ImageAttrHandlerHDF5.h

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00001 //# ImageAttrHandlerHDF5.h: Attributes handler for HDF5 images
00002 //# Copyright (C) 2012
00003 //# Associated Universities, Inc. Washington DC, USA.
00004 //#
00005 //# This library is free software; you can redistribute it and/or modify it
00006 //# under the terms of the GNU Library General Public License as published by
00007 //# the Free Software Foundation; either version 2 of the License, or (at your
00008 //# option) any later version.
00009 //#
00010 //# This library is distributed in the hope that it will be useful, but WITHOUT
00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
00012 //# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
00013 //# License for more details.
00014 //#
00015 //# You should have received a copy of the GNU Library General Public License
00016 //# along with this library; if not, write to the Free Software Foundation,
00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
00018 //#
00019 //# Correspondence concerning AIPS++ should be addressed as follows:
00020 //#        Internet email: aips2-request@nrao.edu.
00021 //#        Postal address: AIPS++ Project Office
00022 //#                        National Radio Astronomy Observatory
00023 //#                        520 Edgemont Road
00024 //#                        Charlottesville, VA 22903-2475 USA
00025 //#
00026 //# $Id$
00027 
00028 #ifndef IMAGES_IMAGEATTRHANDLERHDF5_H
00029 #define IMAGES_IMAGEATTRHANDLERHDF5_H
00030 
00031 
00032 //# Includes
00033 #include <casacore/casa/aips.h>
00034 #include <casacore/images/Images/ImageAttrHandler.h>
00035 #include <casacore/images/Images/ImageAttrGroupHDF5.h>
00036 #include <casacore/casa/HDF5/HDF5Group.h>
00037 #include <casacore/casa/Utilities/CountedPtr.h>
00038 #include <map>
00039 
00040 namespace casacore {
00041 
00042 // <summary>
00043 // Abstract base class for an image attributes handler.
00044 // </summary>
00045 
00046 // <use visibility=export>
00047 
00048 // <reviewed reviewer="" date="" tests="tPagedmage.cc" demos="dPagedImage.cc">
00049 // </reviewed>
00050 
00051 // <prerequisite>
00052 //   <li> <linkto class=ImageInterface>ImageInterface</linkto>
00053 // </prerequisite>
00054 
00055 // <etymology>
00056 // This class makes it possible to store extra attributes with an image to
00057 // describe atrbitrary meta information.
00058 // </etymology>
00059 
00060 // <synopsis> 
00061 // For LOFAR it was needed to store extra meta information and to be able to
00062 // convert it from casacore table format to HDF5 format and vice-versa.
00063 // Furthermore, it must be possible to access the information in a way that
00064 // arbitrary info can be stored and retrieved.
00065 //
00066 // The attributes are divided into handlers. Each handler can reside in a subtable
00067 // of the image or in a handler in HDF5. All attributes in a handler have the
00068 // same number of values, where each value can be a scalar or (small) array.
00069 // It is possible to define units and measure info for an attribute.
00070 // </synopsis> 
00071 
00072 // <example>
00073 // This example shows how to get attributes from an image.
00074 // make it known to the image.
00075 // <srcblock>
00076 //   // Open the image (as readonly for the moment).
00077 //   PagedImage<Float> myimage ("image.name");
00078 //   // Get access to attibute handler LOFAR_SOURCE.
00079 //   ImageExtrAttr& = myimage.attrHandler ("LOFAR_SOURCE");
00080 //   // Get the data for some field.
00081 //   Vector<String> names = ImageExtrAttr->getString("NAME");
00082 // </srcblock>
00083 // </example>
00084 //
00085 // <motivation>
00086 // LOFAR needed functionality to store arbitrary attributes.
00087 // </motivation>
00088 
00089 class ImageAttrHandlerHDF5 : public ImageAttrHandler
00090 {
00091 public: 
00092   // Default construct from the image table.
00093   ImageAttrHandlerHDF5();
00094 
00095   // Attach the table and return this object.
00096   // It looks for the table keyword ATTRGROUPS which contains the subtables
00097   // defining the attribute groups.
00098   // If the keyword does not exist, it will be added if <src>createHandler</src>
00099   // is set.
00100   // Otherwise the handler is an empty one and no groups can be added to it.
00101   ImageAttrHandlerHDF5& attachTable (const Table& image,
00102                                      Bool createHandler = False);
00103 
00104   virtual ~ImageAttrHandlerHDF5();
00105 
00106   // Attach the hid and return this object.
00107   // It looks for the group ATTRGROUPS which contains groups
00108   // defining the attribute groups.
00109   // If the group does not exist, it will be added if <src>createHandler</src>
00110   // is set.
00111   // Otherwise the handler is an empty one and no groups can be added to it.
00112   ImageAttrHandlerHDF5& attachHid (const HDF5Object& hid,
00113                                    Bool createHandler,
00114                                    Bool isWritable);
00115 
00116   // Flush the attibrutes if needed.
00117   virtual void flush();
00118 
00119   // Test if the given attribute group is present.
00120   virtual Bool hasGroup (const String& name);
00121 
00122   // Get all attribute group names.
00123   virtual Vector<String> groupNames() const;
00124 
00125   // Get access to a group.
00126   virtual ImageAttrGroup& openGroup (const String& groupName);
00127 
00128   // Create an attribute group with the given name.
00129   virtual ImageAttrGroup& createGroup (const String& groupName);
00130 
00131   // Close the group with the given name. It will flush its attributes.
00132   // Nothing is done if it is not open.
00133   virtual void closeGroup (const String& groupName);
00134 
00135 private:
00136   Bool                                itsCanWrite;    //# writable?
00137   CountedPtr<HDF5Group>               itsGroup;       //# HDF5 group to add to
00138   std::map<String,ImageAttrGroupHDF5> itsGroupMap;    //# attribute groups
00139 };
00140 
00141 } //# NAMESPACE CASACORE - END
00142 
00143 #endif
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