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.

6 files changed, 32 insertions, 7 deletions

diff --git a/src/tools/dcpomatic.cc b/src/tools/dcpomatic.cc
index 78fce27f2..8677acc18 100644
--- a/src/tools/dcpomatic.cc
+++ b/src/tools/dcpomatic.cc
@@ -408,6 +408,12 @@ public:
 		add_accelerators ();
 	}
 
+	~DOMFrame()
+	{
+		/* This holds a reference to FilmViewer, so get rid of it first */
+		_video_waveform_dialog.reset();
+	}
+
 	void add_accelerators ()
 	{
 #ifdef __WXOSX__
diff --git a/src/wx/content_menu.cc b/src/wx/content_menu.cc
index 62421a20b..559b57553 100644
--- a/src/wx/content_menu.cc
+++ b/src/wx/content_menu.cc
@@ -586,7 +586,7 @@ ContentMenu::auto_crop ()
 	});
 
 	/* Also update the dialog and view when we're looking at a different frame */
-	_auto_crop_viewer_connection = _viewer.ImageChanged.connect([this, guess_crop_for_content, update_viewer](shared_ptr<PlayerVideo>) {
+	_auto_crop_viewer_connection = _viewer.ImageChanged.connect([this, guess_crop_for_content, update_viewer]() {
 		auto const crop = guess_crop_for_content();
 		_auto_crop_dialog->set(crop);
 		update_viewer(crop);
diff --git a/src/wx/film_viewer.cc b/src/wx/film_viewer.cc
index 957407338..0efa75380 100644
--- a/src/wx/film_viewer.cc
+++ b/src/wx/film_viewer.cc
@@ -864,7 +864,15 @@ FilmViewer::gets () const
 void
 FilmViewer::image_changed (shared_ptr<PlayerVideo> pv)
 {
-	emit (boost::bind(boost::ref(ImageChanged), pv));
+	_last_image = pv;
+	emit(boost::bind(boost::ref(ImageChanged)));
+}
+
+
+shared_ptr<const PlayerVideo>
+FilmViewer::last_image() const
+{
+	return _last_image;
 }
 
 
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;
 };
diff --git a/src/wx/video_waveform_plot.cc b/src/wx/video_waveform_plot.cc
index ebff68096..2827689a7 100644
--- a/src/wx/video_waveform_plot.cc
+++ b/src/wx/video_waveform_plot.cc
@@ -56,12 +56,13 @@ int const VideoWaveformPlot::_x_axis_width = 52;
 VideoWaveformPlot::VideoWaveformPlot(wxWindow* parent, weak_ptr<const Film> film, FilmViewer& viewer)
 	: wxPanel (parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE)
 	, _film (film)
+	, _viewer(viewer)
 {
 #ifndef __WXOSX__
 	SetDoubleBuffered (true);
 #endif
 
-	_viewer_connection = viewer.ImageChanged.connect(boost::bind(&VideoWaveformPlot::set_image, this, _1));
+	_viewer_connection = _viewer.ImageChanged.connect(boost::bind(&VideoWaveformPlot::set_image, this));
 
 	Bind (wxEVT_PAINT, boost::bind(&VideoWaveformPlot::paint, this));
 	Bind (wxEVT_SIZE,  boost::bind(&VideoWaveformPlot::sized, this, _1));
@@ -186,7 +187,7 @@ VideoWaveformPlot::create_waveform ()
 
 
 void
-VideoWaveformPlot::set_image (shared_ptr<PlayerVideo> image)
+VideoWaveformPlot::set_image()
 {
 	if (!_enabled) {
 		return;
@@ -195,7 +196,7 @@ VideoWaveformPlot::set_image (shared_ptr<PlayerVideo> image)
 	/* We must copy the PlayerVideo here as we will call ::image() on it, potentially
 	   with a different pixel_format than was used when ::prepare() was called.
 	*/
-	_image = DCPVideo::convert_to_xyz(image->shallow_copy());
+	_image = DCPVideo::convert_to_xyz(_viewer.last_image()->shallow_copy());
 	_dirty = true;
 	Refresh ();
 }
diff --git a/src/wx/video_waveform_plot.h b/src/wx/video_waveform_plot.h
index f482da8f8..e6e7a6f3d 100644
--- a/src/wx/video_waveform_plot.h
+++ b/src/wx/video_waveform_plot.h
@@ -56,7 +56,7 @@ private:
 	void paint ();
 	void sized (wxSizeEvent &);
 	void create_waveform ();
-	void set_image (std::shared_ptr<PlayerVideo>);
+	void set_image();
 	void mouse_moved (wxMouseEvent &);
 
 	std::weak_ptr<const Film> _film;
@@ -67,6 +67,8 @@ private:
 	int _component = 0;
 	int _contrast = 0;
 
+	FilmViewer& _viewer;
+
 	static int const _vertical_margin;
 	static int const _pixel_values;
 	static int const _x_axis_width;