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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 | jpeg_start_compress (j_compress_ptr cinfo, wxjpeg_boolean write_all_tables) | |
39 | { | |
40 | if (cinfo->global_state != CSTATE_START) | |
41 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
42 | ||
43 | if (write_all_tables) | |
44 | jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */ | |
45 | ||
46 | /* (Re)initialize error mgr and destination modules */ | |
47 | (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); | |
48 | (*cinfo->dest->init_destination) (cinfo); | |
49 | /* Perform master selection of active modules */ | |
50 | jinit_compress_master(cinfo); | |
51 | /* Set up for the first pass */ | |
52 | (*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 | cinfo->next_scanline = 0; | |
57 | cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING); | |
58 | } | |
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 | jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines, | |
78 | JDIMENSION num_lines) | |
79 | { | |
80 | JDIMENSION row_ctr, rows_left; | |
81 | ||
82 | if (cinfo->global_state != CSTATE_SCANNING) | |
83 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
84 | if (cinfo->next_scanline >= cinfo->image_height) | |
85 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); | |
86 | ||
87 | /* Call progress monitor hook if present */ | |
88 | if (cinfo->progress != NULL) { | |
89 | cinfo->progress->pass_counter = (long) cinfo->next_scanline; | |
90 | cinfo->progress->pass_limit = (long) cinfo->image_height; | |
91 | (*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 | if (cinfo->master->call_pass_startup) | |
100 | (*cinfo->master->pass_startup) (cinfo); | |
101 | ||
102 | /* Ignore any extra scanlines at bottom of image. */ | |
103 | rows_left = cinfo->image_height - cinfo->next_scanline; | |
104 | if (num_lines > rows_left) | |
105 | num_lines = rows_left; | |
106 | ||
107 | row_ctr = 0; | |
108 | (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines); | |
109 | cinfo->next_scanline += row_ctr; | |
110 | 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 | jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data, | |
121 | JDIMENSION num_lines) | |
122 | { | |
123 | JDIMENSION lines_per_iMCU_row; | |
124 | ||
125 | if (cinfo->global_state != CSTATE_RAW_OK) | |
126 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
127 | if (cinfo->next_scanline >= cinfo->image_height) { | |
128 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); | |
129 | return 0; | |
130 | } | |
131 | ||
132 | /* Call progress monitor hook if present */ | |
133 | if (cinfo->progress != NULL) { | |
134 | cinfo->progress->pass_counter = (long) cinfo->next_scanline; | |
135 | cinfo->progress->pass_limit = (long) cinfo->image_height; | |
136 | (*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 | if (cinfo->master->call_pass_startup) | |
145 | (*cinfo->master->pass_startup) (cinfo); | |
146 | ||
147 | /* Verify that at least one iMCU row has been passed. */ | |
148 | lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; | |
149 | if (num_lines < lines_per_iMCU_row) | |
150 | ERREXIT(cinfo, JERR_BUFFER_SIZE); | |
151 | ||
152 | /* Directly compress the row. */ | |
153 | if (! (*cinfo->coef->compress_data) (cinfo, data)) { | |
154 | /* If compressor did not consume the whole row, suspend processing. */ | |
155 | return 0; | |
156 | } | |
157 | ||
158 | /* OK, we processed one iMCU row. */ | |
159 | cinfo->next_scanline += lines_per_iMCU_row; | |
160 | return lines_per_iMCU_row; | |
161 | } |