ref: 5d651faa702da095f84c805ff013cd1a7869ec31
dir: /include/freetype/ftmm.h/
/**************************************************************************** * * ftmm.h * * FreeType Multiple Master font interface (specification). * * Copyright (C) 1996-2021 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. * */ #ifndef FTMM_H_ #define FTMM_H_ #include <freetype/t1tables.h> FT_BEGIN_HEADER /************************************************************************** * * @section: * multiple_masters * * @title: * Multiple Masters * * @abstract: * How to manage Multiple Masters fonts. * * @description: * The following types and functions are used to manage Multiple Master * fonts, i.e., the selection of specific design instances by setting * design axis coordinates. * * Besides Adobe MM fonts, the interface supports Apple's TrueType GX and * OpenType variation fonts. Some of the routines only work with Adobe * MM fonts, others will work with all three types. They are similar * enough that a consistent interface makes sense. * */ /************************************************************************** * * @struct: * FT_MM_Axis * * @description: * A structure to model a given axis in design space for Multiple Masters * fonts. * * This structure can't be used for TrueType GX or OpenType variation * fonts. * * @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 a Multiple Masters font. * * This structure can't be used for TrueType GX or OpenType variation * fonts. * * @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 Multiple * Masters, TrueType GX, and OpenType variation fonts. * * @fields: * name :: * The axis's name. Not always meaningful for TrueType GX or OpenType * variation fonts. * * 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 variation fonts). 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 variation fonts. Not meaningful for Adobe MM fonts. * * @note: * The fields `minimum`, `def`, and `maximum` are 16.16 fractional values * for TrueType GX and OpenType variation fonts. For Adobe MM fonts, the * values are integers. */ 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 * variation font. * * 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 :: * The entry in 'name' table identifying this instance. * * psid :: * The entry in '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 an Adobe MM, TrueType GX, * or OpenType variation font. * * 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 variation fonts. * * num_designs :: * The number of designs; should be normally 2^num_axis for Adobe MM * fonts. Not meaningful for TrueType GX or OpenType variation fonts * (where every glyph could have a different number of designs). * * num_namedstyles :: * The number of named styles; a 'named style' is a tuple of design * coordinates that has a string ID (in the 'name' table) associated * with it. The font can tell the user that, for example, * [Weight=1.5,Width=1.1] is 'Bold'. Another name for 'named style' is * 'named instance'. * * For Adobe Multiple Masters fonts, this value is always zero because * the format does not support named styles. * * axis :: * An axis descriptor table. TrueType GX and OpenType variation fonts * contain slightly more data than Adobe MM fonts. Memory management * of this pointer is done internally by FreeType. * * namedstyle :: * A named style (instance) table. Only meaningful for TrueType GX and * OpenType variation fonts. 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 variation * fonts. * * @input: * face :: * A handle to the source face. * * @output: * amaster :: * The Multiple Masters 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 variation * fonts. * * @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 will return 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: * [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 will return true). If `num_coords` is zero, * this bit flag gets unset. */ 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. * * @return: * FreeType error code. 0~means success. * * @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 blend * 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 design coordinates array (each element must be between 0 and 1.0 * for Adobe MM fonts, and between -1.0 and 1.0 for TrueType GX and * OpenType variation fonts). * * @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 will return true). If `num_coords` is zero, * this bit flag gets unset. */ 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 blend 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 blend 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 variation * fonts. * * @output: * coords :: * The normalized blend coordinates array. * * @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 variation * fonts. * * @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 Multiple Master fonts limit the number of designs, and thus the * length of the weight vector to~16. * * If `len` is zero and `weightvector` is `NULL`, 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 variation * fonts. * * @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. * * @return: * FreeType error code. 0~means success. * * @note: * Adobe Multiple Master fonts limit the number of designs, and thus the * length of the WeightVector to~16. * * @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 will * return false). * * For Adobe MM fonts (which don't have named instances) this function * simply 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 ); /* */ FT_END_HEADER #endif /* FTMM_H_ */ /* END */