FreeType-2.1.10 API Reference

OpenType Validation

Synopsis

This section contains the declaration of functions to validate some OpenType tables (BASE, GDEF, GPOS, GSUB, JSTF).

FT_VALIDATE_XXX


#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_OT  FT_VALIDATE_BASE | \
                        FT_VALIDATE_GDEF | \
                        FT_VALIDATE_GPOS | \
                        FT_VALIDATE_GSUB | \
                        FT_VALIDATE_JSTF

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_OT	Validate all OpenType tables (BASE, GDEF, GPOS, GSUB, JSTF).

FT_OpenType_Validate


  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 which 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 which specifies the tables to be validated. See FT_VALIDATE_XXX for possible values.

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 `free'. A NULL value indicates that the table either doesn't exist in the font, or the application hasn't asked for validation.