1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * jdapistd.c
7 *
8 * Copyright (C) 1994-1996, Thomas G. Lane.
9 * This file is part of the Independent JPEG Group's software.
10 * For conditions of distribution and use, see the accompanying README file.
11 *
12 * This file contains application interface code for the decompression half
13 * of the JPEG library. These are the "standard" API routines that are
14 * used in the normal full-decompression case. They are not used by a
15 * transcoding-only application. Note that if an application links in
16 * jpeg_start_decompress, it will end up linking in the entire decompressor.
17 * We thus must separate this file from jdapimin.c to avoid linking the
18 * whole decompression library into a transcoder.
19 */
20
21#define JPEG_INTERNALS
22#include "jinclude.h"
23#include "jpeglib.h"
24
25
26/* Forward declarations */
27LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
28
29
30/*
31 * Decompression initialization.
32 * jpeg_read_header must be completed before calling this.
33 *
34 * If a multipass operating mode was selected, this will do all but the
35 * last pass, and thus may take a great deal of time.
36 *
37 * Returns FALSE if suspended. The return value need be inspected only if
38 * a suspending data source is used.
39 */
40
41GLOBAL(boolean)
42jpeg_start_decompress (j_decompress_ptr cinfo)
43{
44 if (cinfo->global_state == DSTATE_READY) {
45 /* First call: initialize master control, select active modules */
46 jinit_master_decompress(cinfo);
47 if (cinfo->buffered_image) {
48 /* No more work here; expecting jpeg_start_output next */
49 cinfo->global_state = DSTATE_BUFIMAGE;
50 return TRUE;
51 }
52 cinfo->global_state = DSTATE_PRELOAD;
53 }
54 if (cinfo->global_state == DSTATE_PRELOAD) {
55 /* If file has multiple scans, absorb them all into the coef buffer */
56 if (cinfo->inputctl->has_multiple_scans) {
57#ifdef D_MULTISCAN_FILES_SUPPORTED
58 for (;;) {
59 int retcode;
60 /* Call progress monitor hook if present */
61 if (cinfo->progress != NULL)
62 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
63 /* Absorb some more input */
64 retcode = (*cinfo->inputctl->consume_input) (cinfo);
65 if (retcode == JPEG_SUSPENDED)
66 return FALSE;
67 if (retcode == JPEG_REACHED_EOI)
68 break;
69 /* Advance progress counter if appropriate */
70 if (cinfo->progress != NULL &&
71 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
72 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
73 /* jdmaster underestimated number of scans; ratchet up one scan */
74 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
75 }
76 }
77 }
78#else
79 ERREXIT(cinfo, JERR_NOT_COMPILED);
80#endif /* D_MULTISCAN_FILES_SUPPORTED */
81 }
82 cinfo->output_scan_number = cinfo->input_scan_number;
83 } else if (cinfo->global_state != DSTATE_PRESCAN)
84 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
85 /* Perform any dummy output passes, and set up for the final pass */
86 return output_pass_setup(cinfo);
87}
88
89
90/*
91 * Set up for an output pass, and perform any dummy pass(es) needed.
92 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
93 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
94 * Exit: If done, returns TRUE and sets global_state for proper output mode.
95 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
96 */
97
98LOCAL(boolean)
99output_pass_setup (j_decompress_ptr cinfo)
100{
101 if (cinfo->global_state != DSTATE_PRESCAN) {
102 /* First call: do pass setup */
103 (*cinfo->master->prepare_for_output_pass) (cinfo);
104 cinfo->output_scanline = 0;
105 cinfo->global_state = DSTATE_PRESCAN;
106 }
107 /* Loop over any required dummy passes */
108 while (cinfo->master->is_dummy_pass) {
109#ifdef QUANT_2PASS_SUPPORTED
110 /* Crank through the dummy pass */
111 while (cinfo->output_scanline < cinfo->output_height) {
112 JDIMENSION last_scanline;
113 /* Call progress monitor hook if present */
114 if (cinfo->progress != NULL) {
115 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
116 cinfo->progress->pass_limit = (long) cinfo->output_height;
117 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
118 }
119 /* Process some data */
120 last_scanline = cinfo->output_scanline;
121 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
122 &cinfo->output_scanline, (JDIMENSION) 0);
123 if (cinfo->output_scanline == last_scanline)
124 return FALSE; /* No progress made, must suspend */
125 }
126 /* Finish up dummy pass, and set up for another one */
127 (*cinfo->master->finish_output_pass) (cinfo);
128 (*cinfo->master->prepare_for_output_pass) (cinfo);
129 cinfo->output_scanline = 0;
130#else
131 ERREXIT(cinfo, JERR_NOT_COMPILED);
132#endif /* QUANT_2PASS_SUPPORTED */
133 }
134 /* Ready for application to drive output pass through
135 * jpeg_read_scanlines or jpeg_read_raw_data.
