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)
30 5 : 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 5 : cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */
36 5 : if (version != JPEG_LIB_VERSION)
37 0 : ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
38 5 : if (structsize != SIZEOF(struct jpeg_decompress_struct))
39 0 : 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 5 : struct jpeg_error_mgr * err = cinfo->err;
50 5 : void * client_data = cinfo->client_data; /* ignore Purify complaint here */
51 5 : MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
52 5 : cinfo->err = err;
53 5 : cinfo->client_data = client_data;
54 : }
55 5 : cinfo->is_decompressor = TRUE;
56 :
57 : /* Initialize a memory manager instance for this object */
58 5 : jinit_memory_mgr((j_common_ptr) cinfo);
59 :
60 : /* Zero out pointers to permanent structures. */
61 5 : cinfo->progress = NULL;
62 5 : cinfo->src = NULL;
63 :
64 25 : for (i = 0; i < NUM_QUANT_TBLS; i++)
65 20 : cinfo->quant_tbl_ptrs[i] = NULL;
66 :
67 25 : for (i = 0; i < NUM_HUFF_TBLS; i++) {
68 20 : cinfo->dc_huff_tbl_ptrs[i] = NULL;
69 20 : 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 5 : cinfo->marker_list = NULL;
76 5 : jinit_marker_reader(cinfo);
77 :
78 : /* And initialize the overall input controller. */
79 5 : jinit_input_controller(cinfo);
80 :
81 : /* OK, I'm ready */
82 5 : cinfo->global_state = DSTATE_START;
83 5 : }
84 :
85 :
86 : /*
87 : * Destruction of a JPEG decompression object
88 : */
89 :
90 : GLOBAL(void)
91 5 : jpeg_destroy_decompress (j_decompress_ptr cinfo)
92 : {
93 5 : jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
94 5 : }
95 :
96 :
97 : /*
98 : * Abort processing of a JPEG decompression operation,
99 : * but don't destroy the object itself.
100 : */
101 :
102 : GLOBAL(void)
103 0 : jpeg_abort_decompress (j_decompress_ptr cinfo)
104 : {
105 0 : jpeg_abort((j_common_ptr) cinfo); /* use common routine */
106 0 : }
107 :
108 :
109 : /*
110 : * Set default decompression parameters.
111 : */
112 :
113 : LOCAL(void)
114 5 : 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 5 : switch (cinfo->num_components) {
120 : case 1:
121 0 : cinfo->jpeg_color_space = JCS_GRAYSCALE;
122 0 : cinfo->out_color_space = JCS_GRAYSCALE;
123 0 : break;
124 :
125 : case 3:
126 5 : if (cinfo->saw_JFIF_marker) {
127 5 : cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
128 0 : } else if (cinfo->saw_Adobe_marker) {
129 0 : switch (cinfo->Adobe_transform) {
130 : case 0:
131 0 : cinfo->jpeg_color_space = JCS_RGB;
132 0 : break;
133 : case 1:
134 0 : cinfo->jpeg_color_space = JCS_YCbCr;
135 0 : break;
136 : default:
137 0 : WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
138 0 : cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
139 0 : break;
140 : }
141 : } else {
142 : /* Saw no special markers, try to guess from the component IDs */
143 0 : int cid0 = cinfo->comp_info[0].component_id;
144 0 : int cid1 = cinfo->comp_info[1].component_id;
145 0 : int cid2 = cinfo->comp_info[2].component_id;
146 :
147 0 : if (cid0 == 1 && cid1 == 2 && cid2 == 3)
148 0 : cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
149 0 : else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
150 0 : cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
151 : else {
152 0 : TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
153 0 : cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
154 : }
155 : }
156 : /* Always guess RGB is proper output colorspace. */
157 5 : cinfo->out_color_space = JCS_RGB;
158 5 : break;
159 :
160 : case 4:
161 0 : if (cinfo->saw_Adobe_marker) {
162 0 : switch (cinfo->Adobe_transform) {
163 : case 0:
164 0 : cinfo->jpeg_color_space = JCS_CMYK;
165 0 : break;
166 : case 2:
167 0 : cinfo->jpeg_color_space = JCS_YCCK;
168 0 : break;
169 : default:
170 0 : WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
171 0 : cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
172 0 : break;
173 : }
174 : } else {
175 : /* No special markers, assume straight CMYK. */
176 0 : cinfo->jpeg_color_space = JCS_CMYK;
177 : }
178 0 : cinfo->out_color_space = JCS_CMYK;
179 0 : break;
180 :
181 : default:
