jcinit.cpp (2500B)
1 /* 2 * jcinit.c 3 * 4 * Copyright (C) 1991-1995, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains initialization logic for the JPEG compressor. 9 * This routine is in charge of selecting the modules to be executed and 10 * making an initialization call to each one. 11 * 12 * Logically, this code belongs in jcmaster.c. It's split out because 13 * linking this routine implies linking the entire compression library. 14 * For a transcoding-only application, we want to be able to use jcmaster.c 15 * without linking in the whole library. 16 */ 17 18 #define JPEG_INTERNALS 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 22 23 /* 24 * Master selection of compression modules. 25 * This is done once at the start of processing an image. We determine 26 * which modules will be used and give them appropriate initialization calls. 27 */ 28 29 GLOBAL void 30 jinit_compress_master( j_compress_ptr cinfo ) { 31 /* Initialize master control (includes parameter checking/processing) */ 32 jinit_c_master_control( cinfo, FALSE /* full compression */ ); 33 34 /* Preprocessing */ 35 if ( !cinfo->raw_data_in ) { 36 jinit_color_converter( cinfo ); 37 jinit_downsampler( cinfo ); 38 jinit_c_prep_controller( cinfo, FALSE /* never need full buffer here */ ); 39 } 40 /* Forward DCT */ 41 jinit_forward_dct( cinfo ); 42 /* Entropy encoding: either Huffman or arithmetic coding. */ 43 if ( cinfo->arith_code ) { 44 ERREXIT( cinfo, JERR_ARITH_NOTIMPL ); 45 } else { 46 if ( cinfo->progressive_mode ) { 47 #ifdef C_PROGRESSIVE_SUPPORTED 48 jinit_phuff_encoder( cinfo ); 49 #else 50 ERREXIT( cinfo, JERR_NOT_COMPILED ); 51 #endif 52 } else { 53 jinit_huff_encoder( cinfo ); 54 } 55 } 56 57 /* Need a full-image coefficient buffer in any multi-pass mode. */ 58 jinit_c_coef_controller( cinfo, 59 ( cinfo->num_scans > 1 || cinfo->optimize_coding ) ); 60 jinit_c_main_controller( cinfo, FALSE /* never need full buffer here */ ); 61 62 jinit_marker_writer( cinfo ); 63 64 /* We can now tell the memory manager to allocate virtual arrays. */ 65 ( *cinfo->mem->realize_virt_arrays )( (j_common_ptr) cinfo ); 66 67 /* Write the datastream header (SOI) immediately. 68 * Frame and scan headers are postponed till later. 69 * This lets application insert special markers after the SOI. 70 */ 71 ( *cinfo->marker->write_file_header )( cinfo ); 72 }