www.pudn.com > imgport.rar > jcmarker.c, change:2008-11-05,size:17909b


/* 
 * jcmarker.c 
 * 
 * Copyright (C) 1991-1998, Thomas G. Lane. 
 * This file is part of the Independent JPEG Group's software. 
 * For conditions of distribution and use, see the accompanying README file. 
 * 
 * This file contains routines to write JPEG datastream markers. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
typedef enum {			/* JPEG marker codes */ 
  M_SOF0  = 0xc0, 
  M_SOF1  = 0xc1, 
  M_SOF2  = 0xc2, 
  M_SOF3  = 0xc3, 
   
  M_SOF5  = 0xc5, 
  M_SOF6  = 0xc6, 
  M_SOF7  = 0xc7, 
   
  M_JPG   = 0xc8, 
  M_SOF9  = 0xc9, 
  M_SOF10 = 0xca, 
  M_SOF11 = 0xcb, 
   
  M_SOF13 = 0xcd, 
  M_SOF14 = 0xce, 
  M_SOF15 = 0xcf, 
   
  M_DHT   = 0xc4, 
   
  M_DAC   = 0xcc, 
   
  M_RST0  = 0xd0, 
  M_RST1  = 0xd1, 
  M_RST2  = 0xd2, 
  M_RST3  = 0xd3, 
  M_RST4  = 0xd4, 
  M_RST5  = 0xd5, 
  M_RST6  = 0xd6, 
  M_RST7  = 0xd7, 
   
  M_SOI   = 0xd8, 
  M_EOI   = 0xd9, 
  M_SOS   = 0xda, 
  M_DQT   = 0xdb, 
  M_DNL   = 0xdc, 
  M_DRI   = 0xdd, 
  M_DHP   = 0xde, 
  M_EXP   = 0xdf, 
   
  M_APP0  = 0xe0, 
  M_APP1  = 0xe1, 
  M_APP2  = 0xe2, 
  M_APP3  = 0xe3, 
  M_APP4  = 0xe4, 
  M_APP5  = 0xe5, 
  M_APP6  = 0xe6, 
  M_APP7  = 0xe7, 
  M_APP8  = 0xe8, 
  M_APP9  = 0xe9, 
  M_APP10 = 0xea, 
  M_APP11 = 0xeb, 
  M_APP12 = 0xec, 
  M_APP13 = 0xed, 
  M_APP14 = 0xee, 
  M_APP15 = 0xef, 
   
  M_JPG0  = 0xf0, 
  M_JPG13 = 0xfd, 
  M_COM   = 0xfe, 
   
  M_TEM   = 0x01, 
   
  M_ERROR = 0x100 
} JPEG_MARKER; 
 
 
/* Private state */ 
 
typedef struct { 
  struct jpeg_marker_writer pub; /* public fields */ 
 
  unsigned int last_restart_interval; /* last DRI value emitted; 0 after SOI */ 
} my_marker_writer; 
 
typedef my_marker_writer * my_marker_ptr; 
 
 
/* 
 * Basic output routines. 
 * 
 * Note that we do not support suspension while writing a marker. 
 * Therefore, an application using suspension must ensure that there is 
 * enough buffer space for the initial markers (typ. 600-700 bytes) before 
 * calling jpeg_start_compress, and enough space to write the trailing EOI 
 * (a few bytes) before calling jpeg_finish_compress.  Multipass compression 
 * modes are not supported at all with suspension, so those two are the only 
 * points where markers will be written. 
 */ 
 
LOCAL(void) 
emit_byte (j_compress_ptr cinfo, int val) 
/* Emit a byte */ 
{ 
  struct jpeg_destination_mgr * dest = cinfo->dest; 
 
  *(dest->next_output_byte)++ = (JOCTET) val; 
  if (--dest->free_in_buffer == 0) { 
    if (! (*dest->empty_output_buffer) (cinfo)) 
      ERREXIT(cinfo, JERR_CANT_SUSPEND); 
  } 
} 
 
