added HDF4 ISIS NeXus class handling.

CMakeLists.txt

@@ -213,7 +213,35 @@ endif (qt_based_tools)
 if (nexus)
   find_package(HDF5 COMPONENTS CXX REQUIRED)
   if (HAVE_HDF4)
-    find_package(HDF4 REQUIRED)
+    #--- check for HDF4 -----------------------------------------------------------
+    # Find HDF4 manually (pkg-config often doesn't have hdf4)
+    find_path(HDF4_INCLUDE_DIR
+      NAMES mfhdf.h
+      PATHS /usr/include /usr/local/include
+      PATH_SUFFIXES hdf
+    )
+
+    find_library(HDF4_DF_LIBRARY
+      NAMES df libdf
+      PATHS /usr/lib64 /usr/lib /usr/local/lib64 /usr/local/lib
+    )
+
+    find_library(HDF4_MFHDF_LIBRARY
+      NAMES mfhdf libmfhdf
+      PATHS /usr/lib64 /usr/lib /usr/local/lib64 /usr/local/lib
+    )
+
+    if (HDF4_INCLUDE_DIR AND HDF4_DF_LIBRARY AND HDF4_MFHDF_LIBRARY)
+      set(HDF4_FOUND TRUE)
+      set(HDF4_INCLUDE_DIRS ${HDF4_INCLUDE_DIR})
+      set(HDF4_LIBRARIES ${HDF4_MFHDF_LIBRARY} ${HDF4_DF_LIBRARY})
+      message(STATUS "Found HDF4: ${HDF4_INCLUDE_DIR}")
+      message(STATUS "  HDF4 libraries: ${HDF4_LIBRARIES}")
+    else()
+      message(FATAL_ERROR "HDF4 library not found. Please install libhdf4-dev or hdf-devel")
+    endif()
+
+    include_directories(${HDF4_INCLUDE_DIRS})
     add_definitions(-DHAVE_HDF4)
   endif (HAVE_HDF4)  
   add_definitions(-DPNEXUS_ENABLED)