4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1998, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright (C) 2016, D. R. Commander.
8 * For conditions of distribution and use, see the accompanying README.ijg
11 * This file contains application interface code for the decompression half
12 * of the JPEG library. These are the "minimum" API routines that may be
13 * needed in either the normal full-decompression case or the
14 * transcoding-only case.
16 * Most of the routines intended to be called directly by an application
17 * are in this file or in jdapistd.c. But also see jcomapi.c for routines
18 * shared by compression and decompression, and jdtrans.c for the transcoding
22 #define JPEG_INTERNALS
29 * Initialization of a JPEG decompression object.
30 * The error manager must already be set up (in case memory manager fails).
34 jpeg_CreateDecompress(j_decompress_ptr cinfo, int version, size_t structsize)
38 /* Guard against version mismatches between library and caller. */
39 cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */
40 if (version != JPEG_LIB_VERSION)
41 ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
42 if (structsize != sizeof(struct jpeg_decompress_struct))
43 ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
44 (int)sizeof(struct jpeg_decompress_struct), (int)structsize);
46 /* For debugging purposes, we zero the whole master structure.
47 * But the application has already set the err pointer, and may have set
48 * client_data, so we have to save and restore those fields.
49 * Note: if application hasn't set client_data, tools like Purify may
53 struct jpeg_error_mgr *err = cinfo->err;
54 void *client_data = cinfo->client_data; /* ignore Purify complaint here */
55 MEMZERO(cinfo, sizeof(struct jpeg_decompress_struct));
57 cinfo->client_data = client_data;
59 cinfo->is_decompressor = TRUE;
61 /* Initialize a memory manager instance for this object */
62 jinit_memory_mgr((j_common_ptr)cinfo);
64 /* Zero out pointers to permanent structures. */
65 cinfo->progress = NULL;
68 for (i = 0; i < NUM_QUANT_TBLS; i++)
69 cinfo->quant_tbl_ptrs[i] = NULL;
71 for (i = 0; i < NUM_HUFF_TBLS; i++) {
72 cinfo->dc_huff_tbl_ptrs[i] = NULL;
73 cinfo->ac_huff_tbl_ptrs[i] = NULL;
76 /* Initialize marker processor so application can override methods
77 * for COM, APPn markers before calling jpeg_read_header.
79 cinfo->marker_list = NULL;
80 jinit_marker_reader(cinfo);
82 /* And initialize the overall input controller. */
83 jinit_input_controller(cinfo);
86 cinfo->global_state = DSTATE_START;
88 /* The master struct is used to store extension parameters, so we allocate it
91 cinfo->master = (struct jpeg_decomp_master *)
92 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
93 sizeof(my_decomp_master));
94 MEMZERO(cinfo->master, sizeof(my_decomp_master));
99 * Destruction of a JPEG decompression object
103 jpeg_destroy_decompress(j_decompress_ptr cinfo)
105 jpeg_destroy((j_common_ptr)cinfo); /* use common routine */
110 * Abort processing of a JPEG decompression operation,
111 * but don't destroy the object itself.
115 jpeg_abort_decompress(j_decompress_ptr cinfo)
117 jpeg_abort((j_common_ptr)cinfo); /* use common routine */
122 * Set default decompression parameters.
