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/****************************************************************************
*
* sfnt.h
*
* High-level 'sfnt' driver interface (specification).
*
* 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 SFNT_H_
#define SFNT_H_
#include <ft2build.h>
#include <freetype/internal/ftdrv.h>
#include <freetype/internal/tttypes.h>
#include <freetype/internal/wofftypes.h>
FT_BEGIN_HEADER
/**************************************************************************
*
* @functype:
* TT_Init_Face_Func
*
* @description:
* First part of the SFNT face object initialization. This finds the
* face in a SFNT file or collection, and load its format tag in
* face->format_tag.
*
* @input:
* stream ::
* The input stream.
*
* face ::
* A handle to the target face object.
*
* face_index ::
* The index of the TrueType font, if we are opening a collection, in
* bits 0-15. The numbered instance index~+~1 of a GX (sub)font, if
* applicable, in bits 16-30.
*
* num_params ::
* The number of additional parameters.
*
* params ::
* Optional additional parameters.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* The stream cursor must be at the font file's origin.
*
* This function recognizes fonts embedded in a 'TrueType collection'.
*
* Once the format tag has been validated by the font driver, it should
* then call the TT_Load_Face_Func() callback to read the rest of the
* SFNT tables in the object.
*/
typedef FT_Error
(*TT_Init_Face_Func)( FT_Stream stream,
TT_Face face,
FT_Int face_index,
FT_Int num_params,
FT_Parameter* params );
/**************************************************************************
*
* @functype:
* TT_Load_Face_Func
*
* @description:
* Second part of the SFNT face object initialization. This loads the
* common SFNT tables (head, OS/2, maxp, metrics, etc.) in the face
* object.
*
* @input:
* stream ::
* The input stream.
*
* face ::
* A handle to the target face object.
*
* face_index ::
* The index of the TrueType font, if we are opening a collection, in
* bits 0-15. The numbered instance index~+~1 of a GX (sub)font, if
* applicable, in bits 16-30.
*
* num_params ::
* The number of additional parameters.
*
* params ::
* Optional additional parameters.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* This function must be called after TT_Init_Face_Func().
*/
typedef FT_Error
(*TT_Load_Face_Func)( FT_Stream stream,
TT_Face face,
FT_Int face_index,
FT_Int num_params,
FT_Parameter* params );
/**************************************************************************
*
* @functype:
* TT_Done_Face_Func
*
* @description:
* A callback used to delete the common SFNT data from a face.
*
* @input:
* face ::
* A handle to the target face object.
*
* @note:
* This function does NOT destroy the face object.
*/
typedef void
(*TT_Done_Face_Func)( TT_Face face );
/**************************************************************************
*
* @functype:
* TT_Load_Any_Func
*
* @description:
* Load any font table into client memory.
*
* @input:
* face ::
* The face object to look for.
*
* tag ::
* The tag of table to load. Use the value 0 if you want to access the
* whole font file, else set this parameter to a valid TrueType table
* tag that you can forge with the MAKE_TT_TAG macro.
*
* offset ::
* The starting offset in the table (or the file if tag == 0).
*
* length ::
* The address of the decision variable:
*
* If `length == NULL`: Loads the whole table. Returns an error if
* 'offset' == 0!
*
* If `*length == 0`: Exits immediately; returning the length of the
* given table or of the font file, depending on the value of 'tag'.
*
* If `*length != 0`: Loads the next 'length' bytes of table or font,
* starting at offset 'offset' (in table or font too).
*
* @output:
* buffer ::
* The address of target buffer.
*
* @return:
* TrueType error code. 0 means success.
*/
typedef FT_Error
(*TT_Load_Any_Func)( TT_Face face,
FT_ULong tag,
FT_Long offset,
FT_Byte *buffer,
FT_ULong* length );
/**************************************************************************
*
* @functype:
* TT_Find_SBit_Image_Func
*
* @description:
* Check whether an embedded bitmap (an 'sbit') exists for a given glyph,
* at a given strike.
