1 /*
2 * jdapimin.c
3 *
4 * Copyright (C) 1994-1998, 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 "minimum" API routines that may be
10 * needed in either the normal full-decompression case or the
11 * transcoding-only case.
12 *
13 * Most of the routines intended to be called directly by an application
14 * are in this file or in jdapistd.c. But also see jcomapi.c for routines
15 * shared by compression and decompression, and jdtrans.c for the transcoding
16 * case.
17 */
18
19 #define JPEG_INTERNALS
20 #include "jinclude.h"
21 #include "jpeglib.h"
22
23
24 /*
25 * Initialization of a JPEG decompression object.
26 * The error manager must already be set up (in case memory manager fails).
27 */
28
29 GLOBAL(void)
jpeg_CreateDecompress(j_decompress_ptr cinfo,int version,size_t structsize)30 jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
31 {
32 int i;
33
34 /* Guard against version mismatches between library and caller. */
35 cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */
36 if (version != JPEG_LIB_VERSION)
37 ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
38 if (structsize != SIZEOF(struct jpeg_decompress_struct))
39 ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
40 (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);
41
42 /* For debugging purposes, we zero the whole master structure.
43 * But the application has already set the err pointer, and may have set
44 * client_data, so we have to save and restore those fields.
45 * Note: if application hasn't set client_data, tools like Purify may
46 * complain here.
47 */
48 {
49 struct jpeg_error_mgr * err = cinfo->err;
50 void * client_data = cinfo->client_data; /* ignore Purify complaint here */
51 MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
52 cinfo->err = err;
53 cinfo->client_data = client_data;
54 }
55 cinfo->is_decompressor = TRUE;
56
57 /* Initialize a memory manager instance for this object */
58 jinit_memory_mgr((j_common_ptr) cinfo);
59
60 /* Zero out pointers to permanent structures. */
61 cinfo->progress = NULL;
62 cinfo->src = NULL;
63
64 for (i = 0; i < NUM_QUANT_TBLS; i++)
65 cinfo->quant_tbl_ptrs[i] = NULL;
66
67 for (i = 0; i < NUM_HUFF_TBLS; i++) {
68 cinfo->dc_huff_tbl_ptrs[i] = NULL;
69 cinfo->ac_huff_tbl_ptrs[i] = NULL;
70 }
71
72 /* Initialize marker processor so application can override methods
73 * for COM, APPn markers before calling jpeg_read_header.
74 */
75 cinfo->marker_list = NULL;
76 jinit_marker_reader(cinfo);
77
78 /* And initialize the overall input controller. */
79 jinit_input_controller(cinfo);
80
81 /* OK, I'm ready */
82 cinfo->global_state = DSTATE_START;
83 }
84
85
86 /*
87 * Destruction of a JPEG decompression object
88 */
89
90 GLOBAL(void)
jpeg_destroy_decompress(j_decompress_ptr cinfo)91 jpeg_destroy_decompress (j_decompress_ptr cinfo)
92 {
93 jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
94 }
95
96
97 /*
98 * Abort processing of a JPEG decompression operation,
99 * but don't destroy the object itself.
100 */
101
102 GLOBAL(void)
jpeg_abort_decompress(j_decompress_ptr cinfo)103 jpeg_abort_decompress (j_decompress_ptr cinfo)
104 {
105 jpeg_abort((j_common_ptr) cinfo); /* use common routine */
106 }
107
108
109 /*
110 * Set default decompression parameters.
