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/****************************************************************************
*
* freetype.h
*
* FreeType high-level API and common types (specification only).
*
* Copyright (C) 1996-2020 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 FREETYPE_H_
#define FREETYPE_H_
#include <ft2build.h>
#include FT_CONFIG_CONFIG_H
#include <freetype/fttypes.h>
#include <freetype/fterrors.h>
FT_BEGIN_HEADER
/**************************************************************************
*
* @section:
* header_inclusion
*
* @title:
* FreeType's header inclusion scheme
*
* @abstract:
* How client applications should include FreeType header files.
*
* @description:
* To be as flexible as possible (and for historical reasons), you must
* load file `ft2build.h` first before other header files, for example
*
* ```
* #include <ft2build.h>
*
* #include <freetype/freetype.h>
* #include <freetype/ftoutln.h>
* ```
*/
/**************************************************************************
*
* @section:
* user_allocation
*
* @title:
* User allocation
*
* @abstract:
* How client applications should allocate FreeType data structures.
*
* @description:
* FreeType assumes that structures allocated by the user and passed as
* arguments are zeroed out except for the actual data. In other words,
* it is recommended to use `calloc` (or variants of it) instead of
* `malloc` for allocation.
*
*/
/*************************************************************************/
/*************************************************************************/
/* */
/* B A S I C T Y P E S */
/* */
/*************************************************************************/
/*************************************************************************/
/**************************************************************************
*
* @section:
* base_interface
*
* @title:
* Base Interface
*
* @abstract:
* The FreeType~2 base font interface.
*
* @description:
* This section describes the most important public high-level API
* functions of FreeType~2.
*
* @order:
* FT_Library
* FT_Face
* FT_Size
* FT_GlyphSlot
* FT_CharMap
* FT_Encoding
* FT_ENC_TAG
*
* FT_FaceRec
*
* FT_FACE_FLAG_SCALABLE
* FT_FACE_FLAG_FIXED_SIZES
* FT_FACE_FLAG_FIXED_WIDTH
* FT_FACE_FLAG_HORIZONTAL
* FT_FACE_FLAG_VERTICAL
* FT_FACE_FLAG_COLOR
* FT_FACE_FLAG_SFNT
* FT_FACE_FLAG_CID_KEYED
* FT_FACE_FLAG_TRICKY
* FT_FACE_FLAG_KERNING
* FT_FACE_FLAG_MULTIPLE_MASTERS
* FT_FACE_FLAG_VARIATION
* FT_FACE_FLAG_GLYPH_NAMES
* FT_FACE_FLAG_EXTERNAL_STREAM
* FT_FACE_FLAG_HINTER
*
* FT_HAS_HORIZONTAL
* FT_HAS_VERTICAL
* FT_HAS_KERNING
* FT_HAS_FIXED_SIZES
* FT_HAS_GLYPH_NAMES
* FT_HAS_COLOR
* FT_HAS_MULTIPLE_MASTERS
*
* FT_IS_SFNT
* FT_IS_SCALABLE
* FT_IS_FIXED_WIDTH
* FT_IS_CID_KEYED
* FT_IS_TRICKY
* FT_IS_NAMED_INSTANCE
* FT_IS_VARIATION
*
* FT_STYLE_FLAG_BOLD
* FT_STYLE_FLAG_ITALIC
*
* FT_SizeRec
* FT_Size_Metrics
*
* FT_GlyphSlotRec
* FT_Glyph_Metrics
* FT_SubGlyph
*
* FT_Bitmap_Size
*
* FT_Init_FreeType
* FT_Done_FreeType
*
* FT_New_Face
* FT_Done_Face
* FT_Reference_Face
* FT_New_Memory_Face
* FT_Face_Properties
* FT_Open_Face
* FT_Open_Args
* FT_Parameter
* FT_Attach_File
* FT_Attach_Stream
*
* FT_Set_Char_Size
* FT_Set_Pixel_Sizes
* FT_Request_Size
* FT_Select_Size
* FT_Size_Request_Type
* FT_Size_RequestRec
* FT_Size_Request
* FT_Set_Transform
* FT_Load_Glyph
* FT_Get_Char_Index
* FT_Get_First_Char
* FT_Get_Next_Char
* FT_Get_Name_Index
* FT_Load_Char
*
* FT_OPEN_MEMORY
* FT_OPEN_STREAM
* FT_OPEN_PATHNAME
* FT_OPEN_DRIVER
* FT_OPEN_PARAMS
*
* FT_LOAD_DEFAULT
* FT_LOAD_RENDER
* FT_LOAD_MONOCHROME
* FT_LOAD_LINEAR_DESIGN
* FT_LOAD_NO_SCALE
* FT_LOAD_NO_HINTING
* FT_LOAD_NO_BITMAP
* FT_LOAD_NO_AUTOHINT
* FT_LOAD_COLOR
*
* FT_LOAD_VERTICAL_LAYOUT
* FT_LOAD_IGNORE_TRANSFORM
* FT_LOAD_FORCE_AUTOHINT
* FT_LOAD_NO_RECURSE
* FT_LOAD_PEDANTIC
*
* FT_LOAD_TARGET_NORMAL
* FT_LOAD_TARGET_LIGHT
* FT_LOAD_TARGET_MONO
* FT_LOAD_TARGET_LCD
* FT_LOAD_TARGET_LCD_V
*
* FT_LOAD_TARGET_MODE
*
* FT_Render_Glyph
* FT_Render_Mode
* FT_Get_Kerning
* FT_Kerning_Mode
* FT_Get_Track_Kerning
* FT_Get_Glyph_Name
* FT_Get_Postscript_Name
*
* FT_CharMapRec
* FT_Select_Charmap
* FT_Set_Charmap
* FT_Get_Charmap_Index
*
* FT_Get_FSType_Flags
* FT_Get_SubGlyph_Info
*
* FT_Face_Internal
* FT_Size_Internal
* FT_Slot_Internal
*
* FT_FACE_FLAG_XXX
* FT_STYLE_FLAG_XXX
* FT_OPEN_XXX
* FT_LOAD_XXX
* FT_LOAD_TARGET_XXX
* FT_SUBGLYPH_FLAG_XXX
* FT_FSTYPE_XXX
*
* FT_HAS_FAST_GLYPHS
*
*/
/**************************************************************************
*
* @struct:
* FT_Glyph_Metrics
*
* @description:
* A structure to model the metrics of a single glyph. The values are
* expressed in 26.6 fractional pixel format; if the flag
* @FT_LOAD_NO_SCALE has been used while loading the glyph, values are
* expressed in font units instead.
*
* @fields:
* width ::
* The glyph's width.
*
* height ::
* The glyph's height.
*
* horiBearingX ::
* Left side bearing for horizontal layout.
*
* horiBearingY ::
* Top side bearing for horizontal layout.
*
* horiAdvance ::
* Advance width for horizontal layout.
*
* vertBearingX ::
* Left side bearing for vertical layout.
*
* vertBearingY ::
* Top side bearing for vertical layout. Larger positive values mean
* further below the vertical glyph origin.
*
* vertAdvance ::
* Advance height for vertical layout. Positive values mean the glyph
* has a positive advance downward.
*
* @note:
* If not disabled with @FT_LOAD_NO_HINTING, the values represent
* dimensions of the hinted glyph (in case hinting is applicable).
*
* Stroking a glyph with an outside border does not increase
* `horiAdvance` or `vertAdvance`; you have to manually adjust these
* values to account for the added width and height.
*
* FreeType doesn't use the 'VORG' table data for CFF fonts because it
* doesn't have an interface to quickly retrieve the glyph height. The
* y~coordinate of the vertical origin can be simply computed as
* `vertBearingY + height` after loading a glyph.
*/
typedef struct FT_Glyph_Metrics_
{
FT_Pos width;
FT_Pos height;
FT_Pos horiBearingX;
FT_Pos horiBearingY;
FT_Pos horiAdvance;
FT_Pos vertBearingX;
FT_Pos vertBearingY;
FT_Pos vertAdvance;
} FT_Glyph_Metrics;
/**************************************************************************
*
* @struct:
* FT_Bitmap_Size
*
* @description:
* This structure models the metrics of a bitmap strike (i.e., a set of
* glyphs for a given point size and resolution) in a bitmap font. It is
* used for the `available_sizes` field of @FT_Face.
*
* @fields:
* height ::
* The vertical distance, in pixels, between two consecutive baselines.
* It is always positive.
*
* width ::
* The average width, in pixels, of all glyphs in the strike.
*
* size ::
* The nominal size of the strike in 26.6 fractional points. This
* field is not very useful.
*
* x_ppem ::
* The horizontal ppem (nominal width) in 26.6 fractional pixels.
*
* y_ppem ::
* The vertical ppem (nominal height) in 26.6 fractional pixels.
*
* @note:
* Windows FNT:
* The nominal size given in a FNT font is not reliable. If the driver
* finds it incorrect, it sets `size` to some calculated values, and
* `x_ppem` and `y_ppem` to the pixel width and height given in the
* font, respectively.
*
* TrueType embedded bitmaps:
* `size`, `width`, and `height` values are not contained in the bitmap
* strike itself. They are computed from the global font parameters.
*/
typedef struct FT_Bitmap_Size_
{
FT_Short height;
FT_Short width;
FT_Pos size;
FT_Pos x_ppem;
FT_Pos y_ppem;
} FT_Bitmap_Size;
/*************************************************************************/
/*************************************************************************/
/* */
/* O B J E C T C L A S S E S */
/* */
/*************************************************************************/
/*************************************************************************/
/**************************************************************************
*
* @type:
* FT_Library
*
* @description:
* A handle to a FreeType library instance. Each 'library' is completely
* independent from the others; it is the 'root' of a set of objects like
* fonts, faces, sizes, etc.
*
* It also embeds a memory manager (see @FT_Memory), as well as a
* scan-line converter object (see @FT_Raster).
*
* [Since 2.5.6] In multi-threaded applications it is easiest to use one
* `FT_Library` object per thread. In case this is too cumbersome, a
* single `FT_Library` object across threads is possible also, as long as
* a mutex lock is used around @FT_New_Face and @FT_Done_Face.
*
* @note:
* Library objects are normally created by @FT_Init_FreeType, and
* destroyed with @FT_Done_FreeType. If you need reference-counting
* (cf. @FT_Reference_Library), use @FT_New_Library and @FT_Done_Library.
*/
typedef struct FT_LibraryRec_ *FT_Library;
/**************************************************************************
*
* @section:
* module_management
*
*/
/**************************************************************************
*
* @type:
* FT_Module
*
* @description:
* A handle to a given FreeType module object. A module can be a font
* driver, a renderer, or anything else that provides services to the
* former.
*/
typedef struct FT_ModuleRec_* FT_Module;
/**************************************************************************
*
* @type:
* FT_Driver
*
* @description:
* A handle to a given FreeType font driver object. A font driver is a
* module capable of creating faces from font files.
*/
typedef struct FT_DriverRec_* FT_Driver;
/**************************************************************************
*
* @type:
* FT_Renderer
*
* @description:
* A handle to a given FreeType renderer. A renderer is a module in
* charge of converting a glyph's outline image to a bitmap. It supports
* a single glyph image format, and one or more target surface depths.
*/
typedef struct FT_RendererRec_* FT_Renderer;
/**************************************************************************
*
* @section:
* base_interface
*
*/
/**************************************************************************
*
* @type:
* FT_Face
*
* @description:
* A handle to a typographic face object. A face object models a given
* typeface, in a given style.
*
* @note:
* A face object also owns a single @FT_GlyphSlot object, as well as one
* or more @FT_Size objects.
*
* Use @FT_New_Face or @FT_Open_Face to create a new face object from a
* given filepath or a custom input stream.
*
* Use @FT_Done_Face to destroy it (along with its slot and sizes).
*
* An `FT_Face` object can only be safely used from one thread at a time.
* Similarly, creation and destruction of `FT_Face` with the same
* @FT_Library object can only be done from one thread at a time. On the
* other hand, functions like @FT_Load_Glyph and its siblings are
* thread-safe and do not need the lock to be held as long as the same
* `FT_Face` object is not used from multiple threads at the same time.
*
* @also:
* See @FT_FaceRec for the publicly accessible fields of a given face
* object.
*/
typedef struct FT_FaceRec_* FT_Face;
/**************************************************************************
*
* @type:
* FT_Size
*
* @description:
* A handle to an object that models a face scaled to a given character
* size.
*
* @note:
* An @FT_Face has one _active_ @FT_Size object that is used by functions
* like @FT_Load_Glyph to determine the scaling transformation that in
* turn is used to load and hint glyphs and metrics.
*
* You can use @FT_Set_Char_Size, @FT_Set_Pixel_Sizes, @FT_Request_Size
* or even @FT_Select_Size to change the content (i.e., the scaling
* values) of the active @FT_Size.
*
* You can use @FT_New_Size to create additional size objects for a given
* @FT_Face, but they won't be used by other functions until you activate
* it through @FT_Activate_Size. Only one size can be activated at any
* given time per face.
*
* @also:
* See @FT_SizeRec for the publicly accessible fields of a given size
* object.
*/
typedef struct FT_SizeRec_* FT_Size;
/**************************************************************************
*
* @type:
* FT_GlyphSlot
*
* @description:
* A handle to a given 'glyph slot'. A slot is a container that can hold
* any of the glyphs contained in its parent face.
*
* In other words, each time you call @FT_Load_Glyph or @FT_Load_Char,
* the slot's content is erased by the new glyph data, i.e., the glyph's
* metrics, its image (bitmap or outline), and other control information.
*
* @also:
* See @FT_GlyphSlotRec for the publicly accessible glyph fields.
