forked from minhngoc25a/freetype2
Doc fix.
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Werner Lemberg
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934a6159ba
commit
19be8620ec
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@ -19,82 +19,90 @@
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/**************************************************************************
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*
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* @section:
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* error_enumerations
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* error_enumerations
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*
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* @title:
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* Error Enumerations
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* Error Enumerations
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*
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* @abstract:
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* How to handle errors and error strings.
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* How to handle errors and error strings.
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*
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* @description:
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* The header file `fterrors.h` (which is automatically included by
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* `freetype.h` defines the handling of FreeType's enumeration constants.
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* It can also be used to generate error message strings with a small
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* macro trick explained below.
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* The header file `fterrors.h` (which is automatically included by
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* `freetype.h` defines the handling of FreeType's enumeration
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* constants. It can also be used to generate error message strings
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* with a small macro trick explained below.
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*
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* **Error Formats**
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* **Error Formats**
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*
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* The configuration macro FT_CONFIG_OPTION_USE_MODULE_ERRORS can be
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* defined in `ftoption.h` in order to make the higher byte indicate the
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* module where the error has happened (this is not compatible with
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* standard builds of FreeType~2, however). See the file `ftmoderr.h` for
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* more details.
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* The configuration macro FT_CONFIG_OPTION_USE_MODULE_ERRORS can be
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* defined in `ftoption.h` in order to make the higher byte indicate the
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* module where the error has happened (this is not compatible with
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* standard builds of FreeType~2, however). See the file `ftmoderr.h`
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* for more details.
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*
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* **Error Message Strings**
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* **Error Message Strings**
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*
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* Error definitions are set up with special macros that allow client
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* applications to build a table of error message strings. The strings
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* are not included in a normal build of FreeType~2 to save space (most
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* client applications do not use them).
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* Error definitions are set up with special macros that allow client
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* applications to build a table of error message strings. The strings
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* are not included in a normal build of FreeType~2 to save space (most
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* client applications do not use them).
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*
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* To do so, you have to define the following macros before including this
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* file.
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* To do so, you have to define the following macros before including
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* this file.
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*
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* ```
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* FT_ERROR_START_LIST
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* ```
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* ```
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* FT_ERROR_START_LIST
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* ```
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*
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* This macro is called before anything else to define the start of the
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* error list. It is followed by several FT_ERROR_DEF calls.
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* This macro is called before anything else to define the start of the
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* error list. It is followed by several FT_ERROR_DEF calls.
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*
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* ```
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* FT_ERROR_DEF( e, v, s )
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* ```
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* ```
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* FT_ERROR_DEF( e, v, s )
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* ```
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*
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* This macro is called to define one single error. 'e' is the error code
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* identifier (e.g., `Invalid_Argument`), 'v' is the error's numerical
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* value, and 's' is the corresponding error string.
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* This macro is called to define one single error. 'e' is the error
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* code identifier (e.g., `Invalid_Argument`), 'v' is the error's
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* numerical value, and 's' is the corresponding error string.
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*
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* ```
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* FT_ERROR_END_LIST
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* ```
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* ```
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* FT_ERROR_END_LIST
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* ```
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*
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* This macro ends the list.
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* This macro ends the list.
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*
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* Additionally, you have to undefine `FTERRORS_H_` before #including this
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* file.
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* Additionally, you have to undefine `FTERRORS_H_` before #including
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* this file.
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*
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* Here is a simple example.
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* Here is a simple example.
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*
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* ```
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* #undef FTERRORS_H_
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* #define FT_ERRORDEF( e, v, s ) { e, s },
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* #define FT_ERROR_START_LIST {
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* #define FT_ERROR_END_LIST { 0, NULL } };
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* ```
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* #undef FTERRORS_H_
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* #define FT_ERRORDEF( e, v, s ) { e, s },
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* #define FT_ERROR_START_LIST {
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* #define FT_ERROR_END_LIST { 0, NULL } };
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*
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* const struct
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* {
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* int err_code;
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* const char* err_msg;
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* } ft_errors[] =
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* const struct
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* {
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* int err_code;
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* const char* err_msg;
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* } ft_errors[] =
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*
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* #include FT_ERRORS_H
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* ```
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* #include FT_ERRORS_H
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* ```
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*
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* Note that `FT_Err_Ok` is _not_ defined with `FT_ERRORDEF`; it is
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* always zero.
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* An alternative to using an array is a switch statement.
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*
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* ```
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* #undef FTERRORS_H_
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* #define FT_ERROR_START_LIST switch ( error_code ) {
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* #define FT_ERRORDEF( e, v, s ) case v: return s;
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* #define FT_ERROR_END_LIST }
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* ```
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*
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* If you use FT_CONFIG_OPTION_USE_MODULE_ERRORS, 'error_code' should be
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* replaced with 'FT_ERROR_BASE(error_code)' in the last example.
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*/
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/* */
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@ -37,6 +37,7 @@
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* provides some macros in `fttypes.h`.
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*
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* FT_ERR( err )
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*
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* Add current error module prefix (as defined with the `FT_ERR_PREFIX`
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* macro) to 'err'. For example, in the BDF module the line
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*
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@ -49,7 +50,9 @@
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* For simplicity, you can always use `FT_Err_Ok` directly instead of
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* 'FT_ERR( Ok )'.
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*
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* FT_ERR_EQ( errcode, err ) FT_ERR_NEQ( errcode, err )
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* FT_ERR_EQ( errcode, err )
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* FT_ERR_NEQ( errcode, err )
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*
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* Compare error code 'errcode' with the error 'err' for equality and
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* inequality, respectively. Example:
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*
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@ -63,9 +66,10 @@
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* if ( error == FT_Err_Invalid_Outline )
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* ...
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*
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* FT_ERROR_BASE( errcode ) FT_ERROR_MODULE( errcode )
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* Get base error and module error code, respectively.
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* FT_ERROR_BASE( errcode )
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* FT_ERROR_MODULE( errcode )
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*
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* Get base error and module error code, respectively.
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*
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* It can also be used to create a module error message table easily with
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* something like
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