path: root/src/mesa/main/texgetimage.c

/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
 * Copyright (c) 2009 VMware, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */


/**
 * Code for glGetTexImage() and glGetCompressedTexImage().
 */


#include "glheader.h"
#include "bufferobj.h"
#include "enums.h"
#include "context.h"
#include "formats.h"
#include "format_unpack.h"
#include "glformats.h"
#include "image.h"
#include "mtypes.h"
#include "pack.h"
#include "pbo.h"
#include "pixelstore.h"
#include "texcompress.h"
#include "texgetimage.h"
#include "teximage.h"
#include "texobj.h"
#include "texstore.h"
#include "format_utils.h"
#include "pixeltransfer.h"

/**
 * Can the given type represent negative values?
 */
static inline GLboolean
type_needs_clamping(GLenum type)
{
   switch (type) {
   case GL_BYTE:
   case GL_SHORT:
   case GL_INT:
   case GL_FLOAT:
   case GL_HALF_FLOAT_ARB:
   case GL_UNSIGNED_INT_10F_11F_11F_REV:
   case GL_UNSIGNED_INT_5_9_9_9_REV:
      return GL_FALSE;
   default:
      return GL_TRUE;
   }
}


/**
 * glGetTexImage for depth/Z pixels.
 */
static void
get_tex_depth(struct gl_context *ctx, GLuint dimensions,
              GLint xoffset, GLint yoffset, GLint zoffset,
              GLsizei width, GLsizei height, GLint depth,
              GLenum format, GLenum type, GLvoid *pixels,
              struct gl_texture_image *texImage)
{
   GLint img, row;
   GLfloat *depthRow = malloc(width * sizeof(GLfloat));

   if (!depthRow) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
      return;
   }

   if (texImage->TexObject->Target == GL_TEXTURE_1D_ARRAY) {
      depth = height;
      height = 1;
   }

   assert(zoffset + depth <= texImage->Depth);
   for (img = 0; img < depth; img++) {
      GLubyte *srcMap;
      GLint srcRowStride;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + img,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT, &srcMap, &srcRowStride);

      if (srcMap) {
         for (row = 0; row < height; row++) {
            void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                             width, height, format, type,
                                             img, row, 0);
            const GLubyte *src = srcMap + row * srcRowStride;
            _mesa_unpack_float_z_row(texImage->TexFormat, width, src, depthRow);
            _mesa_pack_depth_span(ctx, width, dest, type, depthRow, &ctx->Pack);
         }

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + img);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         break;
      }
   }

   free(depthRow);
}


/**
 * glGetTexImage for depth/stencil pixels.
 */
static void
get_tex_depth_stencil(struct gl_context *ctx, GLuint dimensions,
                      GLint xoffset, GLint yoffset, GLint zoffset,
                      GLsizei width, GLsizei height, GLint depth,
                      GLenum format, GLenum type, GLvoid *pixels,
                      struct gl_texture_image *texImage)
{
   GLint img, row;

   assert(format == GL_DEPTH_STENCIL);
   assert(type == GL_UNSIGNED_INT_24_8 ||
          type == GL_FLOAT_32_UNSIGNED_INT_24_8_REV);

   assert(zoffset + depth <= texImage->Depth);
   for (img = 0; img < depth; img++) {
      GLubyte *srcMap;
      GLint rowstride;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + img,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT, &srcMap, &rowstride);

      if (srcMap) {
         for (row = 0; row < height; row++) {
            const GLubyte *src = srcMap + row * rowstride;
            void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                             width, height, format, type,
                                             img, row, 0);
            _mesa_unpack_depth_stencil_row(texImage->TexFormat,
                                           width,
                                           (const GLuint *) src,
                                           type, dest);
            if (ctx->Pack.SwapBytes) {
               _mesa_swap4((GLuint *) dest, width);
            }
         }

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + img);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         break;
      }
   }
}

/**
 * glGetTexImage for stencil pixels.
 */
static void
get_tex_stencil(struct gl_context *ctx, GLuint dimensions,
                GLint xoffset, GLint yoffset, GLint zoffset,
                GLsizei width, GLsizei height, GLint depth,
                GLenum format, GLenum type, GLvoid *pixels,
                struct gl_texture_image *texImage)
{
   GLint img, row;

   assert(format == GL_STENCIL_INDEX);

   for (img = 0; img < depth; img++) {
      GLubyte *srcMap;
      GLint rowstride;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + img,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT,
                                  &srcMap, &rowstride);

      if (srcMap) {
         for (row = 0; row < height; row++) {
            const GLubyte *src = srcMap + row * rowstride;
            void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                             width, height, format, type,
                                             img, row, 0);
            _mesa_unpack_ubyte_stencil_row(texImage->TexFormat,
                                           width,
                                           (const GLuint *) src,
                                           dest);
         }

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + img);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         break;
      }
   }
}


/**
 * glGetTexImage for YCbCr pixels.
 */
static void
get_tex_ycbcr(struct gl_context *ctx, GLuint dimensions,
              GLint xoffset, GLint yoffset, GLint zoffset,
              GLsizei width, GLsizei height, GLint depth,
              GLenum format, GLenum type, GLvoid *pixels,
              struct gl_texture_image *texImage)
{
   GLint img, row;

   assert(zoffset + depth <= texImage->Depth);
   for (img = 0; img < depth; img++) {
      GLubyte *srcMap;
      GLint rowstride;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + img,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT, &srcMap, &rowstride);

      if (srcMap) {
         for (row = 0; row < height; row++) {
            const GLubyte *src = srcMap + row * rowstride;
            void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                             width, height, format, type,
                                             img, row, 0);
            memcpy(dest, src, width * sizeof(GLushort));

