Optimise the feel of some GUI functions by doing the seek after

many content changes in an idle handler, rather than blocking
the UI update until the seek and image redisplay have finished.

3 files changed, 8 insertions, 4 deletions

diff --git a/src/lib/butler.cc b/src/lib/butler.cc
index 8c46d5190..2d6c46c7e 100644
--- a/src/lib/butler.cc
+++ b/src/lib/butler.cc
@@ -216,12 +216,16 @@ try
 	_arrived.notify_all ();
 }
 
+/** @param blocking true if we should block until video is available.  If blocking is false
+ *  and no video is immediately available the method will return a 0 PlayerVideo and the error AGAIN.
+ *  @param e if non-0 this is filled with an error code (if an error occurs) or is untouched if no error occurs.
+ */
 pair<shared_ptr<PlayerVideo>, DCPTime>
-Butler::get_video (Error* e)
+Butler::get_video (bool blocking, Error* e)
 {
 	boost::mutex::scoped_lock lm (_mutex);
 
-	if (_suspended) {
+	if (_suspended || (_video.empty() && !blocking)) {
 		if (e) {
 			*e = AGAIN;
 		}
diff --git a/src/lib/butler.h b/src/lib/butler.h
index 09c182f9c..e5581ccb4 100644
--- a/src/lib/butler.h
+++ b/src/lib/butler.h
@@ -54,7 +54,7 @@ public:
 		AGAIN
 	};
 
-	std::pair<boost::shared_ptr<PlayerVideo>, dcpomatic::DCPTime> get_video (Error* e = 0);
+	std::pair<boost::shared_ptr<PlayerVideo>, dcpomatic::DCPTime> get_video (bool blocking, Error* e = 0);
 	boost::optional<dcpomatic::DCPTime> get_audio (float* out, Frame frames);
 	boost::optional<TextRingBuffers::Data> get_closed_caption ();
 
diff --git a/src/lib/ffmpeg_encoder.cc b/src/lib/ffmpeg_encoder.cc
index 7c641f5ab..572e7ae16 100644
--- a/src/lib/ffmpeg_encoder.cc
+++ b/src/lib/ffmpeg_encoder.cc
@@ -150,7 +150,7 @@ FFmpegEncoder::go ()
 		}
 
 		for (int j = 0; j < gets_per_frame; ++j) {
-			pair<shared_ptr<PlayerVideo>, DCPTime> v = _butler->get_video ();
+			pair<shared_ptr<PlayerVideo>, DCPTime> v = _butler->get_video (true, 0);
 			encoder->get(v.first->eyes())->video(v.first, v.second);
 		}