/* 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.
*/
#include "config.h"
#include "art_uta_vpath.h"
#include <math.h>
#include "art_misc.h"
#include "art_vpath.h"
#include "art_uta.h"
#ifndef MAX
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#endif /* MAX */
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif /* MIN */
/**
* art_uta_add_line: Add a line to the uta.
* @uta: The uta to modify.
* @x0: X coordinate of line start point.
* @y0: Y coordinate of line start point.
* @x1: X coordinate of line end point.
* @y1: Y coordinate of line end point.
* @rbuf: Buffer containing first difference of winding number.
* @rbuf_rowstride: Rowstride of @rbuf.
*
* Add the line (@x0, @y0) - (@x1, @y1) to @uta, and also update the
* winding number buffer used for rendering the interior. @rbuf
* contains the first partial difference (in the X direction) of the
* winding number, measured in grid cells. Thus, each time that a line
* crosses a horizontal uta grid line, an entry of @rbuf is
* incremented if @y1 > @y0, decremented otherwise.
*
* Note that edge handling is fairly delicate. Please rtfs for
* details.
**/
void
art_uta_add_line (ArtUta *uta, double x0, double y0, double x1, double y1,
int *rbuf, int rbuf_rowstride)
{
int xmin, ymin;
double xmax, ymax;
int xmaxf, ymaxf;
int xmaxc, ymaxc;
int xt0, yt0;
int xt1, yt1;
int xf0, yf0;
int xf1, yf1;
int ix, ix1;
ArtUtaBbox bb;
xmin = floor (MIN(x0, x1));
xmax = MAX(x0, x1);
xmaxf = floor (xmax);
xmaxc = ceil (xmax);
ymin = floor (MIN(y0, y1));
ymax = MAX(y0, y1);
ymaxf = floor (ymax);
ymaxc = ceil (ymax);
xt0 = (xmin >> ART_UTILE_SHIFT) - uta->x0;
yt0 = (ymin >> ART_UTILE_SHIFT) - uta->y0;
xt1 = (xmaxf >> ART_UTILE_SHIFT) - uta->x0;
yt1 = (ymaxf >> ART_UTILE_SHIFT) - uta->y0;
if (xt0 == xt1 && yt0 == yt1)
{
/* entirely inside a microtile, this is easy! */
xf0 = xmin & (ART_UTILE_SIZE - 1);
yf0 = ymin & (ART_UTILE_SIZE - 1);
xf1 = (xmaxf & (ART_UTILE_SIZE - 1)) + xmaxc - xmaxf;
yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf;
ix = yt0 * uta->width + xt0;
bb = uta->utiles[ix];
if (bb == 0)
bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1);
else
bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0),
MIN(ART_UTA_BBOX_Y0(bb), yf0),
MAX(ART_UTA_BBOX_X1(bb), xf1),
MAX(ART_UTA_BBOX_Y1(bb), yf1));
uta->utiles[ix] = bb;
}
else
{
double dx, dy;
int sx, sy;
dx = x1 - x0;
dy = y1 - y0;
sx = dx > 0 ? 1 : dx < 0 ? -1 : 0;
sy = dy > 0 ? 1 : dy < 0 ? -1 : 0;
if (ymin == ymaxf)
{
/* special case horizontal (dx/dy slope would be infinite) */
xf0 = xmin & (ART_UTILE_SIZE - 1);
yf0 = ymin & (ART_UTILE_SIZE - 1);
xf1 = (xmaxf & (ART_UTILE_SIZE - 1)) + xmaxc - xmaxf;
yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf;
ix = yt0 * uta->width + xt0;
ix1 = yt0 * uta->width + xt1;
while (ix != ix1)
{
bb = uta->utiles[ix];
if (bb == 0)
bb = ART_UTA_BBOX_CONS(xf0, yf0, ART_UTILE_SIZE, yf1);
else
bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0),
MIN(ART_UTA_BBOX_Y0(bb), yf0),
ART_UTILE_SIZE,
MAX(ART_UTA_BBOX_Y1(bb), yf1));
uta->utiles[ix] = bb;
xf0 = 0;
ix++;
}
bb = uta->utiles[ix];
if (bb == 0)
bb = ART_UTA_BBOX_CONS(0, yf0, xf1, yf1);
else
bb = ART_UTA_BBOX_CONS(0,
MIN(ART_UTA_BBOX_Y0(bb), yf0),
MAX(ART_UTA_BBOX_X1(bb), xf1),
MAX(ART_UTA_BBOX_Y1(bb), yf1));
uta->utiles[ix] = bb;
}
else
{
/* Do a Bresenham-style traversal of the line */
double dx_dy;
double x, y;
double xn, yn;
/* normalize coordinates to uta origin */
x0 -= uta->x0 << ART_UTILE_SHIFT;
y0 -= uta->y0 << ART_UTILE_SHIFT;
x1 -= uta->x0 << ART_UTILE_SHIFT;
y1 -= uta->y0 << ART_UTILE_SHIFT;
if (dy < 0)
{
double tmp;
tmp = x0;
x0 = x1;
x1 = tmp;
tmp = y0;
y0 = y1;
y1 = tmp;
dx = -dx;
sx = -sx;
dy = -dy;
/* we leave sy alone, because it would always be 1,
and we need it for the rbuf stuff. */
}
xt0 = ((int)floor (x0) >> ART_UTILE_SHIFT);
xt1 = ((int)floor (x1) >> ART_UTILE_SHIFT);