            /* check for byte swapping */
            if ((texImage->TexFormat == MESA_FORMAT_YCBCR
                 && type == GL_UNSIGNED_SHORT_8_8_REV_MESA) ||
                (texImage->TexFormat == MESA_FORMAT_YCBCR_REV
                 && type == GL_UNSIGNED_SHORT_8_8_MESA)) {
               if (!ctx->Pack.SwapBytes)
                  _mesa_swap2((GLushort *) dest, width);
            }
            else if (ctx->Pack.SwapBytes) {
               _mesa_swap2((GLushort *) dest, width);
            }
         }

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + img);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         break;
      }
   }
}


/**
 * Get a color texture image with decompression.
 */
static void
get_tex_rgba_compressed(struct gl_context *ctx, GLuint dimensions,
                        GLint xoffset, GLint yoffset, GLint zoffset,
                        GLsizei width, GLsizei height, GLint depth,
                        GLenum format, GLenum type, GLvoid *pixels,
                        struct gl_texture_image *texImage,
                        GLbitfield transferOps)
{
   /* don't want to apply sRGB -> RGB conversion here so override the format */
   const mesa_format texFormat =
      _mesa_get_srgb_format_linear(texImage->TexFormat);
   const GLenum baseFormat = _mesa_get_format_base_format(texFormat);
   GLfloat *tempImage, *tempSlice;
   GLuint slice;
   int srcStride, dstStride;
   uint32_t dstFormat;
   bool needsRebase;
   uint8_t rebaseSwizzle[4];

   /* Decompress into temp float buffer, then pack into user buffer */
   tempImage = malloc(width * height * depth
                                  * 4 * sizeof(GLfloat));
   if (!tempImage) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage()");
      return;
   }

   /* Decompress the texture image slices - results in 'tempImage' */
   for (slice = 0; slice < depth; slice++) {
      GLubyte *srcMap;
      GLint srcRowStride;

      tempSlice = tempImage + slice * 4 * width * height;

      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + slice,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT,
                                  &srcMap, &srcRowStride);
      if (srcMap) {
         _mesa_decompress_image(texFormat, width, height,
                                srcMap, srcRowStride, tempSlice);

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + slice);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         free(tempImage);
         return;
      }
   }

   /* Depending on the base format involved we may need to apply a rebase
    * transform (for example: if we download to a Luminance format we want
    * G=0 and B=0).
    */
   if (baseFormat == GL_LUMINANCE ||
       baseFormat == GL_INTENSITY) {
      needsRebase = true;
      rebaseSwizzle[0] = MESA_FORMAT_SWIZZLE_X;
      rebaseSwizzle[1] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[2] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[3] = MESA_FORMAT_SWIZZLE_ONE;
   } else if (baseFormat == GL_LUMINANCE_ALPHA) {
      needsRebase = true;
      rebaseSwizzle[0] = MESA_FORMAT_SWIZZLE_X;
      rebaseSwizzle[1] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[2] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[3] = MESA_FORMAT_SWIZZLE_W;
   } else {
      needsRebase = false;
   }

   srcStride = 4 * width * sizeof(GLfloat);
   dstStride = _mesa_image_row_stride(&ctx->Pack, width, format, type);
   dstFormat = _mesa_format_from_format_and_type(format, type);
   tempSlice = tempImage;
   for (slice = 0; slice < depth; slice++) {
      void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                       width, height, format, type,
                                       slice, 0, 0);
      _mesa_format_convert(dest, dstFormat, dstStride,
                           tempSlice, RGBA32_FLOAT, srcStride,
                           width, height,
                           needsRebase ? rebaseSwizzle : NULL);
      tempSlice += 4 * width * height;
   }

   free(tempImage);
}


/**
 * Return a base GL format given the user-requested format
 * for glGetTexImage().
 */
GLenum
_mesa_base_pack_format(GLenum format)
{
   switch (format) {
   case GL_ABGR_EXT:
   case GL_BGRA:
   case GL_BGRA_INTEGER:
   case GL_RGBA_INTEGER:
      return GL_RGBA;
   case GL_BGR:
   case GL_BGR_INTEGER:
   case GL_RGB_INTEGER:
      return GL_RGB;
   case GL_RED_INTEGER:
      return GL_RED;
   case GL_GREEN_INTEGER:
      return GL_GREEN;
   case GL_BLUE_INTEGER:
      return GL_BLUE;
   case GL_ALPHA_INTEGER:
      return GL_ALPHA;
   case GL_LUMINANCE_INTEGER_EXT:
      return GL_LUMINANCE;
   case GL_LUMINANCE_ALPHA_INTEGER_EXT:
      return GL_LUMINANCE_ALPHA;
   default:
      return format;
   }
}


/**
 * Get an uncompressed color texture image.
 */
static void
get_tex_rgba_uncompressed(struct gl_context *ctx, GLuint dimensions,
                          GLint xoffset, GLint yoffset, GLint zoffset,
                          GLsizei width, GLsizei height, GLint depth,
                          GLenum format, GLenum type, GLvoid *pixels,
                          struct gl_texture_image *texImage,
                          GLbitfield transferOps)
{
   /* don't want to apply sRGB -> RGB conversion here so override the format */
   const mesa_format texFormat =
      _mesa_get_srgb_format_linear(texImage->TexFormat);
   GLuint img;
   GLboolean dst_is_integer;
   uint32_t dst_format;
   int dst_stride;
   uint8_t rebaseSwizzle[4];
   bool needsRebase;
   void *rgba = NULL;

   if (texImage->TexObject->Target == GL_TEXTURE_1D_ARRAY) {
      depth = height;
      height = 1;
      zoffset = yoffset;
      yoffset = 0;
   }

