pngwutil.c

hl2 source code. Do not use it illegal.

/* pngwutil.c - utilities to write a PNG file
 *
 * libpng 1.0.3 - January 14, 1999
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
 * Copyright (c) 1996, 1997 Andreas Dilger
 * Copyright (c) 1998, 1999 Glenn Randers-Pehrson
 */

#define PNG_INTERNAL
#include "png.h"

/* Place a 32-bit number into a buffer in PNG byte order.  We work
 * with unsigned numbers for convenience, although one supported
 * ancillary chunk uses signed (two's complement) numbers.
 */
void
png_save_uint_32(png_bytep buf, png_uint_32 i)
{
   buf[0] = (png_byte)((i >> 24) & 0xff);
   buf[1] = (png_byte)((i >> 16) & 0xff);
   buf[2] = (png_byte)((i >> 8) & 0xff);
   buf[3] = (png_byte)(i & 0xff);
}

#if defined(PNG_WRITE_pCAL_SUPPORTED)
/* The png_save_int_32 function assumes integers are stored in two's
 * complement format.  If this isn't the case, then this routine needs to
 * be modified to write data in two's complement format.
 */
void
png_save_int_32(png_bytep buf, png_int_32 i)
{
   buf[0] = (png_byte)((i >> 24) & 0xff);
   buf[1] = (png_byte)((i >> 16) & 0xff);
   buf[2] = (png_byte)((i >> 8) & 0xff);
   buf[3] = (png_byte)(i & 0xff);
}
#endif

/* Place a 16-bit number into a buffer in PNG byte order.
 * The parameter is declared unsigned int, not png_uint_16,
 * just to avoid potential problems on pre-ANSI C compilers.
 */
void
png_save_uint_16(png_bytep buf, unsigned int i)
{
   buf[0] = (png_byte)((i >> 8) & 0xff);
   buf[1] = (png_byte)(i & 0xff);
}

/* Write a PNG chunk all at once.  The type is an array of ASCII characters
 * representing the chunk name.  The array must be at least 4 bytes in
 * length, and does not need to be null terminated.  To be safe, pass the
 * pre-defined chunk names here, and if you need a new one, define it
 * where the others are defined.  The length is the length of the data.
 * All the data must be present.  If that is not possible, use the
 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
 * functions instead.
 */
void
png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
   png_bytep data, png_size_t length)
{
   png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length);
   png_write_chunk_data(png_ptr, data, length);
   png_write_chunk_end(png_ptr);
}

/* Write the start of a PNG chunk.  The type is the chunk type.
 * The total_length is the sum of the lengths of all the data you will be
 * passing in png_write_chunk_data().
 */
void
png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
   png_uint_32 length)
{
   png_byte buf[4];
   png_debug2(0, "Writing %s chunk (%d bytes)\n", chunk_name, length);

   /* write the length */
   png_save_uint_32(buf, length);
   png_write_data(png_ptr, buf, (png_size_t)4);

   /* write the chunk name */
   png_write_data(png_ptr, chunk_name, (png_size_t)4);
   /* reset the crc and run it over the chunk name */
   png_reset_crc(png_ptr);
   png_calculate_crc(png_ptr, chunk_name, (png_size_t)4);
}

/* Write the data of a PNG chunk started with png_write_chunk_start().
 * Note that multiple calls to this function are allowed, and that the
 * sum of the lengths from these calls *must* add up to the total_length
 * given to png_write_chunk_start().
 */
void
png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   /* write the data, and run the CRC over it */
   if (data != NULL && length > 0)
   {
      png_calculate_crc(png_ptr, data, length);
      png_write_data(png_ptr, data, length);
   }
}

/* Finish a chunk started with png_write_chunk_start(). */
void
png_write_chunk_end(png_structp png_ptr)
{
   png_byte buf[4];

   /* write the crc */
   png_save_uint_32(buf, png_ptr->crc);

   png_write_data(png_ptr, buf, (png_size_t)4);
}

/* Simple function to write the signature.  If we have already written
 * the magic bytes of the signature, or more likely, the PNG stream is
 * being embedded into another stream and doesn't need its own signature,
 * we should call png_set_sig_bytes() to tell libpng how many of the
 * bytes have already been written.
 */
void
png_write_sig(png_structp png_ptr)
{
   /* write the rest of the 8 byte signature */
   png_write_data(png_ptr, &png_sig[png_ptr->sig_bytes],
      (png_size_t)8 - png_ptr->sig_bytes);
}

