| 1 | /* |
| 2 | * jdapistd.c |
| 3 | * |
| 4 | * Copyright (C) 1994-1996, 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 application interface code for the decompression half |
| 9 | * of the JPEG library. These are the "standard" API routines that are |
| 10 | * used in the normal full-decompression case. They are not used by a |
| 11 | * transcoding-only application. Note that if an application links in |
| 12 | * jpeg_start_decompress, it will end up linking in the entire decompressor. |
| 13 | * We thus must separate this file from jdapimin.c to avoid linking the |
| 14 | * whole decompression library into a transcoder. |
| 15 | */ |
| 16 | |
| 17 | #define JPEG_INTERNALS |
| 18 | #include "jinclude.h" |
| 19 | #include "jpeglib.h" |
| 20 | |
| 21 | |
| 22 | /* Forward declarations */ |
| 23 | LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); |
| 24 | |
| 25 | |
| 26 | /* |
| 27 | * Decompression initialization. |
| 28 | * jpeg_read_header must be completed before calling this. |
| 29 | * |
| 30 | * If a multipass operating mode was selected, this will do all but the |
| 31 | * last pass, and thus may take a great deal of time. |
| 32 | * |
| 33 | * Returns FALSE if suspended. The return value need be inspected only if |
| 34 | * a suspending data source is used. |
| 35 | */ |
| 36 | |
| 37 | GLOBAL(boolean) |
| 38 | jpeg_start_decompress (j_decompress_ptr cinfo) |
| 39 | { |
| 40 | if (cinfo->global_state == DSTATE_READY) { |
| 41 | /* First call: initialize master control, select active modules */ |
| 42 | jinit_master_decompress(cinfo); |
| 43 | if (cinfo->buffered_image) { |
| 44 | /* No more work here; expecting jpeg_start_output next */ |
| 45 | cinfo->global_state = DSTATE_BUFIMAGE; |
| 46 | return TRUE; |
| 47 | } |
| 48 | cinfo->global_state = DSTATE_PRELOAD; |
| 49 | } |
| 50 | if (cinfo->global_state == DSTATE_PRELOAD) { |
| 51 | /* If file has multiple scans, absorb them all into the coef buffer */ |
| 52 | if (cinfo->inputctl->has_multiple_scans) { |
| 53 | #ifdef D_MULTISCAN_FILES_SUPPORTED |
| 54 | for (;;) { |
| 55 | int retcode; |
| 56 | /* Call progress monitor hook if present */ |
| 57 | if (cinfo->progress != NULL) |
| 58 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
| 59 | /* Absorb some more input */ |
| 60 | retcode = (*cinfo->inputctl->consume_input) (cinfo); |
| 61 | if (retcode == JPEG_SUSPENDED) |
| 62 | return FALSE; |
| 63 | if (retcode == JPEG_REACHED_EOI) |
| 64 | break; |
| 65 | /* Advance progress counter if appropriate */ |
| 66 | if (cinfo->progress != NULL && |
| 67 | (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { |
| 68 | if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { |
| 69 | /* jdmaster underestimated number of scans; ratchet up one scan */ |
| 70 | cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; |
| 71 | } |
| 72 | } |
| 73 | } |
| 74 | #else |
| 75 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
| 76 | #endif /* D_MULTISCAN_FILES_SUPPORTED */ |
| 77 | } |
| 78 | cinfo->output_scan_number = cinfo->input_scan_number; |
| 79 | } else if (cinfo->global_state != DSTATE_PRESCAN) |
| 80 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| 81 | /* Perform any dummy output passes, and set up for the final pass */ |
| 82 | return output_pass_setup(cinfo); |
| 83 | } |
| 84 | |
| 85 | |
| 86 | /* |
| 87 | * Set up for an output pass, and perform any dummy pass(es) needed. |
| 88 | * Common subroutine for jpeg_start_decompress and jpeg_start_output. |
| 89 | * Entry: global_state = DSTATE_PRESCAN only if previously suspended. |
| 90 | * Exit: If done, returns TRUE and sets global_state for proper output mode. |