182 0 : cinfo->jpeg_color_space = JCS_UNKNOWN;
183 0 : cinfo->out_color_space = JCS_UNKNOWN;
184 0 : break;
185 : }
186 :
187 : /* Set defaults for other decompression parameters. */
188 5 : cinfo->scale_num = 1; /* 1:1 scaling */
189 5 : cinfo->scale_denom = 1;
190 5 : cinfo->output_gamma = 1.0;
191 5 : cinfo->buffered_image = FALSE;
192 5 : cinfo->raw_data_out = FALSE;
193 5 : cinfo->dct_method = JDCT_DEFAULT;
194 5 : cinfo->do_fancy_upsampling = TRUE;
195 5 : cinfo->do_block_smoothing = TRUE;
196 5 : cinfo->quantize_colors = FALSE;
197 : /* We set these in case application only sets quantize_colors. */
198 5 : cinfo->dither_mode = JDITHER_FS;
199 : #ifdef QUANT_2PASS_SUPPORTED
200 5 : cinfo->two_pass_quantize = TRUE;
201 : #else
202 : cinfo->two_pass_quantize = FALSE;
203 : #endif
204 5 : cinfo->desired_number_of_colors = 256;
205 5 : cinfo->colormap = NULL;
206 : /* Initialize for no mode change in buffered-image mode. */
207 5 : cinfo->enable_1pass_quant = FALSE;
208 5 : cinfo->enable_external_quant = FALSE;
209 5 : cinfo->enable_2pass_quant = FALSE;
210 5 : }
211 :
212 :
213 : /*
214 : * Decompression startup: read start of JPEG datastream to see what's there.
215 : * Need only initialize JPEG object and supply a data source before calling.
216 : *
217 : * This routine will read as far as the first SOS marker (ie, actual start of
218 : * compressed data), and will save all tables and parameters in the JPEG
219 : * object. It will also initialize the decompression parameters to default
220 : * values, and finally return JPEG_HEADER_OK. On return, the application may
221 : * adjust the decompression parameters and then call jpeg_start_decompress.
222 : * (Or, if the application only wanted to determine the image parameters,
223 : * the data need not be decompressed. In that case, call jpeg_abort or
224 : * jpeg_destroy to release any temporary space.)
225 : * If an abbreviated (tables only) datastream is presented, the routine will
226 : * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
227 : * re-use the JPEG object to read the abbreviated image datastream(s).
228 : * It is unnecessary (but OK) to call jpeg_abort in this case.
229 : * The JPEG_SUSPENDED return code only occurs if the data source module
230 : * requests suspension of the decompressor. In this case the application
231 : * should load more source data and then re-call jpeg_read_header to resume
232 : * processing.
233 : * If a non-suspending data source is used and require_image is TRUE, then the
234 : * return code need not be inspected since only JPEG_HEADER_OK is possible.
235 : *
236 : * This routine is now just a front end to jpeg_consume_input, with some
237 : * extra error checking.
238 : */
239 :
240 : GLOBAL(int)
241 6 : jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
242 : {
243 : int retcode;
244 :
245 7 : if (cinfo->global_state != DSTATE_START &&
246 1 : cinfo->global_state != DSTATE_INHEADER)
247 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
248 :
249 6 : retcode = jpeg_consume_input(cinfo);
250 :
251 6 : switch (retcode) {
252 : case JPEG_REACHED_SOS:
253 5 : retcode = JPEG_HEADER_OK;
254 5 : break;
255 : case JPEG_REACHED_EOI:
256 0 : if (require_image) /* Complain if application wanted an image */
257 0 : ERREXIT(cinfo, JERR_NO_IMAGE);
258 : /* Reset to start state; it would be safer to require the application to
259 : * call jpeg_abort, but we can't change it now for compatibility reasons.
260 : * A side effect is to free any temporary memory (there shouldn't be any).
261 : */
262 0 : jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
263 0 : retcode = JPEG_HEADER_TABLES_ONLY;
264 0 : break;
265 : case JPEG_SUSPENDED:
266 : /* no work */
267 1 : break;
268 : }
269 :
270 6 : return retcode;
271 : }
272 :
273 :
274 : /*
275 : * Consume data in advance of what the decompressor requires.
276 : * This can be called at any time once the decompressor object has
277 : * been created and a data source has been set up.
278 : *
279 : * This routine is essentially a state machine that handles a couple
280 : * of critical state-transition actions, namely initial setup and
281 : * transition from header scanning to ready-for-start_decompress.
