jdapistd.c revision 49967cdb30edd0479a1719eedc1dace5ba078d3f 
1/*
2 * jdapistd.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Copyright (C) 2010, D. R. Commander.
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 application interface code for the decompression half
10 * of the JPEG library.  These are the "standard" API routines that are
11 * used in the normal full-decompression case.  They are not used by a
12 * transcoding-only application.  Note that if an application links in
13 * jpeg_start_decompress, it will end up linking in the entire decompressor.
14 * We thus must separate this file from jdapimin.c to avoid linking the
15 * whole decompression library into a transcoder.
16 */
17
18#define JPEG_INTERNALS
19#include "jinclude.h"
20#include "jpeglib.h"
21#include "jpegcomp.h"
22
23
24/* Forward declarations */
25LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
26
27
28/*
29 * Decompression initialization.
30 * jpeg_read_header must be completed before calling this.
31 *
32 * If a multipass operating mode was selected, this will do all but the
33 * last pass, and thus may take a great deal of time.
34 *
35 * Returns FALSE if suspended.  The return value need be inspected only if
36 * a suspending data source is used.
37 */
38
39GLOBAL(boolean)
40jpeg_start_decompress (j_decompress_ptr cinfo)
41{
42  if (cinfo->global_state == DSTATE_READY) {
43    /* First call: initialize master control, select active modules */
44    jinit_master_decompress(cinfo);
45    if (cinfo->buffered_image) {
46      /* No more work here; expecting jpeg_start_output next */
47      cinfo->global_state = DSTATE_BUFIMAGE;
48      return TRUE;
49    }
50    cinfo->global_state = DSTATE_PRELOAD;
51  }
52  if (cinfo->global_state == DSTATE_PRELOAD) {
53    /* If file has multiple scans, absorb them all into the coef buffer */
54    if (cinfo->inputctl->has_multiple_scans) {
55#ifdef D_MULTISCAN_FILES_SUPPORTED
56      for (;;) {
57	int retcode;
58	/* Call progress monitor hook if present */
59	if (cinfo->progress != NULL)
60	  (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
61	/* Absorb some more input */
62	retcode = (*cinfo->inputctl->consume_input) (cinfo);
63	if (retcode == JPEG_SUSPENDED)
64	  return FALSE;
65	if (retcode == JPEG_REACHED_EOI)
66	  break;
67	/* Advance progress counter if appropriate */
68	if (cinfo->progress != NULL &&
69	    (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
70	  if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
71	    /* jdmaster underestimated number of scans; ratchet up one scan */
72	    cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
73	  }
74	}
75      }
76#else
77      ERREXIT(cinfo, JERR_NOT_COMPILED);
78#endif /* D_MULTISCAN_FILES_SUPPORTED */
79    }
80    cinfo->output_scan_number = cinfo->input_scan_number;
81  } else if (cinfo->global_state != DSTATE_PRESCAN)
82    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
83  /* Perform any dummy output passes, and set up for the final pass */
84  return output_pass_setup(cinfo);
85}
86
87
88/*
89 * Set up for an output pass, and perform any dummy pass(es) needed.
90 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
91 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
92 * Exit: If done, returns TRUE and sets global_state for proper output mode.
93 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
94 */
95
96LOCAL(boolean)
97output_pass_setup (j_decompress_ptr cinfo)
98{
99  if (cinfo->global_state != DSTATE_PRESCAN) {
100    /* First call: do pass setup */
101    (*cinfo->master->prepare_for_output_pass) (cinfo);
102    cinfo->output_scanline = 0;
103    cinfo->global_state = DSTATE_PRESCAN;
104  }
105  /* Loop over any required dummy passes */
106  while (cinfo->master->is_dummy_pass) {
107#ifdef QUANT_2PASS_SUPPORTED
108    /* Crank through the dummy pass */
109    while (cinfo->output_scanline < cinfo->output_height) {
110      JDIMENSION last_scanline;
111      /* Call progress monitor hook if present */
112      if (cinfo->progress != NULL) {
113	cinfo->progress->pass_counter = (long) cinfo->output_scanline;
114	cinfo->progress->pass_limit = (long) cinfo->output_height;
115	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
116      }
117      /* Process some data */
118      last_scanline = cinfo->output_scanline;
119      (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
120				    &cinfo->output_scanline, (JDIMENSION) 0);
121      if (cinfo->output_scanline == last_scanline)
122	return FALSE;		/* No progress made, must suspend */
123    }
124    /* Finish up dummy pass, and set up for another one */
125    (*cinfo->master->finish_output_pass) (cinfo);
126    (*cinfo->master->prepare_for_output_pass) (cinfo);
127    cinfo->output_scanline = 0;
128#else
129    ERREXIT(cinfo, JERR_NOT_COMPILED);
130#endif /* QUANT_2PASS_SUPPORTED */
131  }
132  /* Ready for application to drive output pass through
133   * jpeg_read_scanlines or jpeg_read_raw_data.
