ref: b7b163cb077edd6b6355dd465cc9dc1d4d4d7b53
dir: /src/truetype/ttdriver.c/
/***************************************************************************/
/* */
/* ttdriver.c */
/* */
/* TrueType font driver implementation (body). */
/* */
/* Copyright 1996-2001 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. */
/* */
/***************************************************************************/
#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_SFNT_H
#include FT_TRUETYPE_IDS_H
#include "ttdriver.h"
#include "ttgload.h"
#include "tterrors.h"
/*************************************************************************/
/* */
/* The macro FT_COMPONENT is used in trace mode. It is an implicit */
/* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */
/* messages during execution. */
/* */
#undef FT_COMPONENT
#define FT_COMPONENT trace_ttdriver
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** ****/
/**** F A C E S ****/
/**** ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
#undef PAIR_TAG
#define PAIR_TAG( left, right ) ( ( (FT_ULong)left << 16 ) | \
(FT_ULong)right )
/*************************************************************************/
/* */
/* <Function> */
/* Get_Kerning */
/* */
/* <Description> */
/* A driver method used to return the kerning vector between two */
/* glyphs of the same face. */
/* */
/* <Input> */
/* face :: A handle to the 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. */
/* */
/* <Output> */
/* kerning :: The kerning vector. This is in font units 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 function. Other layouts, or more sophisticated */
/* kernings, are out of scope of this method (the basic driver */
/* interface is meant to be simple). */
/* */
/* They can be implemented by format-specific interfaces. */
/* */
static FT_Error
Get_Kerning( TT_Face face,
FT_UInt left_glyph,
FT_UInt right_glyph,
FT_Vector* kerning )
{
TT_Kern0_Pair pair;
if ( !face )
return TT_Err_Invalid_Face_Handle;
kerning->x = 0;
kerning->y = 0;
if ( face->kern_pairs )
{
/* there are some kerning pairs in this font file! */
FT_ULong search_tag = PAIR_TAG( left_glyph, right_glyph );
FT_Long left, right;
left = 0;
right = face->num_kern_pairs - 1;
while ( left <= right )
{
FT_Int middle = left + ( ( right - left ) >> 1 );
FT_ULong cur_pair;
pair = face->kern_pairs + middle;
cur_pair = PAIR_TAG( pair->left, pair->right );
if ( cur_pair == search_tag )
goto Found;
if ( cur_pair < search_tag )
left = middle + 1;
else
right = middle - 1;
}
}
Exit:
return TT_Err_Ok;
Found:
kerning->x = pair->value;
goto Exit;
}
#undef PAIR_TAG
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** ****/
/**** S I Z E S ****/
/**** ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/* */
/* <Function> */
/* Set_Char_Sizes */
/* */
/* <Description> */
/* A driver method used to reset a size's character sizes (horizontal */
/* and vertical) expressed in fractional points. */
/* */
/* <Input> */
/* char_width :: The character width expressed in 26.6 */
/* fractional points. */
/* */
/* char_height :: The character height expressed in 26.6 */
/* fractional points. */
/* */
/* horz_resolution :: The horizontal resolution of the output device. */
/* */
/* vert_resolution :: The vertical resolution of the output device. */
/* */
/* <InOut> */
/* size :: A handle to the target size object. */
/* */
/* <Return> */
/* FreeType error code. 0 means success. */
/* */
static FT_Error
Set_Char_Sizes( TT_Size size,
FT_F26Dot6 char_width,
FT_F26Dot6 char_height,
FT_UInt horz_resolution,
FT_UInt vert_resolution )
{
FT_Size_Metrics* metrics = &size->root.metrics;
TT_Face face = (TT_Face)size->root.face;
FT_Long dim_x, dim_y;
/* This bit flag, when set, indicates that the pixel size must be */
/* truncated to an integer. Nearly all TrueType fonts have this */
/* bit set, as hinting won't work really well otherwise. */
/* */
/* However, for those rare fonts who do not set it, we override */
/* the default computations performed by the base layer. I */
/* really don't know whether this is useful, but hey, that's the */
/* spec :-) */
/* */
if ( ( face->header.Flags & 8 ) == 0 )
{
/* Compute pixel sizes in 26.6 units */
dim_x = ( char_width * horz_resolution + 36 ) / 72;
dim_y = ( char_height * vert_resolution + 36 ) / 72;
