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/* This file is part of the GNU plotutils package. Copyright (C) 1995,
1996, 1997, 1998, 1999, 2000, 2005, 2008, Free Software Foundation, Inc.
The GNU plotutils package is free software. You may 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, or (at your
option) any later version.
The GNU plotutils package 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 the GNU plotutils package; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 51 Franklin St., Fifth Floor,
Boston, MA 02110-1301, USA. */
/* This file contains the circle method, which is a standard part of
libplot. It draws an object: a circle with center x,y and radius r.
Circles are one of the three types of primitive closed path that libplot
supports, along with boxes and ellipses. */
/* Most Plotters obviously require that the map from the user frame to the
device frame be uniform, in order to draw a circle as a primitive (if it
isn't, what results will be an ellipse). The constraints on the user
frame -> device frame map (e.g., it must be uniform) are specified by
the internal `allowed_circle_scaling' parameter, which this code checks. */
#include "sys-defines.h"
#include "extern.h"
int
_API_fcircle (R___(Plotter *_plotter) double x, double y, double r)
{
if (!_plotter->data->open)
{
_plotter->error (R___(_plotter)
"fcircle: invalid operation");
return -1;
}
/* If a simple path is under construction (so that endsubpath() must not
have been invoked), flush out the whole compound path. (It may
include other, previously drawn simple paths.) */
if (_plotter->drawstate->path)
_API_endpath (S___(_plotter));
if (!_plotter->drawstate->points_are_connected)
/* line type is `disconnected', so do nothing (libplot convention) */
{
}
else
/* general case */
{
plPoint pc;
bool clockwise;
/* begin a new path */
_plotter->drawstate->path = _new_plPath ();
/* place circle in path buffer */
pc.x = x;
pc.y = y;
clockwise = _plotter->drawstate->orientation < 0 ? true : false;
if ((_plotter->data->allowed_circle_scaling == AS_ANY)
||
(_plotter->data->allowed_circle_scaling == AS_UNIFORM
&& _plotter->drawstate->transform.uniform))
/* place circle as a primitive, since this Plotter supports
drawing circles as primitives */
_add_circle (_plotter->drawstate->path,
pc, r, clockwise);
else if ((_plotter->data->allowed_ellipse_scaling == AS_ANY)
||
(_plotter->data->allowed_ellipse_scaling == AS_AXES_PRESERVED
&& _plotter->drawstate->transform.axes_preserved))
/* place circle as an ellipse, since this Plotter supports drawing
ellipses as primitives */
_add_ellipse (_plotter->drawstate->path,
pc, r, r, 0.0, clockwise);
else if (_plotter->data->allowed_ellarc_scaling == AS_ANY
|| (_plotter->data->allowed_ellarc_scaling == AS_AXES_PRESERVED
&& _plotter->drawstate->transform.axes_preserved))
/* draw circle by placing four elliptical arcs into path buffer
(allowed since this Plotter supports elliptical arcs) */
_add_circle_as_ellarcs (_plotter->drawstate->path,
pc, r, clockwise);
else if (_plotter->data->allowed_cubic_scaling == AS_ANY)
/* draw circle by placing four cubic Beziers into path buffer
(allowed since this Plotter supports cubic Beziers) */
_add_circle_as_bezier3s (_plotter->drawstate->path,
pc, r, clockwise);
else
/* draw a polygonal approximation to the circle */
_add_circle_as_lines (_plotter->drawstate->path,
pc, r, clockwise);
if (_plotter->drawstate->path->type == PATH_SEGMENT_LIST)
/* pass all the newly added segments to the Plotter-specific
function maybe_paint_segments(), since some Plotters plot paths
in real time, i.e., prepaint them, rather than waiting until
endpath() is called */
_plotter->maybe_prepaint_segments (R___(_plotter) 0);
}
/* move to center (libplot convention) */
_plotter->drawstate->pos.x = x;
_plotter->drawstate->pos.y = y;
return 0;
}
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