pngread.c

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         png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_sBIT_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
         png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_sRGB_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
         png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_iCCP_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
         png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_sPLT_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
         png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_tEXt_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
         png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_tIME_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
         png_handle_tIME(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_tRNS_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
         png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_zTXt_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
         png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#if defined(PNG_READ_iTXt_SUPPORTED)
      else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
         png_handle_iTXt(png_ptr, info_ptr, length);
#endif
      else
         png_handle_unknown(png_ptr, info_ptr, length);
   }
}

/* optional call to update the users info_ptr structure */
void PNGAPI
png_read_update_info(png_structp png_ptr, png_infop info_ptr)
{
   png_debug(1, "in png_read_update_info\n");
   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
      png_read_start_row(png_ptr);
   else
      png_warning(png_ptr,
      "Ignoring extra png_read_update_info() call; row buffer not reallocated");
   png_read_transform_info(png_ptr, info_ptr);
}

/* Initialize palette, background, etc, after transformations
 * are set, but before any reading takes place.  This allows
 * the user to obtain a gamma-corrected palette, for example.
 * If the user doesn't call this, we will do it ourselves.
 */
void PNGAPI
png_start_read_image(png_structp png_ptr)
{
   png_debug(1, "in png_start_read_image\n");
   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
      png_read_start_row(png_ptr);
}

void PNGAPI
png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
{
#ifdef PNG_USE_LOCAL_ARRAYS
   PNG_IDAT;
   const int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
   const int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
#endif
   int ret;
   png_debug2(1, "in png_read_row (row %lu, pass %d)\n",
      png_ptr->row_number, png_ptr->pass);
   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
      png_read_start_row(png_ptr);

#if defined(PNG_READ_INTERLACING_SUPPORTED)
   /* if interlaced and we do not need a new row, combine row and return */
   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
   {
      switch (png_ptr->pass)
      {
         case 0:
            if (png_ptr->row_number & 0x07)
            {
               if (dsp_row != NULL)
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 1:
            if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
            {
               if (dsp_row != NULL)
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 2:
            if ((png_ptr->row_number & 0x07) != 4)
            {
               if (dsp_row != NULL && (png_ptr->row_number & 4))
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 3:
            if ((png_ptr->row_number & 3) || png_ptr->width < 3)
            {
               if (dsp_row != NULL)
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 4:
            if ((png_ptr->row_number & 3) != 2)
            {
               if (dsp_row != NULL && (png_ptr->row_number & 2))
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 5:
            if ((png_ptr->row_number & 1) || png_ptr->width < 2)
            {
               if (dsp_row != NULL)
                  png_combine_row(png_ptr, dsp_row,
                     png_pass_dsp_mask[png_ptr->pass]);
               png_read_finish_row(png_ptr);
               return;
            }
            break;
         case 6:
            if (!(png_ptr->row_number & 1))
            {
               png_read_finish_row(png_ptr);
               return;
            }
            break;
      }
   }
#endif

   if (!(png_ptr->mode & PNG_HAVE_IDAT))
      png_error(png_ptr, "Invalid attempt to read row data");

   png_ptr->zstream.next_out = png_ptr->row_buf;
   png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
   do
   {
      if (!(png_ptr->zstream.avail_in))
      {
         while (!png_ptr->idat_size)
         {
         	// kumar: idat_size = 0, get next IDAT
            png_byte chunk_length[4];

            png_crc_finish(png_ptr, 0);

            png_read_data(png_ptr, chunk_length, 4);
            png_ptr->idat_size = png_get_uint_32(chunk_length);

            if (png_ptr->idat_size > PNG_MAX_UINT)
              png_error(png_ptr, "Invalid chunk length.");

            png_reset_crc(png_ptr);
            png_crc_read(png_ptr, png_ptr->chunk_name, 4);
            if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
               png_error(png_ptr, "Not enough image data");
         }
         png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
         png_ptr->zstream.next_in = png_ptr->zbuf;
         if (png_ptr->zbuf_size > png_ptr->idat_size)
            png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
         png_crc_read(png_ptr, png_ptr->zbuf,
            (png_size_t)png_ptr->zstream.avail_in);
         png_ptr->idat_size -= png_ptr->zstream.avail_in;
      }
      
      // kumar: decode one row of the pass or decode the whole image ??
      // total in, total out = irowbytes
      ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
      if (ret == Z_STREAM_END)
      {
         if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
            png_ptr->idat_size)
            png_error(png_ptr, "Extra compressed data");
         png_ptr->mode |= PNG_AFTER_IDAT;
         png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
         break;
      }
      if (ret != Z_OK)
         png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
                   "Decompression error");

