src/mesa/swrast/s_readpix.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.2
   4  *
   5  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 #include "glheader.h"
  27 #include "bufferobj.h"
  28 #include "colormac.h"
  29 #include "convolve.h"
  30 #include "context.h"
  31 #include "feedback.h"
  32 #include "image.h"
  33 #include "macros.h"
  34 #include "imports.h"
  35 #include "pixel.h"
  36 #include "state.h"
  37
  38 #include "s_context.h"
  39 #include "s_depth.h"
  40 #include "s_span.h"
  41 #include "s_stencil.h"
  42
  43
  44 /*
  45  * Read a block of color index pixels.
  46  */
  47 static void
  48 read_index_pixels( GLcontext *ctx,
  49                    GLint x, GLint y,
  50                    GLsizei width, GLsizei height,
  51                    GLenum type, GLvoid *pixels,
  52                    const struct gl_pixelstore_attrib *packing )
  53 {
  54    struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
  55    GLint i;
  56
  57    ASSERT(rb);
  58
  59    /* width should never be > MAX_WIDTH since we did clipping earlier */
  60    ASSERT(width <= MAX_WIDTH);
  61
  62    /* process image row by row */
  63    for (i = 0; i < height; i++) {
  64       GLuint index[MAX_WIDTH];
  65       GLvoid *dest;
  66       ASSERT(rb->DataType == GL_UNSIGNED_INT);
  67       rb->GetRow(ctx, rb, width, x, y + i, index);
  68
  69       dest = _mesa_image_address2d(packing, pixels, width, height,
  70                                    GL_COLOR_INDEX, type, i, 0);
  71
  72       _mesa_pack_index_span(ctx, width, type, dest, index,
  73                             &ctx->Pack, ctx->_ImageTransferState);
  74    }
  75 }
  76
  77
  78
  79 /**
  80  * Read pixels for format=GL_DEPTH_COMPONENT.
  81  */
  82 static void
  83 read_depth_pixels( GLcontext *ctx,
  84                    GLint x, GLint y,
  85                    GLsizei width, GLsizei height,
  86                    GLenum type, GLvoid *pixels,
  87                    const struct gl_pixelstore_attrib *packing )
  88 {
  89    struct gl_framebuffer *fb = ctx->ReadBuffer;
  90    struct gl_renderbuffer *rb = fb->_DepthBuffer;
  91    const GLboolean biasOrScale
  92       = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
  93
  94    /* clipping should have been done already */
  95    ASSERT(x >= 0);
  96    ASSERT(y >= 0);
  97    ASSERT(x + width <= rb->Width);
  98    ASSERT(y + height <= rb->Height);
  99    /* width should never be > MAX_WIDTH since we did clipping earlier */
 100    ASSERT(width <= MAX_WIDTH);
 101
 102    ASSERT(rb);
 103
 104    if (type == GL_UNSIGNED_SHORT && fb->Visual.depthBits == 16
 105        && !biasOrScale && !packing->SwapBytes) {
 106       /* Special case: directly read 16-bit unsigned depth values. */
 107       GLint j;
 108       ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT16);
 109       ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
 110       for (j = 0; j < height; j++, y++) {
 111          void *dest =_mesa_image_address2d(packing, pixels, width, height,
 112                                            GL_DEPTH_COMPONENT, type, j, 0);
 113          rb->GetRow(ctx, rb, width, x, y, dest);
 114       }
 115    }