*/
typedef struct FT_GlyphSlotRec_* FT_GlyphSlot;
/**************************************************************************
*
* @type:
* FT_CharMap
*
* @description:
* A handle to a character map (usually abbreviated to 'charmap'). A
* charmap is used to translate character codes in a given encoding into
* glyph indexes for its parent's face. Some font formats may provide
* several charmaps per font.
*
* Each face object owns zero or more charmaps, but only one of them can
* be 'active', providing the data used by @FT_Get_Char_Index or
* @FT_Load_Char.
*
* The list of available charmaps in a face is available through the
* `face->num_charmaps` and `face->charmaps` fields of @FT_FaceRec.
*
* The currently active charmap is available as `face->charmap`. You
* should call @FT_Set_Charmap to change it.
*
* @note:
* When a new face is created (either through @FT_New_Face or
* @FT_Open_Face), the library looks for a Unicode charmap within the
* list and automatically activates it. If there is no Unicode charmap,
* FreeType doesn't set an 'active' charmap.
*
* @also:
* See @FT_CharMapRec for the publicly accessible fields of a given
* character map.
*/
typedef struct FT_CharMapRec_* FT_CharMap;
/**************************************************************************
*
* @macro:
* FT_ENC_TAG
*
* @description:
* This macro converts four-letter tags into an unsigned long. It is
* used to define 'encoding' identifiers (see @FT_Encoding).
*
* @note:
* Since many 16-bit compilers don't like 32-bit enumerations, you should
* redefine this macro in case of problems to something like this:
*
* ```
* #define FT_ENC_TAG( value, a, b, c, d ) value
* ```
*
* to get a simple enumeration without assigning special numbers.
*/
#ifndef FT_ENC_TAG
#define FT_ENC_TAG( value, a, b, c, d ) \
value = ( ( (FT_UInt32)(a) << 24 ) | \
( (FT_UInt32)(b) << 16 ) | \
( (FT_UInt32)(c) << 8 ) | \
(FT_UInt32)(d) )
#endif /* FT_ENC_TAG */
/**************************************************************************
*
* @enum:
* FT_Encoding
*
* @description:
* An enumeration to specify character sets supported by charmaps. Used
* in the @FT_Select_Charmap API function.
*
* @note:
* Despite the name, this enumeration lists specific character
* repertories (i.e., charsets), and not text encoding methods (e.g.,
* UTF-8, UTF-16, etc.).
*
* Other encodings might be defined in the future.
*
* @values:
* FT_ENCODING_NONE ::
* The encoding value~0 is reserved for all formats except BDF, PCF,
* and Windows FNT; see below for more information.
*
* FT_ENCODING_UNICODE ::
* The Unicode character set. This value covers all versions of the
* Unicode repertoire, including ASCII and Latin-1. Most fonts include
* a Unicode charmap, but not all of them.
*
* For example, if you want to access Unicode value U+1F028 (and the
* font contains it), use value 0x1F028 as the input value for
* @FT_Get_Char_Index.
*
* FT_ENCODING_MS_SYMBOL ::
* Microsoft Symbol encoding, used to encode mathematical symbols and
* wingdings. For more information, see
* 'https://www.microsoft.com/typography/otspec/recom.htm#non-standard-symbol-fonts',
* 'http://www.kostis.net/charsets/symbol.htm', and
* 'http://www.kostis.net/charsets/wingding.htm'.
*
* This encoding uses character codes from the PUA (Private Unicode
* Area) in the range U+F020-U+F0FF.
*
* FT_ENCODING_SJIS ::
* Shift JIS encoding for Japanese. More info at
* 'https://en.wikipedia.org/wiki/Shift_JIS'. See note on multi-byte
* encodings below.
*
* FT_ENCODING_PRC ::
* Corresponds to encoding systems mainly for Simplified Chinese as
* used in People's Republic of China (PRC). The encoding layout is
* based on GB~2312 and its supersets GBK and GB~18030.
*
* FT_ENCODING_BIG5 ::
* Corresponds to an encoding system for Traditional Chinese as used in
* Taiwan and Hong Kong.
*
* FT_ENCODING_WANSUNG ::
* Corresponds to the Korean encoding system known as Extended Wansung
* (MS Windows code page 949). For more information see
* 'https://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WindowsBestFit/bestfit949.txt'.
*
* FT_ENCODING_JOHAB ::
* The Korean standard character set (KS~C 5601-1992), which
* corresponds to MS Windows code page 1361. This character set
* includes all possible Hangul character combinations.
*
* FT_ENCODING_ADOBE_LATIN_1 ::
* Corresponds to a Latin-1 encoding as defined in a Type~1 PostScript
* font. It is limited to 256 character codes.
*
* FT_ENCODING_ADOBE_STANDARD ::
* Adobe Standard encoding, as found in Type~1, CFF, and OpenType/CFF
* fonts. It is limited to 256 character codes.
*
* FT_ENCODING_ADOBE_EXPERT ::
* Adobe Expert encoding, as found in Type~1, CFF, and OpenType/CFF
* fonts. It is limited to 256 character codes.
*
* FT_ENCODING_ADOBE_CUSTOM ::
* Corresponds to a custom encoding, as found in Type~1, CFF, and
* OpenType/CFF fonts. It is limited to 256 character codes.
*
* FT_ENCODING_APPLE_ROMAN ::
* Apple roman encoding. Many TrueType and OpenType fonts contain a
* charmap for this 8-bit encoding, since older versions of Mac OS are
* able to use it.
*
* FT_ENCODING_OLD_LATIN_2 ::
* This value is deprecated and was neither used nor reported by
* FreeType. Don't use or test for it.
*
* FT_ENCODING_MS_SJIS ::
* Same as FT_ENCODING_SJIS. Deprecated.
*
* FT_ENCODING_MS_GB2312 ::
* Same as FT_ENCODING_PRC. Deprecated.
*
* FT_ENCODING_MS_BIG5 ::
* Same as FT_ENCODING_BIG5. Deprecated.
*
* FT_ENCODING_MS_WANSUNG ::
* Same as FT_ENCODING_WANSUNG. Deprecated.
*
* FT_ENCODING_MS_JOHAB ::
* Same as FT_ENCODING_JOHAB. Deprecated.
*
* @note:
* By default, FreeType enables a Unicode charmap and tags it with
* `FT_ENCODING_UNICODE` when it is either provided or can be generated
* from PostScript glyph name dictionaries in the font file. All other
* encodings are considered legacy and tagged only if explicitly defined
* in the font file. Otherwise, `FT_ENCODING_NONE` is used.
*
* `FT_ENCODING_NONE` is set by the BDF and PCF drivers if the charmap is
* neither Unicode nor ISO-8859-1 (otherwise it is set to
* `FT_ENCODING_UNICODE`). Use @FT_Get_BDF_Charset_ID to find out which
* encoding is really present. If, for example, the `cs_registry` field
* is 'KOI8' and the `cs_encoding` field is 'R', the font is encoded in
* KOI8-R.
*
* `FT_ENCODING_NONE` is always set (with a single exception) by the
* winfonts driver. Use @FT_Get_WinFNT_Header and examine the `charset`
* field of the @FT_WinFNT_HeaderRec structure to find out which encoding
* is really present. For example, @FT_WinFNT_ID_CP1251 (204) means
* Windows code page 1251 (for Russian).
*
* `FT_ENCODING_NONE` is set if `platform_id` is @TT_PLATFORM_MACINTOSH
* and `encoding_id` is not `TT_MAC_ID_ROMAN` (otherwise it is set to
* `FT_ENCODING_APPLE_ROMAN`).
*
* If `platform_id` is @TT_PLATFORM_MACINTOSH, use the function
* @FT_Get_CMap_Language_ID to query the Mac language ID that may be
* needed to be able to distinguish Apple encoding variants. See
*
* https://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/Readme.txt
*
* to get an idea how to do that. Basically, if the language ID is~0,
* don't use it, otherwise subtract 1 from the language ID. Then examine
* `encoding_id`. If, for example, `encoding_id` is `TT_MAC_ID_ROMAN`
* and the language ID (minus~1) is `TT_MAC_LANGID_GREEK`, it is the
* Greek encoding, not Roman. `TT_MAC_ID_ARABIC` with
* `TT_MAC_LANGID_FARSI` means the Farsi variant the Arabic encoding.
*/
typedef enum FT_Encoding_
{
FT_ENC_TAG( FT_ENCODING_NONE, 0, 0, 0, 0 ),
FT_ENC_TAG( FT_ENCODING_MS_SYMBOL, 's', 'y', 'm', 'b' ),
FT_ENC_TAG( FT_ENCODING_UNICODE, 'u', 'n', 'i', 'c' ),
FT_ENC_TAG( FT_ENCODING_SJIS, 's', 'j', 'i', 's' ),
FT_ENC_TAG( FT_ENCODING_PRC, 'g', 'b', ' ', ' ' ),
FT_ENC_TAG( FT_ENCODING_BIG5, 'b', 'i', 'g', '5' ),
FT_ENC_TAG( FT_ENCODING_WANSUNG, 'w', 'a', 'n', 's' ),
FT_ENC_TAG( FT_ENCODING_JOHAB, 'j', 'o', 'h', 'a' ),
/* for backward compatibility */
FT_ENCODING_GB2312 = FT_ENCODING_PRC,
FT_ENCODING_MS_SJIS = FT_ENCODING_SJIS,
FT_ENCODING_MS_GB2312 = FT_ENCODING_PRC,
FT_ENCODING_MS_BIG5 = FT_ENCODING_BIG5,
FT_ENCODING_MS_WANSUNG = FT_ENCODING_WANSUNG,
FT_ENCODING_MS_JOHAB = FT_ENCODING_JOHAB,
FT_ENC_TAG( FT_ENCODING_ADOBE_STANDARD, 'A', 'D', 'O', 'B' ),
FT_ENC_TAG( FT_ENCODING_ADOBE_EXPERT, 'A', 'D', 'B', 'E' ),
FT_ENC_TAG( FT_ENCODING_ADOBE_CUSTOM, 'A', 'D', 'B', 'C' ),
FT_ENC_TAG( FT_ENCODING_ADOBE_LATIN_1, 'l', 'a', 't', '1' ),
FT_ENC_TAG( FT_ENCODING_OLD_LATIN_2, 'l', 'a', 't', '2' ),
FT_ENC_TAG( FT_ENCODING_APPLE_ROMAN, 'a', 'r', 'm', 'n' )
} FT_Encoding;
/* these constants are deprecated; use the corresponding `FT_Encoding` */
/* values instead */
#define ft_encoding_none FT_ENCODING_NONE
#define ft_encoding_unicode FT_ENCODING_UNICODE
#define ft_encoding_symbol FT_ENCODING_MS_SYMBOL
#define ft_encoding_latin_1 FT_ENCODING_ADOBE_LATIN_1
#define ft_encoding_latin_2 FT_ENCODING_OLD_LATIN_2
#define ft_encoding_sjis FT_ENCODING_SJIS
#define ft_encoding_gb2312 FT_ENCODING_PRC
#define ft_encoding_big5 FT_ENCODING_BIG5
#define ft_encoding_wansung FT_ENCODING_WANSUNG
#define ft_encoding_johab FT_ENCODING_JOHAB
#define ft_encoding_adobe_standard FT_ENCODING_ADOBE_STANDARD
#define ft_encoding_adobe_expert FT_ENCODING_ADOBE_EXPERT
#define ft_encoding_adobe_custom FT_ENCODING_ADOBE_CUSTOM
#define ft_encoding_apple_roman FT_ENCODING_APPLE_ROMAN
/**************************************************************************
*
* @struct:
* FT_CharMapRec
*
* @description:
* The base charmap structure.
*
* @fields:
* face ::
* A handle to the parent face object.
*
* encoding ::
* An @FT_Encoding tag identifying the charmap. Use this with
* @FT_Select_Charmap.
*
* platform_id ::
* An ID number describing the platform for the following encoding ID.
* This comes directly from the TrueType specification and gets
* emulated for other formats.
*
* encoding_id ::
* A platform-specific encoding number. This also comes from the
* TrueType specification and gets emulated similarly.
*/
typedef struct FT_CharMapRec_
{
FT_Face face;
FT_Encoding encoding;
FT_UShort platform_id;
FT_UShort encoding_id;
} FT_CharMapRec;
/*************************************************************************/
/*************************************************************************/
/* */
/* B A S E O B J E C T C L A S S E S */
/* */
/*************************************************************************/
/*************************************************************************/
/**************************************************************************
*
* @type:
* FT_Face_Internal
*
* @description:
* An opaque handle to an `FT_Face_InternalRec` structure that models the
* private data of a given @FT_Face object.
*
* This structure might change between releases of FreeType~2 and is not
* generally available to client applications.
*/
typedef struct FT_Face_InternalRec_* FT_Face_Internal;
/**************************************************************************
*
* @struct:
* FT_FaceRec
*
* @description:
* FreeType root face class structure. A face object models a typeface
* in a font file.
*
* @fields:
* num_faces ::
* The number of faces in the font file. Some font formats can have
* multiple faces in a single font file.
*
* face_index ::
* This field holds two different values. Bits 0-15 are the index of
* the face in the font file (starting with value~0). They are set
* to~0 if there is only one face in the font file.
*
* [Since 2.6.1] Bits 16-30 are relevant to GX and OpenType variation
* fonts only, holding the named instance index for the current face
* index (starting with value~1; value~0 indicates font access without
* a named instance). For non-variation fonts, bits 16-30 are ignored.
* If we have the third named instance of face~4, say, `face_index` is
* set to 0x00030004.
