4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1998, Thomas G. Lane.
6 * Lossless JPEG Modifications:
7 * Copyright (C) 1999, Ken Murchison.
8 * libjpeg-turbo Modifications:
9 * Copyright (C) 2016, 2022, D. R. Commander.
10 * For conditions of distribution and use, see the accompanying README.ijg
13 * This file contains application interface code for the decompression half
14 * of the JPEG library. These are the "minimum" API routines that may be
15 * needed in either the normal full-decompression case or the
16 * transcoding-only case.
18 * Most of the routines intended to be called directly by an application
19 * are in this file or in jdapistd.c. But also see jcomapi.c for routines
20 * shared by compression and decompression, and jdtrans.c for the transcoding
24 #define JPEG_INTERNALS
31 * Initialization of a JPEG decompression object.
32 * The error manager must already be set up (in case memory manager fails).
36 jpeg_CreateDecompress(j_decompress_ptr cinfo, int version, size_t structsize)
40 /* Guard against version mismatches between library and caller. */
41 cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */
42 if (version != JPEG_LIB_VERSION)
43 ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
44 if (structsize != sizeof(struct jpeg_decompress_struct))
45 ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
46 (int)sizeof(struct jpeg_decompress_struct), (int)structsize);
48 /* For debugging purposes, we zero the whole master structure.
49 * But the application has already set the err pointer, and may have set
50 * client_data, so we have to save and restore those fields.
51 * Note: if application hasn't set client_data, tools like Purify may
55 struct jpeg_error_mgr *err = cinfo->err;
56 void *client_data = cinfo->client_data; /* ignore Purify complaint here */
57 memset(cinfo, 0, sizeof(struct jpeg_decompress_struct));
59 cinfo->client_data = client_data;
61 cinfo->is_decompressor = TRUE;
63 /* Initialize a memory manager instance for this object */
64 jinit_memory_mgr((j_common_ptr)cinfo);
66 /* Zero out pointers to permanent structures. */
67 cinfo->progress = NULL;
70 for (i = 0; i < NUM_QUANT_TBLS; i++)
71 cinfo->quant_tbl_ptrs[i] = NULL;
73 for (i = 0; i < NUM_HUFF_TBLS; i++) {
74 cinfo->dc_huff_tbl_ptrs[i] = NULL;
75 cinfo->ac_huff_tbl_ptrs[i] = NULL;
78 /* Initialize marker processor so application can override methods
79 * for COM, APPn markers before calling jpeg_read_header.
81 cinfo->marker_list = NULL;
82 jinit_marker_reader(cinfo);
84 /* And initialize the overall input controller. */
85 jinit_input_controller(cinfo);
87 cinfo->data_precision = BITS_IN_JSAMPLE;
90 cinfo->global_state = DSTATE_START;
92 /* The master struct is used to store extension parameters, so we allocate it
95 cinfo->master = (struct jpeg_decomp_master *)
96 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
97 sizeof(my_decomp_master));
98 memset(cinfo->master, 0, sizeof(my_decomp_master));
103 * Destruction of a JPEG decompression object
107 jpeg_destroy_decompress(j_decompress_ptr cinfo)
109 jpeg_destroy((j_common_ptr)cinfo); /* use common routine */
114 * Abort processing of a JPEG decompression operation,
115 * but don't destroy the object itself.
119 jpeg_abort_decompress(j_decompress_ptr cinfo)
121 jpeg_abort((j_common_ptr)cinfo); /* use common routine */
126 * Set default decompression parameters.
