kc3-lang/harfbuzz/src/hb-buffer.h

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  Date : 2025-03-24T00:33:53
  

  11.0.0
  

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• src/hb-buffer.h

• /*
   * Copyright © 1998-2004  David Turner and Werner Lemberg
   * Copyright © 2004,2007,2009  Red Hat, Inc.
   * Copyright © 2011,2012  Google, Inc.
   *
   *  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.
   *
   * Red Hat Author(s): Owen Taylor, Behdad Esfahbod
   * Google Author(s): Behdad Esfahbod
   */
  
  #if !defined(HB_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
  #error "Include <hb.h> instead."
  #endif
  
  #ifndef HB_BUFFER_H
  #define HB_BUFFER_H
  
  #include "hb-common.h"
  #include "hb-unicode.h"
  #include "hb-font.h"
  
  HB_BEGIN_DECLS
  
  /**
   * hb_glyph_info_t:
   * @codepoint: either a Unicode code point (before shaping) or a glyph index
   *             (after shaping).
   * @cluster: the index of the character in the original text that corresponds
   *           to this #hb_glyph_info_t, or whatever the client passes to
   *           hb_buffer_add(). More than one #hb_glyph_info_t can have the same
   *           @cluster value, if they resulted from the same character (e.g. one
   *           to many glyph substitution), and when more than one character gets
   *           merged in the same glyph (e.g. many to one glyph substitution) the
   *           #hb_glyph_info_t will have the smallest cluster value of them.
   *           By default some characters are merged into the same cluster
   *           (e.g. combining marks have the same cluster as their bases)
   *           even if they are separate glyphs, hb_buffer_set_cluster_level()
   *           allow selecting more fine-grained cluster handling.
   *
   * The #hb_glyph_info_t is the structure that holds information about the
   * glyphs and their relation to input text.
   */
  typedef struct hb_glyph_info_t {
    hb_codepoint_t codepoint;
    /*< private >*/
    hb_mask_t      mask;
    /*< public >*/
    uint32_t       cluster;
  
    /*< private >*/
    hb_var_int_t   var1;
    hb_var_int_t   var2;
  } hb_glyph_info_t;
  
  /**
   * hb_glyph_flags_t:
   * @HB_GLYPH_FLAG_UNSAFE_TO_BREAK: Indicates that if input text is broken at the
   * 				   beginning of the cluster this glyph is part of,
   * 				   then both sides need to be re-shaped, as the
   * 				   result might be different.
   * 				   On the flip side, it means that when this
   * 				   flag is not present, then it is safe to break
   * 				   the glyph-run at the beginning of this
   * 				   cluster, and the two sides will represent the
   * 				   exact same result one would get if breaking
   * 				   input text at the beginning of this cluster
   * 				   and shaping the two sides separately.
   * 				   This can be used to optimize paragraph
   * 				   layout, by avoiding re-shaping of each line
   * 				   after line-breaking.
   * @HB_GLYPH_FLAG_UNSAFE_TO_CONCAT: Indicates that if input text is changed on one
   * 				   side of the beginning of the cluster this glyph
   * 				   is part of, then the shaping results for the
   * 				   other side might change.
   * 				   Note that the absence of this flag will NOT by
   * 				   itself mean that it IS safe to concat text.
   * 				   Only two pieces of text both of which clear of
   * 				   this flag can be concatenated safely.
   * 				   This can be used to optimize paragraph
   * 				   layout, by avoiding re-shaping of each line
   * 				   after line-breaking, by limiting the
   * 				   reshaping to a small piece around the
   * 				   breaking position only, even if the breaking
   * 				   position carries the
   * 				   #HB_GLYPH_FLAG_UNSAFE_TO_BREAK or when
   * 				   hyphenation or other text transformation
   * 				   happens at line-break position, in the following
   * 				   way:
   * 				   1. Iterate back from the line-break position
   * 				   until the first cluster start position that is
   * 				   NOT unsafe-to-concat, 2. shape the segment from
   * 				   there till the end of line, 3. check whether the
   * 				   resulting glyph-run also is clear of the
   * 				   unsafe-to-concat at its start-of-text position;
   * 				   if it is, just splice it into place and the line
   * 				   is shaped; If not, move on to a position further
   * 				   back that is clear of unsafe-to-concat and retry
   * 				   from there, and repeat.
   * 				   At the start of next line a similar algorithm can
   * 				   be implemented. That is: 1. Iterate forward from
   * 				   the line-break position until the first cluster
   * 				   start position that is NOT unsafe-to-concat, 2.
   * 				   shape the segment from beginning of the line to
   * 				   that position, 3. check whether the resulting
   * 				   glyph-run also is clear of the unsafe-to-concat
   * 				   at its end-of-text position; if it is, just splice
   * 				   it into place and the beginning is shaped; If not,
   * 				   move on to a position further forward that is clear
   * 				   of unsafe-to-concat and retry up to there, and repeat.
   * 				   A slight complication will arise in the
   * 				   implementation of the algorithm above,
   * 				   because while our buffer API has a way to
   * 				   return flags for position corresponding to
   * 				   start-of-text, there is currently no position
   * 				   corresponding to end-of-text.  This limitation
   * 				   can be alleviated by shaping more text than needed
   * 				   and looking for unsafe-to-concat flag within text
   * 				   clusters.
   * 				   The #HB_GLYPH_FLAG_UNSAFE_TO_BREAK flag will
   * 				   always imply this flag.
   *				   To use this flag, you must enable the buffer flag
   *				   @HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT during
   *				   shaping, otherwise the buffer flag will not be
   *				   reliably produced.
   * 				   Since: 4.0.0
   * @HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL: In scripts that use elongation (Arabic,
  				   Mongolian, Syriac, etc.), this flag signifies
  				   that it is safe to insert a U+0640 TATWEEL
  				   character before this cluster for elongation.
  				   This flag does not determine the
  				   script-specific elongation places, but only
  				   when it is safe to do the elongation without
  				   interrupting text shaping.
  				   Since: 5.1.0
   * @HB_GLYPH_FLAG_DEFINED: All the currently defined flags.
   *
   * Flags for #hb_glyph_info_t.
   *
   * Since: 1.5.0
   */
  typedef enum { /*< flags >*/
    HB_GLYPH_FLAG_UNSAFE_TO_BREAK			= 0x00000001,
    HB_GLYPH_FLAG_UNSAFE_TO_CONCAT		= 0x00000002,
    HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL		= 0x00000004,
  
