src/mesa/main/texgetimage.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.5
   4  *
   5  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
   6  * Copyright (c) 2009 VMware, Inc.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26
  27 /**
  28  * Code for glGetTexImage() and glGetCompressedTexImage().
  29  */
  30
  31
  32 #include "glheader.h"
  33 #include "bufferobj.h"
  34 #include "context.h"
  35 #include "image.h"
  36 #include "texcompress.h"
  37 #include "texformat.h"
  38 #include "texgetimage.h"
  39 #include "teximage.h"
  40 #include "texstate.h"
  41
  42
  43
  44 #if FEATURE_EXT_texture_sRGB
  45
  46 /**
  47  * Test if given texture image is an sRGB format.
  48  */
  49 static GLboolean
  50 is_srgb_teximage(const struct gl_texture_image *texImage)
  51 {
  52    switch (texImage->TexFormat) {
  53    case MESA_FORMAT_SRGB8:
  54    case MESA_FORMAT_SRGBA8:
  55    case MESA_FORMAT_SARGB8:
  56    case MESA_FORMAT_SL8:
  57    case MESA_FORMAT_SLA8:
  58    case MESA_FORMAT_SRGB_DXT1:
  59    case MESA_FORMAT_SRGBA_DXT1:
  60    case MESA_FORMAT_SRGBA_DXT3:
  61    case MESA_FORMAT_SRGBA_DXT5:
  62       return GL_TRUE;
  63    default:
  64       return GL_FALSE;
  65    }
  66 }
  67
  68
  69 /**
  70  * Convert a float value from linear space to a
  71  * non-linear sRGB value in [0, 255].
  72  * Not terribly efficient.
  73  */
  74 static INLINE GLfloat
  75 linear_to_nonlinear(GLfloat cl)
  76 {
  77    /* can't have values outside [0, 1] */
  78    GLfloat cs;
  79    if (cl < 0.0031308f) {
  80       cs = 12.92f * cl;
  81    }
  82    else {
  83       cs = (GLfloat)(1.055 * _mesa_pow(cl, 0.41666) - 0.055);
  84    }
  85    return cs;
  86 }
  87
  88 #endif /* FEATURE_EXT_texture_sRGB */
  89
  90
  91 /**
  92  * Can the given type represent negative values?
  93  */
  94 static INLINE GLboolean
  95 type_with_negative_values(GLenum type)
  96 {
  97    switch (type) {
  98    case GL_BYTE:
  99    case GL_SHORT:
 100    case GL_INT:
 101    case GL_FLOAT:
 102    case GL_HALF_FLOAT_ARB:
 103       return GL_TRUE;
 104    default:
 105       return GL_FALSE;
 106    }
 107 }
 108
 109
 110 /**
 111  * This is the software fallback for Driver.GetTexImage().
 112  * All error checking will have been done before this routine is called.
 113  */
 114 void
 115 _mesa_get_teximage(GLcontext *ctx, GLenum target, GLint level,
 116                    GLenum format, GLenum type, GLvoid *pixels,
 117                    struct gl_texture_object *texObj,
 118                    struct gl_texture_image *texImage)
 119 {
 120    const GLuint dimensions = (target == GL_TEXTURE_3D) ? 3 : 2;
 121
 122    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
 123       /* Packing texture image into a PBO.
 124        * Map the (potentially) VRAM-based buffer into our process space so
 125        * we can write into it with the code below.
 126        * A hardware driver might use a sophisticated blit to move the
 127        * texture data to the PBO if the PBO is in VRAM along with the texture.
 128        */
 129       GLubyte *buf = (GLubyte *)
 130          ctx->Driver.MapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 131                                GL_WRITE_ONLY_ARB, ctx->Pack.BufferObj);
 132       if (!buf) {
 133          /* buffer is already mapped - that's an error */
 134          _mesa_error(ctx, GL_INVALID_OPERATION,"glGetTexImage(PBO is mapped)");
 135          return;
 136       }
 137       /* <pixels> was an offset into the PBO.
 138        * Now make it a real, client-side pointer inside the mapped region.
