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 /****************************************************************************
  *
  * ftmm.h
  *
  *   FreeType variation font interface (specification).
  *
  * Copyright (C) 1996-2025 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.
  *
  */
 
 
 #ifndef FTMM_H_
 #define FTMM_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:
    *   multiple_masters
    *
    * @title:
    *   OpenType Font Variations, TrueType GX, and Adobe MM Fonts
    *
    * @abstract:
    *   How to manage variable fonts with multiple design axes.
    *
    * @description:
    *   The following types and functions manage OpenType Font Variations,
    *   Adobe Multiple Master (MM) fonts, and Apple TrueType GX fonts.  These
    *   formats have in common that they allow the selection of specific
    *   design instances by setting design coordinates for one or more axes
    *   like font weight or width.
    *
    *   For historical reasons there are two interfaces.  The first, older one
    *   can be used with Adobe MM fonts only, and the second, newer one is a
    *   unified interface that handles all three font formats.  However, some
    *   differences remain and are documented accordingly; in particular,
    *   Adobe MM fonts don't have named instances (see below).
    *
    *   For Adobe MM fonts, macro @FT_IS_SFNT returns false.  For TrueType GX
    *   and OpenType Font Variations, it returns true.
    *
    *   We use mostly the terminology of the OpenType standard.  Here are some
    *   important technical terms.
    *
    *   * A 'named instance' is a tuple of design coordinates that has a
    *     string ID (i.e., an index into the font's 'name' table) associated
    *     with it.  The font can tell the user that, for example,
    *     [Weight=700,Width=110] is 'Bold'.  Another name for 'named instance'
    *     is 'named style'.
    *
    *       Adobe MM fonts don't have named instances.
    *
    *   * The 'default instance' of a variation font is that instance for
    *     which the nth axis coordinate is equal to the nth default axis
    *     coordinate (i.e., `axis[n].def` as specified in the @FT_MM_Var
    *     structure), with~n covering all axes.  In TrueType GX and OpenType
    *     Font Variations, the default instance is explicitly given.  In Adobe
    *     MM fonts, the `WeightVector` entry as found in the font file is
    *     taken as the default instance.
    *
    *       For TrueType GX and OpenType Font Variations, FreeType synthesizes
    *       a named instance for the default instance if the font does not
    *       contain such an entry.
    *
    *   * 'Design coordinates' are the axis values found in a variation font
    *      file.  Their meaning is specified by the font designer and the
    *      values are rather arbitrary.
    *
    *       For example, the 'weight' axis in design coordinates might vary
    *       between 100 (thin) and 900 (heavy) in font~A, while font~B
    *       contains values between 400 (normal) and 800 (extra bold).
    *
    *   * 'Normalized coordinates' are design coordinates mapped to a standard
    *     range; they are also called 'blend coordinates'.
    *
    *       For TrueType GX and OpenType Font Variations, the range is [-1;1],
    *       with the minimum mapped to value~-1, the default mapped to
    *       value~0, and the maximum mapped to value~1, and all other
    *       coordinates mapped to intervening points.  Please look up the
    *       [OpenType
    *       specification](https://learn.microsoft.com/en-us/typography/opentype/spec/otvaroverview)
    *       on how this mapping works in detail.
    *
    *       For Adobe MM fonts, this standard range is [0;1], with the minimum
    *       mapped to value~0 and the maximum mapped to value~1, and all other
    *       coordinates mapped to intervening points.  Please look up [Adobe
    *       TechNote
    *       #5015](https://adobe-type-tools.github.io/font-tech-notes/pdfs/5015.Type1_Supp.pdf)
    *       on how this mapping works in detail.
    *
    *       Assuming that the two fonts in the previous example are OpenType
    *       Font Variations, both font~A's [100;900] and font~B's [400;800]
    *       coordinate ranges get mapped to [-1;1].
    */
 