    HB_GLYPH_FLAG_DEFINED				= 0x00000007 /* OR of all defined flags */
  } hb_glyph_flags_t;
  
  HB_EXTERN hb_glyph_flags_t
  hb_glyph_info_get_glyph_flags (const hb_glyph_info_t *info);
  
  #define hb_glyph_info_get_glyph_flags(info) \
  	((hb_glyph_flags_t) ((unsigned int) (info)->mask & HB_GLYPH_FLAG_DEFINED))
  
  
  /**
   * hb_glyph_position_t:
   * @x_advance: how much the line advances after drawing this glyph when setting
   *             text in horizontal direction.
   * @y_advance: how much the line advances after drawing this glyph when setting
   *             text in vertical direction.
   * @x_offset: how much the glyph moves on the X-axis before drawing it, this
   *            should not affect how much the line advances.
   * @y_offset: how much the glyph moves on the Y-axis before drawing it, this
   *            should not affect how much the line advances.
   *
   * The #hb_glyph_position_t is the structure that holds the positions of the
   * glyph in both horizontal and vertical directions. All positions in
   * #hb_glyph_position_t are relative to the current point.
   *
   */
  typedef struct hb_glyph_position_t {
    hb_position_t  x_advance;
    hb_position_t  y_advance;
    hb_position_t  x_offset;
    hb_position_t  y_offset;
  
    /*< private >*/
    hb_var_int_t   var;
  } hb_glyph_position_t;
  
  /**
   * hb_segment_properties_t:
   * @direction: the #hb_direction_t of the buffer, see hb_buffer_set_direction().
   * @script: the #hb_script_t of the buffer, see hb_buffer_set_script().
   * @language: the #hb_language_t of the buffer, see hb_buffer_set_language().
   *
   * The structure that holds various text properties of an #hb_buffer_t. Can be
   * set and retrieved using hb_buffer_set_segment_properties() and
   * hb_buffer_get_segment_properties(), respectively.
   */
  typedef struct hb_segment_properties_t {
    hb_direction_t  direction;
    hb_script_t     script;
    hb_language_t   language;
    /*< private >*/
    void           *reserved1;
    void           *reserved2;
  } hb_segment_properties_t;
  
