www.pudn.com > imgport.rar > jcinit.c, change:2008-11-05,size:2421b


/* 
 * jcinit.c 
 * 
 * Copyright (C) 1991-1997, 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 initialization logic for the JPEG compressor. 
 * This routine is in charge of selecting the modules to be executed and 
 * making an initialization call to each one. 
 * 
 * Logically, this code belongs in jcmaster.c.  It's split out because 
 * linking this routine implies linking the entire compression library. 
 * For a transcoding-only application, we want to be able to use jcmaster.c 
 * without linking in the whole library. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
/* 
 * Master selection of compression modules. 
 * This is done once at the start of processing an image.  We determine 
 * which modules will be used and give them appropriate initialization calls. 
 */ 
 
GLOBAL(void) 
jinit_compress_master (j_compress_ptr cinfo) 
{ 
  /* Initialize master control (includes parameter checking/processing) */ 
  jinit_c_master_control(cinfo, FALSE /* full compression */); 
 
  /* Preprocessing */ 
  if (! cinfo->raw_data_in) { 
    jinit_color_converter(cinfo); 
    jinit_downsampler(cinfo); 
    jinit_c_prep_controller(cinfo, FALSE /* never need full buffer here */); 
  } 
  /* Forward DCT */ 
  jinit_forward_dct(cinfo); 
  /* Entropy encoding: either Huffman or arithmetic coding. */ 
  if (cinfo->arith_code) { 
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL); 
  } else { 
    if (cinfo->progressive_mode) { 
#ifdef C_PROGRESSIVE_SUPPORTED 
      jinit_phuff_encoder(cinfo); 
#else 
      ERREXIT(cinfo, JERR_NOT_COMPILED); 
#endif 
    } else 
      jinit_huff_encoder(cinfo); 
  } 
 
  /* Need a full-image coefficient buffer in any multi-pass mode. */ 
  jinit_c_coef_controller(cinfo, 
		(boolean) (cinfo->num_scans > 1 || cinfo->optimize_coding)); 
  jinit_c_main_controller(cinfo, FALSE /* never need full buffer here */); 
 
  jinit_marker_writer(cinfo); 
 
  /* We can now tell the memory manager to allocate virtual arrays. */ 
  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo); 
 
  /* Write the datastream header (SOI) immediately. 
   * Frame and scan headers are postponed till later. 
   * This lets application insert special markers after the SOI. 
   */ 
  (*cinfo->marker->write_file_header) (cinfo); 
}