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/* 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
#ifdef _HAVE_PROTOS
_API_fcircle (R___(Plotter *_plotter) double x, double y, double r)
#else
_API_fcircle (R___(_plotter) x, y, r)
S___(Plotter *_plotter;)
double x, y, r;
#endif
{
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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