111 */
112
113 LOCAL(void)
default_decompress_parms(j_decompress_ptr cinfo)114 default_decompress_parms (j_decompress_ptr cinfo)
115 {
116 /* Guess the input colorspace, and set output colorspace accordingly. */
117 /* (Wish JPEG committee had provided a real way to specify this...) */
118 /* Note application may override our guesses. */
119 switch (cinfo->num_components) {
120 case 1:
121 cinfo->jpeg_color_space = JCS_GRAYSCALE;
122 cinfo->out_color_space = JCS_GRAYSCALE;
123 break;
124
125 case 3:
126 if (cinfo->saw_JFIF_marker) {
127 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
128 } else if (cinfo->saw_Adobe_marker) {
129 switch (cinfo->Adobe_transform) {
130 case 0:
131 cinfo->jpeg_color_space = JCS_RGB;
132 break;
133 case 1:
134 cinfo->jpeg_color_space = JCS_YCbCr;
135 break;
136 default:
137 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
138 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
139 break;
140 }
141 } else {
142 /* Saw no special markers, try to guess from the component IDs */
143 int cid0 = cinfo->comp_info[0].component_id;
144 int cid1 = cinfo->comp_info[1].component_id;
145 int cid2 = cinfo->comp_info[2].component_id;
146
147 if (cid0 == 1 && cid1 == 2 && cid2 == 3)
148 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
149 else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
150 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
151 else {
152 if (cinfo->process == JPROC_LOSSLESS) {
153 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_LOSSLESS_IDS, cid0, cid1, cid2);
154 cinfo->jpeg_color_space = JCS_RGB; /* assume it's RGB */
155 }
156 else { /* Lossy processes */
157 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_LOSSY_IDS, cid0, cid1, cid2);
158 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
159 }
160 }
161 }
162 /* Always guess RGB is proper output colorspace. */
163 cinfo->out_color_space = JCS_RGB;
164 break;
165
166 case 4:
167 if (cinfo->saw_Adobe_marker) {
168 switch (cinfo->Adobe_transform) {
169 case 0:
170 cinfo->jpeg_color_space = JCS_CMYK;
171 break;
172 case 2:
173 cinfo->jpeg_color_space = JCS_YCCK;
174 break;
175 default:
176 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
177 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
178 break;
179 }
180 } else {
181 /* No special markers, assume straight CMYK. */
182 cinfo->jpeg_color_space = JCS_CMYK;
183 }
184 cinfo->out_color_space = JCS_CMYK;
185 break;
186
187 default:
188 cinfo->jpeg_color_space = JCS_UNKNOWN;
189 cinfo->out_color_space = JCS_UNKNOWN;
190 break;
191 }
192
193 /* Set defaults for other decompression parameters. */
194 cinfo->scale_num = 1; /* 1:1 scaling */
195 cinfo->scale_denom = 1;
196 cinfo->output_gamma = 1.0;
197 cinfo->buffered_image = FALSE;
198 cinfo->raw_data_out = FALSE;
199 cinfo->dct_method = JDCT_DEFAULT;
200 cinfo->do_fancy_upsampling = TRUE;
201 cinfo->do_block_smoothing = TRUE;
202 cinfo->quantize_colors = FALSE;
203 /* We set these in case application only sets quantize_colors. */
204 cinfo->dither_mode = JDITHER_FS;
205 #ifdef QUANT_2PASS_SUPPORTED
206 cinfo->two_pass_quantize = TRUE;
207 #else
208 cinfo->two_pass_quantize = FALSE;
209 #endif
210 cinfo->desired_number_of_colors = 256;
211 cinfo->colormap = NULL;
212 /* Initialize for no mode change in buffered-image mode. */
213 cinfo->enable_1pass_quant = FALSE;
214 cinfo->enable_external_quant = FALSE;
215 cinfo->enable_2pass_quant = FALSE;
216 }
217
218
219 /*
220 * Decompression startup: read start of JPEG datastream to see what's there.
221 * Need only initialize JPEG object and supply a data source before calling.
222 *
223 * This routine will read as far as the first SOS marker (ie, actual start of
224 * compressed data), and will save all tables and parameters in the JPEG
225 * object. It will also initialize the decompression parameters to default
226 * values, and finally return JPEG_HEADER_OK. On return, the application may
227 * adjust the decompression parameters and then call jpeg_start_decompress.
228 * (Or, if the application only wanted to determine the image parameters,
229 * the data need not be decompressed. In that case, call jpeg_abort or
230 * jpeg_destroy to release any temporary space.)
231 * If an abbreviated (tables only) datastream is presented, the routine will
232 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
233 * re-use the JPEG object to read the abbreviated image datastream(s).
234 * It is unnecessary (but OK) to call jpeg_abort in this case.
235 * The JPEG_SUSPENDED return code only occurs if the data source module
236 * requests suspension of the decompressor. In this case the application
237 * should load more source data and then re-call jpeg_read_header to resume
238 * processing.
239 * If a non-suspending data source is used and require_image is TRUE, then the
240 * return code need not be inspected since only JPEG_HEADER_OK is possible.
241 *
242 * This routine is now just a front end to jpeg_consume_input, with some
243 * extra error checking.
244 */
245
246 GLOBAL(int)
jpeg_read_header(j_decompress_ptr cinfo,boolean require_image)247 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
248 {
249 int retcode;
250
251 if (cinfo->global_state != DSTATE_START &&
252 cinfo->global_state != DSTATE_INHEADER)
253 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
254
255 retcode = jpeg_consume_input(cinfo);
256
257 switch (retcode) {
258 case JPEG_REACHED_SOS:
259 retcode = JPEG_HEADER_OK;
260 break;
261 case JPEG_REACHED_EOI:
262 if (require_image) /* Complain if application wanted an image */
263 ERREXIT(cinfo, JERR_NO_IMAGE);
264 /* Reset to start state; it would be safer to require the application to
265 * call jpeg_abort, but we can't change it now for compatibility reasons.
266 * A side effect is to free any temporary memory (there shouldn't be any).