  /**
   * HB_SEGMENT_PROPERTIES_DEFAULT:
   *
   * The default #hb_segment_properties_t of of freshly created #hb_buffer_t.
   */
  #define HB_SEGMENT_PROPERTIES_DEFAULT {HB_DIRECTION_INVALID, \
  				       HB_SCRIPT_INVALID, \
  				       HB_LANGUAGE_INVALID, \
  				       (void *) 0, \
  				       (void *) 0}
  
  HB_EXTERN hb_bool_t
  hb_segment_properties_equal (const hb_segment_properties_t *a,
  			     const hb_segment_properties_t *b);
  
  HB_EXTERN unsigned int
  hb_segment_properties_hash (const hb_segment_properties_t *p);
  
  HB_EXTERN void
  hb_segment_properties_overlay (hb_segment_properties_t *p,
  			       const hb_segment_properties_t *src);
  
  
  /**
   * hb_buffer_t:
   *
   * The main structure holding the input text and its properties before shaping,
   * and output glyphs and their information after shaping.
   */
  
  typedef struct hb_buffer_t hb_buffer_t;
  
  HB_EXTERN hb_buffer_t *
  hb_buffer_create (void);
  
  HB_EXTERN hb_buffer_t *
  hb_buffer_create_similar (const hb_buffer_t *src);
  
  HB_EXTERN void
  hb_buffer_reset (hb_buffer_t *buffer);
  
  
  HB_EXTERN hb_buffer_t *
  hb_buffer_get_empty (void);
  
  HB_EXTERN hb_buffer_t *
  hb_buffer_reference (hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_destroy (hb_buffer_t *buffer);
  
  HB_EXTERN hb_bool_t
  hb_buffer_set_user_data (hb_buffer_t        *buffer,
  			 hb_user_data_key_t *key,
  			 void *              data,
  			 hb_destroy_func_t   destroy,
  			 hb_bool_t           replace);
  
  HB_EXTERN void *
  hb_buffer_get_user_data (const hb_buffer_t  *buffer,
  			 hb_user_data_key_t *key);
  
  
  /**
   * hb_buffer_content_type_t:
   * @HB_BUFFER_CONTENT_TYPE_INVALID: Initial value for new buffer.
   * @HB_BUFFER_CONTENT_TYPE_UNICODE: The buffer contains input characters (before shaping).
   * @HB_BUFFER_CONTENT_TYPE_GLYPHS: The buffer contains output glyphs (after shaping).
   *
   * The type of #hb_buffer_t contents.
   */
  typedef enum {
    HB_BUFFER_CONTENT_TYPE_INVALID = 0,
    HB_BUFFER_CONTENT_TYPE_UNICODE,
    HB_BUFFER_CONTENT_TYPE_GLYPHS
  } hb_buffer_content_type_t;
  
  HB_EXTERN void
  hb_buffer_set_content_type (hb_buffer_t              *buffer,
  			    hb_buffer_content_type_t  content_type);
  
  HB_EXTERN hb_buffer_content_type_t
  hb_buffer_get_content_type (const hb_buffer_t *buffer);
  
  
  HB_EXTERN void
  hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
  			     hb_unicode_funcs_t *unicode_funcs);
  
  HB_EXTERN hb_unicode_funcs_t *
  hb_buffer_get_unicode_funcs (const hb_buffer_t  *buffer);
  
  HB_EXTERN void
  hb_buffer_set_direction (hb_buffer_t    *buffer,
  			 hb_direction_t  direction);
  
  HB_EXTERN hb_direction_t
  hb_buffer_get_direction (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_script (hb_buffer_t *buffer,
  		      hb_script_t  script);
  
  HB_EXTERN hb_script_t
  hb_buffer_get_script (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_language (hb_buffer_t   *buffer,
  			hb_language_t  language);
  
  
  HB_EXTERN hb_language_t
  hb_buffer_get_language (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_segment_properties (hb_buffer_t *buffer,
  				  const hb_segment_properties_t *props);
  
  HB_EXTERN void
  hb_buffer_get_segment_properties (const hb_buffer_t *buffer,
  				  hb_segment_properties_t *props);
  
  HB_EXTERN void
  hb_buffer_guess_segment_properties (hb_buffer_t *buffer);
  