   /* Depending on the base format involved we may need to apply a rebase
    * transform (for example: if we download to a Luminance format we want
    * G=0 and B=0).
    */
   if (texImage->_BaseFormat == GL_LUMINANCE ||
       texImage->_BaseFormat == GL_INTENSITY) {
      needsRebase = true;
      rebaseSwizzle[0] = MESA_FORMAT_SWIZZLE_X;
      rebaseSwizzle[1] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[2] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[3] = MESA_FORMAT_SWIZZLE_ONE;
   } else if (texImage->_BaseFormat == GL_LUMINANCE_ALPHA) {
      needsRebase = true;
      rebaseSwizzle[0] = MESA_FORMAT_SWIZZLE_X;
      rebaseSwizzle[1] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[2] = MESA_FORMAT_SWIZZLE_ZERO;
      rebaseSwizzle[3] = MESA_FORMAT_SWIZZLE_W;
    } else if (texImage->_BaseFormat != _mesa_get_format_base_format(texFormat)) {
      needsRebase =
         _mesa_compute_rgba2base2rgba_component_mapping(texImage->_BaseFormat,
                                                        rebaseSwizzle);
    } else {
      needsRebase = false;
    }

   /* Describe the dst format */
   dst_is_integer = _mesa_is_enum_format_integer(format);
   dst_format = _mesa_format_from_format_and_type(format, type);
   dst_stride = _mesa_image_row_stride(&ctx->Pack, width, format, type);

   /* Since _mesa_format_convert does not handle transferOps we need to handle
    * them before we call the function. This requires to convert to RGBA float
    * first so we can call _mesa_apply_rgba_transfer_ops. If the dst format is
    * integer then transferOps do not apply.
    */
   assert(!transferOps || (transferOps && !dst_is_integer));
   (void) dst_is_integer; /* silence unused var warning */

   for (img = 0; img < depth; img++) {
      GLubyte *srcMap;
      GLint rowstride;
      GLubyte *img_src;
      void *dest;
      void *src;
      int src_stride;
      uint32_t src_format;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + img,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT,
                                  &srcMap, &rowstride);
      if (!srcMap) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
         goto done;
      }

      img_src = srcMap;
      dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                 width, height, format, type,
                                 img, 0, 0);

      if (transferOps) {
         uint32_t rgba_format;
         int rgba_stride;
         bool need_convert = false;

         /* We will convert to RGBA float */
         rgba_format = RGBA32_FLOAT;
         rgba_stride = width * 4 * sizeof(GLfloat);

         /* If we are lucky and the dst format matches the RGBA format we need
          * to convert to, then we can convert directly into the dst buffer
          * and avoid the final conversion/copy from the rgba buffer to the dst
          * buffer.
          */
         if (format == rgba_format) {
            rgba = dest;
         } else if (rgba == NULL) { /* Allocate the RGBA buffer only once */
            need_convert = true;
            rgba = malloc(height * rgba_stride);
            if (!rgba) {
               _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage()");
               ctx->Driver.UnmapTextureImage(ctx, texImage, img);
               return;
            }
         }

         _mesa_format_convert(rgba, rgba_format, rgba_stride,
                              img_src, texFormat, rowstride,
                              width, height,
                              needsRebase ? rebaseSwizzle : NULL);

         /* Handle transfer ops now */
         _mesa_apply_rgba_transfer_ops(ctx, transferOps, width * height, rgba);

         /* If we had to rebase, we have already handled that */
         needsRebase = false;

         /* If we were lucky and our RGBA conversion matches the dst format, then
          * we are done.
          */
         if (!need_convert)
            goto do_swap;

         /* Otherwise, we need to convert from RGBA to dst next */
         src = rgba;
         src_format = rgba_format;
         src_stride = rgba_stride;
      } else {
         /* No RGBA conversion needed, convert directly to dst */
         src = img_src;
         src_format = texFormat;
         src_stride = rowstride;
      }

      /* Do the conversion to destination format */
      _mesa_format_convert(dest, dst_format, dst_stride,
                           src, src_format, src_stride,
                           width, height,
                           needsRebase ? rebaseSwizzle : NULL);

   do_swap:
      /* Handle byte swapping if required */
      if (ctx->Pack.SwapBytes) {
         GLint swapSize = _mesa_sizeof_packed_type(type);
         if (swapSize == 2 || swapSize == 4) {
            int swapsPerPixel = _mesa_bytes_per_pixel(format, type) / swapSize;
            assert(_mesa_bytes_per_pixel(format, type) % swapSize == 0);
            if (swapSize == 2)
               _mesa_swap2((GLushort *) dest, width * height * swapsPerPixel);
            else if (swapSize == 4)
               _mesa_swap4((GLuint *) dest, width * height * swapsPerPixel);
         }
      }

      /* Unmap the src texture buffer */
      ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + img);
   }

done:
   if (rgba)
      free(rgba);
}


/**
 * glGetTexImage for color formats (RGBA, RGB, alpha, LA, etc).
 * Compressed textures are handled here as well.
 */
static void
get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
             GLint xoffset, GLint yoffset, GLint zoffset,
             GLsizei width, GLsizei height, GLint depth,
             GLenum format, GLenum type, GLvoid *pixels,
             struct gl_texture_image *texImage)
{
   const GLenum dataType = _mesa_get_format_datatype(texImage->TexFormat);
   GLbitfield transferOps = 0x0;

