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livetrax/libs/canvas/arc.cc
Paul Davis a1f69ee63b canvas: tweaks to Arc canvas item
Cairo uses 0 degrees to mean "east", so the "top" or "north" of
a circle is actually -90 degrees
2022-08-27 12:54:43 -06:00

174 lines
3.4 KiB
C++

/*
* Copyright (C) 2013-2015 Paul Davis <paul@linuxaudiosystems.com>
* Copyright (C) 2015-2017 Robin Gareus <robin@gareus.org>
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <cmath>
#include <algorithm>
#include <cairomm/context.h>
#include "pbd/compose.h"
#include "canvas/circle.h"
#include "canvas/types.h"
#include "canvas/debug.h"
#include "canvas/canvas.h"
using namespace std;
using namespace ArdourCanvas;
Arc::Arc (Canvas* c)
: Item (c)
, _radius (0.0)
, _arc_degrees (0.0)
, _start_degrees (0.0)
{
}
Arc::Arc (Item* parent)
: Item (parent)
, _radius (0.0)
, _arc_degrees (0.0)
, _start_degrees (0.0)
{
}
void
Arc::compute_bounding_box () const
{
Rect bbox;
/* this could be smaller in the case of small _arc values
but I can't be bothered to optimize it.
*/
bbox.x0 = _center.x - _radius;
bbox.y0 = _center.y - _radius;
bbox.x1 = _center.x + _radius;
bbox.y1 = _center.y + _radius;
bbox = bbox.expand (0.5 + (_outline_width / 2));
_bounding_box = bbox;
set_bbox_clean ();
}
void
Arc::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
{
if (_radius <= 0.0 || (!fill() && !outline())) {
return;
}
Duple c = item_to_window (Duple (_center.x, _center.y));
if (_arc_degrees != _start_degrees) {
context->arc (c.x, c.y, _radius, _start_degrees * (M_PI/180.0), _arc_degrees * (M_PI/180.0));
if (fill()) {
setup_fill_context (context);
if (outline()) {
context->fill_preserve ();
} else {
context->fill ();
}
}
if (outline()) {
setup_outline_context (context);
context->stroke ();
}
}
render_children (area, context);
}
void
Arc::set_center (Duple const & c)
{
begin_change ();
_center = c;
set_bbox_dirty ();
end_change ();
}
void
Arc::set_radius (Coord r)
{
begin_change ();
_radius = r;
set_bbox_dirty ();
end_change ();
}
void
Arc::set_arc (double deg)
{
begin_change ();
_arc_degrees = deg;
set_bbox_dirty ();
end_change ();
}
void
Arc::set_start (double deg)
{
begin_change ();
_start_degrees = deg;
set_bbox_dirty ();
end_change ();
}
bool
Arc::covers (Duple const & point) const
{
Duple p = window_to_item (point);
double angle_degs = atan (p.y/p.x) * 2.0 * M_PI;
double radius = sqrt (p.x * p.x + p.y * p.y);
return (angle_degs >= _start_degrees) &&
(angle_degs <= (_start_degrees + _arc_degrees)) &&
(radius < _radius);
}
void
Arc::_size_allocate (Rect const & r)
{
Item::_size_allocate (r);
/* This is an arc - some section of a circle, so any difference between
* height and width cannot change what is drawn. Pick width arbitrarily
* as the "key" dimension
*/
_radius = min (r.width(),r.height()) / 2.0;
_center = Duple ((r.width()/2.), (r.height() /2.));
set_bbox_dirty ();
}