svg-path.cpp revision 6b15695578f07a3f72c4c9475c1a261a3021472a
#define __SP_SVG_PARSE_C__
/*
svg-path.c: Parse SVG path element data into bezier path.
Copyright (C) 2000 Eazel, Inc.
Copyright (C) 2000 Lauris Kaplinski
Copyright (C) 2001 Ximian, Inc.
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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
Authors:
Raph Levien <raph@artofcode.com>
Lauris Kaplinski <lauris@ximian.com>
*/
#include <cassert>
#include <glib/gmem.h>
#include <glib/gmessages.h>
#include <glib/gstrfuncs.h>
#include "libnr/n-art-bpath.h"
#include "gnome-canvas-bpath-util.h"
#include "stringstream.h"
/* This module parses an SVG path element into an RsvgBpathDef.
At present, there is no support for <marker> or any other contextual
information from the SVG file. The API will need to change rather
significantly to support these.
Reference: SVG working draft 3 March 2000, section 8.
*/
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif /* M_PI */
/* We are lazy ;-) (Lauris) */
#define rsvg_bpath_def_new gnome_canvas_bpath_def_new
#define rsvg_bpath_def_moveto gnome_canvas_bpath_def_moveto
#define rsvg_bpath_def_lineto gnome_canvas_bpath_def_lineto
#define rsvg_bpath_def_curveto gnome_canvas_bpath_def_curveto
#define rsvg_bpath_def_closepath gnome_canvas_bpath_def_closepath
struct RSVGParsePathCtx {
GnomeCanvasBpathDef *bpath;
double cpx, cpy; /* current point */
double rpx, rpy; /* reflection point (for 's' and 't' commands) */
double spx, spy; /* beginning of current subpath point */
char cmd; /* current command (lowercase) */
int param; /* parameter number */
gboolean rel; /* true if relative coords */
double params[7]; /* parameters that have been parsed */
};
static void rsvg_path_arc_segment(RSVGParsePathCtx *ctx,
double xc, double yc,
double th0, double th1,
double rx, double ry, double x_axis_rotation)
{
double sin_th, cos_th;
double a00, a01, a10, a11;
double x1, y1, x2, y2, x3, y3;
double t;
double th_half;
sin_th = sin (x_axis_rotation * (M_PI / 180.0));
cos_th = cos (x_axis_rotation * (M_PI / 180.0));
/* inverse transform compared with rsvg_path_arc */
a00 = cos_th * rx;
a01 = -sin_th * ry;
a10 = sin_th * rx;
a11 = cos_th * ry;
th_half = 0.5 * (th1 - th0);
t = (8.0 / 3.0) * sin(th_half * 0.5) * sin(th_half * 0.5) / sin(th_half);
x1 = xc + cos (th0) - t * sin (th0);
y1 = yc + sin (th0) + t * cos (th0);
x3 = xc + cos (th1);
y3 = yc + sin (th1);
x2 = x3 + t * sin (th1);
y2 = y3 - t * cos (th1);
rsvg_bpath_def_curveto(ctx->bpath,
a00 * x1 + a01 * y1, a10 * x1 + a11 * y1,
a00 * x2 + a01 * y2, a10 * x2 + a11 * y2,
a00 * x3 + a01 * y3, a10 * x3 + a11 * y3);
}
/**
* rsvg_path_arc: Add an RSVG arc to the path context.
* @ctx: Path context.
* @rx: Radius in x direction (before rotation).
* @ry: Radius in y direction (before rotation).
* @x_axis_rotation: Rotation angle for axes.
* @large_arc_flag: 0 for arc length <= 180, 1 for arc >= 180.
* @sweep: 0 for "negative angle", 1 for "positive angle".
* @x: New x coordinate.
* @y: New y coordinate.
*
**/
static void rsvg_path_arc (RSVGParsePathCtx *ctx,
double rx, double ry, double x_axis_rotation,
int large_arc_flag, int sweep_flag,
double x, double y)
{
double sin_th, cos_th;
double a00, a01, a10, a11;
double x0, y0, x1, y1, xc, yc;
double d, sfactor, sfactor_sq;
double th0, th1, th_arc;
double px, py, pl;
int i, n_segs;
sin_th = sin (x_axis_rotation * (M_PI / 180.0));
cos_th = cos (x_axis_rotation * (M_PI / 180.0));
/*
Correction of out-of-range radii as described in Appendix F.6.6:
