s_readpix.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/*
 * Mesa 3-D graphics library
 * Version:  7.0.3
 *
 * Copyright (C) 1999-2007  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 "state.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;
   GLint i;

   if (!rb)
      return;

   /* width should never be > MAX_WIDTH since we did clipping earlier */
   ASSERT(width <= MAX_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, width, x, y + i, index);

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

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



/**
 * 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_framebuffer *fb = ctx->ReadBuffer;
   struct gl_renderbuffer *rb = fb->_DepthBuffer;
   const GLboolean biasOrScale
      = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;

   if (!rb)
      return;

   /* clipping should have been done already */
   ASSERT(x >= 0);
   ASSERT(y >= 0);
   ASSERT(x + width <= (GLint) rb->Width);
   ASSERT(y + height <= (GLint) rb->Height);
   /* width should never be > MAX_WIDTH since we did clipping earlier */
   ASSERT(width <= MAX_WIDTH);

   if (type == GL_UNSIGNED_SHORT && fb->Visual.depthBits == 16
       && !biasOrScale && !packing->SwapBytes) {
      /* Special case: directly read 16-bit unsigned depth values. */
      GLint j;
      ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT16);
      ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
      for (j = 0; j < height; j++, y++) {
         void *dest =_mesa_image_address2d(packing, pixels, width, height,
                                           GL_DEPTH_COMPONENT, type, j, 0);
         rb->GetRow(ctx, rb, width, x, y, dest);
      }
   }
   else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 24
            && !biasOrScale && !packing->SwapBytes) {
      /* Special case: directly read 24-bit unsigned depth values. */
      GLint j;
      ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT24);
      ASSERT(rb->DataType == GL_UNSIGNED_INT);
      for (j = 0; j < height; j++, y++) {
         GLuint *dest = (GLuint *)
            _mesa_image_address2d(packing, pixels, width, height,
                                  GL_DEPTH_COMPONENT, type, j, 0);
         GLint k;
         rb->GetRow(ctx, rb, width, x, y, dest);
         /* convert range from 24-bit to 32-bit */
         for (k = 0; k < width; k++) {
            /* Note: put MSByte of 24-bit value into LSByte */
            dest[k] = (dest[k] << 8) | ((dest[k] >> 16) & 0xff);
         }
      }
   }
   else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 32
            && !biasOrScale && !packing->SwapBytes) {
      /* Special case: directly read 32-bit unsigned depth values. */
      GLint j;
      ASSERT(rb->InternalFormat == GL_DEPTH_COMPONENT32);
      ASSERT(rb->DataType == GL_UNSIGNED_INT);
      for (j = 0; j < height; j++, y++) {
         void *dest = _mesa_image_address2d(packing, pixels, width, height,
                                            GL_DEPTH_COMPONENT, type, j, 0);
         rb->GetRow(ctx, rb, width, x, y, dest);
      }
   }
   else {
      /* General case (slower) */
      GLint j;
      for (j = 0; j < height; j++, y++) {
         GLfloat depthValues[MAX_WIDTH];
         GLvoid *dest = _mesa_image_address2d(packing, pixels, width, height,
                                              GL_DEPTH_COMPONENT, type, j, 0);
         _swrast_read_depth_span_float(ctx, rb, width, x, y, depthValues);
         _mesa_pack_depth_span(ctx, width, dest, type, depthValues, 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_framebuffer *fb = ctx->ReadBuffer;
   struct gl_renderbuffer *rb = fb->_StencilBuffer;
   GLint j;

   if (!rb)
      return;

   /* width should never be > MAX_WIDTH since we did clipping earlier */
   ASSERT(width <= MAX_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, width, x, y, stencil);

