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6417 | ashmew2 | 1 | /* |
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 | |||
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 | |||
23 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
78 | /* And initialize the overall input controller. */ |
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79 | jinit_input_controller(cinfo); |
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80 | |||
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 | |||
85 | |||
86 | /* |
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87 | * Destruction of a JPEG decompression object |
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88 | */ |
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89 | |||
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 | |||
96 | |||
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 | |||
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 | |||
108 | |||
109 | /* |
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110 | * Set default decompression parameters. |
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111 | */ |
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112 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
212 | |||
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 | |||
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 | |||
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 | |||
249 | retcode = jpeg_consume_input(cinfo); |
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250 | |||
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 | |||
270 | return retcode; |
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271 | } |
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272 | |||
273 | |||
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 | |||
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 | |||
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 | |||
328 | |||
329 | /* |
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330 | * Have we finished reading the input file? |
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331 | */ |
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332 | |||
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 | |||
343 | |||
344 | /* |
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345 | * Is there more than one scan? |
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346 | */ |
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347 | |||
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 | |||
358 | |||
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 | |||
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 | }>>>>> |