 
   /**************************************************************************
    *
    * @enum:
    *   T1_MAX_MM_XXX
    *
    * @description:
    *   Adobe MM font limits as defined in their specifications.
    *
    * @values:
    *   T1_MAX_MM_AXIS ::
    *     The maximum number of Adobe MM font axes.
    *
    *   T1_MAX_MM_DESIGNS ::
    *     The maximum number of Adobe MM font designs.
    *
    *   T1_MAX_MM_MAP_POINTS ::
    *     The maximum number of elements in a design map.
    *
    */
 #define T1_MAX_MM_AXIS         4
 #define T1_MAX_MM_DESIGNS     16
 #define T1_MAX_MM_MAP_POINTS  20
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_MM_Axis
    *
    * @description:
    *   A structure to model a given axis in design space for Adobe MM fonts.
    *
    *   This structure can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @fields:
    *   name ::
    *     The axis's name.
    *
    *   minimum ::
    *     The axis's minimum design coordinate.
    *
    *   maximum ::
    *     The axis's maximum design coordinate.
    */
   typedef struct  FT_MM_Axis_
   {
     FT_String*  name;
     FT_Long     minimum;
     FT_Long     maximum;
 
   } FT_MM_Axis;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Multi_Master
    *
    * @description:
    *   A structure to model the axes and space of an Adobe MM font.
    *
    *   This structure can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @fields:
    *   num_axis ::
    *     Number of axes.  Cannot exceed~4.
    *
    *   num_designs ::
    *     Number of designs; should be normally `2^num_axis` even though the
    *     Type~1 specification strangely allows for intermediate designs to be
    *     present.  This number cannot exceed~16.
    *
    *   axis ::
    *     A table of axis descriptors.
    */
   typedef struct  FT_Multi_Master_
   {
     FT_UInt     num_axis;
     FT_UInt     num_designs;
     FT_MM_Axis  axis[T1_MAX_MM_AXIS];
 
   } FT_Multi_Master;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Var_Axis
    *
    * @description:
    *   A structure to model a given axis in design space for Adobe MM fonts,
    *   TrueType GX, and OpenType Font Variations.
    *
    * @fields:
    *   name ::
    *     The axis's name.  Not always meaningful for TrueType GX or OpenType
    *     Font Variations.
    *
    *   minimum ::
    *     The axis's minimum design coordinate.
    *
    *   def ::
    *     The axis's default design coordinate.  FreeType computes meaningful
    *     default values for Adobe MM fonts.
    *
    *   maximum ::
    *     The axis's maximum design coordinate.
    *
    *   tag ::
    *     The axis's tag (the equivalent to 'name' for TrueType GX and
    *     OpenType Font Variations).  FreeType provides default values for
    *     Adobe MM fonts if possible.
    *
    *   strid ::
    *     The axis name entry in the font's 'name' table.  This is another
    *     (and often better) version of the 'name' field for TrueType GX or
    *     OpenType Font Variations.  Not meaningful for Adobe MM fonts.
    *
    * @note:
    *   The fields `minimum`, `def`, and `maximum` are 16.16 fractional values
    *   for TrueType GX and OpenType Font Variations.  For Adobe MM fonts, the
    *   values are whole numbers (i.e., the fractional part is zero).
    */
   typedef struct  FT_Var_Axis_
   {
     FT_String*  name;
 
     FT_Fixed    minimum;
     FT_Fixed    def;
     FT_Fixed    maximum;
 
     FT_ULong    tag;
     FT_UInt     strid;
 
   } FT_Var_Axis;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Var_Named_Style
    *
    * @description:
    *   A structure to model a named instance in a TrueType GX or OpenType
    *   Font Variations.
    *
    *   This structure can't be used for Adobe MM fonts.
    *
    * @fields:
    *   coords ::
    *     The design coordinates for this instance.  This is an array with one
    *     entry for each axis.
    *
    *   strid ::
    *     An index into the 'name' table identifying this instance.
    *
    *   psid ::
    *     An index into the 'name' table identifying a PostScript name for
    *     this instance.  Value 0xFFFF indicates a missing entry.
    */
   typedef struct  FT_Var_Named_Style_
   {
     FT_Fixed*  coords;
     FT_UInt    strid;
     FT_UInt    psid;   /* since 2.7.1 */
 
