From f0b76079535de65a7cd4f9467b5cabc40c12cf54 Mon Sep 17 00:00:00 2001
From: rachytski <siarhei.rachytski@gmail.com>
Date: Sun, 11 Mar 2012 16:57:51 +0400
Subject: [PATCH] optimizing OverlayElements packing. more elements should be
 displayed without additional drawing penalty.

---
 yg/info_layer.cpp | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/yg/info_layer.cpp b/yg/info_layer.cpp
index d044ec8076..c47c64ad25 100644
--- a/yg/info_layer.cpp
+++ b/yg/info_layer.cpp
@@ -214,17 +214,27 @@ namespace yg
     }
   }
 
-  void InfoLayer::merge(InfoLayer const & layer, math::Matrix<double, 3, 3> const & m)
-  {
-    layer.m_tree.ForEach(bind(&InfoLayer::processOverlayElement, this, _1, cref(m)));
-  }
-
   bool greater_priority(shared_ptr<OverlayElement> const & l,
                         shared_ptr<OverlayElement> const & r)
   {
     return l->visualRank() > r->visualRank();
   }
 
+  void InfoLayer::merge(InfoLayer const & layer, math::Matrix<double, 3, 3> const & m)
+  {
+    vector<shared_ptr<OverlayElement> > v;
+
+    /// 1. collecting all elements from tree
+    layer.m_tree.ForEach(MakeBackInsertFunctor(v));
+
+    /// 2. sorting by priority, so the more important ones comes first
+    sort(v.begin(), v.end(), &greater_priority);
+
+    /// 3. merging them into the infoLayer starting from most
+    /// important one to optimize the space usage.
+    for_each(v.begin(), v.end(), bind(&InfoLayer::processOverlayElement, this, _1, cref(m)));
+  }
+
   void InfoLayer::cache(ResourceStyleCache * stylesCache)
   {
     /// collecting elements into vector sorted by visualPriority