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6417 | ashmew2 | 1 | /* |
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 | |||
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 | |||
21 | |||
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 | |||
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 | |||
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 | |||
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 | |||
60 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
113 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | }> |