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1 /* |
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2 * reserved comment block |
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3 * DO NOT REMOVE OR ALTER! |
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4 */ |
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5 /* |
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6 * jcapistd.c |
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7 * |
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8 * Copyright (C) 1994-1996, Thomas G. Lane. |
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9 * This file is part of the Independent JPEG Group's software. |
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10 * For conditions of distribution and use, see the accompanying README file. |
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11 * |
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12 * This file contains application interface code for the compression half |
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13 * of the JPEG library. These are the "standard" API routines that are |
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14 * used in the normal full-compression case. They are not used by a |
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15 * transcoding-only application. Note that if an application links in |
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16 * jpeg_start_compress, it will end up linking in the entire compressor. |
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17 * We thus must separate this file from jcapimin.c to avoid linking the |
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18 * whole compression library into a transcoder. |
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19 */ |
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20 |
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21 #define JPEG_INTERNALS |
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22 #include "jinclude.h" |
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23 #include "jpeglib.h" |
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24 |
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25 |
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26 /* |
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27 * Compression initialization. |
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28 * Before calling this, all parameters and a data destination must be set up. |
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29 * |
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30 * We require a write_all_tables parameter as a failsafe check when writing |
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31 * multiple datastreams from the same compression object. Since prior runs |
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32 * will have left all the tables marked sent_table=TRUE, a subsequent run |
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33 * would emit an abbreviated stream (no tables) by default. This may be what |
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34 * is wanted, but for safety's sake it should not be the default behavior: |
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35 * programmers should have to make a deliberate choice to emit abbreviated |
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36 * images. Therefore the documentation and examples should encourage people |
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37 * to pass write_all_tables=TRUE; then it will take active thought to do the |
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38 * wrong thing. |
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39 */ |
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40 |
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41 GLOBAL(void) |
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42 jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables) |
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43 { |
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44 if (cinfo->global_state != CSTATE_START) |
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45 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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46 |
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47 if (write_all_tables) |
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48 jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */ |
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49 |
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50 /* (Re)initialize error mgr and destination modules */ |
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51 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); |
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52 (*cinfo->dest->init_destination) (cinfo); |
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53 /* Perform master selection of active modules */ |
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54 jinit_compress_master(cinfo); |
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55 /* Set up for the first pass */ |
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56 (*cinfo->master->prepare_for_pass) (cinfo); |
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57 /* Ready for application to drive first pass through jpeg_write_scanlines |
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58 * or jpeg_write_raw_data. |
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59 */ |
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60 cinfo->next_scanline = 0; |
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61 cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING); |
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62 } |
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63 |
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64 |
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65 /* |
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66 * Write some scanlines of data to the JPEG compressor. |
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67 * |
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68 * The return value will be the number of lines actually written. |
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69 * This should be less than the supplied num_lines only in case that |
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70 * the data destination module has requested suspension of the compressor, |
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71 * or if more than image_height scanlines are passed in. |
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72 * |
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73 * Note: we warn about excess calls to jpeg_write_scanlines() since |
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74 * this likely signals an application programmer error. However, |
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75 * excess scanlines passed in the last valid call are *silently* ignored, |
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76 * so that the application need not adjust num_lines for end-of-image |
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77 * when using a multiple-scanline buffer. |
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78 */ |
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79 |
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80 GLOBAL(JDIMENSION) |
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81 jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines, |
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82 JDIMENSION num_lines) |
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83 { |
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84 JDIMENSION row_ctr, rows_left; |
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85 |
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86 if (cinfo->global_state != CSTATE_SCANNING) |
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87 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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88 if (cinfo->next_scanline >= cinfo->image_height) |
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89 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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90 |
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91 /* Call progress monitor hook if present */ |
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92 if (cinfo->progress != NULL) { |
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93 cinfo->progress->pass_counter = (long) cinfo->next_scanline; |
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94 cinfo->progress->pass_limit = (long) cinfo->image_height; |
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95 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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96 } |
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97 |
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98 /* Give master control module another chance if this is first call to |
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99 * jpeg_write_scanlines. This lets output of the frame/scan headers be |
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100 * delayed so that application can write COM, etc, markers between |
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101 * jpeg_start_compress and jpeg_write_scanlines. |
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102 */ |
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103 if (cinfo->master->call_pass_startup) |
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104 (*cinfo->master->pass_startup) (cinfo); |
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105 |
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106 /* Ignore any extra scanlines at bottom of image. */ |
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107 rows_left = cinfo->image_height - cinfo->next_scanline; |
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108 if (num_lines > rows_left) |
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109 num_lines = rows_left; |
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110 |
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111 row_ctr = 0; |
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112 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines); |
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113 cinfo->next_scanline += row_ctr; |
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114 return row_ctr; |
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115 } |
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116 |
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117 |
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118 /* |
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119 * Alternate entry point to write raw data. |
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120 * Processes exactly one iMCU row per call, unless suspended. |
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121 */ |
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122 |
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123 GLOBAL(JDIMENSION) |
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124 jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data, |
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125 JDIMENSION num_lines) |
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126 { |
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127 JDIMENSION lines_per_iMCU_row; |
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128 |
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129 if (cinfo->global_state != CSTATE_RAW_OK) |
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130 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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131 if (cinfo->next_scanline >= cinfo->image_height) { |
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132 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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133 return 0; |
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134 } |
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135 |
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136 /* Call progress monitor hook if present */ |
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137 if (cinfo->progress != NULL) { |
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138 cinfo->progress->pass_counter = (long) cinfo->next_scanline; |
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139 cinfo->progress->pass_limit = (long) cinfo->image_height; |
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140 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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141 } |
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142 |
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143 /* Give master control module another chance if this is first call to |
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144 * jpeg_write_raw_data. This lets output of the frame/scan headers be |
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145 * delayed so that application can write COM, etc, markers between |
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146 * jpeg_start_compress and jpeg_write_raw_data. |
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147 */ |
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148 if (cinfo->master->call_pass_startup) |
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149 (*cinfo->master->pass_startup) (cinfo); |
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150 |
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151 /* Verify that at least one iMCU row has been passed. */ |
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152 lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; |
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153 if (num_lines < lines_per_iMCU_row) |
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154 ERREXIT(cinfo, JERR_BUFFER_SIZE); |
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155 |
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156 /* Directly compress the row. */ |
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157 if (! (*cinfo->coef->compress_data) (cinfo, data)) { |
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158 /* If compressor did not consume the whole row, suspend processing. */ |
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159 return 0; |
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160 } |
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161 |
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162 /* OK, we processed one iMCU row. */ |
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163 cinfo->next_scanline += lines_per_iMCU_row; |
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164 return lines_per_iMCU_row; |
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165 } |