source/libs/pixman/pixman-src/pixman/pixman-edge.c

   1 /*
   2  * Copyright © 2004 Keith Packard
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that
   7  * copyright notice and this permission notice appear in supporting
   8  * documentation, and that the name of Keith Packard not be used in
   9  * advertising or publicity pertaining to distribution of the software without
  10  * specific, written prior permission.  Keith Packard makes no
  11  * representations about the suitability of this software for any purpose.  It
  12  * is provided "as is" without express or implied warranty.
  13  *
  14  * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  20  * PERFORMANCE OF THIS SOFTWARE.
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include <string.h>
  28
  29 #include "pixman-private.h"
  30 #include "pixman-accessor.h"
  31
  32 /*
  33  * Step across a small sample grid gap
  34  */
  35 #define RENDER_EDGE_STEP_SMALL(edge)                                    \
  36     {                                                                   \
  37         edge->x += edge->stepx_small;                                   \
  38         edge->e += edge->dx_small;                                      \
  39         if (edge->e > 0)                                                \
  40         {                                                               \
  41             edge->e -= edge->dy;                                        \
  42             edge->x += edge->signdx;                                    \
  43         }                                                               \
  44     }
  45
  46 /*
  47  * Step across a large sample grid gap
  48  */
  49 #define RENDER_EDGE_STEP_BIG(edge)                                      \
  50     {                                                                   \
  51         edge->x += edge->stepx_big;                                     \
  52         edge->e += edge->dx_big;                                        \
  53         if (edge->e > 0)                                                \
  54         {                                                               \
  55             edge->e -= edge->dy;                                        \
  56             edge->x += edge->signdx;                                    \
  57         }                                                               \
  58     }
  59
  60 #ifdef PIXMAN_FB_ACCESSORS
  61 #define PIXMAN_RASTERIZE_EDGES pixman_rasterize_edges_accessors
  62 #else
  63 #define PIXMAN_RASTERIZE_EDGES pixman_rasterize_edges_no_accessors
  64 #endif
  65
  66 /*
  67  * 4 bit alpha
  68  */
  69
  70 #define N_BITS  4
  71 #define RASTERIZE_EDGES rasterize_edges_4
  72
  73 #ifndef WORDS_BIGENDIAN
  74 #define SHIFT_4(o)      ((o) << 2)
  75 #else
  76 #define SHIFT_4(o)      ((1 - (o)) << 2)
  77 #endif
  78
  79 #define GET_4(x, o)      (((x) >> SHIFT_4 (o)) & 0xf)
  80 #define PUT_4(x, o, v)                                                  \
  81     (((x) & ~(0xf << SHIFT_4 (o))) | (((v) & 0xf) << SHIFT_4 (o)))
  82
  83 #define DEFINE_ALPHA(line, x)                                           \
  84     uint8_t   *__ap = (uint8_t *) line + ((x) >> 1);                    \
  85     int __ao = (x) & 1
  86
  87 #define STEP_ALPHA      ((__ap += __ao), (__ao ^= 1))
  88
  89 #define ADD_ALPHA(a)                                                    \
  90     {                                                                   \
  91         uint8_t __o = READ (image, __ap);                               \
  92         uint8_t __a = (a) + GET_4 (__o, __ao);                          \
  93         WRITE (image, __ap, PUT_4 (__o, __ao, __a | (0 - ((__a) >> 4)))); \
  94     }
  95
  96 #include "pixman-edge-imp.h"
  97
  98 #undef ADD_ALPHA
  99 #undef STEP_ALPHA
 100 #undef DEFINE_ALPHA
 101 #undef RASTERIZE_EDGES
 102 #undef N_BITS
 103
 104
 105 /*
 106  * 1 bit alpha
 107  */
 108
 109 #define N_BITS 1
 110 #define RASTERIZE_EDGES rasterize_edges_1
 111
 112 #include "pixman-edge-imp.h"
 113
 114 #undef RASTERIZE_EDGES
 115 #undef N_BITS
 116
 117 /*
 118  * 8 bit alpha
 119  */
 120
 121 static force_inline uint8_t
 122 clip255 (int x)
 123 {
 124     if (x > 255)
 125         return 255;
 126
 127     return x;
 128 }
 129
 130 #define ADD_SATURATE_8(buf, val, length)                                \
 131     do                                                                  \
 132     {                                                                   \
 133         int i__ = (length);                                             \
 134         uint8_t *buf__ = (buf);                                         \
 135         int val__ = (val);                                              \
 136                                                                         \
 137         while (i__--)                                                   \
 138         {                                                               \
 139             WRITE (image, (buf__), clip255 (READ (image, (buf__)) + (val__))); \
 140             (buf__)++;                                                  \
 141         }                                                               \
 142     } while (0)
 143
 144 /*
 145  * We want to detect the case where we add the same value to a long
 146  * span of pixels.  The triangles on the end are filled in while we
 147  * count how many sub-pixel scanlines contribute to the middle section.