*
* @input:
* face ::
* The target face object.
*
* glyph_index ::
* The glyph index.
*
* strike_index ::
* The current strike index.
*
* @output:
* arange ::
* The SBit range containing the glyph index.
*
* astrike ::
* The SBit strike containing the glyph index.
*
* aglyph_offset ::
* The offset of the glyph data in 'EBDT' table.
*
* @return:
* FreeType error code. 0 means success. Returns
* SFNT_Err_Invalid_Argument if no sbit exists for the requested glyph.
*/
typedef FT_Error
(*TT_Find_SBit_Image_Func)( TT_Face face,
FT_UInt glyph_index,
FT_ULong strike_index,
TT_SBit_Range *arange,
TT_SBit_Strike *astrike,
FT_ULong *aglyph_offset );
/**************************************************************************
*
* @functype:
* TT_Load_SBit_Metrics_Func
*
* @description:
* Get the big metrics for a given embedded bitmap.
*
* @input:
* stream ::
* The input stream.
*
* range ::
* The SBit range containing the glyph.
*
* @output:
* big_metrics ::
* A big SBit metrics structure for the glyph.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* The stream cursor must be positioned at the glyph's offset within the
* 'EBDT' table before the call.
*
* If the image format uses variable metrics, the stream cursor is
* positioned just after the metrics header in the 'EBDT' table on
* function exit.
*/
typedef FT_Error
(*TT_Load_SBit_Metrics_Func)( FT_Stream stream,
TT_SBit_Range range,
TT_SBit_Metrics metrics );
/**************************************************************************
*
* @functype:
* TT_Load_SBit_Image_Func
*
* @description:
* Load a given glyph sbit image from the font resource. This also
* returns its metrics.
*
* @input:
* face ::
* The target face object.
*
* strike_index ::
* The strike index.
*
* glyph_index ::
* The current glyph index.
*
* load_flags ::
* The current load flags.
*
* stream ::
* The input stream.
*
* @output:
* amap ::
* The target pixmap.
*
* ametrics ::
* A big sbit metrics structure for the glyph image.
*
* @return:
* FreeType error code. 0 means success. Returns an error if no glyph
* sbit exists for the index.
*
* @note:
* The `map.buffer` field is always freed before the glyph is loaded.
*/
typedef FT_Error
(*TT_Load_SBit_Image_Func)( TT_Face face,
FT_ULong strike_index,
FT_UInt glyph_index,
FT_UInt load_flags,
FT_Stream stream,
FT_Bitmap *amap,
TT_SBit_MetricsRec *ametrics );
/**************************************************************************
*
* @functype:
* TT_Set_SBit_Strike_Func
*
* @description:
* Select an sbit strike for a given size request.
*
* @input:
* face ::
* The target face object.
*
* req ::
* The size request.
*
* @output:
* astrike_index ::
* The index of the sbit strike.
*
* @return:
* FreeType error code. 0 means success. Returns an error if no sbit
* strike exists for the selected ppem values.
*/
typedef FT_Error
(*TT_Set_SBit_Strike_Func)( TT_Face face,
FT_Size_Request req,
FT_ULong* astrike_index );
/**************************************************************************
*
* @functype:
* TT_Load_Strike_Metrics_Func
*
* @description:
* Load the metrics of a given strike.
*
* @input:
* face ::
* The target face object.
*
* strike_index ::
* The strike index.
*
* @output:
* metrics ::
* the metrics of the strike.
*
* @return:
* FreeType error code. 0 means success. Returns an error if no such
* sbit strike exists.
*/
typedef FT_Error
(*TT_Load_Strike_Metrics_Func)( TT_Face face,
FT_ULong strike_index,
FT_Size_Metrics* metrics );
/**************************************************************************
*
* @functype:
* TT_Get_PS_Name_Func
*
* @description:
* Get the PostScript glyph name of a glyph.