1. Ensure radii are non-zero (Done?).
2. Ensure that radii are positive.
3. Ensure that radii are large enough.
*/
if(rx < 0.0) rx = -rx;
if(ry < 0.0) ry = -ry;
px = cos_th * (ctx->cpx - x) * 0.5 + sin_th * (ctx->cpy - y) * 0.5;
py = cos_th * (ctx->cpy - y) * 0.5 - sin_th * (ctx->cpx - x) * 0.5;
pl = (px * px) / (rx * rx) + (py * py) / (ry * ry);
if(pl > 1.0)
{
pl = sqrt(pl);
rx *= pl;
ry *= pl;
}
/* Proceed with computations as described in Appendix F.6.5 */
a00 = cos_th / rx;
a01 = sin_th / rx;
a10 = -sin_th / ry;
a11 = cos_th / ry;
x0 = a00 * ctx->cpx + a01 * ctx->cpy;
y0 = a10 * ctx->cpx + a11 * ctx->cpy;
x1 = a00 * x + a01 * y;
y1 = a10 * x + a11 * y;
/* (x0, y0) is current point in transformed coordinate space.
(x1, y1) is new point in transformed coordinate space.
The arc fits a unit-radius circle in this space.
*/
d = (x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0);
sfactor_sq = 1.0 / d - 0.25;
if (sfactor_sq < 0) sfactor_sq = 0;
sfactor = sqrt (sfactor_sq);
if (sweep_flag == large_arc_flag) sfactor = -sfactor;
xc = 0.5 * (x0 + x1) - sfactor * (y1 - y0);
yc = 0.5 * (y0 + y1) + sfactor * (x1 - x0);
/* (xc, yc) is center of the circle. */
th0 = atan2 (y0 - yc, x0 - xc);
th1 = atan2 (y1 - yc, x1 - xc);
th_arc = th1 - th0;
if (th_arc < 0 && sweep_flag)
th_arc += 2 * M_PI;
else if (th_arc > 0 && !sweep_flag)
th_arc -= 2 * M_PI;
n_segs = (int) ceil (fabs (th_arc / (M_PI * 0.5 + 0.001)));
for (i = 0; i < n_segs; i++) {
rsvg_path_arc_segment(ctx, xc, yc,
th0 + i * th_arc / n_segs,
th0 + (i + 1) * th_arc / n_segs,
rx, ry, x_axis_rotation);
}
ctx->cpx = x;
ctx->cpy = y;
}
/* supply defaults for missing parameters, assuming relative coordinates
are to be interpreted as x,y */
static void rsvg_parse_path_default_xy(RSVGParsePathCtx *ctx, int n_params)
{
int i;
if (ctx->rel) {
for (i = ctx->param; i < n_params; i++) {
if (i > 2)
ctx->params[i] = ctx->params[i - 2];
else if (i == 1)
ctx->params[i] = ctx->cpy;
else if (i == 0)
/* we shouldn't get here (usually ctx->param > 0 as
precondition) */
ctx->params[i] = ctx->cpx;
}
} else {
for (i = ctx->param; i < n_params; i++) {
ctx->params[i] = 0.0;
}
}
}
static void rsvg_parse_path_do_cmd(RSVGParsePathCtx *ctx, gboolean final)
{
double x1, y1, x2, y2, x3, y3;
#ifdef VERBOSE
int i;
g_print ("parse_path %c:", ctx->cmd);
for (i = 0; i < ctx->param; i++) {
g_print(" %f", ctx->params[i]);
}
g_print (final ? ".\n" : "\n");
#endif
switch (ctx->cmd) {
case 'm':
/* moveto */
if (ctx->param == 2
|| final)
{
rsvg_parse_path_default_xy (ctx, 2);
#ifdef VERBOSE
g_print ("'m' moveto %g,%g\n",
ctx->params[0], ctx->params[1]);
#endif
rsvg_bpath_def_moveto (ctx->bpath,
ctx->params[0], ctx->params[1]);
ctx->cpx = ctx->rpx = ctx->spx = ctx->params[0];
ctx->cpy = ctx->rpy = ctx->spy = ctx->params[1];
