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livetrax/libs/canvas/polygon.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 "canvas/polygon.h"
using namespace ArdourCanvas;
Polygon::Polygon (Group* parent)
: Item (parent)
, PolyItem (parent)
, Fill (parent)
, multiple (0)
, constant (0)
, cached_size (0)
{
}
Polygon::~Polygon ()
{
delete [] multiple;
delete [] constant;
}
void
Polygon::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
{
if (_outline) {
setup_outline_context (context);
render_path (area, context);
if (!_points.empty ()) {
/* close path */
Duple p = item_to_window (Duple (_points.front().x, _points.front().y));
context->move_to (p.x, p.y);
}
context->stroke_preserve ();
}
if (_fill) {
setup_fill_context (context);
context->fill ();
}
}
void
Polygon::cache_shape_computation () const
{
Points::size_type npoints = _points.size();
if (npoints == 0) {
return;
}
Points::size_type i;
Points::size_type j = npoints -1;
if (cached_size < npoints) {
cached_size = npoints;
delete [] multiple;
multiple = new float[cached_size];
delete [] constant;
constant = new float[cached_size];
}
for (i = 0; i < npoints; i++) {
if (_points[j].y == _points[i].y) {
constant[i] = _points[i].x;
multiple[i] = 0;
} else {
constant[i] = _points[i].x-(_points[i].y*_points[j].x)/(_points[j].y-_points[i].y)+(_points[i].y*_points[i].x)/(_points[j].y-_points[i].y);
multiple[i] = (_points[j].x-_points[i].x)/(_points[j].y-_points[i].y);
}
j = i;
}
}
bool
Polygon::covers (Duple const & point) const
{
Duple p = canvas_to_item (point);
Points::size_type npoints = _points.size();
if (npoints == 0) {
return false;
}
Points::size_type i;
Points::size_type j = npoints -1;
bool oddNodes = false;
if (_bounding_box_dirty) {
compute_bounding_box ();
}
for (i = 0; i < npoints; i++) {
if (((_points[i].y < p.y && _points[j].y >= p.y) || (_points[j].y < p.y && _points[i].y >= p.y))) {
oddNodes ^= (p.y * multiple[i] + constant[i] < p.x);
}
j = i;
}
return oddNodes;
}
void
Polygon::compute_bounding_box () const
{
PolyItem::compute_bounding_box ();
cache_shape_computation ();
}