   } FT_Var_Named_Style;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_MM_Var
    *
    * @description:
    *   A structure to model the axes and space of Adobe MM fonts, TrueType
    *   GX, or OpenType Font Variations.
    *
    *   Some fields are specific to one format and not to the others.
    *
    * @fields:
    *   num_axis ::
    *     The number of axes.  The maximum value is~4 for Adobe MM fonts; no
    *     limit in TrueType GX or OpenType Font Variations.
    *
    *   num_designs ::
    *     The number of designs; should be normally `2^num_axis` for Adobe MM
    *     fonts.  Not meaningful for TrueType GX or OpenType Font Variations
    *     (where every glyph could have a different number of designs).
    *
    *   num_namedstyles ::
    *     The number of named instances.  For Adobe MM fonts, this value is
    *     always zero.
    *
    *   axis ::
    *     An axis descriptor table.  TrueType GX and OpenType Font Variations
    *     contain slightly more data than Adobe MM fonts.  Memory management
    *     of this pointer is done internally by FreeType.
    *
    *   namedstyle ::
    *     An array of named instances.  Only meaningful for TrueType GX and
    *     OpenType Font Variations.  Memory management of this pointer is done
    *     internally by FreeType.
    */
   typedef struct  FT_MM_Var_
   {
     FT_UInt              num_axis;
     FT_UInt              num_designs;
     FT_UInt              num_namedstyles;
     FT_Var_Axis*         axis;
     FT_Var_Named_Style*  namedstyle;
 
