From 81fbe706a620758d88be727e5e6e1696a8631b88 Mon Sep 17 00:00:00 2001
From: Artem Pavlenko <artem@mapnik.org>
Date: Fri, 17 Nov 2006 02:01:21 +0000
Subject: [PATCH] fixed scale_denomitator

---
 include/mapnik/feature_style_processor.hpp |  2 +-
 include/mapnik/scale_denominator.hpp       |  3 +--
 src/layer.cpp                              |  2 +-
 src/scale_denominator.cpp                  | 27 +++++-----------------
 4 files changed, 9 insertions(+), 25 deletions(-)

diff --git a/include/mapnik/feature_style_processor.hpp b/include/mapnik/feature_style_processor.hpp
index 24dc90fae..30d14ee21 100644
--- a/include/mapnik/feature_style_processor.hpp
+++ b/include/mapnik/feature_style_processor.hpp
@@ -76,7 +76,7 @@ namespace mapnik
             try
             {
                 projection proj(m_.srs()); // map projection
-                double scale_denom = scale_denominator(m_,proj);
+                double scale_denom = scale_denominator(m_,proj.is_geographic());
                 std::clog << "scale denominator = " << scale_denom << "\n";
                 
                 std::vector<Layer>::const_iterator itr = m_.layers().begin();
diff --git a/include/mapnik/scale_denominator.hpp b/include/mapnik/scale_denominator.hpp
index 16e3a906a..92fd52c50 100644
--- a/include/mapnik/scale_denominator.hpp
+++ b/include/mapnik/scale_denominator.hpp
@@ -26,6 +26,5 @@
 namespace mapnik {
  
     class Map;
-    class projection;
-    MAPNIK_DECL double scale_denominator(Map const& map,projection const& prj); 
+    MAPNIK_DECL double scale_denominator(Map const& map, bool geographic);
 }
diff --git a/src/layer.cpp b/src/layer.cpp
index 2e66bb91d..f90e81e4f 100644
--- a/src/layer.cpp
+++ b/src/layer.cpp
@@ -173,7 +173,7 @@ namespace mapnik
 
     bool Layer::isVisible(double scale) const
     {
-        return isActive() && scale >= minZoom_ && scale < maxZoom_;
+        return isActive() && scale >= minZoom_ - 1e-6 && scale < maxZoom_ + 1e-6;
     }
 
     void Layer::setSelectable(bool selectable)
diff --git a/src/scale_denominator.cpp b/src/scale_denominator.cpp
index 2c6b2b6a8..01515b6d0 100644
--- a/src/scale_denominator.cpp
+++ b/src/scale_denominator.cpp
@@ -23,32 +23,17 @@
 //$Id$
 #include <cmath>
 #include <mapnik/map.hpp>
-#include <mapnik/projection.hpp>
-#include <mapnik/distance.hpp>
 #include <mapnik/scale_denominator.hpp>
 
 namespace mapnik {
  
-    static const double dpi = 90.0; // display resolution
+    static const double pi = 3.14159265359; 
+    static const double meters_per_degree = 6378137 * 2 * pi/ 360;
     
-    double scale_denominator(Map const& map,projection const& prj)
+    double scale_denominator(Map const& map, bool geographic)
     {
-        double map_width = map.getWidth();
-        double map_height = map.getHeight();
-        Envelope<double> const& extent = map.getCurrentExtent();
-        double x0 = extent.minx();
-        double y0 = extent.miny();
-        double x1 = extent.maxx();
-        double y1 = extent.maxy();
-        
-        if (!prj.is_geographic())
-        {
-            prj.inverse(x0,y0);
-            prj.inverse(x1,y1); 
-        }
-        great_circle_distance distance;
-        double d1 = distance(coord2d(x0,y0),coord2d(x1, y1));
-        double d0 = sqrt(map_width * map_width + map_height * map_height) / dpi * 0.0254;
-        return d1 / d0;
+        double denom = map.scale() / 0.00028;
+        if (geographic) denom *= meters_per_degree;
+        return denom; 
     }
 }