basically operational switch to canvas drawing coordinates, although text and waves don't work, and redraw areas are too small

14 files changed, 160 insertions, 149 deletions

diff --git a/libs/canvas/arc.cc b/libs/canvas/arc.cc
index c8eaf030e7..eeecd3204a 100644
--- a/libs/canvas/arc.cc
+++ b/libs/canvas/arc.cc
@@ -65,7 +65,10 @@ Arc::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
 	if (_radius <= 0.0 || _arc_degrees <= 0.0) {
 		return;
 	}
-	context->arc (_center.x, _center.y, _radius, _start_degrees * (M_PI/180.0), _arc_degrees * (M_PI/180.0));
+	
+	Duple c = item_to_window (Duple (_center.x, _center.y));
+
+	context->arc (c.x, c.y, _radius, _start_degrees * (M_PI/180.0), _arc_degrees * (M_PI/180.0));
 	setup_fill_context (context);
 	context->fill_preserve ();
 	setup_outline_context (context);
diff --git a/libs/canvas/canvas.cc b/libs/canvas/canvas.cc
index 5987a136db..9c49eb4a87 100644
--- a/libs/canvas/canvas.cc
+++ b/libs/canvas/canvas.cc
@@ -38,7 +38,6 @@ using namespace ArdourCanvas;
 /** Construct a new Canvas */
 Canvas::Canvas ()
 	: _root (this)
-	, _log_renders (true)
 	, _scroll_offset_x (0)
 	, _scroll_offset_y (0)
 {
@@ -68,64 +67,21 @@ Canvas::render (Rect const & area, Cairo::RefPtr<Cairo::Context> const & context
 	}
 #endif
 
-	// checkpoint ("render", "-> render");
 	render_count = 0;
 	
-	context->save ();
-
-#ifdef CANVAS_DEBUG
-	if (getenv ("ARDOUR_REDRAW_CANVAS")) {
-		/* light up the canvas to show redraws */
-		context->set_source_rgba (random()%255 / 255.0,
-					  random()%255 / 255.0,
-					  random()%255 / 255.0,
-					  0.3);
-		context->rectangle (area.x0, area.y0, area.width(), area.height());
-		context->fill ();
-	}
-#endif
-
-	/* clip to the requested area */
-	context->rectangle (area.x0, area.y0, area.width(), area.height());
-	context->clip ();
-
 	boost::optional<Rect> root_bbox = _root.bounding_box();
 	if (!root_bbox) {
 		/* the root has no bounding box, so there's nothing to render */
-		// checkpoint ("render", "no root bbox");
-		context->restore ();
 		return;
 	}
 
-	boost::optional<Rect> draw = root_bbox.get().intersection (area);
+	boost::optional<Rect> draw = root_bbox->intersection (area);
 	if (draw) {
 		/* there's a common area between the root and the requested
 		   area, so render it.
 		*/
-		// checkpoint ("render", "... root");
-		context->stroke ();
-
 		_root.render (*draw, context);
 	}
-
-	if (_log_renders) {
-		_renders.push_back (area);
-	}
-
-	context->restore ();
-
-#ifdef CANVAS_DEBUG
-	if (getenv ("ARDOUR_HARLEQUIN_CANVAS")) {
-		/* light up the canvas to show redraws */
-		context->set_source_rgba (random()%255 / 255.0,
-					  random()%255 / 255.0,
-					  random()%255 / 255.0,
-					  0.4);
-		context->rectangle (area.x0, area.y0, area.width(), area.height());
-		context->fill ();
-	}
-#endif
-	// checkpoint ("render", "<- render");
 }
 
 ostream&
@@ -502,29 +458,9 @@ GtkCanvas::item_going_away (Item* item, boost::optional<Rect> bounding_box)
 bool
 GtkCanvas::on_expose_event (GdkEventExpose* ev)
 {
-
 	Cairo::RefPtr<Cairo::Context> c = get_window()->create_cairo_context ();
-	
-	/* WINDOW  CANVAS
-	 * 0,0     _scroll_offset_x, _scroll_offset_y
-	 */
-
-	/* render using canvas coordinates */
-
-	Rect canvas_area (ev->area.x, ev->area.y, ev->area.x + ev->area.width, ev->area.y + ev->area.height);
-	canvas_area  = canvas_area.translate (Duple (_scroll_offset_x, _scroll_offset_y));
-
-	/* things are going to render to the cairo surface with canvas
-	 * coordinates:
-	 *
-	 *  an item at window/cairo 0,0 will have canvas_coords _scroll_offset_x,_scroll_offset_y
-	 *
-	 * let them render at their natural coordinates by using cairo_translate()
-	 */
-
-	c->translate (-_scroll_offset_x, -_scroll_offset_y);
 
