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livetrax/libs/canvas/line.cc

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/*
Copyright (C) 2011-2013 Paul Davis
Author: Carl Hetherington <cth@carlh.net>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <algorithm>
#include <cairomm/context.h>
#include "pbd/compose.h"
#include "canvas/line.h"
#include "canvas/types.h"
#include "canvas/debug.h"
#include "canvas/utils.h"
#include "canvas/canvas.h"
using namespace std;
using namespace ArdourCanvas;
Line::Line (Canvas* c)
: Item (c)
{
}
Line::Line (Item* parent)
: Item (parent)
{
}
void
Line::compute_bounding_box () const
{
Rect bbox;
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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);
bbox.y1 = max (_points[0].y, _points[1].y);
bbox = bbox.expand (0.5 + (_outline_width / 2));
_bounding_box = bbox;
_bounding_box_dirty = false;
}
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
*/
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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 ();
}
void
Line::set (Duple a, Duple b)
{
if (a != _points[0] || b != _points[1]) {
begin_change ();
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_points[0] = a;
_points[1] = b;
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_bounding_box_dirty = true;
end_change ();
}
}
void
Line::set_x (Coord x0, Coord x1)
{
if (x0 != _points[0].x || x1 != _points[1].x) {
begin_change ();
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_points[0].x = x0;
_points[1].x = x1;
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_bounding_box_dirty = true;
end_change ();
}
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}
void
Line::set_x0 (Coord x0)
{
if (x0 != _points[0].x) {
begin_change ();
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_points[0].x = x0;
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_bounding_box_dirty = true;
end_change ();
}
}
void
Line::set_y0 (Coord y0)
{
if (y0 != _points[0].y) {
begin_change ();
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_points[0].y = y0;
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_bounding_box_dirty = true;
end_change ();
}
DEBUG_TRACE (PBD::DEBUG::CanvasItemsDirtied, "canvas item dirty: line change\n");
}
void
Line::set_x1 (Coord x1)
{
if (x1 != _points[1].x) {
begin_change ();
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_points[1].x = x1;
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_bounding_box_dirty = true;
end_change ();
}
}
void
Line::set_y1 (Coord y1)
{
if (y1 != _points[1].y) {
begin_change ();
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_points[1].y = y1;
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_bounding_box_dirty = true;
end_change ();
}
}
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;
}