1 /*
2 * jwrjfif.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 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 routines to write standard JPEG file headers/markers.
9 * The file format created is a raw JPEG data stream with (optionally) an
10 * APP0 marker per the JFIF spec. This will handle baseline and
11 * JFIF-convention JPEG files, although there is currently no provision
12 * for inserting a thumbnail image in the JFIF header.
13 *
14 * These routines may need modification for non-Unix environments or
15 * specialized applications. As they stand, they assume output to
16 * an ordinary stdio stream. However, the changes to write to something
17 * else are localized in the macros appearing just below.
18 *
19 * These routines are invoked via the methods write_file_header,
20 * write_scan_header, write_jpeg_data, write_scan_trailer, and
21 * write_file_trailer.
22 */
23
24 #include "jinclude.h"
25
26 #ifdef JFIF_SUPPORTED
27
28
29 /*
30 * To output to something other than a stdio stream, you'd need to redefine
31 * these macros.
32 */
33
34 /* Write a single byte */
35 #define emit_byte(cinfo,x) putc((x), cinfo->output_file)
36
37 /* Write some bytes from a (char *) buffer */
38 #define WRITE_BYTES(cinfo,dataptr,datacount) \
39 { if (JFWRITE(cinfo->output_file, dataptr, datacount) \
40 != (size_t) (datacount)) \
41 ERREXIT(cinfo->emethods, "Output file write error --- out of disk space?"); }
42
43 /* Clean up and verify successful output */
44 #define CHECK_OUTPUT(cinfo) \
45 { fflush(cinfo->output_file); \
46 if (ferror(cinfo->output_file)) \
47 ERREXIT(cinfo->emethods, "Output file write error --- out of disk space?"); }
48
49
50 /* End of stdio-specific code. */
51
52
53 typedef enum { /* JPEG marker codes */
54 M_SOF0 = 0xc0,
55 M_SOF1 = 0xc1,
56 M_SOF2 = 0xc2,
57 M_SOF3 = 0xc3,
58
59 M_SOF5 = 0xc5,
60 M_SOF6 = 0xc6,
61 M_SOF7 = 0xc7,
62
63 M_JPG = 0xc8,
64 M_SOF9 = 0xc9,
65 M_SOF10 = 0xca,
66 M_SOF11 = 0xcb,
67
68 M_SOF13 = 0xcd,
69 M_SOF14 = 0xce,
70 M_SOF15 = 0xcf,
71
72 M_DHT = 0xc4,
73
74 M_DAC = 0xcc,
75
76 M_RST0 = 0xd0,
77 M_RST1 = 0xd1,
78 M_RST2 = 0xd2,
79 M_RST3 = 0xd3,
80 M_RST4 = 0xd4,
81 M_RST5 = 0xd5,
82 M_RST6 = 0xd6,
83 M_RST7 = 0xd7,
84
85 M_SOI = 0xd8,
86 M_EOI = 0xd9,
87 M_SOS = 0xda,
88 M_DQT = 0xdb,
89 M_DNL = 0xdc,
90 M_DRI = 0xdd,
91 M_DHP = 0xde,
92 M_EXP = 0xdf,
93
94 M_APP0 = 0xe0,
95 M_APP15 = 0xef,
96
97 M_JPG0 = 0xf0,
98 M_JPG13 = 0xfd,
99 M_COM = 0xfe,
100
101 M_TEM = 0x01,
102
103 M_ERROR = 0x100
104 } JPEG_MARKER;
105
106
107 LOCAL void
emit_marker(compress_info_ptr cinfo,JPEG_MARKER mark)108 emit_marker (compress_info_ptr cinfo, JPEG_MARKER mark)
109 /* Emit a marker code */
110 {
111 emit_byte(cinfo, 0xFF);
112 emit_byte(cinfo, mark);
113 }
114
115
116 LOCAL void
emit_2bytes(compress_info_ptr cinfo,int value)117 emit_2bytes (compress_info_ptr cinfo, int value)
118 /* Emit a 2-byte integer; these are always MSB first in JPEG files */
119 {
120 emit_byte(cinfo, (value >> 8) & 0xFF);
121 emit_byte(cinfo, value & 0xFF);
122 }
123
124
125 LOCAL int
