ArdourCanvas::Line::covers() uses distance_to_segment_squared()
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@ -151,18 +151,47 @@ Line::set_y1 (Coord y1)
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bool
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bool
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Line::covers (Duple const & point) const
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Line::covers (Duple const & point) const
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{
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{
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Duple p = canvas_to_item (point);
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const Duple p = canvas_to_item (point);
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static const Distance threshold = 2.0;
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/* compute area of triangle computed by the two line points and the one
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/* this quick check works for vertical and horizontal lines, which are
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we are being asked about. If zero (within a given tolerance), the
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* common.
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points are co-linear and the argument is on the line.
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*/
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if (_points[0].x == _points[1].x) {
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/* line is vertical, just check x coordinate */
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return fabs (_points[0].x - p.x) <= threshold;
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}
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if (_points[0].y == _points[1].y) {
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/* line is horizontal, just check y coordinate */
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return fabs (_points[0].y - p.y) <= threshold;
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}
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Duple at;
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double t;
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Duple a (_points[0]);
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Duple b (_points[1]);
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const Rect visible (_canvas->visible_area());
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/*
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Clamp the line endpoints to the visible area of the canvas. If we do
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not do this, we have a line segment extending to COORD_MAX and our
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math goes wrong.
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*/
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*/
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double area = fabs (_points[0].x * (_points[0].y - p.y)) +
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a.x = min (a.x, visible.x1);
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(_points[1].x * (p.y - _points[0].y)) +
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a.y = min (a.y, visible.y1);
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(p.x * (_points[0].y - _points[1].y));
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b.x = min (b.x, visible.x1);
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b.y = min (b.y, visible.y1);
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if (area < 0.001) {
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double d = distance_to_segment_squared (p, a, b, t, at);
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if (t < 0.0 || t > 1.0) {
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return false;
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}
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if (d < threshold) {
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return true;
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return true;
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}
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}
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