xorg-server-1.4/mi/mipolycon.c

   1 /***********************************************************
   2
   3 Copyright 1987, 1998  The Open Group
   4
   5 Permission to use, copy, modify, distribute, and sell this software and its
   6 documentation for any purpose is hereby granted without fee, provided that
   7 the above copyright notice appear in all copies and that both that
   8 copyright notice and this permission notice appear in supporting
   9 documentation.
  10
  11 The above copyright notice and this permission notice shall be included in
  12 all copies or substantial portions of the Software.
  13
  14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  17 OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  18 AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  19 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  20
  21 Except as contained in this notice, the name of The Open Group shall not be
  22 used in advertising or otherwise to promote the sale, use or other dealings
  23 in this Software without prior written authorization from The Open Group.
  24
  25
  26 Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.
  27
  28                         All Rights Reserved
  29
  30 Permission to use, copy, modify, and distribute this software and its
  31 documentation for any purpose and without fee is hereby granted,
  32 provided that the above copyright notice appear in all copies and that
  33 both that copyright notice and this permission notice appear in
  34 supporting documentation, and that the name of Digital not be
  35 used in advertising or publicity pertaining to distribution of the
  36 software without specific, written prior permission.
  37
  38 DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
  39 ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
  40 DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
  41 ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  42 WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  43 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  44 SOFTWARE.
  45
  46 ******************************************************************/
  47
  48 #ifdef HAVE_DIX_CONFIG_H
  49 #include <dix-config.h>
  50 #endif
  51
  52 #include "gcstruct.h"
  53 #include "pixmap.h"
  54 #include "mi.h"
  55 #include "miscanfill.h"
  56
  57 static int getPolyYBounds(DDXPointPtr pts, int n, int *by, int *ty);
  58
  59 /*
  60  *     convexpoly.c
  61  *
  62  *     Written by Brian Kelleher; Dec. 1985.
  63  *
  64  *     Fill a convex polygon.  If the given polygon
  65  *     is not convex, then the result is undefined.
  66  *     The algorithm is to order the edges from smallest
  67  *     y to largest by partitioning the array into a left
  68  *     edge list and a right edge list.  The algorithm used
  69  *     to traverse each edge is an extension of Bresenham's
  70  *     line algorithm with y as the major axis.
  71  *     For a derivation of the algorithm, see the author of
  72  *     this code.
  73  */
  74 _X_EXPORT Bool
  75 miFillConvexPoly(dst, pgc, count, ptsIn)
  76     DrawablePtr dst;
  77     GCPtr       pgc;
  78     int         count;                /* number of points        */
  79     DDXPointPtr ptsIn;                /* the points              */
  80 {
  81     int xl = 0, xr = 0; /* x vals of left and right edges */
  82     int dl = 0, dr = 0; /* decision variables             */
  83     int ml = 0, m1l = 0;/* left edge slope and slope+1    */
  84     int mr = 0, m1r = 0;         /* right edge slope and slope+1   */
  85     int incr1l = 0, incr2l = 0;  /* left edge error increments     */
  86     int incr1r = 0, incr2r = 0;  /* right edge error increments    */
  87     int dy;                      /* delta y                        */
  88     int y;                       /* current scanline               */
  89     int left, right;             /* indices to first endpoints     */
  90     int i;                       /* loop counter                   */
  91     int nextleft, nextright;     /* indices to second endpoints    */
  92     DDXPointPtr ptsOut, FirstPoint; /* output buffer               */
  93     int *width, *FirstWidth;     /* output buffer                  */
  94     int imin;                    /* index of smallest vertex (in y) */
  95     int ymin;                    /* y-extents of polygon            */
  96     int ymax;
  97
  98     /*
  99      *  find leftx, bottomy, rightx, topy, and the index
 100      *  of bottomy. Also translate the points.
