s_readpix.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

/*
 * Mesa 3-D graphics library
 * Version:  6.4
 *
 * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
 *
 * 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
 * BRIAN PAUL 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.
 */


#include "glheader.h"
#include "bufferobj.h"
#include "colormac.h"
#include "convolve.h"
#include "context.h"
#include "feedback.h"
#include "image.h"
#include "macros.h"
#include "imports.h"
#include "pixel.h"

#include "s_context.h"
#include "s_depth.h"
#include "s_span.h"
#include "s_stencil.h"



/*
 * Read a block of color index pixels.
 */
static void
read_index_pixels( GLcontext *ctx,
                   GLint x, GLint y,
                   GLsizei width, GLsizei height,
                   GLenum type, GLvoid *pixels,
                   const struct gl_pixelstore_attrib *packing )
{
   struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
   /*
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   */
   GLint i, readWidth;

   /* error checking */
   if (ctx->Visual.rgbMode) {
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels" );
      return;
   }

   if (type != GL_BYTE &&
       type != GL_UNSIGNED_BYTE &&
       type != GL_SHORT &&
       type != GL_UNSIGNED_SHORT &&
       type != GL_INT &&
       type != GL_UNSIGNED_INT &&
       type != GL_FLOAT) {
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels(index type)");
      return;
   }

   _swrast_use_read_buffer(ctx);

   /* XXX: width should never be > MAX_WIDTH since we did clipping earlier */
   readWidth = (width > MAX_WIDTH) ? MAX_WIDTH : width;

   /* process image row by row */
   for (i = 0; i < height; i++) {
      GLuint index[MAX_WIDTH];
      GLvoid *dest;
      ASSERT(rb->DataType == GL_UNSIGNED_INT);
      rb->GetRow(ctx, rb, readWidth, x, y + i, index);

      dest = _mesa_image_address2d(packing, pixels, width, height,
                                   GL_COLOR_INDEX, type, i, 0);

      _mesa_pack_index_span(ctx, readWidth, type, dest, index,
                            &ctx->Pack, ctx->_ImageTransferState);
   }

   _swrast_use_draw_buffer(ctx);
}



/**
 * Read pixels for format=GL_DEPTH_COMPONENT.
 */
static void
read_depth_pixels( GLcontext *ctx,
                   GLint x, GLint y,
                   GLsizei width, GLsizei height,
                   GLenum type, GLvoid *pixels,
                   const struct gl_pixelstore_attrib *packing )
{
   struct gl_renderbuffer *rb
      = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
   GLint readWidth;
   GLboolean bias_or_scale;

   /* Error checking */
   if (ctx->Visual.depthBits <= 0 || !rb) {
      /* No depth buffer */
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels" );
      return;
   }

   if (type != GL_BYTE &&
       type != GL_UNSIGNED_BYTE &&
       type != GL_SHORT &&
       type != GL_UNSIGNED_SHORT &&
       type != GL_INT &&
       type != GL_UNSIGNED_INT &&
       type != GL_FLOAT) {
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels(depth type)");
      return;
   }

   /* XXX: width should never be > MAX_WIDTH since we did clipping earlier */
   readWidth = (width > MAX_WIDTH) ? MAX_WIDTH : width;

   bias_or_scale = ctx->Pixel.DepthBias!=0.0 || ctx->Pixel.DepthScale!=1.0;

   if (type==GL_UNSIGNED_SHORT && ctx->Visual.depthBits == 16
       && !bias_or_scale && !packing->SwapBytes) {
      /* Special case: directly read 16-bit unsigned depth values. */
      GLint j;
      for (j=0;j<height;j++,y++) {
         GLdepth depth[MAX_WIDTH];
         GLushort *dst = (GLushort*) _mesa_image_address2d(packing, pixels,
                                width, height, GL_DEPTH_COMPONENT, type, j, 0);
         GLint i;
         _swrast_read_depth_span(ctx, rb, width, x, y, depth);
         for (i = 0; i < width; i++)
            dst[i] = depth[i];
      }
   }
   else if (type==GL_UNSIGNED_INT && ctx->Visual.depthBits == 32
            && !bias_or_scale && !packing->SwapBytes) {
      /* Special case: directly read 32-bit unsigned depth values. */
      GLint j;
      for (j=0;j<height;j++,y++) {
         GLdepth *dst = (GLdepth *) _mesa_image_address2d(packing, pixels,
                                width, height, GL_DEPTH_COMPONENT, type, j, 0);
         _swrast_read_depth_span(ctx, rb, width, x, y, dst);
      }
   }
   else {
      /* General case (slower) */
      GLint j;
      for (j=0;j<height;j++,y++) {
         GLfloat depth[MAX_WIDTH];
         GLvoid *dest;