emit_dqt(compress_info_ptr cinfo,int index)126 emit_dqt (compress_info_ptr cinfo, int index)
127 /* Emit a DQT marker */
128 /* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
129 {
130 QUANT_TBL_PTR data = cinfo->quant_tbl_ptrs[index];
131 int prec = 0;
132 int i;
133
134 for (i = 0; i < DCTSIZE2; i++) {
135 if (data[i] > 255)
136 prec = 1;
137 }
138
139 emit_marker(cinfo, M_DQT);
140
141 emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2);
142
143 emit_byte(cinfo, index + (prec<<4));
144
145 for (i = 0; i < DCTSIZE2; i++) {
146 if (prec)
147 emit_byte(cinfo, data[i] >> 8);
148 emit_byte(cinfo, data[i] & 0xFF);
149 }
150
151 return prec;
152 }
153
154
155 LOCAL void
emit_dht(compress_info_ptr cinfo,int index,boolean is_ac)156 emit_dht (compress_info_ptr cinfo, int index, boolean is_ac)
157 /* Emit a DHT marker */
158 {
159 HUFF_TBL * htbl;
160 int length, i;
161
162 if (is_ac) {
163 htbl = cinfo->ac_huff_tbl_ptrs[index];
164 index += 0x10; /* output index has AC bit set */
165 } else {
166 htbl = cinfo->dc_huff_tbl_ptrs[index];
167 }
168
169 if (htbl == NULL)
170 ERREXIT1(cinfo->emethods, "Huffman table 0x%02x was not defined", index);
171
172 if (! htbl->sent_table) {
173 emit_marker(cinfo, M_DHT);
174
175 length = 0;
176 for (i = 1; i <= 16; i++)
177 length += htbl->bits[i];
178
179 emit_2bytes(cinfo, length + 2 + 1 + 16);
180 emit_byte(cinfo, index);
181
182 for (i = 1; i <= 16; i++)
183 emit_byte(cinfo, htbl->bits[i]);
184
185 for (i = 0; i < length; i++)
186 emit_byte(cinfo, htbl->huffval[i]);
187
188 htbl->sent_table = TRUE;
189 }
190 }
191
192
193 LOCAL void
emit_dac(compress_info_ptr cinfo)194 emit_dac (compress_info_ptr cinfo)
195 /* Emit a DAC marker */
196 /* Since the useful info is so small, we want to emit all the tables in */
197 /* one DAC marker. Therefore this routine does its own scan of the table. */
198 {
199 char dc_in_use[NUM_ARITH_TBLS];
200 char ac_in_use[NUM_ARITH_TBLS];
201 int length, i;
202
203 for (i = 0; i < NUM_ARITH_TBLS; i++)
204 dc_in_use[i] = ac_in_use[i] = 0;
205
206 for (i = 0; i < cinfo->num_components; i++) {
207 dc_in_use[cinfo->comp_info[i].dc_tbl_no] = 1;
208 ac_in_use[cinfo->comp_info[i].ac_tbl_no] = 1;
209 }
210
211 length = 0;
212 for (i = 0; i < NUM_ARITH_TBLS; i++)
213 length += dc_in_use[i] + ac_in_use[i];
214
215 emit_marker(cinfo, M_DAC);
216
217 emit_2bytes(cinfo, length*2 + 2);
218
219 for (i = 0; i < NUM_ARITH_TBLS; i++) {
220 if (dc_in_use[i]) {
221 emit_byte(cinfo, i);
222 emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
223 }
224 if (ac_in_use[i]) {
225 emit_byte(cinfo, i + 0x10);
226 emit_byte(cinfo, cinfo->arith_ac_K[i]);
227 }
228 }
229 }
230
231
232 LOCAL void
emit_dri(compress_info_ptr cinfo)233 emit_dri (compress_info_ptr cinfo)
234 /* Emit a DRI marker */
235 {
236 emit_marker(cinfo, M_DRI);
237
238 emit_2bytes(cinfo, 4); /* fixed length */
239
240 emit_2bytes(cinfo, (int) cinfo->restart_interval);
241 }
242
243
244 LOCAL void
emit_sof(compress_info_ptr cinfo,JPEG_MARKER code)245 emit_sof (compress_info_ptr cinfo, JPEG_MARKER code)
246 /* Emit a SOF marker */
247 {
248 int i;
249
