Only compute and render the visible portion of crossfades. Fixes #3498.

git-svn-id: svn://localhost/ardour2/branches/3.0@7901 d708f5d6-7413-0410-9779-e7cbd77b26cf

gtk2_ardour/audio_streamview.cc

@@ -826,3 +826,14 @@ AudioStreamView::parameter_changed (string const & p)
 		set_waveform_shape (Config->get_waveform_shape ());
 	}
 }
+
+void
+AudioStreamView::horizontal_position_changed ()
+{
+	/* we only `draw' the bit of the curve that is visible, so we need to update here */
+	
+	for (CrossfadeViewList::iterator i = crossfade_views.begin(); i != crossfade_views.end(); ++i) {
+		i->second->horizontal_position_changed ();
+	}
+}
+

gtk2_ardour/audio_streamview.h

@@ -57,6 +57,7 @@ class AudioStreamView : public StreamView
 	~AudioStreamView ();
 
 	int set_samples_per_unit (gdouble spp);
+	void horizontal_position_changed ();
 
 	int     set_amplitude_above_axis (gdouble app);
 	gdouble get_amplitude_above_axis () { return _amplitude_above_axis; }

gtk2_ardour/crossfade_view.cc

@@ -55,7 +55,8 @@ CrossfadeView::CrossfadeView (ArdourCanvas::Group *parent,
 			    xf->length(), false, false, TimeAxisViewItem::Visibility (TimeAxisViewItem::ShowFrame)),
 	  crossfade (xf),
 	  left_view (lview),
-	  right_view (rview)	
+	  right_view (rview),
+	  _all_in_view (false)
 {
 	_valid = true;
 	_visible = true;
@@ -144,13 +145,12 @@ CrossfadeView::crossfade_changed (const PropertyChange& what_changed)
 	}
 }
 
+/** Set up our fade_in and fade_out curves to contain points for the currently visible portion
+ *  of the crossfade.
+ */
 void
 CrossfadeView::redraw_curves ()
 {
-	Points* points;
-	int32_t npoints;
-	float* vec;
-
 	if (!crossfade->following_overlap()) {
 		/* curves should not be visible */
 		fade_in->hide ();
@@ -163,8 +163,21 @@ CrossfadeView::redraw_curves ()
 		return;
 	}
 
-	npoints = get_time_axis_view().editor().frame_to_pixel (crossfade->length());
+	PublicEditor& editor = get_time_axis_view().editor ();
-	// npoints = std::min (gdk_screen_width(), npoints);
+
+	framepos_t const editor_left = editor.leftmost_position ();
+	framepos_t const editor_right = editor_left + editor.current_page_frames ();
+	framepos_t const xfade_left = crossfade->position ();
+	framepos_t const xfade_right = xfade_left + crossfade->length ();
+
+	/* Work out the range of our frames that are visible */
+	framepos_t const min_frames = std::max (editor_left, xfade_left);
+	framepos_t const max_frames = std::min (editor_right, xfade_right);
+
+	_all_in_view = (editor_left <= xfade_left && editor_right >= xfade_right);
+
+	/* Hence the number of points that we will render */
+	int32_t const npoints = editor.frame_to_pixel (max_frames - min_frames);
 	
 	if (!_visible || !crossfade->active() || npoints < 3) {
 		fade_in->hide();
@@ -175,24 +188,30 @@ CrossfadeView::redraw_curves ()
 		fade_out->show();
 	}
 
-	points = get_canvas_points ("xfade edit redraw", npoints);
+	Points* points = get_canvas_points ("xfade edit redraw", npoints);
-	vec = new float[npoints];
+	float* vec = new float[npoints];
 
-	crossfade->fade_in().curve().get_vector (0, crossfade->length(), vec, npoints);
+	crossfade->fade_in().curve().get_vector (min_frames - crossfade->position(), max_frames - crossfade->position(), vec, npoints);
+
+	/* Work out the offset from the start of the crossfade to the visible part, in pixels */
+	double xoff = 0;
+	if (crossfade->position() < editor.leftmost_position()) {
+		xoff = editor.frame_to_pixel (min_frames) - editor.frame_to_pixel (crossfade->position ());
+	}
 
 	for (int i = 0, pci = 0; i < npoints; ++i) {
 		Art::Point &p = (*points)[pci++];
-		p.set_x (i + 1);
+		p.set_x (xoff + i + 1);
 		p.set_y (_height - ((_height - 2) * vec[i]));
 	}
 
 	fade_in->property_points() = *points;
 
-	crossfade->fade_out().curve().get_vector (0, crossfade->length(), vec, npoints);
+	crossfade->fade_out().curve().get_vector (min_frames - crossfade->position(), max_frames - crossfade->position(), vec, npoints);
 
 	for (int i = 0, pci = 0; i < npoints; ++i) {
 		Art::Point &p = (*points)[pci++];
-		p.set_x (i + 1);
+		p.set_x (xoff + i + 1);
 		p.set_y (_height - ((_height - 2) * vec[i]));
 	}
 	