   /* In general, clamping does not apply to glGetTexImage, except when
    * the returned type of the image can't hold negative values.
    */
   if (type_needs_clamping(type)) {
      /* the returned image type can't have negative values */
      if (dataType == GL_FLOAT ||
          dataType == GL_HALF_FLOAT ||
          dataType == GL_SIGNED_NORMALIZED ||
          format == GL_LUMINANCE ||
          format == GL_LUMINANCE_ALPHA) {
         transferOps |= IMAGE_CLAMP_BIT;
      }
   }

   if (_mesa_is_format_compressed(texImage->TexFormat)) {
      get_tex_rgba_compressed(ctx, dimensions,
                              xoffset, yoffset, zoffset,
                              width, height, depth,
                              format, type,
                              pixels, texImage, transferOps);
   }
   else {
      get_tex_rgba_uncompressed(ctx, dimensions,
                                xoffset, yoffset, zoffset,
                                width, height, depth,
                                format, type,
                                pixels, texImage, transferOps);
   }
}


/**
 * Try to do glGetTexImage() with simple memcpy().
 * \return GL_TRUE if done, GL_FALSE otherwise
 */
static GLboolean
get_tex_memcpy(struct gl_context *ctx,
               GLint xoffset, GLint yoffset, GLint zoffset,
               GLsizei width, GLsizei height, GLint depth,
               GLenum format, GLenum type, GLvoid *pixels,
               struct gl_texture_image *texImage)
{
   const GLenum target = texImage->TexObject->Target;
   GLboolean memCopy = GL_FALSE;
   GLenum texBaseFormat = _mesa_get_format_base_format(texImage->TexFormat);

   /*
    * Check if we can use memcpy to copy from the hardware texture
    * format to the user's format/type.
    * Note that GL's pixel transfer ops don't apply to glGetTexImage()
    */
   if ((target == GL_TEXTURE_1D ||
        target == GL_TEXTURE_2D ||
        target == GL_TEXTURE_RECTANGLE ||
        _mesa_is_cube_face(target)) &&
       texBaseFormat == texImage->_BaseFormat) {
      memCopy = _mesa_format_matches_format_and_type(texImage->TexFormat,
                                                     format, type,
                                                     ctx->Pack.SwapBytes);
   }

   if (depth > 1) {
      /* only a single slice is supported at this time */
      memCopy = FALSE;
   }

   if (memCopy) {
      const GLuint bpp = _mesa_get_format_bytes(texImage->TexFormat);
      const GLint bytesPerRow = width * bpp;
      GLubyte *dst =
         _mesa_image_address2d(&ctx->Pack, pixels, width, height,
                               format, type, 0, 0);
      const GLint dstRowStride =
         _mesa_image_row_stride(&ctx->Pack, width, format, type);
      GLubyte *src;
      GLint srcRowStride;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT, &src, &srcRowStride);

      if (src) {
         if (bytesPerRow == dstRowStride && bytesPerRow == srcRowStride) {
            memcpy(dst, src, bytesPerRow * texImage->Height);
         }
         else {
            GLuint row;
            for (row = 0; row < height; row++) {
               memcpy(dst, src, bytesPerRow);
               dst += dstRowStride;
               src += srcRowStride;
            }
         }

         /* unmap src texture buffer */
         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset);
      }
      else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
      }
   }

   return memCopy;
}


/**
 * This is the software fallback for Driver.GetTexSubImage().
 * All error checking will have been done before this routine is called.
 * We'll call ctx->Driver.MapTextureImage() to access the data, then
 * unmap with ctx->Driver.UnmapTextureImage().
 */
void
_mesa_GetTexSubImage_sw(struct gl_context *ctx,
                        GLint xoffset, GLint yoffset, GLint zoffset,
                        GLsizei width, GLsizei height, GLint depth,
                        GLenum format, GLenum type, GLvoid *pixels,
                        struct gl_texture_image *texImage)
{
   const GLuint dimensions =
      _mesa_get_texture_dimensions(texImage->TexObject->Target);

   /* map dest buffer, if PBO */
   if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      /* Packing texture image into a PBO.
       * Map the (potentially) VRAM-based buffer into our process space so
       * we can write into it with the code below.
       * A hardware driver might use a sophisticated blit to move the
       * texture data to the PBO if the PBO is in VRAM along with the texture.
       */
      GLubyte *buf = (GLubyte *)
         ctx->Driver.MapBufferRange(ctx, 0, ctx->Pack.BufferObj->Size,
				    GL_MAP_WRITE_BIT, ctx->Pack.BufferObj,
                                    MAP_INTERNAL);
      if (!buf) {
         /* out of memory or other unexpected error */
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage(map PBO failed)");
         return;
      }
      /* <pixels> was an offset into the PBO.
       * Now make it a real, client-side pointer inside the mapped region.
       */
      pixels = ADD_POINTERS(buf, pixels);
   }

   if (get_tex_memcpy(ctx, xoffset, yoffset, zoffset, width, height, depth,
                      format, type, pixels, texImage)) {
      /* all done */
   }
   else if (format == GL_DEPTH_COMPONENT) {
      get_tex_depth(ctx, dimensions, xoffset, yoffset, zoffset,
                    width, height, depth, format, type, pixels, texImage);
   }
   else if (format == GL_DEPTH_STENCIL_EXT) {
      get_tex_depth_stencil(ctx, dimensions, xoffset, yoffset, zoffset,
                            width, height, depth, format, type, pixels,
                            texImage);
   }
   else if (format == GL_STENCIL_INDEX) {
      get_tex_stencil(ctx, dimensions, xoffset, yoffset, zoffset,
                      width, height, depth, format, type, pixels, texImage);
   }
   else if (format == GL_YCBCR_MESA) {
      get_tex_ycbcr(ctx, dimensions, xoffset, yoffset, zoffset,
                    width, height, depth, format, type, pixels, texImage);
   }
   else {
      get_tex_rgba(ctx, dimensions, xoffset, yoffset, zoffset,
                   width, height, depth, format, type, pixels, texImage);
   }

   if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      ctx->Driver.UnmapBuffer(ctx, ctx->Pack.BufferObj, MAP_INTERNAL);
   }
}



