tinyjpeg.c

M8手机图片查看器

     sampling_factor = *stream++;
     Q_table = *stream++;
     c = &priv->component_infos[i];
#if SANITY_CHECK
     c->cid = cid;
     if (Q_table >= COMPONENTS)
       error("Bad Quantization table index (got %d, max allowed %d)\n", Q_table, COMPONENTS-1);
#endif
     c->Vfactor = sampling_factor&0xf;
     c->Hfactor = sampling_factor>>4;
     c->Q_table = priv->Q_tables[Q_table];
     trace("Component:%d  factor:%dx%d  Quantization table:%d\n",
           cid, c->Hfactor, c->Hfactor, Q_table );

  }
  priv->width = width;
  priv->height = height;

  trace("< SOF marker\n");

  return 0;
}

static int parse_SOS(struct jdec_private *priv, const unsigned char *stream)
{
  unsigned int i, cid, table;
  unsigned int nr_components = stream[2];

  trace("> SOS marker\n");

#if SANITY_CHECK
  if (nr_components != 3)
    error("We only support YCbCr image\n");
#endif

  stream += 3;
  for (i=0;i<nr_components;i++) {
     cid = *stream++;
     table = *stream++;
#if SANITY_CHECK
     if ((table&0xf)>=4)
	error("We do not support more than 2 AC Huffman table\n");
     if ((table>>4)>=4)
	error("We do not support more than 2 DC Huffman table\n");
     if (cid != priv->component_infos[i].cid)
        error("SOS cid order (%d:%d) isn't compatible with the SOF marker (%d:%d)\n",
	      i, cid, i, priv->component_infos[i].cid);
     trace("ComponentId:%d  tableAC:%d tableDC:%d\n", cid, table&0xf, table>>4);
#endif
     priv->component_infos[i].AC_table = &priv->HTAC[table&0xf];
     priv->component_infos[i].DC_table = &priv->HTDC[table>>4];
  }
  priv->stream = stream+3;
  trace("< SOS marker\n");
  return 0;
}

static int parse_DHT(struct jdec_private *priv, const unsigned char *stream)
{
  unsigned int count, i;
  unsigned char huff_bits[17];
  int length, index;

  length = be16_to_cpu(stream) - 2;
  stream += 2;	/* Skip length */

  trace("> DHT marker (length=%d)\n", length);

  while (length>0) {
     index = *stream++;

     /* We need to calculate the number of bytes 'vals' will takes */
     huff_bits[0] = 0;
     count = 0;
     for (i=1; i<17; i++) {
	huff_bits[i] = *stream++;
	count += huff_bits[i];
     }
#if SANITY_CHECK
     if (count >= HUFFMAN_BITS_SIZE)
       error("No more than %d bytes is allowed to describe a huffman table", HUFFMAN_BITS_SIZE);
     if ( (index &0xf) >= HUFFMAN_TABLES)
       error("No more than %d Huffman tables is supported (got %d)\n", HUFFMAN_TABLES, index&0xf);
     trace("Huffman table %s[%d] length=%d\n", (index&0xf0)?"AC":"DC", index&0xf, count);
#endif

     if (index & 0xf0 )
       build_huffman_table(huff_bits, stream, &priv->HTAC[index&0xf]);
     else
       build_huffman_table(huff_bits, stream, &priv->HTDC[index&0xf]);

     length -= 1;
     length -= 16;
     length -= count;
     stream += count;
  }
  trace("< DHT marker\n");
  return 0;
}

static int parse_DRI(struct jdec_private *priv, const unsigned char *stream)
{
  unsigned int length;

  trace("> DRI marker\n");

  length = be16_to_cpu(stream);

#if SANITY_CHECK
  if (length != 4)
    error("Length of DRI marker need to be 4\n");
#endif

  priv->restart_interval = be16_to_cpu(stream+2);

#if DEBUG
  trace("Restart interval = %d\n", priv->restart_interval);
#endif

  trace("< DRI marker\n");

  return 0;
}



static void resync(struct jdec_private *priv)
{
  int i;

  /* Init DC coefficients */
  for (i=0; i<COMPONENTS; i++)
     priv->component_infos[i].previous_DC = 0;

  priv->reservoir = 0;
  priv->nbits_in_reservoir = 0;
  if (priv->restart_interval > 0)
    priv->restarts_to_go = priv->restart_interval;
  else
    priv->restarts_to_go = -1;
}

static int find_next_rst_marker(struct jdec_private *priv)
{
  int rst_marker_found = 0;
  int marker;
  const unsigned char *stream = priv->stream;

