fix clamping of line and rect coordinates to avoid issues with cairo when drawing way outside a surface's dimensions; move various coordinate methods down to Canvas, because they don't require GTK information; make visible_area() a Canvas virtual method so that we don't have to cast to call it

7 files changed, 76 insertions, 69 deletions

diff --git a/libs/canvas/canvas.cc b/libs/canvas/canvas.cc
index 726e4fb2fc..ff624be8fb 100644
--- a/libs/canvas/canvas.cc
+++ b/libs/canvas/canvas.cc
@@ -198,6 +198,30 @@ Canvas::item_changed (Item* item, boost::optional<Rect> pre_change_bounding_box)
 	}
 }
 
+Duple
+Canvas::window_to_canvas (Duple const & d) const
+{
+	return d.translate (Duple (_scroll_offset_x, _scroll_offset_y));
+}
+
+Duple
+Canvas::canvas_to_window (Duple const & d) const
+{
+	return d.translate (Duple (-_scroll_offset_x, -_scroll_offset_y));
+}	
+
+Rect
+Canvas::window_to_canvas (Rect const & r) const
+{
+	return r.translate (Duple (_scroll_offset_x, _scroll_offset_y));
+}
+
+Rect
+Canvas::canvas_to_window (Rect const & r) const
+{
+	return r.translate (Duple (-_scroll_offset_x, -_scroll_offset_y));
+}	
+
 /** Called when an item has moved.
  *  @param item Item that has moved.
  *  @param pre_change_parent_bounding_box The bounding box of the item before
@@ -553,6 +577,15 @@ GtkCanvas::ungrab ()
 	_grabbed_item = 0;
 }
 
+/** @return The visible area of the canvas, in canvas coordinates */
+Rect
+GtkCanvas::visible_area () const
+{
+	Distance const xo = _scroll_offset_x;
+	Distance const yo = _scroll_offset_y;
+	return Rect (xo, yo, xo + get_allocation().get_width (), yo + get_allocation().get_height ());
+}
+
 /** Create a GtkCanvaSViewport.
  *  @param hadj Adjustment to use for horizontal scrolling.
  *  @param vadj Adjustment to use for vertica scrolling.
@@ -575,30 +608,6 @@ GtkCanvasViewport::scrolled ()
 	queue_draw ();
 }
 
-Duple
-GtkCanvas::window_to_canvas (Duple const & d) const
-{
-	return d.translate (Duple (_scroll_offset_x, _scroll_offset_y));
-}
-
-Duple
-GtkCanvas::canvas_to_window (Duple const & d) const
-{
-	return d.translate (Duple (-_scroll_offset_x, -_scroll_offset_y));
-}	
-
-Rect
-GtkCanvas::window_to_canvas (Rect const & r) const
-{
-	return r.translate (Duple (_scroll_offset_x, _scroll_offset_y));
-}
-
-Rect
-GtkCanvas::canvas_to_window (Rect const & r) const
-{
-	return r.translate (Duple (-_scroll_offset_x, -_scroll_offset_y));
-}	
-
 /** Handler for when GTK asks us what minimum size we want.
  *  @param req Requsition to fill in.
  */
@@ -612,26 +621,3 @@ GtkCanvasViewport::on_size_request (Gtk::Requisition* req)
 	req->height = 16;
 }
 
-/** Convert window coordinates to canvas coordinates by taking into account
- *  where we are scrolled to.
- *  @param wx Window x.
- *  @param wy Window y.
- *  @param cx Filled in with canvas x.
- *  @param cy Filled in with canvas y.
- */
-void
-GtkCanvasViewport::window_to_canvas (int wx, int wy, Coord& cx, Coord& cy) const
-{
-	Duple d = _canvas.window_to_canvas (Duple (wx, wy));
-	cx = d.x;
-	cy = d.y;
-}
-
-/** @return The visible area of the canvas, in canvas coordinates */
-Rect
-GtkCanvasViewport::visible_area () const
-{
-	Distance const xo = hadjustment.get_value ();
-	Distance const yo = vadjustment.get_value ();
-	return Rect (xo, yo, xo + get_allocation().get_width (), yo + get_allocation().get_height ());
-}
diff --git a/libs/canvas/canvas/canvas.h b/libs/canvas/canvas/canvas.h
index 9b31844e7e..8b8ed37cd4 100644
--- a/libs/canvas/canvas/canvas.h
+++ b/libs/canvas/canvas/canvas.h
@@ -87,7 +87,25 @@ public:
 		_log_renders = log;
 	}
 
+        Rect canvas_to_window (Rect const&) const;
+        Rect window_to_canvas (Rect const&) const;
+        Duple canvas_to_window (Duple const&) const;
+        Duple window_to_canvas (Duple const&) const;
+
+        void canvas_to_window (Coord cx, Coord cy, Coord& wx, Coord& wy) {
+		Duple d = canvas_to_window (Duple (cx, cy));
+		wx = d.x;
+		wy = d.y;
+        }
+
+        void window_to_canvas (Coord wx, Coord wy, Coord& cx, Coord& cy) {
+		Duple d = window_to_canvas (Duple (wx, wy));
+		cx = d.x;
+		cy = d.y;
+        }
+
         void scroll_to (Coord x, Coord y);
+        virtual Rect visible_area () const = 0;
 
         std::string indent() const;
         std::string render_indent() const;
@@ -119,11 +137,7 @@ public:
 