/**
 * This is the software fallback for Driver.GetCompressedTexSubImage().
 * All error checking will have been done before this routine is called.
 */
void
_mesa_GetCompressedTexSubImage_sw(struct gl_context *ctx,
                                  struct gl_texture_image *texImage,
                                  GLint xoffset, GLint yoffset,
                                  GLint zoffset, GLsizei width,
                                  GLint height, GLint depth,
                                  GLvoid *img)
{
   const GLuint dimensions =
      _mesa_get_texture_dimensions(texImage->TexObject->Target);
   struct compressed_pixelstore store;
   GLint slice;
   GLubyte *dest;

   _mesa_compute_compressed_pixelstore(dimensions, texImage->TexFormat,
                                       width, height, depth,
                                       &ctx->Pack, &store);

   if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      /* pack texture image into a PBO */
      dest = (GLubyte *)
         ctx->Driver.MapBufferRange(ctx, 0, ctx->Pack.BufferObj->Size,
				    GL_MAP_WRITE_BIT, ctx->Pack.BufferObj,
                                    MAP_INTERNAL);
      if (!dest) {
         /* out of memory or other unexpected error */
         _mesa_error(ctx, GL_OUT_OF_MEMORY,
                     "glGetCompresssedTexImage(map PBO failed)");
         return;
      }
      dest = ADD_POINTERS(dest, img);
   } else {
      dest = img;
   }

   dest += store.SkipBytes;

   for (slice = 0; slice < store.CopySlices; slice++) {
      GLint srcRowStride;
      GLubyte *src;

      /* map src texture buffer */
      ctx->Driver.MapTextureImage(ctx, texImage, zoffset + slice,
                                  xoffset, yoffset, width, height,
                                  GL_MAP_READ_BIT, &src, &srcRowStride);

      if (src) {
         GLint i;
         for (i = 0; i < store.CopyRowsPerSlice; i++) {
            memcpy(dest, src, store.CopyBytesPerRow);
            dest += store.TotalBytesPerRow;
            src += srcRowStride;
         }

         ctx->Driver.UnmapTextureImage(ctx, texImage, zoffset + slice);

         /* Advance to next slice */
         dest += store.TotalBytesPerRow * (store.TotalRowsPerSlice - store.CopyRowsPerSlice);

      } else {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetCompresssedTexImage");
      }
   }

   if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      ctx->Driver.UnmapBuffer(ctx, ctx->Pack.BufferObj, MAP_INTERNAL);
   }
}


/**
 * Validate the texture target enum supplied to glGetTex(ture)Image or
 * glGetCompressedTex(ture)Image.
 */
static GLboolean
legal_getteximage_target(struct gl_context *ctx, GLenum target, bool dsa)
{
   switch (target) {
   case GL_TEXTURE_1D:
   case GL_TEXTURE_2D:
   case GL_TEXTURE_3D:
      return GL_TRUE;
   case GL_TEXTURE_RECTANGLE_NV:
      return ctx->Extensions.NV_texture_rectangle;
   case GL_TEXTURE_1D_ARRAY_EXT:
   case GL_TEXTURE_2D_ARRAY_EXT:
      return ctx->Extensions.EXT_texture_array;
   case GL_TEXTURE_CUBE_MAP_ARRAY:
      return ctx->Extensions.ARB_texture_cube_map_array;

   /* Section 8.11 (Texture Queries) of the OpenGL 4.5 core profile spec
    * (30.10.2014) says:
    *    "An INVALID_ENUM error is generated if the effective target is not
    *    one of TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_1D_ARRAY,
    *    TEXTURE_2D_ARRAY, TEXTURE_CUBE_MAP_ARRAY, TEXTURE_RECTANGLE, one of
    *    the targets from table 8.19 (for GetTexImage and GetnTexImage *only*),
    *    or TEXTURE_CUBE_MAP (for GetTextureImage *only*)." (Emphasis added.)
    */
   case GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB:
   case GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB:
   case GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB:
   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB:
   case GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB:
   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB:
      return dsa ? GL_FALSE : ctx->Extensions.ARB_texture_cube_map;
   case GL_TEXTURE_CUBE_MAP:
      return dsa ? GL_TRUE : GL_FALSE;
   default:
      return GL_FALSE;
   }
}


/**
 * Do error checking for a glGetTex(ture)Image() call.
 * \return GL_TRUE if any error, GL_FALSE if no errors.
 */
static GLboolean
getteximage_error_check(struct gl_context *ctx,
                        struct gl_texture_image *texImage,
                        GLenum target, GLint level,
                        GLenum format, GLenum type, GLsizei clientMemSize,
                        GLvoid *pixels, bool dsa)
{
   const GLint maxLevels = _mesa_max_texture_levels(ctx, target);
   const GLuint dimensions = (target == GL_TEXTURE_3D) ? 3 : 2;
   GLenum baseFormat;
   const char *suffix = dsa ? "ture" : "";

   assert(texImage);
   assert(maxLevels != 0);
   if (level < 0 || level >= maxLevels) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glGetTex%sImage(level out of range)", suffix);
      return GL_TRUE;
   }