136 */
137 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
138 return TRUE;
139}
140
141
142/*
143 * Read some scanlines of data from the JPEG decompressor.
144 *
145 * The return value will be the number of lines actually read.
146 * This may be less than the number requested in several cases,
147 * including bottom of image, data source suspension, and operating
148 * modes that emit multiple scanlines at a time.
149 *
150 * Note: we warn about excess calls to jpeg_read_scanlines() since
151 * this likely signals an application programmer error. However,
152 * an oversize buffer (max_lines > scanlines remaining) is not an error.
153 */
154
155GLOBAL(JDIMENSION)
156jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
157 JDIMENSION max_lines)
158{
159 JDIMENSION row_ctr;
160
161 if (cinfo->global_state != DSTATE_SCANNING)
162 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
163 if (cinfo->output_scanline >= cinfo->output_height) {
164 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
165 return 0;
166 }
167
168 /* Call progress monitor hook if present */
169 if (cinfo->progress != NULL) {
170 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
171 cinfo->progress->pass_limit = (long) cinfo->output_height;
172 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
173 }
174
175 /* Process some data */
176 row_ctr = 0;
177 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
178 cinfo->output_scanline += row_ctr;
179 return row_ctr;
180}
181
182
183/*
184 * Alternate entry point to read raw data.
185 * Processes exactly one iMCU row per call, unless suspended.
186 */
187
188GLOBAL(JDIMENSION)
189jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
190 JDIMENSION max_lines)
191{
192 JDIMENSION lines_per_iMCU_row;
193
194 if (cinfo->global_state != DSTATE_RAW_OK)
195 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
196 if (cinfo->output_scanline >= cinfo->output_height) {
197 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
198 return 0;
199 }
200
201 /* Call progress monitor hook if present */
202 if (cinfo->progress != NULL) {
203 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
204 cinfo->progress->pass_limit = (long) cinfo->output_height;
205 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
206 }
207
208 /* Verify that at least one iMCU row can be returned. */
209 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
210 if (max_lines < lines_per_iMCU_row)
211 ERREXIT(cinfo, JERR_BUFFER_SIZE);
212
213 /* Decompress directly into user's buffer. */
214 if (! (*cinfo->coef->decompress_data) (cinfo, data))
215 return 0; /* suspension forced, can do nothing more */
216
217 /* OK, we processed one iMCU row. */
218 cinfo->output_scanline += lines_per_iMCU_row;
219 return lines_per_iMCU_row;
220}
221
222
223/* Additional entry points for buffered-image mode. */
224
225#ifdef D_MULTISCAN_FILES_SUPPORTED
226
227/*
228 * Initialize for an output pass in buffered-image mode.
229 */
230
231GLOBAL(boolean)
232jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
233{
234 if (cinfo->global_state != DSTATE_BUFIMAGE &&
235 cinfo->global_state != DSTATE_PRESCAN)
236 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
237 /* Limit scan number to valid range */
238 if (scan_number <= 0)
239 scan_number = 1;
240 if (cinfo->inputctl->eoi_reached &&
241 scan_number > cinfo->input_scan_number)
242 scan_number = cinfo->input_scan_number;
243 cinfo->output_scan_number = scan_number;
244 /* Perform any dummy output passes, and set up for the real pass */
245 return output_pass_setup(cinfo);
246}
247
248
249/*
250 * Finish up after an output pass in buffered-image mode.
251 *
252 * Returns FALSE if suspended. The return value need be inspected only if
253 * a suspending data source is used.
254 */
255
256GLOBAL(boolean)
257jpeg_finish_output (j_decompress_ptr cinfo)
258{
259 if ((cinfo->global_state == DSTATE_SCANNING ||
260 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
261 /* Terminate this pass. */
262 /* We do not require the whole pass to have been completed. */
263 (*cinfo->master->finish_output_pass) (cinfo);
264 cinfo->global_state = DSTATE_BUFPOST;
265 } else if (cinfo->global_state != DSTATE_BUFPOST) {
266 /* BUFPOST = repeat call after a suspension, anything else is error */
267 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
268 }
269 /* Read markers looking for SOS or EOI */
270 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
271 ! cinfo->inputctl->eoi_reached) {
272 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
273 return FALSE; /* Suspend, come back later */
274 }
275 cinfo->global_state = DSTATE_BUFIMAGE;
276 return TRUE;
277}
278
279#endif /* D_MULTISCAN_FILES_SUPPORTED */
280