   } FT_MM_Var;
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_Multi_Master
    *
    * @description:
    *   Retrieve a variation descriptor of a given Adobe MM font.
    *
    *   This function can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    * @output:
    *   amaster ::
    *     The Adobe MM font's variation descriptor.
    *
    * @return:
    *   FreeType error code.  0~means success.
    */
   FT_EXPORT( FT_Error )
   FT_Get_Multi_Master( FT_Face           face,
                        FT_Multi_Master  *amaster );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_MM_Var
    *
    * @description:
    *   Retrieve a variation descriptor for a given font.
    *
    *   This function works with all supported variation formats.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    * @output:
    *   amaster ::
    *     The variation descriptor.  Allocates a data structure, which the
    *     user must deallocate with a call to @FT_Done_MM_Var after use.
    *
    * @return:
    *   FreeType error code.  0~means success.
    */
   FT_EXPORT( FT_Error )
   FT_Get_MM_Var( FT_Face      face,
                  FT_MM_Var*  *amaster );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Done_MM_Var
    *
    * @description:
    *   Free the memory allocated by @FT_Get_MM_Var.
    *
    * @input:
    *   library ::
    *     A handle of the face's parent library object that was used in the
    *     call to @FT_Get_MM_Var to create `amaster`.
    *
    * @return:
    *   FreeType error code.  0~means success.
    */
   FT_EXPORT( FT_Error )
   FT_Done_MM_Var( FT_Library   library,
                   FT_MM_Var   *amaster );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_MM_Design_Coordinates
    *
    * @description:
    *   For Adobe MM fonts, choose an interpolated font design through design
    *   coordinates.
    *
    *   This function can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @inout:
    *   face ::
    *     A handle to the source face.
    *
    * @input:
    *   num_coords ::
    *     The number of available design coordinates.  If it is larger than
    *     the number of axes, ignore the excess values.  If it is smaller than
    *     the number of axes, use default values for the remaining axes.
    *
    *   coords ::
    *     An array of design coordinates.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   [Since 2.8.1] To reset all axes to the default values, call the
    *   function with `num_coords` set to zero and `coords` set to `NULL`.
    *
    *   [Since 2.9] If `num_coords` is larger than zero, this function sets
    *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
    *   (i.e., @FT_IS_VARIATION returns true).  If `num_coords` is zero, this
    *   bit flag gets unset.
    */
   FT_EXPORT( FT_Error )
   FT_Set_MM_Design_Coordinates( FT_Face   face,
                                 FT_UInt   num_coords,
                                 FT_Long*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_Var_Design_Coordinates
    *
    * @description:
    *   Choose an interpolated font design through design coordinates.
    *
    *   This function works with all supported variation formats.
    *
    * @inout:
    *   face ::
    *     A handle to the source face.
    *
    * @input:
    *   num_coords ::
    *     The number of available design coordinates.  If it is larger than
    *     the number of axes, ignore the excess values.  If it is smaller than
    *     the number of axes, use default values for the remaining axes.
    *
    *   coords ::
    *     An array of design coordinates.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   The design coordinates are 16.16 fractional values for TrueType GX and
    *   OpenType Font Variations.  For Adobe MM fonts, the values are supposed
    *   to be whole numbers (i.e., the fractional part is zero).
    *
    *   [Since 2.8.1] To reset all axes to the default values, call the
    *   function with `num_coords` set to zero and `coords` set to `NULL`.
    *   [Since 2.9] 'Default values' means the currently selected named
    *   instance (or the base font if no named instance is selected).
    *
    *   [Since 2.9] If `num_coords` is larger than zero, this function sets
    *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
    *   (i.e., @FT_IS_VARIATION returns true).  If `num_coords` is zero, this
    *   bit flag gets unset.
    *
    *   [Since 2.14] This function also sets the @FT_FACE_FLAG_VARIATION bit
    *   in @FT_Face's `face_flags` field (i.e., @FT_IS_VARIATION returns
    *   true) if any of the provided coordinates is different from the face's
    *   default value for the corresponding axis, that is, the set up face is
    *   not at its default position.
    */
   FT_EXPORT( FT_Error )
   FT_Set_Var_Design_Coordinates( FT_Face    face,
                                  FT_UInt    num_coords,
                                  FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_Var_Design_Coordinates
    *
    * @description:
    *   Get the design coordinates of the currently selected interpolated
    *   font.
    *
    *   This function works with all supported variation formats.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    *   num_coords ::
    *     The number of design coordinates to retrieve.  If it is larger than
    *     the number of axes, set the excess values to~0.
    *
    * @output:
    *   coords ::
    *     The design coordinates array, which must be allocated by the user.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   The design coordinates are 16.16 fractional values for TrueType GX and
    *   OpenType Font Variations.  For Adobe MM fonts, the values are whole
    *   numbers (i.e., the fractional part is zero).
    *
    * @since:
    *   2.7.1
    */
   FT_EXPORT( FT_Error )
   FT_Get_Var_Design_Coordinates( FT_Face    face,
                                  FT_UInt    num_coords,
                                  FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_MM_Blend_Coordinates
    *
    * @description:
    *   Choose an interpolated font design through normalized coordinates.
    *
    *   This function works with all supported variation formats.
    *
    * @inout:
