ref: e990c33f218dc7ca619444e17b0bf5085b4b727c
dir: /src/truetype/ttobjs.h/
/****************************************************************************
*
* ttobjs.h
*
* Objects manager (specification).
*
* Copyright (C) 1996-2021 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#ifndef TTOBJS_H_
#define TTOBJS_H_
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/tttypes.h>
FT_BEGIN_HEADER
/**************************************************************************
*
* @Type:
* TT_Driver
*
* @Description:
* A handle to a TrueType driver object.
*/
typedef struct TT_DriverRec_* TT_Driver;
/**************************************************************************
*
* @Type:
* TT_GlyphSlot
*
* @Description:
* A handle to a TrueType glyph slot object.
*
* @Note:
* This is a direct typedef of FT_GlyphSlot, as there is nothing
* specific about the TrueType glyph slot.
*/
typedef FT_GlyphSlot TT_GlyphSlot;
/**************************************************************************
*
* @Struct:
* TT_GraphicsState
*
* @Description:
* The TrueType graphics state used during bytecode interpretation.
*/
typedef struct TT_GraphicsState_
{
FT_UShort rp0;
FT_UShort rp1;
FT_UShort rp2;
FT_UnitVector dualVector;
FT_UnitVector projVector;
FT_UnitVector freeVector;
FT_Long loop;
FT_F26Dot6 minimum_distance;
FT_Int round_state;
FT_Bool auto_flip;
FT_F26Dot6 control_value_cutin;
FT_F26Dot6 single_width_cutin;
FT_F26Dot6 single_width_value;
FT_UShort delta_base;
FT_UShort delta_shift;
FT_Byte instruct_control;
/* According to Greg Hitchcock from Microsoft, the `scan_control' */
/* variable as documented in the TrueType specification is a 32-bit */
/* integer; the high-word part holds the SCANTYPE value, the low-word */
/* part the SCANCTRL value. We separate it into two fields. */
FT_Bool scan_control;
FT_Int scan_type;
FT_UShort gep0;
FT_UShort gep1;
FT_UShort gep2;
} TT_GraphicsState;
#ifdef TT_USE_BYTECODE_INTERPRETER
FT_LOCAL( void )
tt_glyphzone_done( TT_GlyphZone zone );
FT_LOCAL( FT_Error )
tt_glyphzone_new( FT_Memory memory,
FT_UShort maxPoints,
FT_Short maxContours,
TT_GlyphZone zone );
#endif /* TT_USE_BYTECODE_INTERPRETER */
/**************************************************************************
*
* EXECUTION SUBTABLES
*
* These sub-tables relate to instruction execution.
*
*/
#define TT_MAX_CODE_RANGES 3
/**************************************************************************
*
* There can only be 3 active code ranges at once:
* - the Font Program
* - the CVT Program
* - a glyph's instructions set
*/
typedef enum TT_CodeRange_Tag_
{
tt_coderange_none = 0,
tt_coderange_font,
tt_coderange_cvt,
tt_coderange_glyph
} TT_CodeRange_Tag;
typedef struct TT_CodeRange_
{
FT_Byte* base;
FT_Long size;
} TT_CodeRange;
typedef TT_CodeRange TT_CodeRangeTable[TT_MAX_CODE_RANGES];
/**************************************************************************
*
* Defines a function/instruction definition record.
*/
typedef struct TT_DefRecord_
{
FT_Int range; /* in which code range is it located? */
FT_Long start; /* where does it start? */
FT_Long end; /* where does it end? */
FT_UInt opc; /* function #, or instruction code */
FT_Bool active; /* is it active? */
FT_Bool inline_delta; /* is function that defines inline delta? */
FT_ULong sph_fdef_flags; /* flags to identify special functions */
} TT_DefRecord, *TT_DefArray;
/**************************************************************************
*
* Subglyph transformation record.
*/
typedef struct TT_Transform_
{
FT_Fixed xx, xy; /* transformation matrix coefficients */
FT_Fixed yx, yy;
FT_F26Dot6 ox, oy; /* offsets */
} TT_Transform;
/**************************************************************************
*
* A note regarding non-squared pixels:
*
* (This text will probably go into some docs at some time; for now, it
* is kept here to explain some definitions in the TT_Size_Metrics
* record).
*
* The CVT is a one-dimensional array containing values that control
* certain important characteristics in a font, like the height of all
* capitals, all lowercase letter, default spacing or stem width/height.
*
* These values are found in FUnits in the font file, and must be scaled
* to pixel coordinates before being used by the CVT and glyph programs.
* Unfortunately, when using distinct x and y resolutions (or distinct x
* and y pointsizes), there are two possible scalings.
*
* A first try was to implement a `lazy' scheme where all values were
* scaled when first used. However, while some values are always used
* in the same direction, some others are used under many different
* circumstances and orientations.
*
* I have found a simpler way to do the same, and it even seems to work
* in most of the cases:
*
* - All CVT values are scaled to the maximum ppem size.
*
* - When performing a read or write in the CVT, a ratio factor is used
* to perform adequate scaling. Example:
*
* x_ppem = 14
* y_ppem = 10
*
* We choose ppem = x_ppem = 14 as the CVT scaling size. All cvt
* entries are scaled to it.
