tweak rectangle bounding box computation

[ardour.git] / libs / canvas / rectangle.cc

diff --git a/libs/canvas/rectangle.cc b/libs/canvas/rectangle.cc
index bb1198c1bb1c1c7b9ce394497b867a80eff7cfa8..06a41e074c0fe6514c58b40ca12b7cdfc4778bb3 100644 (file)
--- a/libs/canvas/rectangle.cc
+++ b/libs/canvas/rectangle.cc
@@ -36,7 +36,6 @@ Rectangle::Rectangle (Group* parent)
        , Fill (parent)
        , _outline_what ((What) (LEFT | RIGHT | TOP | BOTTOM))
 {
-
 }
 
 Rectangle::Rectangle (Group* parent, Rect const & rect)
@@ -50,93 +49,89 @@ 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,
-        * clamp what we are drawing using the absolute end of the visible
-        * canvas, converting to item-space coordinates, of course.
-        */
+       Rect self = item_to_window (_rect);
+       boost::optional<Rect> r = self.intersection (area);
 
-       Rect plot = _rect;
-       Rect visible = _canvas->visible_area();
-       Duple visible_end = canvas_to_item (Duple (visible.x1, visible.y1));
+       if (!r) {
+               std::cerr << whatami() << '/' << name << " not covered by render area! ... " << self << " vs. " << area << std::endl;
+               return;
+       }
 
-       plot.x1 = min (plot.x1, visible_end.x);
-       plot.y1 = min (plot.y1, visible_end.y); 
+       Rect draw = r.get ();
 
        if (_fill) {
-               setup_fill_context (context);
-               cerr << "Fill rect: " << plot << endl;
-               context->rectangle (plot.x0, plot.y0, plot.width(), plot.height());
-               
-               if (!_outline) {
-                       context->fill ();
+               if (_stops.empty()) {
+                       setup_fill_context (context);
                } else {
-                       
-                       /* special/common case: outline the entire rectangle is
-                        * requested, so just use the same path for the fill
-                        * and stroke.
-                        */
-
-                       if (_outline_what == What (LEFT|RIGHT|BOTTOM|TOP)) {
-                               context->fill_preserve();
-                               setup_outline_context (context);
-                               context->stroke ();
-                       } else {
-                               context->fill ();
-                       }
+                       setup_gradient_context (context, self, Duple (draw.x0, draw.y0));
                }
-       } 
+               context->rectangle (draw.x0, draw.y0, draw.width(), draw.height());
+               context->fill ();
+       }
        
        if (_outline) {
-               
+
                setup_outline_context (context);
 
                if (_outline_what == What (LEFT|RIGHT|BOTTOM|TOP)) {
-
-                       /* if we filled and use full outline, we are already
-                        * done. otherwise, draw the frame here.
-                        */
-
-                       if (!_fill) { 
-                               context->rectangle (plot.x0, plot.y0, plot.width(), plot.height());
-                               context->stroke ();
-                       }
                        
+                       context->rectangle (self.x0 + 0.5, self.y0 + 0.5, self.width(), self.height());
+
                } else {
+
+                       context->set_line_cap (Cairo::LINE_CAP_SQUARE);
                        
+                       /* see the cairo FAQ on single pixel lines to see why we do
+                        * this expansion of the perimeter.
+                        */
+
                        if (_outline_what & LEFT) {
-                               context->move_to (plot.x0, plot.y0);
-                               context->line_to (plot.x0, plot.y1);
+                               /* vertical line: move x-coordinate by 0.5 pixels */
+                               context->move_to (self.x0 + 0.5, self.y0);
+                               context->line_to (self.x0 + 0.5, self.y1);
                        }
                        
                        if (_outline_what & BOTTOM) {
-                               context->move_to (plot.x0, plot.y1);
-                               context->line_to (plot.x1, plot.y1);
+                               /* horizontal line: move y-coordinate by 0.5 pixels */
+                               context->move_to (self.x0, self.y1 - 0.5);
+                               context->line_to (self.x1, self.y1 - 0.5);
                        }
                        
                        if (_outline_what & RIGHT) {
-                               context->move_to (plot.x1, plot.y0);
-                               context->line_to (plot.x1, plot.y1);
+                               /* vertical line: move x-coordinate by 0.5 pixels */
+                               context->move_to (self.x1 - 0.5, self.y0);
+                               context->line_to (self.x1 - 0.5, self.y1);
                        }
                        
                        if (_outline_what & TOP) {
-                               context->move_to (plot.x0, plot.y0);
-                               context->line_to (plot.x1, plot.y0);
+                               /* horizontal line: move y-coordinate by 0.5 pixels */
+                               context->move_to (self.x0, self.y0 + 0.5);
+                               context->line_to (self.x1, self.y0 + 0.5);
                        }
-                       
-                       context->stroke ();
                }
+               
+               context->stroke ();
        }
 }
 
 void
 Rectangle::compute_bounding_box () const
 {
-       Rect r = _rect.fix ();
-       _bounding_box = boost::optional<Rect> (r.expand (_outline_width / 2));
-       
+       if (!_rect.empty()) {
+               Rect r = _rect.fix ();
+
+               /* our outlines are always inside our coordinates, but we have
+                * to ensure that our bounding box fully *contains* the
+                * rectangle
+                *
+                * XXX: or something like that, waffle.
+                *
+                */
+               _bounding_box = r.expand (1.0);
+       }
+
        _bounding_box_dirty = false;
 }