*
* Bit 31 is always zero (this is, `face_index` is always a positive
* value).
*
* [Since 2.9] Changing the design coordinates with
* @FT_Set_Var_Design_Coordinates or @FT_Set_Var_Blend_Coordinates does
* not influence the named instance index value (only
* @FT_Set_Named_Instance does that).
*
* face_flags ::
* A set of bit flags that give important information about the face;
* see @FT_FACE_FLAG_XXX for the details.
*
* style_flags ::
* The lower 16~bits contain a set of bit flags indicating the style of
* the face; see @FT_STYLE_FLAG_XXX for the details.
*
* [Since 2.6.1] Bits 16-30 hold the number of named instances
* available for the current face if we have a GX or OpenType variation
* (sub)font. Bit 31 is always zero (this is, `style_flags` is always
* a positive value). Note that a variation font has always at least
* one named instance, namely the default instance.
*
* num_glyphs ::
* The number of glyphs in the face. If the face is scalable and has
* sbits (see `num_fixed_sizes`), it is set to the number of outline
* glyphs.
*
* For CID-keyed fonts (not in an SFNT wrapper) this value gives the
* highest CID used in the font.
*
* family_name ::
* The face's family name. This is an ASCII string, usually in
* English, that describes the typeface's family (like 'Times New
* Roman', 'Bodoni', 'Garamond', etc). This is a least common
* denominator used to list fonts. Some formats (TrueType & OpenType)
* provide localized and Unicode versions of this string. Applications
* should use the format-specific interface to access them. Can be
* `NULL` (e.g., in fonts embedded in a PDF file).
*
* In case the font doesn't provide a specific family name entry,
* FreeType tries to synthesize one, deriving it from other name
* entries.
*
* style_name ::
* The face's style name. This is an ASCII string, usually in English,
* that describes the typeface's style (like 'Italic', 'Bold',
* 'Condensed', etc). Not all font formats provide a style name, so
* this field is optional, and can be set to `NULL`. As for
* `family_name`, some formats provide localized and Unicode versions
* of this string. Applications should use the format-specific
* interface to access them.
*
* num_fixed_sizes ::
* The number of bitmap strikes in the face. Even if the face is
* scalable, there might still be bitmap strikes, which are called
* 'sbits' in that case.
*
* available_sizes ::
* An array of @FT_Bitmap_Size for all bitmap strikes in the face. It
* is set to `NULL` if there is no bitmap strike.
*
* Note that FreeType tries to sanitize the strike data since they are
* sometimes sloppy or incorrect, but this can easily fail.
*
* num_charmaps ::
* The number of charmaps in the face.
*
* charmaps ::
* An array of the charmaps of the face.
*
* generic ::
* A field reserved for client uses. See the @FT_Generic type
* description.
*
* bbox ::
* The font bounding box. Coordinates are expressed in font units (see
* `units_per_EM`). The box is large enough to contain any glyph from
* the font. Thus, `bbox.yMax` can be seen as the 'maximum ascender',
* and `bbox.yMin` as the 'minimum descender'. Only relevant for
* scalable formats.
*
* Note that the bounding box might be off by (at least) one pixel for
* hinted fonts. See @FT_Size_Metrics for further discussion.
*
* Note that the bounding box does not vary in OpenType variable fonts
* and should only be used in relation to the default instance.
*
* units_per_EM ::
* The number of font units per EM square for this face. This is
* typically 2048 for TrueType fonts, and 1000 for Type~1 fonts. Only
* relevant for scalable formats.
*
* ascender ::
* The typographic ascender of the face, expressed in font units. For
* font formats not having this information, it is set to `bbox.yMax`.
* Only relevant for scalable formats.
*
* descender ::
* The typographic descender of the face, expressed in font units. For
* font formats not having this information, it is set to `bbox.yMin`.
* Note that this field is negative for values below the baseline.
* Only relevant for scalable formats.
*
* height ::
* This value is the vertical distance between two consecutive
* baselines, expressed in font units. It is always positive. Only
* relevant for scalable formats.
*
* If you want the global glyph height, use `ascender - descender`.
*
* max_advance_width ::
* The maximum advance width, in font units, for all glyphs in this
* face. This can be used to make word wrapping computations faster.
* Only relevant for scalable formats.
*
* max_advance_height ::
* The maximum advance height, in font units, for all glyphs in this
* face. This is only relevant for vertical layouts, and is set to
* `height` for fonts that do not provide vertical metrics. Only
* relevant for scalable formats.
*
* underline_position ::
* The position, in font units, of the underline line for this face.
* It is the center of the underlining stem. Only relevant for
* scalable formats.
*
* underline_thickness ::
* The thickness, in font units, of the underline for this face. Only
* relevant for scalable formats.
*
* glyph ::
* The face's associated glyph slot(s).
*
* size ::
* The current active size for this face.
*
* charmap ::
* The current active charmap for this face.
*
* @note:
* Fields may be changed after a call to @FT_Attach_File or
* @FT_Attach_Stream.
*
* For an OpenType variation font, the values of the following fields can
* change after a call to @FT_Set_Var_Design_Coordinates (and friends) if
* the font contains an 'MVAR' table: `ascender`, `descender`, `height`,
* `underline_position`, and `underline_thickness`.
*
* Especially for TrueType fonts see also the documentation for
* @FT_Size_Metrics.
*/
typedef struct FT_FaceRec_
{
FT_Long num_faces;
FT_Long face_index;
FT_Long face_flags;
FT_Long style_flags;
FT_Long num_glyphs;
FT_String* family_name;
FT_String* style_name;
FT_Int num_fixed_sizes;
FT_Bitmap_Size* available_sizes;
FT_Int num_charmaps;
FT_CharMap* charmaps;
FT_Generic generic;
/*# The following member variables (down to `underline_thickness`) */
/*# are only relevant to scalable outlines; cf. @FT_Bitmap_Size */
/*# for bitmap fonts. */
FT_BBox bbox;
FT_UShort units_per_EM;
FT_Short ascender;
FT_Short descender;
FT_Short height;
FT_Short max_advance_width;
FT_Short max_advance_height;
FT_Short underline_position;
FT_Short underline_thickness;
FT_GlyphSlot glyph;
FT_Size size;
FT_CharMap charmap;
/*@private begin */
FT_Driver driver;
FT_Memory memory;
FT_Stream stream;
FT_ListRec sizes_list;
FT_Generic autohint; /* face-specific auto-hinter data */
void* extensions; /* unused */
FT_Face_Internal internal;
/*@private end */
} FT_FaceRec;
/**************************************************************************
*
* @enum:
* FT_FACE_FLAG_XXX
*
* @description:
* A list of bit flags used in the `face_flags` field of the @FT_FaceRec
* structure. They inform client applications of properties of the
* corresponding face.
*
* @values:
* FT_FACE_FLAG_SCALABLE ::
* The face contains outline glyphs. Note that a face can contain
* bitmap strikes also, i.e., a face can have both this flag and
* @FT_FACE_FLAG_FIXED_SIZES set.
*
* FT_FACE_FLAG_FIXED_SIZES ::
* The face contains bitmap strikes. See also the `num_fixed_sizes`
* and `available_sizes` fields of @FT_FaceRec.
*
* FT_FACE_FLAG_FIXED_WIDTH ::
* The face contains fixed-width characters (like Courier, Lucida,
* MonoType, etc.).
*
* FT_FACE_FLAG_SFNT ::
* The face uses the SFNT storage scheme. For now, this means TrueType
* and OpenType.
*
* FT_FACE_FLAG_HORIZONTAL ::
* The face contains horizontal glyph metrics. This should be set for
* all common formats.
*
* FT_FACE_FLAG_VERTICAL ::
* The face contains vertical glyph metrics. This is only available in
* some formats, not all of them.
*
* FT_FACE_FLAG_KERNING ::
* The face contains kerning information. If set, the kerning distance
* can be retrieved using the function @FT_Get_Kerning. Otherwise the
* function always return the vector (0,0). Note that FreeType doesn't
* handle kerning data from the SFNT 'GPOS' table (as present in many
* OpenType fonts).
*
* FT_FACE_FLAG_FAST_GLYPHS ::
* THIS FLAG IS DEPRECATED. DO NOT USE OR TEST IT.
*
* FT_FACE_FLAG_MULTIPLE_MASTERS ::
* The face contains multiple masters and is capable of interpolating
* between them. Supported formats are Adobe MM, TrueType GX, and
* OpenType variation fonts.
*
* See section @multiple_masters for API details.
*
* FT_FACE_FLAG_GLYPH_NAMES ::
* The face contains glyph names, which can be retrieved using
* @FT_Get_Glyph_Name. Note that some TrueType fonts contain broken
* glyph name tables. Use the function @FT_Has_PS_Glyph_Names when
* needed.
*
* FT_FACE_FLAG_EXTERNAL_STREAM ::
* Used internally by FreeType to indicate that a face's stream was
* provided by the client application and should not be destroyed when
* @FT_Done_Face is called. Don't read or test this flag.
*
* FT_FACE_FLAG_HINTER ::
* The font driver has a hinting machine of its own. For example, with
* TrueType fonts, it makes sense to use data from the SFNT 'gasp'
* table only if the native TrueType hinting engine (with the bytecode
* interpreter) is available and active.
*
* FT_FACE_FLAG_CID_KEYED ::
* The face is CID-keyed. In that case, the face is not accessed by
* glyph indices but by CID values. For subsetted CID-keyed fonts this
* has the consequence that not all index values are a valid argument
* to @FT_Load_Glyph. Only the CID values for which corresponding
* glyphs in the subsetted font exist make `FT_Load_Glyph` return
* successfully; in all other cases you get an
* `FT_Err_Invalid_Argument` error.
*
* Note that CID-keyed fonts that are in an SFNT wrapper (this is, all
* OpenType/CFF fonts) don't have this flag set since the glyphs are
* accessed in the normal way (using contiguous indices); the
* 'CID-ness' isn't visible to the application.
*
* FT_FACE_FLAG_TRICKY ::
* The face is 'tricky', this is, it always needs the font format's
* native hinting engine to get a reasonable result. A typical example
* is the old Chinese font `mingli.ttf` (but not `mingliu.ttc`) that
* uses TrueType bytecode instructions to move and scale all of its
* subglyphs.
*
* It is not possible to auto-hint such fonts using
* @FT_LOAD_FORCE_AUTOHINT; it will also ignore @FT_LOAD_NO_HINTING.
* You have to set both @FT_LOAD_NO_HINTING and @FT_LOAD_NO_AUTOHINT to
* really disable hinting; however, you probably never want this except
* for demonstration purposes.
*
* Currently, there are about a dozen TrueType fonts in the list of
* tricky fonts; they are hard-coded in file `ttobjs.c`.
*
* FT_FACE_FLAG_COLOR ::
* [Since 2.5.1] The face has color glyph tables. See @FT_LOAD_COLOR
* for more information.
*
* FT_FACE_FLAG_VARIATION ::
* [Since 2.9] Set if the current face (or named instance) has been
* altered with @FT_Set_MM_Design_Coordinates,
* @FT_Set_Var_Design_Coordinates, or @FT_Set_Var_Blend_Coordinates.
* This flag is unset by a call to @FT_Set_Named_Instance.
*/
#define FT_FACE_FLAG_SCALABLE ( 1L << 0 )
#define FT_FACE_FLAG_FIXED_SIZES ( 1L << 1 )
#define FT_FACE_FLAG_FIXED_WIDTH ( 1L << 2 )
#define FT_FACE_FLAG_SFNT ( 1L << 3 )
#define FT_FACE_FLAG_HORIZONTAL ( 1L << 4 )
#define FT_FACE_FLAG_VERTICAL ( 1L << 5 )
#define FT_FACE_FLAG_KERNING ( 1L << 6 )
#define FT_FACE_FLAG_FAST_GLYPHS ( 1L << 7 )
#define FT_FACE_FLAG_MULTIPLE_MASTERS ( 1L << 8 )
#define FT_FACE_FLAG_GLYPH_NAMES ( 1L << 9 )
#define FT_FACE_FLAG_EXTERNAL_STREAM ( 1L << 10 )
#define FT_FACE_FLAG_HINTER ( 1L << 11 )
#define FT_FACE_FLAG_CID_KEYED ( 1L << 12 )
#define FT_FACE_FLAG_TRICKY ( 1L << 13 )
#define FT_FACE_FLAG_COLOR ( 1L << 14 )
#define FT_FACE_FLAG_VARIATION ( 1L << 15 )
/**************************************************************************
*
* @macro:
* FT_HAS_HORIZONTAL
*
* @description:
* A macro that returns true whenever a face object contains horizontal
* metrics (this is true for all font formats though).
*
* @also:
* @FT_HAS_VERTICAL can be used to check for vertical metrics.
*
*/
#define FT_HAS_HORIZONTAL( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_HORIZONTAL ) )
/**************************************************************************
*
* @macro:
* FT_HAS_VERTICAL
*
* @description:
* A macro that returns true whenever a face object contains real
* vertical metrics (and not only synthesized ones).
*
*/
#define FT_HAS_VERTICAL( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_VERTICAL ) )
/**************************************************************************
*
* @macro:
* FT_HAS_KERNING
*
* @description:
* A macro that returns true whenever a face object contains kerning data
* that can be accessed with @FT_Get_Kerning.
*
*/
#define FT_HAS_KERNING( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_KERNING ) )
/**************************************************************************
*
* @macro:
* FT_IS_SCALABLE
*
* @description:
* A macro that returns true whenever a face object contains a scalable
* font face (true for TrueType, Type~1, Type~42, CID, OpenType/CFF, and
* PFR font formats).
