source: trunk/libjpeg/jdinput.c @ 283

Last change on this file since 283 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

File size: 13.7 KB
Line 
1/*
2 * jdinput.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 2002-2009 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains input control logic for the JPEG decompressor.
10 * These routines are concerned with controlling the decompressor's input
11 * processing (marker reading and coefficient decoding).  The actual input
12 * reading is done in jdmarker.c, jdhuff.c, and jdarith.c.
13 */
14
15#define JPEG_INTERNALS
16#include "jinclude.h"
17#include "jpeglib.h"
18
19
20/* Private state */
21
22typedef struct {
23  struct jpeg_input_controller pub; /* public fields */
24
25  boolean inheaders;            /* TRUE until first SOS is reached */
26} my_input_controller;
27
28typedef my_input_controller * my_inputctl_ptr;
29
30
31/* Forward declarations */
32METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
33
34
35/*
36 * Routines to calculate various quantities related to the size of the image.
37 */
38
39LOCAL(void)
40initial_setup (j_decompress_ptr cinfo)
41/* Called once, when first SOS marker is reached */
42{
43  int ci;
44  jpeg_component_info *compptr;
45
46  /* Make sure image isn't bigger than I can handle */
47  if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
48      (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
49    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
50
51  /* For now, precision must match compiled-in value... */
52  if (cinfo->data_precision != BITS_IN_JSAMPLE)
53    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
54
55  /* Check that number of components won't exceed internal array sizes */
56  if (cinfo->num_components > MAX_COMPONENTS)
57    ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
58             MAX_COMPONENTS);
59
60  /* Compute maximum sampling factors; check factor validity */
61  cinfo->max_h_samp_factor = 1;
62  cinfo->max_v_samp_factor = 1;
63  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
64       ci++, compptr++) {
65    if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
66        compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
67      ERREXIT(cinfo, JERR_BAD_SAMPLING);
68    cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
69                                   compptr->h_samp_factor);
70    cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
71                                   compptr->v_samp_factor);
72  }
73
74  /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
75   * In the full decompressor, this will be overridden by jdmaster.c;
76   * but in the transcoder, jdmaster.c is not used, so we must do it here.
77   */
78  cinfo->min_DCT_h_scaled_size = DCTSIZE;
79  cinfo->min_DCT_v_scaled_size = DCTSIZE;
80
81  /* Compute dimensions of components */
82  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
83       ci++, compptr++) {
84    compptr->DCT_h_scaled_size = DCTSIZE;
85    compptr->DCT_v_scaled_size = DCTSIZE;
86    /* Size in DCT blocks */
87    compptr->width_in_blocks = (JDIMENSION)
88      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
89                    (long) (cinfo->max_h_samp_factor * DCTSIZE));
90    compptr->height_in_blocks = (JDIMENSION)
91      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
92                    (long) (cinfo->max_v_samp_factor * DCTSIZE));
93    /* downsampled_width and downsampled_height will also be overridden by
94     * jdmaster.c if we are doing full decompression.  The transcoder library
95     * doesn't use these values, but the calling application might.
96     */
97    /* Size in samples */
98    compptr->downsampled_width = (JDIMENSION)
99      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
100                    (long) cinfo->max_h_samp_factor);
101    compptr->downsampled_height = (JDIMENSION)
102      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
103                    (long) cinfo->max_v_samp_factor);
104    /* Mark component needed, until color conversion says otherwise */
105    compptr->component_needed = TRUE;
106    /* Mark no quantization table yet saved for component */
107    compptr->quant_table = NULL;
108  }
109
110  /* Compute number of fully interleaved MCU rows. */
111  cinfo->total_iMCU_rows = (JDIMENSION)
112    jdiv_round_up((long) cinfo->image_height,
113                  (long) (cinfo->max_v_samp_factor*DCTSIZE));
114
115  /* Decide whether file contains multiple scans */
116  if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
117    cinfo->inputctl->has_multiple_scans = TRUE;
118  else
119    cinfo->inputctl->has_multiple_scans = FALSE;
120}
121
122
123LOCAL(void)
124per_scan_setup (j_decompress_ptr cinfo)
125/* Do computations that are needed before processing a JPEG scan */
126/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
127{
128  int ci, mcublks, tmp;
129  jpeg_component_info *compptr;
130 
131  if (cinfo->comps_in_scan == 1) {
132   
133    /* Noninterleaved (single-component) scan */
134    compptr = cinfo->cur_comp_info[0];
135   
136    /* Overall image size in MCUs */
137    cinfo->MCUs_per_row = compptr->width_in_blocks;
138    cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
139   
140    /* For noninterleaved scan, always one block per MCU */
141    compptr->MCU_width = 1;
142    compptr->MCU_height = 1;
143    compptr->MCU_blocks = 1;
144    compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
145    compptr->last_col_width = 1;
146    /* For noninterleaved scans, it is convenient to define last_row_height
147     * as the number of block rows present in the last iMCU row.
