jdtrans.c revision 70a18cd874a22452aca9e39e22275ed4538ed20b 
1/*
2 * jdtrans.c
3 *
4 * Copyright (C) 1995-1997, 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 library routines for transcoding decompression,
9 * that is, reading raw DCT coefficient arrays from an input JPEG file.
10 * The routines in jdapimin.c will also be needed by a transcoder.
11 */
12
13#define JPEG_INTERNALS
14#include "jinclude.h"
15#include "jpeglib.h"
16
17
18/* Forward declarations */
19LOCAL(void) transdecode_master_selection JPP((j_decompress_ptr cinfo));
20
21
22/*
23 * Read the coefficient arrays from a JPEG file.
24 * jpeg_read_header must be completed before calling this.
25 *
26 * The entire image is read into a set of virtual coefficient-block arrays,
27 * one per component.  The return value is a pointer to the array of
28 * virtual-array descriptors.  These can be manipulated directly via the
29 * JPEG memory manager, or handed off to jpeg_write_coefficients().
30 * To release the memory occupied by the virtual arrays, call
31 * jpeg_finish_decompress() when done with the data.
32 *
33 * An alternative usage is to simply obtain access to the coefficient arrays
34 * during a buffered-image-mode decompression operation.  This is allowed
35 * after any jpeg_finish_output() call.  The arrays can be accessed until
36 * jpeg_finish_decompress() is called.  (Note that any call to the library
37 * may reposition the arrays, so don't rely on access_virt_barray() results
38 * to stay valid across library calls.)
39 *
40 * Returns NULL if suspended.  This case need be checked only if
41 * a suspending data source is used.
42 */
43
44GLOBAL(jvirt_barray_ptr *)
45jpeg_read_coefficients (j_decompress_ptr cinfo)
46{
47  if (cinfo->global_state == DSTATE_READY) {
48    /* First call: initialize active modules */
49    transdecode_master_selection(cinfo);
50    cinfo->global_state = DSTATE_RDCOEFS;
51  }
52  if (cinfo->global_state == DSTATE_RDCOEFS) {
53    /* Absorb whole file into the coef buffer */
54    for (;;) {
55      int retcode;
56      /* Call progress monitor hook if present */
57      if (cinfo->progress != NULL)
58        (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
59      /* Absorb some more input */
60      retcode = (*cinfo->inputctl->consume_input) (cinfo);
61      if (retcode == JPEG_SUSPENDED)
62        return NULL;
63      if (retcode == JPEG_REACHED_EOI)
64        break;
65      /* Advance progress counter if appropriate */
66      if (cinfo->progress != NULL &&
67	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
68        if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
69	  /* startup underestimated number of scans; ratchet up one scan */
70        cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
71        }
72      }
73    }
74    /* Set state so that jpeg_finish_decompress does the right thing */
75    cinfo->global_state = DSTATE_STOPPING;
76  }
77  /* At this point we should be in state DSTATE_STOPPING if being used
78   * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
79   * to the coefficients during a full buffered-image-mode decompression.
80   */
81  if ((cinfo->global_state == DSTATE_STOPPING ||
82       cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
83    return cinfo->coef->coef_arrays;
84  }
85  /* Oops, improper usage */
86  ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
87  return NULL;			/* keep compiler happy */
88}
89
90LOCAL(boolean)
91jpeg_build_huffman_index_progressive(j_decompress_ptr cinfo,
92        huffman_index *index)
93{
94  if (cinfo->global_state == DSTATE_READY) {
95    printf("Progressive Mode\n");
96    /* First call: initialize active modules */
97    transdecode_master_selection(cinfo);
98    cinfo->global_state = DSTATE_RDCOEFS;
99  }
100  if (cinfo->global_state == DSTATE_RDCOEFS) {
101    int mcu, i;
102    cinfo->marker->get_sos_marker_position(cinfo, index);
103
104    /* Absorb whole file into the coef buffer */
105    for (mcu = 0; mcu < cinfo->total_iMCU_rows; mcu++) {
106      int retcode = 0;
107      /* Call progress monitor hook if present */
108      if (cinfo->progress != NULL)
109        (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
110      /* Absorb some more input */
111      jinit_phuff_decoder(cinfo);
112      for (i = 0; i < index->scan_count; i++) {
113        (*cinfo->inputctl->finish_input_pass) (cinfo);
114        jset_input_stream_position(cinfo, index->scan[i].bitstream_offset);
115        cinfo->unread_marker = 0;
116        retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
117                    (cinfo, index, i);
118        if (retcode == JPEG_REACHED_EOI)
119          break;
120        cinfo->input_iMCU_row = mcu;
121        if (mcu != 0)
122          (*cinfo->entropy->configure_huffman_decoder)
123                (cinfo, index->scan[i].prev_MCU_offset);
124        cinfo->input_scan_number = i;
125        retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
126                    (cinfo, index, i);
127      }
128      if (retcode == JPEG_SUSPENDED)
129        return FALSE;
130      if (retcode == JPEG_REACHED_EOI)
131        break;
132      /* Advance progress counter if appropriate */
133      if (cinfo->progress != NULL &&
134	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
135        if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
136	  /* startup underestimated number of scans; ratchet up one scan */
137          cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
138        }
139      }
140    }
141    cinfo->global_state = DSTATE_STOPPING;
142  }
143  /* At this point we should be in state DSTATE_STOPPING if being used
144   * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
145   * to the coefficients during a full buffered-image-mode decompression.