*
*/
#define FT_IS_SCALABLE( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_SCALABLE ) )
/**************************************************************************
*
* @macro:
* FT_IS_SFNT
*
* @description:
* A macro that returns true whenever a face object contains a font whose
* format is based on the SFNT storage scheme. This usually means:
* TrueType fonts, OpenType fonts, as well as SFNT-based embedded bitmap
* fonts.
*
* If this macro is true, all functions defined in @FT_SFNT_NAMES_H and
* @FT_TRUETYPE_TABLES_H are available.
*
*/
#define FT_IS_SFNT( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_SFNT ) )
/**************************************************************************
*
* @macro:
* FT_IS_FIXED_WIDTH
*
* @description:
* A macro that returns true whenever a face object contains a font face
* that contains fixed-width (or 'monospace', 'fixed-pitch', etc.)
* glyphs.
*
*/
#define FT_IS_FIXED_WIDTH( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_FIXED_WIDTH ) )
/**************************************************************************
*
* @macro:
* FT_HAS_FIXED_SIZES
*
* @description:
* A macro that returns true whenever a face object contains some
* embedded bitmaps. See the `available_sizes` field of the @FT_FaceRec
* structure.
*
*/
#define FT_HAS_FIXED_SIZES( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_FIXED_SIZES ) )
/**************************************************************************
*
* @macro:
* FT_HAS_FAST_GLYPHS
*
* @description:
* Deprecated.
*
*/
#define FT_HAS_FAST_GLYPHS( face ) 0
/**************************************************************************
*
* @macro:
* FT_HAS_GLYPH_NAMES
*
* @description:
* A macro that returns true whenever a face object contains some glyph
* names that can be accessed through @FT_Get_Glyph_Name.
*
*/
#define FT_HAS_GLYPH_NAMES( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_GLYPH_NAMES ) )
/**************************************************************************
*
* @macro:
* FT_HAS_MULTIPLE_MASTERS
*
* @description:
* A macro that returns true whenever a face object contains some
* multiple masters. The functions provided by @FT_MULTIPLE_MASTERS_H
* are then available to choose the exact design you want.
*
*/
#define FT_HAS_MULTIPLE_MASTERS( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_MULTIPLE_MASTERS ) )
/**************************************************************************
*
* @macro:
* FT_IS_NAMED_INSTANCE
*
* @description:
* A macro that returns true whenever a face object is a named instance
* of a GX or OpenType variation font.
*
* [Since 2.9] Changing the design coordinates with
* @FT_Set_Var_Design_Coordinates or @FT_Set_Var_Blend_Coordinates does
* not influence the return value of this macro (only
* @FT_Set_Named_Instance does that).
*
* @since:
* 2.7
*
*/
#define FT_IS_NAMED_INSTANCE( face ) \
( !!( (face)->face_index & 0x7FFF0000L ) )
/**************************************************************************
*
* @macro:
* FT_IS_VARIATION
*
* @description:
* A macro that returns true whenever a face object has been altered by
* @FT_Set_MM_Design_Coordinates, @FT_Set_Var_Design_Coordinates, or
* @FT_Set_Var_Blend_Coordinates.
*
* @since:
* 2.9
*
*/
#define FT_IS_VARIATION( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_VARIATION ) )
/**************************************************************************
*
* @macro:
* FT_IS_CID_KEYED
*
* @description:
* A macro that returns true whenever a face object contains a CID-keyed
* font. See the discussion of @FT_FACE_FLAG_CID_KEYED for more details.
*
* If this macro is true, all functions defined in @FT_CID_H are
* available.
*
*/
#define FT_IS_CID_KEYED( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_CID_KEYED ) )
/**************************************************************************
*
* @macro:
* FT_IS_TRICKY
*
* @description:
* A macro that returns true whenever a face represents a 'tricky' font.
* See the discussion of @FT_FACE_FLAG_TRICKY for more details.
*
*/
#define FT_IS_TRICKY( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_TRICKY ) )
/**************************************************************************
*
* @macro:
* FT_HAS_COLOR
*
* @description:
* A macro that returns true whenever a face object contains tables for
* color glyphs.
*
* @since:
* 2.5.1
*
*/
#define FT_HAS_COLOR( face ) \
( !!( (face)->face_flags & FT_FACE_FLAG_COLOR ) )
/**************************************************************************
*
* @enum:
* FT_STYLE_FLAG_XXX
*
* @description:
* A list of bit flags to indicate the style of a given face. These are
* used in the `style_flags` field of @FT_FaceRec.
*
* @values:
* FT_STYLE_FLAG_ITALIC ::
* The face style is italic or oblique.
*
* FT_STYLE_FLAG_BOLD ::
* The face is bold.
*
* @note:
* The style information as provided by FreeType is very basic. More
* details are beyond the scope and should be done on a higher level (for
* example, by analyzing various fields of the 'OS/2' table in SFNT based
* fonts).
*/
#define FT_STYLE_FLAG_ITALIC ( 1 << 0 )
#define FT_STYLE_FLAG_BOLD ( 1 << 1 )
/**************************************************************************
*
* @type:
* FT_Size_Internal
*
* @description:
* An opaque handle to an `FT_Size_InternalRec` structure, used to model
* private data of a given @FT_Size object.
*/
typedef struct FT_Size_InternalRec_* FT_Size_Internal;
/**************************************************************************
*
* @struct:
* FT_Size_Metrics
*
* @description:
* The size metrics structure gives the metrics of a size object.
*
* @fields:
* x_ppem ::
* The width of the scaled EM square in pixels, hence the term 'ppem'
* (pixels per EM). It is also referred to as 'nominal width'.
*
* y_ppem ::
* The height of the scaled EM square in pixels, hence the term 'ppem'
* (pixels per EM). It is also referred to as 'nominal height'.
*
* x_scale ::
* A 16.16 fractional scaling value to convert horizontal metrics from
* font units to 26.6 fractional pixels. Only relevant for scalable
* font formats.
*
* y_scale ::
* A 16.16 fractional scaling value to convert vertical metrics from
* font units to 26.6 fractional pixels. Only relevant for scalable
* font formats.
*
* ascender ::
* The ascender in 26.6 fractional pixels, rounded up to an integer
* value. See @FT_FaceRec for the details.
*
* descender ::
* The descender in 26.6 fractional pixels, rounded down to an integer
* value. See @FT_FaceRec for the details.
*
* height ::
* The height in 26.6 fractional pixels, rounded to an integer value.
* See @FT_FaceRec for the details.
*
* max_advance ::
* The maximum advance width in 26.6 fractional pixels, rounded to an
* integer value. See @FT_FaceRec for the details.
*
* @note:
* The scaling values, if relevant, are determined first during a size
* changing operation. The remaining fields are then set by the driver.
* For scalable formats, they are usually set to scaled values of the
* corresponding fields in @FT_FaceRec. Some values like ascender or
* descender are rounded for historical reasons; more precise values (for
* outline fonts) can be derived by scaling the corresponding @FT_FaceRec
* values manually, with code similar to the following.
*
* ```
* scaled_ascender = FT_MulFix( face->ascender,
* size_metrics->y_scale );
* ```
*
* Note that due to glyph hinting and the selected rendering mode these
* values are usually not exact; consequently, they must be treated as
* unreliable with an error margin of at least one pixel!
*
* Indeed, the only way to get the exact metrics is to render _all_
* glyphs. As this would be a definite performance hit, it is up to
* client applications to perform such computations.
*
* The `FT_Size_Metrics` structure is valid for bitmap fonts also.
*
*
* **TrueType fonts with native bytecode hinting**
*
* All applications that handle TrueType fonts with native hinting must
* be aware that TTFs expect different rounding of vertical font
* dimensions. The application has to cater for this, especially if it
* wants to rely on a TTF's vertical data (for example, to properly align
* box characters vertically).
*
* Only the application knows _in advance_ that it is going to use native
* hinting for TTFs! FreeType, on the other hand, selects the hinting
* mode not at the time of creating an @FT_Size object but much later,
* namely while calling @FT_Load_Glyph.
*
* Here is some pseudo code that illustrates a possible solution.
*
* ```
* font_format = FT_Get_Font_Format( face );
*
* if ( !strcmp( font_format, "TrueType" ) &&
* do_native_bytecode_hinting )
* {
* ascender = ROUND( FT_MulFix( face->ascender,
* size_metrics->y_scale ) );
* descender = ROUND( FT_MulFix( face->descender,
* size_metrics->y_scale ) );
* }
* else
* {
* ascender = size_metrics->ascender;
* descender = size_metrics->descender;
* }
*
* height = size_metrics->height;
* max_advance = size_metrics->max_advance;
* ```
*/
typedef struct FT_Size_Metrics_
{
FT_UShort x_ppem; /* horizontal pixels per EM */
FT_UShort y_ppem; /* vertical pixels per EM */
FT_Fixed x_scale; /* scaling values used to convert font */
FT_Fixed y_scale; /* units to 26.6 fractional pixels */
FT_Pos ascender; /* ascender in 26.6 frac. pixels */
FT_Pos descender; /* descender in 26.6 frac. pixels */
FT_Pos height; /* text height in 26.6 frac. pixels */
FT_Pos max_advance; /* max horizontal advance, in 26.6 pixels */
} FT_Size_Metrics;
/**************************************************************************
*
* @struct:
* FT_SizeRec
*
* @description:
* FreeType root size class structure. A size object models a face
* object at a given size.
*
* @fields:
* face ::
* Handle to the parent face object.
*
* generic ::
* A typeless pointer, unused by the FreeType library or any of its
* drivers. It can be used by client applications to link their own
* data to each size object.
*
* metrics ::
* Metrics for this size object. This field is read-only.
*/
typedef struct FT_SizeRec_
{
FT_Face face; /* parent face object */
FT_Generic generic; /* generic pointer for client uses */
FT_Size_Metrics metrics; /* size metrics */
FT_Size_Internal internal;
} FT_SizeRec;
/**************************************************************************
*
* @struct:
* FT_SubGlyph
*
* @description:
* The subglyph structure is an internal object used to describe
* subglyphs (for example, in the case of composites).
*
* @note:
* The subglyph implementation is not part of the high-level API, hence
* the forward structure declaration.
*
* You can however retrieve subglyph information with
* @FT_Get_SubGlyph_Info.
*/
typedef struct FT_SubGlyphRec_* FT_SubGlyph;
/**************************************************************************
*
* @type:
* FT_Slot_Internal
*
* @description:
* An opaque handle to an `FT_Slot_InternalRec` structure, used to model
* private data of a given @FT_GlyphSlot object.
*/
typedef struct FT_Slot_InternalRec_* FT_Slot_Internal;
/**************************************************************************
*
* @struct:
* FT_GlyphSlotRec
*
* @description:
* FreeType root glyph slot class structure. A glyph slot is a container
* where individual glyphs can be loaded, be they in outline or bitmap
* format.
*
* @fields:
* library ::
* A handle to the FreeType library instance this slot belongs to.
*
* face ::
* A handle to the parent face object.
*
* next ::
* In some cases (like some font tools), several glyph slots per face
* object can be a good thing. As this is rare, the glyph slots are
* listed through a direct, single-linked list using its `next` field.
*
* glyph_index ::
* [Since 2.10] The glyph index passed as an argument to @FT_Load_Glyph
* while initializing the glyph slot.
*
* generic ::
* A typeless pointer unused by the FreeType library or any of its
* drivers. It can be used by client applications to link their own
* data to each glyph slot object.
*
* metrics ::
* The metrics of the last loaded glyph in the slot. The returned
* values depend on the last load flags (see the @FT_Load_Glyph API
* function) and can be expressed either in 26.6 fractional pixels or
* font units.
*
* Note that even when the glyph image is transformed, the metrics are
* not.
*
* linearHoriAdvance ::
* The advance width of the unhinted glyph. Its value is expressed in
* 16.16 fractional pixels, unless @FT_LOAD_LINEAR_DESIGN is set when
* loading the glyph. This field can be important to perform correct
* WYSIWYG layout. Only relevant for outline glyphs.
*
* linearVertAdvance ::
* The advance height of the unhinted glyph. Its value is expressed in
* 16.16 fractional pixels, unless @FT_LOAD_LINEAR_DESIGN is set when
* loading the glyph. This field can be important to perform correct
* WYSIWYG layout. Only relevant for outline glyphs.
*
* advance ::
* This shorthand is, depending on @FT_LOAD_IGNORE_TRANSFORM, the
* transformed (hinted) advance width for the glyph, in 26.6 fractional
* pixel format. As specified with @FT_LOAD_VERTICAL_LAYOUT, it uses
* either the `horiAdvance` or the `vertAdvance` value of `metrics`
* field.
*
* format ::
* This field indicates the format of the image contained in the glyph
* slot. Typically @FT_GLYPH_FORMAT_BITMAP, @FT_GLYPH_FORMAT_OUTLINE,
* or @FT_GLYPH_FORMAT_COMPOSITE, but other values are possible.
*
* bitmap ::
* This field is used as a bitmap descriptor. Note that the address
* and content of the bitmap buffer can change between calls of
* @FT_Load_Glyph and a few other functions.
*
* bitmap_left ::
* The bitmap's left bearing expressed in integer pixels.
*
* bitmap_top ::
* The bitmap's top bearing expressed in integer pixels. This is the
* distance from the baseline to the top-most glyph scanline, upwards
* y~coordinates being **positive**.
*
* outline ::
* The outline descriptor for the current glyph image if its format is
* @FT_GLYPH_FORMAT_OUTLINE. Once a glyph is loaded, `outline` can be
* transformed, distorted, emboldened, etc. However, it must not be
* freed.
