Remove PositionChanged in favour of consumers having their own GUI-thread timers.
[dcpomatic.git] / src / wx / timeline.cc
index 30a5ef1724e9be5d23171de0a92f43ac405f847b..9f71847f5c626dfb7e39690c91010e19d4f54252 100644 (file)
 #include "timeline_labels_view.h"
 #include "timeline_video_content_view.h"
 #include "timeline_audio_content_view.h"
-#include "timeline_subtitle_content_view.h"
+#include "timeline_text_content_view.h"
 #include "timeline_atmos_content_view.h"
 #include "content_panel.h"
 #include "wx_util.h"
+#include "film_viewer.h"
 #include "lib/film.h"
 #include "lib/playlist.h"
 #include "lib/image_content.h"
 #include "lib/timer.h"
 #include "lib/audio_content.h"
-#include "lib/subtitle_content.h"
+#include "lib/text_content.h"
 #include "lib/video_content.h"
 #include "lib/atmos_mxf_content.h"
 #include <wx/graphics.h>
 #include <boost/weak_ptr.hpp>
 #include <boost/foreach.hpp>
 #include <list>
+#include <iterator>
 #include <iostream>
 
 using std::list;
 using std::cout;
 using std::min;
 using std::max;
+using std::abs;
 using boost::shared_ptr;
 using boost::weak_ptr;
 using boost::dynamic_pointer_cast;
 using boost::bind;
 using boost::optional;
+using namespace dcpomatic;
 
-Timeline::Timeline (wxWindow* parent, ContentPanel* cp, shared_ptr<Film> film)
+/* 3 hours in 640 pixels */
+double const Timeline::_minimum_pixels_per_second = 640.0 / (60 * 60 * 3);
+int const Timeline::_minimum_pixels_per_track = 16;
+
+Timeline::Timeline (wxWindow* parent, ContentPanel* cp, shared_ptr<Film> film, weak_ptr<FilmViewer> viewer)
        : wxPanel (parent, wxID_ANY)
-       , _labels_panel (new wxPanel (this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE))
+       , _labels_canvas (new wxScrolledCanvas (this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE))
        , _main_canvas (new wxScrolledCanvas (this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxFULL_REPAINT_ON_RESIZE))
        , _content_panel (cp)
        , _film (film)
+       , _viewer (viewer)
        , _time_axis_view (new TimelineTimeAxisView (*this, 64))
        , _reels_view (new TimelineReelsView (*this, 32))
        , _labels_view (new TimelineLabelsView (*this))
@@ -71,49 +80,76 @@ Timeline::Timeline (wxWindow* parent, ContentPanel* cp, shared_ptr<Film> film)
        , _tool (SELECT)
        , _x_scroll_rate (16)
        , _y_scroll_rate (16)
+       , _pixels_per_track (48)
+       , _first_resize (true)
+       , _timer (this)
 {
 #ifndef __WXOSX__
-       _labels_panel->SetDoubleBuffered (true);
+       _labels_canvas->SetDoubleBuffered (true);
        _main_canvas->SetDoubleBuffered (true);
 #endif
 
        wxSizer* sizer = new wxBoxSizer (wxHORIZONTAL);
-       sizer->Add (_labels_panel, 0, wxEXPAND);
-       _labels_panel->SetMinSize (wxSize (_labels_view->bbox().width, -1));
+       sizer->Add (_labels_canvas, 0, wxEXPAND);
+       _labels_canvas->SetMinSize (wxSize (_labels_view->bbox().width, -1));
        sizer->Add (_main_canvas, 1, wxEXPAND);
        SetSizer (sizer);
 
