pngrutil.c

Qt/Embedded是一个多平台的C++图形用户界面应用程序框架

/* pngrutil.c - utilities to read a PNG file
 *
 * libpng 1.0.7 - July 1, 2000
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This file contains routines that are only called from within
 * libpng itself during the course of reading an image.
 */

#define PNG_INTERNAL
#include "png.h"

#ifndef PNG_READ_BIG_ENDIAN_SUPPORTED
/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32 /* PRIVATE */
png_get_uint_32(png_bytep buf)
{
   png_uint_32 i = ((png_uint_32)(*buf) << 24) +
      ((png_uint_32)(*(buf + 1)) << 16) +
      ((png_uint_32)(*(buf + 2)) << 8) +
      (png_uint_32)(*(buf + 3));

   return (i);
}

#if defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_oFFs_SUPPORTED)
/* Grab a signed 32-bit integer from a buffer in big-endian format.  The
 * data is stored in the PNG file in two's complement format, and it is
 * assumed that the machine format for signed integers is the same. */
png_int_32 /* PRIVATE */
png_get_int_32(png_bytep buf)
{
   png_int_32 i = ((png_int_32)(*buf) << 24) +
      ((png_int_32)(*(buf + 1)) << 16) +
      ((png_int_32)(*(buf + 2)) << 8) +
      (png_int_32)(*(buf + 3));

   return (i);
}
#endif /* PNG_READ_pCAL_SUPPORTED */

/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16 /* PRIVATE */
png_get_uint_16(png_bytep buf)
{
   png_uint_16 i = (png_uint_16)(((png_uint_16)(*buf) << 8) +
      (png_uint_16)(*(buf + 1)));

   return (i);
}
#endif /* PNG_READ_BIG_ENDIAN_SUPPORTED */

/* Read data, and (optionally) run it through the CRC. */
void /* PRIVATE */
png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
{
   png_read_data(png_ptr, buf, length);
   png_calculate_crc(png_ptr, buf, length);
}

/* Optionally skip data and then check the CRC.  Depending on whether we
   are reading a ancillary or critical chunk, and how the program has set
   things up, we may calculate the CRC on the data and print a message.
   Returns '1' if there was a CRC error, '0' otherwise. */
int /* PRIVATE */
png_crc_finish(png_structp png_ptr, png_uint_32 skip)
{
   png_size_t i;
   png_size_t istop = png_ptr->zbuf_size;

   for (i = (png_size_t)skip; i > istop; i -= istop)
   {
      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
   }
   if (i)
   {
      png_crc_read(png_ptr, png_ptr->zbuf, i);
   }

   if (png_crc_error(png_ptr))
   {
      if (((png_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
           !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
          (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)))
      {
         png_chunk_warning(png_ptr, "CRC error");
      }
      else
      {
         png_chunk_error(png_ptr, "CRC error");
      }
      return (1);
   }

   return (0);
}

/* Compare the CRC stored in the PNG file with that calculated by libpng from
   the data it has read thus far. */
int /* PRIVATE */
png_crc_error(png_structp png_ptr)
{
   png_byte crc_bytes[4];
   png_uint_32 crc;
   int need_crc = 1;

   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
   {
      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
         need_crc = 0;
   }
   else                                                    /* critical */
   {
      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
         need_crc = 0;
   }

   png_read_data(png_ptr, crc_bytes, 4);

   if (need_crc)
   {
      crc = png_get_uint_32(crc_bytes);
      return ((int)(crc != png_ptr->crc));
   }
   else
      return (0);
}

#if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
    defined(PNG_READ_iCCP_SUPPORTED)
/*
 * Decompress trailing data in a chunk.  The assumption is that chunkdata
 * points at an allocated area holding the contents of a chunk with a
 * trailing compressed part.  What we get back is an allocated area
 * holding the original prefix part and an uncompressed version of the
 * trailing part (the malloc area passed in is freed).
 */
png_charp /* PRIVATE */
png_decompress_chunk(png_structp png_ptr, int comp_type,
                              png_charp chunkdata, png_size_t chunklength,
                              png_size_t prefix_size, png_size_t *newlength)
{
   static char msg[] = "Error decoding compressed text";
   png_charp text = NULL;
   png_size_t text_size;