 148  *
 149  *                 +--------------------------+
 150  *  fill_height =|   \                      /
 151  *                     +------------------+
 152  *                      |================|
 153  *                   fill_start       fill_end
 154  */
 155 static void
 156 rasterize_edges_8 (pixman_image_t *image,
 157                    pixman_edge_t * l,
 158                    pixman_edge_t * r,
 159                    pixman_fixed_t  t,
 160                    pixman_fixed_t  b)
 161 {
 162     pixman_fixed_t y = t;
 163     uint32_t  *line;
 164     int fill_start = -1, fill_end = -1;
 165     int fill_size = 0;
 166     uint32_t *buf = (image)->bits.bits;
 167     int stride = (image)->bits.rowstride;
 168     int width = (image)->bits.width;
 169
 170     line = buf + pixman_fixed_to_int (y) * stride;
 171
 172     for (;;)
 173     {
 174         uint8_t *ap = (uint8_t *) line;
 175         pixman_fixed_t lx, rx;
 176         int lxi, rxi;
 177
 178         /* clip X */
 179         lx = l->x;
 180         if (lx < 0)
 181             lx = 0;
 182
 183         rx = r->x;
 184
 185         if (pixman_fixed_to_int (rx) >= width)
 186         {
 187             /* Use the last pixel of the scanline, covered 100%.
 188              * We can't use the first pixel following the scanline,
 189              * because accessing it could result in a buffer overrun.
 190              */
 191             rx = pixman_int_to_fixed (width) - 1;
 192         }
 193
 194         /* Skip empty (or backwards) sections */
 195         if (rx > lx)
 196         {
 197             int lxs, rxs;
 198
 199             /* Find pixel bounds for span. */
 200             lxi = pixman_fixed_to_int (lx);
 201             rxi = pixman_fixed_to_int (rx);
 202
 203             /* Sample coverage for edge pixels */
 204             lxs = RENDER_SAMPLES_X (lx, 8);
 205             rxs = RENDER_SAMPLES_X (rx, 8);
 206
 207             /* Add coverage across row */
 208             if (lxi == rxi)
 209             {
 210                 WRITE (image, ap + lxi,
 211                        clip255 (READ (image, ap + lxi) + rxs - lxs));
 212             }
 213             else
 214             {
 215                 WRITE (image, ap + lxi,
 216                        clip255 (READ (image, ap + lxi) + N_X_FRAC (8) - lxs));
 217
 218                 /* Move forward so that lxi/rxi is the pixel span */
 219                 lxi++;
 220
 221                 /* Don't bother trying to optimize the fill unless
 222                  * the span is longer than 4 pixels. */
 223                 if (rxi - lxi > 4)
 224                 {
 225                     if (fill_start < 0)
 226                     {
 227                         fill_start = lxi;
 228                         fill_end = rxi;
 229                         fill_size++;
 230                     }
 231                     else
 232                     {
 233                         if (lxi >= fill_end || rxi < fill_start)
 234                         {
 235                             /* We're beyond what we saved, just fill it */
 236                             ADD_SATURATE_8 (ap + fill_start,
 237                                             fill_size * N_X_FRAC (8),
 238                                             fill_end - fill_start);
 239                             fill_start = lxi;
 240                             fill_end = rxi;
 241                             fill_size = 1;
 242                         }
 243                         else
 244                         {
 245                             /* Update fill_start */
 246                             if (lxi > fill_start)
 247                             {
 248                                 ADD_SATURATE_8 (ap + fill_start,
 249                                                 fill_size * N_X_FRAC (8),
 250                                                 lxi - fill_start);
 251                                 fill_start = lxi;
 252                             }
 253                             else if (lxi < fill_start)
 254                             {
 255                                 ADD_SATURATE_8 (ap + lxi, N_X_FRAC (8),
 256                                                 fill_start - lxi);
 257                             }
 258