 
LOCAL(void) 
emit_marker (j_compress_ptr cinfo, JPEG_MARKER mark) 
/* Emit a marker code */ 
{ 
  emit_byte(cinfo, 0xFF); 
  emit_byte(cinfo, (int) mark); 
} 
 
 
LOCAL(void) 
emit_2bytes (j_compress_ptr cinfo, int value) 
/* Emit a 2-byte integer; these are always MSB first in JPEG files */ 
{ 
  emit_byte(cinfo, (value >> 8) & 0xFF); 
  emit_byte(cinfo, value & 0xFF); 
} 
 
 
/* 
 * Routines to write specific marker types. 
 */ 
 
LOCAL(int) 
emit_dqt (j_compress_ptr cinfo, int index) 
/* Emit a DQT marker */ 
/* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */ 
{ 
  JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[index]; 
  int prec; 
  int i; 
 
  if (qtbl == NULL) 
    ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, index); 
 
  prec = 0; 
  for (i = 0; i < DCTSIZE2; i++) { 
    if (qtbl->quantval[i] > 255) 
      prec = 1; 
  } 
 
  if (! qtbl->sent_table) { 
    emit_marker(cinfo, M_DQT); 
 
    emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2); 
 
    emit_byte(cinfo, index + (prec<<4)); 
 
    for (i = 0; i < DCTSIZE2; i++) { 
      /* The table entries must be emitted in zigzag order. */ 
      unsigned int qval = qtbl->quantval[jpeg_natural_order[i]]; 
      if (prec) 
	emit_byte(cinfo, (int) (qval >> 8)); 
      emit_byte(cinfo, (int) (qval & 0xFF)); 
    } 
 
    qtbl->sent_table = TRUE; 
  } 
 
  return prec; 
} 
 
 
LOCAL(void) 
emit_dht (j_compress_ptr cinfo, int index, boolean is_ac) 
/* Emit a DHT marker */ 
{ 
  JHUFF_TBL * htbl; 
  int length, i; 
   
  if (is_ac) { 
    htbl = cinfo->ac_huff_tbl_ptrs[index]; 
    index += 0x10;		/* output index has AC bit set */ 
  } else { 
    htbl = cinfo->dc_huff_tbl_ptrs[index]; 
  } 
 
  if (htbl == NULL) 
    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, index); 
   
  if (! htbl->sent_table) { 
    emit_marker(cinfo, M_DHT); 
     
    length = 0; 
    for (i = 1; i <= 16; i++) 
      length += htbl->bits[i]; 
     
    emit_2bytes(cinfo, length + 2 + 1 + 16); 
    emit_byte(cinfo, index); 
     
    for (i = 1; i <= 16; i++) 
      emit_byte(cinfo, htbl->bits[i]); 
     
    for (i = 0; i < length; i++) 
      emit_byte(cinfo, htbl->huffval[i]); 
     
    htbl->sent_table = TRUE; 
  } 
} 
 
 
LOCAL(void) 
emit_dac (j_compress_ptr cinfo) 
/* Emit a DAC marker */ 
/* Since the useful info is so small, we want to emit all the tables in */ 
/* one DAC marker.  Therefore this routine does its own scan of the table. */ 
{ 
#ifdef C_ARITH_CODING_SUPPORTED 
  char dc_in_use[NUM_ARITH_TBLS]; 
  char ac_in_use[NUM_ARITH_TBLS]; 
  int length, i; 
  jpeg_component_info *compptr; 
   
  for (i = 0; i < NUM_ARITH_TBLS; i++) 
    dc_in_use[i] = ac_in_use[i] = 0; 
   
  for (i = 0; i < cinfo->comps_in_scan; i++) { 
    compptr = cinfo->cur_comp_info[i]; 
    dc_in_use[compptr->dc_tbl_no] = 1; 
    ac_in_use[compptr->ac_tbl_no] = 1; 
  } 
   