  /* Parse marker */
  while (!rst_marker_found)
   {
     while (*stream++ != 0xff)
      {
	if (stream >= priv->stream_end)
	  error("EOF while search for a RST marker.");
      }
     /* Skip any padding ff byte (this is normal) */
     while (*stream == 0xff)
       stream++;

     marker = *stream++;
     if ((RST+priv->last_rst_marker_seen) == marker)
       rst_marker_found = 1;
     else if (marker >= RST && marker <= RST7)
       error("Wrong Reset marker found, abording");
     else if (marker == EOI)
       return 0;
   }
  trace("RST Marker %d found at offset %d\n", priv->last_rst_marker_seen, stream - priv->stream_begin);

  priv->stream = stream;
  priv->last_rst_marker_seen++;
  priv->last_rst_marker_seen &= 7;

  return 0;
}

static int parse_JFIF(struct jdec_private *priv, const unsigned char *stream)
{
  int chuck_len;
  int marker;
  int sos_marker_found = 0;
  int dht_marker_found = 0;
  const unsigned char *next_chunck;

  /* Parse marker */
  while (!sos_marker_found)
   {
     if (*stream++ != 0xff)
       goto bogus_jpeg_format;
     /* Skip any padding ff byte (this is normal) */
     while (*stream == 0xff)
       stream++;

     marker = *stream++;
     chuck_len = be16_to_cpu(stream);
     next_chunck = stream + chuck_len;
     switch (marker)
      {
       case SOF:
	 if (parse_SOF(priv, stream) < 0)
	   return -1;
	 break;
       case DQT:
	 if (parse_DQT(priv, stream) < 0)
	   return -1;
	 break;
       case SOS:
	 if (parse_SOS(priv, stream) < 0)
	   return -1;
	 sos_marker_found = 1;
	 break;
       case DHT:
	 if (parse_DHT(priv, stream) < 0)
	   return -1;
	 dht_marker_found = 1;
	 break;
       case DRI:
	 if (parse_DRI(priv, stream) < 0)
	   return -1;
	 break;
       default:
	 trace("> Unknown marker %2.2x\n", marker);
	 break;
      }

     stream = next_chunck;
   }

  if (!dht_marker_found) {
    trace("No Huffman table loaded, using the default one\n");
    build_default_huffman_tables(priv);
  }

#ifdef SANITY_CHECK
  if (   (priv->component_infos[cY].Hfactor < priv->component_infos[cCb].Hfactor)
      || (priv->component_infos[cY].Hfactor < priv->component_infos[cCr].Hfactor))
    error("Horizontal sampling factor for Y should be greater than horitontal sampling factor for Cb or Cr\n");
  if (   (priv->component_infos[cY].Vfactor < priv->component_infos[cCb].Vfactor)
      || (priv->component_infos[cY].Vfactor < priv->component_infos[cCr].Vfactor))
    error("Vertical sampling factor for Y should be greater than vertical sampling factor for Cb or Cr\n");
  if (   (priv->component_infos[cCb].Hfactor!=1) 
      || (priv->component_infos[cCr].Hfactor!=1)
      || (priv->component_infos[cCb].Vfactor!=1)
      || (priv->component_infos[cCr].Vfactor!=1))
    error("Sampling other than 1x1 for Cr and Cb is not supported");
#endif

  return 0;
bogus_jpeg_format:
  trace("Bogus jpeg format\n");
  return -1;
}

/*******************************************************************************
 *
 * Functions exported of the library.
 *
 * Note: Some applications can access directly to internal pointer of the
 * structure. It's is not recommended, but if you have many images to
 * uncompress with the same parameters, some functions can be called to speedup
 * the decoding.
 *
 ******************************************************************************/

/**
 * Allocate a new tinyjpeg decoder object.
 *
 * Before calling any other functions, an object need to be called.
 */
struct jdec_private *tinyjpeg_init(void)
{
  struct jdec_private *priv;
 
  priv = (struct jdec_private *)calloc(1, sizeof(struct jdec_private));
  if (priv == NULL)
    return NULL;
  return priv;
}

/**
 * Free a tinyjpeg object.
 *
 * No others function can be called after this one.
 */
void tinyjpeg_free(struct jdec_private *priv)
{
  int i;
  for (i=0; i<COMPONENTS; i++) {
     if (priv->components[i])
       free(priv->components[i]);
     priv->components[i] = NULL;
  }
  free(priv);
}

/**
 * Initialize the tinyjpeg object and prepare the decoding of the stream.
 *
 * Check if the jpeg can be decoded with this jpeg decoder.
 * Fill some table used for preprocessing.
 */
int tinyjpeg_parse_header(struct jdec_private *priv, const unsigned char *buf, unsigned int size)
{
  int ret;