| 91 | * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. |
| 92 | */ |
| 93 | |
| 94 | LOCAL(boolean) |
| 95 | output_pass_setup (j_decompress_ptr cinfo) |
| 96 | { |
| 97 | if (cinfo->global_state != DSTATE_PRESCAN) { |
| 98 | /* First call: do pass setup */ |
| 99 | (*cinfo->master->prepare_for_output_pass) (cinfo); |
| 100 | cinfo->output_scanline = 0; |
| 101 | cinfo->global_state = DSTATE_PRESCAN; |
| 102 | } |
| 103 | /* Loop over any required dummy passes */ |
| 104 | while (cinfo->master->is_dummy_pass) { |
| 105 | #ifdef QUANT_2PASS_SUPPORTED |
| 106 | /* Crank through the dummy pass */ |
| 107 | while (cinfo->output_scanline < cinfo->output_height) { |
| 108 | JDIMENSION last_scanline; |
| 109 | /* Call progress monitor hook if present */ |
| 110 | if (cinfo->progress != NULL) { |
| 111 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
| 112 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
| 113 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
| 114 | } |
| 115 | /* Process some data */ |
| 116 | last_scanline = cinfo->output_scanline; |
| 117 | (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, |
| 118 | &cinfo->output_scanline, (JDIMENSION) 0); |
| 119 | if (cinfo->output_scanline == last_scanline) |
| 120 | return FALSE; /* No progress made, must suspend */ |
| 121 | } |
| 122 | /* Finish up dummy pass, and set up for another one */ |
| 123 | (*cinfo->master->finish_output_pass) (cinfo); |
| 124 | (*cinfo->master->prepare_for_output_pass) (cinfo); |
| 125 | cinfo->output_scanline = 0; |
| 126 | #else |
| 127 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
| 128 | #endif /* QUANT_2PASS_SUPPORTED */ |
| 129 | } |
| 130 | /* Ready for application to drive output pass through |
| 131 | * jpeg_read_scanlines or jpeg_read_raw_data. |
| 132 | */ |
| 133 | cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; |
| 134 | return TRUE; |
| 135 | } |
| 136 | |
| 137 | |
| 138 | /* |
| 139 | * Read some scanlines of data from the JPEG decompressor. |
| 140 | * |
| 141 | * The return value will be the number of lines actually read. |
| 142 | * This may be less than the number requested in several cases, |
| 143 | * including bottom of image, data source suspension, and operating |
| 144 | * modes that emit multiple scanlines at a time. |
| 145 | * |
| 146 | * Note: we warn about excess calls to jpeg_read_scanlines() since |
| 147 | * this likely signals an application programmer error. However, |
| 148 | * an oversize buffer (max_lines > scanlines remaining) is not an error. |
| 149 | */ |
| 150 | |
| 151 | GLOBAL(JDIMENSION) |
| 152 | jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines, |
| 153 | JDIMENSION max_lines) |
| 154 | { |
| 155 | JDIMENSION row_ctr; |
| 156 | |
| 157 | if (cinfo->global_state != DSTATE_SCANNING) |
| 158 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| 159 | if (cinfo->output_scanline >= cinfo->output_height) { |
| 160 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
| 161 | return 0; |
| 162 | } |
| 163 | |
| 164 | /* Call progress monitor hook if present */ |
| 165 | if (cinfo->progress != NULL) { |
| 166 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
| 167 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
| 168 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
| 169 | } |
| 170 | |
| 171 | /* Process some data */ |
| 172 | row_ctr = 0; |
| 173 | (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); |
| 174 | cinfo->output_scanline += row_ctr; |
| 175 | return row_ctr; |
| 176 | } |
| 177 | |
| 178 | |
| 179 | /* |
| 180 | * Alternate entry point to read raw data. |
| 181 | * Processes exactly one iMCU row per call, unless suspended. |
