1 /**************************************************************************** 2 * 3 * fterrors.h 4 * 5 * FreeType error code handling (specification). 6 * 7 * Copyright (C) 1996-2022 by 8 * David Turner, Robert Wilhelm, and Werner Lemberg. 9 * 10 * This file is part of the FreeType project, and may only be used, 11 * modified, and distributed under the terms of the FreeType project 12 * license, LICENSE.TXT. By continuing to use, modify, or distribute 13 * this file you indicate that you have read the license and 14 * understand and accept it fully. 15 * 16 */ 17 18 19 /************************************************************************** 20 * 21 * @section: 22 * error_enumerations 23 * 24 * @title: 25 * Error Enumerations 26 * 27 * @abstract: 28 * How to handle errors and error strings. 29 * 30 * @description: 31 * The header file `fterrors.h` (which is automatically included by 32 * `freetype.h` defines the handling of FreeType's enumeration 33 * constants. It can also be used to generate error message strings 34 * with a small macro trick explained below. 35 * 36 * **Error Formats** 37 * 38 * The configuration macro `FT_CONFIG_OPTION_USE_MODULE_ERRORS` can be 39 * defined in `ftoption.h` in order to make the higher byte indicate the 40 * module where the error has happened (this is not compatible with 41 * standard builds of FreeType~2, however). See the file `ftmoderr.h` 42 * for more details. 43 * 44 * **Error Message Strings** 45 * 46 * Error definitions are set up with special macros that allow client 47 * applications to build a table of error message strings. The strings 48 * are not included in a normal build of FreeType~2 to save space (most 49 * client applications do not use them). 50 * 51 * To do so, you have to define the following macros before including 52 * this file. 53 * 54 * ``` 55 * FT_ERROR_START_LIST 56 * ``` 57 * 58 * This macro is called before anything else to define the start of the 59 * error list. It is followed by several `FT_ERROR_DEF` calls. 60 * 61 * ``` 62 * FT_ERROR_DEF( e, v, s ) 63 * ``` 64 * 65 * This macro is called to define one single error. 'e' is the error 66 * code identifier (e.g., `Invalid_Argument`), 'v' is the error's 67 * numerical value, and 's' is the corresponding error string. 68 * 69 * ``` 70 * FT_ERROR_END_LIST 71 * ``` 72 * 73 * This macro ends the list. 74 * 75 * Additionally, you have to undefine `FTERRORS_H_` before #including 76 * this file. 77 * 78 * Here is a simple example. 79 * 80 * ``` 81 * #undef FTERRORS_H_ 82 * #define FT_ERRORDEF( e, v, s ) { e, s }, 83 * #define FT_ERROR_START_LIST { 84 * #define FT_ERROR_END_LIST { 0, NULL } }; 85 * 86 * const struct 87 * { 88 * int err_code; 89 * const char* err_msg; 90 * } ft_errors[] = 91 * 92 * #include <freetype/fterrors.h> 93 * ``` 94 * 95 * An alternative to using an array is a switch statement. 96 * 97 * ``` 98 * #undef FTERRORS_H_ 99 * #define FT_ERROR_START_LIST switch ( error_code ) { 100 * #define FT_ERRORDEF( e, v, s ) case v: return s; 101 * #define FT_ERROR_END_LIST } 102 * ``` 103 * 104 * If you use `FT_CONFIG_OPTION_USE_MODULE_ERRORS`, `error_code` should 105 * be replaced with `FT_ERROR_BASE(error_code)` in the last example. 106 */ 107 108 /* */ 109 110 /* In previous FreeType versions we used `__FTERRORS_H__`. However, */ 111 /* using two successive underscores in a non-system symbol name */ 112 /* violates the C (and C++) standard, so it was changed to the */ 113 /* current form. In spite of this, we have to make */ 114 /* */ 115 /* ``` */ 116 /* #undefine __FTERRORS_H__ */ 117 /* ``` */ 118 /* */ 119 /* work for backward compatibility. */ 120 /* */ 121 #if !