  length = 0; 
  for (i = 0; i < NUM_ARITH_TBLS; i++) 
    length += dc_in_use[i] + ac_in_use[i]; 
   
  emit_marker(cinfo, M_DAC); 
   
  emit_2bytes(cinfo, length*2 + 2); 
   
  for (i = 0; i < NUM_ARITH_TBLS; i++) { 
    if (dc_in_use[i]) { 
      emit_byte(cinfo, i); 
      emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4)); 
    } 
    if (ac_in_use[i]) { 
      emit_byte(cinfo, i + 0x10); 
      emit_byte(cinfo, cinfo->arith_ac_K[i]); 
    } 
  } 
#endif /* C_ARITH_CODING_SUPPORTED */ 
} 
 
 
LOCAL(void) 
emit_dri (j_compress_ptr cinfo) 
/* Emit a DRI marker */ 
{ 
  emit_marker(cinfo, M_DRI); 
   
  emit_2bytes(cinfo, 4);	/* fixed length */ 
 
  emit_2bytes(cinfo, (int) cinfo->restart_interval); 
} 
 
 
LOCAL(void) 
emit_sof (j_compress_ptr cinfo, JPEG_MARKER code) 
/* Emit a SOF marker */ 
{ 
  int ci; 
  jpeg_component_info *compptr; 
   
  emit_marker(cinfo, code); 
   
  emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */ 
 
  /* Make sure image isn't bigger than SOF field can handle */ 
  if ((long) cinfo->image_height > 65535L || 
      (long) cinfo->image_width > 65535L) 
    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) 65535); 
 
  emit_byte(cinfo, cinfo->data_precision); 
  emit_2bytes(cinfo, (int) cinfo->image_height); 
  emit_2bytes(cinfo, (int) cinfo->image_width); 
 
  emit_byte(cinfo, cinfo->num_components); 
 
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
       ci++, compptr++) { 
    emit_byte(cinfo, compptr->component_id); 
    emit_byte(cinfo, (compptr->h_samp_factor << 4) + compptr->v_samp_factor); 
    emit_byte(cinfo, compptr->quant_tbl_no); 
  } 
} 
 
 
LOCAL(void) 
emit_sos (j_compress_ptr cinfo) 
/* Emit a SOS marker */ 
{ 
  int i, td, ta; 
  jpeg_component_info *compptr; 
   
  emit_marker(cinfo, M_SOS); 
   
  emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */ 
   
  emit_byte(cinfo, cinfo->comps_in_scan); 
   
  for (i = 0; i < cinfo->comps_in_scan; i++) { 
    compptr = cinfo->cur_comp_info[i]; 
    emit_byte(cinfo, compptr->component_id); 
    td = compptr->dc_tbl_no; 
    ta = compptr->ac_tbl_no; 
    if (cinfo->progressive_mode) { 
      /* Progressive mode: only DC or only AC tables are used in one scan; 
       * furthermore, Huffman coding of DC refinement uses no table at all. 
       * We emit 0 for unused field(s); this is recommended by the P&M text 
       * but does not seem to be specified in the standard. 
       */ 
      if (cinfo->Ss == 0) { 
	ta = 0;			/* DC scan */ 
	if (cinfo->Ah != 0 && !cinfo->arith_code) 
	  td = 0;		/* no DC table either */ 
      } else { 
	td = 0;			/* AC scan */ 
      } 
    } 
    emit_byte(cinfo, (td << 4) + ta); 
  } 
 
  emit_byte(cinfo, cinfo->Ss); 
  emit_byte(cinfo, cinfo->Se); 
  emit_byte(cinfo, (cinfo->Ah << 4) + cinfo->Al); 
} 
 