  
  /**
   * hb_buffer_flags_t:
   * @HB_BUFFER_FLAG_DEFAULT: the default buffer flag.
   * @HB_BUFFER_FLAG_BOT: flag indicating that special handling of the beginning
   *                      of text paragraph can be applied to this buffer. Should usually
   *                      be set, unless you are passing to the buffer only part
   *                      of the text without the full context.
   * @HB_BUFFER_FLAG_EOT: flag indicating that special handling of the end of text
   *                      paragraph can be applied to this buffer, similar to
   *                      @HB_BUFFER_FLAG_BOT.
   * @HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES:
   *                      flag indication that character with Default_Ignorable
   *                      Unicode property should use the corresponding glyph
   *                      from the font, instead of hiding them (done by
   *                      replacing them with the space glyph and zeroing the
   *                      advance width.)  This flag takes precedence over
   *                      @HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES.
   * @HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES:
   *                      flag indication that character with Default_Ignorable
   *                      Unicode property should be removed from glyph string
   *                      instead of hiding them (done by replacing them with the
   *                      space glyph and zeroing the advance width.)
   *                      @HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES takes
   *                      precedence over this flag. Since: 1.8.0
   * @HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE:
   *                      flag indicating that a dotted circle should
   *                      not be inserted in the rendering of incorrect
   *                      character sequences (such at <0905 093E>). Since: 2.4.0
   * @HB_BUFFER_FLAG_VERIFY:
   *                      flag indicating that the hb_shape() call and its variants
   *                      should perform various verification processes on the results
   *                      of the shaping operation on the buffer.  If the verification
   *                      fails, then either a buffer message is sent, if a message
   *                      handler is installed on the buffer, or a message is written
   *                      to standard error.  In either case, the shaping result might
   *                      be modified to show the failed output. Since: 3.4.0
   * @HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT:
   *                      flag indicating that the @HB_GLYPH_FLAG_UNSAFE_TO_CONCAT
   *                      glyph-flag should be produced by the shaper. By default
   *                      it will not be produced since it incurs a cost. Since: 4.0.0
   * @HB_BUFFER_FLAG_PRODUCE_SAFE_TO_INSERT_TATWEEL:
   *                      flag indicating that the @HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL
   *                      glyph-flag should be produced by the shaper. By default
   *                      it will not be produced. Since: 5.1.0
   * @HB_BUFFER_FLAG_DEFINED: All currently defined flags: Since: 4.4.0
   *
   * Flags for #hb_buffer_t.
   *
   * Since: 0.9.20
   */
  typedef enum { /*< flags >*/
    HB_BUFFER_FLAG_DEFAULT			= 0x00000000u,
    HB_BUFFER_FLAG_BOT				= 0x00000001u, /* Beginning-of-text */
    HB_BUFFER_FLAG_EOT				= 0x00000002u, /* End-of-text */
    HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES	= 0x00000004u,
    HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES	= 0x00000008u,
    HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE	= 0x00000010u,
    HB_BUFFER_FLAG_VERIFY				= 0x00000020u,
    HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT	= 0x00000040u,
    HB_BUFFER_FLAG_PRODUCE_SAFE_TO_INSERT_TATWEEL	= 0x00000080u,
  
    HB_BUFFER_FLAG_DEFINED			= 0x000000FFu
  } hb_buffer_flags_t;
  
  HB_EXTERN void
  hb_buffer_set_flags (hb_buffer_t       *buffer,
  		     hb_buffer_flags_t  flags);
  
  HB_EXTERN hb_buffer_flags_t
  hb_buffer_get_flags (const hb_buffer_t *buffer);
  
