00001 #include "jpegSize.h"
00002
00003 #include <stdio.h>
00004
00005
00006
00007
00008
00009
00010
00011
00012
00013
00014
00015
00016
00017
00018 #define NEXTBYTE() getc(infile)
00019
00020
00021
00022
00023
00024
00025
00026 #define M_SOF0 0xC0
00027 #define M_SOF1 0xC1
00028 #define M_SOF2 0xC2
00029 #define M_SOF3 0xC3
00030 #define M_SOF5 0xC5
00031 #define M_SOF6 0xC6
00032 #define M_SOF7 0xC7
00033 #define M_SOF9 0xC9
00034 #define M_SOF10 0xCA
00035 #define M_SOF11 0xCB
00036 #define M_SOF13 0xCD
00037 #define M_SOF14 0xCE
00038 #define M_SOF15 0xCF
00039 #define M_SOI 0xD8
00040 #define M_EOI 0xD9
00041 #define M_SOS 0xDA
00042 #define M_APP0 0xE0
00043 #define M_APP12 0xEC
00044 #define M_COM 0xFE
00045
00046 #ifdef DONT_USE_B_MODE
00047 #define READ_BINARY "r"
00048 #else
00049 #ifdef VMS
00050 #define READ_BINARY "rb", "ctx=stm"
00051 #else
00052 #define READ_BINARY "rb"
00053 #endif
00054 #endif
00055
00056 FILE * infile;
00057
00058 bool process_SOFn (int& width, int& height);
00059 bool skip_variable ();
00060 bool read_1_byte (int* res);
00061 bool read_2_bytes (unsigned int* res);
00062 bool first_marker (int* res);
00063 bool next_marker (int* res);
00064
00065 bool getJPEGSize( const char* filename, int& width, int& height )
00066 {
00067
00068 if ((infile = fopen(filename, READ_BINARY)) == NULL)
00069 return false;
00070
00071
00072
00073 int marker;
00074
00075
00076 if (!first_marker(&marker))
00077 {
00078 fclose(infile);
00079 return false;
00080 }
00081
00082
00083 for (;;)
00084 {
00085 if(!next_marker(&marker))
00086 {
00087 fclose(infile);
00088 return false;
00089 }
00090
00091 switch (marker)
00092 {
00093
00094
00095
00096 case M_SOF0:
00097 case M_SOF1:
00098 case M_SOF2:
00099 case M_SOF3:
00100 case M_SOF5:
00101 case M_SOF6:
00102 case M_SOF7:
00103 case M_SOF9:
00104 case M_SOF10:
00105 case M_SOF11:
00106 case M_SOF13:
00107 case M_SOF14:
00108 case M_SOF15:
00109 if(!process_SOFn(width, height))
00110 {
00111 fclose(infile);
00112 return false;
00113 }
00114 else
00115 {
00116 fclose(infile);
00117 return true;
00118 }
00119 case M_SOS:
00120 {
00121 fclose(infile);
00122 return false;
00123 }
00124 case M_EOI:
00125 {
00126 fclose(infile);
00127 return false;
00128 }
00129 default:
00130 skip_variable();
00131 break;
00132 }
00133 }
00134
00135
00136
00137 return false;
00138
00139 }
00140
00141
00142
00143
00144
00145
00146
00147
00148
00149 bool first_marker (int* res)
00150 {
00151 int c1, c2;
00152 c1 = NEXTBYTE();
00153 c2 = NEXTBYTE();
00154 if (c1 != 0xFF || c2 != M_SOI)
00155 return false;
00156 else
00157 {
00158 *res = c2;
00159 return true;
00160 }
00161 }
00162
00163
00164
00165
00166
00167
00168
00169
00170
00171
00172 bool next_marker (int* res)
00173 {
00174 int c;
00175 int discarded_bytes = 0;
00176
00177
00178 if(!read_1_byte(&c))
00179 return false;
00180 while (c != 0xFF)
00181 {
00182 discarded_bytes++;
00183 if(!read_1_byte(&c))
00184 return false;
00185 }
00186
00187
00188
00189 do
00190 {
00191 if(!read_1_byte(&c))
00192 return false;
00193 } while (c == 0xFF);
00194
00195
00196
00197 *res = c;
00198 return true;
00199 }
00200
00201
00202 bool read_1_byte (int* res)
00203 {
00204 int c = NEXTBYTE();
00205 if (c == EOF)
00206 return false;
00207 else
00208 {
00209 *res = c;
00210 return true;
00211 }
00212 }
00213
00214
00215
00216 bool read_2_bytes (unsigned int* res)
00217 {
00218 int c1, c2;
00219 c1 = NEXTBYTE();
00220 if (c1 == EOF)
00221 return false;
00222 c2 = NEXTBYTE();
00223 if (c2 == EOF)
00224 return false;
00225 *res = (((unsigned int) c1) << 8) + ((unsigned int) c2);
00226 return true;
00227 }
00228
00229
00230
00231
00232
00233
00234
00235
00236
00237 bool skip_variable ()
00238
00239 {
00240 unsigned int length;
00241
00242
00243 if(!read_2_bytes(&length))
00244 return false;
00245
00246 if (length < 2)
00247 return false;
00248 length -= 2;
00249
00250 while (length > 0)
00251 {
00252 int tmp;
00253 if(!read_1_byte(&tmp))
00254 return false;
00255 length--;
00256 }
00257 return false;
00258 }
00259
00260
00261 bool process_SOFn (int& width, int& height)
00262 {
00263 unsigned int length;
00264 unsigned int image_height, image_width;
00265 int data_precision;
00266
00267 if(!read_2_bytes(&length) ||
00268 !read_1_byte(&data_precision) ||
00269 !read_2_bytes(&image_height) ||
00270 !read_2_bytes(&image_width) )
00271 return false;
00272
00273 width = (int) image_width;
00274 height = (int) image_height;
00275 return true;
00276 }