*
* [Since 2.10.1] If @FT_LOAD_NO_SCALE is set, outline coordinates of
* OpenType variation fonts for a selected instance are internally
* handled as 26.6 fractional font units but returned as (rounded)
* integers, as expected. To get unrounded font units, don't use
* @FT_LOAD_NO_SCALE but load the glyph with @FT_LOAD_NO_HINTING and
* scale it, using the font's `units_per_EM` value as the ppem.
*
* num_subglyphs ::
* The number of subglyphs in a composite glyph. This field is only
* valid for the composite glyph format that should normally only be
* loaded with the @FT_LOAD_NO_RECURSE flag.
*
* subglyphs ::
* An array of subglyph descriptors for composite glyphs. There are
* `num_subglyphs` elements in there. Currently internal to FreeType.
*
* control_data ::
* Certain font drivers can also return the control data for a given
* glyph image (e.g. TrueType bytecode, Type~1 charstrings, etc.).
* This field is a pointer to such data; it is currently internal to
* FreeType.
*
* control_len ::
* This is the length in bytes of the control data. Currently internal
* to FreeType.
*
* other ::
* Reserved.
*
* lsb_delta ::
* The difference between hinted and unhinted left side bearing while
* auto-hinting is active. Zero otherwise.
*
* rsb_delta ::
* The difference between hinted and unhinted right side bearing while
* auto-hinting is active. Zero otherwise.
*
* @note:
* If @FT_Load_Glyph is called with default flags (see @FT_LOAD_DEFAULT)
* the glyph image is loaded in the glyph slot in its native format
* (e.g., an outline glyph for TrueType and Type~1 formats). [Since 2.9]
* The prospective bitmap metrics are calculated according to
* @FT_LOAD_TARGET_XXX and other flags even for the outline glyph, even
* if @FT_LOAD_RENDER is not set.
*
* This image can later be converted into a bitmap by calling
* @FT_Render_Glyph. This function searches the current renderer for the
* native image's format, then invokes it.
*
* The renderer is in charge of transforming the native image through the
* slot's face transformation fields, then converting it into a bitmap
* that is returned in `slot->bitmap`.
*
* Note that `slot->bitmap_left` and `slot->bitmap_top` are also used to
* specify the position of the bitmap relative to the current pen
* position (e.g., coordinates (0,0) on the baseline). Of course,
* `slot->format` is also changed to @FT_GLYPH_FORMAT_BITMAP.
*
* Here is a small pseudo code fragment that shows how to use `lsb_delta`
* and `rsb_delta` to do fractional positioning of glyphs:
*
* ```
* FT_GlyphSlot slot = face->glyph;
* FT_Pos origin_x = 0;
*
*
* for all glyphs do
* <load glyph with `FT_Load_Glyph'>
*
* FT_Outline_Translate( slot->outline, origin_x & 63, 0 );
*
* <save glyph image, or render glyph, or ...>
*
* <compute kern between current and next glyph
* and add it to `origin_x'>
*
* origin_x += slot->advance.x;
* origin_x += slot->lsb_delta - slot->rsb_delta;
* endfor
* ```
*
* Here is another small pseudo code fragment that shows how to use
* `lsb_delta` and `rsb_delta` to improve integer positioning of glyphs:
*
* ```
* FT_GlyphSlot slot = face->glyph;
* FT_Pos origin_x = 0;
* FT_Pos prev_rsb_delta = 0;
*
*
* for all glyphs do
* <compute kern between current and previous glyph
* and add it to `origin_x'>
*
* <load glyph with `FT_Load_Glyph'>
*
* if ( prev_rsb_delta - slot->lsb_delta > 32 )
* origin_x -= 64;
* else if ( prev_rsb_delta - slot->lsb_delta < -31 )
* origin_x += 64;
*
* prev_rsb_delta = slot->rsb_delta;
*
* <save glyph image, or render glyph, or ...>
*
* origin_x += slot->advance.x;
* endfor
* ```
*
* If you use strong auto-hinting, you **must** apply these delta values!
* Otherwise you will experience far too large inter-glyph spacing at
* small rendering sizes in most cases. Note that it doesn't harm to use
* the above code for other hinting modes also, since the delta values
* are zero then.
*/
typedef struct FT_GlyphSlotRec_
{
FT_Library library;
FT_Face face;
FT_GlyphSlot next;
FT_UInt glyph_index; /* new in 2.10; was reserved previously */
FT_Generic generic;
FT_Glyph_Metrics metrics;
FT_Fixed linearHoriAdvance;
FT_Fixed linearVertAdvance;
FT_Vector advance;
FT_Glyph_Format format;
FT_Bitmap bitmap;
FT_Int bitmap_left;
FT_Int bitmap_top;
FT_Outline outline;
FT_UInt num_subglyphs;
FT_SubGlyph subglyphs;
void* control_data;
long control_len;
FT_Pos lsb_delta;
FT_Pos rsb_delta;
void* other;
FT_Slot_Internal internal;
} FT_GlyphSlotRec;
/*************************************************************************/
/*************************************************************************/
/* */
/* F U N C T I O N S */
/* */
/*************************************************************************/
/*************************************************************************/
/**************************************************************************
*
* @function:
* FT_Init_FreeType
*
* @description:
* Initialize a new FreeType library object. The set of modules that are
* registered by this function is determined at build time.
*
* @output:
* alibrary ::
* A handle to a new library object.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* In case you want to provide your own memory allocating routines, use
* @FT_New_Library instead, followed by a call to @FT_Add_Default_Modules
* (or a series of calls to @FT_Add_Module) and
* @FT_Set_Default_Properties.
*
* See the documentation of @FT_Library and @FT_Face for multi-threading
* issues.
*
* If you need reference-counting (cf. @FT_Reference_Library), use
* @FT_New_Library and @FT_Done_Library.
*
* If compilation option `FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES` is
* set, this function reads the `FREETYPE_PROPERTIES` environment
* variable to control driver properties. See section @properties for
* more.
*/
FT_EXPORT( FT_Error )
FT_Init_FreeType( FT_Library *alibrary );
/**************************************************************************
*
* @function:
* FT_Done_FreeType
*
* @description:
* Destroy a given FreeType library object and all of its children,
* including resources, drivers, faces, sizes, etc.
*
* @input:
* library ::
* A handle to the target library object.
*
* @return:
* FreeType error code. 0~means success.
*/
FT_EXPORT( FT_Error )
FT_Done_FreeType( FT_Library library );
/**************************************************************************
*
* @enum:
* FT_OPEN_XXX
*
* @description:
* A list of bit field constants used within the `flags` field of the
* @FT_Open_Args structure.
*
* @values:
* FT_OPEN_MEMORY ::
* This is a memory-based stream.
*
* FT_OPEN_STREAM ::
* Copy the stream from the `stream` field.
*
* FT_OPEN_PATHNAME ::
* Create a new input stream from a C~path name.
*
* FT_OPEN_DRIVER ::
* Use the `driver` field.
*
* FT_OPEN_PARAMS ::
* Use the `num_params` and `params` fields.
*
* @note:
* The `FT_OPEN_MEMORY`, `FT_OPEN_STREAM`, and `FT_OPEN_PATHNAME` flags
* are mutually exclusive.
*/
#define FT_OPEN_MEMORY 0x1
#define FT_OPEN_STREAM 0x2
#define FT_OPEN_PATHNAME 0x4
#define FT_OPEN_DRIVER 0x8
#define FT_OPEN_PARAMS 0x10
/* these constants are deprecated; use the corresponding `FT_OPEN_XXX` */
/* values instead */
#define ft_open_memory FT_OPEN_MEMORY
#define ft_open_stream FT_OPEN_STREAM
#define ft_open_pathname FT_OPEN_PATHNAME
#define ft_open_driver FT_OPEN_DRIVER
#define ft_open_params FT_OPEN_PARAMS
/**************************************************************************
*
* @struct:
* FT_Parameter
*
* @description:
* A simple structure to pass more or less generic parameters to
* @FT_Open_Face and @FT_Face_Properties.
*
* @fields:
* tag ::
* A four-byte identification tag.
*
* data ::
* A pointer to the parameter data.
*
* @note:
* The ID and function of parameters are driver-specific. See section
* @parameter_tags for more information.
*/
typedef struct FT_Parameter_
{
FT_ULong tag;
FT_Pointer data;
} FT_Parameter;
/**************************************************************************
*
* @struct:
* FT_Open_Args
*
* @description:
* A structure to indicate how to open a new font file or stream. A
* pointer to such a structure can be used as a parameter for the
* functions @FT_Open_Face and @FT_Attach_Stream.
*
* @fields:
* flags ::
* A set of bit flags indicating how to use the structure.
*
* memory_base ::
* The first byte of the file in memory.
*
* memory_size ::
* The size in bytes of the file in memory.
*
* pathname ::
* A pointer to an 8-bit file pathname. The pointer is not owned by
* FreeType.
*
* stream ::
* A handle to a source stream object.
*
* driver ::
* This field is exclusively used by @FT_Open_Face; it simply specifies
* the font driver to use for opening the face. If set to `NULL`,
* FreeType tries to load the face with each one of the drivers in its
* list.
*
* num_params ::
* The number of extra parameters.
*
* params ::
* Extra parameters passed to the font driver when opening a new face.
*
* @note:
* The stream type is determined by the contents of `flags` that are
* tested in the following order by @FT_Open_Face:
*
* If the @FT_OPEN_MEMORY bit is set, assume that this is a memory file
* of `memory_size` bytes, located at `memory_address`. The data are not
* copied, and the client is responsible for releasing and destroying
* them _after_ the corresponding call to @FT_Done_Face.
*
* Otherwise, if the @FT_OPEN_STREAM bit is set, assume that a custom
* input stream `stream` is used.
*
* Otherwise, if the @FT_OPEN_PATHNAME bit is set, assume that this is a
* normal file and use `pathname` to open it.
*
* If the @FT_OPEN_DRIVER bit is set, @FT_Open_Face only tries to open
* the file with the driver whose handler is in `driver`.
*
* If the @FT_OPEN_PARAMS bit is set, the parameters given by
* `num_params` and `params` is used. They are ignored otherwise.
*
* Ideally, both the `pathname` and `params` fields should be tagged as
* 'const'; this is missing for API backward compatibility. In other
* words, applications should treat them as read-only.
*/
typedef struct FT_Open_Args_
{
FT_UInt flags;
const FT_Byte* memory_base;
FT_Long memory_size;
FT_String* pathname;
FT_Stream stream;
FT_Module driver;
FT_Int num_params;
FT_Parameter* params;
} FT_Open_Args;
/**************************************************************************
*
* @function:
* FT_New_Face
*
* @description:
* Call @FT_Open_Face to open a font by its pathname.
*
* @inout:
* library ::
* A handle to the library resource.
*
* @input:
* pathname ::
* A path to the font file.
*
* face_index ::
* See @FT_Open_Face for a detailed description of this parameter.
*
* @output:
* aface ::
* A handle to a new face object. If `face_index` is greater than or
* equal to zero, it must be non-`NULL`.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Use @FT_Done_Face to destroy the created @FT_Face object (along with
* its slot and sizes).
*/
FT_EXPORT( FT_Error )
FT_New_Face( FT_Library library,
const char* filepathname,
FT_Long face_index,
FT_Face *aface );
/**************************************************************************
*
* @function:
* FT_New_Memory_Face
*
* @description:
* Call @FT_Open_Face to open a font that has been loaded into memory.
*
* @inout:
* library ::
* A handle to the library resource.
*
* @input:
* file_base ::
* A pointer to the beginning of the font data.
*
* file_size ::
* The size of the memory chunk used by the font data.
*
* face_index ::
* See @FT_Open_Face for a detailed description of this parameter.
*
* @output:
* aface ::
* A handle to a new face object. If `face_index` is greater than or
* equal to zero, it must be non-`NULL`.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* You must not deallocate the memory before calling @FT_Done_Face.
*/
FT_EXPORT( FT_Error )
FT_New_Memory_Face( FT_Library library,
const FT_Byte* file_base,
FT_Long file_size,
FT_Long face_index,
FT_Face *aface );
/**************************************************************************
*
* @function:
* FT_Open_Face
*
* @description:
* Create a face object from a given resource described by @FT_Open_Args.
*
* @inout:
* library ::
* A handle to the library resource.
*
* @input:
* args ::
* A pointer to an `FT_Open_Args` structure that must be filled by the
* caller.
*
* face_index ::
* This field holds two different values. Bits 0-15 are the index of
* the face in the font file (starting with value~0). Set it to~0 if
* there is only one face in the font file.
*
* [Since 2.6.1] Bits 16-30 are relevant to GX and OpenType variation
* fonts only, specifying the named instance index for the current face
* index (starting with value~1; value~0 makes FreeType ignore named
* instances). For non-variation fonts, bits 16-30 are ignored.
* Assuming that you want to access the third named instance in face~4,
* `face_index` should be set to 0x00030004. If you want to access
* face~4 without variation handling, simply set `face_index` to
* value~4.
*
* `FT_Open_Face` and its siblings can be used to quickly check whether
* the font format of a given font resource is supported by FreeType.
* In general, if the `face_index` argument is negative, the function's
* return value is~0 if the font format is recognized, or non-zero
* otherwise. The function allocates a more or less empty face handle
* in `*aface` (if `aface` isn't `NULL`); the only two useful fields in
* this special case are `face->num_faces` and `face->style_flags`.
* For any negative value of `face_index`, `face->num_faces` gives the
* number of faces within the font file. For the negative value
* '-(N+1)' (with 'N' a non-negative 16-bit value), bits 16-30 in
* `face->style_flags` give the number of named instances in face 'N'
* if we have a variation font (or zero otherwise). After examination,
* the returned @FT_Face structure should be deallocated with a call to
* @FT_Done_Face.
