From f527cde6342c5b8109a20f0a6b483327c6569844 Mon Sep 17 00:00:00 2001
From: salinasd <salinasd@636b058d-ea47-450e-bf9e-a15bfbe3eedb>
Date: Tue, 27 Jan 2015 10:20:13 +0000
Subject: Merge GudhUI, a UI for gudhi based on Qt

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/trunk@427 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 17fedd974f14a8225b27d94361e835964eeb5cba
---
 src/GudhUI/utils/Edge_collapsor.h | 84 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 src/GudhUI/utils/Edge_collapsor.h

(limited to 'src/GudhUI/utils/Edge_collapsor.h')

diff --git a/src/GudhUI/utils/Edge_collapsor.h b/src/GudhUI/utils/Edge_collapsor.h
new file mode 100644
index 00000000..9cf880e0
--- /dev/null
+++ b/src/GudhUI/utils/Edge_collapsor.h
@@ -0,0 +1,84 @@
+/*
+ * Collapsor.h
+ *
+ *  Created on: Sep 25, 2014
+ *      Author: dsalinas
+ */
+
+#ifndef COLLAPSOR_H_
+#define COLLAPSOR_H_
+
+#include <list>
+#include "utils/Edge_contractor.h"
+
+/**
+ * Iteratively puts every vertex at the center of its neighbors
+ */
+template<typename SkBlComplex> class Edge_collapsor{
+private:
+	SkBlComplex& complex_;
+	unsigned num_collapses_;
+public:
+	typedef typename SkBlComplex::Vertex_handle Vertex_handle;
+	typedef typename SkBlComplex::Edge_handle Edge_handle;
+
+	/**
+	 * @brief Modify complex to be the expansion of the k-nearest neighbor
+	 * symetric graph.
+	 */
+	Edge_collapsor(SkBlComplex& complex,unsigned num_collapses):
+		complex_(complex),num_collapses_(num_collapses)
+	{
+		std::list<Edge_handle> edges;
+		edges.insert(edges.begin(),complex_.edge_range().begin(),complex_.edge_range().end());
+
+		edges.sort(
+				[&](Edge_handle e1,Edge_handle e2){
+			return squared_edge_length(e1) < squared_edge_length(e2);
+		});
+
+		collapse_edges(edges);
+
+	}
+
+private:
+
+
+	void collapse_edges(std::list<Edge_handle>& edges){
+		while(!edges.empty() && num_collapses_--){
+			Edge_handle current_edge = edges.front();
+			edges.pop_front();
+			if(is_link_reducible(current_edge))
+				complex_.remove_edge(current_edge);
+		}
+
+	}
+
+	bool is_link_reducible(Edge_handle e){
+		auto link = complex_.link(e);
+
+		if(link.empty()) return false;
+
+		if(link.is_cone()) return true;
+
+		if(link.num_connected_components()>1) return false;
+
+		Edge_contractor<Complex> contractor(link,link.num_vertices()-1);
+
+		return (link.num_vertices()==1);
+	}
+
+
+	double squared_edge_length(Edge_handle e) const{
+		return squared_eucl_distance(complex_.point(complex_.first_vertex(e)),complex_.point(complex_.second_vertex(e)));
+	}
+
+	double squared_eucl_distance(const Point& p1,const Point& p2) const{
+		return Geometry_trait::Squared_distance_d()(p1,p2);
+	}
+
+};
+
+
+
+#endif /* COLLAPSOR_H_ */
-- 
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