*
* @input:
* idx ::
* The glyph index.
*
* PSname ::
* The address of a string pointer. Will be `NULL` in case of error,
* otherwise it is a pointer to the glyph name.
*
* You must not modify the returned string!
*
* @output:
* FreeType error code. 0 means success.
*/
typedef FT_Error
(*TT_Get_PS_Name_Func)( TT_Face face,
FT_UInt idx,
FT_String** PSname );
/**************************************************************************
*
* @functype:
* TT_Load_Metrics_Func
*
* @description:
* Load a metrics table, which is a table with a horizontal and a
* vertical version.
*
* @input:
* face ::
* A handle to the target face object.
*
* stream ::
* The input stream.
*
* vertical ::
* A boolean flag. If set, load the vertical one.
*
* @return:
* FreeType error code. 0 means success.
*/
typedef FT_Error
(*TT_Load_Metrics_Func)( TT_Face face,
FT_Stream stream,
FT_Bool vertical );
/**************************************************************************
*
* @functype:
* TT_Get_Metrics_Func
*
* @description:
* Load the horizontal or vertical header in a face object.
*
* @input:
* face ::
* A handle to the target face object.
*
* vertical ::
* A boolean flag. If set, load vertical metrics.
*
* gindex ::
* The glyph index.
*
* @output:
* abearing ::
* The horizontal (or vertical) bearing. Set to zero in case of error.
*
* aadvance ::
* The horizontal (or vertical) advance. Set to zero in case of error.
*/
typedef void
(*TT_Get_Metrics_Func)( TT_Face face,
FT_Bool vertical,
FT_UInt gindex,
FT_Short* abearing,
FT_UShort* aadvance );
/**************************************************************************
*
* @functype:
* TT_Set_Palette_Func
*
* @description:
* Load the colors into `face->palette` for a given palette index.
*
* @input:
* face ::
* The target face object.
*
* idx ::
* The palette index.
*
* @return:
* FreeType error code. 0 means success.
*/
typedef FT_Error
(*TT_Set_Palette_Func)( TT_Face face,
FT_UInt idx );
/**************************************************************************
*
* @functype:
* TT_Get_Colr_Layer_Func
*
* @description:
* Iteratively get the color layer data of a given glyph index.
*
* @input:
* face ::
* The target face object.
*
* base_glyph ::
* The glyph index the colored glyph layers are associated with.
*
* @inout:
* iterator ::
* An @FT_LayerIterator object. For the first call you should set
* `iterator->p` to `NULL`. For all following calls, simply use the
* same object again.
*
* @output:
* aglyph_index ::
* The glyph index of the current layer.
*
* acolor_index ::
* The color index into the font face's color palette of the current
* layer. The value 0xFFFF is special; it doesn't reference a palette
* entry but indicates that the text foreground color should be used
* instead (to be set up by the application outside of FreeType).
*
* @return:
* Value~1 if everything is OK. If there are no more layers (or if there
* are no layers at all), value~0 gets returned. In case of an error,
* value~0 is returned also.
*/
typedef FT_Bool
(*TT_Get_Colr_Layer_Func)( TT_Face face,
FT_UInt base_glyph,
FT_UInt *aglyph_index,
FT_UInt *acolor_index,
FT_LayerIterator* iterator );
/**************************************************************************
*
* @functype:
* TT_Blend_Colr_Func
*
* @description:
* Blend the bitmap in `new_glyph` into `base_glyph` using the color
* specified by `color_index`. If `color_index` is 0xFFFF, use
* `face->foreground_color` if `face->have_foreground_color` is set.
* Otherwise check `face->palette_data.palette_flags`: If present and
* @FT_PALETTE_FOR_DARK_BACKGROUND is set, use BGRA value 0xFFFFFFFF
* (white opaque). Otherwise use BGRA value 0x000000FF (black opaque).