   } while (png_ptr->zstream.avail_out);

   png_ptr->row_info.color_type = png_ptr->color_type;
   png_ptr->row_info.width = png_ptr->iwidth;
   png_ptr->row_info.channels = png_ptr->channels;
   png_ptr->row_info.bit_depth = png_ptr->bit_depth;
   png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
   png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
      (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
   
	// kumar: png_ptr->row_buf[0] is the filter type byte
   if(png_ptr->row_buf[0])
   	png_read_filter_row(png_ptr, &(png_ptr->row_info),
      	png_ptr->row_buf + 1, png_ptr->prev_row + 1,
      	(int)(png_ptr->row_buf[0]));
   
	// kumar: copy row_buf to prev_row
   png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
      png_ptr->rowbytes + 1);
   
#if defined(PNG_MNG_FEATURES_SUPPORTED)
   if((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
      (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
   {
      /* Intrapixel differencing */
      png_do_read_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
   }
#endif
	// kumar: output the result according to the previous tranformation settings.
   if (png_ptr->transformations)
      png_do_read_transformations(png_ptr);

#if defined(PNG_READ_INTERLACING_SUPPORTED)
   /* blow up interlaced rows to full size */
   if (png_ptr->interlaced &&
      (png_ptr->transformations & PNG_INTERLACE))
   {
      if (png_ptr->pass < 6)
/*       old interface (pre-1.0.9):
         png_do_read_interlace(&(png_ptr->row_info),
            png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 */
         png_do_read_interlace(png_ptr);

      //if (dsp_row != NULL)
         //png_combine_row(png_ptr, dsp_row,
           // png_pass_dsp_mask[png_ptr->pass]);
      // row is the output buffer
      //if (row != NULL)
         png_combine_row(png_ptr, row,
            png_pass_mask[png_ptr->pass]);
   }
   else
#endif
   {	//output from row_buf to the destination buffer
      //if (row != NULL)
         png_combine_row(png_ptr, row, 0xff);
      //if (dsp_row != NULL)
        // png_combine_row(png_ptr, dsp_row, 0xff);
   }
   png_read_finish_row(png_ptr);

   if (png_ptr->read_row_fn != NULL)
      (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}

/* Read one or more rows of image data.  If the image is interlaced,
 * and png_set_interlace_handling() has been called, the rows need to
 * contain the contents of the rows from the previous pass.  If the
 * image has alpha or transparency, and png_handle_alpha()[*] has been
 * called, the rows contents must be initialized to the contents of the
 * screen.
 *
 * "row" holds the actual image, and pixels are placed in it
 * as they arrive.  If the image is displayed after each pass, it will
 * appear to "sparkle" in.  "display_row" can be used to display a
 * "chunky" progressive image, with finer detail added as it becomes
 * available.  If you do not want this "chunky" display, you may pass
 * NULL for display_row.  If you do not want the sparkle display, and
 * you have not called png_handle_alpha(), you may pass NULL for rows.
 * If you have called png_handle_alpha(), and the image has either an
 * alpha channel or a transparency chunk, you must provide a buffer for
 * rows.  In this case, you do not have to provide a display_row buffer
 * also, but you may.  If the image is not interlaced, or if you have
 * not called png_set_interlace_handling(), the display_row buffer will
 * be ignored, so pass NULL to it.
 *
 * [*] png_handle_alpha() does not exist yet, as of libpng version 1.2.5
 */

void PNGAPI
png_read_rows(png_structp png_ptr, png_bytepp row,
   png_bytepp display_row, png_uint_32 num_rows)
{
   png_uint_32 i;
   png_bytepp rp;
   png_bytepp dp;

   png_debug(1, "in png_read_rows\n");
   rp = row;
   dp = display_row;
   if (rp != NULL && dp != NULL)
      for (i = 0; i < num_rows; i++)
      {
         png_bytep rptr = *rp++;
         png_bytep dptr = *dp++;

         png_read_row(png_ptr, rptr, dptr);
      }
   else if(rp != NULL)
      for (i = 0; i < num_rows; i++)
      {
         png_bytep rptr = *rp;
         png_read_row(png_ptr, rptr, png_bytep_NULL);
         rp++;
      }
   else if(dp != NULL)
      for (i = 0; i < num_rows; i++)
      {
         png_bytep dptr = *dp;
         png_read_row(png_ptr, png_bytep_NULL, dptr);
         dp++;
      }
}