   if (comp_type == PNG_TEXT_COMPRESSION_zTXt)
   {
      int ret = Z_OK;
      png_ptr->zstream.next_in = (png_bytep)(chunkdata + prefix_size);
      png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
      png_ptr->zstream.next_out = png_ptr->zbuf;
      png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

      text_size = 0;
      text = NULL;

      while (png_ptr->zstream.avail_in)
      {
         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
         if (ret != Z_OK && ret != Z_STREAM_END)
         {
            if (png_ptr->zstream.msg != NULL)
               png_warning(png_ptr, png_ptr->zstream.msg);
            else
               png_warning(png_ptr, msg);
            inflateReset(&png_ptr->zstream);
            png_ptr->zstream.avail_in = 0;

            if (text ==  NULL)
            {
               text_size = prefix_size + sizeof(msg) + 1;
               text = (png_charp)png_malloc(png_ptr, text_size);
               png_memcpy(text, chunkdata, prefix_size);
            }

            text[text_size - 1] = 0x00;

            /* Copy what we can of the error message into the text chunk */
            text_size = (png_size_t)(chunklength - (text - chunkdata) - 1);
            text_size = sizeof(msg) > text_size ? text_size : sizeof(msg);
            png_memcpy(text + prefix_size, msg, text_size + 1);
            break;
         }
         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
         {
            if (text == NULL)
            {
               text_size = prefix_size +
                   png_ptr->zbuf_size - png_ptr->zstream.avail_out;
               text = (png_charp)png_malloc(png_ptr, text_size + 1);
               png_memcpy(text + prefix_size, png_ptr->zbuf,
                          text_size - prefix_size);
               png_memcpy(text, chunkdata, prefix_size);
               *(text + text_size) = 0x00;
            }
            else
            {
               png_charp tmp;

               tmp = text;
               text = (png_charp)png_malloc(png_ptr, (png_uint_32)(text_size +
                  png_ptr->zbuf_size - png_ptr->zstream.avail_out + 1));
               png_memcpy(text, tmp, text_size);
               png_free(png_ptr, tmp);
               png_memcpy(text + text_size, png_ptr->zbuf,
                  (png_ptr->zbuf_size - png_ptr->zstream.avail_out));
               text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
               *(text + text_size) = 0x00;
            }
            if (ret == Z_STREAM_END)
               break;
            else
            {
               png_ptr->zstream.next_out = png_ptr->zbuf;
               png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
            }
         }
      }
      if (ret != Z_STREAM_END)
      {
#if !defined(PNG_NO_STDIO)
         char umsg[50];

         sprintf(umsg,"Incomplete compressed datastream in %s chunk",
             png_ptr->chunk_name);
         png_warning(png_ptr, umsg);
#else
         png_warning(png_ptr,
            "Incomplete compressed datastream in chunk other than IDAT");
#endif
      }

      inflateReset(&png_ptr->zstream);
      png_ptr->zstream.avail_in = 0;

      png_free(png_ptr, chunkdata);
      chunkdata = text;
      *newlength=text_size;
   }
   else /* if (comp_type != PNG_TEXT_COMPRESSION_zTXt) */
   {
#if !defined(PNG_NO_STDIO)
      char umsg[50];

      sprintf(umsg, "Unknown zTXt compression type %d", comp_type);
      png_warning(png_ptr, umsg);
#else
      png_warning(png_ptr, "Unknown zTXt compression type");
#endif

      /* Copy what we can of the error message into the text chunk */
      text_size = (png_size_t)(chunklength - (text - chunkdata));
      text_size = sizeof(msg) > text_size ? text_size : sizeof(msg);
      png_memcpy(text, msg, text_size);
   }

   return chunkdata;
}
#endif

/* read and check the IDHR chunk */
void /* PRIVATE */
png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_byte buf[13];
   png_uint_32 width, height;
   int bit_depth, color_type, compression_type, filter_type;
   int interlace_type;

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

   if (png_ptr->mode & PNG_HAVE_IHDR)
      png_error(png_ptr, "Out of place IHDR");

   /* check the length */
   if (length != 13)
      png_error(png_ptr, "Invalid IHDR chunk");

   png_ptr->mode |= PNG_HAVE_IHDR;

   png_crc_read(png_ptr, buf, 13);
   png_crc_finish(png_ptr, 0);

   width = png_get_uint_32(buf);
   height = png_get_uint_32(buf + 4);
   bit_depth = buf[8];
   color_type = buf[9];
   compression_type = buf[10];
   filter_type = buf[11];
   interlace_type = buf[12];