148     */
149    tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
150    if (tmp == 0) tmp = compptr->v_samp_factor;
151    compptr->last_row_height = tmp;
152   
153    /* Prepare array describing MCU composition */
154    cinfo->blocks_in_MCU = 1;
155    cinfo->MCU_membership[0] = 0;
156   
157  } else {
158   
159    /* Interleaved (multi-component) scan */
160    if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
161      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
162               MAX_COMPS_IN_SCAN);
163   
164    /* Overall image size in MCUs */
165    cinfo->MCUs_per_row = (JDIMENSION)
166      jdiv_round_up((long) cinfo->image_width,
167                    (long) (cinfo->max_h_samp_factor*DCTSIZE));
168    cinfo->MCU_rows_in_scan = (JDIMENSION)
169      jdiv_round_up((long) cinfo->image_height,
170                    (long) (cinfo->max_v_samp_factor*DCTSIZE));
171   
172    cinfo->blocks_in_MCU = 0;
173   
174    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
175      compptr = cinfo->cur_comp_info[ci];
176      /* Sampling factors give # of blocks of component in each MCU */
177      compptr->MCU_width = compptr->h_samp_factor;
178      compptr->MCU_height = compptr->v_samp_factor;
179      compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
180      compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
181      /* Figure number of non-dummy blocks in last MCU column & row */
182      tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
183      if (tmp == 0) tmp = compptr->MCU_width;
184      compptr->last_col_width = tmp;
185      tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
186      if (tmp == 0) tmp = compptr->MCU_height;
187      compptr->last_row_height = tmp;
188      /* Prepare array describing MCU composition */
189      mcublks = compptr->MCU_blocks;
190      if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
191        ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
192      while (mcublks-- > 0) {
193        cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
194      }
195    }
196   
197  }
198}
199
200
201/*
202 * Save away a copy of the Q-table referenced by each component present
203 * in the current scan, unless already saved during a prior scan.
204 *
205 * In a multiple-scan JPEG file, the encoder could assign different components
206 * the same Q-table slot number, but change table definitions between scans
207 * so that each component uses a different Q-table.  (The IJG encoder is not
208 * currently capable of doing this, but other encoders might.)  Since we want
209 * to be able to dequantize all the components at the end of the file, this
210 * means that we have to save away the table actually used for each component.
211 * We do this by copying the table at the start of the first scan containing
212 * the component.
213 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
214 * slot between scans of a component using that slot.  If the encoder does so
215 * anyway, this decoder will simply use the Q-table values that were current
216 * at the start of the first scan for the component.
217 *
218 * The decompressor output side looks only at the saved quant tables,
219 * not at the current Q-table slots.
220 */
221
222LOCAL(void)
223latch_quant_tables (j_decompress_ptr cinfo)
224{
225  int ci, qtblno;
226  jpeg_component_info *compptr;
227  JQUANT_TBL * qtbl;
228
229  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
230    compptr = cinfo->cur_comp_info[ci];
231    /* No work if we already saved Q-table for this component */
232    if (compptr->quant_table != NULL)
233      continue;
234    /* Make sure specified quantization table is present */
235    qtblno = compptr->quant_tbl_no;
236    if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
237        cinfo->quant_tbl_ptrs[qtblno] == NULL)
238      ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
239    /* OK, save away the quantization table */
240    qtbl = (JQUANT_TBL *)
241      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
242                                  SIZEOF(JQUANT_TBL));
243    MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
244    compptr->quant_table = qtbl;
245  }
246}
247
248
249/*
250 * Initialize the input modules to read a scan of compressed data.
251 * The first call to this is done by jdmaster.c after initializing
252 * the entire decompressor (during jpeg_start_decompress).