    *   face ::
    *     A handle to the source face.
    *
    * @input:
    *   num_coords ::
    *     The number of available design coordinates.  If it is larger than
    *     the number of axes, ignore the excess values.  If it is smaller than
    *     the number of axes, use default values for the remaining axes.
    *
    *   coords ::
    *     The normalized coordinates array.  Each element is a 16.16
    *     fractional value and must be between 0 and 1.0 for Adobe MM fonts,
    *     and between -1.0 and 1.0 for TrueType GX and OpenType Font
    *     Variations.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   [Since 2.8.1] To reset all axes to the default values, call the
    *   function with `num_coords` set to zero and `coords` set to `NULL`.
    *   [Since 2.9] 'Default values' means the currently selected named
    *   instance (or the base font if no named instance is selected).
    *
    *   [Since 2.9] If `num_coords` is larger than zero, this function sets
    *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
    *   (i.e., @FT_IS_VARIATION returns true).  If `num_coords` is zero, this
    *   bit flag gets unset.
    *
    *   [Since 2.14] This function also sets the @FT_FACE_FLAG_VARIATION bit
    *   in @FT_Face's `face_flags` field (i.e., @FT_IS_VARIATION returns
    *   true) if any of the provided coordinates is different from the face's
    *   default value for the corresponding axis, that is, the set up face is
    *   not at its default position.
    */
   FT_EXPORT( FT_Error )
   FT_Set_MM_Blend_Coordinates( FT_Face    face,
                                FT_UInt    num_coords,
                                FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_MM_Blend_Coordinates
    *
    * @description:
    *   Get the normalized coordinates of the currently selected interpolated
    *   font.
    *
    *   This function works with all supported variation formats.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    *   num_coords ::
    *     The number of normalized coordinates to retrieve.  If it is larger
    *     than the number of axes, set the excess values to~0.5 for Adobe MM
    *     fonts, and to~0 for TrueType GX and OpenType Font Variations.
    *
    * @output:
    *   coords ::
    *     The normalized coordinates array (as 16.16 fractional values), which
    *     must be allocated by the user.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @since:
    *   2.7.1
    */
   FT_EXPORT( FT_Error )
   FT_Get_MM_Blend_Coordinates( FT_Face    face,
                                FT_UInt    num_coords,
                                FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_Var_Blend_Coordinates
    *
    * @description:
    *   This is another name of @FT_Set_MM_Blend_Coordinates.
    */
   FT_EXPORT( FT_Error )
   FT_Set_Var_Blend_Coordinates( FT_Face    face,
                                 FT_UInt    num_coords,
                                 FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_Var_Blend_Coordinates
    *
    * @description:
    *   This is another name of @FT_Get_MM_Blend_Coordinates.
    *
    * @since:
    *   2.7.1
    */
   FT_EXPORT( FT_Error )
   FT_Get_Var_Blend_Coordinates( FT_Face    face,
                                 FT_UInt    num_coords,
                                 FT_Fixed*  coords );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_MM_WeightVector
    *
    * @description:
    *   For Adobe MM fonts, choose an interpolated font design by directly
    *   setting the weight vector.
    *
    *   This function can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @inout:
    *   face ::
    *     A handle to the source face.
    *
    * @input:
    *   len ::
    *     The length of the weight vector array.  If it is larger than the
    *     number of designs, the extra values are ignored.  If it is less than
    *     the number of designs, the remaining values are set to zero.
    *
    *   weightvector ::
    *     An array representing the weight vector.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   Adobe MM fonts limit the number of designs, and thus the length of the
    *   weight vector, to 16~elements.
    *
    *   If `len` is larger than zero, this function sets the
    *   @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field (i.e.,
    *   @FT_IS_VARIATION returns true).  If `len` is zero, this bit flag is
    *   unset and the weight vector array is reset to the default values.
    *
    *   The Adobe documentation also states that the values in the
    *   `WeightVector` array must total 1.0 +/-~0.001.  In practice this does
    *   not seem to be enforced, so is not enforced here, either.
    *
    * @since:
    *   2.10
    */
   FT_EXPORT( FT_Error )
   FT_Set_MM_WeightVector( FT_Face    face,
                           FT_UInt    len,
                           FT_Fixed*  weightvector );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_MM_WeightVector
    *
    * @description:
    *   For Adobe MM fonts, retrieve the current weight vector of the font.
    *
    *   This function can't be used with TrueType GX or OpenType Font
    *   Variations.
    *
    * @inout:
    *   face ::
    *     A handle to the source face.
    *
    *   len ::
    *     A pointer to the size of the array to be filled.  If the size of the
    *     array is less than the number of designs, `FT_Err_Invalid_Argument`
    *     is returned, and `len` is set to the required size (the number of
    *     designs).  If the size of the array is greater than the number of
    *     designs, the remaining entries are set to~0.  On successful
    *     completion, `len` is set to the number of designs (i.e., the number
    *     of values written to the array).
    *
    * @output:
    *   weightvector ::
    *     An array to be filled; it must be allocated by the user.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   Adobe MM fonts limit the number of designs, and thus the length of the
    *   weight vector, to~16 elements.
    *
    * @since:
    *   2.10
    */
   FT_EXPORT( FT_Error )
   FT_Get_MM_WeightVector( FT_Face    face,
                           FT_UInt*   len,
                           FT_Fixed*  weightvector );
 