  /* Identify the file */
  if ((buf[0] != 0xFF) || (buf[1] != SOI))
    error("Not a JPG file ?\n");

  priv->stream_begin = buf+2;
  priv->stream_length = size-2;
  priv->stream_end = priv->stream_begin + priv->stream_length;

  ret = parse_JFIF(priv, priv->stream_begin);

  return ret;
}

static const decode_MCU_fct decode_mcu_3comp_table[4] = {
   decode_MCU_1x1_3planes,
   decode_MCU_1x2_3planes,
   decode_MCU_2x1_3planes,
   decode_MCU_2x2_3planes,
};

static const decode_MCU_fct decode_mcu_1comp_table[4] = {
   decode_MCU_1x1_1plane,
   decode_MCU_1x2_1plane,
   decode_MCU_2x1_1plane,
   decode_MCU_2x2_1plane,
};

static const convert_colorspace_fct convert_colorspace_yuv420p[4] = {
   YCrCB_to_YUV420P_1x1,
   YCrCB_to_YUV420P_1x2,
   YCrCB_to_YUV420P_2x1,
   YCrCB_to_YUV420P_2x2,
};

static const convert_colorspace_fct convert_colorspace_rgb24[4] = {
   YCrCB_to_RGB24_1x1,
   YCrCB_to_RGB24_1x2,
   YCrCB_to_RGB24_2x1,
   YCrCB_to_RGB24_2x2,
};

static const convert_colorspace_fct convert_colorspace_bgr24[4] = {
   YCrCB_to_BGR24_1x1,
   YCrCB_to_BGR24_1x2,
   YCrCB_to_BGR24_2x1,
   YCrCB_to_BGR24_2x2,
};

static const convert_colorspace_fct convert_colorspace_grey[4] = {
   YCrCB_to_Grey_1x1,
   YCrCB_to_Grey_1x2,
   YCrCB_to_Grey_2x1,
   YCrCB_to_Grey_2x2,
};

/**
 * Decode and convert the jpeg image into @pixfmt@ image
 *
 * Note: components will be automaticaly allocated if no memory is attached.
 */
int tinyjpeg_decode(struct jdec_private *priv, int pixfmt)
{
  unsigned int x, y, xstride_by_mcu, ystride_by_mcu;
  unsigned int bytes_per_blocklines[3], bytes_per_mcu[3];
  decode_MCU_fct decode_MCU;
  const decode_MCU_fct *decode_mcu_table;
  const convert_colorspace_fct *colorspace_array_conv;
  convert_colorspace_fct convert_to_pixfmt;

  if (setjmp(priv->jump_state))
    return -1;

  /* To keep gcc happy initialize some array */
  bytes_per_mcu[1] = 0;
  bytes_per_mcu[2] = 0;
  bytes_per_blocklines[1] = 0;
  bytes_per_blocklines[2] = 0;

  decode_mcu_table = decode_mcu_3comp_table;
  switch (pixfmt) {
     case TINYJPEG_FMT_YUV420P:
       colorspace_array_conv = convert_colorspace_yuv420p;
       if (priv->components[0] == NULL)
	 priv->components[0] = (uint8_t *)malloc(priv->width * priv->height);
       if (priv->components[1] == NULL)
	 priv->components[1] = (uint8_t *)malloc(priv->width * priv->height/4);
       if (priv->components[2] == NULL)
	 priv->components[2] = (uint8_t *)malloc(priv->width * priv->height/4);
       bytes_per_blocklines[0] = priv->width;
       bytes_per_blocklines[1] = priv->width/4;
       bytes_per_blocklines[2] = priv->width/4;
       bytes_per_mcu[0] = 8;
       bytes_per_mcu[1] = 4;
       bytes_per_mcu[2] = 4;
       break;

     case TINYJPEG_FMT_RGB24:
       colorspace_array_conv = convert_colorspace_rgb24;
       if (priv->components[0] == NULL)
	 priv->components[0] = (uint8_t *)malloc(priv->width * priv->height * 3);
       bytes_per_blocklines[0] = priv->width * 3;
       bytes_per_mcu[0] = 3*8;
       break;

     case TINYJPEG_FMT_BGR24:
       colorspace_array_conv = convert_colorspace_bgr24;
       if (priv->components[0] == NULL)
	 priv->components[0] = (uint8_t *)malloc(priv->width * priv->height * 3);
       bytes_per_blocklines[0] = priv->width * 3;
       bytes_per_mcu[0] = 3*8;
       break;

