fix compilation failure when using lensfun 0.2.x

Fixes #4085

CMakeLists.txt

@@ -445,6 +445,19 @@ if(UNIX)
     install(FILES rawtherapee.appdata.xml DESTINATION "${APPDATADIR}")
 endif()
 
+# check whether the used version of lensfun has lfDatabase::LoadDirectory
+include(CheckCXXSourceCompiles)
+set(CMAKE_REQUIRED_INCLUDES ${LENSFUN_INCLUDE_DIRS})
+check_cxx_source_compiles(
+    "#include <lensfun.h>
+int main()
+{
+    lfDatabase *db = 0;
+    bool b = db->LoadDirectory(0);
+    return 0;
+}" LENSFUN_HAS_LOAD_DIRECTORY)
+
+
 add_subdirectory(rtexif)
 add_subdirectory(rtengine)
 add_subdirectory(rtgui)

rtengine/CMakeLists.txt

@@ -113,6 +113,11 @@ set(RTENGINESOURCEFILES
     rtlensfun.cc
     )
 
+if(LENSFUN_HAS_LOAD_DIRECTORY)
+    set_source_files_properties(rtlensfun.cc PROPERTIES COMPILE_DEFINITIONS RT_LENSFUN_HAS_LOAD_DIRECTORY)
+endif()
+
+
 if(NOT WITH_SYSTEM_KLT)
     set(RTENGINESOURCEFILES ${RTENGINESOURCEFILES}
         klt/convolve.cc

rtengine/rtlensfun.cc

@@ -267,7 +267,12 @@ bool LFDatabase::init(const Glib::ustring &dbdir)
         std::cout << "..." << std::flush;
     }
 
-    bool ok = dbdir.empty() ? (instance_.data_->Load() ==  LF_NO_ERROR) : instance_.data_->LoadDirectory(dbdir.c_str());
+    bool ok = false;
+    if (dbdir.empty()) {
+        ok = (instance_.data_->Load() ==  LF_NO_ERROR);
+    } else {
+        ok = instance_.LoadDirectory(dbdir.c_str());
+    }
 
     if (settings->verbose) {
         std::cout << (ok ? "OK" : "FAIL") << std::endl;
@@ -277,6 +282,43 @@ bool LFDatabase::init(const Glib::ustring &dbdir)
 }
 
 
+bool LFDatabase::LoadDirectory(const char *dirname)
+{
+#if RT_LENSFUN_HAS_LOAD_DIRECTORY
+    instance_.data_->LoadDirectory(dirname);
+#else
+    // backported from lensfun 0.3.x
+    bool database_found = false;
+
+    GDir *dir = g_dir_open (dirname, 0, NULL);
+    if (dir)
+    {
+        GPatternSpec *ps = g_pattern_spec_new ("*.xml");
+        if (ps)
+        {
+            const gchar *fn;
+            while ((fn = g_dir_read_name (dir)))
+            {
+                size_t sl = strlen (fn);
+                if (g_pattern_match (ps, sl, fn, NULL))
+                {
+                    gchar *ffn = g_build_filename (dirname, fn, NULL);
+                    /* Ignore errors */
+                    if (data_->Load (ffn) == LF_NO_ERROR)
+                        database_found = true;
+                    g_free (ffn);
+                }
+            }
+            g_pattern_spec_free (ps);
+        }
+        g_dir_close (dir);
+    }
+
+    return database_found;
+#endif
+}
+
+
 LFDatabase::LFDatabase():
     data_(nullptr)
 {

rtengine/rtlensfun.h

@@ -117,6 +117,8 @@ private:
                                             float focalLen, float aperture, float focusDist,
                                             int width, int height, bool swap_xy) const;
     LFDatabase();
+    bool LoadDirectory(const char *dirname);
+    
     static LFDatabase instance_;
     lfDatabase *data_;
 };