 116    else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 24
 117             && !biasOrScale && !packing->SwapBytes) {
 118       /* Special case: directly read 24-bit unsigned depth values. */
 119       GLint j;
 120       ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT32);
 121       ASSERT(rb->DataType == GL_UNSIGNED_INT);
 122       for (j = 0; j < height; j++, y++) {
 123          GLuint *dest = (GLuint *)
 124             _mesa_image_address2d(packing, pixels, width, height,
 125                                   GL_DEPTH_COMPONENT, type, j, 0);
 126          GLint k;
 127          rb->GetRow(ctx, rb, width, x, y, dest);
 128          /* convert range from 24-bit to 32-bit */
 129          for (k = 0; k < width; k++) {
 130             dest[k] = (dest[k] << 8) | (dest[k] >> 24);
 131          }
 132       }
 133    }
 134    else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 32
 135             && !biasOrScale && !packing->SwapBytes) {
 136       /* Special case: directly read 32-bit unsigned depth values. */
 137       GLint j;
 138       ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT32);
 139       ASSERT(rb->DataType == GL_UNSIGNED_INT);
 140       for (j = 0; j < height; j++, y++) {
 141          void *dest = _mesa_image_address2d(packing, pixels, width, height,
 142                                             GL_DEPTH_COMPONENT, type, j, 0);
 143          rb->GetRow(ctx, rb, width, x, y, dest);
 144       }
 145    }
 146    else {
 147       /* General case (slower) */
 148       GLint j;
 149       for (j = 0; j < height; j++, y++) {
 150          GLfloat depthValues[MAX_WIDTH];
 151          GLvoid *dest = _mesa_image_address2d(packing, pixels, width, height,
 152                                               GL_DEPTH_COMPONENT, type, j, 0);
 153          _swrast_read_depth_span_float(ctx, rb, width, x, y, depthValues);
 154          _mesa_pack_depth_span(ctx, width, dest, type, depthValues, packing);
 155       }
 156    }
 157 }
 158
 159
 160 /**
 161  * Read pixels for format=GL_STENCIL_INDEX.
 162  */
 163 static void
 164 read_stencil_pixels( GLcontext *ctx,
 165                      GLint x, GLint y,
 166                      GLsizei width, GLsizei height,
 167                      GLenum type, GLvoid *pixels,
 168                      const struct gl_pixelstore_attrib *packing )
 169 {
 170    struct gl_framebuffer *fb = ctx->ReadBuffer;
 171    struct gl_renderbuffer *rb = fb->_StencilBuffer;
 172    GLint j;
 173
 174    ASSERT(rb);
 175
 176    /* width should never be > MAX_WIDTH since we did clipping earlier */
 177    ASSERT(width <= MAX_WIDTH);
 178
 179    /* process image row by row */
 180    for (j=0;j<height;j++,y++) {
 181       GLvoid *dest;
 182       GLstencil stencil[MAX_WIDTH];
 183
 184       _swrast_read_stencil_span(ctx, rb, width, x, y, stencil);
 185
 186       dest = _mesa_image_address2d(packing, pixels, width, height,
 187                                    GL_STENCIL_INDEX, type, j, 0);
 188
 189       _mesa_pack_stencil_span(ctx, width, type, dest, stencil, packing);
 190    }
 191 }
 192
 193
 194
 195 /**
 196  * Optimized glReadPixels for particular pixel formats when pixel
 197  * scaling, biasing, mapping, etc. are disabled.