ctx->param = 0;
ctx->cmd = 'l';
}
break;
case 'l':
/* lineto */
if (ctx->param == 2
|| final)
{
rsvg_parse_path_default_xy (ctx, 2);
#ifdef VERBOSE
g_print ("'l' lineto %g,%g\n",
ctx->params[0], ctx->params[1]);
#endif
rsvg_bpath_def_lineto (ctx->bpath,
ctx->params[0], ctx->params[1]);
ctx->cpx = ctx->rpx = ctx->params[0];
ctx->cpy = ctx->rpy = ctx->params[1];
ctx->param = 0;
}
break;
case 'c':
/* curveto */
if ( ( ctx->param == 6 )
|| final )
{
rsvg_parse_path_default_xy (ctx, 6);
x1 = ctx->params[0];
y1 = ctx->params[1];
x2 = ctx->params[2];
y2 = ctx->params[3];
x3 = ctx->params[4];
y3 = ctx->params[5];
#ifdef VERBOSE
g_print ("'c' curveto %g,%g %g,%g, %g,%g\n",
x1, y1, x2, y2, x3, y3);
#endif
rsvg_bpath_def_curveto (ctx->bpath,
x1, y1, x2, y2, x3, y3);
ctx->rpx = x2;
ctx->rpy = y2;
ctx->cpx = x3;
ctx->cpy = y3;
ctx->param = 0;
}
break;
case 's':
/* smooth curveto */
if ( ( ctx->param == 4 )
|| final )
{
rsvg_parse_path_default_xy (ctx, 4);
x1 = 2 * ctx->cpx - ctx->rpx;
y1 = 2 * ctx->cpy - ctx->rpy;
x2 = ctx->params[0];
y2 = ctx->params[1];
x3 = ctx->params[2];
y3 = ctx->params[3];
#ifdef VERBOSE
g_print ("'s' curveto %g,%g %g,%g, %g,%g\n",
x1, y1, x2, y2, x3, y3);
#endif
rsvg_bpath_def_curveto (ctx->bpath,
x1, y1, x2, y2, x3, y3);
ctx->rpx = x2;
ctx->rpy = y2;
ctx->cpx = x3;
ctx->cpy = y3;
ctx->param = 0;
}
break;
case 'h':
/* horizontal lineto */
if (ctx->param == 1) {
#ifdef VERBOSE
g_print ("'h' lineto %g,%g\n",
ctx->params[0], ctx->cpy);
#endif
rsvg_bpath_def_lineto (ctx->bpath,
ctx->params[0], ctx->cpy);
ctx->cpx = ctx->rpx = ctx->params[0];
ctx->param = 0;
}
break;
case 'v':
/* vertical lineto */
if (ctx->param == 1) {
#ifdef VERBOSE
g_print ("'v' lineto %g,%g\n",
ctx->cpx, ctx->params[0]);
#endif
rsvg_bpath_def_lineto (ctx->bpath,
ctx->cpx, ctx->params[0]);
ctx->cpy = ctx->rpy = ctx->params[0];
ctx->param = 0;
}
break;
case 'q':
/* quadratic bezier curveto */
/* non-normative reference:
http://www.icce.rug.nl/erikjan/bluefuzz/beziers/beziers/beziers.html
*/
if (ctx->param == 4 || final)
{
rsvg_parse_path_default_xy (ctx, 4);
/* raise quadratic bezier to cubic */
x1 = (ctx->cpx + 2 * ctx->params[0]) * (1.0 / 3.0);
y1 = (ctx->cpy + 2 * ctx->params[1]) * (1.0 / 3.0);
x3 = ctx->params[2];
y3 = ctx->params[3];
x2 = (x3 + 2 * ctx->params[0]) * (1.0 / 3.0);
y2 = (y3 + 2 * ctx->params[1]) * (1.0 / 3.0);
#ifdef VERBOSE
g_print("'q' curveto %g,%g %g,%g, %g,%g\n",
x1, y1, x2, y2, x3, y3);
#endif
rsvg_bpath_def_curveto(ctx->bpath,
x1, y1, x2, y2, x3, y3);
ctx->rpx = ctx->params[0];
ctx->rpy = ctx->params[1];
ctx->cpx = x3;
ctx->cpy = y3;
ctx->param = 0;
}
break;
case 't':
/* Truetype quadratic bezier curveto */
if (ctx->param == 2 || final) {
double xc, yc; /* quadratic control point */
xc = 2 * ctx->cpx - ctx->rpx;