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

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



/**
 * Optimized glReadPixels for particular pixel formats when pixel
 * scaling, biasing, mapping, etc. are disabled.
 * \return GL_TRUE if success, GL_FALSE if unable to do the readpixels
 */
static GLboolean
fast_read_rgba_pixels( GLcontext *ctx,
                       GLint x, GLint y,
                       GLsizei width, GLsizei height,
                       GLenum format, GLenum type,
                       GLvoid *pixels,
                       const struct gl_pixelstore_attrib *packing,
                       GLbitfield transferOps)
{
   struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;

   if (!rb)
      return GL_FALSE;

   ASSERT(rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB);

   /* clipping should have already been done */
   ASSERT(x + width <= (GLint) rb->Width);
   ASSERT(y + height <= (GLint) rb->Height);

   /* check for things we can't handle here */
   if (transferOps ||
       packing->SwapBytes ||
       packing->LsbFirst) {
      return GL_FALSE;
   }

   if (format == GL_RGBA && rb->DataType == type) {
      const GLint dstStride = _mesa_image_row_stride(packing, width,
                                                     format, type);
      GLubyte *dest
         = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
                                             format, type, 0, 0);
      GLint row;
      ASSERT(rb->GetRow);
      for (row = 0; row < height; row++) {
         rb->GetRow(ctx, rb, width, x, y + row, dest);
         dest += dstStride;
      }
      return GL_TRUE;
   }

   if (format == GL_RGB &&
       rb->DataType == GL_UNSIGNED_BYTE &&
       type == GL_UNSIGNED_BYTE) {
      const GLint dstStride = _mesa_image_row_stride(packing, width,
                                                     format, type);
      GLubyte *dest
         = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
                                             format, type, 0, 0);
      GLint row;
      ASSERT(rb->GetRow);
      for (row = 0; row < height; row++) {
         GLubyte tempRow[MAX_WIDTH][4];
         GLint col;
         rb->GetRow(ctx, rb, width, x, y + row, tempRow);
         /* convert RGBA to RGB */
         for (col = 0; col < width; col++) {
            dest[col * 3 + 0] = tempRow[col][0];
            dest[col * 3 + 1] = tempRow[col][1];
            dest[col * 3 + 2] = tempRow[col][2];
         }
         dest += dstStride;
      }
      return GL_TRUE;
   }

   /* not handled */
   return GL_FALSE;
}


/**
 * When we're using a low-precision color buffer (like 16-bit 5/6/5)
 * we have to adjust our color values a bit to pass conformance.
 * The problem is when a 5 or 6-bit color value is convert to an 8-bit
 * value and then a floating point value, the floating point values don't
 * increment uniformly as the 5 or 6-bit value is incremented.
 *
 * This function adjusts floating point values to compensate.
 */
static void
adjust_colors(GLcontext *ctx, GLuint n, GLfloat rgba[][4])
{
   const GLuint rShift = 8 - ctx->Visual.redBits;
   const GLuint gShift = 8 - ctx->Visual.greenBits;
   const GLuint bShift = 8 - ctx->Visual.blueBits;
   const GLfloat rScale = 1.0F / (GLfloat) ((1 << ctx->Visual.redBits  ) - 1);
   const GLfloat gScale = 1.0F / (GLfloat) ((1 << ctx->Visual.greenBits) - 1);
   const GLfloat bScale = 1.0F / (GLfloat) ((1 << ctx->Visual.blueBits ) - 1);
   GLuint i;
   for (i = 0; i < n; i++) {
      GLint r, g, b;
      /* convert float back to ubyte */
      CLAMPED_FLOAT_TO_UBYTE(r, rgba[i][RCOMP]);
      CLAMPED_FLOAT_TO_UBYTE(g, rgba[i][GCOMP]);
      CLAMPED_FLOAT_TO_UBYTE(b, rgba[i][BCOMP]);
      /* using only the N most significant bits of the ubyte value, convert to
       * float in [0,1].
       */
      rgba[i][RCOMP] = (GLfloat) (r >> rShift) * rScale;
      rgba[i][GCOMP] = (GLfloat) (g >> gShift) * gScale;
      rgba[i][BCOMP] = (GLfloat) (b >> bShift) * bScale;
   }
}