-       _labels_panel->Bind (wxEVT_PAINT,      boost::bind (&Timeline::paint_labels, this));
-       _main_canvas->Bind  (wxEVT_PAINT,      boost::bind (&Timeline::paint_main,   this));
-       _main_canvas->Bind  (wxEVT_LEFT_DOWN,  boost::bind (&Timeline::left_down,    this, _1));
-       _main_canvas->Bind  (wxEVT_LEFT_UP,    boost::bind (&Timeline::left_up,      this, _1));
-       _main_canvas->Bind  (wxEVT_RIGHT_DOWN, boost::bind (&Timeline::right_down,   this, _1));
-       _main_canvas->Bind  (wxEVT_MOTION,     boost::bind (&Timeline::mouse_moved,  this, _1));
-       _main_canvas->Bind  (wxEVT_SIZE,       boost::bind (&Timeline::resized,      this));
+       _labels_canvas->Bind (wxEVT_PAINT,      boost::bind (&Timeline::paint_labels, this));
+       _main_canvas->Bind   (wxEVT_PAINT,      boost::bind (&Timeline::paint_main,   this));
+       _main_canvas->Bind   (wxEVT_LEFT_DOWN,  boost::bind (&Timeline::left_down,    this, _1));
+       _main_canvas->Bind   (wxEVT_LEFT_UP,    boost::bind (&Timeline::left_up,      this, _1));
+       _main_canvas->Bind   (wxEVT_RIGHT_DOWN, boost::bind (&Timeline::right_down,   this, _1));
+       _main_canvas->Bind   (wxEVT_MOTION,     boost::bind (&Timeline::mouse_moved,  this, _1));
+       _main_canvas->Bind   (wxEVT_SIZE,       boost::bind (&Timeline::resized,      this));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_TOP,        boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_BOTTOM,     boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_LINEUP,     boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_LINEDOWN,   boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_PAGEUP,     boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_PAGEDOWN,   boost::bind (&Timeline::scrolled,     this, _1));
+       _main_canvas->Bind   (wxEVT_SCROLLWIN_THUMBTRACK, boost::bind (&Timeline::scrolled,     this, _1));
 
-       film_changed (Film::CONTENT);
+       film_change (CHANGE_TYPE_DONE, Film::CONTENT);
 
-       SetMinSize (wxSize (640, 4 * track_height() + 96));
+       SetMinSize (wxSize (640, 4 * pixels_per_track() + 96));
 
-       _film_changed_connection = film->Changed.connect (bind (&Timeline::film_changed, this, _1));
-       _film_content_changed_connection = film->ContentChanged.connect (bind (&Timeline::film_content_changed, this, _2, _3));
+       _film_changed_connection = film->Change.connect (bind (&Timeline::film_change, this, _1, _2));
+       _film_content_change_connection = film->ContentChange.connect (bind (&Timeline::film_content_change, this, _1, _3, _4));
 
-       _pixels_per_second = max (0.01, static_cast<double>(640) / film->length().seconds ());
+       Bind (wxEVT_TIMER, boost::bind(&Timeline::update_playhead, this));
+       _timer.Start (200, wxTIMER_CONTINUOUS);
 
        setup_scrollbars ();
-       _main_canvas->EnableScrolling (true, true);
+       _labels_canvas->ShowScrollbars (wxSHOW_SB_NEVER, wxSHOW_SB_NEVER);
+}
+
+void
+Timeline::update_playhead ()
+{
+       Refresh ();
+}
+
+void
+Timeline::set_pixels_per_second (double pps)
+{
+       _pixels_per_second = max (_minimum_pixels_per_second, pps);
 }
 
 void
 Timeline::paint_labels ()
 {
-       wxPaintDC dc (_labels_panel);
+       wxPaintDC dc (_labels_canvas);
 
        wxGraphicsContext* gc = wxGraphicsContext::Create (dc);
        if (!gc) {
                return;
        }
 
+       int vsx, vsy;
+       _labels_canvas->GetViewStart (&vsx, &vsy);
+       gc->Translate (-vsx * _x_scroll_rate, -vsy * _y_scroll_rate + tracks_y_offset());
+
        _labels_view->paint (gc, list<dcpomatic::Rect<int> >());
 
        delete gc;
@@ -166,17 +202,33 @@ Timeline::paint_main ()
                gc->DrawRectangle (
                        min (_down_point.x, _zoom_point->x),
                        min (_down_point.y, _zoom_point->y),
-                       fabs (_down_point.x - _zoom_point->x),
-                       fabs (_down_point.y - _zoom_point->y)
+                       abs (_down_point.x - _zoom_point->x),
+                       abs (_down_point.y - _zoom_point->y)
                        );
        }
 