 139        */
 140       pixels = ADD_POINTERS(buf, pixels);
 141    }
 142    else if (!pixels) {
 143       /* not an error */
 144       return;
 145    }
 146
 147    {
 148       const GLint width = texImage->Width;
 149       const GLint height = texImage->Height;
 150       const GLint depth = texImage->Depth;
 151       GLint img, row;
 152       for (img = 0; img < depth; img++) {
 153          for (row = 0; row < height; row++) {
 154             /* compute destination address in client memory */
 155             GLvoid *dest = _mesa_image_address( dimensions, &ctx->Pack, pixels,
 156                                                 width, height, format, type,
 157                                                 img, row, 0);
 158             assert(dest);
 159
 160             if (format == GL_COLOR_INDEX) {
 161                GLuint indexRow[MAX_WIDTH];
 162                GLint col;
 163                GLuint indexBits = _mesa_get_format_bits(texImage->TexFormat, GL_TEXTURE_INDEX_SIZE_EXT);
 164                /* Can't use FetchTexel here because that returns RGBA */
 165                if (indexBits == 8) {
 166                   const GLubyte *src = (const GLubyte *) texImage->Data;
 167                   src += width * (img * texImage->Height + row);
 168                   for (col = 0; col < width; col++) {
 169                      indexRow[col] = src[col];
 170                   }
 171                }
 172                else if (indexBits == 16) {
 173                   const GLushort *src = (const GLushort *) texImage->Data;
 174                   src += width * (img * texImage->Height + row);
 175                   for (col = 0; col < width; col++) {
 176                      indexRow[col] = src[col];
 177                   }
 178                }
 179                else {
 180                   _mesa_problem(ctx,
 181                                 "Color index problem in _mesa_GetTexImage");
 182                }
 183                _mesa_pack_index_span(ctx, width, type, dest,
 184                                      indexRow, &ctx->Pack,
 185                                      0 /* no image transfer */);
 186             }
 187             else if (format == GL_DEPTH_COMPONENT) {
 188                GLfloat depthRow[MAX_WIDTH];
 189                GLint col;
 190                for (col = 0; col < width; col++) {
 191                   (*texImage->FetchTexelf)(texImage, col, row, img,
 192                                            depthRow + col);
 193                }
 194                _mesa_pack_depth_span(ctx, width, dest, type,
 195                                      depthRow, &ctx->Pack);
 196             }
 197             else if (format == GL_DEPTH_STENCIL_EXT) {
 198                /* XXX Note: we're bypassing texImage->FetchTexel()! */
 199                const GLuint *src = (const GLuint *) texImage->Data;
 200                src += width * row + width * height * img;
 201                _mesa_memcpy(dest, src, width * sizeof(GLuint));
 202                if (ctx->Pack.SwapBytes) {
 203                   _mesa_swap4((GLuint *) dest, width);
 204                }
 205             }
 206             else if (format == GL_YCBCR_MESA) {
 207                /* No pixel transfer */
 208                const GLint rowstride = texImage->RowStride;
 209                MEMCPY(dest,
 210                       (const GLushort *) texImage->Data + row * rowstride,
 211                       width * sizeof(GLushort));
 212                /* check for byte swapping */
 213                if ((texImage->TexFormat == MESA_FORMAT_YCBCR
 214                     && type == GL_UNSIGNED_SHORT_8_8_REV_MESA) ||
 215                    (texImage->TexFormat == MESA_FORMAT_YCBCR_REV
 216                     && type == GL_UNSIGNED_SHORT_8_8_MESA)) {
 217                   if (!ctx->Pack.SwapBytes)
 218                      _mesa_swap2((GLushort *) dest, width);
 219                }
 220                else if (ctx->Pack.SwapBytes) {
 221                   _mesa_swap2((GLushort *) dest, width);
 222                }
 223             }
 224 #if FEATURE_EXT_texture_sRGB
 225             else if (is_srgb_teximage(texImage)) {
 226                /* special case this since need to backconvert values */
 227                /* convert row to RGBA format */
 228                GLfloat rgba[MAX_WIDTH][4];
 229                GLint col;
 230                GLbitfield transferOps = 0x0;
 231
 232                for (col = 0; col < width; col++) {
 233                   (*texImage->FetchTexelf)(texImage, col, row, img, rgba[col]);
 234                   if (texImage->_BaseFormat == GL_LUMINANCE) {
 235                      rgba[col][RCOMP] = linear_to_nonlinear(rgba[col][RCOMP]);
 236                      rgba[col][GCOMP] = 0.0;
 237                      rgba[col][BCOMP] = 0.0;
 238                   }
 239                   else if (texImage->_BaseFormat == GL_LUMINANCE_ALPHA) {
 240                      rgba[col][RCOMP] = linear_to_nonlinear(rgba[col][RCOMP]);
 241                      rgba[col][GCOMP] = 0.0;
 242                      rgba[col][BCOMP] = 0.0;
 243                   }
 244                   else if (texImage->_BaseFormat == GL_RGB ||
 245                      texImage->_BaseFormat == GL_RGBA) {
 246                      rgba[col][RCOMP] = linear_to_nonlinear(rgba[col][RCOMP]);
 247                      rgba[col][GCOMP] = linear_to_nonlinear(rgba[col][GCOMP]);
 248                      rgba[col][BCOMP] = linear_to_nonlinear(rgba[col][BCOMP]);
 249                   }
 250                }
 251                _mesa_pack_rgba_span_float(ctx, width, (GLfloat (*)[4]) rgba,
 252                                           format, type, dest,
 253                                           &ctx->Pack, transferOps);
 254             }
 255 #endif /* FEATURE_EXT_texture_sRGB */
 256             else {
 257                /* general case:  convert row to RGBA format */
 258                GLfloat rgba[MAX_WIDTH][4];
 259                GLint col;
 260                GLbitfield transferOps = 0x0;
 261                GLenum dataType =
 262                   _mesa_get_format_datatype(texImage->TexFormat);
 263
 264                /* clamp does not apply to GetTexImage (final conversion)?
