X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fcanvas%2Fline.cc;h=49d2987e3d6b1c4a9adb5a59198ffcc25cd1e1a0;hb=c8c6bca6587450ff64303dbc994a4cd28d6ce7aa;hp=b6a802b8df7ce4fce9977ecdca36f8f87107563b;hpb=77f5f4c4bf9074d953a1653658c8f96f38ae258c;p=ardour.git

diff --git a/libs/canvas/line.cc b/libs/canvas/line.cc
index b6a802b8df..49d2987e3d 100644
--- a/libs/canvas/line.cc
+++ b/libs/canvas/line.cc
@@ -29,18 +29,21 @@
 using namespace std;
 using namespace ArdourCanvas;
 
-Line::Line (Group* parent)
-	: Item (parent)
-	, Outline (parent)
+Line::Line (Canvas* c)
+	: Item (c)
 {
+}
 
+Line::Line (Item* parent)
+	: Item (parent)
+{
 }
 
 void
 Line::compute_bounding_box () const
 {
 	Rect bbox;
-	
+
 	bbox.x0 = min (_points[0].x, _points[1].x);
 	bbox.y0 = min (_points[0].y, _points[1].y);
 	bbox.x1 = max (_points[0].x, _points[1].x);
@@ -56,8 +59,19 @@ void
 Line::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
 {
 	setup_outline_context (context);
+
 	Duple p0 = item_to_window (Duple (_points[0].x, _points[0].y));
 	Duple p1 = item_to_window (Duple (_points[1].x, _points[1].y));
+
+	if (_outline_width <= 1.0) {
+		/* See Cairo FAQ on single pixel lines to understand why we add 0.5
+		 */
+
+		const Duple half_a_pixel (0.5, 0.5);
+		p0 = p0.translate (half_a_pixel);
+		p1 = p1.translate (half_a_pixel);
+	}
+
 	context->move_to (p0.x, p0.y);
 	context->line_to (p1.x, p1.y);
 	context->stroke ();
@@ -66,53 +80,55 @@ Line::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) cons
 void
 Line::set (Duple a, Duple b)
 {
-	begin_change ();
-
-	_points[0] = a;
-	_points[1] = b;
+	if (a != _points[0] || b != _points[1]) {
+		begin_change ();
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_points[0] = a;
+		_points[1] = b;
 
-	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
+		_bounding_box_dirty = true;
+		end_change ();
+	}
 }
 
 void
 Line::set_x (Coord x0, Coord x1)
 {
-	begin_change ();
-	
-	_points[0].x = x0;
-	_points[1].x = x1;
+	if (x0 != _points[0].x || x1 != _points[1].x) {
+		begin_change ();
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_points[0].x = x0;
+		_points[1].x = x1;
 
-	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
-}	
+		_bounding_box_dirty = true;
+		end_change ();
+	}
+}
 
 void
 Line::set_x0 (Coord x0)
 {
-	begin_change ();
-	
-	_points[0].x = x0;
+	if (x0 != _points[0].x) {
+		begin_change ();
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_points[0].x = x0;
 
-	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
+		_bounding_box_dirty = true;
+		end_change ();
+	}
 }
 
 void
 Line::set_y0 (Coord y0)
 {
-	begin_change ();
+	if (y0 != _points[0].y) {
+		begin_change ();
 
-	_points[0].y = y0;
+		_points[0].y = y0;
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_bounding_box_dirty = true;
+		end_change ();
+	}
 
 	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
 }
@@ -120,25 +136,75 @@ Line::set_y0 (Coord y0)
 void
 Line::set_x1 (Coord x1)
 {
-	begin_change ();
-
-	_points[1].x = x1;
+	if (x1 != _points[1].x) {
+		begin_change ();
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_points[1].x = x1;
 
-	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
+		_bounding_box_dirty = true;
+		end_change ();
+	}
 }
 
 void
 Line::set_y1 (Coord y1)
 {
-	begin_change ();
+	if (y1 != _points[1].y) {
+		begin_change ();
 
-	_points[1].y = y1;
+		_points[1].y = y1;
 
-	_bounding_box_dirty = true;
-	end_change ();
+		_bounding_box_dirty = true;
+		end_change ();
+	}
+}
 
-	DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
+bool
+Line::covers (Duple const & point) const
+{
+	const Duple p = window_to_item (point);
+	static const Distance threshold = 2.0;
+
+	/* this quick check works for vertical and horizontal lines, which are
+	 * common.
+	 */
+
+	if (_points[0].x == _points[1].x) {
+		/* line is vertical, just check x coordinate */
+		return fabs (_points[0].x - p.x) <= threshold;
+	}
+
+	if (_points[0].y == _points[1].y) {
+		/* line is horizontal, just check y coordinate */
+		return fabs (_points[0].y - p.y) <= threshold;
+	}
+
+	Duple at;
+	double t;
+	Duple a (_points[0]);
+	Duple b (_points[1]);
+	const Rect visible (window_to_item (_canvas->visible_area()));
+
+	/*
+	   Clamp the line endpoints to the visible area of the canvas. If we do
+	   not do this, we have a line segment extending to COORD_MAX and our
+	   math goes wrong.
+	*/
+
+	a.x = min (a.x, visible.x1);
+	a.y = min (a.y, visible.y1);
+	b.x = min (b.x, visible.x1);
+	b.y = min (b.y, visible.y1);
+
+	double d = distance_to_segment_squared (p, a, b, t, at);
+
+	if (t < 0.0 || t > 1.0) {
+		return false;
+	}
+
+	if (d < threshold) {
+		return true;
+	}
+
+	return false;
 }