+       /* Playhead */
+
+       shared_ptr<FilmViewer> vp = _viewer.lock ();
+       DCPOMATIC_ASSERT (vp);
+
+       gc->SetPen (*wxRED_PEN);
+       wxGraphicsPath path = gc->CreatePath ();
+       double const ph = vp->position().seconds() * pixels_per_second().get_value_or(0);
+       path.MoveToPoint (ph, 0);
+       path.AddLineToPoint (ph, pixels_per_track() * _tracks + 32);
+       gc->StrokePath (path);
+
        delete gc;
 }
 
 void
-Timeline::film_changed (Film::Property p)
+Timeline::film_change (ChangeType type, Film::Property p)
 {
+       if (type != CHANGE_TYPE_DONE) {
+               return;
+       }
+
        if (p == Film::CONTENT || p == Film::REEL_TYPE || p == Film::REEL_LENGTH) {
                ensure_ui_thread ();
                recreate_views ();
@@ -206,8 +258,8 @@ Timeline::recreate_views ()
                        _views.push_back (shared_ptr<TimelineView> (new TimelineAudioContentView (*this, i)));
                }
 
-               if (i->subtitle) {
-                       _views.push_back (shared_ptr<TimelineView> (new TimelineSubtitleContentView (*this, i)));
+               BOOST_FOREACH (shared_ptr<TextContent> j, i->text) {
+                       _views.push_back (shared_ptr<TimelineView> (new TimelineTextContentView (*this, i, j)));
                }
 
                if (dynamic_pointer_cast<AtmosMXFContent> (i)) {
@@ -221,12 +273,18 @@ Timeline::recreate_views ()
 }
 
 void
-Timeline::film_content_changed (int property, bool frequent)
+Timeline::film_content_change (ChangeType type, int property, bool frequent)
 {
+       if (type != CHANGE_TYPE_DONE) {
+               return;
+       }
+
        ensure_ui_thread ();
 
-       if (property == AudioContentProperty::STREAMS) {
+       if (property == AudioContentProperty::STREAMS || property == VideoContentProperty::FRAME_TYPE) {
                recreate_views ();
+       } else if (property == ContentProperty::POSITION || property == ContentProperty::LENGTH) {
+               _reels_view->force_redraw ();
        } else if (!frequent) {
                setup_scrollbars ();
                Refresh ();
@@ -235,7 +293,7 @@ Timeline::film_content_changed (int property, bool frequent)
 
 template <class T>
 int
-place (TimelineViewList& views, int& tracks)
+place (shared_ptr<const Film> film, TimelineViewList& views, int& tracks)
 {
        int const base = tracks;
 
@@ -249,7 +307,7 @@ place (TimelineViewList& views, int& tracks)
                int t = base;
 
                shared_ptr<Content> content = cv->content();
-               DCPTimePeriod const content_period (content->position(), content->end());
+               DCPTimePeriod const content_period (content->position(), content->end(film));
 
                while (true) {
                        TimelineViewList::iterator j = views.begin();
@@ -263,7 +321,7 @@ place (TimelineViewList& views, int& tracks)
                                shared_ptr<Content> test_content = test->content();
                                if (
                                        test->track() && test->track().get() == t &&
-                                       content_period.overlap(DCPTimePeriod(test_content->position(), test_content->end()))) {
+                                       content_period.overlap(DCPTimePeriod(test_content->position(), test_content->end(film)))) {
                                        /* we have an overlap on track `t' */
                                        ++t;
                                        break;
@@ -285,21 +343,45 @@ place (TimelineViewList& views, int& tracks)
        return tracks - base;
 }
 
+/** Compare the mapped output channels of two TimelineViews, so we can into
+ *  order of first mapped DCP channel.
+ */
+struct AudioMappingComparator {
+       bool operator()(shared_ptr<TimelineView> a, shared_ptr<TimelineView> b) {
+               int la = -1;
+               shared_ptr<TimelineAudioContentView> cva = dynamic_pointer_cast<TimelineAudioContentView>(a);
+               if (cva) {
+                       list<int> oc = cva->content()->audio->mapping().mapped_output_channels();
+                       la = *min_element(boost::begin(oc), boost::end(oc));
+               }
+               int lb = -1;
+               shared_ptr<TimelineAudioContentView> cvb = dynamic_pointer_cast<TimelineAudioContentView>(b);
+               if (cvb) {
+                       list<int> oc = cvb->content()->audio->mapping().mapped_output_channels();
+                       lb = *min_element(boost::begin(oc), boost::end(oc));
+               }
+               return la < lb;
+       }
+};
+
 void
 Timeline::assign_tracks ()
 {
        /* Tracks are:
           Video (mono or left-eye)
           Video (right-eye)
-          Subtitle 1
-          Subtitle 2
-          Subtitle N
+          Text 1
+          Text 2
+          Text N
           Atmos
           Audio 1
           Audio 2
           Audio N
        */
 
