pixman/pixman-image.c

   1 /*
   2  * Copyright © 2000 SuSE, Inc.
   3  * Copyright © 2007 Red Hat, Inc.
   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, and that the name of SuSE not be used in advertising or
  10  * publicity pertaining to distribution of the software without specific,
  11  * written prior permission.  SuSE makes no representations about the
  12  * suitability of this software for any purpose.  It is provided "as is"
  13  * without express or implied warranty.
  14  *
  15  * SuSE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL SuSE
  17  * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  18  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  19  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  20  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30 #include <assert.h>
  31
  32 #include "pixman-private.h"
  33 #include "pixman-combine32.h"
  34
  35 pixman_bool_t
  36 _pixman_init_gradient (gradient_t *                  gradient,
  37                        const pixman_gradient_stop_t *stops,
  38                        int                           n_stops)
  39 {
  40     return_val_if_fail (n_stops > 0, FALSE);
  41
  42     gradient->stops = pixman_malloc_ab (n_stops, sizeof (pixman_gradient_stop_t));
  43     if (!gradient->stops)
  44         return FALSE;
  45
  46     memcpy (gradient->stops, stops, n_stops * sizeof (pixman_gradient_stop_t));
  47
  48     gradient->n_stops = n_stops;
  49
  50     return TRUE;
  51 }
  52
  53 pixman_image_t *
  54 _pixman_image_allocate (void)
  55 {
  56     pixman_image_t *image = malloc (sizeof (pixman_image_t));
  57
  58     if (image)
  59     {
  60         image_common_t *common = &image->common;
  61
  62         pixman_region32_init (&common->clip_region);
  63
  64         common->alpha_count = 0;
  65         common->have_clip_region = FALSE;
  66         common->clip_sources = FALSE;
  67         common->transform = NULL;
  68         common->repeat = PIXMAN_REPEAT_NONE;
  69         common->filter = PIXMAN_FILTER_NEAREST;
  70         common->filter_params = NULL;
  71         common->n_filter_params = 0;
  72         common->alpha_map = NULL;
  73         common->component_alpha = FALSE;
  74         common->ref_count = 1;
  75         common->property_changed = NULL;
  76         common->client_clip = FALSE;
  77         common->destroy_func = NULL;
  78         common->destroy_data = NULL;
  79         common->dirty = TRUE;
  80     }
  81
  82     return image;
  83 }
  84
  85 static void
  86 image_property_changed (pixman_image_t *image)
  87 {
  88     image->common.dirty = TRUE;
  89 }
  90
  91 /* Ref Counting */
  92 PIXMAN_EXPORT pixman_image_t *
  93 pixman_image_ref (pixman_image_t *image)
  94 {
  95     image->common.ref_count++;
  96
  97     return image;
  98 }
  99
 100 /* returns TRUE when the image is freed */
 101 PIXMAN_EXPORT pixman_bool_t
 102 pixman_image_unref (pixman_image_t *image)
 103 {
 104     image_common_t *common = (image_common_t *)image;
 105
 106     common->ref_count--;
 107
 108     if (common->ref_count == 0)
 109     {
 110         if (image->common.destroy_func)
 111             image->common.destroy_func (image, image->common.destroy_data);
 112
 113         pixman_region32_fini (&common->clip_region);
 114
 115         if (common->transform)
 116             free (common->transform);
 117
 118         if (common->filter_params)
 119             free (common->filter_params);
 120
 121         if (common->alpha_map)
 122             pixman_image_unref ((pixman_image_t *)common->alpha_map);
 123
 124         if (image->type == LINEAR ||
 125             image->type == RADIAL ||
 126             image->type == CONICAL)
 127         {
 128             if (image->gradient.stops)
 129                 free (image->gradient.stops);
 130         }
 131
 132         if (image->type == BITS && image->bits.free_me)
 133             free (image->bits.free_me);
 134
 135         free (image);
 136
 137         return TRUE;
 138     }
 139
 140     return FALSE;
 141 }
 142
 143 PIXMAN_EXPORT void
 144 pixman_image_set_destroy_function (pixman_image_t *            image,
 145                                    pixman_image_destroy_func_t func,
 146                                    void *                      data)
 147 {
 148     image->common.destroy_func = func;
 149     image->common.destroy_data = data;
 150 }
 151
 152 PIXMAN_EXPORT void *
 153 pixman_image_get_destroy_data (pixman_image_t *image)
 154 {
 155   return image->common.destroy_data;
 156 }
 157
 158 void
 159 _pixman_image_reset_clip_region (pixman_image_t *image)
 160 {
 161     image->common.have_clip_region = FALSE;
 162 }
 163
 164 /* Executive Summary: This function is a no-op that only exists
 165  * for historical reasons.