/* Write the IHDR chunk, and update the png_struct with the necessary
 * information.  Note that the rest of this code depends upon this
 * information being correct.
 */
void
png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
   int bit_depth, int color_type, int compression_type, int filter_type,
   int interlace_type)
{
   png_byte buf[13]; /* buffer to store the IHDR info */

   png_debug(1, "in png_write_IHDR\n");
   /* Check that we have valid input data from the application info */
   switch (color_type)
   {
      case PNG_COLOR_TYPE_GRAY:
         switch (bit_depth)
         {
            case 1:
            case 2:
            case 4:
            case 8:
            case 16: png_ptr->channels = 1; break;
            default: png_error(png_ptr,"Invalid bit depth for grayscale image");
         }
         break;
      case PNG_COLOR_TYPE_RGB:
         if (bit_depth != 8 && bit_depth != 16)
            png_error(png_ptr, "Invalid bit depth for RGB image");
         png_ptr->channels = 3;
         break;
      case PNG_COLOR_TYPE_PALETTE:
         switch (bit_depth)
         {
            case 1:
            case 2:
            case 4:
            case 8: png_ptr->channels = 1; break;
            default: png_error(png_ptr, "Invalid bit depth for paletted image");
         }
         break;
      case PNG_COLOR_TYPE_GRAY_ALPHA:
         if (bit_depth != 8 && bit_depth != 16)
            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
         png_ptr->channels = 2;
         break;
      case PNG_COLOR_TYPE_RGB_ALPHA:
         if (bit_depth != 8 && bit_depth != 16)
            png_error(png_ptr, "Invalid bit depth for RGBA image");
         png_ptr->channels = 4;
         break;
      default:
         png_error(png_ptr, "Invalid image color type specified");
   }

   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
   {
      png_warning(png_ptr, "Invalid compression type specified");
      compression_type = PNG_COMPRESSION_TYPE_BASE;
   }

   if (filter_type != PNG_FILTER_TYPE_BASE)
   {
      png_warning(png_ptr, "Invalid filter type specified");
      filter_type = PNG_FILTER_TYPE_BASE;
   }

#ifdef PNG_WRITE_INTERLACING_SUPPORTED
   if (interlace_type != PNG_INTERLACE_NONE &&
      interlace_type != PNG_INTERLACE_ADAM7)
   {
      png_warning(png_ptr, "Invalid interlace type specified");
      interlace_type = PNG_INTERLACE_ADAM7;
   }
#else
   interlace_type=PNG_INTERLACE_NONE;
#endif

   /* save off the relevent information */
   png_ptr->bit_depth = (png_byte)bit_depth;
   png_ptr->color_type = (png_byte)color_type;
   png_ptr->interlaced = (png_byte)interlace_type;
   png_ptr->width = width;
   png_ptr->height = height;

   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
   png_ptr->rowbytes = ((width * (png_size_t)png_ptr->pixel_depth + 7) >> 3);
   /* set the usr info, so any transformations can modify it */
   png_ptr->usr_width = png_ptr->width;
   png_ptr->usr_bit_depth = png_ptr->bit_depth;
   png_ptr->usr_channels = png_ptr->channels;

   /* pack the header information into the buffer */
   png_save_uint_32(buf, width);
   png_save_uint_32(buf + 4, height);
   buf[8] = (png_byte)bit_depth;
   buf[9] = (png_byte)color_type;
   buf[10] = (png_byte)compression_type;
   buf[11] = (png_byte)filter_type;
   buf[12] = (png_byte)interlace_type;

   /* write the chunk */
   png_write_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);

