/**************************************************************************** * * ftmm.h * * FreeType variation font interface (specification). * * Copyright (C) 1996-2026 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 #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 */