146   */
147  if ((cinfo->global_state == DSTATE_STOPPING ||
148       cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
149    return TRUE;
150  }
151  /* Oops, improper usage */
152  ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
153  return FALSE;			/* keep compiler happy */
154}
155
156LOCAL(boolean)
157jpeg_build_huffman_index_baseline(j_decompress_ptr cinfo, huffman_index *index)
158{
159  if (cinfo->global_state == DSTATE_READY) {
160    printf("Baseline Mode\n");
161    /* First call: initialize active modules */
162    transdecode_master_selection(cinfo);
163    cinfo->global_state = DSTATE_RDCOEFS;
164  }
165  if (cinfo->global_state == DSTATE_RDCOEFS) {
166    /* Absorb whole file into the coef buffer */
167    for (;;) {
168      int retcode;
169      /* Call progress monitor hook if present */
170      if (cinfo->progress != NULL)
171        (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
172      /* Absorb some more input */
173      retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
174                    (cinfo, index, 0);
175      if (retcode == JPEG_SUSPENDED)
176        return FALSE;
177      if (retcode == JPEG_REACHED_EOI)
178        break;
179      if (retcode == JPEG_SCAN_COMPLETED)
180        break;
181
182      /* Advance progress counter if appropriate */
183      if (cinfo->progress != NULL &&
184	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
185        if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
186	  /* startup underestimated number of scans; ratchet up one scan */
187        cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
188        }
189      }
190    }
191    /* Set state so that jpeg_finish_decompress does the right thing */
192    cinfo->global_state = DSTATE_STOPPING;
193  }
194  /* At this point we should be in state DSTATE_STOPPING if being used
195   * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
196   * to the coefficients during a full buffered-image-mode decompression.
197   */
198  if ((cinfo->global_state == DSTATE_STOPPING ||
199       cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
200    return TRUE;
201  }
202  /* Oops, improper usage */
203  ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
204  return FALSE;			/* keep compiler happy */
205}
206
207GLOBAL(boolean)
208jpeg_build_huffman_index(j_decompress_ptr cinfo, huffman_index *index)
209{
210    cinfo->tile_decode = TRUE;
211    if (cinfo->progressive_mode)
212      return jpeg_build_huffman_index_progressive(cinfo, index);
213    else
214      return jpeg_build_huffman_index_baseline(cinfo, index);
215}
216
217/*
218 * Master selection of decompression modules for transcoding.
219 * This substitutes for jdmaster.c's initialization of the full decompressor.
220 */
221
222LOCAL(void)
223transdecode_master_selection (j_decompress_ptr cinfo)
224{
225  /* This is effectively a buffered-image operation. */
226  cinfo->buffered_image = TRUE;
227
228  /* Entropy decoding: either Huffman or arithmetic coding. */
229  if (cinfo->arith_code) {
230    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
231  } else {
232    if (cinfo->progressive_mode) {
233#ifdef D_PROGRESSIVE_SUPPORTED
234      jinit_phuff_decoder(cinfo);
235#else
236      ERREXIT(cinfo, JERR_NOT_COMPILED);
237#endif
238    } else {
239      jinit_huff_decoder(cinfo);
240    }
241  }
242
243  /* Always get a full-image coefficient buffer. */
244  jinit_d_coef_controller(cinfo, TRUE);
245
246  /* We can now tell the memory manager to allocate virtual arrays. */
247  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
248
249  /* Initialize input side of decompressor to consume first scan. */
250  (*cinfo->inputctl->start_input_pass) (cinfo);
251
252  /* Initialize progress monitoring. */
253  if (cinfo->progress != NULL) {
254    int nscans;
255    /* Estimate number of scans to set pass_limit. */
256    if (cinfo->progressive_mode) {
257      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
258      nscans = 2 + 3 * cinfo->num_components;
259    } else if (cinfo->inputctl->has_multiple_scans) {
260      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
261      nscans = cinfo->num_components;
262    } else {
263      nscans = 1;
264    }
265    cinfo->progress->pass_counter = 0L;
266    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
267    cinfo->progress->completed_passes = 0;
268    cinfo->progress->total_passes = 1;
269  }
270}
271