 265                 * Looks like we need clamp though when going from format
 266                 * containing negative values to unsigned format.
 267                 */
 268                if (format == GL_LUMINANCE || format == GL_LUMINANCE_ALPHA)
 269                   transferOps |= IMAGE_CLAMP_BIT;
 270                else if (!type_with_negative_values(type) &&
 271                         (dataType == GL_FLOAT ||
 272                          dataType == GL_SIGNED_NORMALIZED))
 273                   transferOps |= IMAGE_CLAMP_BIT;
 274
 275                for (col = 0; col < width; col++) {
 276                   (*texImage->FetchTexelf)(texImage, col, row, img, rgba[col]);
 277                   if (texImage->_BaseFormat == GL_ALPHA) {
 278                      rgba[col][RCOMP] = 0.0;
 279                      rgba[col][GCOMP] = 0.0;
 280                      rgba[col][BCOMP] = 0.0;
 281                   }
 282                   else if (texImage->_BaseFormat == GL_LUMINANCE) {
 283                      rgba[col][GCOMP] = 0.0;
 284                      rgba[col][BCOMP] = 0.0;
 285                      rgba[col][ACOMP] = 1.0;
 286                   }
 287                   else if (texImage->_BaseFormat == GL_LUMINANCE_ALPHA) {
 288                      rgba[col][GCOMP] = 0.0;
 289                      rgba[col][BCOMP] = 0.0;
 290                   }
 291                   else if (texImage->_BaseFormat == GL_INTENSITY) {
 292                      rgba[col][GCOMP] = 0.0;
 293                      rgba[col][BCOMP] = 0.0;
 294                      rgba[col][ACOMP] = 1.0;
 295                   }
 296                }
 297                _mesa_pack_rgba_span_float(ctx, width, (GLfloat (*)[4]) rgba,
 298                                           format, type, dest,
 299                                           &ctx->Pack, transferOps);
 300             } /* format */
 301          } /* row */
 302       } /* img */
 303    }
 304
 305    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
 306       ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 307                               ctx->Pack.BufferObj);
 308    }
 309 }
 310
 311
 312
 313 /**
 314  * This is the software fallback for Driver.GetCompressedTexImage().
 315  * All error checking will have been done before this routine is called.
 316  */
 317 void
 318 _mesa_get_compressed_teximage(GLcontext *ctx, GLenum target, GLint level,
 319                               GLvoid *img,
 320                               struct gl_texture_object *texObj,
 321                               struct gl_texture_image *texImage)
 322 {
 323    GLuint size;
 324
 325    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
 326       /* pack texture image into a PBO */
 327       GLubyte *buf;
 328       if ((const GLubyte *) img + texImage->CompressedSize >
 329           (const GLubyte *) ctx->Pack.BufferObj->Size) {
 330          _mesa_error(ctx, GL_INVALID_OPERATION,
 331                      "glGetCompressedTexImage(invalid PBO access)");
 332          return;
 333       }
 334       buf = (GLubyte *) ctx->Driver.MapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 335                                               GL_WRITE_ONLY_ARB,
 336                                               ctx->Pack.BufferObj);
 337       if (!buf) {
 338          /* buffer is already mapped - that's an error */
 339          _mesa_error(ctx, GL_INVALID_OPERATION,
 340                      "glGetCompressedTexImage(PBO is mapped)");
 341          return;
 342       }
 343       img = ADD_POINTERS(buf, img);
 344    }
 345    else if (!img) {
 346       /* not an error */
 347       return;
 348    }
 349
 350    /* don't use texImage->CompressedSize since that may be padded out */
 351    size = _mesa_compressed_texture_size(ctx, texImage->Width, texImage->Height,
 352                                         texImage->Depth,
 353                                         texImage->TexFormat);
 354
 355    /* just memcpy, no pixelstore or pixel transfer */
 356    _mesa_memcpy(img, texImage->Data, size);
 357
 358    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
 359       ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 360                               ctx->Pack.BufferObj);
 361    }
 362 }
 363
 364
 365
 366 /**
 367  * Do error checking for a glGetTexImage() call.