 166  *
 167  * There used to be a bug in the X server where it would rely on
 168  * out-of-bounds accesses when it was asked to composite with a
 169  * window as the source. It would create a pixman image pointing
 170  * to some bogus position in memory, but then set a clip region
 171  * to the position where the actual bits were.
 172  *
 173  * Due to a bug in old versions of pixman, where it would not clip
 174  * against the image bounds when a clip region was set, this would
 175  * actually work. So when the pixman bug was fixed, a workaround was
 176  * added to allow certain out-of-bound accesses. This function disabled
 177  * those workarounds.
 178  *
 179  * Since 0.21.2, pixman doesn't do these workarounds anymore, so now
 180  * this function is a no-op.
 181  */
 182 PIXMAN_EXPORT void
 183 pixman_disable_out_of_bounds_workaround (void)
 184 {
 185 }
 186
 187 static void
 188 compute_image_info (pixman_image_t *image)
 189 {
 190     pixman_format_code_t code;
 191     uint32_t flags = 0;
 192
 193     /* Transform */
 194     if (!image->common.transform)
 195     {
 196         flags |= (FAST_PATH_ID_TRANSFORM        |
 197                   FAST_PATH_X_UNIT_POSITIVE     |
 198                   FAST_PATH_Y_UNIT_ZERO         |
 199                   FAST_PATH_AFFINE_TRANSFORM);
 200     }
 201     else
 202     {
 203         flags |= FAST_PATH_HAS_TRANSFORM;
 204
 205         if (image->common.transform->matrix[2][0] == 0                  &&
 206             image->common.transform->matrix[2][1] == 0                  &&
 207             image->common.transform->matrix[2][2] == pixman_fixed_1)
 208         {
 209             flags |= FAST_PATH_AFFINE_TRANSFORM;
 210
 211             if (image->common.transform->matrix[0][1] == 0 &&
 212                 image->common.transform->matrix[1][0] == 0)
 213             {
 214                 if (image->common.transform->matrix[0][0] == -pixman_fixed_1 &&
 215                     image->common.transform->matrix[1][1] == -pixman_fixed_1)
 216                 {
 217                     flags |= FAST_PATH_ROTATE_180_TRANSFORM;
 218                 }
 219                 flags |= FAST_PATH_SCALE_TRANSFORM;
 220             }
 221             else if (image->common.transform->matrix[0][0] == 0 &&
 222                      image->common.transform->matrix[1][1] == 0)
 223             {
 224                 pixman_fixed_t m01 = image->common.transform->matrix[0][1];
 225                 if (m01 == -image->common.transform->matrix[1][0])
 226                 {
 227                         if (m01 == -pixman_fixed_1)
 228                             flags |= FAST_PATH_ROTATE_90_TRANSFORM;
 229                         else if (m01 == pixman_fixed_1)
 230                             flags |= FAST_PATH_ROTATE_270_TRANSFORM;
 231                 }
 232             }
 233         }
 234
 235         if (image->common.transform->matrix[0][0] > 0)
 236             flags |= FAST_PATH_X_UNIT_POSITIVE;
 237
 238         if (image->common.transform->matrix[1][0] == 0)
 239             flags |= FAST_PATH_Y_UNIT_ZERO;
 240     }
 241
 242     /* Filter */
 243     switch (image->common.filter)
 244     {
 245     case PIXMAN_FILTER_NEAREST:
 246     case PIXMAN_FILTER_FAST:
 247         flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
 248         break;