*
* @input:
* face ::
* The target face object.
*
* color_index ::
* Color index from the COLR table.
*
* base_glyph ::
* Slot for bitmap to be merged into. The underlying bitmap may get
* reallocated.
*
* new_glyph ::
* Slot to be incooperated into `base_glyph`.
*
* @return:
* FreeType error code. 0 means success. Returns an error if
* color_index is invalid or reallocation fails.
*/
typedef FT_Error
(*TT_Blend_Colr_Func)( TT_Face face,
FT_UInt color_index,
FT_GlyphSlot base_glyph,
FT_GlyphSlot new_glyph );
/**************************************************************************
*
* @functype:
* TT_Get_Name_Func
*
* @description:
* From the 'name' table, return a given ENGLISH name record in ASCII.
*
* @input:
* face ::
* A handle to the source face object.
*
* nameid ::
* The name id of the name record to return.
*
* @inout:
* name ::
* The address of an allocated string pointer. `NULL` if no name is
* present.
*
* @return:
* FreeType error code. 0 means success.
*/
typedef FT_Error
(*TT_Get_Name_Func)( TT_Face face,
FT_UShort nameid,
FT_String** name );
/**************************************************************************
*
* @functype:
* TT_Get_Name_ID_Func
*
* @description:
* Search whether an ENGLISH version for a given name ID is in the 'name'
* table.
*
* @input:
* face ::
* A handle to the source face object.
*
* nameid ::
* The name id of the name record to return.
*
* @output:
* win ::
* If non-negative, an index into the 'name' table with the
* corresponding (3,1) or (3,0) Windows entry.
*
* apple ::
* If non-negative, an index into the 'name' table with the
* corresponding (1,0) Apple entry.
*
* @return:
* 1 if there is either a win or apple entry (or both), 0 otheriwse.
*/
typedef FT_Bool
(*TT_Get_Name_ID_Func)( TT_Face face,
FT_UShort nameid,
FT_Int *win,
FT_Int *apple );
/**************************************************************************
*
* @functype:
* TT_Load_Table_Func
*
* @description:
* Load a given TrueType table.
*
* @input:
* face ::
* A handle to the target face object.
*
* stream ::
* The input stream.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* The function uses `face->goto_table` to seek the stream to the start
* of the table, except while loading the font directory.
*/
typedef FT_Error
(*TT_Load_Table_Func)( TT_Face face,
FT_Stream stream );
/**************************************************************************
*
* @functype:
* TT_Free_Table_Func
*
* @description:
* Free a given TrueType table.
*
* @input:
* face ::
* A handle to the target face object.
*/
typedef void
(*TT_Free_Table_Func)( TT_Face face );
/*
* @functype:
* TT_Face_GetKerningFunc
*
* @description:
* Return the horizontal kerning value between two glyphs.
*
* @input:
* face ::
* A handle to the source face object.
*
* left_glyph ::
* The left glyph index.
*
* right_glyph ::
* The right glyph index.
*
* @return:
* The kerning value in font units.
*/
typedef FT_Int
(*TT_Face_GetKerningFunc)( TT_Face face,
FT_UInt left_glyph,
FT_UInt right_glyph );
/**************************************************************************
*
* @struct:
* SFNT_Interface
*
* @description:
* This structure holds pointers to the functions used to load and free
* the basic tables that are required in a 'sfnt' font file.
*
* @fields:
* Check the various xxx_Func() descriptions for details.
