FreeType » Docs » Miscellaneous » OpenType Validation
OpenType Validation¶
Synopsis¶
This section contains the declaration of functions to validate some OpenType tables (BASE, GDEF, GPOS, GSUB, JSTF, MATH).
FT_OpenType_Validate¶
Defined in FT_OPENTYPE_VALIDATE_H (freetype/ftotval.h).
  FT_EXPORT( FT_Error )
  FT_OpenType_Validate( FT_Face    face,
                        FT_UInt    validation_flags,
                        FT_Bytes  *BASE_table,
                        FT_Bytes  *GDEF_table,
                        FT_Bytes  *GPOS_table,
                        FT_Bytes  *GSUB_table,
                        FT_Bytes  *JSTF_table );
Validate various OpenType tables to assure that all offsets and indices are valid. The idea is that a higher-level library that actually does the text layout can access those tables without error checking (which can be quite time consuming).
input
| face | A handle to the input face. | 
| validation_flags | A bit field that specifies the tables to be validated. See  | 
output
| BASE_table | A pointer to the BASE table. | 
| GDEF_table | A pointer to the GDEF table. | 
| GPOS_table | A pointer to the GPOS table. | 
| GSUB_table | A pointer to the GSUB table. | 
| JSTF_table | A pointer to the JSTF table. | 
return
FreeType error code. 0 means success.
note
This function only works with OpenType fonts, returning an error otherwise.
After use, the application should deallocate the five tables with FT_OpenType_Free. A NULL value indicates that the table either doesn't exist in the font, or the application hasn't asked for validation.
FT_OpenType_Free¶
Defined in FT_OPENTYPE_VALIDATE_H (freetype/ftotval.h).
Free the buffer allocated by OpenType validator.
input
| face | A handle to the input face. | 
| table | The pointer to the buffer that is allocated by  | 
note
This function must be used to free the buffer allocated by FT_OpenType_Validate only.
FT_VALIDATE_OTXXX¶
Defined in FT_OPENTYPE_VALIDATE_H (freetype/ftotval.h).
#define FT_VALIDATE_BASE  0x0100
#define FT_VALIDATE_GDEF  0x0200
#define FT_VALIDATE_GPOS  0x0400
#define FT_VALIDATE_GSUB  0x0800
#define FT_VALIDATE_JSTF  0x1000
#define FT_VALIDATE_MATH  0x2000
#define FT_VALIDATE_OT  ( FT_VALIDATE_BASE | \
                          FT_VALIDATE_GDEF | \
                          FT_VALIDATE_GPOS | \
                          FT_VALIDATE_GSUB | \
                          FT_VALIDATE_JSTF | \
                          FT_VALIDATE_MATH )
A list of bit-field constants used with FT_OpenType_Validate to indicate which OpenType tables should be validated.
values
| FT_VALIDATE_BASE | Validate BASE table. | 
| FT_VALIDATE_GDEF | Validate GDEF table. | 
| FT_VALIDATE_GPOS | Validate GPOS table. | 
| FT_VALIDATE_GSUB | Validate GSUB table. | 
| FT_VALIDATE_JSTF | Validate JSTF table. | 
| FT_VALIDATE_MATH | Validate MATH table. | 
| FT_VALIDATE_OT | Validate all OpenType tables (BASE, GDEF, GPOS, GSUB, JSTF, MATH). |