www.pudn.com > imgport.rar > jcapimin.c, change:2008-11-05,size:9401b


/* 
 * jcapimin.c 
 * 
 * Copyright (C) 1994-1998, 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 application interface code for the compression half 
 * of the JPEG library.  These are the "minimum" API routines that may be 
 * needed in either the normal full-compression case or the transcoding-only 
 * case. 
 * 
 * Most of the routines intended to be called directly by an application 
 * are in this file or in jcapistd.c.  But also see jcparam.c for 
 * parameter-setup helper routines, jcomapi.c for routines shared by 
 * compression and decompression, and jctrans.c for the transcoding case. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
/* 
 * Initialization of a JPEG compression object. 
 * The error manager must already be set up (in case memory manager fails). 
 */ 
 
GLOBAL(void) 
jpeg_CreateCompress (j_compress_ptr cinfo, int version, size_t structsize) 
{ 
  int i; 
 
  /* Guard against version mismatches between library and caller. */ 
  cinfo->mem = NULL;		/* so jpeg_destroy knows mem mgr not called */ 
  if (version != JPEG_LIB_VERSION) 
    ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version); 
  if (structsize != SIZEOF(struct jpeg_compress_struct)) 
    ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,  
	     (int) SIZEOF(struct jpeg_compress_struct), (int) structsize); 
 
  /* For debugging purposes, we zero the whole master structure. 
   * But the application has already set the err pointer, and may have set 
   * client_data, so we have to save and restore those fields. 
   * Note: if application hasn't set client_data, tools like Purify may 
   * complain here. 
   */ 
  { 
    struct jpeg_error_mgr * err = cinfo->err; 
    void * client_data = cinfo->client_data; /* ignore Purify complaint here */ 
    MEMZERO(cinfo, SIZEOF(struct jpeg_compress_struct)); 
    cinfo->err = err; 
    cinfo->client_data = client_data; 
  } 
  cinfo->is_decompressor = FALSE; 
 
  /* Initialize a memory manager instance for this object */ 
  jinit_memory_mgr((j_common_ptr) cinfo); 
 
  /* Zero out pointers to permanent structures. */ 
  cinfo->progress = NULL; 
  cinfo->dest = NULL; 
 
  cinfo->comp_info = NULL; 
 
  for (i = 0; i < NUM_QUANT_TBLS; i++) 
    cinfo->quant_tbl_ptrs[i] = NULL; 
 
  for (i = 0; i < NUM_HUFF_TBLS; i++) { 
    cinfo->dc_huff_tbl_ptrs[i] = NULL; 
    cinfo->ac_huff_tbl_ptrs[i] = NULL; 
  } 
 
  cinfo->script_space = NULL; 
 
  cinfo->input_gamma = 1.0;	/* in case application forgets */ 
 
  /* OK, I'm ready */ 
  cinfo->global_state = CSTATE_START; 
} 
 
 
/* 
 * Destruction of a JPEG compression object 
 */ 
 
GLOBAL(void) 
jpeg_destroy_compress (j_compress_ptr cinfo) 
{ 
  jpeg_destroy((j_common_ptr) cinfo); /* use common routine */ 
} 
 
 
/* 
 * Abort processing of a JPEG compression operation, 
 * but don't destroy the object itself. 
 */ 
 
GLOBAL(void) 
jpeg_abort_compress (j_compress_ptr cinfo) 
{ 
  jpeg_abort((j_common_ptr) cinfo); /* use common routine */ 
} 
 
 
/* 
 * Forcibly suppress or un-suppress all quantization and Huffman tables. 
 * Marks all currently defined tables as already written (if suppress) 
 * or not written (if !suppress).  This will control whether they get emitted 
 * by a subsequent jpeg_start_compress call. 
 * 
 * This routine is exported for use by applications that want to produce 
 * abbreviated JPEG datastreams.  It logically belongs in jcparam.c, but 
 * since it is called by jpeg_start_compress, we put it here --- otherwise 
 * jcparam.o would be linked whether the application used it or not. 
 */ 
 
GLOBAL(void) 
jpeg_suppress_tables (j_compress_ptr cinfo, boolean suppress) 
{ 
  int i; 
  JQUANT_TBL * qtbl; 
  JHUFF_TBL * htbl; 
 
  for (i = 0; i < NUM_QUANT_TBLS; i++) { 
    if ((qtbl = cinfo->quant_tbl_ptrs[i]) != NULL) 
      qtbl->sent_table = suppress; 
  } 
 
  for (i = 0; i < NUM_HUFF_TBLS; i++) { 
    if ((htbl = cinfo->dc_huff_tbl_ptrs[i]) != NULL) 
      htbl->sent_table = suppress; 
    if ((htbl = cinfo->ac_huff_tbl_ptrs[i]) != NULL) 
      htbl->sent_table = suppress; 
  } 
} 
 
 
/* 
 * Finish JPEG compression. 
 * 
 * If a multipass operating mode was selected, this may do a great deal of 
 * work including most of the actual output. 
 */ 
 
