+ template <class T>
+ class Last
+ {
+ public:
+ void set_next (T const& next) {
+ _next = next;
+ }
+
+ bool changed () const {
+ return !_value || *_value != _next;
+ }
+
+ void update () {
+ _value = _next;
+ }
+
+ private:
+ boost::optional<T> _value;
+ T _next;
+ };
+
+ Last<wxSize> _last_canvas_size;
+ Last<dcp::Size> _last_video_size;
+ Last<Position<int>> _last_inter_position;
+ Last<dcp::Size> _last_inter_size;
+ Last<dcp::Size> _last_out_size;
+ Last<boost::optional<dcpomatic::Rect<float>>> _last_crop_guess;
+