134   */
135  cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
136  return TRUE;
137}
138
139
140/*
141 * Read some scanlines of data from the JPEG decompressor.
142 *
143 * The return value will be the number of lines actually read.
144 * This may be less than the number requested in several cases,
145 * including bottom of image, data source suspension, and operating
146 * modes that emit multiple scanlines at a time.
147 *
148 * Note: we warn about excess calls to jpeg_read_scanlines() since
149 * this likely signals an application programmer error.  However,
150 * an oversize buffer (max_lines > scanlines remaining) is not an error.
151 */
152
153GLOBAL(JDIMENSION)
154jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
155		     JDIMENSION max_lines)
156{
157  JDIMENSION row_ctr;
158
159  if (cinfo->global_state != DSTATE_SCANNING)
160    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
161  if (cinfo->output_scanline >= cinfo->output_height) {
162    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
163    return 0;
164  }
165
166  /* Call progress monitor hook if present */
167  if (cinfo->progress != NULL) {
168    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
169    cinfo->progress->pass_limit = (long) cinfo->output_height;
170    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
171  }
172
173  /* Process some data */
174  row_ctr = 0;
175  (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
176  cinfo->output_scanline += row_ctr;
177  return row_ctr;
178}
179
180
181/*
182 * Alternate entry point to read raw data.
183 * Processes exactly one iMCU row per call, unless suspended.
184 */
185
186GLOBAL(JDIMENSION)
187jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
188		    JDIMENSION max_lines)
189{
190  JDIMENSION lines_per_iMCU_row;
191
192  if (cinfo->global_state != DSTATE_RAW_OK)
193    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
194  if (cinfo->output_scanline >= cinfo->output_height) {
195    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
196    return 0;
197  }
198
199  /* Call progress monitor hook if present */
200  if (cinfo->progress != NULL) {
201    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
202    cinfo->progress->pass_limit = (long) cinfo->output_height;
203    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
204  }
205
206  /* Verify that at least one iMCU row can be returned. */
207  lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
208  if (max_lines < lines_per_iMCU_row)
209    ERREXIT(cinfo, JERR_BUFFER_SIZE);
210
211  /* Decompress directly into user's buffer. */
212  if (! (*cinfo->coef->decompress_data) (cinfo, data))
213    return 0;			/* suspension forced, can do nothing more */
214
215  /* OK, we processed one iMCU row. */
216  cinfo->output_scanline += lines_per_iMCU_row;
217  return lines_per_iMCU_row;
218}
219
220
221/* Additional entry points for buffered-image mode. */
222
223#ifdef D_MULTISCAN_FILES_SUPPORTED
224
225/*
226 * Initialize for an output pass in buffered-image mode.
227 */
228
229GLOBAL(boolean)
230jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
231{
232  if (cinfo->global_state != DSTATE_BUFIMAGE &&
233      cinfo->global_state != DSTATE_PRESCAN)
234    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
235  /* Limit scan number to valid range */
236  if (scan_number <= 0)
237    scan_number = 1;
238  if (cinfo->inputctl->eoi_reached &&
239      scan_number > cinfo->input_scan_number)
240    scan_number = cinfo->input_scan_number;
241  cinfo->output_scan_number = scan_number;
242  /* Perform any dummy output passes, and set up for the real pass */
243  return output_pass_setup(cinfo);
244}
245
246
247/*
248 * Finish up after an output pass in buffered-image mode.
249 *
250 * Returns FALSE if suspended.  The return value need be inspected only if
251 * a suspending data source is used.
252 */
253
254GLOBAL(boolean)
255jpeg_finish_output (j_decompress_ptr cinfo)
256{
257  if ((cinfo->global_state == DSTATE_SCANNING ||
258       cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
259    /* Terminate this pass. */
260    /* We do not require the whole pass to have been completed. */
261    (*cinfo->master->finish_output_pass) (cinfo);
262    cinfo->global_state = DSTATE_BUFPOST;
263  } else if (cinfo->global_state != DSTATE_BUFPOST) {
264    /* BUFPOST = repeat call after a suspension, anything else is error */
265    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
266  }
267  /* Read markers looking for SOS or EOI */
268  while (cinfo->input_scan_number <= cinfo->output_scan_number &&
269	 ! cinfo->inputctl->eoi_reached) {
270    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
271      return FALSE;		/* Suspend, come back later */
272  }
273  cinfo->global_state = DSTATE_BUFIMAGE;
274  return TRUE;
275}
276
277#endif /* D_MULTISCAN_FILES_SUPPORTED */
278