/* Read the entire image.  If the image has an alpha channel or a tRNS
 * chunk, and you have called png_handle_alpha()[*], you will need to
 * initialize the image to the current image that PNG will be overlaying.
 * We set the num_rows again here, in case it was incorrectly set in
 * png_read_start_row() by a call to png_read_update_info() or
 * png_start_read_image() if png_set_interlace_handling() wasn't called
 * prior to either of these functions like it should have been.  You can
 * only call this function once.  If you desire to have an image for
 * each pass of a interlaced image, use png_read_rows() instead.
 *
 * [*] png_handle_alpha() does not exist yet, as of libpng version 1.2.5
 */
void PNGAPI
png_read_image(volatile kal_bool *is_timeout, png_structp png_ptr, png_bytepp image)
{
   png_uint_32 i,image_height;
   int pass, j;
   png_bytepp rp;

   png_debug(1, "in png_read_image\n");

#ifdef PNG_READ_INTERLACING_SUPPORTED
   pass = png_set_interlace_handling(png_ptr);
#else
   if (png_ptr->interlaced)
      png_error(png_ptr,
        "Cannot read interlaced image -- interlace handler disabled.");
   pass = 1;
#endif


   image_height=png_ptr->height;
   png_ptr->num_rows = image_height; /* Make sure this is set correctly */

if (is_PNG_cliped)
{
 for (j = 0; j < pass; j++)
   for (i = 0; i < image_height; i++)
      {
      	if(*is_timeout)
      	 return;
       png_read_row(png_ptr, png_bytep_NULL, png_bytep_NULL);
      }
}
else
{
   for (j = 0; j < pass; j++)
   {
      rp = image;
      for (i = 0; i < image_height; i++)
      {
      	if(*is_timeout)
      	 return;
      	png_read_row(png_ptr, *rp, png_bytep_NULL);
	rp++;
      }
      }
   }
}

/* Read the end of the PNG file.  Will not read past the end of the
 * file, will verify the end is accurate, and will read any comments
 * or time information at the end of the file, if info is not NULL.
 */
void PNGAPI
png_read_end(png_structp png_ptr, png_infop info_ptr)
{
   png_byte chunk_length[4];
   png_uint_32 length;

   png_debug(1, "in png_read_end\n");
   png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */

   do
   {
#ifdef PNG_USE_LOCAL_ARRAYS
      PNG_IHDR;
      PNG_IDAT;
      PNG_IEND;
      PNG_PLTE;
#if defined(PNG_READ_bKGD_SUPPORTED)
      PNG_bKGD;
#endif
#if defined(PNG_READ_cHRM_SUPPORTED)
      PNG_cHRM;
#endif
#if defined(PNG_READ_gAMA_SUPPORTED)
      PNG_gAMA;
#endif
#if defined(PNG_READ_hIST_SUPPORTED)
      PNG_hIST;
#endif
#if defined(PNG_READ_iCCP_SUPPORTED)
      PNG_iCCP;
#endif
#if defined(PNG_READ_iTXt_SUPPORTED)
      PNG_iTXt;
#endif
#if defined(PNG_READ_oFFs_SUPPORTED)
      PNG_oFFs;
#endif
#if defined(PNG_READ_pCAL_SUPPORTED)
      PNG_pCAL;
#endif
#if defined(PNG_READ_pHYs_SUPPORTED)
      PNG_pHYs;
#endif
#if defined(PNG_READ_sBIT_SUPPORTED)
      PNG_sBIT;
#endif
#if defined(PNG_READ_sCAL_SUPPORTED)
      PNG_sCAL;
#endif
#if defined(PNG_READ_sPLT_SUPPORTED)
      PNG_sPLT;
#endif
#if defined(PNG_READ_sRGB_SUPPORTED)
      PNG_sRGB;
#endif
#if defined(PNG_READ_tEXt_SUPPORTED)
      PNG_tEXt;
#endif
#if defined(PNG_READ_tIME_SUPPORTED)
      PNG_tIME;
#endif
#if defined(PNG_READ_tRNS_SUPPORTED)
      PNG_tRNS;
#endif
#if defined(PNG_READ_zTXt_SUPPORTED)
      PNG_zTXt;
#endif
#endif /* PNG_GLOBAL_ARRAYS */

      png_read_data(png_ptr, chunk_length, 4);
      length = png_get_uint_32(chunk_length);

      png_reset_crc(png_ptr);