   /*
    * Format and type checking has been moved up to GetnTexImage and
    * GetTextureImage so that it happens before getting the texImage object.
    */

   baseFormat = _mesa_get_format_base_format(texImage->TexFormat);

   /* Make sure the requested image format is compatible with the
    * texture's format.
    */
   if (_mesa_is_color_format(format)
       && !_mesa_is_color_format(baseFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetTex%sImage(format mismatch)", suffix);
      return GL_TRUE;
   }
   else if (_mesa_is_depth_format(format)
            && !_mesa_is_depth_format(baseFormat)
            && !_mesa_is_depthstencil_format(baseFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetTex%sImage(format mismatch)", suffix);
      return GL_TRUE;
   }
   else if (_mesa_is_stencil_format(format)
            && !ctx->Extensions.ARB_texture_stencil8) {
      _mesa_error(ctx, GL_INVALID_ENUM,
                  "glGetTex%sImage(format=GL_STENCIL_INDEX)", suffix);
      return GL_TRUE;
   }
   else if (_mesa_is_ycbcr_format(format)
            && !_mesa_is_ycbcr_format(baseFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetTex%sImage(format mismatch)", suffix);
      return GL_TRUE;
   }
   else if (_mesa_is_depthstencil_format(format)
            && !_mesa_is_depthstencil_format(baseFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetTex%sImage(format mismatch)", suffix);
      return GL_TRUE;
   }
   else if (!_mesa_is_stencil_format(format) && _mesa_is_enum_format_integer(format) !=
            _mesa_is_format_integer(texImage->TexFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetTex%sImage(format mismatch)", suffix);
      return GL_TRUE;
   }

   if (!_mesa_validate_pbo_access(dimensions, &ctx->Pack, texImage->Width,
                                  texImage->Height, texImage->Depth,
                                  format, type, clientMemSize, pixels)) {
      if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetTex%sImage(out of bounds PBO access)", suffix);
      } else {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(out of bounds access:"
                     " bufSize (%d) is too small)",
                     dsa ? "glGetTextureImage" : "glGetnTexImageARB",
                     clientMemSize);
      }
      return GL_TRUE;
   }

   if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      /* PBO should not be mapped */
      if (_mesa_check_disallowed_mapping(ctx->Pack.BufferObj)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetTex%sImage(PBO is mapped)", suffix);
         return GL_TRUE;
      }
   }

   return GL_FALSE;
}


/**
 * This is the implementation for glGetnTexImageARB, glGetTextureImage,
 * and glGetTexImage.
 *
 * Requires caller to pass in texImage object because _mesa_GetTextureImage
 * must handle the GL_TEXTURE_CUBE_MAP target.
 *
 * \param target texture target.
 * \param level image level.
 * \param format pixel data format for returned image.
 * \param type pixel data type for returned image.
 * \param bufSize size of the pixels data buffer.
 * \param pixels returned pixel data.
 * \param dsa True when the caller is an ARB_direct_state_access function,
 *            false otherwise
 */
static void
get_texture_image(struct gl_context *ctx,
                  struct gl_texture_object *texObj,
                  struct gl_texture_image *texImage, GLenum target,
                  GLint level, GLenum format, GLenum type,
                  GLsizei bufSize, GLvoid *pixels, bool dsa)
{
   assert(texObj);
   assert(texImage);

   FLUSH_VERTICES(ctx, 0);

   /*
    * Legal target checking has been moved up to GetnTexImage and
    * GetTextureImage so that it can be caught before receiving a NULL
    * texImage object and exiting.
    */

   if (getteximage_error_check(ctx, texImage, target, level, format,
                               type, bufSize, pixels, dsa)) {
      return;
   }

   if (!_mesa_is_bufferobj(ctx->Pack.BufferObj) && !pixels) {
      /* not an error, do nothing */
      return;
   }

   if (_mesa_is_zero_size_texture(texImage))
      return;

   if (MESA_VERBOSE & (VERBOSE_API | VERBOSE_TEXTURE)) {
      _mesa_debug(ctx, "glGetTex%sImage(tex %u) format = %s, w=%d, h=%d,"
                  " dstFmt=0x%x, dstType=0x%x\n",
                  dsa ? "ture": "",
                  texObj->Name,
                  _mesa_get_format_name(texImage->TexFormat),
                  texImage->Width, texImage->Height,
                  format, type);
   }

   _mesa_lock_texture(ctx, texObj);
   {
      ctx->Driver.GetTexSubImage(ctx, 0, 0, 0,
                                 texImage->Width, texImage->Height,
                                 texImage->Depth,
                                 format, type, pixels, texImage);
   }
   _mesa_unlock_texture(ctx, texObj);
}

/**
 * Get texture image.  Called by glGetTexImage.
 *
 * \param target texture target.
 * \param level image level.
 * \param format pixel data format for returned image.
 * \param type pixel data type for returned image.
 * \param bufSize size of the pixels data buffer.
 * \param pixels returned pixel data.
 */
void GLAPIENTRY
_mesa_GetnTexImageARB(GLenum target, GLint level, GLenum format,
                      GLenum type, GLsizei bufSize, GLvoid *pixels)
{
   struct gl_texture_object *texObj;
   struct gl_texture_image *texImage;
   GLenum err;
   GET_CURRENT_CONTEXT(ctx);