     case TINYJPEG_FMT_GREY:
       decode_mcu_table = decode_mcu_1comp_table;
       colorspace_array_conv = convert_colorspace_grey;
       if (priv->components[0] == NULL)
	 priv->components[0] = (uint8_t *)malloc(priv->width * priv->height);
       bytes_per_blocklines[0] = priv->width;
       bytes_per_mcu[0] = 8;
       break;

     default:
       trace("Bad pixel format\n");
       return -1;
  }

  xstride_by_mcu = ystride_by_mcu = 8;
  if ((priv->component_infos[cY].Hfactor | priv->component_infos[cY].Vfactor) == 1) {
     decode_MCU = decode_mcu_table[0];
     convert_to_pixfmt = colorspace_array_conv[0];
     trace("Use decode 1x1 sampling\n");
  } else if (priv->component_infos[cY].Hfactor == 1) {
     decode_MCU = decode_mcu_table[1];
     convert_to_pixfmt = colorspace_array_conv[1];
     ystride_by_mcu = 16;
     trace("Use decode 1x2 sampling (not supported)\n");
  } else if (priv->component_infos[cY].Vfactor == 2) {
     decode_MCU = decode_mcu_table[3];
     convert_to_pixfmt = colorspace_array_conv[3];
     xstride_by_mcu = 16;
     ystride_by_mcu = 16;
     trace("Use decode 2x2 sampling\n");
  } else {
     decode_MCU = decode_mcu_table[2];
     convert_to_pixfmt = colorspace_array_conv[2];
     xstride_by_mcu = 16;
     trace("Use decode 2x1 sampling\n");
  }

  resync(priv);

  /* Don't forget to that block can be either 8 or 16 lines */
  bytes_per_blocklines[0] *= ystride_by_mcu;
  bytes_per_blocklines[1] *= ystride_by_mcu;
  bytes_per_blocklines[2] *= ystride_by_mcu;

  bytes_per_mcu[0] *= xstride_by_mcu/8;
  bytes_per_mcu[1] *= xstride_by_mcu/8;
  bytes_per_mcu[2] *= xstride_by_mcu/8;

  /* Just the decode the image by macroblock (size is 8x8, 8x16, or 16x16) */
  for (y=0; y < priv->height/ystride_by_mcu; y++)
   {
     //trace("Decoding row %d\n", y);
     priv->plane[0] = priv->components[0] + (y * bytes_per_blocklines[0]);
     priv->plane[1] = priv->components[1] + (y * bytes_per_blocklines[1]);
     priv->plane[2] = priv->components[2] + (y * bytes_per_blocklines[2]);
     for (x=0; x < priv->width; x+=xstride_by_mcu)
      {
	decode_MCU(priv);
	convert_to_pixfmt(priv);
	priv->plane[0] += bytes_per_mcu[0];
	priv->plane[1] += bytes_per_mcu[1];
	priv->plane[2] += bytes_per_mcu[2];
	if (priv->restarts_to_go>0)
	 {
	   priv->restarts_to_go--;
	   if (priv->restarts_to_go == 0)
	    {
	      priv->stream -= (priv->nbits_in_reservoir/8);
	      resync(priv);
	      if (find_next_rst_marker(priv) < 0)
		return -1;
	    }
	 }
      }
   }

  trace("Input file size: %d\n", priv->stream_length+2);
  trace("Input bytes actually read: %d\n", priv->stream - priv->stream_begin + 2);

  return 0;
}

const char *tinyjpeg_get_errorstring(struct jdec_private *priv)
{
  /* FIXME: the error string must be store in the context */
  priv = priv;
  return error_string;
}

void tinyjpeg_get_size(struct jdec_private *priv, unsigned int *width, unsigned int *height)
{
  *width = priv->width;
  *height = priv->height;
}

int tinyjpeg_get_components(struct jdec_private *priv, unsigned char **components)
{
  int i;
  for (i=0; priv->components[i] && i<COMPONENTS; i++)
    components[i] = priv->components[i];
  return 0;
}

int tinyjpeg_set_components(struct jdec_private *priv, unsigned char **components, unsigned int ncomponents)
{
  unsigned int i;
  if (ncomponents > COMPONENTS)
    ncomponents = COMPONENTS;
  for (i=0; i<ncomponents; i++)
    priv->components[i] = components[i];
  return 0;
}

int tinyjpeg_set_flags(struct jdec_private *priv, int flags)
{
  int oldflags = priv->flags;
  priv->flags = flags;
  return oldflags;
}