 
LOCAL(void) 
emit_jfif_app0 (j_compress_ptr cinfo) 
/* Emit a JFIF-compliant APP0 marker */ 
{ 
  /* 
   * Length of APP0 block	(2 bytes) 
   * Block ID			(4 bytes - ASCII "JFIF") 
   * Zero byte			(1 byte to terminate the ID string) 
   * Version Major, Minor	(2 bytes - major first) 
   * Units			(1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm) 
   * Xdpu			(2 bytes - dots per unit horizontal) 
   * Ydpu			(2 bytes - dots per unit vertical) 
   * Thumbnail X size		(1 byte) 
   * Thumbnail Y size		(1 byte) 
   */ 
   
  emit_marker(cinfo, M_APP0); 
   
  emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */ 
 
  emit_byte(cinfo, 0x4A);	/* Identifier: ASCII "JFIF" */ 
  emit_byte(cinfo, 0x46); 
  emit_byte(cinfo, 0x49); 
  emit_byte(cinfo, 0x46); 
  emit_byte(cinfo, 0); 
  emit_byte(cinfo, cinfo->JFIF_major_version); /* Version fields */ 
  emit_byte(cinfo, cinfo->JFIF_minor_version); 
  emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */ 
  emit_2bytes(cinfo, (int) cinfo->X_density); 
  emit_2bytes(cinfo, (int) cinfo->Y_density); 
  emit_byte(cinfo, 0);		/* No thumbnail image */ 
  emit_byte(cinfo, 0); 
} 
 
 
LOCAL(void) 
emit_adobe_app14 (j_compress_ptr cinfo) 
/* Emit an Adobe APP14 marker */ 
{ 
  /* 
   * Length of APP14 block	(2 bytes) 
   * Block ID			(5 bytes - ASCII "Adobe") 
   * Version Number		(2 bytes - currently 100) 
   * Flags0			(2 bytes - currently 0) 
   * Flags1			(2 bytes - currently 0) 
   * Color transform		(1 byte) 
   * 
   * Although Adobe TN 5116 mentions Version = 101, all the Adobe files 
   * now in circulation seem to use Version = 100, so that's what we write. 
   * 
   * We write the color transform byte as 1 if the JPEG color space is 
   * YCbCr, 2 if it's YCCK, 0 otherwise.  Adobe's definition has to do with 
   * whether the encoder performed a transformation, which is pretty useless. 
   */ 
   
  emit_marker(cinfo, M_APP14); 
   
  emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */ 
 
  emit_byte(cinfo, 0x41);	/* Identifier: ASCII "Adobe" */ 
  emit_byte(cinfo, 0x64); 
  emit_byte(cinfo, 0x6F); 
  emit_byte(cinfo, 0x62); 
  emit_byte(cinfo, 0x65); 
  emit_2bytes(cinfo, 100);	/* Version */ 
  emit_2bytes(cinfo, 0);	/* Flags0 */ 
  emit_2bytes(cinfo, 0);	/* Flags1 */ 
  switch (cinfo->jpeg_color_space) { 
  case JCS_YCbCr: 
    emit_byte(cinfo, 1);	/* Color transform = 1 */ 
    break; 
  case JCS_YCCK: 
    emit_byte(cinfo, 2);	/* Color transform = 2 */ 
    break; 
  default: 
    emit_byte(cinfo, 0);	/* Color transform = 0 */ 
    break; 
  } 
} 
 
 
/* 
 * These routines allow writing an arbitrary marker with parameters. 
 * The only intended use is to emit COM or APPn markers after calling 
 * write_file_header and before calling write_frame_header. 
 * Other uses are not guaranteed to produce desirable results. 
 * Counting the parameter bytes properly is the caller's responsibility. 
 */ 
 