+       shared_ptr<const Film> film = _film.lock ();
+       DCPOMATIC_ASSERT (film);
+
        _tracks = 0;
 
        for (TimelineViewList::iterator i = _views.begin(); i != _views.end(); ++i) {
@@ -330,9 +412,9 @@ Timeline::assign_tracks ()
 
        _tracks = max (_tracks, 1);
 
-       /* Subtitle */
+       /* Texts */
 
-       int const subtitle_tracks = place<TimelineSubtitleContentView> (_views, _tracks);
+       int const text_tracks = place<TimelineTextContentView> (film, _views, _tracks);
 
        /* Atmos */
 
@@ -352,15 +434,20 @@ Timeline::assign_tracks ()
                ++_tracks;
        }
 
-       /* Audio */
+       /* Audio.  We're sorting the views so that we get the audio views in order of increasing
+          DCP channel index.
+       */
 
-       place<TimelineAudioContentView> (_views, _tracks);
+       TimelineViewList views = _views;
+       sort(views.begin(), views.end(), AudioMappingComparator());
+       int const audio_tracks = place<TimelineAudioContentView> (film, views, _tracks);
 
        _labels_view->set_3d (have_3d);
-       _labels_view->set_subtitle_tracks (subtitle_tracks);
+       _labels_view->set_audio_tracks (audio_tracks);
+       _labels_view->set_text_tracks (text_tracks);
        _labels_view->set_atmos (have_atmos);
 
-       _time_axis_view->set_y (tracks() * track_height() + 64);
+       _time_axis_view->set_y (tracks());
        _reels_view->set_y (8);
 }
 
@@ -377,7 +464,12 @@ Timeline::setup_scrollbars ()
        if (!film || !_pixels_per_second) {
                return;
        }
-       _main_canvas->SetVirtualSize (*_pixels_per_second * film->length().seconds(), tracks() * track_height() + 96);
+
+       int const h = tracks() * pixels_per_track() + tracks_y_offset() + _time_axis_view->bbox().height;
+
+       _labels_canvas->SetVirtualSize (_labels_view->bbox().width, h);
+       _labels_canvas->SetScrollRate (_x_scroll_rate, _y_scroll_rate);
+       _main_canvas->SetVirtualSize (*_pixels_per_second * film->length().seconds(), h);
        _main_canvas->SetScrollRate (_x_scroll_rate, _y_scroll_rate);
 }
 
@@ -386,7 +478,11 @@ Timeline::event_to_view (wxMouseEvent& ev)
 {
        /* Search backwards through views so that we find the uppermost one first */
        TimelineViewList::reverse_iterator i = _views.rbegin();
-       Position<int> const p (ev.GetX(), ev.GetY());
+
+       int vsx, vsy;
+       _main_canvas->GetViewStart (&vsx, &vsy);
+       Position<int> const p (ev.GetX() + vsx * _x_scroll_rate, ev.GetY() + vsy * _y_scroll_rate);
+
        while (i != _views.rend() && !(*i)->bbox().contains (p)) {
                shared_ptr<TimelineContentView> cv = dynamic_pointer_cast<TimelineContentView> (*i);
                ++i;
@@ -410,6 +506,9 @@ Timeline::left_down (wxMouseEvent& ev)
                left_down_select (ev);
                break;
        case ZOOM:
+       case ZOOM_ALL:
+       case SNAP:
+       case SEQUENCE:
                /* Nothing to do */
                break;
        }
@@ -453,12 +552,15 @@ Timeline::left_down_select (wxMouseEvent& ev)
                                continue;
                        }
 