 	Cairo::RefPtr<Cairo::Context> context ();
 
-        Rect canvas_to_window (Rect const&) const;
-        Rect window_to_canvas (Rect const&) const;
-
-        Duple canvas_to_window (Duple const&) const;
-        Duple window_to_canvas (Duple const&) const;
+	Rect visible_area () const;
 
 protected:
 	bool on_expose_event (GdkEventExpose *);
@@ -162,9 +176,6 @@ public:
 		return &_canvas;
 	}
 
-	void window_to_canvas (int, int, Coord &, Coord &) const;
-	Rect visible_area () const;
-
 protected:
 	void on_size_request (Gtk::Requisition *);
 
diff --git a/libs/canvas/canvas/types.h b/libs/canvas/canvas/types.h
index 606c832ba5..37c0c213ea 100644
--- a/libs/canvas/canvas/types.h
+++ b/libs/canvas/canvas/types.h
@@ -56,6 +56,7 @@ struct Duple
 
 extern Duple operator- (Duple const &);
 extern Duple operator+ (Duple const &, Duple const &);
+extern bool operator== (Duple const &, Duple const &);
 extern Duple operator- (Duple const &, Duple const &);
 extern Duple operator/ (Duple const &, double);
 extern std::ostream & operator<< (std::ostream &, Duple const &);
diff --git a/libs/canvas/item.cc b/libs/canvas/item.cc
index da551fade6..f5aa39d20d 100644
--- a/libs/canvas/item.cc
+++ b/libs/canvas/item.cc
@@ -370,7 +370,7 @@ Item::dump (ostream& o) const
 {
 	boost::optional<ArdourCanvas::Rect> bb = bounding_box();
 
-	o << _canvas->indent() << whatami() << ' ' << this;
+	o << _canvas->indent() << whatami() << ' ' << this << " Visible ? " << _visible;
 	o << " @ " << position();
 	
 #ifdef CANVAS_DEBUG
diff --git a/libs/canvas/line.cc b/libs/canvas/line.cc
index 7baa0e1e73..2894a80a89 100644
--- a/libs/canvas/line.cc
+++ b/libs/canvas/line.cc
@@ -24,6 +24,7 @@
 #include "canvas/types.h"
 #include "canvas/debug.h"
 #include "canvas/utils.h"
+#include "canvas/canvas.h"
 
 using namespace std;
 using namespace ArdourCanvas;
@@ -55,14 +56,8 @@ void
 Line::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
 {
 	setup_outline_context (context);
-
-	Duple plot[2] = {
-		Duple (min (_points[0].x, CAIRO_MAX), min (_points[0].y, CAIRO_MAX)),
-		Duple (min (_points[1].x, CAIRO_MAX), min (_points[1].y, CAIRO_MAX))
-	};
-
-	context->move_to (plot[0].x, plot[0].y);
-	context->line_to (plot[1].x, plot[1].y);
+	context->move_to (_points[0].x, _points[0].y);
+	context->line_to (_points[1].x, _points[1].y);
 	context->stroke ();
 }
 
diff --git a/libs/canvas/rectangle.cc b/libs/canvas/rectangle.cc
index 8aa8b6161c..38106a6550 100644
--- a/libs/canvas/rectangle.cc
+++ b/libs/canvas/rectangle.cc
@@ -21,6 +21,8 @@
 #include <cairomm/context.h>
 #include "pbd/stacktrace.h"
 #include "pbd/compose.h"
+
+#include "canvas/canvas.h"
 #include "canvas/rectangle.h"
 #include "canvas/debug.h"
 #include "canvas/utils.h"
@@ -50,10 +52,18 @@ Rectangle::Rectangle (Group* parent, Rect const & rect)
 void
 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,
+	 * clamp what we are drawing using the absolute end of the visible
+	 * 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));
 
-	plot.x1 = min (plot.x1, CAIRO_MAX);
-	plot.y1 = min (plot.y1, CAIRO_MAX);
+	plot.x1 = min (plot.x1, visible_end.x);
+	plot.y1 = min (plot.y1, visible_end.y);	
 
 	if (_fill) {
 		setup_fill_context (context);
diff --git a/libs/canvas/types.cc b/libs/canvas/types.cc
index c2612a0b2b..dfd934b126 100644
--- a/libs/canvas/types.cc
+++ b/libs/canvas/types.cc
@@ -25,9 +25,7 @@
 using namespace std;
 using namespace ArdourCanvas;
 
-Coord const ArdourCanvas::COORD_MAX = DBL_MAX;
-/* XXX: empirically arrived at */
-Coord const ArdourCanvas::CAIRO_MAX = 65536;
+Coord const ArdourCanvas::COORD_MAX = 1.7e307;
 
 static inline Coord
 safe_add (Coord a, Coord b)
@@ -132,6 +130,12 @@ ArdourCanvas::operator+ (Duple const & a, Duple const & b)
 	return Duple (safe_add (a.x, b.x), safe_add (a.y, b.y));
 }
 
+bool
+ArdourCanvas::operator== (Duple const & a, Duple const & b)
+{
+	return a.x == b.x && a.y == b.y;
+}
+
 Duple
 ArdourCanvas::operator- (Duple const & a, Duple const & b)
 {