: transparent
@@ -168,7 +193,7 @@ struct MAPNIK_DECL raster_colorizer
 	}
 	lo--;
 	if ((0 <= lo && lo < last) ||
-	    (lo==last && colors_[last].value_==value))
+	    (lo==last && (colors_[last].value_==value || value<colors_[last].max_value_)))
 	    return colors_[lo].color_;
 	else
 	    return color(0,0,0,0);

src/load_map.cpp

@@ -1605,7 +1605,12 @@ void map_parser::parse_raster_colorizer(raster_colorizer_ptr const& rc,
 		    throw config_error("missing color");
 		}
 		unsigned midpoints = get_attr(cb, "midpoints", 0);
-		rc->append_band(value, *c, midpoints);
+		optional<float> max_value = get_opt_attr<float>(cb, "max_value");
+		if (max_value) {
+            rc->append_band(value, *max_value, *c, midpoints);
+		} else {
+            rc->append_band(value, *c, midpoints);
+        }
 	    }
 	    else if (cb_tag.first != "<xmlcomment>" &&
 		     cb_tag.first != "<xmlattr>" )

src/save_map.cpp

@@ -59,6 +59,8 @@ void serialize_raster_colorizer(ptree & sym_node,
 		ptree::value_type("ColorBand", ptree())
 		)->second;
 	    set_attr(band_node, "value", cb[i].get_value());    
+        if (cb[i].get_value() != cb[i].get_max_value())
+            set_attr(band_node, "max_value", cb[i].get_max_value());    
 	    set_attr(band_node, "midpoints", cb[i].get_midpoints());    
 	    optional<color> c = cb[i].get_color();
 	    if (c) set_attr(band_node, "color", * c);    

tests/python_tests/raster_colorizer_test.py

@@ -30,3 +30,17 @@ def test_get_color():
     eq_(colorizer.get_color(200), bands[-1][1])
     #  values greater than the last value are mapped to "transparent"
     eq_(colorizer.get_color(201), mapnik2.Color("transparent"))
+
+def test_get_color_with_max_value():
+    colorizer = mapnik2.RasterColorizer()
+    c1 = mapnik2.Color("#0044cc")
+    colorizer.append_band(0, c1)
+    c2 = mapnik2.Color("#0055dd")
+    colorizer.append_band(1, 2, c2)
+
+    eq_(colorizer.get_color(-1), mapnik2.Color("transparent"))
+    eq_(colorizer.get_color(0), c1)
+    eq_(colorizer.get_color(0.5), c1)
+    eq_(colorizer.get_color(1), c2)
+    eq_(colorizer.get_color(1.5), c2)
+    eq_(colorizer.get_color(2), mapnik2.Color("transparent"))