130 default_decompress_parms(j_decompress_ptr cinfo)
132 /* Guess the input colorspace, and set output colorspace accordingly. */
133 /* (Wish JPEG committee had provided a real way to specify this...) */
134 /* Note application may override our guesses. */
135 switch (cinfo->num_components) {
137 cinfo->jpeg_color_space = JCS_GRAYSCALE;
138 cinfo->out_color_space = JCS_GRAYSCALE;
142 if (cinfo->saw_JFIF_marker) {
143 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
144 } else if (cinfo->saw_Adobe_marker) {
145 switch (cinfo->Adobe_transform) {
147 cinfo->jpeg_color_space = JCS_RGB;
150 cinfo->jpeg_color_space = JCS_YCbCr;
153 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
154 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
158 /* Saw no special markers, try to guess from the component IDs */
159 int cid0 = cinfo->comp_info[0].component_id;
160 int cid1 = cinfo->comp_info[1].component_id;
161 int cid2 = cinfo->comp_info[2].component_id;
163 if (cid0 == 1 && cid1 == 2 && cid2 == 3)
164 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
165 else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
166 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
168 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
169 if (cinfo->master->lossless)
170 cinfo->jpeg_color_space = JCS_RGB; /* assume it's RGB */
172 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
175 /* Always guess RGB is proper output colorspace. */
176 cinfo->out_color_space = JCS_RGB;
180 if (cinfo->saw_Adobe_marker) {
181 switch (cinfo->Adobe_transform) {
183 cinfo->jpeg_color_space = JCS_CMYK;
186 cinfo->jpeg_color_space = JCS_YCCK;
189 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
190 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
194 /* No special markers, assume straight CMYK. */
195 cinfo->jpeg_color_space = JCS_CMYK;
197 cinfo->out_color_space = JCS_CMYK;
201 cinfo->jpeg_color_space = JCS_UNKNOWN;
202 cinfo->out_color_space = JCS_UNKNOWN;
206 /* Set defaults for other decompression parameters. */
207 cinfo->scale_num = 1; /* 1:1 scaling */
208 cinfo->scale_denom = 1;
209 cinfo->output_gamma = 1.0;
210 cinfo->buffered_image = FALSE;
211 cinfo->raw_data_out = FALSE;
212 cinfo->dct_method = JDCT_DEFAULT;
213 cinfo->do_fancy_upsampling = TRUE;
214 cinfo->do_block_smoothing = TRUE;
215 cinfo->quantize_colors = FALSE;
216 /* We set these in case application only sets quantize_colors. */
217 cinfo->dither_mode = JDITHER_FS;
218 #ifdef QUANT_2PASS_SUPPORTED
219 cinfo->two_pass_quantize = TRUE;
221 cinfo->two_pass_quantize = FALSE;
223 cinfo->desired_number_of_colors = 256;
224 cinfo->colormap = NULL;
225 /* Initialize for no mode change in buffered-image mode. */
226 cinfo->enable_1pass_quant = FALSE;
227 cinfo->enable_external_quant = FALSE;
228 cinfo->enable_2pass_quant = FALSE;
233 * Decompression startup: read start of JPEG datastream to see what's there.
234 * Need only initialize JPEG object and supply a data source before calling.
236 * This routine will read as far as the first SOS marker (ie, actual start of
237 * compressed data), and will save all tables and parameters in the JPEG
238 * object. It will also initialize the decompression parameters to default
239 * values, and finally return JPEG_HEADER_OK. On return, the application may
240 * adjust the decompression parameters and then call jpeg_start_decompress.
241 * (Or, if the application only wanted to determine the image parameters,
242 * the data need not be decompressed. In that case, call jpeg_abort or
243 * jpeg_destroy to release any temporary space.)
244 * If an abbreviated (tables only) datastream is presented, the routine will
245 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
246 * re-use the JPEG object to read the abbreviated image datastream(s).
247 * It is unnecessary (but OK) to call jpeg_abort in this case.
248 * The JPEG_SUSPENDED return code only occurs if the data source module
249 * requests suspension of the decompressor. In this case the application
250 * should load more source data and then re-call jpeg_read_header to resume
252 * If a non-suspending data source is used and require_image is TRUE, then the
253 * return code need not be inspected since only JPEG_HEADER_OK is possible.
255 * This routine is now just a front end to jpeg_consume_input, with some
256 * extra error checking.
260 jpeg_read_header(j_decompress_ptr cinfo, boolean require_image)
264 if (cinfo->global_state != DSTATE_START &&
265 cinfo->global_state != DSTATE_INHEADER)
266 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
268 retcode = jpeg_consume_input(cinfo);
271 case JPEG_REACHED_SOS:
272 retcode = JPEG_HEADER_OK;
274 case JPEG_REACHED_EOI:
275 if (require_image) /* Complain if application wanted an image */
276 ERREXIT(cinfo, JERR_NO_IMAGE);
277 /* Reset to start state; it would be safer to require the application to
278 * call jpeg_abort, but we can't change it now for compatibility reasons.