-	render (canvas_area, c);
+	render (Rect (ev->area.x, ev->area.y, ev->area.x + ev->area.width, ev->area.y + ev->area.height), c);
 
 	return true;
 }
diff --git a/libs/canvas/canvas/canvas.h b/libs/canvas/canvas/canvas.h
index 4967e79702..e65abf6b27 100644
--- a/libs/canvas/canvas/canvas.h
+++ b/libs/canvas/canvas/canvas.h
@@ -79,14 +79,6 @@ public:
 
         virtual Cairo::RefPtr<Cairo::Context> context () = 0;
 
-	std::list<Rect> const & renders () const {
-		return _renders;
-	}
-
-	void set_log_renders (bool log) {
-		_log_renders = log;
-	}
-
         Rect canvas_to_window (Rect const&) const;
         Rect window_to_canvas (Rect const&) const;
         Duple canvas_to_window (Duple const&) const;
@@ -117,9 +109,6 @@ protected:
 	/** our root group */
 	RootGroup _root;
 
-	mutable std::list<Rect> _renders;
-	bool _log_renders;
-
         Coord _scroll_offset_x;
         Coord _scroll_offset_y;
 
diff --git a/libs/canvas/canvas/item.h b/libs/canvas/canvas/item.h
index b4ea5671c7..e856c7e149 100644
--- a/libs/canvas/canvas/item.h
+++ b/libs/canvas/canvas/item.h
@@ -57,7 +57,15 @@ public:
 	virtual ~Item ();
 
 	/** Render this item to a Cairo context.
-	 *  @param area Area to draw in this item's coordinates.
+	 *  @param area Area to draw, in **window** coordinates
+	 *
+	 *  Items must convert their own coordinates into window coordinates
+	 *  because Cairo is limited to a fixed point coordinate space that
+	 *  does not extend as far as the Ardour timeline. All rendering must
+	 *  be done using coordinates that do not exceed the (rough) limits
+	 *  of the canvas' window, to avoid odd errors within Cairo as it
+	 *  converts doubles into its fixed point format and then tesselates
+	 *  the results.
 	 */
 	virtual void render (Rect const & area, Cairo::RefPtr<Cairo::Context>) const = 0;
 
@@ -105,8 +113,13 @@ public:
         Duple canvas_to_item (Duple const &) const;
 	void item_to_canvas (Coord &, Coord &) const;
 	Rect item_to_canvas (Rect const &) const;
+	Rect canvas_to_item (Rect const &) const;
         Duple item_to_canvas (Duple const &) const;
 
+        Duple item_to_window (Duple const&) const;
+        Duple window_to_item (Duple const&) const;
+        Rect item_to_window (Rect const&) const;
+
 	void raise_to_top ();
 	void raise (int);
 	void lower_to_bottom ();
diff --git a/libs/canvas/group.cc b/libs/canvas/group.cc
index 028599148b..364d9fe583 100644
--- a/libs/canvas/group.cc
+++ b/libs/canvas/group.cc
@@ -78,8 +78,8 @@ Group::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 		
 #ifdef CANVAS_DEBUG
 	if (DEBUG_ENABLED(PBD::DEBUG::CanvasRender)) {
-		cerr << string_compose ("%1GROUP %2 render %3 items out of %4\n", 
-					_canvas->render_indent(), (name.empty() ? string ("[unnamed]") : name), items.size(), _items.size());
+		cerr << string_compose ("%1GROUP %2 render %5 %3 items out of %4\n", 
+					_canvas->render_indent(), (name.empty() ? string ("[unnamed]") : name), items.size(), _items.size(), area);
 	}
 #endif
 
@@ -105,25 +105,18 @@ Group::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 			continue;
 		}
 