METHODDEF(void) 
write_marker_header (j_compress_ptr cinfo, int marker, unsigned int datalen) 
/* Emit an arbitrary marker header */ 
{ 
  if (datalen > (unsigned int) 65533)		/* safety check */ 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  emit_marker(cinfo, (JPEG_MARKER) marker); 
 
  emit_2bytes(cinfo, (int) (datalen + 2));	/* total length */ 
} 
 
METHODDEF(void) 
write_marker_byte (j_compress_ptr cinfo, int val) 
/* Emit one byte of marker parameters following write_marker_header */ 
{ 
  emit_byte(cinfo, val); 
} 
 
 
/* 
 * Write datastream header. 
 * This consists of an SOI and optional APPn markers. 
 * We recommend use of the JFIF marker, but not the Adobe marker, 
 * when using YCbCr or grayscale data.  The JFIF marker should NOT 
 * be used for any other JPEG colorspace.  The Adobe marker is helpful 
 * to distinguish RGB, CMYK, and YCCK colorspaces. 
 * Note that an application can write additional header markers after 
 * jpeg_start_compress returns. 
 */ 
 
METHODDEF(void) 
write_file_header (j_compress_ptr cinfo) 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
 
  emit_marker(cinfo, M_SOI);	/* first the SOI */ 
 
  /* SOI is defined to reset restart interval to 0 */ 
  marker->last_restart_interval = 0; 
 
  if (cinfo->write_JFIF_header)	/* next an optional JFIF APP0 */ 
    emit_jfif_app0(cinfo); 
  if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */ 
    emit_adobe_app14(cinfo); 
} 
 
 
/* 
 * Write frame header. 
 * This consists of DQT and SOFn markers. 
 * Note that we do not emit the SOF until we have emitted the DQT(s). 
 * This avoids compatibility problems with incorrect implementations that 
 * try to error-check the quant table numbers as soon as they see the SOF. 
 */ 
 
METHODDEF(void) 
write_frame_header (j_compress_ptr cinfo) 
{ 
  int ci, prec; 
  boolean is_baseline; 
  jpeg_component_info *compptr; 
   
  /* Emit DQT for each quantization table. 
   * Note that emit_dqt() suppresses any duplicate tables. 
   */ 
  prec = 0; 
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
       ci++, compptr++) { 
    prec += emit_dqt(cinfo, compptr->quant_tbl_no); 
  } 
  /* now prec is nonzero iff there are any 16-bit quant tables. */ 
 
  /* Check for a non-baseline specification. 
   * Note we assume that Huffman table numbers won't be changed later. 
   */ 
  if (cinfo->arith_code || cinfo->progressive_mode || 
      cinfo->data_precision != 8) { 
    is_baseline = FALSE; 
  } else { 
    is_baseline = TRUE; 
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	 ci++, compptr++) { 
      if (compptr->dc_tbl_no > 1 || compptr->ac_tbl_no > 1) 
	is_baseline = FALSE; 
    } 
    if (prec && is_baseline) { 
      is_baseline = FALSE; 
      /* If it's baseline except for quantizer size, warn the user */ 
      TRACEMS(cinfo, 0, JTRC_16BIT_TABLES); 
    } 
  } 
 
  /* Emit the proper SOF marker */ 
  if (cinfo->arith_code) { 
    emit_sof(cinfo, M_SOF9);	/* SOF code for arithmetic coding */ 
  } else { 
    if (cinfo->progressive_mode) 
      emit_sof(cinfo, M_SOF2);	/* SOF code for progressive Huffman */ 
    else if (is_baseline) 
      emit_sof(cinfo, M_SOF0);	/* SOF code for baseline implementation */ 
    else 
      emit_sof(cinfo, M_SOF1);	/* SOF code for non-baseline Huffman file */ 
  } 
} 
 
 
/* 
 * Write scan header. 
 * This consists of DHT or DAC markers, optional DRI, and SOS. 
 * Compressed data will be written following the SOS. 
 */ 
 
