Basic snapping in the timeline.

[dcpomatic.git] / src / wx / timeline.cc

diff --git a/src/wx/timeline.cc b/src/wx/timeline.cc
index 87070b35edb485d0003f5a971590d349a38a87e3..1f0aee4e8528be86bf5020a760532ed98be85882 100644 (file)
--- a/src/wx/timeline.cc
+++ b/src/wx/timeline.cc
@@ -33,7 +33,9 @@ using boost::shared_ptr;
 using boost::weak_ptr;
 using boost::dynamic_pointer_cast;
 using boost::bind;
+using boost::optional;
 
+/** Parent class for components of the timeline (e.g. a piece of content or an axis) */
 class View : public boost::noncopyable
 {
 public:
@@ -332,6 +334,7 @@ Timeline::Timeline (wxWindow* parent, FilmEditor* ed, shared_ptr<Film> film)
        , _down_view_position (0)
        , _first_move (false)
        , _menu (film, this)
+       , _snap (true)
 {
 #ifndef __WXOSX__
        SetDoubleBuffered (true);
@@ -577,6 +580,9 @@ Timeline::set_position_from_event (wxMouseEvent& ev)
        wxPoint const p = ev.GetPosition();
 
        if (!_first_move) {
+               /* We haven't moved yet; in that case, we must move the mouse some reasonable distance
+                  before the drag is considered to have started.
+               */
                int const dist = sqrt (pow (p.x - _down_point.x, 2) + pow (p.y - _down_point.y, 2));
                if (dist < 8) {
                        return;
@@ -584,9 +590,56 @@ Timeline::set_position_from_event (wxMouseEvent& ev)
                _first_move = true;
        }
 
-       Time const time_diff = (p.x - _down_point.x) / _pixels_per_time_unit;
        if (_down_view) {
-               _down_view->content()->set_position (max (static_cast<Time> (0), _down_view_position + time_diff));
+               Time new_position = _down_view_position + (p.x - _down_point.x) / _pixels_per_time_unit;
+               
+               if (_snap) {
+
+                       bool first = true;
+                       Time nearest_distance = TIME_MAX;
+                       Time nearest_new_position = TIME_MAX;
+                       
+                       /* Find the nearest content edge; this is inefficient */
+                       for (ViewList::iterator i = _views.begin(); i != _views.end(); ++i) {
+                               shared_ptr<ContentView> cv = dynamic_pointer_cast<ContentView> (*i);
+                               if (!cv || cv == _down_view) {
+                                       continue;
+                               }
+
+                               {
+                                       /* Snap starts to ends */
+                                       Time const d = abs (cv->content()->end() - new_position);
+                                       if (first || d < nearest_distance) {
+                                               nearest_distance = d;
+                                               nearest_new_position = cv->content()->end();
+                                       }
+                               }
+
+                               {
+                                       /* Snap ends to starts */
+                                       Time const d = abs (cv->content()->position() - (new_position + _down_view->content()->length_after_trim()));
+                                       if (d < nearest_distance) {
+                                               nearest_distance = d;
+                                               nearest_new_position = cv->content()->position() - _down_view->content()->length_after_trim ();
+                                       }
+                               }
+
+                               first = false;
+                       }
+
+                       if (!first) {
+                               /* Snap if it's close; `close' means within a proportion of the time on the timeline */
+                               if (nearest_distance < (width() / pixels_per_time_unit()) / 32) {
+                                       new_position = nearest_new_position;
+                               }
+                       }
+               }
+               
+               if (new_position < 0) {
+                       new_position = 0;
+               }
+       
+               _down_view->content()->set_position (new_position);
 
                shared_ptr<Film> film = _film.lock ();
                assert (film);