From cdefee3524ed510ab61cbacda939c1e325520323 Mon Sep 17 00:00:00 2001
From: Jiri Drbalek <jiri.drbalek@firma.seznam.cz>
Date: Fri, 2 Dec 2016 15:55:50 +0000
Subject: [PATCH 1/2] remove redundant code

---
 src/text/symbolizer_helpers.cpp | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/text/symbolizer_helpers.cpp b/src/text/symbolizer_helpers.cpp
index fe5568ad2..80e4b2dd2 100644
--- a/src/text/symbolizer_helpers.cpp
+++ b/src/text/symbolizer_helpers.cpp
@@ -189,12 +189,6 @@ base_symbolizer_helper::base_symbolizer_helper(
 
 struct largest_bbox_first
 {
-    bool operator() (geometry::geometry<double> const* g0, geometry::geometry<double> const* g1) const
-    {
-        box2d<double> b0 = geometry::envelope(*g0);
-        box2d<double> b1 = geometry::envelope(*g1);
-        return b0.width() * b0.height() > b1.width() * b1.height();
-    }
     bool operator() (base_symbolizer_helper::geometry_cref const& g0,
                      base_symbolizer_helper::geometry_cref const& g1) const
     {

From b5c04cc132b9a9d29e983d53e815a384c2e7ea6c Mon Sep 17 00:00:00 2001
From: Jiri Drbalek <jiri.drbalek@firma.seznam.cz>
Date: Fri, 2 Dec 2016 16:15:07 +0000
Subject: [PATCH 2/2] find max element instead of std::sort

---
 include/mapnik/box2d.hpp        |  1 +
 include/mapnik/box2d_impl.hpp   |  5 +++++
 src/text/symbolizer_helpers.cpp | 35 +++++++++++++++++++++++----------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/include/mapnik/box2d.hpp b/include/mapnik/box2d.hpp
index 267120111..61652839d 100644
--- a/include/mapnik/box2d.hpp
+++ b/include/mapnik/box2d.hpp
@@ -116,6 +116,7 @@ public:
     bool valid() const;
     void move(T x, T y);
     std::string to_string() const;
+    T area() const;
 
     // define some operators
     box2d_type& operator+=(box2d_type const& other);
diff --git a/include/mapnik/box2d_impl.hpp b/include/mapnik/box2d_impl.hpp
index 7f3e9d1e7..4f3117cd1 100644
--- a/include/mapnik/box2d_impl.hpp
+++ b/include/mapnik/box2d_impl.hpp
@@ -393,6 +393,11 @@ std::string box2d<T>::to_string() const
     return s.str();
 }
 
+template <typename T>
+T  box2d<T>::area() const
+{
+    return width() * height();
+}
 
 template <typename T>
 box2d<T>&  box2d<T>::operator+=(box2d<T> const& other)
diff --git a/src/text/symbolizer_helpers.cpp b/src/text/symbolizer_helpers.cpp
index 80e4b2dd2..8064e6c6f 100644
--- a/src/text/symbolizer_helpers.cpp
+++ b/src/text/symbolizer_helpers.cpp
@@ -187,17 +187,26 @@ base_symbolizer_helper::base_symbolizer_helper(
     initialize_points();
 }
 
-struct largest_bbox_first
+template <typename It>
+static It largest_bbox(It begin, It end)
 {
-    bool operator() (base_symbolizer_helper::geometry_cref const& g0,
-                     base_symbolizer_helper::geometry_cref const& g1) const
+    if (begin == end)
     {
-        // TODO - this has got to be expensive! Can we cache bbox's if there are repeated calls to same geom?
-        box2d<double> b0 = geometry::envelope(g0);
-        box2d<double> b1 = geometry::envelope(g1);
-        return b0.width() * b0.height() > b1.width() * b1.height();
+        return end;
     }
-};
+    It largest_geom = begin;
+    double largest_bbox = geometry::envelope(*largest_geom).area();
+    for (++begin; begin != end; ++begin)
+    {
+        double bbox = geometry::envelope(*begin).area();
+        if (bbox > largest_bbox)
+        {
+            largest_bbox = bbox;
+            largest_geom = begin;
+        }
+    }
+    return largest_geom;
+}
 
 void base_symbolizer_helper::initialize_geometries() const
 {
@@ -210,10 +219,16 @@ void base_symbolizer_helper::initialize_geometries() const
             type == geometry::geometry_types::MultiPolygon)
         {
             bool largest_box_only = text_props_->largest_bbox_only;
-            if (largest_box_only)
+            if (largest_box_only && geometries_to_process_.size() > 1)
             {
-                geometries_to_process_.sort(largest_bbox_first());
+                auto largest_geom = largest_bbox(
+                    geometries_to_process_.begin(),
+                    geometries_to_process_.end());
                 geo_itr_ = geometries_to_process_.begin();
+                if (geo_itr_ != largest_geom)
+                {
+                    std::swap(*geo_itr_, *largest_geom);
+                }
                 geometries_to_process_.erase(++geo_itr_, geometries_to_process_.end());
             }
         }