METHODDEF(void) 
write_scan_header (j_compress_ptr cinfo) 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
  int i; 
  jpeg_component_info *compptr; 
 
  if (cinfo->arith_code) { 
    /* Emit arith conditioning info.  We may have some duplication 
     * if the file has multiple scans, but it's so small it's hardly 
     * worth worrying about. 
     */ 
    emit_dac(cinfo); 
  } else { 
    /* Emit Huffman tables. 
     * Note that emit_dht() suppresses any duplicate tables. 
     */ 
    for (i = 0; i < cinfo->comps_in_scan; i++) { 
      compptr = cinfo->cur_comp_info[i]; 
      if (cinfo->progressive_mode) { 
	/* Progressive mode: only DC or only AC tables are used in one scan */ 
	if (cinfo->Ss == 0) { 
	  if (cinfo->Ah == 0)	/* DC needs no table for refinement scan */ 
	    emit_dht(cinfo, compptr->dc_tbl_no, FALSE); 
	} else { 
	  emit_dht(cinfo, compptr->ac_tbl_no, TRUE); 
	} 
      } else { 
	/* Sequential mode: need both DC and AC tables */ 
	emit_dht(cinfo, compptr->dc_tbl_no, FALSE); 
	emit_dht(cinfo, compptr->ac_tbl_no, TRUE); 
      } 
    } 
  } 
 
  /* Emit DRI if required --- note that DRI value could change for each scan. 
   * We avoid wasting space with unnecessary DRIs, however. 
   */ 
  if (cinfo->restart_interval != marker->last_restart_interval) { 
    emit_dri(cinfo); 
    marker->last_restart_interval = cinfo->restart_interval; 
  } 
 
  emit_sos(cinfo); 
} 
 
 
/* 
 * Write datastream trailer. 
 */ 
 
METHODDEF(void) 
write_file_trailer (j_compress_ptr cinfo) 
{ 
  emit_marker(cinfo, M_EOI); 
} 
 
 
/* 
 * Write an abbreviated table-specification datastream. 
 * This consists of SOI, DQT and DHT tables, and EOI. 
 * Any table that is defined and not marked sent_table = TRUE will be 
 * emitted.  Note that all tables will be marked sent_table = TRUE at exit. 
 */ 
 
METHODDEF(void) 
write_tables_only (j_compress_ptr cinfo) 
{ 
  int i; 
 
  emit_marker(cinfo, M_SOI); 
 
  for (i = 0; i < NUM_QUANT_TBLS; i++) { 
    if (cinfo->quant_tbl_ptrs[i] != NULL) 
      (void) emit_dqt(cinfo, i); 
  } 
 
  if (! cinfo->arith_code) { 
    for (i = 0; i < NUM_HUFF_TBLS; i++) { 
      if (cinfo->dc_huff_tbl_ptrs[i] != NULL) 
	emit_dht(cinfo, i, FALSE); 
      if (cinfo->ac_huff_tbl_ptrs[i] != NULL) 
	emit_dht(cinfo, i, TRUE); 
    } 
  } 
 
  emit_marker(cinfo, M_EOI); 
} 
 
 
/* 
 * Initialize the marker writer module. 
 */ 
 
GLOBAL(void) 
jinit_marker_writer (j_compress_ptr cinfo) 
{ 
  my_marker_ptr marker; 
 
  /* Create the subobject */ 
  marker = (my_marker_ptr) 
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 
				SIZEOF(my_marker_writer)); 
  cinfo->marker = (struct jpeg_marker_writer *) marker; 
  /* Initialize method pointers */ 
  marker->pub.write_file_header = write_file_header; 
  marker->pub.write_frame_header = write_frame_header; 
  marker->pub.write_scan_header = write_scan_header; 
  marker->pub.write_file_trailer = write_file_trailer; 
  marker->pub.write_tables_only = write_tables_only; 
  marker->pub.write_marker_header = write_marker_header; 
  marker->pub.write_marker_byte = write_marker_byte; 
  /* Initialize private state */ 
  marker->last_restart_interval = 0; 
}