  /**
   * hb_buffer_cluster_level_t:
   * @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES: Return cluster values grouped by graphemes into
   *   monotone order.
   * @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS: Return cluster values grouped into monotone order.
   * @HB_BUFFER_CLUSTER_LEVEL_CHARACTERS: Don't group cluster values.
   * @HB_BUFFER_CLUSTER_LEVEL_DEFAULT: Default cluster level,
   *   equal to @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES.
   * @HB_BUFFER_CLUSTER_LEVEL_GRAPHEMES: Only group clusters, but don't enforce monotone order.
   *
   * Data type for holding HarfBuzz's clustering behavior options. The cluster level
   * dictates one aspect of how HarfBuzz will treat non-base characters
   * during shaping.
   *
   * In @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES, non-base
   * characters are merged into the cluster of the base character that precedes them.
   * There is also cluster merging every time the clusters will otherwise become non-monotone.
   *
   * In @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS, non-base characters are initially
   * assigned their own cluster values, which are not merged into preceding base
   * clusters. This allows HarfBuzz to perform additional operations like reorder
   * sequences of adjacent marks. The output is still monotone, but the cluster
   * values are more granular.
   *
   * In @HB_BUFFER_CLUSTER_LEVEL_CHARACTERS, non-base characters are assigned their
   * own cluster values, which are not merged into preceding base clusters. Moreover,
   * the cluster values are not merged into monotone order. This is the most granular
   * cluster level, and it is useful for clients that need to know the exact cluster
   * values of each character, but is harder to use for clients, since clusters
   * might appear in any order.
   *
   * In @HB_BUFFER_CLUSTER_LEVEL_GRAPHEMES, non-base characters are merged into the
   * cluster of the base character that precedes them. This is similar to the Unicode
   * Grapheme Cluster algorithm, but it is not exactly the same. The output is
   * not forced to be monotone. This is useful for clients that want to use HarfBuzz
   * as a cheap implementation of the Unicode Grapheme Cluster algorithm.
   *
   * @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES is the default, because it maintains
   * backward compatibility with older versions of HarfBuzz. New client programs that
   * do not need to maintain such backward compatibility are recommended to use
   * @HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS instead of the default.
   *
   * Since: 0.9.42
   */
  typedef enum {
    HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES	= 0,
    HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS	= 1,
    HB_BUFFER_CLUSTER_LEVEL_CHARACTERS		= 2,
    HB_BUFFER_CLUSTER_LEVEL_GRAPHEMES		= 3,
    HB_BUFFER_CLUSTER_LEVEL_DEFAULT = HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES
  } hb_buffer_cluster_level_t;
  
  /**
   * HB_BUFFER_CLUSTER_LEVEL_IS_MONOTONE:
   * @level: #hb_buffer_cluster_level_t to test
   *
   * Tests whether a cluster level groups cluster values into monotone order.
   * Requires that the level be valid.
   *
   * Since: 11.0.0
   */
  #define HB_BUFFER_CLUSTER_LEVEL_IS_MONOTONE(level) \
  	((bool) ((1u << (unsigned) (level)) & \
  		 ((1u << HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES) | \
  		  (1u << HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS))))
  
  /**
   * HB_BUFFER_CLUSTER_LEVEL_IS_GRAPHEMES:
   * @level: #hb_buffer_cluster_level_t to test
   *
   * Tests whether a cluster level groups cluster values by graphemes. Requires
   * that the level be valid.
   *
   * Since: 11.0.0
   */
  #define HB_BUFFER_CLUSTER_LEVEL_IS_GRAPHEMES(level) \
  	((bool) ((1u << (unsigned) (level)) & \
  		 ((1u << HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES) | \
  		  (1u << HB_BUFFER_CLUSTER_LEVEL_GRAPHEMES))))
  
  /**
   * HB_BUFFER_CLUSTER_LEVEL_IS_CHARACTERS
   * @level: #hb_buffer_cluster_level_t to test
   *
   * Tests whether a cluster level does not group cluster values by graphemes.
   * Requires that the level be valid.
   *
   * Since: 11.0.0
   */
  #define HB_BUFFER_CLUSTER_LEVEL_IS_CHARACTERS(level) \
  	((bool) ((1u << (unsigned) (level)) & \
  		 ((1u << HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARCATERS) | \
  		  (1u << HB_BUFFER_CLUSTER_LEVEL_CHARACTERS))))
  
  HB_EXTERN void
  hb_buffer_set_cluster_level (hb_buffer_t               *buffer,
  			     hb_buffer_cluster_level_t  cluster_level);
  
  HB_EXTERN hb_buffer_cluster_level_t
  hb_buffer_get_cluster_level (const hb_buffer_t *buffer);
  
  /**
   * HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT:
   *
   * The default code point for replacing invalid characters in a given encoding.
   * Set to U+FFFD REPLACEMENT CHARACTER.
   *
   * Since: 0.9.31
   */
  #define HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT 0xFFFDu
  
  HB_EXTERN void
  hb_buffer_set_replacement_codepoint (hb_buffer_t    *buffer,
  				     hb_codepoint_t  replacement);
  