( defined( FTERRORS_H_ ) && defined ( __FTERRORS_H__ ) ) 122 #define FTERRORS_H_ 123 #define __FTERRORS_H__ 124 125 126 /* include module base error codes */ 127 #include <freetype/ftmoderr.h> 128 129 130 /*******************************************************************/ 131 /*******************************************************************/ 132 /***** *****/ 133 /***** SETUP MACROS *****/ 134 /***** *****/ 135 /*******************************************************************/ 136 /*******************************************************************/ 137 138 139 #undef FT_NEED_EXTERN_C 140 141 142 /* FT_ERR_PREFIX is used as a prefix for error identifiers. */ 143 /* By default, we use `FT_Err_`. */ 144 /* */ 145 #ifndef FT_ERR_PREFIX 146 #define FT_ERR_PREFIX FT_Err_ 147 #endif 148 149 150 /* FT_ERR_BASE is used as the base for module-specific errors. */ 151 /* */ 152 #ifdef FT_CONFIG_OPTION_USE_MODULE_ERRORS 153 154 #ifndef FT_ERR_BASE 155 #define FT_ERR_BASE FT_Mod_Err_Base 156 #endif 157 158 #else 159 160 #undef FT_ERR_BASE 161 #define FT_ERR_BASE 0 162 163 #endif /* FT_CONFIG_OPTION_USE_MODULE_ERRORS */ 164 165 166 /* If FT_ERRORDEF is not defined, we need to define a simple */ 167 /* enumeration type. */ 168 /* */ 169 #ifndef FT_ERRORDEF 170 171 #define FT_INCLUDE_ERR_PROTOS 172 173 #define FT_ERRORDEF( e, v, s ) e = v, 174 #define FT_ERROR_START_LIST enum { 175 #define FT_ERROR_END_LIST FT_ERR_CAT( FT_ERR_PREFIX, Max ) }; 176 177 #ifdef __cplusplus 178 #define FT_NEED_EXTERN_C 179 extern "C" { 180 #endif 181 182 #endif /* !FT_ERRORDEF */ 183 184 185 /* this macro is used to define an error */ 186 #define FT_ERRORDEF_( e, v, s ) \ 187 FT_ERRORDEF( FT_ERR_CAT( FT_ERR_PREFIX, e ), v + FT_ERR_BASE, s ) 188 189 /* this is only used for <module>_Err_Ok, which must be 0! */ 190 #define FT_NOERRORDEF_( e, v, s ) \ 191 FT_ERRORDEF( FT_ERR_CAT( FT_ERR_PREFIX, e ), v, s ) 192 193 194 #ifdef FT_ERROR_START_LIST 195 FT_ERROR_START_LIST 196 #endif 197 198 199 /* now include the error codes */ 200 #include <freetype/fterrdef.h> 201 202 203 #ifdef FT_ERROR_END_LIST 204 FT_ERROR_END_LIST 205 #endif 206 207 208 /*******************************************************************/ 209 /*******************************************************************/ 210 /***** *****/ 211 /***** SIMPLE CLEANUP *****/ 212 /***** *****/ 213 /*******************************************************************/ 214 /*******************************************************************/ 215 216 #ifdef FT_NEED_EXTERN_C 217 } 218 #endif 219 220 #undef FT_ERROR_START_LIST 221 #undef FT_ERROR_END_LIST 222 223 #undef FT_ERRORDEF 224 #undef FT_ERRORDEF_ 225 #undef FT_NOERRORDEF_ 226 227 #undef FT_NEED_EXTERN_C 228 #undef FT_ERR_BASE 229 230 /* FT_ERR_PREFIX is needed internally */ 231 #ifndef FT2_BUILD_LIBRARY 232 #undef FT_ERR_PREFIX 233 #endif 234 235 /* FT_INCLUDE_ERR_PROTOS: Control whether function prototypes should be */ 236 /* included with */ 237 /* */ 238 /* #include <freetype/fterrors.h> */ 239 /* */ 240 /* This is only true where `FT_ERRORDEF` is */ 241 /* undefined. */ 242 /* */ 243 /* FT_ERR_PROTOS_DEFINED: Actual multiple-inclusion protection of */ 244 /* `fterrors.h`. */ 245 #ifdef FT_INCLUDE_ERR_PROTOS 246 #undef FT_INCLUDE_ERR_PROTOS 247 248 #ifndef FT_ERR_PROTOS_DEFINED 249 #define FT_ERR_PROTOS_DEFINED 250 251 252 FT_BEGIN_HEADER 253 254 /************************************************************************** 255 * 256 * @function: 257 * FT_Error_String 258 * 259 * @description: 260 * Retrieve the description of a valid FreeType error code. 261 * 262 * @input: 263 * error_code :: 264 * A valid FreeType error code. 265 * 266 * @return: 267 * A C~string or `NULL`, if any error occurred. 268 * 269 * @note: 270 * FreeType has to be compiled with `FT_CONFIG_OPTION_ERROR_STRINGS` or 271 * `FT_DEBUG_LEVEL_ERROR` to get meaningful descriptions. 272 * 'error_string' will be `NULL` otherwise. 273 * 274 * Module identification will be ignored: 275 * 276 * ```c 277 * strcmp( FT_Error_String( FT_Err_Unknown_File_Format ), 278 * FT_Error_String( BDF_Err_Unknown_File_Format ) ) == 0; 279 * ``` 280 */ 281 FT_EXPORT( const char* ) 282 FT_Error_String( FT_Error error_code ); 283 284 /* */ 285 286 FT_END_HEADER 287 288 289 #endif /* FT_ERR_PROTOS_DEFINED */ 290 291 #endif /* FT_INCLUDE_ERR_PROTOS */ 292 293 #endif /* !(FTERRORS_H_ && __FTERRORS_H__) */ 294 295 296 /* END */ 297
