Add another makeLoopingAudioStream factory for transparently looping a certain interval of a SeekableAudioStream.

svn-id: r47159

2 files changed, 35 insertions, 0 deletions

diff --git a/sound/audiostream.cpp b/sound/audiostream.cpp
index f16011ce52..ea71c161e8 100644
--- a/sound/audiostream.cpp
+++ b/sound/audiostream.cpp
@@ -144,6 +144,22 @@ AudioStream *makeLoopingAudioStream(RewindableAudioStream *stream, uint loops) {
 		return stream;
 }
 
+AudioStream *makeLoopingAudioStream(SeekableAudioStream *stream, Timestamp start, Timestamp end, uint loops) {
+	if (!start.totalNumberOfFrames() && (!end.totalNumberOfFrames() || end == stream->getLength())) {
+		return makeLoopingAudioStream(stream, loops);
+	} else {
+		if (!end.totalNumberOfFrames())
+			end = stream->getLength();
+
+		if (start > end) {
+			delete stream;
+			return 0;
+		}
+
+		return makeLoopingAudioStream(new SubSeekableAudioStream(stream, start, end), loops);
+	}
+}
+
 #pragma mark -
 #pragma mark --- SubSeekableAudioStream ---
 #pragma mark -
diff --git a/sound/audiostream.h b/sound/audiostream.h
index 85807e8134..e418c2d524 100644
--- a/sound/audiostream.h
+++ b/sound/audiostream.h
@@ -197,6 +197,25 @@ public:
 };
 
 /**
+ * Wrapper functionallity to efficiently create a stream, which might be looped
+ * in a certain interval.
+ *
+ * This automatically starts the stream at time "start"!
+ *
+ * Note that this function does not return a LoopingAudioStream, because it does
+ * not create one, when the loop count is "1". This allows to keep the runtime
+ * overhead down, when the code does not require any functionallity only offered
+ * by LoopingAudioStream.
+ *
+ * @param stream Stream to loop (will be automatically destroyed, when the looping is done)
+ * @param start Starttime of the stream interval to be looped
+ * @param end End of the stream interval to be looped (a zero time, means till end)
+ * @param loops How often to loop (0 = infinite)
+ * @return A new AudioStream, which offers the desired functionallity.
+ */
+AudioStream *makeLoopingAudioStream(SeekableAudioStream *stream, Timestamp start, Timestamp end, uint loops);
+
+/**
  * A SubSeekableAudioStream provides access to a SeekableAudioStream
  * just in the range [start, end).
  * The same caveats apply to SubSeekableAudioStream as do to SeekableAudioStream.