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1 /*
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2 * jcapistd.c
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3 *
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4 * Copyright (C) 1994-1996, Thomas G. Lane.
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5 * This file is part of the Independent JPEG Group's software.
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6 * For conditions of distribution and use, see the accompanying README file.
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7 *
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8 * This file contains application interface code for the compression half
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9 * of the JPEG library. These are the "standard" API routines that are
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10 * used in the normal full-compression case. They are not used by a
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11 * transcoding-only application. Note that if an application links in
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12 * jpeg_start_compress, it will end up linking in the entire compressor.
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13 * We thus must separate this file from jcapimin.c to avoid linking the
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14 * whole compression library into a transcoder.
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15 */
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16
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17 #define JPEG_INTERNALS
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18 #include "jinclude.h"
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19 #include "jpeglib.h"
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20
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21
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22 /*
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23 * Compression initialization.
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24 * Before calling this, all parameters and a data destination must be set up.
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25 *
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26 * We require a write_all_tables parameter as a failsafe check when writing
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27 * multiple datastreams from the same compression object. Since prior runs
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28 * will have left all the tables marked sent_table=TRUE, a subsequent run
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29 * would emit an abbreviated stream (no tables) by default. This may be what
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30 * is wanted, but for safety's sake it should not be the default behavior:
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31 * programmers should have to make a deliberate choice to emit abbreviated
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32 * images. Therefore the documentation and examples should encourage people
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33 * to pass write_all_tables=TRUE; then it will take active thought to do the
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34 * wrong thing.
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35 */
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36
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37 GLOBAL(void)
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38 jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
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39 {
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40 if (cinfo->global_state != CSTATE_START)
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41 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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42
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43 if (write_all_tables)
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44 jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
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45
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46 /* (Re)initialize error mgr and destination modules */
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47 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
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48 (*cinfo->dest->init_destination) (cinfo);
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49 /* Perform master selection of active modules */
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50 jinit_compress_master(cinfo);
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51 /* Set up for the first pass */
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52 (*cinfo->master->prepare_for_pass) (cinfo);
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53 /* Ready for application to drive first pass through jpeg_write_scanlines
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54 * or jpeg_write_raw_data.
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55 */
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56 cinfo->next_scanline = 0;
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57 cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
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58 }
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59
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60
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61 /*
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62 * Write some scanlines of data to the JPEG compressor.
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63 *
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64 * The return value will be the number of lines actually written.
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65 * This should be less than the supplied num_lines only in case that
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66 * the data destination module has requested suspension of the compressor,
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67 * or if more than image_height scanlines are passed in.
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68 *
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69 * Note: we warn about excess calls to jpeg_write_scanlines() since
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70 * this likely signals an application programmer error. However,
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71 * excess scanlines passed in the last valid call are *silently* ignored,
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72 * so that the application need not adjust num_lines for end-of-image
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73 * when using a multiple-scanline buffer.
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74 */
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75
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76 GLOBAL(JDIMENSION)
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77 jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
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78 JDIMENSION num_lines)
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79 {
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80 JDIMENSION row_ctr, rows_left;
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81
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82 if (cinfo->global_state != CSTATE_SCANNING)
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83 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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84 if (cinfo->next_scanline >= cinfo->image_height)
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85 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
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86
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87 /* Call progress monitor hook if present */
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88 if (cinfo->progress != NULL) {
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89 cinfo->progress->pass_counter = (long) cinfo->next_scanline;
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90 cinfo->progress->pass_limit = (long) cinfo->image_height;
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91 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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92 }
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93
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94 /* Give master control module another chance if this is first call to
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95 * jpeg_write_scanlines. This lets output of the frame/scan headers be
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96 * delayed so that application can write COM, etc, markers between
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97 * jpeg_start_compress and jpeg_write_scanlines.
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98 */
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99 if (cinfo->master->call_pass_startup)
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100 (*cinfo->master->pass_startup) (cinfo);
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101
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102 /* Ignore any extra scanlines at bottom of image. */
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103 rows_left = cinfo->image_height - cinfo->next_scanline;
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104 if (num_lines > rows_left)
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105 num_lines = rows_left;
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106
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107 row_ctr = 0;
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108 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
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109 cinfo->next_scanline += row_ctr;
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110 return row_ctr;
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111 }
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112
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113
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114 /*
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115 * Alternate entry point to write raw data.
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116 * Processes exactly one iMCU row per call, unless suspended.
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117 */
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118
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119 GLOBAL(JDIMENSION)
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120 jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
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121 JDIMENSION num_lines)
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122 {
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123 JDIMENSION lines_per_iMCU_row;
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124
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125 if (cinfo->global_state != CSTATE_RAW_OK)
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126 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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127 if (cinfo->next_scanline >= cinfo->image_height) {
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128 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
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129 return 0;
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130 }
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131
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132 /* Call progress monitor hook if present */
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133 if (cinfo->progress != NULL) {
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134 cinfo->progress->pass_counter = (long) cinfo->next_scanline;
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135 cinfo->progress->pass_limit = (long) cinfo->image_height;
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136 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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137 }
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138
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139 /* Give master control module another chance if this is first call to
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140 * jpeg_write_raw_data. This lets output of the frame/scan headers be
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141 * delayed so that application can write COM, etc, markers between
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142 * jpeg_start_compress and jpeg_write_raw_data.
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143 */
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144 if (cinfo->master->call_pass_startup)
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145 (*cinfo->master->pass_startup) (cinfo);
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146
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147 /* Verify that at least one iMCU row has been passed. */
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148 lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;
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149 if (num_lines < lines_per_iMCU_row)
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150 ERREXIT(cinfo, JERR_BUFFER_SIZE);
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151
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152 /* Directly compress the row. */
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153 if (! (*cinfo->coef->compress_data) (cinfo, data)) {
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154 /* If compressor did not consume the whole row, suspend processing. */
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155 return 0;
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156 }
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157
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158 /* OK, we processed one iMCU row. */
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159 cinfo->next_scanline += lines_per_iMCU_row;
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160 return lines_per_iMCU_row;
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161 }
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