 249
 250     case PIXMAN_FILTER_BILINEAR:
 251     case PIXMAN_FILTER_GOOD:
 252     case PIXMAN_FILTER_BEST:
 253         flags |= (FAST_PATH_BILINEAR_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
 254         break;
 255
 256     case PIXMAN_FILTER_CONVOLUTION:
 257         break;
 258
 259     default:
 260         flags |= FAST_PATH_NO_CONVOLUTION_FILTER;
 261         break;
 262     }
 263
 264     /* Repeat mode */
 265     switch (image->common.repeat)
 266     {
 267     case PIXMAN_REPEAT_NONE:
 268         flags |=
 269             FAST_PATH_NO_REFLECT_REPEAT         |
 270             FAST_PATH_NO_PAD_REPEAT             |
 271             FAST_PATH_NO_NORMAL_REPEAT;
 272         break;
 273
 274     case PIXMAN_REPEAT_REFLECT:
 275         flags |=
 276             FAST_PATH_NO_PAD_REPEAT             |
 277             FAST_PATH_NO_NONE_REPEAT            |
 278             FAST_PATH_NO_NORMAL_REPEAT;
 279         break;
 280
 281     case PIXMAN_REPEAT_PAD:
 282         flags |=
 283             FAST_PATH_NO_REFLECT_REPEAT         |
 284             FAST_PATH_NO_NONE_REPEAT            |
 285             FAST_PATH_NO_NORMAL_REPEAT;
 286         break;
 287
 288     default:
 289         flags |=
 290             FAST_PATH_NO_REFLECT_REPEAT         |
 291             FAST_PATH_NO_PAD_REPEAT             |
 292             FAST_PATH_NO_NONE_REPEAT;
 293         break;
 294     }
 295
 296     /* Component alpha */
 297     if (image->common.component_alpha)
 298         flags |= FAST_PATH_COMPONENT_ALPHA;
 299     else
 300         flags |= FAST_PATH_UNIFIED_ALPHA;
 301
 302     flags |= (FAST_PATH_NO_ACCESSORS | FAST_PATH_NARROW_FORMAT);
 303
 304     /* Type specific checks */
 305     switch (image->type)
 306     {
 307     case SOLID:
 308         code = PIXMAN_solid;
 309
 310         if (image->solid.color.alpha == 0xffff)
 311             flags |= FAST_PATH_IS_OPAQUE;
 312         break;
 313
 314     case BITS:
 315         if (image->bits.width == 1      &&
 316             image->bits.height == 1     &&
 317             image->common.repeat != PIXMAN_REPEAT_NONE)
 318         {
 319             code = PIXMAN_solid;
 320         }
 321         else
 322         {
 323             code = image->bits.format;
 324         }
 325
 326         if (!PIXMAN_FORMAT_A (image->bits.format)                               &&
 327             PIXMAN_FORMAT_TYPE (image->bits.format) != PIXMAN_TYPE_GRAY         &&
 328             PIXMAN_FORMAT_TYPE (image->bits.format) != PIXMAN_TYPE_COLOR)
 329         {
 330             flags |= FAST_PATH_SAMPLES_OPAQUE;
 331
 332             if (image->common.repeat != PIXMAN_REPEAT_NONE)
 333                 flags |= FAST_PATH_IS_OPAQUE;
 334         }
 335
 336         if (image->bits.read_func || image->bits.write_func)
 337             flags &= ~FAST_PATH_NO_ACCESSORS;
 338
 339         if (PIXMAN_FORMAT_IS_WIDE (image->bits.format))
 340             flags &= ~FAST_PATH_NARROW_FORMAT;
 341         break;
 342
 343     case RADIAL:
 344         code = PIXMAN_unknown;
 345
 346         /*
 347          * As explained in pixman-radial-gradient.c, every point of
 348          * the plane has a valid associated radius (and thus will be
 349          * colored) if and only if a is negative (i.e. one of the two
 350          * circles contains the other one).
