1 /* 2 * jcinit.c 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * Modified 2003-2013 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains initialization logic for the JPEG compressor. 10 * This routine is in charge of selecting the modules to be executed and 11 * making an initialization call to each one. 12 * 13 * Logically, this code belongs in jcmaster.c. It's split out because 14 * linking this routine implies linking the entire compression library. 15 * For a transcoding-only application, we want to be able to use jcmaster.c 16 * without linking in the whole library. 17 */ 18 19 #define JPEG_INTERNALS 20 #include "jinclude.h" 21 #include "jpeglib.h" 22 23 24 /* 25 * Master selection of compression modules. 26 * This is done once at the start of processing an image. We determine 27 * which modules will be used and give them appropriate initialization calls. 28 */ 29 30 GLOBAL(void) 31 jinit_compress_master (j_compress_ptr cinfo) 32 { 33 long samplesperrow; 34 JDIMENSION jd_samplesperrow; 35 36 /* For now, precision must match compiled-in value... */ 37 if (cinfo->data_precision != BITS_IN_JSAMPLE) 38 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 39 40 /* Sanity check on image dimensions */ 41 if (cinfo->image_height <= 0 || cinfo->image_width <= 0 || 42 cinfo->input_components <= 0) 43 ERREXIT(cinfo, JERR_EMPTY_IMAGE); 44 45 /* Width of an input scanline must be representable as JDIMENSION. */ 46 samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components; 47 jd_samplesperrow = (JDIMENSION) samplesperrow; 48 if ((long) jd_samplesperrow != samplesperrow) 49 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW); 50 51 /* Initialize master control (includes parameter checking/processing) */ 52 jinit_c_master_control(cinfo, FALSE /* full compression */); 53 54 /* Preprocessing */ 55 if (! cinfo->raw_data_in) { 56 jinit_color_converter(cinfo); 57 jinit_downsampler(cinfo); 58 jinit_c_prep_controller(cinfo, FALSE /* never need full buffer here */); 59 } 60 /* Forward DCT */ 61 jinit_forward_dct(cinfo); 62 /* Entropy encoding: either Huffman or arithmetic coding. */ 63 if (cinfo->arith_code) 64 jinit_arith_encoder(cinfo); 65 else { 66 jinit_huff_encoder(cinfo); 67 } 68 69 /* Need a full-image coefficient buffer in any multi-pass mode. */ 70 jinit_c_coef_controller(cinfo, 71 (boolean) (cinfo->num_scans > 1 || cinfo->optimize_coding)); 72 jinit_c_main_controller(cinfo, FALSE /* never need full buffer here */); 73 74 jinit_marker_writer(cinfo); 75 76 /* We can now tell the memory manager to allocate virtual arrays. */ 77 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo); 78 79 /* Write the datastream header (SOI) immediately. 80 * Frame and scan headers are postponed till later. 81 * This lets application insert special markers after the SOI. 82 */ 83 (*cinfo->marker->write_file_header) (cinfo); 84 } 85