 368  * \return GL_TRUE if any error, GL_FALSE if no errors.
 369  */
 370 static GLboolean
 371 getteximage_error_check(GLcontext *ctx, GLenum target, GLint level,
 372                         GLenum format, GLenum type, GLvoid *pixels )
 373 {
 374    const struct gl_texture_unit *texUnit;
 375    struct gl_texture_object *texObj;
 376    struct gl_texture_image *texImage;
 377    const GLuint maxLevels = _mesa_max_texture_levels(ctx, target);
 378    GLenum baseFormat;
 379
 380    if (maxLevels == 0) {
 381       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(target=0x%x)", target);
 382       return GL_TRUE;
 383    }
 384
 385    if (level < 0 || level >= maxLevels) {
 386       _mesa_error( ctx, GL_INVALID_VALUE, "glGetTexImage(level)" );
 387       return GL_TRUE;
 388    }
 389
 390    if (_mesa_sizeof_packed_type(type) <= 0) {
 391       _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexImage(type)" );
 392       return GL_TRUE;
 393    }
 394
 395    if (_mesa_components_in_format(format) <= 0 ||
 396        format == GL_STENCIL_INDEX) {
 397       _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexImage(format)" );
 398       return GL_TRUE;
 399    }
 400
 401    if (!ctx->Extensions.EXT_paletted_texture && _mesa_is_index_format(format)) {
 402       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(format)");
 403       return GL_TRUE;
 404    }
 405
 406    if (!ctx->Extensions.ARB_depth_texture && _mesa_is_depth_format(format)) {
 407       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(format)");
 408       return GL_TRUE;
 409    }
 410
 411    if (!ctx->Extensions.MESA_ycbcr_texture && _mesa_is_ycbcr_format(format)) {
 412       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(format)");
 413       return GL_TRUE;
 414    }
 415
 416    if (!ctx->Extensions.EXT_packed_depth_stencil
 417        && _mesa_is_depthstencil_format(format)) {
 418       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(format)");
 419       return GL_TRUE;
 420    }
 421
 422    if (!ctx->Extensions.ATI_envmap_bumpmap
 423        && _mesa_is_dudv_format(format)) {
 424       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(format)");
 425       return GL_TRUE;
 426    }
 427
 428    texUnit = _mesa_get_current_tex_unit(ctx);
 429    texObj = _mesa_select_tex_object(ctx, texUnit, target);
 430
 431    if (!texObj || _mesa_is_proxy_texture(target)) {
 432       _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexImage(target)");
 433       return GL_TRUE;
 434    }
 435
 436    texImage = _mesa_select_tex_image(ctx, texObj, target, level);
 437    if (!texImage) {
 438       /* out of memory */
 439       return GL_TRUE;
 440    }
 441
 442    baseFormat = _mesa_get_format_base_format(texImage->TexFormat);
 443
 444    /* Make sure the requested image format is compatible with the
 445     * texture's format.  Note that a color index texture can be converted
 446     * to RGBA so that combo is allowed.