  HB_EXTERN hb_codepoint_t
  hb_buffer_get_replacement_codepoint (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_invisible_glyph (hb_buffer_t    *buffer,
  			       hb_codepoint_t  invisible);
  
  HB_EXTERN hb_codepoint_t
  hb_buffer_get_invisible_glyph (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_not_found_glyph (hb_buffer_t    *buffer,
  			       hb_codepoint_t  not_found);
  
  HB_EXTERN hb_codepoint_t
  hb_buffer_get_not_found_glyph (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_not_found_variation_selector_glyph (hb_buffer_t    *buffer,
  						  hb_codepoint_t  not_found_variation_selector);
  
  HB_EXTERN hb_codepoint_t
  hb_buffer_get_not_found_variation_selector_glyph (const hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_set_random_state (hb_buffer_t    *buffer,
  			    unsigned        state);
  
  HB_EXTERN unsigned
  hb_buffer_get_random_state (const hb_buffer_t *buffer);
  
  /*
   * Content API.
   */
  
  HB_EXTERN void
  hb_buffer_clear_contents (hb_buffer_t *buffer);
  
  HB_EXTERN hb_bool_t
  hb_buffer_pre_allocate (hb_buffer_t  *buffer,
  			unsigned int  size);
  
  
  HB_EXTERN hb_bool_t
  hb_buffer_allocation_successful (hb_buffer_t  *buffer);
  
  HB_EXTERN void
  hb_buffer_reverse (hb_buffer_t *buffer);
  
  HB_EXTERN void
  hb_buffer_reverse_range (hb_buffer_t *buffer,
  			 unsigned int start, unsigned int end);
  
  HB_EXTERN void
  hb_buffer_reverse_clusters (hb_buffer_t *buffer);
  
  
  /* Filling the buffer in */
  
  HB_EXTERN void
  hb_buffer_add (hb_buffer_t    *buffer,
  	       hb_codepoint_t  codepoint,
  	       unsigned int    cluster);
  
  HB_EXTERN void
  hb_buffer_add_utf8 (hb_buffer_t  *buffer,
  		    const char   *text,
  		    int           text_length,
  		    unsigned int  item_offset,
  		    int           item_length);
  
  HB_EXTERN void
  hb_buffer_add_utf16 (hb_buffer_t    *buffer,
  		     const uint16_t *text,
  		     int             text_length,
  		     unsigned int    item_offset,
  		     int             item_length);
  
  HB_EXTERN void
  hb_buffer_add_utf32 (hb_buffer_t    *buffer,
  		     const uint32_t *text,
  		     int             text_length,
  		     unsigned int    item_offset,
  		     int             item_length);
  
  HB_EXTERN void
  hb_buffer_add_latin1 (hb_buffer_t   *buffer,
  		      const uint8_t *text,
  		      int            text_length,
  		      unsigned int   item_offset,
  		      int            item_length);
  
  HB_EXTERN void
  hb_buffer_add_codepoints (hb_buffer_t          *buffer,
  			  const hb_codepoint_t *text,
  			  int                   text_length,
  			  unsigned int          item_offset,
  			  int                   item_length);
  
  HB_EXTERN void
  hb_buffer_append (hb_buffer_t *buffer,
  		  const hb_buffer_t *source,
  		  unsigned int start,
  		  unsigned int end);
  
  HB_EXTERN hb_bool_t
  hb_buffer_set_length (hb_buffer_t  *buffer,
  		      unsigned int  length);
  
  HB_EXTERN unsigned int
  hb_buffer_get_length (const hb_buffer_t *buffer);
  
  /* Getting glyphs out of the buffer */
  
  HB_EXTERN hb_glyph_info_t *
  hb_buffer_get_glyph_infos (hb_buffer_t  *buffer,
  			   unsigned int *length);
  
  HB_EXTERN hb_glyph_position_t *
  hb_buffer_get_glyph_positions (hb_buffer_t  *buffer,
  			       unsigned int *length);
  
  HB_EXTERN hb_bool_t
  hb_buffer_has_positions (hb_buffer_t  *buffer);
  
  
  HB_EXTERN void
  hb_buffer_normalize_glyphs (hb_buffer_t *buffer);
  