| 182 | */ |
| 183 | |
| 184 | GLOBAL(JDIMENSION) |
| 185 | jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, |
| 186 | JDIMENSION max_lines) |
| 187 | { |
| 188 | JDIMENSION lines_per_iMCU_row; |
| 189 | |
| 190 | if (cinfo->global_state != DSTATE_RAW_OK) |
| 191 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| 192 | if (cinfo->output_scanline >= cinfo->output_height) { |
| 193 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
| 194 | return 0; |
| 195 | } |
| 196 | |
| 197 | /* Call progress monitor hook if present */ |
| 198 | if (cinfo->progress != NULL) { |
| 199 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
| 200 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
| 201 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
| 202 | } |
| 203 | |
| 204 | /* Verify that at least one iMCU row can be returned. */ |
| 205 | lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size; |
| 206 | if (max_lines < lines_per_iMCU_row) |
| 207 | ERREXIT(cinfo, JERR_BUFFER_SIZE); |
| 208 | |
| 209 | /* Decompress directly into user's buffer. */ |
| 210 | if (! (*cinfo->coef->decompress_data) (cinfo, data)) |
| 211 | return 0; /* suspension forced, can do nothing more */ |
| 212 | |
| 213 | /* OK, we processed one iMCU row. */ |
| 214 | cinfo->output_scanline += lines_per_iMCU_row; |
| 215 | return lines_per_iMCU_row; |
| 216 | } |
| 217 | |
| 218 | |
| 219 | /* Additional entry points for buffered-image mode. */ |
| 220 | |
| 221 | #ifdef D_MULTISCAN_FILES_SUPPORTED |
| 222 | |
| 223 | /* |
| 224 | * Initialize for an output pass in buffered-image mode. |
| 225 | */ |
| 226 | |
| 227 | GLOBAL(boolean) |
| 228 | jpeg_start_output (j_decompress_ptr cinfo, int scan_number) |
| 229 | { |
| 230 | if (cinfo->global_state != DSTATE_BUFIMAGE && |
| 231 | cinfo->global_state != DSTATE_PRESCAN) |
| 232 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| 233 | /* Limit scan number to valid range */ |
| 234 | if (scan_number <= 0) |
| 235 | scan_number = 1; |
| 236 | if (cinfo->inputctl->eoi_reached && |
| 237 | scan_number > cinfo->input_scan_number) |
| 238 | scan_number = cinfo->input_scan_number; |
| 239 | cinfo->output_scan_number = scan_number; |
| 240 | /* Perform any dummy output passes, and set up for the real pass */ |
| 241 | return output_pass_setup(cinfo); |
| 242 | } |
| 243 | |
| 244 | |
| 245 | /* |
| 246 | * Finish up after an output pass in buffered-image mode. |
| 247 | * |
| 248 | * Returns FALSE if suspended. The return value need be inspected only if |
| 249 | * a suspending data source is used. |
| 250 | */ |
| 251 | |
| 252 | GLOBAL(boolean) |
| 253 | jpeg_finish_output (j_decompress_ptr cinfo) |
| 254 | { |
| 255 | if ((cinfo->global_state == DSTATE_SCANNING || |
| 256 | cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { |
| 257 | /* Terminate this pass. */ |
| 258 | /* We do not require the whole pass to have been completed. */ |
| 259 | (*cinfo->master->finish_output_pass) (cinfo); |
| 260 | cinfo->global_state = DSTATE_BUFPOST; |
| 261 | } else if (cinfo->global_state != DSTATE_BUFPOST) { |
| 262 | /* BUFPOST = repeat call after a suspension, anything else is error */ |
| 263 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| 264 | } |
| 265 | /* Read markers looking for SOS or EOI */ |
| 266 | while (cinfo->input_scan_number <= cinfo->output_scan_number && |
| 267 | ! cinfo->inputctl->eoi_reached) { |
| 268 | if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) |
| 269 | return FALSE; /* Suspend, come back later */ |
| 270 | } |
| 271 | cinfo->global_state = DSTATE_BUFIMAGE; |
| 272 | return TRUE; |
| 273 | } |
| 274 | |
| 275 | #endif /* D_MULTISCAN_FILES_SUPPORTED */ |