@@ -269,3 +288,17 @@ CrossfadeView::crossfade_fades_changed ()
 {
 	redraw_curves ();
 }
+
+void
+CrossfadeView::horizontal_position_changed ()
+{
+	/* If the crossfade curves are entirely within the editor's visible space, there is
+	   no need to redraw them here as they will be completely drawn (as distinct from
+	   the other case where the horizontal position change will uncover `undrawn'
+	   sections).
+	*/
+	
+	if (!_all_in_view) {
+		redraw_curves ();
+	}
+}

gtk2_ardour/crossfade_view.h

@@ -59,6 +59,7 @@ struct CrossfadeView : public TimeAxisViewItem
     void fake_hide ();
     void hide ();
     void show ();
+    void horizontal_position_changed ();
 
   protected:
     void reset_width_dependent_items (double pixel_width);
@@ -66,6 +67,7 @@ struct CrossfadeView : public TimeAxisViewItem
   private:
     bool _valid;
     bool _visible;
+    bool _all_in_view;   
 
     ArdourCanvas::Line *fade_in;
     ArdourCanvas::Line *fade_out;

gtk2_ardour/editor.cc

@@ -4691,7 +4691,19 @@ Editor::idle_visual_changer ()
 	VisualChange::Type p = pending_visual_change.pending;
 	pending_visual_change.pending = (VisualChange::Type) 0;
 
-	double last_time_origin = horizontal_position ();
+	double const last_time_origin = horizontal_position ();
+
+	if (p & VisualChange::TimeOrigin) {
+		/* This is a bit of a hack, but set_frames_per_unit
+		   below will (if called) end up with the
+		   CrossfadeViews looking at Editor::leftmost_frame,
+		   and if we're changing origin and zoom in the same
+		   operation it will be the wrong value unless we
+		   update it here.
+		*/
+
+		leftmost_frame = pending_visual_change.time_origin;
+	}
 
 	if (p & VisualChange::ZoomLevel) {
 		set_frames_per_unit (pending_visual_change.frames_per_unit);

gtk2_ardour/editor_canvas.cc

@@ -792,6 +792,8 @@ Editor::set_horizontal_position (double p)
 		_summary->set_overlays_dirty ();
 	}
 
+	HorizontalPositionChanged (); /* EMIT SIGNAL */
+
 #ifndef GTKOSX
 	if (!autoscroll_active && !_stationary_playhead) {
 		/* force rulers and canvas to move in lock step */

gtk2_ardour/public_editor.h

@@ -284,6 +284,8 @@ class PublicEditor : public Gtk::Window, public PBD::StatefulDestructible {
 
 	sigc::signal<void> ZoomFocusChanged;
 	sigc::signal<void> ZoomChanged;
+	/** Emitted when the horizontal position of the editor view changes */
+	sigc::signal<void> HorizontalPositionChanged;
 	sigc::signal<void> Resized;
 	sigc::signal<void> Realized;
 	sigc::signal<void,framepos_t> UpdateAllTransportClocks;

gtk2_ardour/route_time_axis.cc

@@ -225,6 +225,7 @@ RouteTimeAxisView::RouteTimeAxisView (PublicEditor& ed, Session* sess, boost::sh
 	}
 
 	_editor.ZoomChanged.connect (sigc::mem_fun(*this, &RouteTimeAxisView::reset_samples_per_unit));
+	_editor.HorizontalPositionChanged.connect (sigc::mem_fun (*this, &RouteTimeAxisView::horizontal_position_changed));
 	ColorsChanged.connect (sigc::mem_fun (*this, &RouteTimeAxisView::color_handler));
 
 	PropertyList* plist = new PropertyList();
@@ -871,6 +872,14 @@ RouteTimeAxisView::reset_samples_per_unit ()
 	set_samples_per_unit (_editor.get_current_zoom());
 }
 
+void
+RouteTimeAxisView::horizontal_position_changed ()
+{
+	if (_view) {
+		_view->horizontal_position_changed ();
+	}
+}
+
 void
 RouteTimeAxisView::set_samples_per_unit (double spu)
 {

gtk2_ardour/route_time_axis.h

@@ -210,6 +210,7 @@ protected:
 	void set_route_group_from_menu (ARDOUR::RouteGroup *);
 
 	void reset_samples_per_unit ();
+	void horizontal_position_changed ();
 
 	void select_track_color();
 

gtk2_ardour/streamview.h

@@ -72,6 +72,7 @@ public:
 
 	virtual int set_samples_per_unit (gdouble spp);
 	gdouble     get_samples_per_unit () { return _samples_per_unit; }
+	virtual void horizontal_position_changed () {}
 
  	void set_layer_display (LayerDisplay);
 	LayerDisplay layer_display () const { return _layer_display; }