-		/* convert the render area to our child's coordinates */
-		Rect const item_area = (*i)->parent_to_item (area);
-
-		/* intersect the child's render area with the child's bounding box */
-		boost::optional<Rect> r = item_bbox.get().intersection (item_area);
-
-		if (r) {
-			/* render the intersection */
-			context->save ();
-			context->translate ((*i)->position().x, (*i)->position().y);
+		Rect item = (*i)->item_to_window (item_bbox.get());
+		boost::optional<Rect> draw = item.intersection (area);
+		
+		if (draw) {
 #ifdef CANVAS_DEBUG
 			if (DEBUG_ENABLED(PBD::DEBUG::CanvasRender)) {
 				cerr << string_compose ("%1render %2 %3\n", _canvas->render_indent(), (*i)->whatami(),
 							(*i)->name);
 			}
 #endif
-			(*i)->render (r.get(), context);
+			(*i)->render (draw.get(), context);
 			++render_count;
-			context->restore ();
 		} else {
 #ifdef CANVAS_DEBUG
 			if (DEBUG_ENABLED(PBD::DEBUG::CanvasRender)) {
diff --git a/libs/canvas/image.cc b/libs/canvas/image.cc
index b13859aeda..4a9bcdf8f1 100644
--- a/libs/canvas/image.cc
+++ b/libs/canvas/image.cc
@@ -43,10 +43,13 @@ Image::render (Rect const& area, Cairo::RefPtr<Cairo::Context> context) const
 							_pending->stride);
 		_current = _pending;
 	}
+	
+	Rect self = item_to_window (Rect (0, 0, _width, _height));
+	boost::optional<Rect> draw = self.intersection (area);
 
-	if (_surface) {
+	if (_surface && draw) {
 		context->set_source (_surface, 0, 0);
-		context->rectangle (area.x0, area.y0, area.width(), area.height());
+		context->rectangle (draw->x0, draw->y0, draw->width(), draw->height());
 		context->fill ();
 	}
 }
diff --git a/libs/canvas/item.cc b/libs/canvas/item.cc
index 569d03f81f..dca3064bce 100644
--- a/libs/canvas/item.cc
+++ b/libs/canvas/item.cc
@@ -127,6 +127,20 @@ Item::canvas_to_item (ArdourCanvas::Duple const & d) const
 	return d.translate (offset);
 }
 
+ArdourCanvas::Rect
+Item::canvas_to_item (ArdourCanvas::Rect const & d) const
+{
+	Item const * i = this;
+	Duple offset;
+
+	while (i) {
+		offset = offset.translate (-(i->position()));
+		i = i->parent();
+	}
+
+	return d.translate (offset);
+}
+
 void
 Item::item_to_canvas (Coord& x, Coord& y) const
 {
@@ -145,6 +159,24 @@ Item::canvas_to_item (Coord& x, Coord& y) const
 	y = d.y;
 }
 
+Duple
+Item::item_to_window (ArdourCanvas::Duple const & d) const
+{
+	return _canvas->canvas_to_window (item_to_canvas (d));
+}
+
+Duple
+Item::window_to_item (ArdourCanvas::Duple const & d) const
+{
+	return _canvas->window_to_canvas (canvas_to_item (d));
+}
+
+Rect
+Item::item_to_window (ArdourCanvas::Rect const & r) const
+{
+	return _canvas->canvas_to_window (item_to_canvas (r));
+}
+
 /** Set the position of this item in the parent's coordinates */
 void
 Item::set_position (Duple p)
diff --git a/libs/canvas/line.cc b/libs/canvas/line.cc
index 7c5852f4b2..b6a802b8df 100644
--- a/libs/canvas/line.cc
+++ b/libs/canvas/line.cc
@@ -56,8 +56,10 @@ void
 Line::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
 {
 	setup_outline_context (context);
-	context->move_to (_points[0].x, _points[0].y);
-	context->line_to (_points[1].x, _points[1].y);
+	Duple p0 = item_to_window (Duple (_points[0].x, _points[0].y));
+	Duple p1 = item_to_window (Duple (_points[1].x, _points[1].y));
+	context->move_to (p0.x, p0.y);
+	context->line_to (p1.x, p1.y);
 	context->stroke ();
 }
 