 259                             /* Update fill_end */
 260                             if (rxi < fill_end)
 261                             {
 262                                 ADD_SATURATE_8 (ap + rxi,
 263                                                 fill_size * N_X_FRAC (8),
 264                                                 fill_end - rxi);
 265                                 fill_end = rxi;
 266                             }
 267                             else if (fill_end < rxi)
 268                             {
 269                                 ADD_SATURATE_8 (ap + fill_end,
 270                                                 N_X_FRAC (8),
 271                                                 rxi - fill_end);
 272                             }
 273                             fill_size++;
 274                         }
 275                     }
 276                 }
 277                 else
 278                 {
 279                     ADD_SATURATE_8 (ap + lxi, N_X_FRAC (8), rxi - lxi);
 280                 }
 281
 282                 WRITE (image, ap + rxi, clip255 (READ (image, ap + rxi) + rxs));
 283             }
 284         }
 285
 286         if (y == b)
 287         {
 288             /* We're done, make sure we clean up any remaining fill. */
 289             if (fill_start != fill_end)
 290             {
 291                 if (fill_size == N_Y_FRAC (8))
 292                 {
 293                     MEMSET_WRAPPED (image, ap + fill_start,
 294                                     0xff, fill_end - fill_start);
 295                 }
 296                 else
 297                 {
 298                     ADD_SATURATE_8 (ap + fill_start, fill_size * N_X_FRAC (8),
 299                                     fill_end - fill_start);
 300                 }
 301             }
 302             break;
 303         }
 304
 305         if (pixman_fixed_frac (y) != Y_FRAC_LAST (8))
 306         {
 307             RENDER_EDGE_STEP_SMALL (l);
 308             RENDER_EDGE_STEP_SMALL (r);
 309             y += STEP_Y_SMALL (8);
 310         }
 311         else
 312         {
 313             RENDER_EDGE_STEP_BIG (l);
 314             RENDER_EDGE_STEP_BIG (r);
 315             y += STEP_Y_BIG (8);
 316             if (fill_start != fill_end)
 317             {
 318                 if (fill_size == N_Y_FRAC (8))
 319                 {
 320                     MEMSET_WRAPPED (image, ap + fill_start,
 321                                     0xff, fill_end - fill_start);
 322                 }
 323                 else
 324                 {
 325                     ADD_SATURATE_8 (ap + fill_start, fill_size * N_X_FRAC (8),
 326                                     fill_end - fill_start);
 327                 }
 328
 329                 fill_start = fill_end = -1;
 330                 fill_size = 0;
 331             }
 332
 333             line += stride;
 334         }
 335     }
 336 }
 337
 338 #ifndef PIXMAN_FB_ACCESSORS
 339 static
 340 #endif
 341 void
 342 PIXMAN_RASTERIZE_EDGES (pixman_image_t *image,
 343                         pixman_edge_t * l,
 344                         pixman_edge_t * r,
 345                         pixman_fixed_t  t,
 346                         pixman_fixed_t  b)
 347 {
 348     switch (PIXMAN_FORMAT_BPP (image->bits.format))
 349     {
 350     case 1:
 351         rasterize_edges_1 (image, l, r, t, b);
 352         break;
 353
 354     case 4:
 355         rasterize_edges_4 (image, l, r, t, b);
 356         break;
 357
 358     case 8:
 359         rasterize_edges_8 (image, l, r, t, b);
 360         break;
 361
 362     default:
 363         break;
 364     }
 365 }
 366
 367 #ifndef PIXMAN_FB_ACCESSORS
 368
 369 PIXMAN_EXPORT void
 370 pixman_rasterize_edges (pixman_image_t *image,
 371                         pixman_edge_t * l,
 372                         pixman_edge_t * r,
 373                         pixman_fixed_t  t,
 374                         pixman_fixed_t  b)
 375 {
 376     return_if_fail (image->type == BITS);
 377     return_if_fail (PIXMAN_FORMAT_TYPE (image->bits.format) == PIXMAN_TYPE_A);
 378
 379     if (image->bits.read_func || image->bits.write_func)
 380         pixman_rasterize_edges_accessors (image, l, r, t, b);
 381     else
 382         pixman_rasterize_edges_no_accessors (image, l, r, t, b);
 383 }
 384
 385 #endif