 351          */
 352
 353         if (image->radial.a >= 0)
 354             break;
 355
 356         /* Fall through */
 357
 358     case CONICAL:
 359     case LINEAR:
 360         code = PIXMAN_unknown;
 361
 362         if (image->common.repeat != PIXMAN_REPEAT_NONE)
 363         {
 364             int i;
 365
 366             flags |= FAST_PATH_IS_OPAQUE;
 367             for (i = 0; i < image->gradient.n_stops; ++i)
 368             {
 369                 if (image->gradient.stops[i].color.alpha != 0xffff)
 370                 {
 371                     flags &= ~FAST_PATH_IS_OPAQUE;
 372                     break;
 373                 }
 374             }
 375         }
 376         break;
 377
 378     default:
 379         code = PIXMAN_unknown;
 380         break;
 381     }
 382
 383     /* Alpha map */
 384     if (!image->common.alpha_map)
 385     {
 386         flags |= FAST_PATH_NO_ALPHA_MAP;
 387     }
 388     else
 389     {
 390         if (PIXMAN_FORMAT_IS_WIDE (image->common.alpha_map->format))
 391             flags &= ~FAST_PATH_NARROW_FORMAT;
 392     }
 393
 394     /* Both alpha maps and convolution filters can introduce
 395      * non-opaqueness in otherwise opaque images. Also
 396      * an image with component alpha turned on is only opaque
 397      * if all channels are opaque, so we simply turn it off
 398      * unconditionally for those images.
 399      */
 400     if (image->common.alpha_map                                 ||
 401         image->common.filter == PIXMAN_FILTER_CONVOLUTION       ||
 402         image->common.component_alpha)
 403     {
 404         flags &= ~(FAST_PATH_IS_OPAQUE | FAST_PATH_SAMPLES_OPAQUE);
 405     }
 406
 407     image->common.flags = flags;
 408     image->common.extended_format_code = code;
 409 }
 410
 411 void
 412 _pixman_image_validate (pixman_image_t *image)
 413 {
 414     if (image->common.dirty)
 415     {
 416         compute_image_info (image);
 417
 418         /* It is important that property_changed is
 419          * called *after* compute_image_info() because
 420          * property_changed() can make use of the flags
 421          * to set up accessors etc.
 422          */
 423         if (image->common.property_changed)
 424             image->common.property_changed (image);
 425
 426         image->common.dirty = FALSE;
 427     }
 428
 429     if (image->common.alpha_map)
 430         _pixman_image_validate ((pixman_image_t *)image->common.alpha_map);
 431 }
 432
 433 PIXMAN_EXPORT pixman_bool_t
 434 pixman_image_set_clip_region32 (pixman_image_t *   image,
 435                                 pixman_region32_t *region)
 436 {
 437     image_common_t *common = (image_common_t *)image;
 438     pixman_bool_t result;
 439
 440     if (region)
 441     {
 442         if ((result = pixman_region32_copy (&common->clip_region, region)))
 443             image->common.have_clip_region = TRUE;
 444     }
 445     else
 446     {
 447         _pixman_image_reset_clip_region (image);
 448
 449         result = TRUE;
 450     }
 451
 452     image_property_changed (image);
 453
 454     return result;
 455 }
 456
 457 PIXMAN_EXPORT pixman_bool_t
 458 pixman_image_set_clip_region (pixman_image_t *   image,
 459                               pixman_region16_t *region)
 460 {
 461     image_common_t *common = (image_common_t *)image;
 462     pixman_bool_t result;
 463
 464     if (region)
 465     {
 466         if ((result = pixman_region32_copy_from_region16 (&common->clip_region, region)))
 467             image->common.have_clip_region = TRUE;
 468     }
 469     else
 470     {
 471         _pixman_image_reset_clip_region (image);
 472
 473         result = TRUE;
 474     }
 475
 476     image_property_changed (image);
 477
 478     return result;
 479 }
 480
 481 PIXMAN_EXPORT void
 482 pixman_image_set_has_client_clip (pixman_image_t *image,
 483                                   pixman_bool_t   client_clip)
 484 {
 485     image->common.client_clip = client_clip;
 486 }
 487
 488 PIXMAN_EXPORT pixman_bool_t
 489 pixman_image_set_transform (pixman_image_t *          image,
