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Diffstat (limited to 'include/freetype/ftincrem.h')
| -rw-r--r-- | include/freetype/ftincrem.h | 496 |
1 files changed, 279 insertions, 217 deletions
diff --git a/include/freetype/ftincrem.h b/include/freetype/ftincrem.h index 08ce7a95..816581b7 100644 --- a/include/freetype/ftincrem.h +++ b/include/freetype/ftincrem.h @@ -1,205 +1,265 @@ -/***************************************************************************/ -/* */ -/* ftincrem.h */ -/* */ -/* FreeType incremental loading (specification). */ -/* */ -/* Copyright 2002 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 __FTINCREM_H__ -#define __FTINCREM_H__ - -#include <ft2build.h> -#include FT_FREETYPE_H +/**************************************************************************** + * + * ftincrem.h + * + * FreeType incremental loading (specification). + * + * Copyright (C) 2002-2024 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 FTINCREM_H_ +#define FTINCREM_H_ + +#include <freetype/freetype.h> +#include <freetype/ftparams.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: + * incremental + * + * @title: + * Incremental Loading + * + * @abstract: + * Custom Glyph Loading. + * + * @description: + * This section contains various functions used to perform so-called + * 'incremental' glyph loading. This is a mode where all glyphs loaded + * from a given @FT_Face are provided by the client application. + * + * Apart from that, all other tables are loaded normally from the font + * file. This mode is useful when FreeType is used within another + * engine, e.g., a PostScript Imaging Processor. + * + * To enable this mode, you must use @FT_Open_Face, passing an + * @FT_Parameter with the @FT_PARAM_TAG_INCREMENTAL tag and an + * @FT_Incremental_Interface value. See the comments for + * @FT_Incremental_InterfaceRec for an example. + * + */ + - /*************************************************************************** - * - * @type: - * FT_Incremental - * - * @description: - * An opaque type describing a user-provided object used to implement - * "incremental" glyph loading within FreeType. This is used to support - * embedded fonts in certain environments (e.g. Postscript interpreters), - * where the glyph data isn't in the font file, or must be overridden by - * different values. - * - * @note: - * It is up to client applications to create and implement @FT_Incremental - * objects, as long as they provide implementations for the methods - * @FT_Incremental_GetGlyphDataFunc, @FT_Incremental_FreeGlyphDataFunc - * and @FT_Incremental_GetGlyphMetricsFunc. - * - * See the description of @FT_Incremental_InterfaceRec to understand how - * to use incremental objects with FreeType. - */ + /************************************************************************** + * + * @type: + * FT_Incremental + * + * @description: + * An opaque type describing a user-provided object used to implement + * 'incremental' glyph loading within FreeType. This is used to support + * embedded fonts in certain environments (e.g., PostScript + * interpreters), where the glyph data isn't in the font file, or must be + * overridden by different values. + * + * @note: + * It is up to client applications to create and implement + * @FT_Incremental objects, as long as they provide implementations for + * the methods @FT_Incremental_GetGlyphDataFunc, + * @FT_Incremental_FreeGlyphDataFunc and + * @FT_Incremental_GetGlyphMetricsFunc. + * + * See the description of @FT_Incremental_InterfaceRec to understand how + * to use incremental objects with FreeType. + * + */ typedef struct FT_IncrementalRec_* FT_Incremental; - /*************************************************************************** - * - * @struct: - * FT_Incremental_Metrics - * - * @description: - * A small structure used to contain the basic glyph metrics returned - * by the @FT_Incremental_GetGlyphMetricsFunc method. - * - * @fields: - * bearing_x :: - * Left bearing, in font units. - * - * bearing_y :: - * Top bearing, in font units. - * - * advance :: - * Glyph advance, in font units. - * - * @note: - * These correspond to horizontal or vertical metrics depending on the - * value of the 'vertical' argument to the function - * @FT_Incremental_GetGlyphMetricsFunc. - */ + /************************************************************************** + * + * @struct: + * FT_Incremental_MetricsRec + * + * @description: + * A small structure used to contain the basic glyph metrics returned by + * the @FT_Incremental_GetGlyphMetricsFunc method. + * + * @fields: + * bearing_x :: + * Left bearing, in font units. + * + * bearing_y :: + * Top bearing, in font units. + * + * advance :: + * Horizontal component of glyph advance, in font units. + * + * advance_v :: + * Vertical component of glyph advance, in font units. + * + * @note: + * These correspond to horizontal or vertical metrics depending on the + * value of the `vertical` argument to the function + * @FT_Incremental_GetGlyphMetricsFunc. + * + */ typedef struct FT_Incremental_MetricsRec_ { FT_Long bearing_x; FT_Long bearing_y; FT_Long advance; + FT_Long advance_v; /* since 2.3.12 */ + + } FT_Incremental_MetricsRec; + + + /************************************************************************** + * + * @struct: + * FT_Incremental_Metrics + * + * @description: + * A handle to an @FT_Incremental_MetricsRec structure. + * + */ + typedef struct FT_Incremental_MetricsRec_* FT_Incremental_Metrics; - } FT_Incremental_MetricsRec, *FT_Incremental_Metrics; - - - /*************************************************************************** - * - * @type: - * FT_Incremental_GetGlyphDataFunc - * - * @description: - * A function called by FreeType to access a given glyph's data bytes - * during @FT_Load_Glyph or @FT_Load_Char if incremental loading is - * enabled. - * - * Note that the format of the glyph's data bytes depends on the font - * file format. For TrueType, it must correspond to the raw bytes within - * the 'glyf' table. For Postscript formats, it must correspond to the - * *unencrypted* charstring bytes, without any 'lenIV' header. It is - * undefined for any other format. - * - * @input: - * incremental :: - * Handle to an opaque @FT_Incremental handle provided by the client - * application. - * - * glyph_index :: - * Index of relevant glyph. - * - * @output: - * adata :: - * A structure describing the returned glyph data bytes (which will be - * accessed as a read-only byte block). - * - * @return: - * FreeType error code. 0 means success. - * - * @note: - * If this function returns succesfully the method - * @FT_Incremental_FreeGlyphDataFunc will be called later to release - * the data bytes. - * - * Nested calls to @FT_Incremental_GetGlyphDataFunc can happen for - * compound glyphs. - */ + + /************************************************************************** + * + * @type: + * FT_Incremental_GetGlyphDataFunc + * + * @description: + * A function called by FreeType to access a given glyph's data bytes + * during @FT_Load_Glyph or @FT_Load_Char if incremental loading is + * enabled. + * + * Note that the format of the glyph's data bytes depends on the font + * file format. For TrueType, it must correspond to the raw bytes within + * the 'glyf' table. For PostScript formats, it must correspond to the + * **unencrypted** charstring bytes, without any `lenIV` header. It is + * undefined for any other format. + * + * @input: + * incremental :: + * Handle to an opaque @FT_Incremental handle provided by the client + * application. + * + * glyph_index :: + * Index of relevant glyph. + * + * @output: + * adata :: + * A structure describing the returned glyph data bytes (which will be + * accessed as a read-only byte block). + * + * @return: + * FreeType error code. 0~means success. + * + * @note: + * If this function returns successfully the method + * @FT_Incremental_FreeGlyphDataFunc will be called later to release the + * data bytes. + * + * Nested calls to @FT_Incremental_GetGlyphDataFunc can happen for + * compound glyphs. + * + */ typedef FT_Error (*FT_Incremental_GetGlyphDataFunc)( FT_Incremental incremental, FT_UInt glyph_index, FT_Data* adata ); - /*************************************************************************** - * - * @type: - * FT_Incremental_FreeGlyphDataFunc - * - * @description: - * A function used to release the glyph data bytes returned by a - * successful call to @FT_Incremental_GetGlyphDataFunc. - * - * @input: - * incremental :: - * A handle to an opaque @FT_Incremental handle provided by the client - * application. - * - * data :: - * A structure describing the glyph data bytes (which will be accessed - * as a read-only byte block). - */ + /************************************************************************** + * + * @type: + * FT_Incremental_FreeGlyphDataFunc + * + * @description: + * A function used to release the glyph data bytes returned by a + * successful call to @FT_Incremental_GetGlyphDataFunc. + * + * @input: + * incremental :: + * A handle to an opaque @FT_Incremental handle provided by the client + * application. + * + * data :: + * A structure describing the glyph data bytes (which will be accessed + * as a read-only byte block). + * + */ typedef void (*FT_Incremental_FreeGlyphDataFunc)( FT_Incremental incremental, FT_Data* data ); - /*************************************************************************** - * - * @type: - * FT_Incremental_GetGlyphMetricsFunc - * - * @description: - * A function used to retrieve the basic metrics of a given glyph index - * before accessing its data. This is necessary because, in certain - * formats like TrueType, the metrics are stored in a different place from - * the glyph images proper. - * - * @input: - * incremental :: - * A handle to an opaque @FT_Incremental handle provided by the client - * application. - * - * glyph_index :: - * Index of relevant glyph. - * - * vertical :: - * If true, return vertical metrics. - * - * @output: - * ametrics :: - * The glyph metrics in font units. - * - * afound :: - * True if there are metrics at all. - * - */ + /************************************************************************** + * + * @type: + * FT_Incremental_GetGlyphMetricsFunc + * + * @description: + * A function used to retrieve the basic metrics of a given