*
* @output:
* aface ::
* A handle to a new face object. If `face_index` is greater than or
* equal to zero, it must be non-`NULL`.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Unlike FreeType 1.x, this function automatically creates a glyph slot
* for the face object that can be accessed directly through
* `face->glyph`.
*
* Each new face object created with this function also owns a default
* @FT_Size object, accessible as `face->size`.
*
* One @FT_Library instance can have multiple face objects, this is,
* @FT_Open_Face and its siblings can be called multiple times using the
* same `library` argument.
*
* See the discussion of reference counters in the description of
* @FT_Reference_Face.
*
* @example:
* To loop over all faces, use code similar to the following snippet
* (omitting the error handling).
*
* ```
* ...
* FT_Face face;
* FT_Long i, num_faces;
*
*
* error = FT_Open_Face( library, args, -1, &face );
* if ( error ) { ... }
*
* num_faces = face->num_faces;
* FT_Done_Face( face );
*
* for ( i = 0; i < num_faces; i++ )
* {
* ...
* error = FT_Open_Face( library, args, i, &face );
* ...
* FT_Done_Face( face );
* ...
* }
* ```
*
* To loop over all valid values for `face_index`, use something similar
* to the following snippet, again without error handling. The code
* accesses all faces immediately (thus only a single call of
* `FT_Open_Face` within the do-loop), with and without named instances.
*
* ```
* ...
* FT_Face face;
*
* FT_Long num_faces = 0;
* FT_Long num_instances = 0;
*
* FT_Long face_idx = 0;
* FT_Long instance_idx = 0;
*
*
* do
* {
* FT_Long id = ( instance_idx << 16 ) + face_idx;
*
*
* error = FT_Open_Face( library, args, id, &face );
* if ( error ) { ... }
*
* num_faces = face->num_faces;
* num_instances = face->style_flags >> 16;
*
* ...
*
* FT_Done_Face( face );
*
* if ( instance_idx < num_instances )
* instance_idx++;
* else
* {
* face_idx++;
* instance_idx = 0;
* }
*
* } while ( face_idx < num_faces )
* ```
*/
FT_EXPORT( FT_Error )
FT_Open_Face( FT_Library library,
const FT_Open_Args* args,
FT_Long face_index,
FT_Face *aface );
/**************************************************************************
*
* @function:
* FT_Attach_File
*
* @description:
* Call @FT_Attach_Stream to attach a file.
*
* @inout:
* face ::
* The target face object.
*
* @input:
* filepathname ::
* The pathname.
*
* @return:
* FreeType error code. 0~means success.
*/
FT_EXPORT( FT_Error )
FT_Attach_File( FT_Face face,
const char* filepathname );
/**************************************************************************
*
* @function:
* FT_Attach_Stream
*
* @description:
* 'Attach' data to a face object. Normally, this is used to read
* additional information for the face object. For example, you can
* attach an AFM file that comes with a Type~1 font to get the kerning
* values and other metrics.
*
* @inout:
* face ::
* The target face object.
*
* @input:
* parameters ::
* A pointer to @FT_Open_Args that must be filled by the caller.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* The meaning of the 'attach' (i.e., what really happens when the new
* file is read) is not fixed by FreeType itself. It really depends on
* the font format (and thus the font driver).
*
* Client applications are expected to know what they are doing when
* invoking this function. Most drivers simply do not implement file or
* stream attachments.
*/
FT_EXPORT( FT_Error )
FT_Attach_Stream( FT_Face face,
FT_Open_Args* parameters );
/**************************************************************************
*
* @function:
* FT_Reference_Face
*
* @description:
* A counter gets initialized to~1 at the time an @FT_Face structure is
* created. This function increments the counter. @FT_Done_Face then
* only destroys a face if the counter is~1, otherwise it simply
* decrements the counter.
*
* This function helps in managing life-cycles of structures that
* reference @FT_Face objects.
*
* @input:
* face ::
* A handle to a target face object.
*
* @return:
* FreeType error code. 0~means success.
*
* @since:
* 2.4.2
*/
FT_EXPORT( FT_Error )
FT_Reference_Face( FT_Face face );
/**************************************************************************
*
* @function:
* FT_Done_Face
*
* @description:
* Discard a given face object, as well as all of its child slots and
* sizes.
*
* @input:
* face ::
* A handle to a target face object.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* See the discussion of reference counters in the description of
* @FT_Reference_Face.
*/
FT_EXPORT( FT_Error )
FT_Done_Face( FT_Face face );
/**************************************************************************
*
* @function:
* FT_Select_Size
*
* @description:
* Select a bitmap strike. To be more precise, this function sets the
* scaling factors of the active @FT_Size object in a face so that
* bitmaps from this particular strike are taken by @FT_Load_Glyph and
* friends.
*
* @inout:
* face ::
* A handle to a target face object.
*
* @input:
* strike_index ::
* The index of the bitmap strike in the `available_sizes` field of
* @FT_FaceRec structure.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* For bitmaps embedded in outline fonts it is common that only a subset
* of the available glyphs at a given ppem value is available. FreeType
* silently uses outlines if there is no bitmap for a given glyph index.
*
* For GX and OpenType variation fonts, a bitmap strike makes sense only
* if the default instance is active (this is, no glyph variation takes
* place); otherwise, FreeType simply ignores bitmap strikes. The same
* is true for all named instances that are different from the default
* instance.
*
* Don't use this function if you are using the FreeType cache API.
*/
FT_EXPORT( FT_Error )
FT_Select_Size( FT_Face face,
FT_Int strike_index );
/**************************************************************************
*
* @enum:
* FT_Size_Request_Type
*
* @description:
* An enumeration type that lists the supported size request types, i.e.,
* what input size (in font units) maps to the requested output size (in
* pixels, as computed from the arguments of @FT_Size_Request).
*
* @values:
* FT_SIZE_REQUEST_TYPE_NOMINAL ::
* The nominal size. The `units_per_EM` field of @FT_FaceRec is used
* to determine both scaling values.
*
* This is the standard scaling found in most applications. In
* particular, use this size request type for TrueType fonts if they
* provide optical scaling or something similar. Note, however, that
* `units_per_EM` is a rather abstract value which bears no relation to
* the actual size of the glyphs in a font.
*
* FT_SIZE_REQUEST_TYPE_REAL_DIM ::
* The real dimension. The sum of the `ascender` and (minus of) the
* `descender` fields of @FT_FaceRec is used to determine both scaling
* values.
*
* FT_SIZE_REQUEST_TYPE_BBOX ::
* The font bounding box. The width and height of the `bbox` field of
* @FT_FaceRec are used to determine the horizontal and vertical
* scaling value, respectively.
*
* FT_SIZE_REQUEST_TYPE_CELL ::
* The `max_advance_width` field of @FT_FaceRec is used to determine
* the horizontal scaling value; the vertical scaling value is
* determined the same way as @FT_SIZE_REQUEST_TYPE_REAL_DIM does.
* Finally, both scaling values are set to the smaller one. This type
* is useful if you want to specify the font size for, say, a window of
* a given dimension and 80x24 cells.
*
* FT_SIZE_REQUEST_TYPE_SCALES ::
* Specify the scaling values directly.
*
* @note:
* The above descriptions only apply to scalable formats. For bitmap
* formats, the behaviour is up to the driver.
*
* See the note section of @FT_Size_Metrics if you wonder how size
* requesting relates to scaling values.
*/
typedef enum FT_Size_Request_Type_
{
FT_SIZE_REQUEST_TYPE_NOMINAL,
FT_SIZE_REQUEST_TYPE_REAL_DIM,
FT_SIZE_REQUEST_TYPE_BBOX,
FT_SIZE_REQUEST_TYPE_CELL,
FT_SIZE_REQUEST_TYPE_SCALES,
FT_SIZE_REQUEST_TYPE_MAX
} FT_Size_Request_Type;
/**************************************************************************
*
* @struct:
* FT_Size_RequestRec
*
* @description:
* A structure to model a size request.
*
* @fields:
* type ::
* See @FT_Size_Request_Type.
*
* width ::
* The desired width, given as a 26.6 fractional point value (with 72pt
* = 1in).
*
* height ::
* The desired height, given as a 26.6 fractional point value (with
* 72pt = 1in).
*
* horiResolution ::
* The horizontal resolution (dpi, i.e., pixels per inch). If set to
* zero, `width` is treated as a 26.6 fractional **pixel** value, which
* gets internally rounded to an integer.
*
* vertResolution ::
* The vertical resolution (dpi, i.e., pixels per inch). If set to
* zero, `height` is treated as a 26.6 fractional **pixel** value,
* which gets internally rounded to an integer.
*
* @note:
* If `width` is zero, the horizontal scaling value is set equal to the
* vertical scaling value, and vice versa.
*
* If `type` is `FT_SIZE_REQUEST_TYPE_SCALES`, `width` and `height` are
* interpreted directly as 16.16 fractional scaling values, without any
* further modification, and both `horiResolution` and `vertResolution`
* are ignored.
*/
typedef struct FT_Size_RequestRec_
{
FT_Size_Request_Type type;
FT_Long width;
FT_Long height;
FT_UInt horiResolution;
FT_UInt vertResolution;
} FT_Size_RequestRec;
/**************************************************************************
*
* @struct:
* FT_Size_Request
*
* @description:
* A handle to a size request structure.
*/
typedef struct FT_Size_RequestRec_ *FT_Size_Request;
/**************************************************************************
*
* @function:
* FT_Request_Size
*
* @description:
* Resize the scale of the active @FT_Size object in a face.
*
* @inout:
* face ::
* A handle to a target face object.
*
* @input:
* req ::
* A pointer to a @FT_Size_RequestRec.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Although drivers may select the bitmap strike matching the request,
* you should not rely on this if you intend to select a particular
* bitmap strike. Use @FT_Select_Size instead in that case.
*
* The relation between the requested size and the resulting glyph size
* is dependent entirely on how the size is defined in the source face.
* The font designer chooses the final size of each glyph relative to
* this size. For more information refer to
* 'https://www.freetype.org/freetype2/docs/glyphs/glyphs-2.html'.
*
* Contrary to @FT_Set_Char_Size, this function doesn't have special code
* to normalize zero-valued widths, heights, or resolutions (which lead
* to errors in most cases).
*
* Don't use this function if you are using the FreeType cache API.
*/
FT_EXPORT( FT_Error )
FT_Request_Size( FT_Face face,
FT_Size_Request req );
/**************************************************************************
*
* @function:
* FT_Set_Char_Size
*
* @description:
* Call @FT_Request_Size to request the nominal size (in points).
*
* @inout:
* face ::
* A handle to a target face object.
*
* @input:
* char_width ::
* The nominal width, in 26.6 fractional points.
*
* char_height ::
* The nominal height, in 26.6 fractional points.
*
* horz_resolution ::
* The horizontal resolution in dpi.
*
* vert_resolution ::
* The vertical resolution in dpi.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* While this function allows fractional points as input values, the
* resulting ppem value for the given resolution is always rounded to the
* nearest integer.
*
* If either the character width or height is zero, it is set equal to
* the other value.
*
* If either the horizontal or vertical resolution is zero, it is set
* equal to the other value.
*
* A character width or height smaller than 1pt is set to 1pt; if both
* resolution values are zero, they are set to 72dpi.
*
* Don't use this function if you are using the FreeType cache API.
*/
FT_EXPORT( FT_Error )
FT_Set_Char_Size( FT_Face face,
FT_F26Dot6 char_width,
FT_F26Dot6 char_height,
FT_UInt horz_resolution,
FT_UInt vert_resolution );
/**************************************************************************
*
* @function:
* FT_Set_Pixel_Sizes
*
* @description:
* Call @FT_Request_Size to request the nominal size (in pixels).
*
* @inout:
* face ::
* A handle to the target face object.
*
* @input:
* pixel_width ::
* The nominal width, in pixels.
*
* pixel_height ::
* The nominal height, in pixels.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* You should not rely on the resulting glyphs matching or being
* constrained to this pixel size. Refer to @FT_Request_Size to
* understand how requested sizes relate to actual sizes.
*
* Don't use this function if you are using the FreeType cache API.
*/
FT_EXPORT( FT_Error )
FT_Set_Pixel_Sizes( FT_Face face,
FT_UInt pixel_width,
FT_UInt pixel_height );
/**************************************************************************
*
* @function:
* FT_Load_Glyph
*
* @description:
* Load a glyph into the glyph slot of a face object.
*
* @inout:
* face ::
* A handle to the target face object where the glyph is loaded.
*
* @input:
* glyph_index ::
* The index of the glyph in the font file. For CID-keyed fonts
* (either in PS or in CFF format) this argument specifies the CID
* value.
*
* load_flags ::
* A flag indicating what to load for this glyph. The @FT_LOAD_XXX
* constants can be used to control the glyph loading process (e.g.,
* whether the outline should be scaled, whether to load bitmaps or
* not, whether to hint the outline, etc).
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* The loaded glyph may be transformed. See @FT_Set_Transform for the
* details.
*
* For subsetted CID-keyed fonts, `FT_Err_Invalid_Argument` is returned
* for invalid CID values (this is, for CID values that don't have a
* corresponding glyph in the font). See the discussion of the
* @FT_FACE_FLAG_CID_KEYED flag for more details.
*
* If you receive `FT_Err_Glyph_Too_Big`, try getting the glyph outline
* at EM size, then scale it manually and fill it as a graphics
* operation.
