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1 /* |
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2 * jdapimin.c |
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3 * |
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4 * Copyright (C) 1994-1998, 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 decompression half |
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9 * of the JPEG library. These are the "minimum" API routines that may be |
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10 * needed in either the normal full-decompression case or the |
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11 * transcoding-only case. |
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12 * |
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13 * Most of the routines intended to be called directly by an application |
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14 * are in this file or in jdapistd.c. But also see jcomapi.c for routines |
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15 * shared by compression and decompression, and jdtrans.c for the transcoding |
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16 * case. |
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17 */ |
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18 |
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19 #define JPEG_INTERNALS |
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20 #include "jinclude.h" |
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21 #include "jpeglib.h" |
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22 |
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23 |
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24 /* |
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25 * Initialization of a JPEG decompression object. |
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26 * The error manager must already be set up (in case memory manager fails). |
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27 */ |
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28 |
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29 GLOBAL(void) |
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30 jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize) |
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31 { |
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32 int i; |
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33 |
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34 /* Guard against version mismatches between library and caller. */ |
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35 cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */ |
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36 if (version != JPEG_LIB_VERSION) |
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37 ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version); |
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38 if (structsize != SIZEOF(struct jpeg_decompress_struct)) |
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39 ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE, |
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40 (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize); |
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41 |
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42 /* For debugging purposes, we zero the whole master structure. |
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43 * But the application has already set the err pointer, and may have set |
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44 * client_data, so we have to save and restore those fields. |
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45 * Note: if application hasn't set client_data, tools like Purify may |
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46 * complain here. |
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47 */ |
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48 { |
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49 struct jpeg_error_mgr * err = cinfo->err; |
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50 void * client_data = cinfo->client_data; /* ignore Purify complaint here */ |
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51 MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct)); |
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52 cinfo->err = err; |
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53 cinfo->client_data = client_data; |
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54 } |
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55 cinfo->is_decompressor = TRUE; |
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56 |
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57 /* Initialize a memory manager instance for this object */ |
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58 jinit_memory_mgr((j_common_ptr) cinfo); |
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59 |
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60 /* Zero out pointers to permanent structures. */ |
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61 cinfo->progress = NULL; |
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62 cinfo->src = NULL; |
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63 |
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64 for (i = 0; i < NUM_QUANT_TBLS; i++) |
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65 cinfo->quant_tbl_ptrs[i] = NULL; |
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66 |
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67 for (i = 0; i < NUM_HUFF_TBLS; i++) { |
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68 cinfo->dc_huff_tbl_ptrs[i] = NULL; |
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69 cinfo->ac_huff_tbl_ptrs[i] = NULL; |
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70 } |
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71 |
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72 /* Initialize marker processor so application can override methods |
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73 * for COM, APPn markers before calling jpeg_read_header. |
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74 */ |
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75 cinfo->marker_list = NULL; |
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76 jinit_marker_reader(cinfo); |
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77 |
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78 /* And initialize the overall input controller. */ |
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79 jinit_input_controller(cinfo); |
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80 |
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81 /* OK, I'm ready */ |
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82 cinfo->global_state = DSTATE_START; |
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83 } |
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84 |
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85 |
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86 /* |
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87 * Destruction of a JPEG decompression object |
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88 */ |
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89 |
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90 GLOBAL(void) |
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91 jpeg_destroy_decompress (j_decompress_ptr cinfo) |
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92 { |
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93 jpeg_destroy((j_common_ptr) cinfo); /* use common routine */ |
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94 } |
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95 |
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96 |
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97 /* |
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98 * Abort processing of a JPEG decompression operation, |
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99 * but don't destroy the object itself. |
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100 */ |
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101 |
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102 GLOBAL(void) |
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103 jpeg_abort_decompress (j_decompress_ptr cinfo) |
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104 { |