126 default_decompress_parms(j_decompress_ptr cinfo)
128 /* Guess the input colorspace, and set output colorspace accordingly. */
129 /* (Wish JPEG committee had provided a real way to specify this...) */
130 /* Note application may override our guesses. */
131 switch (cinfo->num_components) {
133 cinfo->jpeg_color_space = JCS_GRAYSCALE;
134 cinfo->out_color_space = JCS_GRAYSCALE;
138 if (cinfo->saw_JFIF_marker) {
139 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
140 } else if (cinfo->saw_Adobe_marker) {
141 switch (cinfo->Adobe_transform) {
143 cinfo->jpeg_color_space = JCS_RGB;
146 cinfo->jpeg_color_space = JCS_YCbCr;
149 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
150 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
154 /* Saw no special markers, try to guess from the component IDs */
155 int cid0 = cinfo->comp_info[0].component_id;
156 int cid1 = cinfo->comp_info[1].component_id;
157 int cid2 = cinfo->comp_info[2].component_id;
159 if (cid0 == 1 && cid1 == 2 && cid2 == 3)
160 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
161 else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
162 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
164 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
165 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
168 /* Always guess RGB is proper output colorspace. */
169 cinfo->out_color_space = JCS_RGB;
173 if (cinfo->saw_Adobe_marker) {
174 switch (cinfo->Adobe_transform) {
176 cinfo->jpeg_color_space = JCS_CMYK;
179 cinfo->jpeg_color_space = JCS_YCCK;
182 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
183 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
187 /* No special markers, assume straight CMYK. */
188 cinfo->jpeg_color_space = JCS_CMYK;
190 cinfo->out_color_space = JCS_CMYK;
194 cinfo->jpeg_color_space = JCS_UNKNOWN;
195 cinfo->out_color_space = JCS_UNKNOWN;
199 /* Set defaults for other decompression parameters. */
200 cinfo->scale_num = 1; /* 1:1 scaling */
201 cinfo->scale_denom = 1;
202 cinfo->output_gamma = 1.0;
203 cinfo->buffered_image = FALSE;
204 cinfo->raw_data_out = FALSE;
205 cinfo->dct_method = JDCT_DEFAULT;
206 cinfo->do_fancy_upsampling = TRUE;
207 cinfo->do_block_smoothing = TRUE;
208 cinfo->quantize_colors = FALSE;
209 /* We set these in case application only sets quantize_colors. */
210 cinfo->dither_mode = JDITHER_FS;
211 #ifdef QUANT_2PASS_SUPPORTED
212 cinfo->two_pass_quantize = TRUE;
214 cinfo->two_pass_quantize = FALSE;
216 cinfo->desired_number_of_colors = 256;
217 cinfo->colormap = NULL;
218 /* Initialize for no mode change in buffered-image mode. */
219 cinfo->enable_1pass_quant = FALSE;
220 cinfo->enable_external_quant = FALSE;
221 cinfo->enable_2pass_quant = FALSE;
226 * Decompression startup: read start of JPEG datastream to see what's there.
227 * Need only initialize JPEG object and supply a data source before calling.
229 * This routine will read as far as the first SOS marker (ie, actual start of
230 * compressed data), and will save all tables and parameters in the JPEG
231 * object. It will also initialize the decompression parameters to default
232 * values, and finally return JPEG_HEADER_OK. On return, the application may
233 * adjust the decompression parameters and then call jpeg_start_decompress.
234 * (Or, if the application only wanted to determine the image parameters,
235 * the data need not be decompressed. In that case, call jpeg_abort or
236 * jpeg_destroy to release any temporary space.)
237 * If an abbreviated (tables only) datastream is presented, the routine will
238 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
239 * re-use the JPEG object to read the abbreviated image datastream(s).
240 * It is unnecessary (but OK) to call jpeg_abort in this case.
241 * The JPEG_SUSPENDED return code only occurs if the data source module
242 * requests suspension of the decompressor. In this case the application
243 * should load more source data and then re-call jpeg_read_header to resume
245 * If a non-suspending data source is used and require_image is TRUE, then the
246 * return code need not be inspected since only JPEG_HEADER_OK is possible.
248 * This routine is now just a front end to jpeg_consume_input, with some
249 * extra error checking.
253 jpeg_read_header(j_decompress_ptr cinfo, boolean require_image)
257 if (cinfo->global_state != DSTATE_START &&
258 cinfo->global_state != DSTATE_INHEADER)
259 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
261 retcode = jpeg_consume_input(cinfo);
264 case JPEG_REACHED_SOS:
265 retcode = JPEG_HEADER_OK;
267 case JPEG_REACHED_EOI:
268 if (require_image) /* Complain if application wanted an image */
269 ERREXIT(cinfo, JERR_NO_IMAGE);
270 /* Reset to start state; it would be safer to require the application to
271 * call jpeg_abort, but we can't change it now for compatibility reasons.
