Don't bind a shared_ptr<PlayerVideo> to ImageChanged (#3013).

Otherwise if the GUI is busy when the emissions build up, each one holds
a reference to a potentially large image.

This caused enormous memory use when playing a DCP and verifying it at
the same time.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/wx/film_viewer.h b/src/wx/film_viewer.h
index 8f0cad545..c8aade6c0 100644
--- a/src/wx/film_viewer.h
+++ b/src/wx/film_viewer.h
@@ -155,7 +155,10 @@ public:
 
 	Frame average_latency() const;
 
-	boost::signals2::signal<void (std::shared_ptr<PlayerVideo>)> ImageChanged;
+	/** The image we are viewing changed: call last_image() to get the image */
+	boost::signals2::signal<void ()> ImageChanged;
+	std::shared_ptr<const PlayerVideo> last_image() const;
+
 	boost::signals2::signal<void ()> Started;
 	boost::signals2::signal<void ()> Stopped;
 	/** While playing back we reached the end of the film (emitted from GUI thread) */
@@ -222,5 +225,10 @@ private:
 
 	boost::optional<dcpomatic::Rect<float>> _crop_guess;
 
+	/** Keep track of the image that we were talking about with the last
+	 *  emission of ImageChanged.
+	 */
+	std::shared_ptr<const PlayerVideo> _last_image;
+
 	boost::signals2::scoped_connection _config_changed_connection;
 };