diff --git a/libs/canvas/line_set.cc b/libs/canvas/line_set.cc
index c3ee5d44b9..5aefe1bf47 100644
--- a/libs/canvas/line_set.cc
+++ b/libs/canvas/line_set.cc
@@ -73,8 +73,10 @@ LineSet::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 		} else if (i->y > area.y0) {
 			set_source_rgba (context, i->color);
 			context->set_line_width (i->width);
-			context->move_to (area.x0, i->y);
-			context->line_to (area.x1, i->y);
+			Duple p0 = item_to_window (Duple (area.x0, i->y));
+			Duple p1 = item_to_window (Duple (area.x1, i->y));
+			context->move_to (p0.x, p0.y);
+			context->line_to (p1.x, p1.y);
 			context->stroke ();
 		}
 	}
diff --git a/libs/canvas/poly_item.cc b/libs/canvas/poly_item.cc
index 6c9f0c98ab..55ebb46bd3 100644
--- a/libs/canvas/poly_item.cc
+++ b/libs/canvas/poly_item.cc
@@ -70,9 +70,11 @@ PolyItem::render_path (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> cont
 	bool done_first = false;
 	for (Points::const_iterator i = _points.begin(); i != _points.end(); ++i) {
 		if (done_first) {
-			context->line_to (i->x, i->y);
+			Duple c = item_to_window (Duple (i->x, i->y));
+			context->line_to (c.x, c.y);
 		} else {
-			context->move_to (i->x, i->y);
+			Duple c = item_to_window (Duple (i->x, i->y));
+			context->move_to (c.x, c.y);
 			done_first = true;
 		}
 	}
@@ -95,15 +97,18 @@ PolyItem::render_curve (Rect const & area, Cairo::RefPtr<Cairo::Context> context
 
 		if (done_first) {
 
-			context->curve_to (cp1->x, cp1->y,
-					   cp2->x, cp2->y,
-					   i->x, i->y);
+			Duple c1 = item_to_window (Duple (cp1->x, cp1->y));
+			Duple c2 = item_to_window (Duple (cp2->x, cp2->y));
+			Duple c3 = item_to_window (Duple (i->x, i->y));
+
+			context->curve_to (c1.x, c1.y, c2.x, c2.y, c3.x, c3.y);
 
 			cp1++;
 			cp2++;
 			
 		} else {
 
+			Duple c = item_to_window (Duple (i->x, i->y));
 			context->move_to (i->x, i->y);
 			done_first = true;
 		}
diff --git a/libs/canvas/polygon.cc b/libs/canvas/polygon.cc
index 43d7c60cf4..1103cedbee 100644
--- a/libs/canvas/polygon.cc
+++ b/libs/canvas/polygon.cc
@@ -37,7 +37,9 @@ Polygon::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 		render_path (area, context);
 		
 		if (!_points.empty ()) {
-			context->move_to (_points.front().x, _points.front().y);
+			/* close path */
+			Duple p = item_to_window (Duple (_points.front().x, _points.front().y));
+			context->move_to (p.x, p.y);
 		}
 
 		context->stroke_preserve ();
diff --git a/libs/canvas/rectangle.cc b/libs/canvas/rectangle.cc
index bb1198c1bb..7abf13216b 100644
--- a/libs/canvas/rectangle.cc
+++ b/libs/canvas/rectangle.cc
@@ -50,7 +50,7 @@ Rectangle::Rectangle (Group* parent, Rect const & rect)
 }
 
 void
-Rectangle::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
+Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 {
 	/* Cairo goes a little (!) wrong when asked to fill/stroke rectangles that
 	 * extend way beyond the surface boundaries. To avoid this issue,
@@ -58,17 +58,13 @@ Rectangle::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context)
 	 * canvas, converting to item-space coordinates, of course.
 	 */
 
-	Rect plot = _rect;
-	Rect visible = _canvas->visible_area();
-	Duple visible_end = canvas_to_item (Duple (visible.x1, visible.y1));
+	Rect self = item_to_window (_rect);
+	boost::optional<Rect> draw = self.intersection (area);
 
-	plot.x1 = min (plot.x1, visible_end.x);
-	plot.y1 = min (plot.y1, visible_end.y);	
-
-	if (_fill) {
+	if (_fill && draw) {
 		setup_fill_context (context);
-		cerr << "Fill rect: " << plot << endl;
-		context->rectangle (plot.x0, plot.y0, plot.width(), plot.height());
+
+		context->rectangle (draw->x0, draw->y0, draw->width(), draw->height());
 		
 		if (!_outline) {
 			context->fill ();
@@ -100,30 +96,30 @@ Rectangle::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context)
 			 */
 
 			if (!_fill) { 
-				context->rectangle (plot.x0, plot.y0, plot.width(), plot.height());
+				context->rectangle (draw->x0, draw->y0, draw->width(), draw->height());
 				context->stroke ();
 			}
 			
