ENH: Adding a GetExtent() method to Layer

Code/UtilitiesAdapters/OGRAdapters/otbOGRLayerWrapper.cxx

@@ -158,6 +158,22 @@ std::string otb::ogr::Layer::GetName() const
 #endif
 }
 
+void otb::ogr::Layer::GetExtent(double& ulx, double& uly, double& lrx, double& lry, bool force) const
+{
+  OGREnvelope sExtent;
+  const OGRErr res = m_Layer->GetExtent(&sExtent,force);
+  if(res != OGRERR_NONE)
+    {
+     itkGenericExceptionMacro(<< "Cannot retrieve extent of layer <"
+                              <<GetName()<<">: " << CPLGetLastErrorMsg());
+    }
+
+  ulx = sExtent.MinX;
+  uly = sExtent.MinY;
+  lrx = sExtent.MaxX;
+  lry = sExtent.MaxY;  
+}
+
 OGRLayer & otb::ogr::Layer::ogr()
 {
   assert(m_Layer && "OGRLayer not initialized");

Code/UtilitiesAdapters/OGRAdapters/otbOGRLayerWrapper.h

@@ -189,6 +189,22 @@ public:
   */
   std::string GetName() const;
 
+  /** Allow to retrieve the extent of the layer
+   *  \param[out] ulx reference to upper-left x coordinate of the
+   *  extent
+   *  \param[out] uly reference to upper-left y coordinate of the
+   *  extent
+   *  \param[out] lrx reference to lower-right x coordinate of the
+   *  extent
+   *  \param[out] uly reference to lower-right y coordinate of the
+   *  extent
+   *  \param[in] force Force computation of the extent if not
+   *  available. May force the driver to walk all geometries to
+   *  compute the extent.
+   *  \throw itk::ExceptionObject if the extent can not be retrieved.
+  */ 
+  void GetExtent(double & ulx, double & uly, double & lrx, double & lry, bool force = false) const;
+
   /** Prints self into stream. */
   void PrintSelf(std::ostream& os, itk::Indent indent) const;