250 emit_marker(cinfo, code);
251
252 emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */
253
254 if (cinfo->image_height > 65535L || cinfo->image_width > 65535L)
255 ERREXIT(cinfo->emethods, "Maximum image dimension for JFIF is 65535 pixels");
256
257 emit_byte(cinfo, cinfo->data_precision);
258 emit_2bytes(cinfo, (int) cinfo->image_height);
259 emit_2bytes(cinfo, (int) cinfo->image_width);
260
261 emit_byte(cinfo, cinfo->num_components);
262
263 for (i = 0; i < cinfo->num_components; i++) {
264 emit_byte(cinfo, cinfo->comp_info[i].component_id);
265 emit_byte(cinfo, (cinfo->comp_info[i].h_samp_factor << 4)
266 + cinfo->comp_info[i].v_samp_factor);
267 emit_byte(cinfo, cinfo->comp_info[i].quant_tbl_no);
268 }
269 }
270
271
272 LOCAL void
emit_sos(compress_info_ptr cinfo)273 emit_sos (compress_info_ptr cinfo)
274 /* Emit a SOS marker */
275 {
276 int i;
277
278 emit_marker(cinfo, M_SOS);
279
280 emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */
281
282 emit_byte(cinfo, cinfo->comps_in_scan);
283
284 for (i = 0; i < cinfo->comps_in_scan; i++) {
285 emit_byte(cinfo, cinfo->cur_comp_info[i]->component_id);
286 emit_byte(cinfo, (cinfo->cur_comp_info[i]->dc_tbl_no << 4)
287 + cinfo->cur_comp_info[i]->ac_tbl_no);
288 }
289
290 emit_byte(cinfo, 0); /* Spectral selection start */
291 emit_byte(cinfo, DCTSIZE2-1); /* Spectral selection end */
292 emit_byte(cinfo, 0); /* Successive approximation */
293 }
294
295
296 LOCAL void
emit_jfif_app0(compress_info_ptr cinfo)297 emit_jfif_app0 (compress_info_ptr cinfo)
298 /* Emit a JFIF-compliant APP0 marker */
299 {
300 /*
301 * Length of APP0 block (2 bytes)
302 * Block ID (4 bytes - ASCII "JFIF")
303 * Zero byte (1 byte to terminate the ID string)
304 * Version Major, Minor (2 bytes - 0x01, 0x01)
305 * Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
306 * Xdpu (2 bytes - dots per unit horizontal)
307 * Ydpu (2 bytes - dots per unit vertical)
308 * Thumbnail X size (1 byte)
309 * Thumbnail Y size (1 byte)
310 */
311
312 emit_marker(cinfo, M_APP0);
313
314 emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */
315
316 emit_byte(cinfo, 0x4A); /* Identifier: ASCII "JFIF" */
317 emit_byte(cinfo, 0x46);
318 emit_byte(cinfo, 0x49);
319 emit_byte(cinfo, 0x46);
320 emit_byte(cinfo, 0);
321 emit_byte(cinfo, 1); /* Major version */
322 emit_byte(cinfo, 1); /* Minor version */
323 emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
324 emit_2bytes(cinfo, (int) cinfo->X_density);
325 emit_2bytes(cinfo, (int) cinfo->Y_density);
326 emit_byte(cinfo, 0); /* No thumbnail image */
327 emit_byte(cinfo, 0);
328 }
329
330
331 LOCAL void
emit_com(compress_info_ptr cinfo,char * dataptr,size_t datalen)332 emit_com (compress_info_ptr cinfo, char * dataptr, size_t datalen)
333 /* Emit a COM marker */
334 {
335 if ((unsigned) datalen <= (unsigned) 65533) { /* safety check */
336 emit_marker(cinfo, M_COM);
337
338 emit_2bytes(cinfo, (int) (datalen + 2)); /* length */
339
340 while (datalen--) {
341 emit_byte(cinfo, *dataptr);
342 dataptr++;
343 }
344 }
345 }
346
347
348 /*
349 * Write the file header.