 		} else {
 			
 			if (_outline_what & LEFT) {
-				context->move_to (plot.x0, plot.y0);
-				context->line_to (plot.x0, plot.y1);
+				context->move_to (draw->x0, draw->y0);
+				context->line_to (draw->x0, draw->y1);
 			}
 			
 			if (_outline_what & BOTTOM) {
-				context->move_to (plot.x0, plot.y1);
-				context->line_to (plot.x1, plot.y1);
+				context->move_to (draw->x0, draw->y1);
+				context->line_to (draw->x1, draw->y1);
 			}
 			
 			if (_outline_what & RIGHT) {
-				context->move_to (plot.x1, plot.y0);
-				context->line_to (plot.x1, plot.y1);
+				context->move_to (draw->x1, draw->y0);
+				context->line_to (draw->x1, draw->y1);
 			}
 			
 			if (_outline_what & TOP) {
-				context->move_to (plot.x0, plot.y0);
-				context->line_to (plot.x1, plot.y0);
+				context->move_to (draw->x0, draw->y0);
+				context->line_to (draw->x1, draw->y0);
 			}
 			
 			context->stroke ();
diff --git a/libs/canvas/text.cc b/libs/canvas/text.cc
index c0bac2f7ee..e4575de3b5 100644
--- a/libs/canvas/text.cc
+++ b/libs/canvas/text.cc
@@ -96,6 +96,8 @@ Text::redraw (Cairo::RefPtr<Cairo::Context> context) const
 	 * ::render 
 	 */
 
+	cerr << "rendered \"" << layout->get_text() << "\" into image\n";
+
 	_need_redraw = false;
 }
 
@@ -136,7 +138,7 @@ Text::compute_bounding_box () const
 }
 
 void
-Text::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
+Text::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 {
 	if (_text.empty()) {
 		return;
@@ -146,8 +148,12 @@ Text::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) cons
 		redraw (context);
 	}
 	
+	
+	Rect self = item_to_window (Rect (0, 0, min (_clamped_width, _width), _height));
+	cerr << "Draw \"" << _text << "\" @ " << self.x0 << ", " << self.y0 << ' ' << self.width() << " x " << self.height() << endl;
+	context->rectangle (self.x0, self.y0, self.width(), self.height());
 	context->set_source (_image, 0, 0);
-	context->rectangle (0, 0, min (_clamped_width, _width), _height);
+	//context->set_source_rgb (0.3, 0.4, 0.02);
 	context->fill ();
 }
 
diff --git a/libs/canvas/wave_view.cc b/libs/canvas/wave_view.cc
index 4535b11983..1edbf89c87 100644
--- a/libs/canvas/wave_view.cc
+++ b/libs/canvas/wave_view.cc
@@ -133,13 +133,13 @@ WaveView::set_samples_per_pixel (double samples_per_pixel)
 static inline double
 to_src_sample_offset (frameoffset_t src_sample_start, double pixel_offset, double spp)
 {
-	return src_sample_start + (pixel_offset * spp);
+	return llrintf (src_sample_start + (pixel_offset * spp));
 }
 
 static inline double
 to_pixel_offset (frameoffset_t src_sample_start, double sample_offset, double spp)
 {
-	return (sample_offset - src_sample_start) / spp;
+	return llrintf ((sample_offset - src_sample_start) / spp);
 }
 
 void
@@ -151,32 +151,43 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 		return;
 	}
 
-	/* These are all pixel (integer) coordinates from the left hand edge of
-	 * the waveview.
-	 */
-	
-	double       start = area.x0;
-	double const end   = area.x1;
-	double const rend  = _region->length() / _samples_per_pixel;
+	Rect self = item_to_window (Rect (0.0, 0.0, _region->length() / _samples_per_pixel, _height));
+	boost::optional<Rect> draw = self.intersection (area);
+
+	context->rectangle (self.x0, self.y0, self.width(), self.height());
+	context->set_source_rgb (1.0, 0.0, 0.0);
+	context->stroke ();
+
+	if (!draw) {
+		return;
+	}
+
+	/* pixel coordinates */
+
+	double       start = draw->x0;
+	double const end   = draw->x1;
 