*/
typedef struct SFNT_Interface_
{
TT_Loader_GotoTableFunc goto_table;
TT_Init_Face_Func init_face;
TT_Load_Face_Func load_face;
TT_Done_Face_Func done_face;
FT_Module_Requester get_interface;
TT_Load_Any_Func load_any;
/* these functions are called by `load_face' but they can also */
/* be called from external modules, if there is a need to do so */
TT_Load_Table_Func load_head;
TT_Load_Metrics_Func load_hhea;
TT_Load_Table_Func load_cmap;
TT_Load_Table_Func load_maxp;
TT_Load_Table_Func load_os2;
TT_Load_Table_Func load_post;
TT_Load_Table_Func load_name;
TT_Free_Table_Func free_name;
/* this field was called `load_kerning' up to version 2.1.10 */
TT_Load_Table_Func load_kern;
TT_Load_Table_Func load_gasp;
TT_Load_Table_Func load_pclt;
/* see `ttload.h'; this field was called `load_bitmap_header' up to */
/* version 2.1.10 */
TT_Load_Table_Func load_bhed;
TT_Load_SBit_Image_Func load_sbit_image;
/* see `ttpost.h' */
TT_Get_PS_Name_Func get_psname;
TT_Free_Table_Func free_psnames;
/* starting here, the structure differs from version 2.1.7 */
/* this field was introduced in version 2.1.8, named `get_psname' */
TT_Face_GetKerningFunc get_kerning;
/* new elements introduced after version 2.1.10 */
/* load the font directory, i.e., the offset table and */
/* the table directory */
TT_Load_Table_Func load_font_dir;
TT_Load_Metrics_Func load_hmtx;
TT_Load_Table_Func load_eblc;
TT_Free_Table_Func free_eblc;
TT_Set_SBit_Strike_Func set_sbit_strike;
TT_Load_Strike_Metrics_Func load_strike_metrics;
TT_Load_Table_Func load_cpal;
TT_Load_Table_Func load_colr;
TT_Free_Table_Func free_cpal;
TT_Free_Table_Func free_colr;
TT_Set_Palette_Func set_palette;
TT_Get_Colr_Layer_Func get_colr_layer;
TT_Blend_Colr_Func colr_blend;
TT_Get_Metrics_Func get_metrics;
TT_Get_Name_Func get_name;
TT_Get_Name_ID_Func get_name_id;
} SFNT_Interface;
/* transitional */
typedef SFNT_Interface* SFNT_Service;
#define FT_DEFINE_SFNT_INTERFACE( \
class_, \
goto_table_, \
init_face_, \
load_face_, \
done_face_, \
get_interface_, \
load_any_, \
load_head_, \
load_hhea_, \
load_cmap_, \
load_maxp_, \
load_os2_, \
load_post_, \
load_name_, \
free_name_, \
load_kern_, \
load_gasp_, \
load_pclt_, \
load_bhed_, \
load_sbit_image_, \
get_psname_, \
free_psnames_, \
get_kerning_, \
load_font_dir_, \
load_hmtx_, \
load_eblc_, \
free_eblc_, \
set_sbit_strike_, \
load_strike_metrics_, \
load_cpal_, \
load_colr_, \
free_cpal_, \
free_colr_, \
set_palette_, \
get_colr_layer_, \
colr_blend_, \
get_metrics_, \
get_name_, \
get_name_id_ ) \
static const SFNT_Interface class_ = \
{ \
goto_table_, \
init_face_, \
load_face_, \
done_face_, \
get_interface_, \
load_any_, \
load_head_, \
load_hhea_, \
load_cmap_, \
load_maxp_, \
load_os2_, \
load_post_, \
load_name_, \
free_name_, \
load_kern_, \
load_gasp_, \
load_pclt_, \
load_bhed_, \
load_sbit_image_, \
get_psname_, \
free_psnames_, \
get_kerning_, \
load_font_dir_, \
load_hmtx_, \
load_eblc_, \
free_eblc_, \
set_sbit_strike_, \
load_strike_metrics_, \
load_cpal_, \
load_colr_, \
free_cpal_, \
free_colr_, \
set_palette_, \
get_colr_layer_, \
colr_blend_, \
get_metrics_, \
get_name_, \
get_name_id_ \
};
FT_END_HEADER
#endif /* SFNT_H_ */
/* END */