   /*
    * This has been moved here because a format/type mismatch can cause a NULL
    * texImage object, which in turn causes the mismatch error to be
    * ignored.
    */
   err = _mesa_error_check_format_and_type(ctx, format, type);
   if (err != GL_NO_ERROR) {
      _mesa_error(ctx, err, "glGetnTexImage(format/type)");
      return;
   }

   /*
    * Legal target checking has been moved here to prevent exiting with a NULL
    * texImage object.
    */
   if (!legal_getteximage_target(ctx, target, false)) {
      _mesa_error(ctx, GL_INVALID_ENUM, "glGetnTexImage(target=0x%x)",
                  target);
      return;
   }

   texObj = _mesa_get_current_tex_object(ctx, target);
   if (!texObj)
      return;

   texImage = _mesa_select_tex_image(texObj, target, level);
   if (!texImage)
      return;

   get_texture_image(ctx, texObj, texImage, target, level, format, type,
                     bufSize, pixels, false);
}


void GLAPIENTRY
_mesa_GetTexImage( GLenum target, GLint level, GLenum format,
                   GLenum type, GLvoid *pixels )
{
   _mesa_GetnTexImageARB(target, level, format, type, INT_MAX, pixels);
}

/**
 * Get texture image.
 *
 * \param texture texture name.
 * \param level image level.
 * \param format pixel data format for returned image.
 * \param type pixel data type for returned image.
 * \param bufSize size of the pixels data buffer.
 * \param pixels returned pixel data.
 */
void GLAPIENTRY
_mesa_GetTextureImage(GLuint texture, GLint level, GLenum format,
                      GLenum type, GLsizei bufSize, GLvoid *pixels)
{
   struct gl_texture_object *texObj;
   struct gl_texture_image *texImage;
   int i;
   GLint image_stride;
   GLenum err;
   GET_CURRENT_CONTEXT(ctx);

   /*
    * This has been moved here because a format/type mismatch can cause a NULL
    * texImage object, which in turn causes the mismatch error to be
    * ignored.
    */
   err = _mesa_error_check_format_and_type(ctx, format, type);
   if (err != GL_NO_ERROR) {
      _mesa_error(ctx, err, "glGetTextureImage(format/type)");
      return;
   }

   texObj = _mesa_lookup_texture_err(ctx, texture, "glGetTextureImage");
   if (!texObj)
      return;

   /*
    * Legal target checking has been moved here to prevent exiting with a NULL
    * texImage object.
    */
   if (!legal_getteximage_target(ctx, texObj->Target, true)) {
      _mesa_error(ctx, GL_INVALID_ENUM, "glGetTextureImage(target=%s)",
                  _mesa_enum_to_string(texObj->Target));
      return;
   }

   /* Must handle special case GL_TEXTURE_CUBE_MAP. */
   if (texObj->Target == GL_TEXTURE_CUBE_MAP) {

      /* Make sure the texture object is a proper cube.
       * (See texturesubimage in teximage.c for details on why this check is
       * performed.)
       */
      if (!_mesa_cube_level_complete(texObj, level)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetTextureImage(cube map incomplete)");
         return;
      }

      /* Copy each face. */
      for (i = 0; i < 6; ++i) {
         texImage = texObj->Image[i][level];
         assert(texImage);

         get_texture_image(ctx, texObj, texImage, texObj->Target, level,
                           format, type, bufSize, pixels, true);

         image_stride = _mesa_image_image_stride(&ctx->Pack, texImage->Width,
                                                 texImage->Height, format,
                                                 type);
         pixels = (GLubyte *) pixels + image_stride;
         bufSize -= image_stride;
      }
   }
   else {
      texImage = _mesa_select_tex_image(texObj, texObj->Target, level);
      if (!texImage)
         return;

      get_texture_image(ctx, texObj, texImage, texObj->Target, level,
                        format, type, bufSize, pixels, true);
   }
}

/**
 * Do error checking for a glGetCompressedTexImage() call.
 * \return GL_TRUE if any error, GL_FALSE if no errors.
 */
static GLboolean
getcompressedteximage_error_check(struct gl_context *ctx,
                                  struct gl_texture_image *texImage,
                                  GLenum target,
                                  GLint level, GLsizei clientMemSize,
                                  GLvoid *img, bool dsa)
{
   const GLint maxLevels = _mesa_max_texture_levels(ctx, target);
   GLuint compressedSize, dimensions;
   const char *suffix = dsa ? "ture" : "";

   assert(texImage);

   if (!legal_getteximage_target(ctx, target, dsa)) {
      _mesa_error(ctx, GL_INVALID_ENUM,
                  "glGetCompressedTex%sImage(target=%s)", suffix,
                  _mesa_enum_to_string(target));
      return GL_TRUE;
   }

   assert(maxLevels != 0);
   if (level < 0 || level >= maxLevels) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glGetCompressedTex%sImage(bad level = %d)", suffix, level);
      return GL_TRUE;
   }

   if (!_mesa_is_format_compressed(texImage->TexFormat)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glGetCompressedTex%sImage(texture is not compressed)",
                  suffix);
      return GL_TRUE;
   }

   compressedSize = _mesa_format_image_size(texImage->TexFormat,
                                            texImage->Width,
                                            texImage->Height,
                                            texImage->Depth);

