/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1998-2000 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* Basic constructors and operations for vector paths */
#include "config.h"
#include "art_vpath.h"
#include <math.h>
#include <stdlib.h>
#include "art_misc.h"
#include "art_rect.h"
/**
* art_vpath_add_point: Add point to vpath.
* @p_vpath: Where the pointer to the #ArtVpath structure is stored.
* @pn_points: Pointer to the number of points in *@p_vpath.
* @pn_points_max: Pointer to the number of points allocated.
* @code: The pathcode for the new point.
* @x: The X coordinate of the new point.
* @y: The Y coordinate of the new point.
*
* Adds a new point to *@p_vpath, reallocating and updating *@p_vpath
* and *@pn_points_max as necessary. *@pn_points is incremented.
*
* This routine always adds the point after all points already in the
* vpath. Thus, it should be called in the order the points are
* desired.
**/
void
art_vpath_add_point (ArtVpath **p_vpath, int *pn_points, int *pn_points_max,
ArtPathcode code, double x, double y)
{
int i;
i = (*pn_points)++;
if (i == *pn_points_max)
art_expand (*p_vpath, ArtVpath, *pn_points_max);
(*p_vpath)[i].code = code;
(*p_vpath)[i].x = x;
(*p_vpath)[i].y = y;
}
/* number of steps should really depend on radius. */
#define CIRCLE_STEPS 128
/**
* art_vpath_new_circle: Create a new circle.
* @x: X coordinate of center.
* @y: Y coordinate of center.
* @r: radius.
*
* Creates a new polygon closely approximating a circle with center
* (@x, @y) and radius @r. Currently, the number of points used in the
* approximation is fixed, but that will probably change.
*
* Return value: The newly created #ArtVpath.
**/
ArtVpath *
art_vpath_new_circle (double x, double y, double r)
{
int i;
ArtVpath *vec;
double theta;
vec = art_new (ArtVpath, CIRCLE_STEPS + 2);
for (i = 0; i < CIRCLE_STEPS + 1; i++)
{
vec[i].code = i ? ART_LINETO : ART_MOVETO;
theta = (i & (CIRCLE_STEPS - 1)) * (M_PI * 2.0 / CIRCLE_STEPS);
vec[i].x = x + r * cos (theta);
vec[i].y = y - r * sin (theta);
}
vec[i].code = ART_END;
return vec;
}
/**
* art_vpath_affine_transform: Affine transform a vpath.
* @src: Source vpath to transform.
* @matrix: Affine transform.
*
* Computes the affine transform of the vpath, using @matrix as the
* transform. @matrix is stored in the same format as PostScript, ie.
* x' = @matrix[0] * x + @matrix[2] * y + @matrix[4]
* y' = @matrix[1] * x + @matrix[3] * y + @matrix[5]
*
* Return value: the newly allocated vpath resulting from the transform.
**/
ArtVpath *
art_vpath_affine_transform (const ArtVpath *src, const double matrix[6])
{
int i;
int size;
ArtVpath *new;
double x, y;
for (i = 0; src[i].code != ART_END; i++);
size = i;
new = art_new (ArtVpath, size + 1);
for (i = 0; i < size; i++)
{
new[i].code = src[i].code;
x = src[i].x;
y = src[i].y;
new[i].x = matrix[0] * x + matrix[2] * y + matrix[4];
new[i].y = matrix[1] * x + matrix[3] * y + matrix[5];
}
new[i].code = ART_END;
return new;
}
/**
* art_vpath_bbox_drect: Determine bounding box of vpath.
* @vec: Source vpath.
* @drect: Where to store bounding box.
*
* Determines bounding box of @vec, and stores it in @drect.
**/
void
art_vpath_bbox_drect (const ArtVpath *vec, ArtDRect *drect)
{
int i;
double x0, y0, x1, y1;
if (vec[0].code == ART_END)
{
x0 = y0 = x1 = y1 = 0;
}
else
{
x0 = x1 = vec[0].x;
y0 = y1 = vec[0].y;
for (i = 1; vec[i].code != ART_END; i++)
{
if (vec[i].x < x0) x0 = vec[i].x;
if (vec[i].x > x1) x1 = vec[i].x;
if (vec[i].y < y0) y0 = vec[i].y;
if (vec[i].y > y1) y1 = vec[i].y;
}
}
drect->x0 = x0;
drect->y0 = y0;
drect->x1 = x1;
drect->y1 = y1;
}
/**
* art_vpath_bbox_irect: Determine integer bounding box of vpath.
* @vec: Source vpath.
* idrect: Where to store bounding box.
*
* Determines integer bounding box of @vec, and stores it in @irect.
**/
void
art_vpath_bbox_irect (const ArtVpath *vec, ArtIRect *irect)
{
ArtDRect drect;
art_vpath_bbox_drect (vec, &drect);
art_drect_to_irect (irect, &drect);
}
#define PERTURBATION 2e-3
/**
* art_vpath_perturb: Perturb each point in vpath by small random amount.
* @src: Source vpath.
*
* Perturbs each of the points by a small random amount. This is
* helpful for cheating in cases when algorithms haven't attained
* numerical stability yet.
*
* Return value: Newly allocated vpath containing perturbed @src.
**/
ArtVpath *
art_vpath_perturb (ArtVpath *src)
{
int i;
int size;
ArtVpath *new;
double x, y;
double x_start, y_start;
int open;
for (i = 0; src[i].code != ART_END; i++);
size = i;
new = art_new (ArtVpath, size + 1);
x_start = 0;
y_start = 0;
open = 0;
for (i = 0; i < size; i++)
{
new[i].code = src[i].code;
x = src[i].x + (PERTURBATION * rand ()) / RAND_MAX - PERTURBATION * 0.5;
y = src[i].y + (PERTURBATION * rand ()) / RAND_MAX - PERTURBATION * 0.5;
if (src[i].code == ART_MOVETO)
{
x_start = x;
y_start = y;
open = 0;
}
else if (src[i].code == ART_MOVETO_OPEN)
open = 1;
if (!open && (i + 1 == size || src[i + 1].code != ART_LINETO))
{
x = x_start;
y = y_start;
}
new[i].x = x;
new[i].y = y;
}
new[i].code = ART_END;
return new;
}