 198  */
 199 static GLboolean
 200 fast_read_rgba_pixels( GLcontext *ctx,
 201                        GLint x, GLint y,
 202                        GLsizei width, GLsizei height,
 203                        GLenum format, GLenum type,
 204                        GLvoid *pixels,
 205                        const struct gl_pixelstore_attrib *packing )
 206 {
 207    struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
 208
 209    ASSERT(rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB);
 210
 211    /* clipping should have already been done */
 212    ASSERT(x + width <= rb->Width);
 213    ASSERT(y + height <= rb->Height);
 214
 215    /* check for things we can't handle here */
 216    if (ctx->_ImageTransferState ||
 217        packing->SwapBytes ||
 218        packing->LsbFirst) {
 219       return GL_FALSE;
 220    }
 221
 222    if (format == GL_RGBA && rb->DataType == type) {
 223       const GLint dstStride = _mesa_image_row_stride(packing, width,
 224                                                      format, type);
 225       GLubyte *dest = _mesa_image_address2d(packing, pixels, width, height,
 226                                             format, type, 0, 0);
 227       GLint row;
 228       ASSERT(rb->GetRow);
 229       for (row = 0; row < height; row++) {
 230          rb->GetRow(ctx, rb, width, x, y + row, dest);
 231          dest += dstStride;
 232       }
 233       return GL_TRUE;
 234    }
 235
 236    if (format == GL_RGB &&
 237        rb->DataType == GL_UNSIGNED_BYTE &&
 238        type == GL_UNSIGNED_BYTE) {
 239       const GLint dstStride = _mesa_image_row_stride(packing, width,
 240                                                      format, type);
 241       GLubyte *dest = _mesa_image_address2d(packing, pixels, width, height,
 242                                             format, type, 0, 0);
 243       GLint row;
 244       ASSERT(rb->GetRow);
 245       for (row = 0; row < height; row++) {
 246          GLubyte tempRow[MAX_WIDTH][4];
 247          GLint col;
 248          rb->GetRow(ctx, rb, width, x, y + row, tempRow);
 249          /* convert RGBA to RGB */
 250          for (col = 0; col < width; col++) {
 251             dest[col * 3 + 0] = tempRow[col][0];
 252             dest[col * 3 + 1] = tempRow[col][1];
 253             dest[col * 3 + 2] = tempRow[col][2];
 254          }
 255          dest += dstStride;
 256       }
 257       return GL_TRUE;
 258    }
 259
 260    /* not handled */
 261    return GL_FALSE;
 262 }
 263
 264
 265
 266 /*
 267  * Read R, G, B, A, RGB, L, or LA pixels.
 268  */
 269 static void
 270 read_rgba_pixels( GLcontext *ctx,
 271                   GLint x, GLint y,
 272                   GLsizei width, GLsizei height,
 273                   GLenum format, GLenum type, GLvoid *pixels,
 274                   const struct gl_pixelstore_attrib *packing )
 275 {
 276    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 277    struct gl_framebuffer *fb = ctx->ReadBuffer;
 278    struct gl_renderbuffer *rb = fb->_ColorReadBuffer;
 279
 280    ASSERT(rb);
 281
 282    /* Try optimized path first */
 283    if (fast_read_rgba_pixels(ctx, x, y, width, height,
 284                              format, type, pixels, packing)) {
 285       return; /* done! */
 286    }
 287
 288    /* width should never be > MAX_WIDTH since we did clipping earlier */
 289    ASSERT(width <= MAX_WIDTH);
 290
 291    if (ctx->Pixel.Convolution2DEnabled || ctx->Pixel.Separable2DEnabled) {
 292       const GLuint transferOps = ctx->_ImageTransferState;
 293       GLfloat *dest, *src, *tmpImage, *convImage;
 294       GLint row;
 295
 296       tmpImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
 297       if (!tmpImage) {
 298          _mesa_error(ctx, GL_OUT_OF_MEMORY, "glReadPixels");
 299          return;
 300       }
 301       convImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
 302       if (!convImage) {
 303          _mesa_free(tmpImage);
 304          _mesa_error(ctx, GL_OUT_OF_MEMORY, "glReadPixels");
 305          return;
 306       }
 307
 308       /* read full RGBA, FLOAT image */
 309       dest = tmpImage;
 310       for (row = 0; row < height; row++, y++) {
 311          if (fb->Visual.rgbMode) {
 312             _swrast_read_rgba_span(ctx, rb, width, x, y, GL_FLOAT, dest);
 313          }