279 * A side effect is to free any temporary memory (there shouldn't be any).
281 jpeg_abort((j_common_ptr)cinfo); /* sets state = DSTATE_START */
282 retcode = JPEG_HEADER_TABLES_ONLY;
294 * Consume data in advance of what the decompressor requires.
295 * This can be called at any time once the decompressor object has
296 * been created and a data source has been set up.
298 * This routine is essentially a state machine that handles a couple
299 * of critical state-transition actions, namely initial setup and
300 * transition from header scanning to ready-for-start_decompress.
301 * All the actual input is done via the input controller's consume_input
306 jpeg_consume_input(j_decompress_ptr cinfo)
308 int retcode = JPEG_SUSPENDED;
310 /* NB: every possible DSTATE value should be listed in this switch */
311 switch (cinfo->global_state) {
313 /* Start-of-datastream actions: reset appropriate modules */
314 (*cinfo->inputctl->reset_input_controller) (cinfo);
315 /* Initialize application's data source module */
316 (*cinfo->src->init_source) (cinfo);
317 cinfo->global_state = DSTATE_INHEADER;
318 FALLTHROUGH /*FALLTHROUGH*/
319 case DSTATE_INHEADER:
320 retcode = (*cinfo->inputctl->consume_input) (cinfo);
321 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
322 /* Set up default parameters based on header data */
323 default_decompress_parms(cinfo);
324 /* Set global state: ready for start_decompress */
325 cinfo->global_state = DSTATE_READY;
329 /* Can't advance past first SOS until start_decompress is called */
330 retcode = JPEG_REACHED_SOS;
334 case DSTATE_SCANNING:
336 case DSTATE_BUFIMAGE:
338 case DSTATE_STOPPING:
339 retcode = (*cinfo->inputctl->consume_input) (cinfo);
342 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
349 * Have we finished reading the input file?
353 jpeg_input_complete(j_decompress_ptr cinfo)
355 /* Check for valid jpeg object */
356 if (cinfo->global_state < DSTATE_START ||
357 cinfo->global_state > DSTATE_STOPPING)
358 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
359 return cinfo->inputctl->eoi_reached;
364 * Is there more than one scan?
368 jpeg_has_multiple_scans(j_decompress_ptr cinfo)
370 /* Only valid after jpeg_read_header completes */
371 if (cinfo->global_state < DSTATE_READY ||
372 cinfo->global_state > DSTATE_STOPPING)
373 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
374 return cinfo->inputctl->has_multiple_scans;
379 * Finish JPEG decompression.
381 * This will normally just verify the file trailer and release temp storage.
383 * Returns FALSE if suspended. The return value need be inspected only if
384 * a suspending data source is used.
388 jpeg_finish_decompress(j_decompress_ptr cinfo)
390 if ((cinfo->global_state == DSTATE_SCANNING ||
391 cinfo->global_state == DSTATE_RAW_OK) && !cinfo->buffered_image) {
392 /* Terminate final pass of non-buffered mode */
393 if (cinfo->output_scanline < cinfo->output_height)
394 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
395 (*cinfo->master->finish_output_pass) (cinfo);
396 cinfo->global_state = DSTATE_STOPPING;
397 } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
398 /* Finishing after a buffered-image operation */
399 cinfo->global_state = DSTATE_STOPPING;
400 } else if (cinfo->global_state != DSTATE_STOPPING) {
401 /* STOPPING = repeat call after a suspension, anything else is error */
402 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
405 while (!cinfo->inputctl->eoi_reached) {
406 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
407 return FALSE; /* Suspend, come back later */
409 /* Do final cleanup */
410 (*cinfo->src->term_source) (cinfo);
411 /* We can use jpeg_abort to release memory and reset global_state */
412 jpeg_abort((j_common_ptr)cinfo);