glyph index + * before accessing its data. This allows for handling font types such + * as PCL~XL Format~1, Class~2 downloaded TrueType fonts, where the glyph + * metrics (`hmtx` and `vmtx` tables) are permitted to be omitted from + * the font, and the relevant metrics included in the header of the glyph + * outline data. Importantly, this is not intended to allow custom glyph + * metrics (for example, Postscript Metrics dictionaries), because that + * conflicts with the requirements of outline hinting. Such custom + * metrics must be handled separately, by the calling application. + * + * @input: + * incremental :: + * A handle to an opaque @FT_Incremental handle provided by the client + * application. + * + * glyph_index :: + * Index of relevant glyph. + * + * vertical :: + * If true, return vertical metrics. + * + * ametrics :: + * This parameter is used for both input and output. The original + * glyph metrics, if any, in font units. If metrics are not available + * all the values must be set to zero. + * + * @output: + * ametrics :: + * The glyph metrics in font units. + * + */ typedef FT_Error (*FT_Incremental_GetGlyphMetricsFunc) ( FT_Incremental incremental, FT_UInt glyph_index, FT_Bool vertical, - FT_Incremental_MetricsRec *ametrics, - FT_Bool *afound ); + FT_Incremental_MetricsRec *ametrics ); /************************************************************************** * * @struct: * FT_Incremental_FuncsRec - * + * * @description: - * A table of functions for accessing fonts that load data - * incrementally. Used in @FT_Incremental_Interface. - * + * A table of functions for accessing fonts that load data incrementally. + * Used in @FT_Incremental_InterfaceRec. + * * @fields: * get_glyph_data :: * The function to get glyph data. Must not be null. @@ -208,8 +268,9 @@ FT_BEGIN_HEADER * The function to release glyph data. Must not be null. * * get_glyph_metrics :: - * The function to get glyph metrics. May be null if the font does - * not provide overriding glyph metrics. + * The function to get glyph metrics. May be null if the font does not + * require it. + * */ typedef struct FT_Incremental_FuncsRec_ { @@ -220,67 +281,68 @@ FT_BEGIN_HEADER } FT_Incremental_FuncsRec; - /*************************************************************************** - * - * @struct: - * FT_Incremental_InterfaceRec - * - * @description: - * A structure to be used with @FT_Open_Face to indicate that the user - * wants to support incremental glyph loading. You should use it with - * @FT_PARAM_TAG_INCREMENTAL as in the following example: - * - * { - * FT_Incremental_InterfaceRec inc_int; - * FT_Parameter parameter; - * FT_Open_Args open_args; - * - * - * // set up incremental descriptor - * inc_int.funcs = my_funcs; - * inc_int.object = my_object; - * - * // set up optional parameter - * parameter.tag = FT_PARAM_TAG_INCREMENTAL; - * parameter.data = &inc_int; - * - * // set up FT_Open_Args structure - * open_args.flags = (FT_Open_Flags)( FT_OPEN_PATHNAME | - * FT_OPEN_PARAMS ); - * open_args.pathname = my_font_pathname; - * open_args.num_params = 1; - * open_args.params = ¶meter; // we use one optional argument - * - * // open the font - * error = FT_Open_Face( library, &open_args, index, &face ); - * ... - * } - */ + /************************************************************************** + * + * @struct: + * FT_Incremental_InterfaceRec + * + * @description: + * A structure to be used with @FT_Open_Face to indicate that the user + * wants to support incremental glyph loading. You should use it with + * @FT_PARAM_TAG_INCREMENTAL as in the following example: + * + * ``` + * FT_Incremental_InterfaceRec inc_int; + * FT_Parameter parameter; + * FT_Open_Args open_args; + * + * + * // set up incremental descriptor + * inc_int.funcs = my_funcs; + * inc_int.object = my_object; + * + * // set up optional parameter + * parameter.tag = FT_PARAM_TAG_INCREMENTAL; + * parameter.data = &inc_int; + * + * // set up FT_Open_Args structure + * open_args.flags = FT_OPEN_PATHNAME | FT_OPEN_PARAMS; + * open_args.pathname = my_font_pathname; + * open_args.num_params = 1; + * open_args.params = ¶meter; // we use one optional argument + * + * // open the font + * error = FT_Open_Face( library, &open_args, index, &face ); + * ... + * ``` + * + */ typedef struct FT_Incremental_InterfaceRec_ { const FT_Incremental_FuncsRec* funcs; FT_Incremental object; - + } FT_Incremental_InterfaceRec; - /*************************************************************************** - * - * @constant: - * FT_PARAM_TAG_INCREMENTAL - * - * @description: - * A constant used as the tag of @FT_Parameter structures to indicate - * an incremental loading object to be used by FreeType. - * - */ -#define FT_PARAM_TAG_INCREMENTAL FT_MAKE_TAG( 'i', 'n', 'c', 'r' ) + /************************************************************************** + * + * @type: + * FT_Incremental_Interface + * + * @description: + * A pointer to an @FT_Incremental_InterfaceRec structure. + * + */ + typedef FT_Incremental_InterfaceRec* FT_Incremental_Interface; + + + /* */ - /* */ FT_END_HEADER -#endif /* __FTINCREM_H__ */ +#endif /* FTINCREM_H_ */ /* END */ |