 314          else {
 315             GLuint index[MAX_WIDTH];
 316             ASSERT(rb->DataType == GL_UNSIGNED_INT);
 317             rb->GetRow(ctx, rb, width, x, y, index);
 318             if (ctx->Pixel.IndexShift != 0 || ctx->Pixel.IndexOffset !=0 ) {
 319                _mesa_map_ci(ctx, width, index);
 320             }
 321             _mesa_map_ci_to_rgba(ctx, width, index, (GLfloat (*)[4]) dest);
 322          }
 323          _mesa_apply_rgba_transfer_ops(ctx,
 324                                       transferOps & IMAGE_PRE_CONVOLUTION_BITS,
 325                                       width, (GLfloat (*)[4]) dest);
 326          dest += width * 4;
 327       }
 328
 329       /* do convolution */
 330       if (ctx->Pixel.Convolution2DEnabled) {
 331          _mesa_convolve_2d_image(ctx, &width, &height, tmpImage, convImage);
 332       }
 333       else {
 334          ASSERT(ctx->Pixel.Separable2DEnabled);
 335          _mesa_convolve_sep_image(ctx, &width, &height, tmpImage, convImage);
 336       }
 337       _mesa_free(tmpImage);
 338
 339       /* finish transfer ops and pack the resulting image */
 340       src = convImage;
 341       for (row = 0; row < height; row++) {
 342          GLvoid *dest;
 343          dest = _mesa_image_address2d(packing, pixels, width, height,
 344                                       format, type, row, 0);
 345          _mesa_pack_rgba_span_float(ctx, width,
 346                                     (const GLfloat (*)[4]) src,
 347                                     format, type, dest, packing,
 348                                     transferOps & IMAGE_POST_CONVOLUTION_BITS);
 349          src += width * 4;
 350       }
 351       _mesa_free(convImage);
 352    }
 353    else {
 354       /* no convolution */
 355       const GLint dstStride
 356          = _mesa_image_row_stride(packing, width, format, type);
 357       GLfloat (*rgba)[4] = swrast->SpanArrays->color.sz4.rgba;
 358       GLint row;
 359       GLubyte *dst = _mesa_image_address2d(packing, pixels, width, height,
 360                                            format, type, 0, 0);
 361
 362       for (row = 0; row < height; row++, y++) {
 363
 364          /* Get float rgba pixels */
 365          if (fb->Visual.rgbMode) {
 366             _swrast_read_rgba_span(ctx, rb, width, x, y, GL_FLOAT, rgba);
 367          }
 368          else {
 369             /* read CI and convert to RGBA */
 370             GLuint index[MAX_WIDTH];
 371             ASSERT(rb->DataType == GL_UNSIGNED_INT);
 372             rb->GetRow(ctx, rb, width, x, y, index);
 373             if (ctx->Pixel.IndexShift != 0 || ctx->Pixel.IndexOffset != 0) {
 374                _mesa_map_ci(ctx, width, index);
 375             }
 376             _mesa_map_ci_to_rgba(ctx, width, index, rgba);
 377          }
 378
 379          /* pack the row of RGBA pixels into user's buffer */
 380 #if 0
 381          /* XXX may need to rejuvinate this code if we get conformance
 382           * falures on 16bpp displays (i.e. 5/6/5).
 383           */
 384          if (fb->Visual.redBits < CHAN_BITS ||
 385              fb->Visual.greenBits < CHAN_BITS ||
 386              fb->Visual.blueBits < CHAN_BITS) {
 387             /* Requantize the color values into floating point and go from
 388              * there.  This fixes conformance failures with 5/6/5 color
 389              * buffers, for example.
 390              */
 391             GLfloat rgbaf[MAX_WIDTH][4];
 392             _mesa_chan_to_float_span(ctx, width,
 393                                      (CONST GLchan (*)[4]) rgba, rgbaf);
 394             _mesa_pack_rgba_span_float(ctx, width,
 395                                        (CONST GLfloat (*)[4]) rgbaf,
 396                                        format, type, dst, packing,
 397                                        ctx->_ImageTransferState);
 398          }
 399          else
 400 #endif
 401          {
 402             _mesa_pack_rgba_span_float(ctx, width, (CONST GLfloat (*)[4]) rgba,
 403                                        format, type, dst,
 404                                        packing, ctx->_ImageTransferState);
 405          }
 406
 407          dst += dstStride;
 408       }
 409    }
 410 }
 411
 412
 413 /**
 414  * Read combined depth/stencil values.
