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jdapistd.c (9348B)
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1 /*
2 * jdapistd.c
3 *
4 * Copyright (C) 1994-1996, 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 "standard" API routines that are
10 * used in the normal full-decompression case. They are not used by a
11 * transcoding-only application. Note that if an application links in
12 * jpeg_start_decompress, it will end up linking in the entire decompressor.
13 * We thus must separate this file from jdapimin.c to avoid linking the
14 * whole decompression library into a transcoder.
15 */
16
17 #define JPEG_INTERNALS
18 #include "jinclude.h"
19 #include "jpeglib.h"
20
21
22 /* Forward declarations */
23 LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
24
25
26 /*
27 * Decompression initialization.
28 * jpeg_read_header must be completed before calling this.
29 *
30 * If a multipass operating mode was selected, this will do all but the
31 * last pass, and thus may take a great deal of time.
32 *
33 * Returns FALSE if suspended. The return value need be inspected only if
34 * a suspending data source is used.
35 */
36
37 GLOBAL(boolean)
38 jpeg_start_decompress (j_decompress_ptr cinfo)
39 {
40 if (cinfo->global_state == DSTATE_READY) {
41 /* First call: initialize master control, select active modules */
42 jinit_master_decompress(cinfo);
43 if (cinfo->buffered_image) {
44 /* No more work here; expecting jpeg_start_output next */
45 cinfo->global_state = DSTATE_BUFIMAGE;
46 return TRUE;
47 }
48 cinfo->global_state = DSTATE_PRELOAD;
49 }
50 if (cinfo->global_state == DSTATE_PRELOAD) {
51 /* If file has multiple scans, absorb them all into the coef buffer */
52 if (cinfo->inputctl->has_multiple_scans) {
53 #ifdef D_MULTISCAN_FILES_SUPPORTED
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 FALSE;
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 /* jdmaster underestimated number of scans; ratchet up one scan */
70 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
71 }
72 }
73 }
74 #else
75 ERREXIT(cinfo, JERR_NOT_COMPILED);
76 #endif /* D_MULTISCAN_FILES_SUPPORTED */
77 }
78 cinfo->output_scan_number = cinfo->input_scan_number;
79 } else if (cinfo->global_state != DSTATE_PRESCAN)
80 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
81 /* Perform any dummy output passes, and set up for the final pass */
82 return output_pass_setup(cinfo);
83 }
84
85
86 /*
87 * Set up for an output pass, and perform any dummy pass(es) needed.
88 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
89 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
90 * Exit: If done, returns TRUE and sets global_state for proper output mode.
91 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
92 */
93
94 LOCAL(boolean)
95 output_pass_setup (j_decompress_ptr cinfo)
96 {
97 if (cinfo->global_state != DSTATE_PRESCAN) {
98 /* First call: do pass setup */
99 (*cinfo->master->prepare_for_output_pass) (cinfo);
100 cinfo->output_scanline = 0;
101 cinfo->global_state = DSTATE_PRESCAN;
102 }
103 /* Loop over any required dummy passes */
104 while (cinfo->master->is_dummy_pass) {
105 #ifdef QUANT_2PASS_SUPPORTED
106 /* Crank through the dummy pass */
107 while (cinfo->output_scanline < cinfo->output_height) {
108 JDIMENSION last_scanline;
109 /* Call progress monitor hook if present */
110 if (cinfo->progress != NULL) {
111 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
112 cinfo->progress->pass_limit = (long) cinfo->output_height;
113 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
114 }
115 /* Process some data */
116 last_scanline = cinfo->output_scanline;
117 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
118 &cinfo->output_scanline, (JDIMENSION) 0);
119 if (cinfo->output_scanline == last_scanline)
120 return FALSE; /* No progress made, must suspend */
121 }
122 /* Finish up dummy pass, and set up for another one */
123 (*cinfo->master->finish_output_pass) (cinfo);
124 (*cinfo->master->prepare_for_output_pass) (cinfo);
125 cinfo->output_scanline = 0;
126 #else
127 ERREXIT(cinfo, JERR_NOT_COMPILED);
128 #endif /* QUANT_2PASS_SUPPORTED */
129 }
130 /* Ready for application to drive output pass through
131 * jpeg_read_scanlines or jpeg_read_raw_data.
132 */
133 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
134 return TRUE;
135 }
136
137
138 /*
139 * Read some scanlines of data from the JPEG decompressor.
