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 file.
7 : *
8 : * This file contains application interface code for the compression half
9 : * of the JPEG library. These are the "standard" API routines that are
10 : * used in the normal full-compression case. They are not used by a
11 : * transcoding-only application. Note that if an application links in
12 : * jpeg_start_compress, it will end up linking in the entire compressor.
13 : * We thus must separate this file from jcapimin.c to avoid linking the
14 : * whole compression library into a transcoder.
15 : */
16 :
17 : #define JPEG_INTERNALS
18 : #include "jinclude.h"
19 : #include "jpeglib.h"
20 :
21 :
22 : /*
23 : * Compression initialization.
24 : * Before calling this, all parameters and a data destination must be set up.
25 : *
26 : * We require a write_all_tables parameter as a failsafe check when writing
27 : * multiple datastreams from the same compression object. Since prior runs
28 : * will have left all the tables marked sent_table=TRUE, a subsequent run
29 : * would emit an abbreviated stream (no tables) by default. This may be what
30 : * is wanted, but for safety's sake it should not be the default behavior:
31 : * programmers should have to make a deliberate choice to emit abbreviated
32 : * images. Therefore the documentation and examples should encourage people
33 : * to pass write_all_tables=TRUE; then it will take active thought to do the
34 : * wrong thing.
35 : */
36 :
37 : GLOBAL(void)
38 3 : jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
39 : {
40 3 : if (cinfo->global_state != CSTATE_START)
41 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
42 :
43 3 : if (write_all_tables)
44 3 : jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
45 :
46 : /* (Re)initialize error mgr and destination modules */
47 3 : (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
48 3 : (*cinfo->dest->init_destination) (cinfo);
49 : /* Perform master selection of active modules */
50 3 : jinit_compress_master(cinfo);
51 : /* Set up for the first pass */
52 3 : (*cinfo->master->prepare_for_pass) (cinfo);
53 : /* Ready for application to drive first pass through jpeg_write_scanlines
54 : * or jpeg_write_raw_data.
55 : */
56 3 : cinfo->next_scanline = 0;
57 3 : cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
58 3 : }
59 :
60 :
61 : /*
62 : * Write some scanlines of data to the JPEG compressor.
63 : *
64 : * The return value will be the number of lines actually written.
65 : * This should be less than the supplied num_lines only in case that
66 : * the data destination module has requested suspension of the compressor,
67 : * or if more than image_height scanlines are passed in.
68 : *
69 : * Note: we warn about excess calls to jpeg_write_scanlines() since
70 : * this likely signals an application programmer error. However,
71 : * excess scanlines passed in the last valid call are *silently* ignored,
72 : * so that the application need not adjust num_lines for end-of-image
73 : * when using a multiple-scanline buffer.
74 : */
75 :
76 : GLOBAL(JDIMENSION)
77 144 : jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
78 : JDIMENSION num_lines)
79 : {
80 : JDIMENSION row_ctr, rows_left;
81 :
82 144 : if (cinfo->global_state != CSTATE_SCANNING)
83 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
84 144 : if (cinfo->next_scanline >= cinfo->image_height)
85 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
86 :
87 : /* Call progress monitor hook if present */
88 144 : if (cinfo->progress != NULL) {
89 0 : cinfo->progress->pass_counter = (long) cinfo->next_scanline;
90 0 : cinfo->progress->pass_limit = (long) cinfo->image_height;
91 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
92 : }
93 :
94 : /* Give master control module another chance if this is first call to
95 : * jpeg_write_scanlines. This lets output of the frame/scan headers be
96 : * delayed so that application can write COM, etc, markers between
97 : * jpeg_start_compress and jpeg_write_scanlines.
98 : */
99 144 : if (cinfo->master->call_pass_startup)
100 3 : (*cinfo->master->pass_startup) (cinfo);
101 :
102 : /* Ignore any extra scanlines at bottom of image. */
103 144 : rows_left = cinfo->image_height - cinfo->next_scanline;
104 144 : if (num_lines > rows_left)
105 0 : num_lines = rows_left;
106 :
107 144 : row_ctr = 0;
108 144 : (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
109 144 : cinfo->next_scanline += row_ctr;
110 144 : return row_ctr;
111 : }
112 :
113 :
114 : /*
115 : * Alternate entry point to write raw data.
116 : * Processes exactly one iMCU row per call, unless suspended.
117 : */
118 :
119 : GLOBAL(JDIMENSION)
120 0 : jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
121 : JDIMENSION num_lines)
122 : {
123 : JDIMENSION lines_per_iMCU_row;
124 :
125 0 : if (cinfo->global_state != CSTATE_RAW_OK)
126 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
127 0 : if (cinfo->next_scanline >= cinfo->image_height) {
128 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
129 0 : return 0;
130 : }
131 :
132 : /* Call progress monitor hook if present */
133 0 : if (cinfo->progress != NULL) {
134 0 : cinfo->progress->pass_counter = (long) cinfo->next_scanline;
135 0 : cinfo->progress->pass_limit = (long) cinfo->image_height;
136 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
137 : }
138 :
139 : /* Give master control module another chance if this is first call to
140 : * jpeg_write_raw_data. This lets output of the frame/scan headers be
141 : * delayed so that application can write COM, etc, markers between
142 : * jpeg_start_compress and jpeg_write_raw_data.
143 : */
144 0 : if (cinfo->master->call_pass_startup)
145 0 : (*cinfo->master->pass_startup) (cinfo);
146 :
147 : /* Verify that at least one iMCU row has been passed. */
148 0 : lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;
149 0 : if (num_lines < lines_per_iMCU_row)
150 0 : ERREXIT(cinfo, JERR_BUFFER_SIZE);
151 :
152 : /* Directly compress the row. */
153 0 : if (! (*cinfo->coef->compress_data) (cinfo, data)) {
154 : /* If compressor did not consume the whole row, suspend processing. */
155 0 : return 0;
156 : }
157 :
158 : /* OK, we processed one iMCU row. */
159 0 : cinfo->next_scanline += lines_per_iMCU_row;
160 0 : return lines_per_iMCU_row;
161 : }
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