add support for rounded corners to Canvas::Rectangle

libs/canvas/canvas/rectangle.h

@@ -76,6 +76,8 @@ public:
          */
         double vertical_fraction (double y) const;
 
+        void set_corner_radius (double d);
+
 	enum What {
 		NOTHING = 0x0,
 		LEFT = 0x1,
@@ -94,6 +96,7 @@ public:
 	 */
 	Rect _rect;
 	What _outline_what;
+	double _corner_radius;
 };
 
 }

libs/canvas/rectangle.cc

@@ -20,8 +20,11 @@
 
 #include <iostream>
 #include <cairomm/context.h>
+
 #include "pbd/compose.h"
 
+#include "gtkmm2ext/utils.h"
+
 #include "canvas/canvas.h"
 #include "canvas/rectangle.h"
 #include "canvas/debug.h"
@@ -32,6 +35,7 @@ using namespace ArdourCanvas;
 Rectangle::Rectangle (Canvas* c)
 	: Item (c)
 	, _outline_what ((What) (LEFT | RIGHT | TOP | BOTTOM))
+	, _corner_radius (0.0)
 {
 }
 
@@ -39,12 +43,14 @@ Rectangle::Rectangle (Canvas* c, Rect const & rect)
 	: Item (c)
 	, _rect (rect)
 	, _outline_what ((What) (LEFT | RIGHT | TOP | BOTTOM))
+	, _corner_radius (0.0)
 {
 }
 
 Rectangle::Rectangle (Item* parent)
 	: Item (parent)
 	, _outline_what ((What) (LEFT | RIGHT | TOP | BOTTOM))
+	, _corner_radius (0.0)
 {
 }
 
@@ -52,6 +58,7 @@ Rectangle::Rectangle (Item* parent, Rect const & rect)
 	: Item (parent)
 	, _rect (rect)
 	, _outline_what ((What) (LEFT | RIGHT | TOP | BOTTOM))
+	, _corner_radius (0.0)
 {
 }
 
@@ -69,6 +76,13 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
 		return;
 	}
 
+
+	if (_corner_radius) {
+		context->save ();
+		Gtkmm2ext::rounded_rectangle (context, self.x0, self.y0, self.width(), self.height(), _corner_radius);
+		context->clip ();
+	}
+
 	if (_fill && !_transparent) {
 		if (_stops.empty()) {
 			setup_fill_context (context);
@@ -76,7 +90,11 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
 			setup_gradient_context (context, self, Duple (draw.x0, draw.y0));
 		}
 
-		context->rectangle (draw.x0, draw.y0, draw.width(), draw.height());
+		if (_corner_radius) {
+			Gtkmm2ext::rounded_rectangle (context, draw.x0, draw.y0, draw.width(), draw.height(), _corner_radius);
+		} else {
+			context->rectangle (draw.x0, draw.y0, draw.width(), draw.height());
+		}
 		context->fill ();
 	}
 
@@ -104,7 +122,11 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
 
 		if (_outline_what == What (LEFT|RIGHT|BOTTOM|TOP)) {
 
-			context->rectangle (self.x0, self.y0, self.width(), self.height());
+			if (_corner_radius) {
+				Gtkmm2ext::rounded_rectangle (context, self.x0, self.y0, self.width(), self.height(), _corner_radius);
+			} else {
+				context->rectangle (self.x0, self.y0, self.width(), self.height());
+			}
 
 		} else {
 
@@ -132,6 +154,10 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
 		context->stroke ();
 	}
 
+	if (_corner_radius) {
+		context->restore ();
+	}
+
 	render_children (area, context);
 }
 
@@ -287,3 +313,13 @@ Rectangle::size_allocate (Rect const & r)
 		set (r);
 	}
 }
+
+void
+Rectangle::set_corner_radius (double r)
+{
+	/* note: this does not change the bounding box */
+
+	begin_change ();
+	_corner_radius = r;
+	end_change ();
+}