 490                             const pixman_transform_t *transform)
 491 {
 492     static const pixman_transform_t id =
 493     {
 494         { { pixman_fixed_1, 0, 0 },
 495           { 0, pixman_fixed_1, 0 },
 496           { 0, 0, pixman_fixed_1 } }
 497     };
 498
 499     image_common_t *common = (image_common_t *)image;
 500     pixman_bool_t result;
 501
 502     if (common->transform == transform)
 503         return TRUE;
 504
 505     if (!transform || memcmp (&id, transform, sizeof (pixman_transform_t)) == 0)
 506     {
 507         free (common->transform);
 508         common->transform = NULL;
 509         result = TRUE;
 510
 511         goto out;
 512     }
 513
 514     if (common->transform &&
 515         memcmp (common->transform, transform, sizeof (pixman_transform_t) == 0))
 516     {
 517         return TRUE;
 518     }
 519
 520     if (common->transform == NULL)
 521         common->transform = malloc (sizeof (pixman_transform_t));
 522
 523     if (common->transform == NULL)
 524     {
 525         result = FALSE;
 526
 527         goto out;
 528     }
 529
 530     memcpy (common->transform, transform, sizeof(pixman_transform_t));
 531
 532     result = TRUE;
 533
 534 out:
 535     image_property_changed (image);
 536
 537     return result;
 538 }
 539
 540 PIXMAN_EXPORT void
 541 pixman_image_set_repeat (pixman_image_t *image,
 542                          pixman_repeat_t repeat)
 543 {
 544     if (image->common.repeat == repeat)
 545         return;
 546
 547     image->common.repeat = repeat;
 548
 549     image_property_changed (image);
 550 }
 551
 552 PIXMAN_EXPORT pixman_bool_t
 553 pixman_image_set_filter (pixman_image_t *      image,
 554                          pixman_filter_t       filter,
 555                          const pixman_fixed_t *params,
 556                          int                   n_params)
 557 {
 558     image_common_t *common = (image_common_t *)image;
 559     pixman_fixed_t *new_params;
 560
 561     if (params == common->filter_params && filter == common->filter)
 562         return TRUE;
 563
 564     new_params = NULL;
 565     if (params)
 566     {
 567         new_params = pixman_malloc_ab (n_params, sizeof (pixman_fixed_t));
 568         if (!new_params)
 569             return FALSE;
 570
 571         memcpy (new_params,
 572                 params, n_params * sizeof (pixman_fixed_t));
 573     }
 574
 575     common->filter = filter;
 576
 577     if (common->filter_params)
 578         free (common->filter_params);
 579
 580     common->filter_params = new_params;
 581     common->n_filter_params = n_params;
 582
 583     image_property_changed (image);
 584     return TRUE;
 585 }
 586
 587 PIXMAN_EXPORT void
 588 pixman_image_set_source_clipping (pixman_image_t *image,
 589                                   pixman_bool_t   clip_sources)
 590 {
 591     if (image->common.clip_sources == clip_sources)
 592         return;
 593
 594     image->common.clip_sources = clip_sources;
 595
 596     image_property_changed (image);
 597 }
 598
 599 /* Unlike all the other property setters, this function does not
 600  * copy the content of indexed. Doing this copying is simply
 601  * way, way too expensive.
 602  */
 603 PIXMAN_EXPORT void
 604 pixman_image_set_indexed (pixman_image_t *        image,
 605                           const pixman_indexed_t *indexed)
 606 {
 607     bits_image_t *bits = (bits_image_t *)image;
 608
 609     if (bits->indexed == indexed)
 610         return;
 611
 612     bits->indexed = indexed;
 613
 614     image_property_changed (image);
 615 }
 616
 617 PIXMAN_EXPORT void
 618 pixman_image_set_alpha_map (pixman_image_t *image,
 619                             pixman_image_t *alpha_map,
 620                             int16_t         x,
 621                             int16_t         y)
 622 {
 623     image_common_t *common = (image_common_t *)image;
 624
 625     return_if_fail (!alpha_map || alpha_map->type == BITS);
 626
 627     if (alpha_map && common->alpha_count > 0)
 628     {
 629         /* If this image is being used as an alpha map itself,
 630          * then you can't give it an alpha map of its own.
