Line data Source code
1 : /*
2 : * jcapistd.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.ijg
7 : * file.
8 : *
9 : * This file contains application interface code for the compression half
10 : * of the JPEG library. These are the "standard" API routines that are
11 : * used in the normal full-compression case. They are not used by a
12 : * transcoding-only application. Note that if an application links in
13 : * jpeg_start_compress, it will end up linking in the entire compressor.
14 : * We thus must separate this file from jcapimin.c to avoid linking the
15 : * whole compression library into a transcoder.
16 : */
17 :
18 : #define JPEG_INTERNALS
19 : #include "jinclude.h"
20 : #include "jpeglib.h"
21 :
22 :
23 : /*
24 : * Compression initialization.
25 : * Before calling this, all parameters and a data destination must be set up.
26 : *
27 : * We require a write_all_tables parameter as a failsafe check when writing
28 : * multiple datastreams from the same compression object. Since prior runs
29 : * will have left all the tables marked sent_table=TRUE, a subsequent run
30 : * would emit an abbreviated stream (no tables) by default. This may be what
31 : * is wanted, but for safety's sake it should not be the default behavior:
32 : * programmers should have to make a deliberate choice to emit abbreviated
33 : * images. Therefore the documentation and examples should encourage people
34 : * to pass write_all_tables=TRUE; then it will take active thought to do the
35 : * wrong thing.
36 : */
37 :
38 : GLOBAL(void)
39 0 : jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
40 : {
41 0 : if (cinfo->global_state != CSTATE_START)
42 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
43 :
44 0 : if (write_all_tables)
45 0 : jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
46 :
47 : /* (Re)initialize error mgr and destination modules */
48 0 : (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
49 0 : (*cinfo->dest->init_destination) (cinfo);
50 : /* Perform master selection of active modules */
51 0 : jinit_compress_master(cinfo);
52 : /* Set up for the first pass */
53 0 : (*cinfo->master->prepare_for_pass) (cinfo);
54 : /* Ready for application to drive first pass through jpeg_write_scanlines
55 : * or jpeg_write_raw_data.
56 : */
57 0 : cinfo->next_scanline = 0;
58 0 : cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
59 0 : }
60 :
61 :
62 : /*
63 : * Write some scanlines of data to the JPEG compressor.
64 : *
65 : * The return value will be the number of lines actually written.
66 : * This should be less than the supplied num_lines only in case that
67 : * the data destination module has requested suspension of the compressor,
68 : * or if more than image_height scanlines are passed in.
69 : *
70 : * Note: we warn about excess calls to jpeg_write_scanlines() since
71 : * this likely signals an application programmer error. However,
72 : * excess scanlines passed in the last valid call are *silently* ignored,
73 : * so that the application need not adjust num_lines for end-of-image
74 : * when using a multiple-scanline buffer.
75 : */
76 :
77 : GLOBAL(JDIMENSION)
78 0 : jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
79 : JDIMENSION num_lines)
80 : {
81 : JDIMENSION row_ctr, rows_left;
82 :
83 0 : if (cinfo->global_state != CSTATE_SCANNING)
84 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
85 0 : if (cinfo->next_scanline >= cinfo->image_height)
86 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
87 :
88 : /* Call progress monitor hook if present */
89 0 : if (cinfo->progress != NULL) {
90 0 : cinfo->progress->pass_counter = (long) cinfo->next_scanline;
91 0 : cinfo->progress->pass_limit = (long) cinfo->image_height;
92 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
93 : }
94 :
95 : /* Give master control module another chance if this is first call to
96 : * jpeg_write_scanlines. This lets output of the frame/scan headers be
97 : * delayed so that application can write COM, etc, markers between
98 : * jpeg_start_compress and jpeg_write_scanlines.
99 : */
100 0 : if (cinfo->master->call_pass_startup)
101 0 : (*cinfo->master->pass_startup) (cinfo);
102 :
103 : /* Ignore any extra scanlines at bottom of image. */
104 0 : rows_left = cinfo->image_height - cinfo->next_scanline;
105 0 : if (num_lines > rows_left)
106 0 : num_lines = rows_left;
107 :
108 0 : row_ctr = 0;
109 0 : (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
110 0 : cinfo->next_scanline += row_ctr;
111 0 : return row_ctr;
112 : }
113 :
114 :
115 : /*
116 : * Alternate entry point to write raw data.
117 : * Processes exactly one iMCU row per call, unless suspended.
118 : */
119 :
120 : GLOBAL(JDIMENSION)
121 0 : jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
122 : JDIMENSION num_lines)
123 : {
124 : JDIMENSION lines_per_iMCU_row;
125 :
126 0 : if (cinfo->global_state != CSTATE_RAW_OK)
127 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
128 0 : if (cinfo->next_scanline >= cinfo->image_height) {
129 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
130 0 : return 0;
131 : }
132 :
133 : /* Call progress monitor hook if present */
134 0 : if (cinfo->progress != NULL) {
135 0 : cinfo->progress->pass_counter = (long) cinfo->next_scanline;
136 0 : cinfo->progress->pass_limit = (long) cinfo->image_height;
137 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
138 : }
139 :
140 : /* Give master control module another chance if this is first call to
141 : * jpeg_write_raw_data. This lets output of the frame/scan headers be
142 : * delayed so that application can write COM, etc, markers between
143 : * jpeg_start_compress and jpeg_write_raw_data.
144 : */
145 0 : if (cinfo->master->call_pass_startup)
146 0 : (*cinfo->master->pass_startup) (cinfo);
147 :
148 : /* Verify that at least one iMCU row has been passed. */
149 0 : lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;
150 0 : if (num_lines < lines_per_iMCU_row)
151 0 : ERREXIT(cinfo, JERR_BUFFER_SIZE);
152 :
153 : /* Directly compress the row. */
154 0 : if (! (*cinfo->coef->compress_data) (cinfo, data)) {
155 : /* If compressor did not consume the whole row, suspend processing. */
156 0 : return 0;
157 : }
158 :
159 : /* OK, we processed one iMCU row. */
160 0 : cinfo->next_scanline += lines_per_iMCU_row;
161 0 : return lines_per_iMCU_row;
162 : }
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