since we now expand rectangles to the right always, adjust the bounding box computation

diff --git a/libs/canvas/rectangle.cc b/libs/canvas/rectangle.cc
index 0b7a76b8a778cc5b1befa2e0d51732fb0c81320f..57aa92d040ae2b6b3bd6825613252430c9104f22 100644 (file)
--- a/libs/canvas/rectangle.cc
+++ b/libs/canvas/rectangle.cc
@@ -85,14 +85,24 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
 
                } else {
 
-                       // context->set_line_cap (Cairo::LINE_CAP_SQUARE);
-                       
                        if (_outline_what & LEFT) {
                                /* 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 & TOP) {
+                               /* 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);
+                       }
+
+                       /* in theory, you'd expect us to adjust these two by
+                        * MINUS 0.5 pixels. But the way that Cairo apparently
+                        * does rounding can lead that approach to draw on the
+                        * wrong pixel coordinate. So we add 0.5 even here.
+                        */
+
                        if (_outline_what & BOTTOM) {
                                /* horizontal line: move y-coordinate by 0.5 pixels */
                                context->move_to (self.x0, self.y1 + 0.5);
@@ -105,11 +115,6 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
                                context->line_to (self.x1 + 0.5, self.y1);
                        }
                        
-                       if (_outline_what & TOP) {
-                               /* 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 ();
@@ -121,15 +126,14 @@ Rectangle::compute_bounding_box () const
 {
        if (!_rect.empty()) {
                Rect r = _rect.fix ();
+               /* take into acount the 0.5 addition to the bounding
+                  box for the right and bottom edges, see ::render() above
+               */
 
-               /* 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 = _rect.fix ();
+               r.x1 += 0.5;
+               r.y1 += 0.5;
+
+               _bounding_box = r;
        }
 
        _bounding_box_dirty = false;