   /* initialize zlib with PNG info */
   png_ptr->zstream.zalloc = png_zalloc;
   png_ptr->zstream.zfree = png_zfree;
   png_ptr->zstream.opaque = (voidpf)png_ptr;
   if (!(png_ptr->do_filter))
   {
      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
         png_ptr->bit_depth < 8)
         png_ptr->do_filter = PNG_FILTER_NONE;
      else
         png_ptr->do_filter = PNG_ALL_FILTERS;
   }
   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
   {
      if (png_ptr->do_filter != PNG_FILTER_NONE)
         png_ptr->zlib_strategy = Z_FILTERED;
      else
         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
   }
   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
      png_ptr->zlib_mem_level = 8;
   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
      png_ptr->zlib_window_bits = 15;
   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
      png_ptr->zlib_method = 8;
   deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
      png_ptr->zlib_method, png_ptr->zlib_window_bits,
      png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
   png_ptr->zstream.next_out = png_ptr->zbuf;
   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

   png_ptr->mode = PNG_HAVE_IHDR;
}

/* write the palette.  We are careful not to trust png_color to be in the
 * correct order for PNG, so people can redefine it to any convenient
 * structure.
 */
void
png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
{
   png_uint_32 i;
   png_colorp pal_ptr;
   png_byte buf[3];

   png_debug(1, "in png_write_PLTE\n");
   if (num_pal == 0 || num_pal > 256)
   {
      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
         png_error(png_ptr, "Invalid number of colors in palette");
      }
      else
      {
         png_warning(png_ptr, "Invalid number of colors in palette");
         return;
      }
   }

   png_ptr->num_palette = (png_uint_16)num_pal;
   png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);

   png_write_chunk_start(png_ptr, png_PLTE, num_pal * 3);
   for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
   {
      buf[0] = pal_ptr->red;
      buf[1] = pal_ptr->green;
      buf[2] = pal_ptr->blue;
      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
   }
   png_write_chunk_end(png_ptr);
   png_ptr->mode |= PNG_HAVE_PLTE;
}

/* write an IDAT chunk */
void
png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_debug(1, "in png_write_IDAT\n");
   png_write_chunk(png_ptr, png_IDAT, data, length);
   png_ptr->mode |= PNG_HAVE_IDAT;
}

/* write an IEND chunk */
void
png_write_IEND(png_structp png_ptr)
{
   png_debug(1, "in png_write_IEND\n");
   png_write_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
   png_ptr->mode |= PNG_HAVE_IEND;
}

#if defined(PNG_WRITE_gAMA_SUPPORTED)
/* write a gAMA chunk */
void
png_write_gAMA(png_structp png_ptr, double file_gamma)
{
   png_uint_32 igamma;
   png_byte buf[4];

   png_debug(1, "in png_write_gAMA\n");
   /* file_gamma is saved in 1/1000000ths */
   igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
   png_save_uint_32(buf, igamma);
   png_write_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
}
#endif

#if defined(PNG_WRITE_sRGB_SUPPORTED)
/* write a sRGB chunk */
void
png_write_sRGB(png_structp png_ptr, int srgb_intent)
{
   png_byte buf[1];

   png_debug(1, "in png_write_sRGB\n");
   if(srgb_intent >= PNG_sRGB_INTENT_LAST)
         png_warning(png_ptr,
            "Invalid sRGB rendering intent specified");
   buf[0]=(png_byte)srgb_intent;
   png_write_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
}
#endif

#if defined(PNG_WRITE_sBIT_SUPPORTED)
/* write the sBIT chunk */
void
png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
{
   png_byte buf[4];
   png_size_t size;

   png_debug(1, "in png_write_sBIT\n");
   /* make sure we don't depend upon the order of PNG_COLOR_8 */
   if (color_type & PNG_COLOR_MASK_COLOR)
   {
      png_byte maxbits;

      maxbits = color_type==PNG_COLOR_TYPE_PALETTE ? 8 : png_ptr->usr_bit_depth;
      if (sbit->red == 0 || sbit->red > maxbits ||
          sbit->green == 0 || sbit->green > maxbits ||
          sbit->blue == 0 || sbit->blue > maxbits)
      {
         png_warning(png_ptr, "Invalid sBIT depth specified");
         return;
      }
      buf[0] = sbit->red;
      buf[1] = sbit->green;
      buf[2] = sbit->blue;
      size = 3;
   }
   else
   {
      if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
      {
         png_warning(png_ptr, "Invalid sBIT depth specified");
         return;
      }
      buf[0] = sbit->gray;
      size = 1;
   }

   if (color_type & PNG_COLOR_MASK_ALPHA)
   {
      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
      {
         png_warning(png_ptr, "Invalid sBIT depth specified");
         return;
      }
      buf[size++] = sbit->alpha;
   }

   png_write_chunk(png_ptr, png_sBIT, buf, size);