X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Flib%2Fdcpomatic_time.h;h=8b2bcce05d0f10cb61d8ece42df965187923ff7c;hb=d0ecbc635fa3931fe6a588c3ffb038d1f3e1b11c;hp=16d93ca28bc83abc01c8273c6ece6cd092b42359;hpb=c8be0644833dce6ff39202430bba0ab358f3e096;p=dcpomatic.git

diff --git a/src/lib/dcpomatic_time.h b/src/lib/dcpomatic_time.h
index 16d93ca28..8b2bcce05 100644
--- a/src/lib/dcpomatic_time.h
+++ b/src/lib/dcpomatic_time.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2014-2016 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2014-2017 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -28,6 +28,7 @@
 #include "frame_rate_change.h"
 #include "dcpomatic_assert.h"
 #include <boost/optional.hpp>
+#include <boost/foreach.hpp>
 #include <stdint.h>
 #include <cmath>
 #include <ostream>
@@ -157,7 +158,13 @@ public:
 		return ::ceil (_t * double(r) / HZ);
 	}
 
-	/** @param r Frames per second */
+	/** Split a time into hours, minutes, seconds and frames.
+	 *  @param r Frames per second.
+	 *  @param h Returned hours.
+	 *  @param m Returned minutes.
+	 *  @param s Returned seconds.
+	 *  @param f Returned frames.
+	 */
 	template <typename T>
 	void split (T r, int& h, int& m, int& s, int& f) const
 	{
@@ -260,7 +267,7 @@ public:
 		return TimePeriod<T> (from + o, to + o);
 	}
 
-	boost::optional<TimePeriod<T> > overlap (TimePeriod<T> const & other) {
+	boost::optional<TimePeriod<T> > overlap (TimePeriod<T> const & other) const {
 		T const max_from = std::max (from, other.from);
 		T const min_to = std::min (to, other.to);
 
@@ -291,6 +298,47 @@ public:
 	}
 };
 
+/** @param A Period which is subtracted from.
+ *  @param B Periods to subtract from `A', must be in ascending order of start time and must not overlap.
+ */
+template <class T>
+std::list<TimePeriod<T> > subtract (TimePeriod<T> A, std::list<TimePeriod<T> > const & B)
+{
+	std::list<TimePeriod<T> > result;
+	result.push_back (A);
+
+	BOOST_FOREACH (TimePeriod<T> i, B) {
+		std::list<TimePeriod<T> > new_result;
+		BOOST_FOREACH (TimePeriod<T> j, result) {
+			boost::optional<TimePeriod<T> > ov = i.overlap (j);
+			if (ov) {
+				if (*ov == i) {
+					/* A contains all of B */
+					if (i.from != j.from) {
+						new_result.push_back (TimePeriod<T> (j.from, i.from));
+					}
+					if (i.to != j.to) {
+						new_result.push_back (TimePeriod<T> (i.to, j.to));
+					}
+				} else if (*ov == j) {
+					/* B contains all of A */
+				} else if (i.from < j.from) {
+					/* B overlaps start of A */
+					new_result.push_back (TimePeriod<T> (i.to, j.to));
+				} else if (i.to > j.to) {
+					/* B overlaps end of A */
+					new_result.push_back (TimePeriod<T> (j.from, i.from));
+				}
+			} else {
+				new_result.push_back (j);
+			}
+		}
+		result = new_result;
+	}
+
+	return result;
+}
+
 typedef TimePeriod<ContentTime> ContentTimePeriod;
 typedef TimePeriod<DCPTime> DCPTimePeriod;