*/
FT_EXPORT( FT_Error )
FT_Load_Glyph( FT_Face face,
FT_UInt glyph_index,
FT_Int32 load_flags );
/**************************************************************************
*
* @function:
* FT_Load_Char
*
* @description:
* Load a glyph into the glyph slot of a face object, accessed by its
* character code.
*
* @inout:
* face ::
* A handle to a target face object where the glyph is loaded.
*
* @input:
* char_code ::
* The glyph's character code, according to the current charmap used in
* the face.
*
* load_flags ::
* A flag indicating what to load for this glyph. The @FT_LOAD_XXX
* constants can be used to control the glyph loading process (e.g.,
* whether the outline should be scaled, whether to load bitmaps or
* not, whether to hint the outline, etc).
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* This function simply calls @FT_Get_Char_Index and @FT_Load_Glyph.
*
* Many fonts contain glyphs that can't be loaded by this function since
* its glyph indices are not listed in any of the font's charmaps.
*
* If no active cmap is set up (i.e., `face->charmap` is zero), the call
* to @FT_Get_Char_Index is omitted, and the function behaves identically
* to @FT_Load_Glyph.
*/
FT_EXPORT( FT_Error )
FT_Load_Char( FT_Face face,
FT_ULong char_code,
FT_Int32 load_flags );
/**************************************************************************
*
* @enum:
* FT_LOAD_XXX
*
* @description:
* A list of bit field constants for @FT_Load_Glyph to indicate what kind
* of operations to perform during glyph loading.
*
* @values:
* FT_LOAD_DEFAULT ::
* Corresponding to~0, this value is used as the default glyph load
* operation. In this case, the following happens:
*
* 1. FreeType looks for a bitmap for the glyph corresponding to the
* face's current size. If one is found, the function returns. The
* bitmap data can be accessed from the glyph slot (see note below).
*
* 2. If no embedded bitmap is searched for or found, FreeType looks
* for a scalable outline. If one is found, it is loaded from the font
* file, scaled to device pixels, then 'hinted' to the pixel grid in
* order to optimize it. The outline data can be accessed from the
* glyph slot (see note below).
*
* Note that by default the glyph loader doesn't render outlines into
* bitmaps. The following flags are used to modify this default
* behaviour to more specific and useful cases.
*
* FT_LOAD_NO_SCALE ::
* Don't scale the loaded outline glyph but keep it in font units.
*
* This flag implies @FT_LOAD_NO_HINTING and @FT_LOAD_NO_BITMAP, and
* unsets @FT_LOAD_RENDER.
*
* If the font is 'tricky' (see @FT_FACE_FLAG_TRICKY for more), using
* `FT_LOAD_NO_SCALE` usually yields meaningless outlines because the
* subglyphs must be scaled and positioned with hinting instructions.
* This can be solved by loading the font without `FT_LOAD_NO_SCALE`
* and setting the character size to `font->units_per_EM`.
*
* FT_LOAD_NO_HINTING ::
* Disable hinting. This generally generates 'blurrier' bitmap glyphs
* when the glyph are rendered in any of the anti-aliased modes. See
* also the note below.
*
* This flag is implied by @FT_LOAD_NO_SCALE.
*
* FT_LOAD_RENDER ::
* Call @FT_Render_Glyph after the glyph is loaded. By default, the
* glyph is rendered in @FT_RENDER_MODE_NORMAL mode. This can be
* overridden by @FT_LOAD_TARGET_XXX or @FT_LOAD_MONOCHROME.
*
* This flag is unset by @FT_LOAD_NO_SCALE.
*
* FT_LOAD_NO_BITMAP ::
* Ignore bitmap strikes when loading. Bitmap-only fonts ignore this
* flag.
*
* @FT_LOAD_NO_SCALE always sets this flag.
*
* FT_LOAD_VERTICAL_LAYOUT ::
* Load the glyph for vertical text layout. In particular, the
* `advance` value in the @FT_GlyphSlotRec structure is set to the
* `vertAdvance` value of the `metrics` field.
*
* In case @FT_HAS_VERTICAL doesn't return true, you shouldn't use this
* flag currently. Reason is that in this case vertical metrics get
* synthesized, and those values are not always consistent across
* various font formats.
*
* FT_LOAD_FORCE_AUTOHINT ::
* Prefer the auto-hinter over the font's native hinter. See also the
* note below.
*
* FT_LOAD_PEDANTIC ::
* Make the font driver perform pedantic verifications during glyph
* loading and hinting. This is mostly used to detect broken glyphs in
* fonts. By default, FreeType tries to handle broken fonts also.
*
* In particular, errors from the TrueType bytecode engine are not
* passed to the application if this flag is not set; this might result
* in partially hinted or distorted glyphs in case a glyph's bytecode
* is buggy.
*
* FT_LOAD_NO_RECURSE ::
* Don't load composite glyphs recursively. Instead, the font driver
* fills the `num_subglyph` and `subglyphs` values of the glyph slot;
* it also sets `glyph->format` to @FT_GLYPH_FORMAT_COMPOSITE. The
* description of subglyphs can then be accessed with
* @FT_Get_SubGlyph_Info.
*
* Don't use this flag for retrieving metrics information since some
* font drivers only return rudimentary data.
*
* This flag implies @FT_LOAD_NO_SCALE and @FT_LOAD_IGNORE_TRANSFORM.
*
* FT_LOAD_IGNORE_TRANSFORM ::
* Ignore the transform matrix set by @FT_Set_Transform.
*
* FT_LOAD_MONOCHROME ::
* This flag is used with @FT_LOAD_RENDER to indicate that you want to
* render an outline glyph to a 1-bit monochrome bitmap glyph, with
* 8~pixels packed into each byte of the bitmap data.
*
* Note that this has no effect on the hinting algorithm used. You
* should rather use @FT_LOAD_TARGET_MONO so that the
* monochrome-optimized hinting algorithm is used.
*
* FT_LOAD_LINEAR_DESIGN ::
* Keep `linearHoriAdvance` and `linearVertAdvance` fields of
* @FT_GlyphSlotRec in font units. See @FT_GlyphSlotRec for details.
*
* FT_LOAD_NO_AUTOHINT ::
* Disable the auto-hinter. See also the note below.
*
* FT_LOAD_COLOR ::
* Load colored glyphs. There are slight differences depending on the
* font format.
*
* [Since 2.5] Load embedded color bitmap images. The resulting color
* bitmaps, if available, will have the @FT_PIXEL_MODE_BGRA format,
* with pre-multiplied color channels. If the flag is not set and
* color bitmaps are found, they are converted to 256-level gray
* bitmaps, using the @FT_PIXEL_MODE_GRAY format.
*
* [Since 2.10, experimental] If the glyph index contains an entry in
* the face's 'COLR' table with a 'CPAL' palette table (as defined in
* the OpenType specification), make @FT_Render_Glyph provide a default
* blending of the color glyph layers associated with the glyph index,
* using the same bitmap format as embedded color bitmap images. This
* is mainly for convenience; for full control of color layers use
* @FT_Get_Color_Glyph_Layer and FreeType's color functions like
* @FT_Palette_Select instead of setting @FT_LOAD_COLOR for rendering
* so that the client application can handle blending by itself.
*
* FT_LOAD_COMPUTE_METRICS ::
* [Since 2.6.1] Compute glyph metrics from the glyph data, without the
* use of bundled metrics tables (for example, the 'hdmx' table in
* TrueType fonts). This flag is mainly used by font validating or
* font editing applications, which need to ignore, verify, or edit
* those tables.
*
* Currently, this flag is only implemented for TrueType fonts.
*
* FT_LOAD_BITMAP_METRICS_ONLY ::
* [Since 2.7.1] Request loading of the metrics and bitmap image
* information of a (possibly embedded) bitmap glyph without allocating
* or copying the bitmap image data itself. No effect if the target
* glyph is not a bitmap image.
*
* This flag unsets @FT_LOAD_RENDER.
*
* FT_LOAD_CROP_BITMAP ::
* Ignored. Deprecated.
*
* FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH ::
* Ignored. Deprecated.
*
* @note:
* By default, hinting is enabled and the font's native hinter (see
* @FT_FACE_FLAG_HINTER) is preferred over the auto-hinter. You can
* disable hinting by setting @FT_LOAD_NO_HINTING or change the
* precedence by setting @FT_LOAD_FORCE_AUTOHINT. You can also set
* @FT_LOAD_NO_AUTOHINT in case you don't want the auto-hinter to be used
* at all.
*
* See the description of @FT_FACE_FLAG_TRICKY for a special exception
* (affecting only a handful of Asian fonts).
*
* Besides deciding which hinter to use, you can also decide which
* hinting algorithm to use. See @FT_LOAD_TARGET_XXX for details.
*
* Note that the auto-hinter needs a valid Unicode cmap (either a native
* one or synthesized by FreeType) for producing correct results. If a
* font provides an incorrect mapping (for example, assigning the
* character code U+005A, LATIN CAPITAL LETTER~Z, to a glyph depicting a
* mathematical integral sign), the auto-hinter might produce useless
* results.
*
*/
#define FT_LOAD_DEFAULT 0x0
#define FT_LOAD_NO_SCALE ( 1L << 0 )
#define FT_LOAD_NO_HINTING ( 1L << 1 )
#define FT_LOAD_RENDER ( 1L << 2 )
#define FT_LOAD_NO_BITMAP ( 1L << 3 )
#define FT_LOAD_VERTICAL_LAYOUT ( 1L << 4 )
#define FT_LOAD_FORCE_AUTOHINT ( 1L << 5 )
#define FT_LOAD_CROP_BITMAP ( 1L << 6 )
#define FT_LOAD_PEDANTIC ( 1L << 7 )
#define FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH ( 1L << 9 )
#define FT_LOAD_NO_RECURSE ( 1L << 10 )
#define FT_LOAD_IGNORE_TRANSFORM ( 1L << 11 )
#define FT_LOAD_MONOCHROME ( 1L << 12 )
#define FT_LOAD_LINEAR_DESIGN ( 1L << 13 )
#define FT_LOAD_NO_AUTOHINT ( 1L << 15 )
/* Bits 16-19 are used by `FT_LOAD_TARGET_` */
#define FT_LOAD_COLOR ( 1L << 20 )
#define FT_LOAD_COMPUTE_METRICS ( 1L << 21 )
#define FT_LOAD_BITMAP_METRICS_ONLY ( 1L << 22 )
/* */
/* used internally only by certain font drivers */
#define FT_LOAD_ADVANCE_ONLY ( 1L << 8 )
#define FT_LOAD_SBITS_ONLY ( 1L << 14 )
/**************************************************************************
*
* @enum:
* FT_LOAD_TARGET_XXX
*
* @description:
* A list of values to select a specific hinting algorithm for the
* hinter. You should OR one of these values to your `load_flags` when
* calling @FT_Load_Glyph.
*
* Note that a font's native hinters may ignore the hinting algorithm you
* have specified (e.g., the TrueType bytecode interpreter). You can set
* @FT_LOAD_FORCE_AUTOHINT to ensure that the auto-hinter is used.
*
* @values:
* FT_LOAD_TARGET_NORMAL ::
* The default hinting algorithm, optimized for standard gray-level
* rendering. For monochrome output, use @FT_LOAD_TARGET_MONO instead.
*
* FT_LOAD_TARGET_LIGHT ::
* A lighter hinting algorithm for gray-level modes. Many generated
* glyphs are fuzzier but better resemble their original shape. This
* is achieved by snapping glyphs to the pixel grid only vertically
* (Y-axis), as is done by FreeType's new CFF engine or Microsoft's
* ClearType font renderer. This preserves inter-glyph spacing in
* horizontal text. The snapping is done either by the native font
* driver, if the driver itself and the font support it, or by the
* auto-hinter.
*
* Advance widths are rounded to integer values; however, using the
* `lsb_delta` and `rsb_delta` fields of @FT_GlyphSlotRec, it is
* possible to get fractional advance widths for subpixel positioning
* (which is recommended to use).
*
* If configuration option `AF_CONFIG_OPTION_TT_SIZE_METRICS` is
* active, TrueType-like metrics are used to make this mode behave
* similarly as in unpatched FreeType versions between 2.4.6 and 2.7.1
* (inclusive).
*
* FT_LOAD_TARGET_MONO ::
* Strong hinting algorithm that should only be used for monochrome
* output. The result is probably unpleasant if the glyph is rendered
* in non-monochrome modes.
*
* Note that for outline fonts only the TrueType font driver has proper
* monochrome hinting support, provided the TTFs contain hints for B/W
* rendering (which most fonts no longer provide). If these conditions
* are not met it is very likely that you get ugly results at smaller
* sizes.
*
* FT_LOAD_TARGET_LCD ::
* A variant of @FT_LOAD_TARGET_LIGHT optimized for horizontally
* decimated LCD displays.
*
* FT_LOAD_TARGET_LCD_V ::
* A variant of @FT_LOAD_TARGET_NORMAL optimized for vertically
* decimated LCD displays.
*
* @note:
* You should use only _one_ of the `FT_LOAD_TARGET_XXX` values in your
* `load_flags`. They can't be ORed.
*
* If @FT_LOAD_RENDER is also set, the glyph is rendered in the
* corresponding mode (i.e., the mode that matches the used algorithm
* best). An exception is `FT_LOAD_TARGET_MONO` since it implies
* @FT_LOAD_MONOCHROME.