 631          */
 632         return;
 633     }
 634
 635     if (alpha_map && alpha_map->common.alpha_map)
 636     {
 637         /* If the image has an alpha map of its own,
 638          * then it can't be used as an alpha map itself
 639          */
 640         return;
 641     }
 642
 643     if (common->alpha_map != (bits_image_t *)alpha_map)
 644     {
 645         if (common->alpha_map)
 646         {
 647             common->alpha_map->common.alpha_count--;
 648
 649             pixman_image_unref ((pixman_image_t *)common->alpha_map);
 650         }
 651
 652         if (alpha_map)
 653         {
 654             common->alpha_map = (bits_image_t *)pixman_image_ref (alpha_map);
 655
 656             common->alpha_map->common.alpha_count++;
 657         }
 658         else
 659         {
 660             common->alpha_map = NULL;
 661         }
 662     }
 663
 664     common->alpha_origin_x = x;
 665     common->alpha_origin_y = y;
 666
 667     image_property_changed (image);
 668 }
 669
 670 PIXMAN_EXPORT void
 671 pixman_image_set_component_alpha   (pixman_image_t *image,
 672                                     pixman_bool_t   component_alpha)
 673 {
 674     if (image->common.component_alpha == component_alpha)
 675         return;
 676
 677     image->common.component_alpha = component_alpha;
 678
 679     image_property_changed (image);
 680 }
 681
 682 PIXMAN_EXPORT pixman_bool_t
 683 pixman_image_get_component_alpha   (pixman_image_t       *image)
 684 {
 685     return image->common.component_alpha;
 686 }
 687
 688 PIXMAN_EXPORT void
 689 pixman_image_set_accessors (pixman_image_t *           image,
 690                             pixman_read_memory_func_t  read_func,
 691                             pixman_write_memory_func_t write_func)
 692 {
 693     return_if_fail (image != NULL);
 694
 695     if (image->type == BITS)
 696     {
 697         image->bits.read_func = read_func;
 698         image->bits.write_func = write_func;
 699
 700         image_property_changed (image);
 701     }
 702 }
 703
 704 PIXMAN_EXPORT uint32_t *
 705 pixman_image_get_data (pixman_image_t *image)
 706 {
 707     if (image->type == BITS)
 708         return image->bits.bits;
 709
 710     return NULL;
 711 }
 712
 713 PIXMAN_EXPORT int
 714 pixman_image_get_width (pixman_image_t *image)
 715 {
 716     if (image->type == BITS)
 717         return image->bits.width;
 718
 719     return 0;
 720 }
 721
 722 PIXMAN_EXPORT int
 723 pixman_image_get_height (pixman_image_t *image)
 724 {
 725     if (image->type == BITS)
 726         return image->bits.height;
 727
 728     return 0;
 729 }
 730
 731 PIXMAN_EXPORT int
 732 pixman_image_get_stride (pixman_image_t *image)
 733 {
 734     if (image->type == BITS)
 735         return image->bits.rowstride * (int) sizeof (uint32_t);
 736
 737     return 0;
 738 }
 739
 740 PIXMAN_EXPORT int
 741 pixman_image_get_depth (pixman_image_t *image)
 742 {
 743     if (image->type == BITS)
 744         return PIXMAN_FORMAT_DEPTH (image->bits.format);
 745
 746     return 0;
 747 }
 748
 749 PIXMAN_EXPORT pixman_format_code_t
 750 pixman_image_get_format (pixman_image_t *image)
 751 {
 752     if (image->type == BITS)
 753         return image->bits.format;
 754
 755     return 0;
 756 }
 757
 758 uint32_t
 759 _pixman_image_get_solid (pixman_implementation_t *imp,
 760                          pixman_image_t *         image,
 761                          pixman_format_code_t     format)
 762 {
 763     uint32_t result;
 764     pixman_iter_t iter;
 765
 766     _pixman_implementation_src_iter_init (
 767         imp, &iter, image, 0, 0, 1, 1,
 768         (uint8_t *)&result, ITER_NARROW);
 769
 770     result = *iter.get_scanline (&iter, NULL);
 771
 772     /* If necessary, convert RGB <--> BGR. */
 773     if (PIXMAN_FORMAT_TYPE (format) != PIXMAN_TYPE_ARGB)
 774     {
 775         result = (((result & 0xff000000) >>  0) |
 776                   ((result & 0x00ff0000) >> 16) |
 777                   ((result & 0x0000ff00) >>  0) |
 778                   ((result & 0x000000ff) << 16));
 779     }
 780
 781     return result;
 782 }