+                       shared_ptr<Film> film = _film.lock ();
+                       DCPOMATIC_ASSERT (film);
+
                        _start_snaps.push_back (cv->content()->position());
                        _end_snaps.push_back (cv->content()->position());
-                       _start_snaps.push_back (cv->content()->end());
-                       _end_snaps.push_back (cv->content()->end());
+                       _start_snaps.push_back (cv->content()->end(film));
+                       _end_snaps.push_back (cv->content()->end(film));
 
-                       BOOST_FOREACH (DCPTime i, cv->content()->reel_split_points()) {
+                       BOOST_FOREACH (DCPTime i, cv->content()->reel_split_points(film)) {
                                _start_snaps.push_back (i);
                        }
                }
@@ -480,6 +582,10 @@ Timeline::left_up (wxMouseEvent& ev)
        case ZOOM:
                left_up_zoom (ev);
                break;
+       case ZOOM_ALL:
+       case SNAP:
+       case SEQUENCE:
+               break;
        }
 }
 
@@ -491,7 +597,12 @@ Timeline::left_up_select (wxMouseEvent& ev)
        }
 
        _content_panel->set_selection (selected_content ());
-       set_position_from_event (ev);
+       /* Since we may have just set change signals back to `not-frequent', we have to
+          make sure this position change is signalled, even if the position value has
+          not changed since the last time it was set (with frequent=true).  This is
+          a bit of a hack.
+       */
+       set_position_from_event (ev, true);
 
        /* Clear up up the stuff we don't do during drag */
        assign_tracks ();
@@ -513,16 +624,34 @@ Timeline::left_up_zoom (wxMouseEvent& ev)
        wxPoint top_left(min(_down_point.x, _zoom_point->x), min(_down_point.y, _zoom_point->y));
        wxPoint bottom_right(max(_down_point.x, _zoom_point->x), max(_down_point.y, _zoom_point->y));
 
-       DCPTime time_left = DCPTime::from_seconds((top_left.x + vsx) / *_pixels_per_second);
-       DCPTime time_right = DCPTime::from_seconds((bottom_right.x + vsx) / *_pixels_per_second);
-       _pixels_per_second = GetSize().GetWidth() / (time_right.seconds() - time_left.seconds());
+       if ((bottom_right.x - top_left.x) < 8 || (bottom_right.y - top_left.y) < 8) {
+               /* Very small zoom rectangle: we assume it wasn't intentional */
+               return;
+       }
+
+       DCPTime const time_left = DCPTime::from_seconds((top_left.x + vsx) / *_pixels_per_second);
+       DCPTime const time_right = DCPTime::from_seconds((bottom_right.x + vsx) / *_pixels_per_second);
+       set_pixels_per_second (double(GetSize().GetWidth()) / (time_right.seconds() - time_left.seconds()));
+
+       double const tracks_top = double(top_left.y - tracks_y_offset()) / _pixels_per_track;
+       double const tracks_bottom = double(bottom_right.y - tracks_y_offset()) / _pixels_per_track;
+       set_pixels_per_track (lrint(GetSize().GetHeight() / (tracks_bottom - tracks_top)));
+
        setup_scrollbars ();
-       _main_canvas->Scroll (time_left.seconds() * *_pixels_per_second / _x_scroll_rate, wxDefaultCoord);
+       int const y = (tracks_top * _pixels_per_track + tracks_y_offset()) / _y_scroll_rate;
+       _main_canvas->Scroll (time_left.seconds() * *_pixels_per_second / _x_scroll_rate, y);
+       _labels_canvas->Scroll (0, y);
 
        _zoom_point = optional<wxPoint> ();
        Refresh ();
 }
 
+void
+Timeline::set_pixels_per_track (int h)
+{
+       _pixels_per_track = max(_minimum_pixels_per_track, h);
+}
+
 void
 Timeline::mouse_moved (wxMouseEvent& ev)
 {
@@ -533,6 +662,10 @@ Timeline::mouse_moved (wxMouseEvent& ev)
        case ZOOM:
                mouse_moved_zoom (ev);
                break;
+       case ZOOM_ALL:
+       case SNAP:
+       case SEQUENCE:
+               break;
        }
 }
 