140 *
141 * The return value will be the number of lines actually read.
142 * This may be less than the number requested in several cases,
143 * including bottom of image, data source suspension, and operating
144 * modes that emit multiple scanlines at a time.
145 *
146 * Note: we warn about excess calls to jpeg_read_scanlines() since
147 * this likely signals an application programmer error. However,
148 * an oversize buffer (max_lines > scanlines remaining) is not an error.
149 */
150
151 GLOBAL(JDIMENSION)
152 jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
153 JDIMENSION max_lines)
154 {
155 JDIMENSION row_ctr;
156
157 if (cinfo->global_state != DSTATE_SCANNING)
158 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
159 if (cinfo->output_scanline >= cinfo->output_height) {
160 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
161 return 0;
162 }
163
164 /* Call progress monitor hook if present */
165 if (cinfo->progress != NULL) {
166 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
167 cinfo->progress->pass_limit = (long) cinfo->output_height;
168 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
169 }
170
171 /* Process some data */
172 row_ctr = 0;
173 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
174 cinfo->output_scanline += row_ctr;
175 return row_ctr;
176 }
177
178
179 /*
180 * Alternate entry point to read raw data.
181 * Processes exactly one iMCU row per call, unless suspended.
182 */
183
184 GLOBAL(JDIMENSION)
185 jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
186 JDIMENSION max_lines)
187 {
188 JDIMENSION lines_per_iMCU_row;
189
190 if (cinfo->global_state != DSTATE_RAW_OK)
191 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
192 if (cinfo->output_scanline >= cinfo->output_height) {
193 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
194 return 0;
195 }
196
197 /* Call progress monitor hook if present */
198 if (cinfo->progress != NULL) {
199 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
200 cinfo->progress->pass_limit = (long) cinfo->output_height;
201 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
202 }
203
204 /* Verify that at least one iMCU row can be returned. */
205 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
206 if (max_lines < lines_per_iMCU_row)
207 ERREXIT(cinfo, JERR_BUFFER_SIZE);
208
209 /* Decompress directly into user's buffer. */
210 if (! (*cinfo->coef->decompress_data) (cinfo, data))
211 return 0; /* suspension forced, can do nothing more */
212
213 /* OK, we processed one iMCU row. */
214 cinfo->output_scanline += lines_per_iMCU_row;
215 return lines_per_iMCU_row;
216 }
217
218
219 /* Additional entry points for buffered-image mode. */
220
221 #ifdef D_MULTISCAN_FILES_SUPPORTED
222
223 /*
224 * Initialize for an output pass in buffered-image mode.
225 */
226
227 GLOBAL(boolean)
228 jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
229 {
230 if (cinfo->global_state != DSTATE_BUFIMAGE &&
231 cinfo->global_state != DSTATE_PRESCAN)
232 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
233 /* Limit scan number to valid range */
234 if (scan_number <= 0)
235 scan_number = 1;
236 if (cinfo->inputctl->eoi_reached &&
237 scan_number > cinfo->input_scan_number)
238 scan_number = cinfo->input_scan_number;
239 cinfo->output_scan_number = scan_number;
240 /* Perform any dummy output passes, and set up for the real pass */
241 return output_pass_setup(cinfo);
242 }
243
244
245 /*
246 * Finish up after an output pass in buffered-image mode.
247 *
248 * Returns FALSE if suspended. The return value need be inspected only if
249 * a suspending data source is used.
250 */
251
252 GLOBAL(boolean)
253 jpeg_finish_output (j_decompress_ptr cinfo)
254 {
255 if ((cinfo->global_state == DSTATE_SCANNING ||
256 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
257 /* Terminate this pass. */
258 /* We do not require the whole pass to have been completed. */
259 (*cinfo->master->finish_output_pass) (cinfo);
260 cinfo->global_state = DSTATE_BUFPOST;
261 } else if (cinfo->global_state != DSTATE_BUFPOST) {
262 /* BUFPOST = repeat call after a suspension, anything else is error */
263 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
264 }
265 /* Read markers looking for SOS or EOI */
266 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
267 ! cinfo->inputctl->eoi_reached) {
268 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
269 return FALSE; /* Suspend, come back later */
270 }
271 cinfo->global_state = DSTATE_BUFIMAGE;
272 return TRUE;
273 }
274
275 #endif /* D_MULTISCAN_FILES_SUPPORTED */