 
   /**************************************************************************
    *
    * @enum:
    *   FT_VAR_AXIS_FLAG_XXX
    *
    * @description:
    *   A list of bit flags used in the return value of
    *   @FT_Get_Var_Axis_Flags.
    *
    * @values:
    *   FT_VAR_AXIS_FLAG_HIDDEN ::
    *     The variation axis should not be exposed to user interfaces.
    *
    * @since:
    *   2.8.1
    */
 #define FT_VAR_AXIS_FLAG_HIDDEN  1
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_Var_Axis_Flags
    *
    * @description:
    *   Get the 'flags' field of an OpenType Variation Axis Record.
    *
    *   Not meaningful for Adobe MM fonts (`*flags` is always zero).
    *
    * @input:
    *   master ::
    *     The variation descriptor.
    *
    *   axis_index ::
    *     The index of the requested variation axis.
    *
    * @output:
    *   flags ::
    *     The 'flags' field.  See @FT_VAR_AXIS_FLAG_XXX for possible values.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @since:
    *   2.8.1
    */
   FT_EXPORT( FT_Error )
   FT_Get_Var_Axis_Flags( FT_MM_Var*  master,
                          FT_UInt     axis_index,
                          FT_UInt*    flags );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Set_Named_Instance
    *
    * @description:
    *   Set or change the current named instance.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    *   instance_index ::
    *     The index of the requested instance, starting with value~1.  If set
    *     to value~0, FreeType switches to font access without a named
    *     instance.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   The function uses the value of `instance_index` to set bits 16-30 of
    *   the face's `face_index` field.  It also resets any variation applied
    *   to the font, and the @FT_FACE_FLAG_VARIATION bit of the face's
    *   `face_flags` field gets reset to zero (i.e., @FT_IS_VARIATION returns
    *   false).
    *
    *   For Adobe MM fonts, this function resets the current face to the
    *   default instance.
    *
    * @since:
    *   2.9
    */
   FT_EXPORT( FT_Error )
   FT_Set_Named_Instance( FT_Face  face,
                          FT_UInt  instance_index );
 
 
   /**************************************************************************
    *
    * @function:
    *   FT_Get_Default_Named_Instance
    *
    * @description:
    *   Retrieve the index of the default named instance, to be used with
    *   @FT_Set_Named_Instance.
    *
    *   FreeType synthesizes a named instance for the default instance if the
    *   font does not contain such an entry.
    *
    * @input:
    *   face ::
    *     A handle to the source face.
    *
    * @output:
    *   instance_index ::
    *     The index of the default named instance.
    *
    * @return:
    *   FreeType error code.  0~means success.
    *
    * @note:
    *   For Adobe MM fonts, this function always returns zero for
    *   `instance_index`.
    *
    * @since:
    *   2.13.1
    */
   FT_EXPORT( FT_Error )
   FT_Get_Default_Named_Instance( FT_Face   face,
                                  FT_UInt  *instance_index );
 
   /* */
 
 
 FT_END_HEADER
 
 #endif /* FTMM_H_ */
 
 
 /* END */

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