harfbuzz/src/hb-aat-feat-table.hh

/*
 * Copyright © 2018  Ebrahim Byagowi
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#ifndef HB_AAT_FEAT_TABLE_HH
#define HB_AAT_FEAT_TABLE_HH

#include "hb-aat-layout-common-private.hh"

#define HB_AAT_TAG_feat HB_TAG('f','e','a','t')


namespace AAT {

struct FeatureName {

  inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
  {
    TRACE_SANITIZE (this);
    return_trace (c->check_struct (this) &&
      (base+settingTable).sanitize (c, nSettings, base));
  }

  enum {
    Exclusive = 0x8000,		/* If set, the feature settings are mutually exclusive. */
    NotDefault = 0x4000,	/* If clear, then the setting with an index of 0 in
				 * the setting name array for this feature should
				 * be taken as the default for the feature
				 * (if one is required). If set, then bits 0-15 of this
				 * featureFlags field contain the index of the setting
				 * which is to be taken as the default. */
    IndexMask = 0x00FF		/* If bits 30 and 31 are set, then these sixteen bits
				 * indicate the index of the setting in the setting name
				 * array for this feature which should be taken
				 * as the default. */
  };

  struct SettingName
  {
    inline bool sanitize (hb_sanitize_context_t *c, const void *base HB_UNUSED) const
    {
      TRACE_SANITIZE (this);
      return_trace (c->check_struct (this) &&
	nameIndex > 255 && nameIndex < 32768);
    }

    protected:
    HBUINT16	setting;	/* The setting. */
    NameID	nameIndex;	/* The name table index for the setting's name.
				 * The nameIndex must be greater than 255 and less than 32768. */
    public:
    DEFINE_SIZE_STATIC (4);
  };

  protected:
  HBUINT16	feature;	/* Feature type. */
  HBUINT16	nSettings;	/* The number of records in the setting name array. */
  LOffsetTo<UnsizedArrayOf<SettingName> >
	settingTable;		/* Offset in bytes from the beginning of this table to
				 * this feature's setting name array. The actual type of
				 * record this offset refers to will depend on the
				 * exclusivity value, as described below. */
  HBUINT16	featureFlags;	/* Single-bit flags associated with the feature type. */
  HBINT16	nameIndex;	/* The name table index for the feature's name.
				 * This index has values greater than 255 and
				 * less than 32768. */
  public:
  DEFINE_SIZE_STATIC (12);
};

/*
 * feat -- Feature name
 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6fmtx.html
 */

struct feat
{
  static const hb_tag_t tableTag = HB_AAT_TAG_feat;

  inline bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (c->check_struct (this) &&
      names.sanitize (c, featureNameCount, this));
  }

  protected:
  FixedVersion<>version;	/* Version number of the feature name table
				 * (0x00010000 for the current version). */
  HBUINT16	featureNameCount;
				/* The number of entries in the feature name array. */
  HBUINT16	reserved1;	/* Reserved (set to zero). */
  HBUINT32	reserved2;	/* Reserved (set to zero). */
  UnsizedArrayOf<FeatureName>
		names;		/* The feature name array. */
  public:
  DEFINE_SIZE_STATIC (24);
};

} /* namespace AAT */

#endif /* HB_AAT_FEAT_TABLE_HH */