*
* You can use a hinting algorithm that doesn't correspond to the same
* rendering mode. As an example, it is possible to use the 'light'
* hinting algorithm and have the results rendered in horizontal LCD
* pixel mode, with code like
*
* ```
* FT_Load_Glyph( face, glyph_index,
* load_flags | FT_LOAD_TARGET_LIGHT );
*
* FT_Render_Glyph( face->glyph, FT_RENDER_MODE_LCD );
* ```
*
* In general, you should stick with one rendering mode. For example,
* switching between @FT_LOAD_TARGET_NORMAL and @FT_LOAD_TARGET_MONO
* enforces a lot of recomputation for TrueType fonts, which is slow.
* Another reason is caching: Selecting a different mode usually causes
* changes in both the outlines and the rasterized bitmaps; it is thus
* necessary to empty the cache after a mode switch to avoid false hits.
*
*/
#define FT_LOAD_TARGET_( x ) ( (FT_Int32)( (x) & 15 ) << 16 )
#define FT_LOAD_TARGET_NORMAL FT_LOAD_TARGET_( FT_RENDER_MODE_NORMAL )
#define FT_LOAD_TARGET_LIGHT FT_LOAD_TARGET_( FT_RENDER_MODE_LIGHT )
#define FT_LOAD_TARGET_MONO FT_LOAD_TARGET_( FT_RENDER_MODE_MONO )
#define FT_LOAD_TARGET_LCD FT_LOAD_TARGET_( FT_RENDER_MODE_LCD )
#define FT_LOAD_TARGET_LCD_V FT_LOAD_TARGET_( FT_RENDER_MODE_LCD_V )
/**************************************************************************
*
* @macro:
* FT_LOAD_TARGET_MODE
*
* @description:
* Return the @FT_Render_Mode corresponding to a given
* @FT_LOAD_TARGET_XXX value.
*
*/
#define FT_LOAD_TARGET_MODE( x ) ( (FT_Render_Mode)( ( (x) >> 16 ) & 15 ) )
/**************************************************************************
*
* @function:
* FT_Set_Transform
*
* @description:
* Set the transformation that is applied to glyph images when they are
* loaded into a glyph slot through @FT_Load_Glyph.
*
* @inout:
* face ::
* A handle to the source face object.
*
* @input:
* matrix ::
* A pointer to the transformation's 2x2 matrix. Use `NULL` for the
* identity matrix.
* delta ::
* A pointer to the translation vector. Use `NULL` for the null vector.
*
* @note:
* This function is provided as a convenience, but keep in mind that
* @FT_Matrix coefficients are only 16.16 fixed point values, which can
* limit the accuracy of the results. Using floating-point computations
* to perform the transform directly in client code instead will always
* yield better numbers.
*
* The transformation is only applied to scalable image formats after the
* glyph has been loaded. It means that hinting is unaltered by the
* transformation and is performed on the character size given in the
* last call to @FT_Set_Char_Size or @FT_Set_Pixel_Sizes.
*
* Note that this also transforms the `face.glyph.advance` field, but
* **not** the values in `face.glyph.metrics`.
*/
FT_EXPORT( void )
FT_Set_Transform( FT_Face face,
FT_Matrix* matrix,
FT_Vector* delta );
/**************************************************************************
*
* @enum:
* FT_Render_Mode
*
* @description:
* Render modes supported by FreeType~2. Each mode corresponds to a
* specific type of scanline conversion performed on the outline.
*
* For bitmap fonts and embedded bitmaps the `bitmap->pixel_mode` field
* in the @FT_GlyphSlotRec structure gives the format of the returned
* bitmap.
*
* All modes except @FT_RENDER_MODE_MONO use 256 levels of opacity,
* indicating pixel coverage. Use linear alpha blending and gamma
* correction to correctly render non-monochrome glyph bitmaps onto a
* surface; see @FT_Render_Glyph.
*
* @values:
* FT_RENDER_MODE_NORMAL ::
* Default render mode; it corresponds to 8-bit anti-aliased bitmaps.
*
* FT_RENDER_MODE_LIGHT ::
* This is equivalent to @FT_RENDER_MODE_NORMAL. It is only defined as
* a separate value because render modes are also used indirectly to
* define hinting algorithm selectors. See @FT_LOAD_TARGET_XXX for
* details.
*
* FT_RENDER_MODE_MONO ::
* This mode corresponds to 1-bit bitmaps (with 2~levels of opacity).
*
* FT_RENDER_MODE_LCD ::
* This mode corresponds to horizontal RGB and BGR subpixel displays
* like LCD screens. It produces 8-bit bitmaps that are 3~times the
* width of the original glyph outline in pixels, and which use the
* @FT_PIXEL_MODE_LCD mode.
*
* FT_RENDER_MODE_LCD_V ::
* This mode corresponds to vertical RGB and BGR subpixel displays
* (like PDA screens, rotated LCD displays, etc.). It produces 8-bit
* bitmaps that are 3~times the height of the original glyph outline in
* pixels and use the @FT_PIXEL_MODE_LCD_V mode.
*
* @note:
* The selected render mode only affects vector glyphs of a font.
* Embedded bitmaps often have a different pixel mode like
* @FT_PIXEL_MODE_MONO. You can use @FT_Bitmap_Convert to transform them
* into 8-bit pixmaps.
*/
typedef enum FT_Render_Mode_
{
FT_RENDER_MODE_NORMAL = 0,
FT_RENDER_MODE_LIGHT,
FT_RENDER_MODE_MONO,
FT_RENDER_MODE_LCD,
FT_RENDER_MODE_LCD_V,
FT_RENDER_MODE_MAX
} FT_Render_Mode;
/* these constants are deprecated; use the corresponding */
/* `FT_Render_Mode` values instead */
#define ft_render_mode_normal FT_RENDER_MODE_NORMAL
#define ft_render_mode_mono FT_RENDER_MODE_MONO
/**************************************************************************
*
* @function:
* FT_Render_Glyph
*
* @description:
* Convert a given glyph image to a bitmap. It does so by inspecting the
* glyph image format, finding the relevant renderer, and invoking it.
*
* @inout:
* slot ::
* A handle to the glyph slot containing the image to convert.
*
* @input:
* render_mode ::
* The render mode used to render the glyph image into a bitmap. See
* @FT_Render_Mode for a list of possible values.
*
* If @FT_RENDER_MODE_NORMAL is used, a previous call of @FT_Load_Glyph
* with flag @FT_LOAD_COLOR makes FT_Render_Glyph provide a default
* blending of colored glyph layers associated with the current glyph
* slot (provided the font contains such layers) instead of rendering
* the glyph slot's outline. This is an experimental feature; see
* @FT_LOAD_COLOR for more information.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* To get meaningful results, font scaling values must be set with
* functions like @FT_Set_Char_Size before calling `FT_Render_Glyph`.
*
* When FreeType outputs a bitmap of a glyph, it really outputs an alpha
* coverage map. If a pixel is completely covered by a filled-in
* outline, the bitmap contains 0xFF at that pixel, meaning that
* 0xFF/0xFF fraction of that pixel is covered, meaning the pixel is 100%
* black (or 0% bright). If a pixel is only 50% covered (value 0x80),
* the pixel is made 50% black (50% bright or a middle shade of grey).
* 0% covered means 0% black (100% bright or white).
*
* On high-DPI screens like on smartphones and tablets, the pixels are so
* small that their chance of being completely covered and therefore
* completely black are fairly good. On the low-DPI screens, however,
* the situation is different. The pixels are too large for most of the
* details of a glyph and shades of gray are the norm rather than the
* exception.
*
* This is relevant because all our screens have a second problem: they
* are not linear. 1~+~1 is not~2. Twice the value does not result in
* twice the brightness. When a pixel is only 50% covered, the coverage
* map says 50% black, and this translates to a pixel value of 128 when
* you use 8~bits per channel (0-255). However, this does not translate
* to 50% brightness for that pixel on our sRGB and gamma~2.2 screens.
* Due to their non-linearity, they dwell longer in the darks and only a
* pixel value of about 186 results in 50% brightness -- 128 ends up too
* dark on both bright and dark backgrounds. The net result is that dark
* text looks burnt-out, pixely and blotchy on bright background, bright
* text too frail on dark backgrounds, and colored text on colored
* background (for example, red on green) seems to have dark halos or
* 'dirt' around it. The situation is especially ugly for diagonal stems
* like in 'w' glyph shapes where the quality of FreeType's anti-aliasing
* depends on the correct display of grays. On high-DPI screens where
* smaller, fully black pixels reign supreme, this doesn't matter, but on
* our low-DPI screens with all the gray shades, it does. 0% and 100%
* brightness are the same things in linear and non-linear space, just
* all the shades in-between aren't.
*
* The blending function for placing text over a background is
*
* ```
* dst = alpha * src + (1 - alpha) * dst ,
* ```
*
* which is known as the OVER operator.
*
* To correctly composite an antialiased pixel of a glyph onto a surface,
*
* 1. take the foreground and background colors (e.g., in sRGB space)
* and apply gamma to get them in a linear space,
*
* 2. use OVER to blend the two linear colors using the glyph pixel
* as the alpha value (remember, the glyph bitmap is an alpha coverage
* bitmap), and
*
* 3. apply inverse gamma to the blended pixel and write it back to
* the image.
*
* Internal testing at Adobe found that a target inverse gamma of~1.8 for
* step~3 gives good results across a wide range of displays with an sRGB
* gamma curve or a similar one.
*
* This process can cost performance. There is an approximation that
* does not need to know about the background color; see
* https://bel.fi/alankila/lcd/ and
* https://bel.fi/alankila/lcd/alpcor.html for details.
*
* **ATTENTION**: Linear blending is even more important when dealing
* with subpixel-rendered glyphs to prevent color-fringing! A
* subpixel-rendered glyph must first be filtered with a filter that
* gives equal weight to the three color primaries and does not exceed a
* sum of 0x100, see section @lcd_rendering. Then the only difference to
* gray linear blending is that subpixel-rendered linear blending is done
* 3~times per pixel: red foreground subpixel to red background subpixel
* and so on for green and blue.
*/
FT_EXPORT( FT_Error )
FT_Render_Glyph( FT_GlyphSlot slot,
FT_Render_Mode render_mode );
/**************************************************************************
*
* @enum:
* FT_Kerning_Mode
*
* @description:
* An enumeration to specify the format of kerning values returned by
* @FT_Get_Kerning.
*
* @values:
* FT_KERNING_DEFAULT ::
* Return grid-fitted kerning distances in 26.6 fractional pixels.
*
* FT_KERNING_UNFITTED ::
* Return un-grid-fitted kerning distances in 26.6 fractional pixels.
*
* FT_KERNING_UNSCALED ::
* Return the kerning vector in original font units.
*
* @note:
* `FT_KERNING_DEFAULT` returns full pixel values; it also makes FreeType
* heuristically scale down kerning distances at small ppem values so
* that they don't become too big.
*
* Both `FT_KERNING_DEFAULT` and `FT_KERNING_UNFITTED` use the current
* horizontal scaling factor (as set e.g. with @FT_Set_Char_Size) to
* convert font units to pixels.
*/
typedef enum FT_Kerning_Mode_
{
FT_KERNING_DEFAULT = 0,
FT_KERNING_UNFITTED,
FT_KERNING_UNSCALED
} FT_Kerning_Mode;
/* these constants are deprecated; use the corresponding */
/* `FT_Kerning_Mode` values instead */
#define ft_kerning_default FT_KERNING_DEFAULT
#define ft_kerning_unfitted FT_KERNING_UNFITTED
#define ft_kerning_unscaled FT_KERNING_UNSCALED
/**************************************************************************
*
* @function:
* FT_Get_Kerning
*
* @description:
* Return the kerning vector between two glyphs of the same face.
*
* @input:
* face ::
* A handle to a source face object.
*
* left_glyph ::
* The index of the left glyph in the kern pair.
*
* right_glyph ::
* The index of the right glyph in the kern pair.
*
* kern_mode ::
* See @FT_Kerning_Mode for more information. Determines the scale and
* dimension of the returned kerning vector.
*
* @output:
* akerning ::
* The kerning vector. This is either in font units, fractional pixels
* (26.6 format), or pixels for scalable formats, and in pixels for
* fixed-sizes formats.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Only horizontal layouts (left-to-right & right-to-left) are supported
* by this method. Other layouts, or more sophisticated kernings, are
* out of the scope of this API function -- they can be implemented
* through format-specific interfaces.
*
* Kerning for OpenType fonts implemented in a 'GPOS' table is not
* supported; use @FT_HAS_KERNING to find out whether a font has data
* that can be extracted with `FT_Get_Kerning`.
*/
FT_EXPORT( FT_Error )
FT_Get_Kerning( FT_Face face,
FT_UInt left_glyph,
FT_UInt right_glyph,
FT_UInt kern_mode,
FT_Vector *akerning );
/**************************************************************************
*
* @function:
* FT_Get_Track_Kerning
*
* @description:
* Return the track kerning for a given face object at a given size.
*
* @input:
* face ::
* A handle to a source face object.
*
* point_size ::
* The point size in 16.16 fractional points.
*
* degree ::
* The degree of tightness. Increasingly negative values represent
* tighter track kerning, while increasingly positive values represent
* looser track kerning. Value zero means no track kerning.
*
* @output:
* akerning ::
* The kerning in 16.16 fractional points, to be uniformly applied
* between all glyphs.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Currently, only the Type~1 font driver supports track kerning, using
* data from AFM files (if attached with @FT_Attach_File or
* @FT_Attach_Stream).
*
* Only very few AFM files come with track kerning data; please refer to
* Adobe's AFM specification for more details.
*/
FT_EXPORT( FT_Error )
FT_Get_Track_Kerning( FT_Face face,
FT_Fixed point_size,
FT_Int degree,
FT_Fixed* akerning );
/**************************************************************************
*
* @function:
* FT_Get_Glyph_Name