yc = 2 * ctx->cpy - ctx->rpy;
/* generate a quadratic bezier with control point = xc, yc */
x1 = (ctx->cpx + 2 * xc) * (1.0 / 3.0);
y1 = (ctx->cpy + 2 * yc) * (1.0 / 3.0);
x3 = ctx->params[0];
y3 = ctx->params[1];
x2 = (x3 + 2 * xc) * (1.0 / 3.0);
y2 = (y3 + 2 * yc) * (1.0 / 3.0);
#ifdef VERBOSE
g_print ("'t' curveto %g,%g %g,%g, %g,%g\n",
x1, y1, x2, y2, x3, y3);
#endif
rsvg_bpath_def_curveto (ctx->bpath,
x1, y1, x2, y2, x3, y3);
ctx->rpx = xc;
ctx->rpy = yc;
ctx->cpx = x3;
ctx->cpy = y3;
ctx->param = 0;
} else if (final) {
if (ctx->param > 2) {
rsvg_parse_path_default_xy(ctx, 4);
/* raise quadratic bezier to cubic */
x1 = (ctx->cpx + 2 * ctx->params[0]) * (1.0 / 3.0);
y1 = (ctx->cpy + 2 * ctx->params[1]) * (1.0 / 3.0);
x3 = ctx->params[2];
y3 = ctx->params[3];
x2 = (x3 + 2 * ctx->params[0]) * (1.0 / 3.0);
y2 = (y3 + 2 * ctx->params[1]) * (1.0 / 3.0);
#ifdef VERBOSE
g_print ("'t' curveto %g,%g %g,%g, %g,%g\n",
x1, y1, x2, y2, x3, y3);
#endif
rsvg_bpath_def_curveto (ctx->bpath,
x1, y1, x2, y2, x3, y3);
ctx->rpx = x2;
ctx->rpy = y2;
ctx->cpx = x3;
ctx->cpy = y3;
} else {
rsvg_parse_path_default_xy(ctx, 2);
#ifdef VERBOSE
g_print ("'t' lineto %g,%g\n",
ctx->params[0], ctx->params[1]);
#endif
rsvg_bpath_def_lineto(ctx->bpath,
ctx->params[0], ctx->params[1]);
ctx->cpx = ctx->rpx = ctx->params[0];
ctx->cpy = ctx->rpy = ctx->params[1];
}
ctx->param = 0;
}
break;
case 'a':
if (ctx->param == 7 || final)
{
rsvg_path_arc(ctx,
ctx->params[0], ctx->params[1], ctx->params[2],
(int) ctx->params[3], (int) ctx->params[4],
ctx->params[5], ctx->params[6]);
ctx->param = 0;
}
break;
default:
ctx->param = 0;
}
}
static void rsvg_parse_path_data(RSVGParsePathCtx *ctx, const char *data)
{
int i = 0;
double val = 0;
char c = 0;
gboolean in_num = FALSE;
gboolean in_frac = FALSE;
gboolean in_exp = FALSE;
gboolean exp_wait_sign = FALSE;
int sign = 0;
int exp = 0;
int exp_sign = 0;
double frac = 0.0;
/* fixme: Do better error processing: e.g. at least stop parsing as soon as we find an error.
* At some point we'll need to do all of
* http://www.w3.org/TR/SVG11/implnote.html#ErrorProcessing.
*/
for (i = 0; ; i++)
{
c = data[i];
if (c >= '0' && c <= '9')
{
/* digit */
if (in_num)
{
if (in_exp)
{
exp = (exp * 10) + c - '0';
exp_wait_sign = FALSE;
}
else if (in_frac)
val += (frac *= 0.1) * (c - '0');
else
val = (val * 10) + c - '0';
}
else
{
in_num = TRUE;
assert(!in_frac && !in_exp);
exp = 0;
exp_sign = 1;
exp_wait_sign = FALSE;
val = c - '0';
sign = 1;
}
}
else if (c == '.' && !(in_frac || in_exp))
{
if (!in_num)
{
in_num = TRUE;
assert(!in_exp);
exp = 0;
exp_sign = 1;
exp_wait_sign = FALSE;
val = 0;
sign = 1;
}
in_frac = TRUE;
frac = 1;
}
else if ((c == 'E' || c == 'e') && in_num)
{
/* fixme: Should we add `&& !in_exp' to the above condition?