         _swrast_read_depth_span_float(ctx, rb, readWidth, x, y, depth);

         dest = _mesa_image_address2d(packing, pixels, width, height,
                                      GL_DEPTH_COMPONENT, type, j, 0);

         _mesa_pack_depth_span(ctx, readWidth, (GLdepth *) dest, type,
                               depth, packing);
      }
   }
}


/**
 * Read pixels for format=GL_STENCIL_INDEX.
 */
static void
read_stencil_pixels( GLcontext *ctx,
                     GLint x, GLint y,
                     GLsizei width, GLsizei height,
                     GLenum type, GLvoid *pixels,
                     const struct gl_pixelstore_attrib *packing )
{
   struct gl_renderbuffer *rb
      = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
   GLint j, readWidth;

   if (type != GL_BYTE &&
       type != GL_UNSIGNED_BYTE &&
       type != GL_SHORT &&
       type != GL_UNSIGNED_SHORT &&
       type != GL_INT &&
       type != GL_UNSIGNED_INT &&
       type != GL_FLOAT &&
       type != GL_BITMAP) {
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels(stencil type)");
      return;
   }

   if (ctx->Visual.stencilBits <= 0 || !rb) {
      /* No stencil buffer */
      _mesa_error( ctx, GL_INVALID_OPERATION, "glReadPixels" );
      return;
   }

   /* XXX: width should never be > MAX_WIDTH since we did clipping earlier */
   readWidth = (width > MAX_WIDTH) ? MAX_WIDTH : width;

   /* process image row by row */
   for (j=0;j<height;j++,y++) {
      GLvoid *dest;
      GLstencil stencil[MAX_WIDTH];

      _swrast_read_stencil_span(ctx, rb, readWidth, x, y, stencil);

      dest = _mesa_image_address2d(packing, pixels, width, height,
                                   GL_STENCIL_INDEX, type, j, 0);

      _mesa_pack_stencil_span(ctx, readWidth, type, dest, stencil, packing);
   }
}



/**
 * Optimized glReadPixels for particular pixel formats:
 *   GL_UNSIGNED_BYTE, GL_RGBA
 * when pixel scaling, biasing and mapping are disabled.
 */
static GLboolean
read_fast_rgba_pixels( GLcontext *ctx,
                       GLint x, GLint y,
                       GLsizei width, GLsizei height,
                       GLenum format, GLenum type,
                       GLvoid *pixels,
                       const struct gl_pixelstore_attrib *packing )
{
   struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
   /* can't do scale, bias, mapping, etc */
   if (ctx->_ImageTransferState)
       return GL_FALSE;

   /* can't do fancy pixel packing */
   if (packing->Alignment != 1 || packing->SwapBytes || packing->LsbFirst)
      return GL_FALSE;

   {
      GLint srcX = x;
      GLint srcY = y;
      GLint readWidth = width;           /* actual width read */
      GLint readHeight = height;         /* actual height read */
      GLint skipPixels = packing->SkipPixels;
      GLint skipRows = packing->SkipRows;
      GLint rowLength;

      if (packing->RowLength > 0)
         rowLength = packing->RowLength;
      else
         rowLength = width;

      /*
       * Ready to read!
       * The window region at (destX, destY) of size (readWidth, readHeight)
       * will be read back.
       * We'll write pixel data to buffer pointed to by "pixels" but we'll
       * skip "skipRows" rows and skip "skipPixels" pixels/row.
       */
#if CHAN_BITS == 8
      if (format == GL_RGBA && type == GL_UNSIGNED_BYTE) {
#elif CHAN_BITS == 16
      if (format == GL_RGBA && type == GL_UNSIGNED_SHORT) {
#else
      if (0) {
#endif
         GLchan *dest = (GLchan *) pixels
                      + (skipRows * rowLength + skipPixels) * 4;
         GLint row;

         if (packing->Invert) {
            /* start at top and go down */
            dest += (readHeight - 1) * rowLength * 4;
            rowLength = -rowLength;
         }

         ASSERT(rb->GetRow);