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