  
  /*
   * Serialize
   */
  
  /**
   * hb_buffer_serialize_flags_t:
   * @HB_BUFFER_SERIALIZE_FLAG_DEFAULT: serialize glyph names, clusters and positions.
   * @HB_BUFFER_SERIALIZE_FLAG_NO_CLUSTERS: do not serialize glyph cluster.
   * @HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS: do not serialize glyph position information.
   * @HB_BUFFER_SERIALIZE_FLAG_NO_GLYPH_NAMES: do no serialize glyph name.
   * @HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS: serialize glyph extents.
   * @HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS: serialize glyph flags. Since: 1.5.0
   * @HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES: do not serialize glyph advances,
   *  glyph offsets will reflect absolute glyph positions. Since: 1.8.0
   * @HB_BUFFER_SERIALIZE_FLAG_DEFINED: All currently defined flags. Since: 4.4.0
   *
   * Flags that control what glyph information are serialized in hb_buffer_serialize_glyphs().
   *
   * Since: 0.9.20
   */
  typedef enum { /*< flags >*/
    HB_BUFFER_SERIALIZE_FLAG_DEFAULT		= 0x00000000u,
    HB_BUFFER_SERIALIZE_FLAG_NO_CLUSTERS		= 0x00000001u,
    HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS		= 0x00000002u,
    HB_BUFFER_SERIALIZE_FLAG_NO_GLYPH_NAMES	= 0x00000004u,
    HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS	= 0x00000008u,
    HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS		= 0x00000010u,
    HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES		= 0x00000020u,
  
    HB_BUFFER_SERIALIZE_FLAG_DEFINED		= 0x0000003Fu
  } hb_buffer_serialize_flags_t;
  
  /**
   * hb_buffer_serialize_format_t:
   * @HB_BUFFER_SERIALIZE_FORMAT_TEXT: a human-readable, plain text format.
   * @HB_BUFFER_SERIALIZE_FORMAT_JSON: a machine-readable JSON format.
   * @HB_BUFFER_SERIALIZE_FORMAT_INVALID: invalid format.
   *
   * The buffer serialization and de-serialization format used in
   * hb_buffer_serialize_glyphs() and hb_buffer_deserialize_glyphs().
   *
   * Since: 0.9.2
   */
  typedef enum {
    HB_BUFFER_SERIALIZE_FORMAT_TEXT	= HB_TAG('T','E','X','T'),
    HB_BUFFER_SERIALIZE_FORMAT_JSON	= HB_TAG('J','S','O','N'),
    HB_BUFFER_SERIALIZE_FORMAT_INVALID	= HB_TAG_NONE
  } hb_buffer_serialize_format_t;
  
  HB_EXTERN hb_buffer_serialize_format_t
  hb_buffer_serialize_format_from_string (const char *str, int len);
  
  HB_EXTERN const char *
  hb_buffer_serialize_format_to_string (hb_buffer_serialize_format_t format);
  
  HB_EXTERN const char **
  hb_buffer_serialize_list_formats (void);
  
  HB_EXTERN unsigned int
  hb_buffer_serialize_glyphs (hb_buffer_t *buffer,
  			    unsigned int start,
  			    unsigned int end,
  			    char *buf,
  			    unsigned int buf_size,
  			    unsigned int *buf_consumed,
  			    hb_font_t *font,
  			    hb_buffer_serialize_format_t format,
  			    hb_buffer_serialize_flags_t flags);
  
  HB_EXTERN unsigned int
  hb_buffer_serialize_unicode (hb_buffer_t *buffer,
  			     unsigned int start,
  			     unsigned int end,
  			     char *buf,
  			     unsigned int buf_size,
  			     unsigned int *buf_consumed,
  			     hb_buffer_serialize_format_t format,
  			     hb_buffer_serialize_flags_t flags);
  
  HB_EXTERN unsigned int
  hb_buffer_serialize (hb_buffer_t *buffer,
  		     unsigned int start,
  		     unsigned int end,
  		     char *buf,
  		     unsigned int buf_size,
  		     unsigned int *buf_consumed,
  		     hb_font_t *font,
  		     hb_buffer_serialize_format_t format,
  		     hb_buffer_serialize_flags_t flags);
  
  HB_EXTERN hb_bool_t
  hb_buffer_deserialize_glyphs (hb_buffer_t *buffer,
  			      const char *buf,
  			      int buf_len,
  			      const char **end_ptr,
  			      hb_font_t *font,
  			      hb_buffer_serialize_format_t format);
  