 	list<CacheEntry*>::iterator cache = _cache.begin ();
-#if 0
-	cerr << name << " cache contains " << _cache.size() << endl;
+
+	cerr << name << " draw " << area << "self = " << self << "\n\twill use " << draw.get() << endl;
+#if 1
+	cerr << "  Cache contains " << _cache.size() << endl;
 	while (cache != _cache.end()) {
-		cerr << "\tsamples " << (*cache)->start() << " .. " << (*cache)->end()
-		     << " pixels " 
+		cerr << "\tsample span " << (*cache)->start() << " .. " << (*cache)->end()
+		     << " pixel span " 
 		     << to_pixel_offset (_region_start, (*cache)->start(), _samples_per_pixel)
 		     << " .. "
 		     << to_pixel_offset (_region_start, (*cache)->end(), _samples_per_pixel)
 		     << endl;
 		++cache;
 	}
-
 	cache = _cache.begin();
 #endif
 
 	while ((end - start) > 1.0) {
 
+		cerr << "***** RANGE = " << start << " .. " << end << " = " << end - start << endl;
+
 		frameoffset_t start_sample_offset = to_src_sample_offset (_region_start, start, _samples_per_pixel);
 
 		/* Step through cache entries that end at or before our current position */
@@ -197,6 +208,8 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 
 		if (cache == _cache.end ()) {
 
+			cerr << "Nothing in cache spans\n";
+
 			/* Case 1: we have run out of cache entries, so make a new one for
 			   the whole required area and put it in the list.
 			   
@@ -209,7 +222,12 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 			   the region actually is, so clamp with that too.
 			*/
 
+			double const rend  = _region->length() / _samples_per_pixel;
 			double const endpoint = min (rend, max (end, start + _canvas->visible_area().width()));
+
+			cerr << "New cache entry for " << start_sample_offset << " .. " << to_src_sample_offset (_region_start, endpoint, _samples_per_pixel)
+			     << endl;
+
 			CacheEntry* c = new CacheEntry (this, 
 							start_sample_offset,
 							to_src_sample_offset (_region_start, endpoint, _samples_per_pixel),
@@ -228,20 +246,24 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 			 * or the end of the render area, whichever comes first.
 			 */
 
-			double    end_pixel = min (rend, end);
-			double end_sample_offset = to_src_sample_offset (_region_start, end_pixel, _samples_per_pixel);
+			double    end_pixel;
+			double end_sample_offset;
 			int npeaks;
 
 			if (end_sample_offset < (*cache)->start()) {
-				npeaks = end_pixel - start;
-				assert (npeaks > 0);
+				double const rend  = _region->length() / _samples_per_pixel;
+				end_sample_offset = to_src_sample_offset (_region_start, end_pixel, _samples_per_pixel);
+				end_pixel = min (rend, end);
 			} else {
 				end_sample_offset = (*cache)->start();
 				end_pixel = to_pixel_offset (_region_start, end_sample_offset, _samples_per_pixel);
-				npeaks = end_pixel - npeaks;
-				assert (npeaks > 0);
 			}
 		
+			npeaks = end_pixel - start;
+			assert (npeaks > 0);
+
+			cerr << "New fill-in cache entry for " << start_sample_offset << " .. " << end_sample_offset << endl;
+
 			CacheEntry* c = new CacheEntry (this,
 							start_sample_offset,
 							end_sample_offset,
@@ -257,14 +279,18 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 			   we have left, so render it.
 			*/
 
+			cerr << "found suitable cache entry\n";
+
 			image = *cache;
 			++cache;
 
 		}
 
+		
+
 		double this_end = min (end, to_pixel_offset (_region_start, image->end (), _samples_per_pixel));
 		double const image_origin = to_pixel_offset (_region_start, image->start(), _samples_per_pixel);
-#if 0
+#if 1
 		cerr << "\t\tDraw image between "
 		     << start
 		     << " .. "
@@ -280,8 +306,11 @@ WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) cons
 		     << endl;
 #endif
 
-		context->rectangle (start, area.y0, this_end - start, area.height());
-		context->set_source (image->image(), image_origin, 0);
+		cerr << "Fill rect " << draw->x0 << ", " << self.y0 << ' ' << draw->width() << " x " << draw->height() << endl;
+
+		context->rectangle (start, draw->y0, this_end - start, _height);
+		// context->set_source (image->image(), image_origin, self.y0 - draw->y0);
+		context->set_source_rgb (0.0, 0.0, 1.0);
 		context->fill ();
 		
 		start = this_end;