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105 jpeg_abort((j_common_ptr) cinfo); /* use common routine */ |
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106 } |
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107 |
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108 |
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109 /* |
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110 * Set default decompression parameters. |
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111 */ |
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112 |
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113 LOCAL(void) |
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114 default_decompress_parms (j_decompress_ptr cinfo) |
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115 { |
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116 /* Guess the input colorspace, and set output colorspace accordingly. */ |
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117 /* (Wish JPEG committee had provided a real way to specify this...) */ |
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118 /* Note application may override our guesses. */ |
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119 switch (cinfo->num_components) { |
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120 case 1: |
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121 cinfo->jpeg_color_space = JCS_GRAYSCALE; |
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122 cinfo->out_color_space = JCS_GRAYSCALE; |
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123 break; |
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124 |
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125 case 3: |
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126 if (cinfo->saw_JFIF_marker) { |
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127 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */ |
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128 } else if (cinfo->saw_Adobe_marker) { |
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129 switch (cinfo->Adobe_transform) { |
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130 case 0: |
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131 cinfo->jpeg_color_space = JCS_RGB; |
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132 break; |
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133 case 1: |
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134 cinfo->jpeg_color_space = JCS_YCbCr; |
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135 break; |
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136 default: |
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137 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform); |
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138 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */ |
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139 break; |
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140 } |
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141 } else { |
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142 /* Saw no special markers, try to guess from the component IDs */ |
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143 int cid0 = cinfo->comp_info[0].component_id; |
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144 int cid1 = cinfo->comp_info[1].component_id; |
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145 int cid2 = cinfo->comp_info[2].component_id; |
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146 |
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147 if (cid0 == 1 && cid1 == 2 && cid2 == 3) |
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148 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */ |
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149 else if (cid0 == 82 && cid1 == 71 && cid2 == 66) |
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150 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */ |
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151 else { |
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152 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2); |
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153 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */ |
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154 } |
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155 } |
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156 /* Always guess RGB is proper output colorspace. */ |
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157 cinfo->out_color_space = JCS_RGB; |
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158 break; |
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159 |
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160 case 4: |
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161 if (cinfo->saw_Adobe_marker) { |
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162 switch (cinfo->Adobe_transform) { |
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163 case 0: |
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164 cinfo->jpeg_color_space = JCS_CMYK; |
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165 break; |
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166 case 2: |
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167 cinfo->jpeg_color_space = JCS_YCCK; |
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168 break; |
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169 default: |
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170 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform); |
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171 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */ |
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172 break; |
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173 } |
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174 } else { |
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175 /* No special markers, assume straight CMYK. */ |
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176 cinfo->jpeg_color_space = JCS_CMYK; |
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177 } |
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178 cinfo->out_color_space = JCS_CMYK; |
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179 break; |
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180 |
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181 default: |
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182 cinfo->jpeg_color_space = JCS_UNKNOWN; |
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183 cinfo->out_color_space = JCS_UNKNOWN; |
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184 break; |
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185 } |
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186 |
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187 /* Set defaults for other decompression parameters. */ |
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188 cinfo->scale_num = 1; /* 1:1 scaling */ |
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189 cinfo->scale_denom = 1; |
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190 cinfo->output_gamma = 1.0; |
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191 cinfo->buffered_image = FALSE; |
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192 cinfo->raw_data_out = FALSE; |
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193 cinfo->dct_method = JDCT_DEFAULT; |
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194 cinfo->do_fancy_upsampling = TRUE; |
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195 cinfo->do_block_smoothing = TRUE; |
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196 cinfo->quantize_colors = FALSE; |
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197 /* We set these in case application only sets quantize_colors. */ |
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198 cinfo->dither_mode = JDITHER_FS; |
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199 #ifdef QUANT_2PASS_SUPPORTED |
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200 cinfo->two_pass_quantize = TRUE; |
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201 #else |
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202 cinfo->two_pass_quantize = FALSE; |
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203 #endif |
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204 cinfo->desired_number_of_colors = 256; |
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205 cinfo->colormap = NULL; |