   /* check for width and height valid values */
   if (width == 0 || width > PNG_MAX_UINT || height == 0 ||
        height > PNG_MAX_UINT)
      png_error(png_ptr, "Invalid image size in IHDR");

   /* check other values */
   if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
      bit_depth != 8 && bit_depth != 16)
      png_error(png_ptr, "Invalid bit depth in IHDR");

   if (color_type < 0 || color_type == 1 ||
      color_type == 5 || color_type > 6)
      png_error(png_ptr, "Invalid color type in IHDR");

   if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
       ((color_type == PNG_COLOR_TYPE_RGB ||
         color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
         color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
      png_error(png_ptr, "Invalid color type/bit depth combination in IHDR");

   if (interlace_type >= PNG_INTERLACE_LAST)
      png_error(png_ptr, "Unknown interlace method in IHDR");

   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
      png_error(png_ptr, "Unknown compression method in IHDR");

   if (filter_type != PNG_FILTER_TYPE_BASE)
      png_error(png_ptr, "Unknown filter method in IHDR");

   /* set internal variables */
   png_ptr->width = width;
   png_ptr->height = height;
   png_ptr->bit_depth = (png_byte)bit_depth;
   png_ptr->interlaced = (png_byte)interlace_type;
   png_ptr->color_type = (png_byte)color_type;

   /* find number of channels */
   switch (png_ptr->color_type)
   {
      case PNG_COLOR_TYPE_GRAY:
      case PNG_COLOR_TYPE_PALETTE:
         png_ptr->channels = 1;
         break;
      case PNG_COLOR_TYPE_RGB:
         png_ptr->channels = 3;
         break;
      case PNG_COLOR_TYPE_GRAY_ALPHA:
         png_ptr->channels = 2;
         break;
      case PNG_COLOR_TYPE_RGB_ALPHA:
         png_ptr->channels = 4;
         break;
   }

   /* set up other useful info */
   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
   png_ptr->channels);
   png_ptr->rowbytes = ((png_ptr->width *
      (png_uint_32)png_ptr->pixel_depth + 7) >> 3);
   png_debug1(3,"bit_depth = %d\n", png_ptr->bit_depth);
   png_debug1(3,"channels = %d\n", png_ptr->channels);
   png_debug1(3,"rowbytes = %d\n", png_ptr->rowbytes);
   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
      color_type, interlace_type, compression_type, filter_type);
}

/* read and check the palette */
void /* PRIVATE */
png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_colorp palette;
   int num, i;
#ifndef PNG_NO_POINTER_INDEXING
   png_colorp pal_ptr;
#endif

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

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before PLTE");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid PLTE after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (png_ptr->mode & PNG_HAVE_PLTE)
      png_error(png_ptr, "Duplicate PLTE chunk");

   png_ptr->mode |= PNG_HAVE_PLTE;

#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
   if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
   {
      png_crc_finish(png_ptr, length);
      return;
   }
#endif

   if (length > 768 || length % 3)
   {
      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
      {
         png_warning(png_ptr, "Invalid palette chunk");
         png_crc_finish(png_ptr, length);
         return;
      }
      else
      {
         png_error(png_ptr, "Invalid palette chunk");
      }
   }

   num = (int)length / 3;

   palette = (png_colorp)png_zalloc(png_ptr, (uInt)num, sizeof (png_color));

#ifndef PNG_NO_POINTER_INDEXING
   for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
   {
      png_byte buf[3];

      png_crc_read(png_ptr, buf, 3);
      pal_ptr->red = buf[0];
      pal_ptr->green = buf[1];
      pal_ptr->blue = buf[2];
   }
#else
   for (i = 0; i < num; i++)
   {
      png_byte buf[3];

      png_crc_read(png_ptr, buf, 3);
      /* don't depend upon png_color being any order */
      palette[i].red = buf[0];
      palette[i].green = buf[1];
      palette[i].blue = buf[2];
   }
#endif

   /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
      whatever the normal CRC configuration tells us.  However, if we
      have an RGB image, the PLTE can be considered ancillary, so
      we will act as though it is. */
#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#endif
   {
      png_crc_finish(png_ptr, 0);
   }
#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
   {
      /* If we don't want to use the data from an ancillary chunk,
         we have two options: an error abort, or a warning and we