  HB_EXTERN hb_bool_t
  hb_buffer_deserialize_unicode (hb_buffer_t *buffer,
  			       const char *buf,
  			       int buf_len,
  			       const char **end_ptr,
  			       hb_buffer_serialize_format_t format);
  
  
  
  /*
   * Compare buffers
   */
  
  /**
   * hb_buffer_diff_flags_t:
   * @HB_BUFFER_DIFF_FLAG_EQUAL: equal buffers.
   * @HB_BUFFER_DIFF_FLAG_CONTENT_TYPE_MISMATCH: buffers with different
   *     #hb_buffer_content_type_t.
   * @HB_BUFFER_DIFF_FLAG_LENGTH_MISMATCH: buffers with differing length.
   * @HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT: `.notdef` glyph is present in the
   *     reference buffer.
   * @HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT: dotted circle glyph is present
   *     in the reference buffer.
   * @HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH: difference in #hb_glyph_info_t.codepoint
   * @HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH: difference in #hb_glyph_info_t.cluster
   * @HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH: difference in #hb_glyph_flags_t.
   * @HB_BUFFER_DIFF_FLAG_POSITION_MISMATCH: difference in #hb_glyph_position_t.
   *
   * Flags from comparing two #hb_buffer_t's.
   *
   * Buffer with different #hb_buffer_content_type_t cannot be meaningfully
   * compared in any further detail.
   *
   * For buffers with differing length, the per-glyph comparison is not
   * attempted, though we do still scan reference buffer for dotted circle and
   * `.notdef` glyphs.
   *
   * If the buffers have the same length, we compare them glyph-by-glyph and
   * report which aspect(s) of the glyph info/position are different.
   *
   * Since: 1.5.0
   */
  typedef enum { /*< flags >*/
    HB_BUFFER_DIFF_FLAG_EQUAL			= 0x0000,
  
    /* Buffers with different content_type cannot be meaningfully compared
     * in any further detail. */
    HB_BUFFER_DIFF_FLAG_CONTENT_TYPE_MISMATCH	= 0x0001,
  
    /* For buffers with differing length, the per-glyph comparison is not
     * attempted, though we do still scan reference for dottedcircle / .notdef
     * glyphs. */
    HB_BUFFER_DIFF_FLAG_LENGTH_MISMATCH		= 0x0002,
  
    /* We want to know if dottedcircle / .notdef glyphs are present in the
     * reference, as we may not care so much about other differences in this
     * case. */
    HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT		= 0x0004,
    HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT	= 0x0008,
  
    /* If the buffers have the same length, we compare them glyph-by-glyph
     * and report which aspect(s) of the glyph info/position are different. */
    HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH	= 0x0010,
    HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH		= 0x0020,
    HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH	= 0x0040,
    HB_BUFFER_DIFF_FLAG_POSITION_MISMATCH		= 0x0080
  
  } hb_buffer_diff_flags_t;
  
  /* Compare the contents of two buffers, report types of differences. */
  HB_EXTERN hb_buffer_diff_flags_t
  hb_buffer_diff (hb_buffer_t *buffer,
  		hb_buffer_t *reference,
  		hb_codepoint_t dottedcircle_glyph,
  		unsigned int position_fuzz);
  
  
  /*
   * Tracing.
   */
  
  /**
   * hb_buffer_message_func_t:
   * @buffer: An #hb_buffer_t to work upon
   * @font: The #hb_font_t the @buffer is shaped with
   * @message: `NULL`-terminated message passed to the function
   * @user_data: User data pointer passed by the caller
   *
   * A callback method for #hb_buffer_t. The method gets called with the
   * #hb_buffer_t it was set on, the #hb_font_t the buffer is shaped with and a
   * message describing what step of the shaping process will be performed.
   * Returning `false` from this method will skip this shaping step and move to
   * the next one.
   *
   * Return value: `true` to perform the shaping step, `false` to skip it.
   *
   * Since: 1.1.3
   */
  typedef hb_bool_t	(*hb_buffer_message_func_t)	(hb_buffer_t *buffer,
  							 hb_font_t   *font,
  							 const char  *message,
  							 void        *user_data);
  
  HB_EXTERN void
  hb_buffer_set_message_func (hb_buffer_t *buffer,
  			    hb_buffer_message_func_t func,
  			    void *user_data, hb_destroy_func_t destroy);
  
  
  HB_END_DECLS
  
  #endif /* HB_BUFFER_H */
  

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