new file for libmidi++ export control

libs/midi++2/midi++/libmidi_visibility.h

@@ -0,0 +1,56 @@
+/*
+    Copyright (C) 2013 Paul Davis
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef __libmidi_libmidi_visibility_h__
+#define __libmidi_libmidi_visibility_h__
+
+/* _WIN32 is defined by most compilers targetting Windows, but within the
+ * midi source tree, we also define COMPILER_MSVC or COMPILER_MINGW depending
+ * on how a Windows build is built.
+ */
+
+#if defined _WIN32 || defined __CYGWIN__ || defined(COMPILER_MSVC) || defined(COMPILER_MINGW)
+  #define LIBMIDIPP_DLL_IMPORT __declspec(dllimport)
+  #define LIBMIDIPP_DLL_EXPORT __declspec(dllexport)
+  #define LIBMIDIPP_DLL_LOCAL
+#else
+  #if __GNUC__ >= 4
+    #define LIBMIDIPP_DLL_IMPORT __attribute__ ((visibility ("default")))
+    #define LIBMIDIPP_DLL_EXPORT __attribute__ ((visibility ("default")))
+    #define LIBMIDIPP_DLL_LOCAL  __attribute__ ((visibility ("hidden")))
+  #else
+    #define LIBMIDIPP_DLL_IMPORT
+    #define LIBMIDIPP_DLL_EXPORT
+    #define LIBMIDIPP_DLL_LOCAL
+  #endif
+#endif
+
+#ifdef LIBMIDIPP_DLL // libmidi is a DLL
+#ifdef LIBMIDIPP_DLL_EXPORTS // defined if we are building the libmidi DLL (instead of using it)
+    #define LIBMIDIPP_API LIBMIDIPP_DLL_EXPORT
+#else
+    #define LIBMIDIPP_API LIBMIDIPP_DLL_IMPORT
+#endif 
+#define     LIBMIDIPP_LOCAL LIBMIDIPP_DLL_LOCAL
+#else /* static lib, not DLL */
+#define LIBMIDIPP_API
+#define LIBMIDIPP_LOCAL
+#endif
+
+#endif /* __libmidi_libmidi_visibility_h__ */