@@ -566,8 +699,14 @@ Timeline::right_down (wxMouseEvent& ev)
                break;
        case ZOOM:
                /* Zoom out */
-               _pixels_per_second = *_pixels_per_second / 2;
+               set_pixels_per_second (*_pixels_per_second / 2);
+               set_pixels_per_track (_pixels_per_track / 2);
                setup_scrollbars ();
+               Refresh ();
+               break;
+       case ZOOM_ALL:
+       case SNAP:
+       case SEQUENCE:
                break;
        }
 }
@@ -599,7 +738,7 @@ Timeline::maybe_snap (DCPTime a, DCPTime b, optional<DCPTime>& nearest_distance)
 }
 
 void
-Timeline::set_position_from_event (wxMouseEvent& ev)
+Timeline::set_position_from_event (wxMouseEvent& ev, bool force_emit)
 {
        if (!_pixels_per_second) {
                return;
@@ -626,9 +765,11 @@ Timeline::set_position_from_event (wxMouseEvent& ev)
 
        DCPTime new_position = _down_view_position + DCPTime::from_seconds ((p.x - _down_point.x) / pps);
 
-       if (_snap) {
+       shared_ptr<Film> film = _film.lock ();
+       DCPOMATIC_ASSERT (film);
 
-               DCPTime const new_end = new_position + _down_view->content()->length_after_trim();
+       if (_snap) {
+               DCPTime const new_end = new_position + _down_view->content()->length_after_trim(film);
                /* Signed `distance' to nearest thing (i.e. negative is left on the timeline,
                   positive is right).
                */
@@ -656,17 +797,15 @@ Timeline::set_position_from_event (wxMouseEvent& ev)
                new_position = DCPTime ();
        }
 
-       _down_view->content()->set_position (new_position);
+       _down_view->content()->set_position (film, new_position, force_emit);
 
-       shared_ptr<Film> film = _film.lock ();
-       DCPOMATIC_ASSERT (film);
        film->set_sequence (false);
 }
 
 void
 Timeline::force_redraw (dcpomatic::Rect<int> const & r)
 {
-       RefreshRect (wxRect (r.x, r.y, r.width, r.height), false);
+       _main_canvas->RefreshRect (wxRect (r.x, r.y, r.width, r.height), false);
 }
 
 shared_ptr<const Film>
@@ -678,6 +817,10 @@ Timeline::film () const
 void
 Timeline::resized ()
 {
+       if (_main_canvas->GetSize().GetWidth() > 0 && _first_resize) {
+               zoom_all ();
+               _first_resize = false;
+       }
        setup_scrollbars ();
 }
 
@@ -730,3 +873,56 @@ Timeline::set_selection (ContentList selection)
                }
        }
 }
+
+int
+Timeline::tracks_y_offset () const
+{
+       return _reels_view->bbox().height + 4;
+}
+
+int
+Timeline::width () const
+{
+       return _main_canvas->GetVirtualSize().GetWidth();
+}
+
+void
+Timeline::scrolled (wxScrollWinEvent& ev)
+{
+       if (ev.GetOrientation() == wxVERTICAL) {
+               int x, y;
+               _main_canvas->GetViewStart (&x, &y);
+               _labels_canvas->Scroll (0, y);
+       }
+       ev.Skip ();
+}
+
+void
+Timeline::tool_clicked (Tool t)
+{
+       switch (t) {
+       case ZOOM:
+       case SELECT:
+               _tool = t;
+               break;
+       case ZOOM_ALL:
+               zoom_all ();
+               break;
+       case SNAP:
+       case SEQUENCE:
+               break;
+       }
+}
+
+void
+Timeline::zoom_all ()
+{
+       shared_ptr<Film> film = _film.lock ();
+       DCPOMATIC_ASSERT (film);
+       set_pixels_per_second ((_main_canvas->GetSize().GetWidth() - 32) / film->length().seconds());
+       set_pixels_per_track ((_main_canvas->GetSize().GetHeight() - tracks_y_offset() - _time_axis_view->bbox().height - 32) / _tracks);
+       setup_scrollbars ();
+       _main_canvas->Scroll (0, 0);
+       _labels_canvas->Scroll (0, 0);
+       Refresh ();
+}