 447     */
 448    if (_mesa_is_color_format(format)
 449        && !_mesa_is_color_format(baseFormat)
 450        && !_mesa_is_index_format(baseFormat)) {
 451       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 452       return GL_TRUE;
 453    }
 454    else if (_mesa_is_index_format(format)
 455             && !_mesa_is_index_format(baseFormat)) {
 456       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 457       return GL_TRUE;
 458    }
 459    else if (_mesa_is_depth_format(format)
 460             && !_mesa_is_depth_format(baseFormat)
 461             && !_mesa_is_depthstencil_format(baseFormat)) {
 462       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 463       return GL_TRUE;
 464    }
 465    else if (_mesa_is_ycbcr_format(format)
 466             && !_mesa_is_ycbcr_format(baseFormat)) {
 467       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 468       return GL_TRUE;
 469    }
 470    else if (_mesa_is_depthstencil_format(format)
 471             && !_mesa_is_depthstencil_format(baseFormat)) {
 472       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 473       return GL_TRUE;
 474    }
 475    else if (_mesa_is_dudv_format(format)
 476             && !_mesa_is_dudv_format(baseFormat)) {
 477       _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexImage(format mismatch)");
 478       return GL_TRUE;
 479    }
 480
 481    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
 482       /* packing texture image into a PBO */
 483       const GLuint dimensions = (target == GL_TEXTURE_3D) ? 3 : 2;
 484       if (!_mesa_validate_pbo_access(dimensions, &ctx->Pack, texImage->Width,
 485                                      texImage->Height, texImage->Depth,
 486                                      format, type, pixels)) {
 487          _mesa_error(ctx, GL_INVALID_OPERATION,
 488                      "glGetTexImage(invalid PBO access)");
 489          return GL_TRUE;
 490       }
 491    }
 492
 493    return GL_FALSE;
 494 }
 495
 496
 497
 498 /**
 499  * Get texture image.  Called by glGetTexImage.
 500  *
 501  * \param target texture target.
 502  * \param level image level.
 503  * \param format pixel data format for returned image.
 504  * \param type pixel data type for returned image.
 505  * \param pixels returned pixel data.
 506  */
 507 void GLAPIENTRY
 508 _mesa_GetTexImage( GLenum target, GLint level, GLenum format,
 509                    GLenum type, GLvoid *pixels )
 510 {
 511    const struct gl_texture_unit *texUnit;
 512    struct gl_texture_object *texObj;
 513    GET_CURRENT_CONTEXT(ctx);
 514    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 515
 516    if (getteximage_error_check(ctx, target, level, format, type, pixels)) {
 517       return;
 518    }
 519
 520    texUnit = _mesa_get_current_tex_unit(ctx);
 521    texObj = _mesa_select_tex_object(ctx, texUnit, target);
 522
 523    _mesa_lock_texture(ctx, texObj);
 524    {
 525       struct gl_texture_image *texImage =
 526          _mesa_select_tex_image(ctx, texObj, target, level);
 527
 528       /* typically, this will call _mesa_get_teximage() */
 529       ctx->Driver.GetTexImage(ctx, target, level, format, type, pixels,
 530                               texObj, texImage);
 531    }
 532    _mesa_unlock_texture(ctx, texObj);
 533 }
 534
 535
 536 void GLAPIENTRY
 537 _mesa_GetCompressedTexImageARB(GLenum target, GLint level, GLvoid *img)
 538 {
 539    const struct gl_texture_unit *texUnit;
 540    struct gl_texture_object *texObj;
 541    struct gl_texture_image *texImage;
 542    GLint maxLevels;
 543    GET_CURRENT_CONTEXT(ctx);
 544    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 545
 546    texUnit = _mesa_get_current_tex_unit(ctx);
 547    texObj = _mesa_select_tex_object(ctx, texUnit, target);
 548    if (!texObj) {
 549       _mesa_error(ctx, GL_INVALID_ENUM, "glGetCompressedTexImageARB");
 550       return;
 551    }
 552
 553    maxLevels = _mesa_max_texture_levels(ctx, target);
 554    ASSERT(maxLevels > 0); /* 0 indicates bad target, caught above */
 555
 556    if (level < 0 || level >= maxLevels) {
 557       _mesa_error(ctx, GL_INVALID_VALUE, "glGetCompressedTexImageARB(level)");
 558       return;
 559    }
 560
 561    if (_mesa_is_proxy_texture(target)) {
 562       _mesa_error(ctx, GL_INVALID_ENUM, "glGetCompressedTexImageARB(target)");
 563       return;
 564    }
 565
 566    _mesa_lock_texture(ctx, texObj);
 567    {
 568       texImage = _mesa_select_tex_image(ctx, texObj, target, level);
 569       if (texImage) {
 570          if (_mesa_is_format_compressed(texImage->TexFormat)) {
 571             /* this typically calls _mesa_get_compressed_teximage() */
 572             ctx->Driver.GetCompressedTexImage(ctx, target, level, img,
 573                                               texObj, texImage);
 574          }
 575          else {
 576             _mesa_error(ctx, GL_INVALID_OPERATION,
 577                         "glGetCompressedTexImageARB");
 578          }
 579       }
 580       else {
 581          /* probably invalid mipmap level */
 582          _mesa_error(ctx, GL_INVALID_VALUE,
 583                      "glGetCompressedTexImageARB(level)");
 584       }
 585    }
 586    _mesa_unlock_texture(ctx, texObj);
 587 }