X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fevoral%2Fevoral%2FTimeConverter.hpp;h=6c02507c174aaf2b52544104b3be038e9dca3d96;hb=22fd92f97c5ff2bb1890a3b88085bed5c035498e;hp=3f434d9dd7f2f4f20316bfafa67659caaa150d58;hpb=3963d2b0b224e79fdf8e852e39fc3a765fa1431b;p=ardour.git

diff --git a/libs/evoral/evoral/TimeConverter.hpp b/libs/evoral/evoral/TimeConverter.hpp
index 3f434d9dd7..6c02507c17 100644
--- a/libs/evoral/evoral/TimeConverter.hpp
+++ b/libs/evoral/evoral/TimeConverter.hpp
@@ -1,16 +1,16 @@
 /* This file is part of Evoral.
- * Copyright (C) 2009 Dave Robillard <http://drobilla.net>
+ * Copyright (C) 2009 David Robillard <http://drobilla.net>
  * Copyright (C) 2009 Paul Davis
- * 
+ *
  * Evoral 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.
- * 
+ *
  * Evoral 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 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.,
  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
@@ -19,25 +19,61 @@
 #ifndef EVORAL_TIME_CONVERTER_HPP
 #define EVORAL_TIME_CONVERTER_HPP
 
+#include "evoral/visibility.h"
+
 namespace Evoral {
 
 /** A bidirectional converter between two different time units.
  *
  * Think of the conversion method names as if they are written in-between
  * the two template parameters (i.e. "A <name> B").
+ *
+ * _origin_b should be the origin for conversion in the units of B.
+ * That is, there is some point in time _origin_b, such that:
+ *
+ *    to()   converts a time _origin_b + a into an offset from _origin_b in units of B.
+ *    from() converts a time _origin_b + b into an offset from _origin_b in units of A.
  */
 template<typename A, typename B>
-class TimeConverter {
+class LIBEVORAL_TEMPLATE_API TimeConverter {
 public:
-	virtual ~TimeConverter() {}
+	TimeConverter () : _origin_b (0) {}
+	TimeConverter (B ob) : _origin_b (ob) {}
+	virtual ~TimeConverter();
 
 	/** Convert A time to B time (A to B) */
 	virtual B to(A a) const = 0;
-	
+
 	/** Convert B time to A time (A from B) */
 	virtual A from(B b) const = 0;
+
+	B origin_b () const {
+		return _origin_b;
+	}
+
+	void set_origin_b (B o) {
+		_origin_b = o;
+	}
+
+protected:
+	B _origin_b;
+};
+
+
+/** A stub TimeConverter that simple statically casts between types.
+ *  _origin_b has no bearing here, as there is no time conversion
+ *  going on.
+ */
+template<typename A, typename B>
+class LIBEVORAL_TEMPLATE_API IdentityConverter : public TimeConverter<A,B> {
+  public:
+	IdentityConverter() {}
+
+	B to(A a)   const;
+	A from(B b) const;
 };
 
+
 } // namespace Evoral
 
 #endif // EVORAL_TIME_CONVERTER_HPP