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view libs/libjpeg/jdapimin.c @ 3:dc735bdeeb8a
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added content-scale support for "retina" devices
| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Mon, 21 Sep 2015 07:40:34 +0300 |
| parents | |
| children |
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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 */
19 #define JPEG_INTERNALS
20 #include "jinclude.h"
21 #include "jpeglib.h"
24 /*
25 * Initialization of a JPEG decompression object.
26 * The error manager must already be set up (in case memory manager fails).
27 */
29 GLOBAL(void)
30 jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
31 {
32 int i;
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);
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;
57 /* Initialize a memory manager instance for this object */
58 jinit_memory_mgr((j_common_ptr) cinfo);
60 /* Zero out pointers to permanent structures. */
61 cinfo->progress = NULL;
62 cinfo->src = NULL;
64 for (i = 0; i < NUM_QUANT_TBLS; i++)
65 cinfo->quant_tbl_ptrs[i] = NULL;
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 }
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);
78 /* And initialize the overall input controller. */
79 jinit_input_controller(cinfo);
81 /* OK, I'm ready */
82 cinfo->global_state = DSTATE_START;
83 }
86 /*
87 * Destruction of a JPEG decompression object
88 */
90 GLOBAL(void)
91 jpeg_destroy_decompress (j_decompress_ptr cinfo)
92 {
93 jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
94 }
97 /*
98 * Abort processing of a JPEG decompression operation,
99 * but don't destroy the object itself.
100 */
102 GLOBAL(void)
103 jpeg_abort_decompress (j_decompress_ptr cinfo)
104 {
105 jpeg_abort((j_common_ptr) cinfo); /* use common routine */
106 }
109 /*
110 * Set default decompression parameters.
111 */
113 LOCAL(void)
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;
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;
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 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
153 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
154 }
155 }
156 /* Always guess RGB is proper output colorspace. */
157 cinfo->out_color_space = JCS_RGB;
158 break;
160 case 4:
161 if (cinfo->saw_Adobe_marker) {
162 switch (cinfo->Adobe_transform) {
163 case 0:
164 cinfo->jpeg_color_space = JCS_CMYK;
165 break;
166 case 2:
167 cinfo->jpeg_color_space = JCS_YCCK;
168 break;
169 default:
170 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
171 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
172 break;
173 }
174 } else {
175 /* No special markers, assume straight CMYK. */
176 cinfo->jpeg_color_space = JCS_CMYK;
177 }
178 cinfo->out_color_space = JCS_CMYK;
179 break;
181 default:
182 cinfo->jpeg_color_space = JCS_UNKNOWN;
183 cinfo->out_color_space = JCS_UNKNOWN;
184 break;
185 }
187 /* Set defaults for other decompression parameters. */
188 cinfo->scale_num = 1; /* 1:1 scaling */
189 cinfo->scale_denom = 1;
190 cinfo->output_gamma = 1.0;
191 cinfo->buffered_image = FALSE;
192 cinfo->raw_data_out = FALSE;
193 cinfo->dct_method = JDCT_DEFAULT;
194 cinfo->do_fancy_upsampling = TRUE;
195 cinfo->do_block_smoothing = TRUE;
196 cinfo->quantize_colors = FALSE;
197 /* We set these in case application only sets quantize_colors. */
198 cinfo->dither_mode = JDITHER_FS;
199 #ifdef QUANT_2PASS_SUPPORTED
200 cinfo->two_pass_quantize = TRUE;
201 #else
202 cinfo->two_pass_quantize = FALSE;
203 #endif
204 cinfo->desired_number_of_colors = 256;
205 cinfo->colormap = NULL;
206 /* Initialize for no mode change in buffered-image mode. */
207 cinfo->enable_1pass_quant = FALSE;
208 cinfo->enable_external_quant = FALSE;
209 cinfo->enable_2pass_quant = FALSE;
210 }
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 */
240 GLOBAL(int)
241 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