272 * A side effect is to free any temporary memory (there shouldn't be any).
274 jpeg_abort((j_common_ptr)cinfo); /* sets state = DSTATE_START */
275 retcode = JPEG_HEADER_TABLES_ONLY;
287 * Consume data in advance of what the decompressor requires.
288 * This can be called at any time once the decompressor object has
289 * been created and a data source has been set up.
291 * This routine is essentially a state machine that handles a couple
292 * of critical state-transition actions, namely initial setup and
293 * transition from header scanning to ready-for-start_decompress.
294 * All the actual input is done via the input controller's consume_input
299 jpeg_consume_input(j_decompress_ptr cinfo)
301 int retcode = JPEG_SUSPENDED;
303 /* NB: every possible DSTATE value should be listed in this switch */
304 switch (cinfo->global_state) {
306 /* Start-of-datastream actions: reset appropriate modules */
307 (*cinfo->inputctl->reset_input_controller) (cinfo);
308 /* Initialize application's data source module */
309 (*cinfo->src->init_source) (cinfo);
310 cinfo->global_state = DSTATE_INHEADER;
312 case DSTATE_INHEADER:
313 retcode = (*cinfo->inputctl->consume_input) (cinfo);
314 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
315 /* Set up default parameters based on header data */
316 default_decompress_parms(cinfo);
317 /* Set global state: ready for start_decompress */
318 cinfo->global_state = DSTATE_READY;
322 /* Can't advance past first SOS until start_decompress is called */
323 retcode = JPEG_REACHED_SOS;
327 case DSTATE_SCANNING:
329 case DSTATE_BUFIMAGE:
331 case DSTATE_STOPPING:
332 retcode = (*cinfo->inputctl->consume_input) (cinfo);
335 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
342 * Have we finished reading the input file?
346 jpeg_input_complete(j_decompress_ptr cinfo)
348 /* Check for valid jpeg object */
349 if (cinfo->global_state < DSTATE_START ||
350 cinfo->global_state > DSTATE_STOPPING)
351 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
352 return cinfo->inputctl->eoi_reached;
357 * Is there more than one scan?
361 jpeg_has_multiple_scans(j_decompress_ptr cinfo)
363 /* Only valid after jpeg_read_header completes */
364 if (cinfo->global_state < DSTATE_READY ||
365 cinfo->global_state > DSTATE_STOPPING)
366 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
367 return cinfo->inputctl->has_multiple_scans;
372 * Finish JPEG decompression.
374 * This will normally just verify the file trailer and release temp storage.
376 * Returns FALSE if suspended. The return value need be inspected only if
377 * a suspending data source is used.
381 jpeg_finish_decompress(j_decompress_ptr cinfo)
383 if ((cinfo->global_state == DSTATE_SCANNING ||
384 cinfo->global_state == DSTATE_RAW_OK) && !cinfo->buffered_image) {
385 /* Terminate final pass of non-buffered mode */
386 if (cinfo->output_scanline < cinfo->output_height)
387 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
388 (*cinfo->master->finish_output_pass) (cinfo);
389 cinfo->global_state = DSTATE_STOPPING;
390 } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
391 /* Finishing after a buffered-image operation */
392 cinfo->global_state = DSTATE_STOPPING;
393 } else if (cinfo->global_state != DSTATE_STOPPING) {
394 /* STOPPING = repeat call after a suspension, anything else is error */
395 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
398 while (!cinfo->inputctl->eoi_reached) {
399 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
400 return FALSE; /* Suspend, come back later */
402 /* Do final cleanup */
403 (*cinfo->src->term_source) (cinfo);
404 /* We can use jpeg_abort to release memory and reset global_state */
405 jpeg_abort((j_common_ptr)cinfo);