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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 } |