freetype2/include/freetype/ftotval.h

/****************************************************************************
 *
 * ftotval.h
 *
 *   FreeType API for validating OpenType tables (specification).
 *
 * Copyright (C) 2004-2021 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */


/****************************************************************************
 *
 *
 * Warning: This module might be moved to a different library in the
 *          future to avoid a tight dependency between FreeType and the
 *          OpenType specification.
 *
 *
 */


#ifndef FTOTVAL_H_
#define FTOTVAL_H_

#include <freetype/freetype.h>

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


FT_BEGIN_HEADER


  /**************************************************************************
   *
   * @section:
   *   ot_validation
   *
   * @title:
   *   OpenType Validation
   *
   * @abstract:
   *   An API to validate OpenType tables.
   *
   * @description:
   *   This section contains the declaration of functions to validate some
   *   OpenType tables (BASE, GDEF, GPOS, GSUB, JSTF, MATH).
   *
   * @order:
   *   FT_OpenType_Validate
   *   FT_OpenType_Free
   *
   *   FT_VALIDATE_OTXXX
   *
   */


  /**************************************************************************
   *
   * @enum:
   *    FT_VALIDATE_OTXXX
   *
   * @description:
   *    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).
   *
   */
#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 )


  /**************************************************************************
   *
   * @function:
   *    FT_OpenType_Validate
   *
   * @description:
   *    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
   *      @FT_VALIDATE_OTXXX 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
   *   @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_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 );


  /**************************************************************************
   *
   * @function:
   *    FT_OpenType_Free
   *
   * @description:
   *    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
   *      @FT_OpenType_Validate.
   *
   * @note:
   *   This function must be used to free the buffer allocated by
   *   @FT_OpenType_Validate only.
   */
  FT_EXPORT( void )
  FT_OpenType_Free( FT_Face   face,
                    FT_Bytes  table );


  /* */


FT_END_HEADER

#endif /* FTOTVAL_H_ */


/* END */