/* now [xy]0 is above [xy]1 */
ix = yt0 * uta->width + xt0;
ix1 = yt1 * uta->width + xt1;
#ifdef VERBOSE
printf ("%% ix = %d,%d; ix1 = %d,%d\n", xt0, yt0, xt1, yt1);
#endif
dx_dy = dx / dy;
x = x0;
y = y0;
while (ix != ix1)
{
int dix;
/* figure out whether next crossing is horizontal or vertical */
#ifdef VERBOSE
printf ("%% %d,%d\n", xt0, yt0);
#endif
yn = (yt0 + 1) << ART_UTILE_SHIFT;
/* xn is the intercept with bottom edge of this tile. The
following expression is careful to result in exactly
x1 when yn = y1. */
xn = x1 + dx_dy * (yn - y1);
if (xt0 != (int)floor (xn) >> ART_UTILE_SHIFT)
{
/* horizontal crossing */
xt0 += sx;
dix = sx;
if (dx > 0)
{
xn = xt0 << ART_UTILE_SHIFT;
yn = y0 + (xn - x0) / dx_dy;
xf0 = (int)floor (x) & (ART_UTILE_SIZE - 1);
xf1 = ART_UTILE_SIZE;
}
else
{
xn = (xt0 + 1) << ART_UTILE_SHIFT;
yn = y0 + (xn - x0) / dx_dy;
xf0 = 0;
xmaxc = (int)ceil (x);
xf1 = xmaxc - ((xt0 + 1) << ART_UTILE_SHIFT);
}
ymaxf = (int)floor (yn);
ymaxc = (int)ceil (yn);
yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf;
}
else
{
/* vertical crossing */
dix = uta->width;
xf0 = (int)floor (MIN(x, xn)) & (ART_UTILE_SIZE - 1);
xmax = MAX(x, xn);
xmaxc = (int)ceil (xmax);
xf1 = xmaxc - (xt0 << ART_UTILE_SHIFT);
yf1 = ART_UTILE_SIZE;
if (rbuf != NULL)
rbuf[yt0 * rbuf_rowstride + xt0] += sy;
yt0++;
}
yf0 = (int)floor (y) & (ART_UTILE_SIZE - 1);
bb = uta->utiles[ix];
if (bb == 0)
bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1);
else
bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0),
MIN(ART_UTA_BBOX_Y0(bb), yf0),
MAX(ART_UTA_BBOX_X1(bb), xf1),
MAX(ART_UTA_BBOX_Y1(bb), yf1));
uta->utiles[ix] = bb;
x = xn;
y = yn;
ix += dix;
}
xmax = MAX(x, x1);
xmaxc = ceil (xmax);
ymaxc = ceil (y1);
xf0 = (int)floor (MIN(x1, x)) & (ART_UTILE_SIZE - 1);
yf0 = (int)floor (y) & (ART_UTILE_SIZE - 1);
xf1 = xmaxc - (xt0 << ART_UTILE_SHIFT);
yf1 = ymaxc - (yt0 << ART_UTILE_SHIFT);
bb = uta->utiles[ix];
if (bb == 0)
bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1);
else
bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0),
MIN(ART_UTA_BBOX_Y0(bb), yf0),
MAX(ART_UTA_BBOX_X1(bb), xf1),
MAX(ART_UTA_BBOX_Y1(bb), yf1));
uta->utiles[ix] = bb;
}
}
}
/**
* art_uta_from_vpath: Generate uta covering a vpath.
* @vec: The source vpath.
*
* Generates a uta covering @vec. The resulting uta is of course
* approximate, ie it may cover more pixels than covered by @vec.
*
* Return value: the new uta.
**/
ArtUta *
art_uta_from_vpath (const ArtVpath *vec)
{
ArtUta *uta;
ArtIRect bbox;
int *rbuf;
int i;
double x, y;
int sum;
int xt, yt;
ArtUtaBbox *utiles;
ArtUtaBbox bb;
int width;
int height;
int ix;
art_vpath_bbox_irect (vec, &bbox);
uta = art_uta_new_coords (bbox.x0, bbox.y0, bbox.x1, bbox.y1);
width = uta->width;
height = uta->height;
utiles = uta->utiles;
rbuf = art_new (int, width * height);
for (i = 0; i < width * height; i++)
rbuf[i] = 0;
x = 0;
y = 0;
for (i = 0; vec[i].code != ART_END; i++)
{
switch (vec[i].code)
{
case ART_MOVETO:
x = vec[i].x;
y = vec[i].y;
break;
case ART_LINETO:
art_uta_add_line (uta, vec[i].x, vec[i].y, x, y, rbuf, width);
x = vec[i].x;
y = vec[i].y;
break;
default:
/* this shouldn't happen */
art_free (rbuf);
art_free (uta);
return NULL;
}
}
/* now add in the filling from rbuf */
ix = 0;
for (yt = 0; yt < height; yt++)
{
sum = 0;
for (xt = 0; xt < width; xt++)
{
sum += rbuf[ix];
/* Nonzero winding rule - others are possible, but hardly
worth it. */
if (sum != 0)
{
bb = utiles[ix];
bb &= 0xffff0000;
bb |= (ART_UTILE_SIZE << 8) | ART_UTILE_SIZE;
utiles[ix] = bb;
if (xt != width - 1)
{
bb = utiles[ix + 1];
bb &= 0xffff00;
bb |= ART_UTILE_SIZE;
utiles[ix + 1] = bb;
}
if (yt != height - 1)
{
bb = utiles[ix + width];
bb &= 0xff0000ff;
bb |= ART_UTILE_SIZE << 8;
utiles[ix + width] = bb;
if (xt != width - 1)
{
utiles[ix + width + 1] &= 0xffff;
}
}
}
ix++;
}
}
art_free (rbuf);
return uta;
}
