Adds ProjDataInMemory::read_from_file to return a ProjDataInMemory object (#1510)

ProjDataInMemory::read_from_file to return a ProjDataInMemory object

Author: robbietuk

documentation/release_6.3.htm

@@ -48,6 +48,11 @@ <h3>Known problems</h3>
 
 <H2>What is new for developers (aside from what should be obvious from the above):</H2>
 
+<h3>New functionality</h3>
+
+<li>
+  <code>ProjDataInMemory</code> <code>read_from_file</code> method now returns a <code>ProjDataInMemory</code> object.
+</li>
 
 <h3>Changed functionality</h3>
 

src/buildblock/ProjDataInMemory.cxx

@@ -350,6 +350,12 @@ ProjDataInMemory::ProjDataInMemory(const ProjDataInMemory& proj_data)
   std::copy(proj_data.begin_all(), proj_data.end_all(), this->begin_all());
 }
 
+shared_ptr<ProjDataInMemory>
+ProjDataInMemory::read_from_file(const std::string& filename)
+{
+  return std::make_shared<ProjDataInMemory>(*ProjData::read_from_file(filename));
+}
+
 float
 ProjDataInMemory::get_bin_value(Bin& bin)
 {

src/include/stir/ProjDataInMemory.h

@@ -62,6 +62,9 @@ class ProjDataInMemory : public ProjData
   //! Copy constructor
   ProjDataInMemory(const ProjDataInMemory& proj_data);
 
+  //! A static member to get the projection data in memory from a file
+  static shared_ptr<ProjDataInMemory> read_from_file(const std::string& filename);
+
   Viewgram<float> get_viewgram(const int view_num,
                                const int segment_num,
                                const bool make_num_tangential_poss_odd = false,