/mi/mifpolycon.c
C | 280 lines | 170 code | 26 blank | 84 comment | 29 complexity | e4cb49f7f2f16740f49295e5bbd68ca8 MD5 | raw file
- /***********************************************************
- Copyright 1987, 1998 The Open Group
- Permission to use, copy, modify, distribute, and sell this software and its
- documentation for any purpose is hereby granted without fee, provided that
- the above copyright notice appear in all copies and that both that
- copyright notice and this permission notice appear in supporting
- documentation.
- The above copyright notice and this permission notice shall be included in
- all copies or substantial portions of the Software.
- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
- AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- Except as contained in this notice, the name of The Open Group shall not be
- used in advertising or otherwise to promote the sale, use or other dealings
- in this Software without prior written authorization from The Open Group.
- Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.
- All Rights Reserved
- Permission to use, copy, modify, and distribute this software and its
- documentation for any purpose and without fee is hereby granted,
- provided that the above copyright notice appear in all copies and that
- both that copyright notice and this permission notice appear in
- supporting documentation, and that the name of Digital not be
- used in advertising or publicity pertaining to distribution of the
- software without specific, written prior permission.
- DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
- ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
- DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
- ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
- WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
- ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
- SOFTWARE.
- ******************************************************************/
- #ifdef HAVE_DIX_CONFIG_H
- #include <dix-config.h>
- #endif
- #include <math.h>
- #include <X11/X.h>
- #include "gcstruct.h"
- #include "windowstr.h"
- #include "pixmapstr.h"
- #include "mifpoly.h"
- static int GetFPolyYBounds(SppPointPtr pts, int n, double yFtrans,
- int *by, int *ty);
- /*
- * Written by Todd Newman; April. 1987.
- *
- * Fill a convex polygon. If the given polygon
- * is not convex, then the result is undefined.
- * The algorithm is to order the edges from smallest
- * y to largest by partitioning the array into a left
- * edge list and a right edge list. The algorithm used
- * to traverse each edge is digital differencing analyzer
- * line algorithm with y as the major axis. There's some funny linear
- * interpolation involved because of the subpixel postioning.
- */
- void
- miFillSppPoly(
- DrawablePtr dst,
- GCPtr pgc,
- int count, /* number of points */
- SppPointPtr ptsIn, /* the points */
- int xTrans, int yTrans, /* Translate each point by this */
- double xFtrans,
- double yFtrans /* translate before conversion
- by this amount. This provides
- a mechanism to match rounding
- errors with any shape that must
- meet the polygon exactly.
- */
- )
- {
- double xl = 0.0, xr = 0.0, /* x vals of left and right edges */
- 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,
- *width,
- *FirstWidth, /* output buffer */
- *Marked; /* set if this vertex has been used */
- int left, right, /* indices to first endpoints */
- nextleft,
- nextright; /* indices to second endpoints */
- DDXPointPtr ptsOut,
- FirstPoint; /* output buffer */
- if (pgc->miTranslate)
- {
- xTrans += dst->x;
- yTrans += dst->y;
- }
- imin = GetFPolyYBounds(ptsIn, count, yFtrans, &ymin, &ymax);
- y = ymax - ymin + 1;
- if ((count < 3) || (y <= 0))
- return;
- ptsOut = FirstPoint = malloc(sizeof(DDXPointRec) * y);
- width = FirstWidth = malloc(sizeof(int) * y);
- Marked = malloc(sizeof(int) * count);
- if(!ptsOut || !width || !Marked)
- {
- free(Marked);
- free(width);
- free(ptsOut);
- return;
- }
- 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 * max(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 * max(dy, 0);
- }
- }
- /*
- * generate scans to fill while we still have
- * a right edge as well as a left edge.
- */
- i = (min(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++) = cxr - cxl;
- (ptsOut++)->x = cxl + xTrans;
- }
- else
- {
- *(width++) = cxl - cxr;
- (ptsOut++)->x = cxr + xTrans;
- }
- y++;
- /* increment down the edges */
- xl += ml;
- xr += mr;
- j--;
- }
- } while (y <= ymax);
- /* Finally, fill the spans we've collected */
- (*pgc->ops->FillSpans)(dst, pgc,
- ptsOut-FirstPoint, FirstPoint, FirstWidth, 1);
- free(Marked);
- free(FirstWidth);
- free(FirstPoint);
- }
- /* Find the index of the point with the smallest y.also return the
- * smallest and largest y */
- static
- int
- GetFPolyYBounds(
- SppPointPtr pts,
- int n,
- double yFtrans,
- int *by,
- int *ty)
- {
- SppPointPtr ptMin;
- double ymin, ymax;
- SppPointPtr ptsStart = pts;
- 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;
- }