 415  * We'll have already done error checking to be sure the expected
 416  * depth and stencil buffers really exist.
 417  */
 418 static void
 419 read_depth_stencil_pixels(GLcontext *ctx,
 420                           GLint x, GLint y,
 421                           GLsizei width, GLsizei height,
 422                           GLenum type, GLvoid *pixels,
 423                           const struct gl_pixelstore_attrib *packing )
 424 {
 425    const GLboolean scaleOrBias
 426       = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
 427    const GLboolean stencilTransfer = ctx->Pixel.IndexShift
 428       || ctx->Pixel.IndexOffset || ctx->Pixel.MapStencilFlag;
 429    struct gl_renderbuffer *depthRb, *stencilRb;
 430
 431    depthRb = ctx->ReadBuffer->_DepthBuffer;
 432    stencilRb = ctx->ReadBuffer->_StencilBuffer;
 433
 434    ASSERT(depthRb);
 435    ASSERT(stencilRb);
 436
 437    depthRb = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
 438    stencilRb = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
 439
 440    if (depthRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
 441        stencilRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
 442        depthRb == stencilRb &&
 443        !scaleOrBias &&
 444        !stencilTransfer) {
 445       /* This is the ideal case.
 446        * Reading GL_DEPTH_STENCIL pixels from combined depth/stencil buffer.
 447        * Plus, no pixel transfer ops to worry about!
 448        */
 449       GLint i;
 450       GLint dstStride = _mesa_image_row_stride(packing, width,
 451                                                GL_DEPTH_STENCIL_EXT, type);
 452       GLubyte *dst = (GLubyte *) _mesa_image_address2d(packing, pixels,
 453                                                        width, height,
 454                                                        GL_DEPTH_STENCIL_EXT,
 455                                                        type, 0, 0);
 456       for (i = 0; i < height; i++) {
 457          depthRb->GetRow(ctx, depthRb, width, x, y + i, dst);
 458          dst += dstStride;
 459       }
 460    }
 461    else {
 462       /* Reading GL_DEPTH_STENCIL pixels from separate depth/stencil buffers,
 463        * or we need pixel transfer.
 464        */
 465       GLint i;
 466       depthRb = ctx->ReadBuffer->_DepthBuffer;
 467       stencilRb = ctx->ReadBuffer->_StencilBuffer;
 468
 469       for (i = 0; i < height; i++) {
 470          GLstencil stencilVals[MAX_WIDTH];
 471
 472          GLuint *depthStencilDst = (GLuint *)
 473             _mesa_image_address2d(packing, pixels, width, height,
 474                                   GL_DEPTH_STENCIL_EXT, type, i, 0);
 475
 476          _swrast_read_stencil_span(ctx, stencilRb, width,
 477                                    x, y + i, stencilVals);
 478
 479          if (!scaleOrBias && !stencilTransfer
 480              && ctx->ReadBuffer->Visual.depthBits == 24) {
 481             /* ideal case */
 482             GLuint zVals[MAX_WIDTH]; /* 24-bit values! */
 483             GLint j;
 484             ASSERT(depthRb->DataType == GL_UNSIGNED_INT);
 485             /* note, we've already been clipped */
 486             depthRb->GetRow(ctx, depthRb, width, x, y + i, zVals);
 487             for (j = 0; j < width; j++) {
 488                depthStencilDst[j] = (zVals[j] << 8) | (stencilVals[j] & 0xff);
 489             }
 490          }
 491          else {
 492             /* general case */
 493             GLfloat depthVals[MAX_WIDTH];
 494             _swrast_read_depth_span_float(ctx, depthRb, width, x, y + i,
 495                                           depthVals);
 496             _mesa_pack_depth_stencil_span(ctx, width, depthStencilDst,
 497                                           depthVals, stencilVals, packing);
 498          }
 499       }
 500    }
 501 }
 502
 503
 504
 505 /**
 506  * Software fallback routine for ctx->Driver.ReadPixels().