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206 /* Initialize for no mode change in buffered-image mode. */ |
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207 cinfo->enable_1pass_quant = FALSE; |
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208 cinfo->enable_external_quant = FALSE; |
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209 cinfo->enable_2pass_quant = FALSE; |
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210 } |
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211 |
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212 |
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213 /* |
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214 * Decompression startup: read start of JPEG datastream to see what's there. |
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215 * Need only initialize JPEG object and supply a data source before calling. |
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216 * |
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217 * This routine will read as far as the first SOS marker (ie, actual start of |
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218 * compressed data), and will save all tables and parameters in the JPEG |
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219 * object. It will also initialize the decompression parameters to default |
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220 * values, and finally return JPEG_HEADER_OK. On return, the application may |
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221 * adjust the decompression parameters and then call jpeg_start_decompress. |
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222 * (Or, if the application only wanted to determine the image parameters, |
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223 * the data need not be decompressed. In that case, call jpeg_abort or |
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224 * jpeg_destroy to release any temporary space.) |
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225 * If an abbreviated (tables only) datastream is presented, the routine will |
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226 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then |
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227 * re-use the JPEG object to read the abbreviated image datastream(s). |
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228 * It is unnecessary (but OK) to call jpeg_abort in this case. |
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229 * The JPEG_SUSPENDED return code only occurs if the data source module |
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230 * requests suspension of the decompressor. In this case the application |
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231 * should load more source data and then re-call jpeg_read_header to resume |
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232 * processing. |
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233 * If a non-suspending data source is used and require_image is TRUE, then the |
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234 * return code need not be inspected since only JPEG_HEADER_OK is possible. |
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235 * |
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236 * This routine is now just a front end to jpeg_consume_input, with some |
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237 * extra error checking. |
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238 */ |
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239 |
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240 GLOBAL(int) |
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241 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image) |
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242 { |
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243 int retcode; |
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244 |
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245 if (cinfo->global_state != DSTATE_START && |
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246 cinfo->global_state != DSTATE_INHEADER) |
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247 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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248 |
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249 retcode = jpeg_consume_input(cinfo); |
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250 |
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251 switch (retcode) { |
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252 case JPEG_REACHED_SOS: |
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253 retcode = JPEG_HEADER_OK; |
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254 break; |
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255 case JPEG_REACHED_EOI: |
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256 if (require_image) /* Complain if application wanted an image */ |
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257 ERREXIT(cinfo, JERR_NO_IMAGE); |
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258 /* Reset to start state; it would be safer to require the application to |
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259 * call jpeg_abort, but we can't change it now for compatibility reasons. |
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260 * A side effect is to free any temporary memory (there shouldn't be any). |
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261 */ |
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262 jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */ |
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263 retcode = JPEG_HEADER_TABLES_ONLY; |
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264 break; |
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265 case JPEG_SUSPENDED: |
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266 /* no work */ |
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267 break; |
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268 } |
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269 |
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270 return retcode; |
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271 } |
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272 |
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273 |
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274 /* |
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275 * Consume data in advance of what the decompressor requires. |
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276 * This can be called at any time once the decompressor object has |
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277 * been created and a data source has been set up. |
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278 * |
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279 * This routine is essentially a state machine that handles a couple |
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280 * of critical state-transition actions, namely initial setup and |
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281 * transition from header scanning to ready-for-start_decompress. |
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282 * All the actual input is done via the input controller's consume_input |
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283 * method. |
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284 */ |
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285 |
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286 GLOBAL(int) |
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287 jpeg_consume_input (j_decompress_ptr cinfo) |
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288 { |
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289 int retcode = JPEG_SUSPENDED; |
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290 |
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291 /* NB: every possible DSTATE value should be listed in this switch */ |
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292 switch (cinfo->global_state) { |
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293 case DSTATE_START: |
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294 /* Start-of-datastream actions: reset appropriate modules */ |
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295 (*cinfo->inputctl->reset_input_controller) (cinfo); |
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296 /* Initialize application's data source module */ |