242 {
243 int retcode;
245 if (cinfo->global_state != DSTATE_START &&
246 cinfo->global_state != DSTATE_INHEADER)
247 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
249 retcode = jpeg_consume_input(cinfo);
251 switch (retcode) {
252 case JPEG_REACHED_SOS:
253 retcode = JPEG_HEADER_OK;
254 break;
255 case JPEG_REACHED_EOI:
256 if (require_image) /* Complain if application wanted an image */
257 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 jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
263 retcode = JPEG_HEADER_TABLES_ONLY;
264 break;
265 case JPEG_SUSPENDED:
266 /* no work */
267 break;
268 }
270 return retcode;
271 }
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 */
286 GLOBAL(int)
287 jpeg_consume_input (j_decompress_ptr cinfo)
288 {
289 int retcode = JPEG_SUSPENDED;
291 /* NB: every possible DSTATE value should be listed in this switch */
292 switch (cinfo->global_state) {
293 case DSTATE_START:
294 /* Start-of-datastream actions: reset appropriate modules */
295 (*cinfo->inputctl->reset_input_controller) (cinfo);
296 /* Initialize application's data source module */
297 (*cinfo->src->init_source) (cinfo);
298 cinfo->global_state = DSTATE_INHEADER;
299 /*FALLTHROUGH*/
300 case DSTATE_INHEADER:
301 retcode = (*cinfo->inputctl->consume_input) (cinfo);
302 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
303 /* Set up default parameters based on header data */
304 default_decompress_parms(cinfo);
305 /* Set global state: ready for start_decompress */
306 cinfo->global_state = DSTATE_READY;
307 }
308 break;
309 case DSTATE_READY:
310 /* Can't advance past first SOS until start_decompress is called */
311 retcode = JPEG_REACHED_SOS;
312 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 retcode = (*cinfo->inputctl->consume_input) (cinfo);
321 break;
322 default:
323 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
324 }
325 return retcode;
326 }
329 /*
330 * Have we finished reading the input file?
331 */
333 GLOBAL(boolean)
334 jpeg_input_complete (j_decompress_ptr cinfo)
335 {
336 /* Check for valid jpeg object */
337 if (cinfo->global_state < DSTATE_START ||
338 cinfo->global_state > DSTATE_STOPPING)
339 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
340 return cinfo->inputctl->eoi_reached;
341 }
344 /*
345 * Is there more than one scan?
346 */
348 GLOBAL(boolean)
349 jpeg_has_multiple_scans (j_decompress_ptr cinfo)
350 {
351 /* Only valid after jpeg_read_header completes */
352 if (cinfo->global_state < DSTATE_READY ||
353 cinfo->global_state > DSTATE_STOPPING)
354 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
355 return cinfo->inputctl->has_multiple_scans;
356 }
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 */
368 GLOBAL(boolean)
369 jpeg_finish_decompress (j_decompress_ptr cinfo)
370 {
371 if ((cinfo->global_state == DSTATE_SCANNING ||
372 cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
373 /* Terminate final pass of non-buffered mode */
374 if (cinfo->output_scanline < cinfo->output_height)
375 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
376 (*cinfo->master->finish_output_pass) (cinfo);
377 cinfo->global_state = DSTATE_STOPPING;
378 } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
379 /* Finishing after a buffered-image operation */
380 cinfo->global_state = DSTATE_STOPPING;
381 } else if (cinfo->global_state != DSTATE_STOPPING) {
382 /* STOPPING = repeat call after a suspension, anything else is error */
383 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
384 }
385 /* Read until EOI */
386 while (! cinfo->inputctl->eoi_reached) {
387 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
388 return FALSE; /* Suspend, come back later */
389 }
390 /* Do final cleanup */
391 (*cinfo->src->term_source) (cinfo);
392 /* We can use jpeg_abort to release memory and reset global_state */
393 jpeg_abort((j_common_ptr) cinfo);
394 return TRUE;
395 }