lib/art/art_rect_uta.c

   1 /* Libart_LGPL - library of basic graphic primitives
   2  * Copyright (C) 1998 Raph Levien
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #include "config.h"
  21 #include "art_rect_uta.h"
  22
  23 /* Functions to decompose a microtile array into a list of rectangles. */
  24
  25 /**
  26  * art_rect_list_from_uta: Decompose uta into list of rectangles.
  27  * @uta: The source uta.
  28  * @max_width: The maximum width of the resulting rectangles.
  29  * @max_height: The maximum height of the resulting rectangles.
  30  * @p_nrects: Where to store the number of returned rectangles.
  31  *
  32  * Allocates a new list of rectangles, sets *@p_nrects to the number
  33  * in the list. This list should be freed with art_free().
  34  *
  35  * Each rectangle bounded in size by (@max_width, @max_height).
  36  * However, these bounds must be at least the size of one tile.
  37  *
  38  * This routine provides a precise implementation, i.e. the rectangles
  39  * cover exactly the same area as the uta. It is thus appropriate in
  40  * cases where the overhead per rectangle is small compared with the
  41  * cost of filling in extra pixels.
  42  *
  43  * Return value: An array containing the resulting rectangles.
  44  **/
  45 ArtIRect *
  46 art_rect_list_from_uta (ArtUta *uta, int max_width, int max_height,
  47                         int *p_nrects)
  48 {
  49   ArtIRect *rects;
  50   int n_rects, n_rects_max;
  51   int x, y;
  52   int width, height;
  53   int ix;
  54   int left_ix;
  55   ArtUtaBbox *utiles;
  56   ArtUtaBbox bb;
  57   int x0, y0, x1, y1;
  58   int *glom;
  59   int glom_rect;
  60
  61   n_rects = 0;
  62   n_rects_max = 1;
  63   rects = art_new (ArtIRect, n_rects_max);
  64
  65   width = uta->width;
  66   height = uta->height;
  67   utiles = uta->utiles;
  68
  69   glom = art_new (int, width * height);
  70   for (ix = 0; ix < width * height; ix++)
  71     glom[ix] = -1;
  72
  73   ix = 0;
  74   for (y = 0; y < height; y++)
  75     for (x = 0; x < width; x++)
  76       {
  77         bb = utiles[ix];
  78         if (bb)
  79           {
  80             x0 = ((uta->x0 + x) << ART_UTILE_SHIFT) + ART_UTA_BBOX_X0(bb);
  81             y0 = ((uta->y0 + y) << ART_UTILE_SHIFT) + ART_UTA_BBOX_Y0(bb);
  82             y1 = ((uta->y0 + y) << ART_UTILE_SHIFT) + ART_UTA_BBOX_Y1(bb);
  83
  84             left_ix = ix;
  85             /* now try to extend to the right */
  86             while (x != width - 1 &&
  87                    ART_UTA_BBOX_X1(bb) == ART_UTILE_SIZE &&
  88                    (((bb & 0xffffff) ^ utiles[ix + 1]) & 0xffff00ff) == 0 &&
  89                    (((uta->x0 + x + 1) << ART_UTILE_SHIFT) +
  90                     ART_UTA_BBOX_X1(utiles[ix + 1]) -
  91                     x0) <= max_width)
  92               {
  93                 bb = utiles[ix + 1];
  94                 ix++;
  95                 x++;
  96               }
  97             x1 = ((uta->x0 + x) << ART_UTILE_SHIFT) + ART_UTA_BBOX_X1(bb);
  98
  99
 100             /* if rectangle nonempty */
 101             if ((x1 ^ x0) | (y1 ^ y0))
 102               {
 103                 /* try to glom onto an existing rectangle */
 104                 glom_rect = glom[left_ix];
 105                 if (glom_rect != -1 &&
 106                     x0 == rects[glom_rect].x0 &&
 107                     x1 == rects[glom_rect].x1 &&
 108                     y0 == rects[glom_rect].y1 &&
 109                     y1 - rects[glom_rect].y0 <= max_height)
 110                   {
 111                     rects[glom_rect].y1 = y1;
 112                   }
 113                 else
 114                   {
 115                     if (n_rects == n_rects_max)
 116                       art_expand (rects, ArtIRect, n_rects_max);
 117                     rects[n_rects].x0 = x0;
 118                     rects[n_rects].y0 = y0;
 119                     rects[n_rects].x1 = x1;
 120                     rects[n_rects].y1 = y1;
 121                     glom_rect = n_rects;
 122                     n_rects++;
 123                   }
 124                 if (y != height - 1)
 125                   glom[left_ix + width] = glom_rect;
 126               }
 127           }
 128         ix++;
 129       }
 130
 131   art_free (glom);
 132   *p_nrects = n_rects;
 133   return rects;
 134 }