267 */
268 jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
269 retcode = JPEG_HEADER_TABLES_ONLY;
270 break;
271 case JPEG_SUSPENDED:
272 /* no work */
273 break;
274 }
275
276 return retcode;
277 }
278
279
280 /*
281 * Consume data in advance of what the decompressor requires.
282 * This can be called at any time once the decompressor object has
283 * been created and a data source has been set up.
284 *
285 * This routine is essentially a state machine that handles a couple
286 * of critical state-transition actions, namely initial setup and
287 * transition from header scanning to ready-for-start_decompress.
288 * All the actual input is done via the input controller's consume_input
289 * method.
290 */
291
292 GLOBAL(int)
jpeg_consume_input(j_decompress_ptr cinfo)293 jpeg_consume_input (j_decompress_ptr cinfo)
294 {
295 int retcode = JPEG_SUSPENDED;
296
297 /* NB: every possible DSTATE value should be listed in this switch */
298 switch (cinfo->global_state) {
299 case DSTATE_START:
300 /* Start-of-datastream actions: reset appropriate modules */
301 (*cinfo->inputctl->reset_input_controller) (cinfo);
302 /* Initialize application's data source module */
303 (*cinfo->src->init_source) (cinfo);
304 cinfo->global_state = DSTATE_INHEADER;
305 /*FALLTHROUGH*/
306 case DSTATE_INHEADER:
307 retcode = (*cinfo->inputctl->consume_input) (cinfo);
308 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
309 /* Set up default parameters based on header data */
310 default_decompress_parms(cinfo);
311 /* Set global state: ready for start_decompress */
312 cinfo->global_state = DSTATE_READY;
313 }
314 break;
315 case DSTATE_READY:
316 /* Can't advance past first SOS until start_decompress is called */
317 retcode = JPEG_REACHED_SOS;
318 break;
319 case DSTATE_PRELOAD:
320 case DSTATE_PRESCAN:
321 case DSTATE_SCANNING:
322 case DSTATE_RAW_OK:
323 case DSTATE_BUFIMAGE:
324 case DSTATE_BUFPOST:
325 case DSTATE_STOPPING:
326 retcode = (*cinfo->inputctl->consume_input) (cinfo);
327 break;
328 default:
329 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
330 }
331 return retcode;
332 }
333
334
335 /*
336 * Have we finished reading the input file?
337 */
338
339 GLOBAL(boolean)
jpeg_input_complete(j_decompress_ptr cinfo)340 jpeg_input_complete (j_decompress_ptr cinfo)
341 {
342 /* Check for valid jpeg object */
343 if (cinfo->global_state < DSTATE_START ||
344 cinfo->global_state > DSTATE_STOPPING)
345 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
346 return cinfo->inputctl->eoi_reached;
347 }
348
349
350 /*
351 * Is there more than one scan?
352 */
353
354 GLOBAL(boolean)
jpeg_has_multiple_scans(j_decompress_ptr cinfo)355 jpeg_has_multiple_scans (j_decompress_ptr cinfo)
356 {
357 /* Only valid after jpeg_read_header completes */
358 if (cinfo->global_state < DSTATE_READY ||
359 cinfo->global_state > DSTATE_STOPPING)
360 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
361 return cinfo->inputctl->has_multiple_scans;
362 }
363
364
365 /*
366 * Finish JPEG decompression.
367 *
368 * This will normally just verify the file trailer and release temp storage.
369 *
370 * Returns FALSE if suspended. The return value need be inspected only if
371 * a suspending data source is used.
372 */
373
374 GLOBAL(boolean)
jpeg_finish_decompress(j_decompress_ptr cinfo)375 jpeg_finish_decompress (j_decompress_ptr cinfo)
376 {
377 if ((cinfo->global_state == DSTATE_SCANNING ||
378 cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
379 /* Terminate final pass of non-buffered mode */
380 if (cinfo->output_scanline < cinfo->output_height)
381 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
382 (*cinfo->master->finish_output_pass) (cinfo);
383 cinfo->global_state = DSTATE_STOPPING;
384 } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
385 /* Finishing after a buffered-image operation */
386 cinfo->global_state = DSTATE_STOPPING;
387 } else if (cinfo->global_state != DSTATE_STOPPING) {
388 /* STOPPING = repeat call after a suspension, anything else is error */
389 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
390 }
391 /* Read until EOI */
392 while (! cinfo->inputctl->eoi_reached) {
393 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
394 return FALSE; /* Suspend, come back later */
395 }
396 /* Do final cleanup */
397 (*cinfo->src->term_source) (cinfo);
398 /* We can use jpeg_abort to release memory and reset global_state */
399 jpeg_abort((j_common_ptr) cinfo);
400 return TRUE;
401 }
402