282 : * All the actual input is done via the input controller's consume_input
283 : * method.
284 : */
285 :
286 : GLOBAL(int)
287 6 : jpeg_consume_input (j_decompress_ptr cinfo)
288 : {
289 6 : int retcode = JPEG_SUSPENDED;
290 :
291 : /* NB: every possible DSTATE value should be listed in this switch */
292 6 : switch (cinfo->global_state) {
293 : case DSTATE_START:
294 : /* Start-of-datastream actions: reset appropriate modules */
295 5 : (*cinfo->inputctl->reset_input_controller) (cinfo);
296 : /* Initialize application's data source module */
297 5 : (*cinfo->src->init_source) (cinfo);
298 5 : cinfo->global_state = DSTATE_INHEADER;
299 : /*FALLTHROUGH*/
300 : case DSTATE_INHEADER:
301 6 : retcode = (*cinfo->inputctl->consume_input) (cinfo);
302 6 : if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
303 : /* Set up default parameters based on header data */
304 5 : default_decompress_parms(cinfo);
305 : /* Set global state: ready for start_decompress */
306 5 : cinfo->global_state = DSTATE_READY;
307 : }
308 6 : break;
309 : case DSTATE_READY:
310 : /* Can't advance past first SOS until start_decompress is called */
311 0 : retcode = JPEG_REACHED_SOS;
312 0 : break;
313 : case DSTATE_PRELOAD:
314 : case DSTATE_PRESCAN:
315 : case DSTATE_SCANNING:
316 : case DSTATE_RAW_OK:
317 : case DSTATE_BUFIMAGE:
318 : case DSTATE_BUFPOST:
319 : case DSTATE_STOPPING:
320 0 : retcode = (*cinfo->inputctl->consume_input) (cinfo);
321 0 : break;
322 : default:
323 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
324 : }
325 6 : return retcode;
326 : }
327 :
328 :
329 : /*
330 : * Have we finished reading the input file?
331 : */
332 :
333 : GLOBAL(boolean)
334 0 : jpeg_input_complete (j_decompress_ptr cinfo)
335 : {
336 : /* Check for valid jpeg object */
337 0 : if (cinfo->global_state < DSTATE_START ||
338 0 : cinfo->global_state > DSTATE_STOPPING)
339 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
340 0 : return cinfo->inputctl->eoi_reached;
341 : }
342 :
343 :
344 : /*
345 : * Is there more than one scan?
346 : */
347 :
348 : GLOBAL(boolean)
349 5 : jpeg_has_multiple_scans (j_decompress_ptr cinfo)
350 : {
351 : /* Only valid after jpeg_read_header completes */
352 10 : if (cinfo->global_state < DSTATE_READY ||
353 5 : cinfo->global_state > DSTATE_STOPPING)
354 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
355 5 : return cinfo->inputctl->has_multiple_scans;
356 : }
357 :
358 :
359 : /*
360 : * Finish JPEG decompression.
361 : *
362 : * This will normally just verify the file trailer and release temp storage.
363 : *
364 : * Returns FALSE if suspended. The return value need be inspected only if
365 : * a suspending data source is used.
366 : */
367 :
368 : GLOBAL(boolean)
369 5 : jpeg_finish_decompress (j_decompress_ptr cinfo)
370 : {
371 5 : if ((cinfo->global_state == DSTATE_SCANNING ||
372 5 : cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
373 : /* Terminate final pass of non-buffered mode */
374 5 : if (cinfo->output_scanline < cinfo->output_height)
375 0 : ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
376 5 : (*cinfo->master->finish_output_pass) (cinfo);
377 5 : cinfo->global_state = DSTATE_STOPPING;
378 0 : } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
379 : /* Finishing after a buffered-image operation */
380 0 : cinfo->global_state = DSTATE_STOPPING;
381 0 : } else if (cinfo->global_state != DSTATE_STOPPING) {
382 : /* STOPPING = repeat call after a suspension, anything else is error */
383 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
384 : }
385 : /* Read until EOI */
386 15 : while (! cinfo->inputctl->eoi_reached) {
387 5 : if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
388 0 : return FALSE; /* Suspend, come back later */
389 : }
390 : /* Do final cleanup */
391 5 : (*cinfo->src->term_source) (cinfo);
392 : /* We can use jpeg_abort to release memory and reset global_state */
393 5 : jpeg_abort((j_common_ptr) cinfo);
394 5 : return TRUE;
395 : }
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