   /* Check for invalid pixel storage modes */
   dimensions = _mesa_get_texture_dimensions(texImage->TexObject->Target);
   if (!_mesa_compressed_pixel_storage_error_check(ctx, dimensions,
                                              &ctx->Pack, dsa ?
                                              "glGetCompressedTextureImage":
                                              "glGetCompressedTexImage")) {
      return GL_TRUE;
   }

   if (!_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
      /* do bounds checking on writing to client memory */
      if (clientMemSize < (GLsizei) compressedSize) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(out of bounds access: bufSize (%d) is too small)",
                     dsa ? "glGetCompressedTextureImage" :
                     "glGetnCompressedTexImageARB", clientMemSize);
         return GL_TRUE;
      }
   } else {
      /* do bounds checking on PBO write */
      if ((const GLubyte *) img + compressedSize >
          (const GLubyte *) ctx->Pack.BufferObj->Size) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetCompressedTex%sImage(out of bounds PBO access)",
                     suffix);
         return GL_TRUE;
      }

      /* make sure PBO is not mapped */
      if (_mesa_check_disallowed_mapping(ctx->Pack.BufferObj)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetCompressedTex%sImage(PBO is mapped)", suffix);
         return GL_TRUE;
      }
   }

   return GL_FALSE;
}

/** Implements glGetnCompressedTexImageARB, glGetCompressedTexImage, and
 * glGetCompressedTextureImage.
 *
 * texImage must be passed in because glGetCompressedTexImage must handle the
 * target GL_TEXTURE_CUBE_MAP.
 */
void
_mesa_get_compressed_texture_image(struct gl_context *ctx,
                                   struct gl_texture_object *texObj,
                                   struct gl_texture_image *texImage,
                                   GLenum target, GLint level,
                                   GLsizei bufSize, GLvoid *pixels,
                                   bool dsa)
{
   assert(texObj);
   assert(texImage);

   FLUSH_VERTICES(ctx, 0);

   if (getcompressedteximage_error_check(ctx, texImage, target, level,
                                         bufSize, pixels, dsa)) {
      return;
   }

   if (!_mesa_is_bufferobj(ctx->Pack.BufferObj) && !pixels) {
      /* not an error, do nothing */
      return;
   }

   if (_mesa_is_zero_size_texture(texImage))
      return;

   if (MESA_VERBOSE & (VERBOSE_API | VERBOSE_TEXTURE)) {
      _mesa_debug(ctx,
                  "glGetCompressedTex%sImage(tex %u) format = %s, w=%d, h=%d\n",
                  dsa ? "ture" : "", texObj->Name,
                  _mesa_get_format_name(texImage->TexFormat),
                  texImage->Width, texImage->Height);
   }

   _mesa_lock_texture(ctx, texObj);
   {
      ctx->Driver.GetCompressedTexSubImage(ctx, texImage,
                                           0, 0, 0,
                                           texImage->Width, texImage->Height,
                                           texImage->Depth, pixels);
   }
   _mesa_unlock_texture(ctx, texObj);
}

void GLAPIENTRY
_mesa_GetnCompressedTexImageARB(GLenum target, GLint level, GLsizei bufSize,
                                GLvoid *img)
{
   struct gl_texture_object *texObj;
   struct gl_texture_image *texImage;
   GET_CURRENT_CONTEXT(ctx);

   texObj = _mesa_get_current_tex_object(ctx, target);
   if (!texObj)
      return;

   texImage = _mesa_select_tex_image(texObj, target, level);
   if (!texImage)
      return;

   _mesa_get_compressed_texture_image(ctx, texObj, texImage, target, level,
                                      bufSize, img, false);
}

void GLAPIENTRY
_mesa_GetCompressedTexImage(GLenum target, GLint level, GLvoid *img)
{
   _mesa_GetnCompressedTexImageARB(target, level, INT_MAX, img);
}

/**
 * Get compressed texture image.
 *
 * \param texture texture name.
 * \param level image level.
 * \param bufSize size of the pixels data buffer.
 * \param pixels returned pixel data.
 */
void GLAPIENTRY
_mesa_GetCompressedTextureImage(GLuint texture, GLint level,
                                GLsizei bufSize, GLvoid *pixels)
{
   struct gl_texture_object *texObj;
   struct gl_texture_image *texImage;
   int i;
   GLint image_stride;
   GET_CURRENT_CONTEXT(ctx);

   texObj = _mesa_lookup_texture_err(ctx, texture,
                                     "glGetCompressedTextureImage");
   if (!texObj)
      return;

   /* Must handle special case GL_TEXTURE_CUBE_MAP. */
   if (texObj->Target == GL_TEXTURE_CUBE_MAP) {

      /* Make sure the texture object is a proper cube.
       * (See texturesubimage in teximage.c for details on why this check is
       * performed.)
       */
      if (!_mesa_cube_level_complete(texObj, level)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glGetCompressedTextureImage(cube map incomplete)");
         return;
      }

      /* Copy each face. */
      for (i = 0; i < 6; ++i) {
         texImage = texObj->Image[i][level];
         assert(texImage);

         _mesa_get_compressed_texture_image(ctx, texObj, texImage,
                                            texObj->Target, level,
                                            bufSize, pixels, true);

         /* Compressed images don't have a client format */
         image_stride = _mesa_format_image_size(texImage->TexFormat,
                                                texImage->Width,
                                                texImage->Height, 1);

         pixels = (GLubyte *) pixels + image_stride;
         bufSize -= image_stride;
      }
   }
   else {
      texImage = _mesa_select_tex_image(texObj, texObj->Target, level);
      if (!texImage)
         return;

      _mesa_get_compressed_texture_image(ctx, texObj, texImage,
                                         texObj->Target, level, bufSize,
                                         pixels, true);
   }
}