253 * Subsequent calls come from consume_markers, below.
254 */
255
256METHODDEF(void)
257start_input_pass (j_decompress_ptr cinfo)
258{
259  per_scan_setup(cinfo);
260  latch_quant_tables(cinfo);
261  (*cinfo->entropy->start_pass) (cinfo);
262  (*cinfo->coef->start_input_pass) (cinfo);
263  cinfo->inputctl->consume_input = cinfo->coef->consume_data;
264}
265
266
267/*
268 * Finish up after inputting a compressed-data scan.
269 * This is called by the coefficient controller after it's read all
270 * the expected data of the scan.
271 */
272
273METHODDEF(void)
274finish_input_pass (j_decompress_ptr cinfo)
275{
276  cinfo->inputctl->consume_input = consume_markers;
277}
278
279
280/*
281 * Read JPEG markers before, between, or after compressed-data scans.
282 * Change state as necessary when a new scan is reached.
283 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
284 *
285 * The consume_input method pointer points either here or to the
286 * coefficient controller's consume_data routine, depending on whether
287 * we are reading a compressed data segment or inter-segment markers.
288 */
289
290METHODDEF(int)
291consume_markers (j_decompress_ptr cinfo)
292{
293  my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
294  int val;
295
296  if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
297    return JPEG_REACHED_EOI;
298
299  val = (*cinfo->marker->read_markers) (cinfo);
300
301  switch (val) {
302  case JPEG_REACHED_SOS:        /* Found SOS */
303    if (inputctl->inheaders) {  /* 1st SOS */
304      initial_setup(cinfo);
305      inputctl->inheaders = FALSE;
306      /* Note: start_input_pass must be called by jdmaster.c
307       * before any more input can be consumed.  jdapimin.c is
308       * responsible for enforcing this sequencing.
309       */
310    } else {                    /* 2nd or later SOS marker */
311      if (! inputctl->pub.has_multiple_scans)
312        ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
313      start_input_pass(cinfo);
314    }
315    break;
316  case JPEG_REACHED_EOI:        /* Found EOI */
317    inputctl->pub.eoi_reached = TRUE;
318    if (inputctl->inheaders) {  /* Tables-only datastream, apparently */
319      if (cinfo->marker->saw_SOF)
320        ERREXIT(cinfo, JERR_SOF_NO_SOS);
321    } else {
322      /* Prevent infinite loop in coef ctlr's decompress_data routine
323       * if user set output_scan_number larger than number of scans.
324       */
325      if (cinfo->output_scan_number > cinfo->input_scan_number)
326        cinfo->output_scan_number = cinfo->input_scan_number;
327    }
328    break;
329  case JPEG_SUSPENDED:
330    break;
331  }
332
333  return val;
334}
335
336
337/*
338 * Reset state to begin a fresh datastream.
339 */
340
341METHODDEF(void)
342reset_input_controller (j_decompress_ptr cinfo)
343{
344  my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
345
346  inputctl->pub.consume_input = consume_markers;
347  inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
348  inputctl->pub.eoi_reached = FALSE;
349  inputctl->inheaders = TRUE;
350  /* Reset other modules */
351  (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
352  (*cinfo->marker->reset_marker_reader) (cinfo);
353  /* Reset progression state -- would be cleaner if entropy decoder did this */
354  cinfo->coef_bits = NULL;
355}
356
357
358/*
359 * Initialize the input controller module.
360 * This is called only once, when the decompression object is created.
361 */
362
363GLOBAL(void)
364jinit_input_controller (j_decompress_ptr cinfo)
365{
366  my_inputctl_ptr inputctl;
367
368  /* Create subobject in permanent pool */
369  inputctl = (my_inputctl_ptr)
370    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
371                                SIZEOF(my_input_controller));
372  cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
373  /* Initialize method pointers */
374  inputctl->pub.consume_input = consume_markers;
375  inputctl->pub.reset_input_controller = reset_input_controller;
376  inputctl->pub.start_input_pass = start_input_pass;
377  inputctl->pub.finish_input_pass = finish_input_pass;
378  /* Initialize state: can't use reset_input_controller since we don't
379   * want to try to reset other modules yet.
380   */
381  inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
382  inputctl->pub.eoi_reached = FALSE;
383  inputctl->inheaders = TRUE;
384}
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