 101      */
 102     imin = getPolyYBounds(ptsIn, count, &ymin, &ymax);
 103
 104     dy = ymax - ymin + 1;
 105     if ((count < 3) || (dy < 0))
 106         return(TRUE);
 107     ptsOut = FirstPoint = (DDXPointPtr )ALLOCATE_LOCAL(sizeof(DDXPointRec)*dy);
 108     width = FirstWidth = (int *)ALLOCATE_LOCAL(sizeof(int) * dy);
 109     if(!FirstPoint || !FirstWidth)
 110     {
 111         if (FirstWidth) DEALLOCATE_LOCAL(FirstWidth);
 112         if (FirstPoint) DEALLOCATE_LOCAL(FirstPoint);
 113         return(FALSE);
 114     }
 115
 116     nextleft = nextright = imin;
 117     y = ptsIn[nextleft].y;
 118
 119     /*
 120      *  loop through all edges of the polygon
 121      */
 122     do {
 123         /*
 124          *  add a left edge if we need to
 125          */
 126         if (ptsIn[nextleft].y == y) {
 127             left = nextleft;
 128
 129             /*
 130              *  find the next edge, considering the end
 131              *  conditions of the array.
 132              */
 133             nextleft++;
 134             if (nextleft >= count)
 135                 nextleft = 0;
 136
 137             /*
 138              *  now compute all of the random information
 139              *  needed to run the iterative algorithm.
 140              */
 141             BRESINITPGON(ptsIn[nextleft].y-ptsIn[left].y,
 142                          ptsIn[left].x,ptsIn[nextleft].x,
 143                          xl, dl, ml, m1l, incr1l, incr2l);
 144         }
 145
 146         /*
 147          *  add a right edge if we need to
 148          */
 149         if (ptsIn[nextright].y == y) {
 150             right = nextright;
 151
 152             /*
 153              *  find the next edge, considering the end
 154              *  conditions of the array.
 155              */
 156             nextright--;
 157             if (nextright < 0)
 158                 nextright = count-1;
 159
 160             /*
 161              *  now compute all of the random information
 162              *  needed to run the iterative algorithm.
 163              */
 164             BRESINITPGON(ptsIn[nextright].y-ptsIn[right].y,
 165                          ptsIn[right].x,ptsIn[nextright].x,
 166                          xr, dr, mr, m1r, incr1r, incr2r);
 167         }
 168
 169         /*
 170          *  generate scans to fill while we still have
 171          *  a right edge as well as a left edge.
 172          */
 173         i = min(ptsIn[nextleft].y, ptsIn[nextright].y) - y;
 174         /* in case we're called with non-convex polygon */
 175         if(i < 0)
 176         {
 177             DEALLOCATE_LOCAL(FirstWidth);
 178             DEALLOCATE_LOCAL(FirstPoint);
 179             return(TRUE);
 180         }
 181         while (i-- > 0)
 182         {
 183             ptsOut->y = y;
 184
 185             /*
 186              *  reverse the edges if necessary
 187              */
 188             if (xl < xr)
 189             {
 190                 *(width++) = xr - xl;
 191                 (ptsOut++)->x = xl;
 192             }
 193             else
 194             {
 195                 *(width++) = xl - xr;
 196                 (ptsOut++)->x = xr;
 197             }
 198             y++;
 199
 200             /* increment down the edges */
 201             BRESINCRPGON(dl, xl, ml, m1l, incr1l, incr2l);
 202             BRESINCRPGON(dr, xr, mr, m1r, incr1r, incr2r);
 203         }
 204     }  while (y != ymax);
 205
 206     /*
 207      * Finally, fill the <remaining> spans
 208      */
 209     (*pgc->ops->FillSpans)(dst, pgc,
 210                       ptsOut-FirstPoint,FirstPoint,FirstWidth,
 211                       1);
 212     DEALLOCATE_LOCAL(FirstWidth);
 213     DEALLOCATE_LOCAL(FirstPoint);
 214     return(TRUE);
 215 }
 216
 217 \f
 218 /*
 219  *     Find the index of the point with the smallest y.
 220  */
 221 static int
 222 getPolyYBounds(DDXPointPtr pts, int n, int *by, int *ty)
 223 {
 224     DDXPointPtr ptMin;
 225     int ymin, ymax;
 226     DDXPointPtr ptsStart = pts;
 227
 228     ptMin = pts;
 229     ymin = ymax = (pts++)->y;
 230
 231     while (--n > 0) {
 232         if (pts->y < ymin)
 233         {
 234             ptMin = pts;
 235             ymin = pts->y;
 236         }
 237         if(pts->y > ymax)
 238             ymax = pts->y;
 239
 240         pts++;
 241     }
 242
 243     *by = ymin;
 244     *ty = ymax;
 245     return(ptMin-ptsStart);
 246 }