*
* x_ratio = 1.0
* y_ratio = y_ppem/ppem (< 1.0)
*
* We compute the current ratio like:
*
* - If projVector is horizontal,
* ratio = x_ratio = 1.0
*
* - if projVector is vertical,
* ratio = y_ratio
*
* - else,
* ratio = sqrt( (proj.x * x_ratio) ^ 2 + (proj.y * y_ratio) ^ 2 )
*
* Reading a cvt value returns
* ratio * cvt[index]
*
* Writing a cvt value in pixels:
* cvt[index] / ratio
*
* The current ppem is simply
* ratio * ppem
*
*/
/**************************************************************************
*
* Metrics used by the TrueType size and context objects.
*/
typedef struct TT_Size_Metrics_
{
/* for non-square pixels */
FT_Long x_ratio;
FT_Long y_ratio;
FT_UShort ppem; /* maximum ppem size */
FT_Long ratio; /* current ratio */
FT_Fixed scale;
FT_F26Dot6 compensations[4]; /* device-specific compensations */
FT_Bool valid;
FT_Bool rotated; /* `is the glyph rotated?'-flag */
FT_Bool stretched; /* `is the glyph stretched?'-flag */
} TT_Size_Metrics;
/**************************************************************************
*
* TrueType size class.
*/
typedef struct TT_SizeRec_
{
FT_SizeRec root;
/* we have our own copy of metrics so that we can modify */
/* it without affecting auto-hinting (when used) */
FT_Size_Metrics* metrics; /* for the current rendering mode */
FT_Size_Metrics hinted_metrics; /* for the hinted rendering mode */
TT_Size_Metrics ttmetrics;
FT_ULong strike_index; /* 0xFFFFFFFF to indicate invalid */
#ifdef TT_USE_BYTECODE_INTERPRETER
FT_Long point_size; /* for the `MPS' bytecode instruction */
FT_UInt num_function_defs; /* number of function definitions */
FT_UInt max_function_defs;
TT_DefArray function_defs; /* table of function definitions */
FT_UInt num_instruction_defs; /* number of ins. definitions */
FT_UInt max_instruction_defs;
TT_DefArray instruction_defs; /* table of ins. definitions */
FT_UInt max_func;
FT_UInt max_ins;
TT_CodeRangeTable codeRangeTable;
TT_GraphicsState GS;
FT_ULong cvt_size; /* the scaled control value table */
FT_Long* cvt;
FT_UShort storage_size; /* The storage area is now part of */
FT_Long* storage; /* the instance */
TT_GlyphZoneRec twilight; /* The instance's twilight zone */
TT_ExecContext context;
/* if negative, `fpgm' (resp. `prep'), wasn't executed yet; */
/* otherwise it is the returned error code */
FT_Error bytecode_ready;
FT_Error cvt_ready;
#endif /* TT_USE_BYTECODE_INTERPRETER */
} TT_SizeRec;
/**************************************************************************
*
* TrueType driver class.
*/
typedef struct TT_DriverRec_
{
FT_DriverRec root;
TT_GlyphZoneRec zone; /* glyph loader points zone */
FT_UInt interpreter_version;
} TT_DriverRec;
/* Note: All of the functions below (except tt_size_reset()) are used */
/* as function pointers in a FT_Driver_ClassRec. Therefore their */
/* parameters are of types FT_Face, FT_Size, etc., rather than TT_Face, */
/* TT_Size, etc., so that the compiler can confirm that the types and */
/* number of parameters are correct. In all cases the FT_xxx types are */
/* cast to their TT_xxx counterparts inside the functions since FreeType */
/* will always use the TT driver to create them. */
/**************************************************************************
*
* Face functions
*/
FT_LOCAL( FT_Error )
tt_face_init( FT_Stream stream,
FT_Face ttface, /* TT_Face */
FT_Int face_index,
FT_Int num_params,
FT_Parameter* params );
FT_LOCAL( void )
tt_face_done( FT_Face ttface ); /* TT_Face */
/**************************************************************************
*
* Size functions
*/
FT_LOCAL( FT_Error )
tt_size_init( FT_Size ttsize ); /* TT_Size */
FT_LOCAL( void )
tt_size_done( FT_Size ttsize ); /* TT_Size */
#ifdef TT_USE_BYTECODE_INTERPRETER
FT_LOCAL( FT_Error )
tt_size_run_fpgm( TT_Size size,
FT_Bool pedantic );
FT_LOCAL( FT_Error )
tt_size_run_prep( TT_Size size,
FT_Bool pedantic );
FT_LOCAL( FT_Error )
tt_size_ready_bytecode( TT_Size size,
FT_Bool pedantic );
#endif /* TT_USE_BYTECODE_INTERPRETER */
FT_LOCAL( FT_Error )
tt_size_reset( TT_Size size,
FT_Bool only_height );
/**************************************************************************
*
* Driver functions
*/
FT_LOCAL( FT_Error )
tt_driver_init( FT_Module ttdriver ); /* TT_Driver */
FT_LOCAL( void )
tt_driver_done( FT_Module ttdriver ); /* TT_Driver */
/**************************************************************************
*
* Slot functions
*/
FT_LOCAL( FT_Error )
tt_slot_init( FT_GlyphSlot slot );
/* auxiliary */
#define IS_HINTED( flags ) ( ( flags & FT_LOAD_NO_HINTING ) == 0 )
FT_END_HEADER
#endif /* TTOBJS_H_ */
/* END */