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297 (*cinfo->src->init_source) (cinfo); |
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298 cinfo->global_state = DSTATE_INHEADER; |
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299 /*FALLTHROUGH*/ |
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300 case DSTATE_INHEADER: |
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301 retcode = (*cinfo->inputctl->consume_input) (cinfo); |
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302 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */ |
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303 /* Set up default parameters based on header data */ |
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304 default_decompress_parms(cinfo); |
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305 /* Set global state: ready for start_decompress */ |
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306 cinfo->global_state = DSTATE_READY; |
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307 } |
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308 break; |
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309 case DSTATE_READY: |
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310 /* Can't advance past first SOS until start_decompress is called */ |
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311 retcode = JPEG_REACHED_SOS; |
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312 break; |
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313 case DSTATE_PRELOAD: |
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314 case DSTATE_PRESCAN: |
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315 case DSTATE_SCANNING: |
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316 case DSTATE_RAW_OK: |
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317 case DSTATE_BUFIMAGE: |
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318 case DSTATE_BUFPOST: |
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319 case DSTATE_STOPPING: |
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320 retcode = (*cinfo->inputctl->consume_input) (cinfo); |
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321 break; |
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322 default: |
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323 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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324 } |
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325 return retcode; |
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326 } |
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327 |
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328 |
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329 /* |
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330 * Have we finished reading the input file? |
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331 */ |
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332 |
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333 GLOBAL(boolean) |
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334 jpeg_input_complete (j_decompress_ptr cinfo) |
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335 { |
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336 /* Check for valid jpeg object */ |
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337 if (cinfo->global_state < DSTATE_START || |
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338 cinfo->global_state > DSTATE_STOPPING) |
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339 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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340 return cinfo->inputctl->eoi_reached; |
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341 } |
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342 |
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343 |
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344 /* |
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345 * Is there more than one scan? |
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346 */ |
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347 |
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348 GLOBAL(boolean) |
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349 jpeg_has_multiple_scans (j_decompress_ptr cinfo) |
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350 { |
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351 /* Only valid after jpeg_read_header completes */ |
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352 if (cinfo->global_state < DSTATE_READY || |
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353 cinfo->global_state > DSTATE_STOPPING) |
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354 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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355 return cinfo->inputctl->has_multiple_scans; |
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356 } |
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357 |
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358 |
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359 /* |
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360 * Finish JPEG decompression. |
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361 * |
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362 * This will normally just verify the file trailer and release temp storage. |
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363 * |
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364 * Returns FALSE if suspended. The return value need be inspected only if |
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365 * a suspending data source is used. |
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366 */ |
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367 |
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368 GLOBAL(boolean) |
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369 jpeg_finish_decompress (j_decompress_ptr cinfo) |
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370 { |
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371 if ((cinfo->global_state == DSTATE_SCANNING || |
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372 cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) { |
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373 /* Terminate final pass of non-buffered mode */ |
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374 if (cinfo->output_scanline < cinfo->output_height) |
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375 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA); |
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376 (*cinfo->master->finish_output_pass) (cinfo); |
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377 cinfo->global_state = DSTATE_STOPPING; |
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378 } else if (cinfo->global_state == DSTATE_BUFIMAGE) { |
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379 /* Finishing after a buffered-image operation */ |
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380 cinfo->global_state = DSTATE_STOPPING; |
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381 } else if (cinfo->global_state != DSTATE_STOPPING) { |
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382 /* STOPPING = repeat call after a suspension, anything else is error */ |
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383 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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384 } |
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385 /* Read until EOI */ |
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386 while (! cinfo->inputctl->eoi_reached) { |
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387 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) |
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388 return FALSE; /* Suspend, come back later */ |
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389 } |
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390 /* Do final cleanup */ |
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391 (*cinfo->src->term_source) (cinfo); |
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392 /* We can use jpeg_abort to release memory and reset global_state */ |
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393 jpeg_abort((j_common_ptr) cinfo); |
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394 return TRUE; |
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395 } |