* It looks like the current code will parse `1e3e4' (as 1e4). */
in_exp = TRUE;
exp_wait_sign = TRUE;
exp = 0;
exp_sign = 1;
}
else if ((c == '+' || c == '-') && in_exp)
{
exp_sign = c == '+' ? 1 : -1;
}
else if (in_num)
{
/* end of number */
val *= sign * pow (10, exp_sign * exp);
if (ctx->rel)
{
/* Handle relative coordinates. This switch statement attempts
to determine _what_ the coords are relative to. This is
underspecified in the 12 Apr working draft. */
switch (ctx->cmd)
{
case 'l':
case 'm':
case 'c':
case 's':
case 'q':
case 't':
if ( ctx->param & 1 ) {
val += ctx->cpy; /* odd param, y */
} else {
val += ctx->cpx; /* even param, x */
}
break;
case 'a':
/* rule: sixth and seventh are x and y, rest are not
relative */
if (ctx->param == 5)
val += ctx->cpx;
else if (ctx->param == 6)
val += ctx->cpy;
break;
case 'h':
/* rule: x-relative */
val += ctx->cpx;
break;
case 'v':
/* rule: y-relative */
val += ctx->cpy;
break;
}
}
ctx->params[ctx->param++] = val;
rsvg_parse_path_do_cmd (ctx, FALSE);
if (c=='.') {
in_num = TRUE;
val = 0;
in_frac = TRUE;
in_exp = FALSE;
frac = 1;
}
else {
in_num = FALSE;
in_frac = FALSE;
in_exp = FALSE;
}
}
if (c == '\0')
break;
else if ((c == '+' || c == '-') && !exp_wait_sign)
{
sign = c == '+' ? 1 : -1;;
val = 0;
in_num = TRUE;
in_frac = FALSE;
in_exp = FALSE;
exp = 0;
exp_sign = 1;
exp_wait_sign = FALSE;
}
else if (c == 'z' || c == 'Z')
{
if (ctx->param)
rsvg_parse_path_do_cmd (ctx, TRUE);
rsvg_bpath_def_closepath (ctx->bpath);
ctx->cmd = 'm';
ctx->params[0] = ctx->cpx = ctx->rpx = ctx->spx;
ctx->params[1] = ctx->cpy = ctx->rpy = ctx->spy;
ctx->param = 2;
}
else if (c >= 'A' && c <= 'Z' && c != 'E')
{
if (ctx->param)
rsvg_parse_path_do_cmd (ctx, TRUE);
ctx->cmd = c + 'a' - 'A';
ctx->rel = FALSE;
}
else if (c >= 'a' && c <= 'z' && c != 'e')
{
if (ctx->param)
rsvg_parse_path_do_cmd (ctx, TRUE);
ctx->cmd = c;
ctx->rel = TRUE;
}
/* else c _should_ be whitespace or , */
}
}
NArtBpath *sp_svg_read_path(gchar const *str)
{
RSVGParsePathCtx ctx;
NArtBpath *bpath;
ctx.bpath = gnome_canvas_bpath_def_new ();
ctx.cpx = 0.0;
ctx.cpy = 0.0;
ctx.cmd = 0;
ctx.param = 0;
rsvg_parse_path_data (&ctx, str);
if (ctx.param && ctx.cmd != 'm') {
rsvg_parse_path_do_cmd (&ctx, TRUE);
}
gnome_canvas_bpath_def_art_finish (ctx.bpath);
bpath = g_new (NArtBpath, ctx.bpath->n_bpath);
memcpy (bpath, ctx.bpath->bpath, ctx.bpath->n_bpath * sizeof (NArtBpath));
g_assert ((bpath + ctx.bpath->n_bpath - 1)->code == NR_END);
gnome_canvas_bpath_def_unref (ctx.bpath);
return bpath;
}
gchar *sp_svg_write_path(NArtBpath const *bpath)
{
Inkscape::SVGOStringStream os;
bool closed=false;
g_return_val_if_fail (bpath != NULL, NULL);
for (int i = 0; bpath[i].code != NR_END; i++){
if (i) {
os << " ";
}
switch (bpath [i].code){
case NR_LINETO:
os << "L " << bpath[i].x3 << "," << bpath[i].y3;
break;
case NR_CURVETO:
os << "C " << bpath[i].x1 << "," << bpath[i].y1
<< " " << bpath[i].x2 << "," << bpath[i].y2
<< " " << bpath[i].x3 << "," << bpath[i].y3;
break;
case NR_MOVETO_OPEN:
case NR_MOVETO:
if (closed) {
os << "z ";
}
closed = ( bpath[i].code == NR_MOVETO );
os << "M " << bpath[i].x3 << "," << bpath[i].y3;
break;
default:
g_assert_not_reached ();
}
}
if (closed) {
os << " z ";
}
// std::string s = os.str();
// gchar *ret = g_strdup(s.c_str());
// delete (s);
// return ret;
return g_strdup (os.str().c_str());
}
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :