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/* This file is part of the GNU libxmi package.
Copyright (C) 1985, 1986, 1987, 1988, 1989, X Consortium. For an
associated permission notice, see the accompanying file README-X.
GNU enhancements Copyright (C) 1998, 1999, 2000, 2005, Free Software
Foundation, Inc.
The GNU libxmi 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 libxmi 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. */
#include "sys-defines.h"
#include "extern.h"
#include "xmi.h"
#include "mi_spans.h"
#include "mi_api.h"
#include "mi_fply.h"
/* forward references */
static int GetFPolyYBounds (const SppPoint *pts, int n, double yFtrans, int *by, int *ty);
/*
* Written by Todd Newman; April 1987.
* Hacked by Robert S. Maier, 1998-1999.
*
* Fill a convex polygon, with SPP (subpixel placement) of vertices. If
* the given polygon is not convex, then the result is undefined. All
* painting goes through the low-level MI_PAINT_SPANS() macro.
*
* In libxmi, this is used to draw polygonal line caps and line joins for
* poly-arcs. See mi_arc.c.
*
* The algorithm is to order the edges from smallest y to largest y, by
* partitioning the array into a left edge list and a right edge list. The
* algorithm used to traverse each edge is the digital differencing
* analyzer line algorithm, with y as the major axis. There's some funny
* linear interpolation involved because of the subpixel postioning. */
/* ARGS: count = # points, ptsIn = points,
xTrans,yTrans = translation for each point,
xFtrans,yFtrans = translation before conversion, which provides a
mechanism to match rounding errors with any
shape that meets the polygon exactly. */
void
miFillSppPoly (miPaintedSet *paintedSet, miPixel pixel, int count, const SppPoint *ptsIn, int xTrans, int yTrans, double xFtrans, double yFtrans)
{
double xl = 0.0, /* x vals of left and right edges */
xr = 0.0,
ml = 0.0, /* left edge slope */
mr = 0.0, /* right edge slope */
dy, /* delta y */
i; /* loop counter */
int y, /* current scanline */
j,
imin, /* index of vertex with smallest y */
ymin, /* y-extents of polygon */
ymax;
int left, right, /* indices to first endpoints */
nextleft,
nextright; /* indices to second endpoints */
int *Marked; /* set if this vertex has been used */
unsigned int *width,
*FirstWidth; /* output buffer */
miPoint *ptsOut,
*FirstPoint; /* output buffer */
imin = GetFPolyYBounds (ptsIn, count, yFtrans, &ymin, &ymax);
y = ymax - ymin + 1;
if ((count < 3) || (y <= 0))
return;
ptsOut = FirstPoint = (miPoint *)mi_xmalloc(sizeof(miPoint) * y);
width = FirstWidth = (unsigned int *)mi_xmalloc(sizeof(unsigned int) * y);
Marked = (int *) mi_xmalloc(sizeof(int) * count);
for (j = 0; j < count; j++)
Marked[j] = 0;
nextleft = nextright = imin;
Marked[imin] = -1;
y = ICEIL(ptsIn[nextleft].y + yFtrans);
/*
* loop through all edges of the polygon
*/
do
{
/* add a left edge if we need to */
if ((y > (ptsIn[nextleft].y + yFtrans) ||
ISEQUAL(y, ptsIn[nextleft].y + yFtrans))
&& Marked[nextleft] != 1)
{
Marked[nextleft]++;
left = nextleft++;
/* find the next edge, considering the end conditions */
if (nextleft >= count)
nextleft = 0;
/* now compute the starting point and slope */
dy = ptsIn[nextleft].y - ptsIn[left].y;
if (dy != 0.0)
{
ml = (ptsIn[nextleft].x - ptsIn[left].x) / dy;
dy = y - (ptsIn[left].y + yFtrans);
xl = (ptsIn[left].x + xFtrans) + ml * DMAX(dy, 0);
}
}
/* add a right edge if we need to */
if ((y > ptsIn[nextright].y + yFtrans)
||
(ISEQUAL(y, ptsIn[nextright].y + yFtrans)
&& Marked[nextright] != 1))
{
Marked[nextright]++;
right = nextright--;
/* find the next edge, considering the end conditions */
if (nextright < 0)
nextright = count - 1;
/* now compute the starting point and slope */
dy = ptsIn[nextright].y - ptsIn[right].y;
if (dy != 0.0)
{
mr = (ptsIn[nextright].x - ptsIn[right].x) / dy;
dy = y - (ptsIn[right].y + yFtrans);
xr = (ptsIn[right].x + xFtrans) + mr * DMAX(dy, 0);
}
}
/*
* generate scans to fill while we still have
* a right edge as well as a left edge.
*/
i = (DMIN(ptsIn[nextleft].y, ptsIn[nextright].y) + yFtrans) - y;
if (i < EPSILON)
{
if(Marked[nextleft] && Marked[nextright])
{
/* Arrgh, we're trapped! (no more points)
* Out, we've got to get out of here before this decadence saps
* our will completely! */
break;
}
continue;
}
else
{
j = (int) i;
if (!j)
j++;
}
while (j > 0)
{
int cxl, cxr;
ptsOut->y = (y) + yTrans;
cxl = ICEIL(xl);
cxr = ICEIL(xr);
/* reverse the edges if necessary */
if (xl < xr)
{
*(width++) = (unsigned int)(cxr - cxl);
(ptsOut++)->x = cxl + xTrans;
}
else
{
*(width++) = (unsigned int)(cxl - cxr);
(ptsOut++)->x = cxr + xTrans;
}
y++;
/* increment down the edges */
xl += ml;
xr += mr;
j--;
}
} while (y <= ymax);
free (Marked);
/* paint the spans (to miPaintedSet, or if NULL, to the canvas) */
MI_PAINT_SPANS(paintedSet, pixel, ptsOut - FirstPoint, FirstPoint, FirstWidth)
}
/* Find the index of the point with the smallest y. Also return the
smallest and largest y. */
static int
GetFPolyYBounds (const SppPoint *pts, int n, double yFtrans, int *by, int *ty)
{
const SppPoint *ptsStart = pts;
const SppPoint *ptMin;
double ymin, ymax;
ptMin = pts;
ymin = ymax = (pts++)->y;
while (--n > 0)
{
if (pts->y < ymin)
{
ptMin = pts;
ymin = pts->y;
}
if(pts->y > ymax)
ymax = pts->y;
pts++;
}
*by = ICEIL(ymin + yFtrans);
*ty = ICEIL(ymax + yFtrans - 1);
return (ptMin - ptsStart);
}
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