350 */
351
352
353 METHODDEF void
write_file_header(compress_info_ptr cinfo)354 write_file_header (compress_info_ptr cinfo)
355 {
356 char qt_in_use[NUM_QUANT_TBLS];
357 int i, prec;
358 boolean is_baseline;
359
360 emit_marker(cinfo, M_SOI); /* first the SOI */
361
362 if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */
363 emit_jfif_app0(cinfo);
364
365 if (cinfo->comment_text != NULL) /* and an optional COM block */
366 emit_com(cinfo, cinfo->comment_text,
367 (size_t) (strlen(cinfo->comment_text)));
368
369 /* Emit DQT for each quantization table. */
370 /* Note that doing it here means we can't adjust the QTs on-the-fly. */
371 /* If we did want to do that, we'd have a problem with checking precision */
372 /* for the is_baseline determination. */
373
374 for (i = 0; i < NUM_QUANT_TBLS; i++)
375 qt_in_use[i] = 0;
376
377 for (i = 0; i < cinfo->num_components; i++)
378 qt_in_use[cinfo->comp_info[i].quant_tbl_no] = 1;
379
380 prec = 0;
381 for (i = 0; i < NUM_QUANT_TBLS; i++) {
382 if (qt_in_use[i])
383 prec += emit_dqt(cinfo, i);
384 }
385 /* now prec is nonzero iff there are any 16-bit quant tables. */
386
387 /* Check for a non-baseline specification. */
388 /* Note we assume that Huffman table numbers won't be changed later. */
389 is_baseline = TRUE;
390 if (cinfo->arith_code || (cinfo->data_precision != 8))
391 is_baseline = FALSE;
392 for (i = 0; i < cinfo->num_components; i++) {
393 if (cinfo->comp_info[i].dc_tbl_no > 1 || cinfo->comp_info[i].ac_tbl_no > 1)
394 is_baseline = FALSE;
395 }
396 if (prec && is_baseline) {
397 is_baseline = FALSE;
398 /* If it's baseline except for quantizer size, warn the user */
399 TRACEMS(cinfo->emethods, 0,
400 "Caution: quantization tables are too coarse for baseline JPEG");
401 }
402
403
404 /* Emit the proper SOF marker */
405 if (cinfo->arith_code)
406 emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */
407 else if (is_baseline)
408 emit_sof(cinfo, M_SOF0); /* SOF code for baseline implementation */
409 else
410 emit_sof(cinfo, M_SOF1); /* SOF code for non-baseline Huffman file */
411 }
412
413
414 /*
415 * Write the start of a scan (everything through the SOS marker).
416 */
417
418 METHODDEF void
write_scan_header(compress_info_ptr cinfo)419 write_scan_header (compress_info_ptr cinfo)
420 {
421 int i;
422
423 if (cinfo->arith_code) {
424 /* Emit arith conditioning info. We will have some duplication
425 * if the file has multiple scans, but it's so small it's hardly
426 * worth worrying about.
427 */
428 emit_dac(cinfo);
429 } else {
430 /* Emit Huffman tables. Note that emit_dht takes care of
431 * suppressing duplicate tables.
432 */
433 for (i = 0; i < cinfo->comps_in_scan; i++) {
434 emit_dht(cinfo, cinfo->cur_comp_info[i]->dc_tbl_no, FALSE);
435 emit_dht(cinfo, cinfo->cur_comp_info[i]->ac_tbl_no, TRUE);
436 }
437 }
438
439 /* Emit DRI if required --- note that DRI value could change for each scan.
440 * If it doesn't, a tiny amount of space is wasted in multiple-scan files.
441 * We assume DRI will never be nonzero for one scan and zero for a later one.
442 */
443 if (cinfo->restart_interval)
444 emit_dri(cinfo);
445
446 emit_sos(cinfo);
447 }
448
449
450 /*
451 * Write some bytes of compressed data within a scan.
452 */
453
454 METHODDEF void
write_jpeg_data(compress_info_ptr cinfo,char * dataptr,int datacount)455 write_jpeg_data (compress_info_ptr cinfo, char *dataptr, int datacount)
456 {
457 WRITE_BYTES(cinfo, dataptr, datacount);
458 }
459
460
461 /*
462 * Finish up after a compressed scan (series of write_jpeg_data calls).
463 */
464
465 METHODDEF void
write_scan_trailer(compress_info_ptr cinfo)466 write_scan_trailer (compress_info_ptr cinfo)
467 {
468 /* no work needed in this format */
469 }
470
471
472 /*
473 * Finish up at the end of the file.
474 */
475
476 METHODDEF void
write_file_trailer(compress_info_ptr cinfo)477 write_file_trailer (compress_info_ptr cinfo)
478 {
479 emit_marker(cinfo, M_EOI);
480 /* Make sure we wrote the output file OK */
481 CHECK_OUTPUT(cinfo);
482 }
483
484
485 /*
486 * The method selection routine for standard JPEG header writing.
487 * This should be called from c_ui_method_selection if appropriate.
488 */
489
490 GLOBAL void
jselwjfif(compress_info_ptr cinfo)491 jselwjfif (compress_info_ptr cinfo)
492 {
493 cinfo->methods->write_file_header = write_file_header;
494 cinfo->methods->write_scan_header = write_scan_header;
495 cinfo->methods->write_jpeg_data = write_jpeg_data;
496 cinfo->methods->write_scan_trailer = write_scan_trailer;
497 cinfo->methods->write_file_trailer = write_file_trailer;
498 }
499
500 #endif /* JFIF_SUPPORTED */
501