GLOBAL(void) 
jpeg_finish_compress (j_compress_ptr cinfo) 
{ 
  JDIMENSION iMCU_row; 
 
  if (cinfo->global_state == CSTATE_SCANNING || 
      cinfo->global_state == CSTATE_RAW_OK) { 
    /* Terminate first pass */ 
    if (cinfo->next_scanline < cinfo->image_height) 
      ERREXIT(cinfo, JERR_TOO_LITTLE_DATA); 
    (*cinfo->master->finish_pass) (cinfo); 
  } else if (cinfo->global_state != CSTATE_WRCOEFS) 
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 
  /* Perform any remaining passes */ 
  while (! cinfo->master->is_last_pass) { 
    (*cinfo->master->prepare_for_pass) (cinfo); 
    for (iMCU_row = 0; iMCU_row < cinfo->total_iMCU_rows; iMCU_row++) { 
      if (cinfo->progress != NULL) { 
	cinfo->progress->pass_counter = (long) iMCU_row; 
	cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows; 
	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 
      } 
      /* We bypass the main controller and invoke coef controller directly; 
       * all work is being done from the coefficient buffer. 
       */ 
      if (! (*cinfo->coef->compress_data) (cinfo, (JSAMPIMAGE) NULL)) 
	ERREXIT(cinfo, JERR_CANT_SUSPEND); 
    } 
    (*cinfo->master->finish_pass) (cinfo); 
  } 
  /* Write EOI, do final cleanup */ 
  (*cinfo->marker->write_file_trailer) (cinfo); 
  (*cinfo->dest->term_destination) (cinfo); 
  /* We can use jpeg_abort to release memory and reset global_state */ 
  jpeg_abort((j_common_ptr) cinfo); 
} 
 
 
/* 
 * Write a special marker. 
 * This is only recommended for writing COM or APPn markers. 
 * Must be called after jpeg_start_compress() and before 
 * first call to jpeg_write_scanlines() or jpeg_write_raw_data(). 
 */ 
 
GLOBAL(void) 
jpeg_write_marker (j_compress_ptr cinfo, int marker, 
		   const JOCTET *dataptr, unsigned int datalen) 
{ 
  JMETHOD(void, write_marker_byte, (j_compress_ptr info, int val)); 
 
  if (cinfo->next_scanline != 0 || 
      (cinfo->global_state != CSTATE_SCANNING && 
       cinfo->global_state != CSTATE_RAW_OK && 
       cinfo->global_state != CSTATE_WRCOEFS)) 
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 
 
  (*cinfo->marker->write_marker_header) (cinfo, marker, datalen); 
  write_marker_byte = cinfo->marker->write_marker_byte;	/* copy for speed */ 
  while (datalen--) { 
    (*write_marker_byte) (cinfo, *dataptr); 
    dataptr++; 
  } 
} 
 
/* Same, but piecemeal. */ 
 
GLOBAL(void) 
jpeg_write_m_header (j_compress_ptr cinfo, int marker, unsigned int datalen) 
{ 
  if (cinfo->next_scanline != 0 || 
      (cinfo->global_state != CSTATE_SCANNING && 
       cinfo->global_state != CSTATE_RAW_OK && 
       cinfo->global_state != CSTATE_WRCOEFS)) 
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 
 
  (*cinfo->marker->write_marker_header) (cinfo, marker, datalen); 
} 
 
GLOBAL(void) 
jpeg_write_m_byte (j_compress_ptr cinfo, int val) 
{ 
  (*cinfo->marker->write_marker_byte) (cinfo, val); 
} 
 
 
/* 
 * Alternate compression function: just write an abbreviated table file. 
 * Before calling this, all parameters and a data destination must be set up. 
 * 
 * To produce a pair of files containing abbreviated tables and abbreviated 
 * image data, one would proceed as follows: 
 * 
 *		initialize JPEG object 
 *		set JPEG parameters 
 *		set destination to table file 
 *		jpeg_write_tables(cinfo); 
 *		set destination to image file 
 *		jpeg_start_compress(cinfo, FALSE); 
 *		write data... 
 *		jpeg_finish_compress(cinfo); 
 * 
 * jpeg_write_tables has the side effect of marking all tables written 
 * (same as jpeg_suppress_tables(..., TRUE)).  Thus a subsequent start_compress 
 * will not re-emit the tables unless it is passed write_all_tables=TRUE. 
 */ 
 
GLOBAL(void) 
jpeg_write_tables (j_compress_ptr cinfo) 
{ 
  if (cinfo->global_state != CSTATE_START) 
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 
 
  /* (Re)initialize error mgr and destination modules */ 
  (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 
  (*cinfo->dest->init_destination) (cinfo); 
  /* Initialize the marker writer ... bit of a crock to do it here. */ 
  jinit_marker_writer(cinfo); 
  /* Write them tables! */ 
  (*cinfo->marker->write_tables_only) (cinfo); 
  /* And clean up. */ 
  (*cinfo->dest->term_destination) (cinfo); 
  /* 
   * In library releases up through v6a, we called jpeg_abort() here to free 
   * any working memory allocated by the destination manager and marker 
   * writer.  Some applications had a problem with that: they allocated space 
   * of their own from the library memory manager, and didn't want it to go 
   * away during write_tables.  So now we do nothing.  This will cause a 
   * memory leak if an app calls write_tables repeatedly without doing a full 
   * compression cycle or otherwise resetting the JPEG object.  However, that 
   * seems less bad than unexpectedly freeing memory in the normal case. 
   * An app that prefers the old behavior can call jpeg_abort for itself after 
   * each call to jpeg_write_tables(). 
   */ 
}