 507  * By time we get here, all error checking will have been done.
 508  */
 509 void
 510 _swrast_ReadPixels( GLcontext *ctx,
 511                     GLint x, GLint y, GLsizei width, GLsizei height,
 512                     GLenum format, GLenum type,
 513                     const struct gl_pixelstore_attrib *packing,
 514                     GLvoid *pixels )
 515 {
 516    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 517    struct gl_pixelstore_attrib clippedPacking = *packing;
 518
 519    /* Need to do RENDER_START before clipping or anything else since this
 520     * is where a driver may grab the hw lock and get an updated window
 521     * size.
 522     */
 523    RENDER_START(swrast, ctx);
 524
 525    if (ctx->NewState)
 526       _mesa_update_state(ctx);
 527
 528    if (swrast->NewState)
 529       _swrast_validate_derived( ctx );
 530
 531    /* Do all needed clipping here, so that we can forget about it later */
 532    if (!_mesa_clip_readpixels(ctx, &x, &y, &width, &height, &clippedPacking)) {
 533       /* The ReadPixels region is totally outside the window bounds */
 534       return;
 535    }
 536
 537    if (clippedPacking.BufferObj->Name) {
 538       /* pack into PBO */
 539       GLubyte *buf;
 540       if (!_mesa_validate_pbo_access(2, &clippedPacking, width, height, 1,
 541                                      format, type, pixels)) {
 542          _mesa_error(ctx, GL_INVALID_OPERATION,
 543                      "glReadPixels(invalid PBO access)");
 544          goto end;
 545       }
 546       buf = (GLubyte *) ctx->Driver.MapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 547                                               GL_WRITE_ONLY_ARB,
 548                                               clippedPacking.BufferObj);
 549       if (!buf) {
 550          /* buffer is already mapped - that's an error */
 551          _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(PBO is mapped)");
 552          goto end;
 553       }
 554       pixels = ADD_POINTERS(buf, pixels);
 555    }
 556
 557    switch (format) {
 558       case GL_COLOR_INDEX:
 559          read_index_pixels(ctx, x, y, width, height, type, pixels,
 560                            &clippedPacking);
 561          break;
 562       case GL_STENCIL_INDEX:
 563          read_stencil_pixels(ctx, x, y, width, height, type, pixels,
 564                              &clippedPacking);
 565          break;
 566       case GL_DEPTH_COMPONENT:
 567          read_depth_pixels(ctx, x, y, width, height, type, pixels,
 568                            &clippedPacking);
 569          break;
 570       case GL_RED:
 571       case GL_GREEN:
 572       case GL_BLUE:
 573       case GL_ALPHA:
 574       case GL_RGB:
 575       case GL_LUMINANCE:
 576       case GL_LUMINANCE_ALPHA:
 577       case GL_RGBA:
 578       case GL_BGR:
 579       case GL_BGRA:
 580       case GL_ABGR_EXT:
 581          read_rgba_pixels(ctx, x, y, width, height,
 582                           format, type, pixels, &clippedPacking);
 583          break;
 584       case GL_DEPTH_STENCIL_EXT:
 585          read_depth_stencil_pixels(ctx, x, y, width, height,
 586                                    type, pixels, &clippedPacking);
 587          break;
 588       default:
 589          _mesa_problem(ctx, "unexpected format in _swrast_ReadPixels");
 590          /* don't return yet, clean-up */
 591    }
 592
 593
 594 end:
 595    RENDER_FINISH(swrast, ctx);
 596
 597    if (clippedPacking.BufferObj->Name) {
 598       /* done with PBO so unmap it now */
 599       ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
 600                               clippedPacking.BufferObj);
 601    }
 602 }