metrics->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
metrics->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );
metrics->x_ppem = (FT_UShort)( dim_x >> 6 );
metrics->y_ppem = (FT_UShort)( dim_y >> 6 );
}
size->ttmetrics.valid = FALSE;
#ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
size->strike_index = 0xFFFF;
#endif
return TT_Size_Reset( size );
}
/*************************************************************************/
/* */
/* <Function> */
/* Set_Pixel_Sizes */
/* */
/* <Description> */
/* A driver method used to reset a size's character sizes (horizontal */
/* and vertical) expressed in integer pixels. */
/* */
/* <Input> */
/* pixel_width :: The character width expressed in integer pixels. */
/* */
/* pixel_height :: The character height expressed in integer pixels. */
/* */
/* <InOut> */
/* size :: A handle to the target size object. */
/* */
/* <Return> */
/* FreeType error code. 0 means success. */
/* */
static FT_Error
Set_Pixel_Sizes( TT_Size size,
FT_UInt pixel_width,
FT_UInt pixel_height )
{
FT_UNUSED( pixel_width );
FT_UNUSED( pixel_height );
/* many things have been pre-computed by the base layer */
size->ttmetrics.valid = FALSE;
#ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
size->strike_index = 0xFFFF;
#endif
return TT_Size_Reset( size );
}
/*************************************************************************/
/* */
/* <Function> */
/* Load_Glyph */
/* */
/* <Description> */
/* A driver method used to load a glyph within a given glyph slot. */
/* */
/* <Input> */
/* slot :: A handle to the target slot object where the glyph */
/* will be loaded. */
/* */
/* size :: A handle to the source face size at which the glyph */
/* must be scaled, loaded, etc. */
/* */
/* glyph_index :: The index of the glyph in the font file. */
/* */
/* load_flags :: A flag indicating what to load for this glyph. The */
/* FTLOAD_??? 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. */
/* */
static FT_Error
Load_Glyph( TT_GlyphSlot slot,
TT_Size size,
FT_UShort glyph_index,
FT_UInt load_flags )
{
FT_Error error;
if ( !slot )
return TT_Err_Invalid_Slot_Handle;
/* check whether we want a scaled outline or bitmap */
if ( !size )
load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING;
if ( load_flags & FT_LOAD_NO_SCALE )
size = NULL;
/* reset the size object if necessary */
if ( size )
{
/* these two object must have the same parent */
if ( size->root.face != slot->face )
return TT_Err_Invalid_Face_Handle;
if ( !size->ttmetrics.valid )
{
if ( FT_SET_ERROR( TT_Size_Reset( size ) ) )
return error;
}
}
/* now load the glyph outline if necessary */
error = TT_Load_Glyph( size, slot, glyph_index, load_flags );
/* force drop-out mode to 2 - irrelevant now */
/* slot->outline.dropout_mode = 2; */
return error;
}
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** ****/
/**** C H A R A C T E R M A P P I N G S ****/
/**** ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/* */
/* <Function> */
/* Get_Char_Index */
/* */
/* <Description> */
/* Uses a charmap to return a given character code's glyph index. */
/* */
/* <Input> */
/* charmap :: A handle to the source charmap object. */
/* charcode :: The character code. */
/* */
/* <Return> */
/* Glyph index. 0 means `undefined character code'. */
/* */
static FT_UInt
Get_Char_Index( TT_CharMap charmap,
FT_Long charcode )
{
FT_Error error;
TT_Face face;
TT_CMapTable cmap;
cmap = &charmap->cmap;
face = (TT_Face)charmap->root.face;
/* Load table if needed */
if ( !cmap->loaded )
{
SFNT_Service sfnt = (SFNT_Service)face->sfnt;
error = sfnt->load_charmap( face, cmap, face->root.stream );
if ( error )
return 0;
cmap->loaded = TRUE;
}
if ( cmap->get_index )
return cmap->get_index( cmap, charcode );
else
return 0;
}
/*************************************************************************/
/* */
/* <Function> */
/* Get_Next_Char */
/* */
/* <Description> */
/* Uses a charmap to return the next encoded char. */
/* */
/* <Input> */
/* charmap :: A handle to the source charmap object. */
/* charcode :: The character code. */
/* */
/* <Return> */
/* Next char code. 0 means `no more encoded characters'. */
/* */
static FT_UInt
Get_Next_Char( TT_CharMap charmap,
FT_Long charcode )
{
FT_Error error;
TT_Face face;
TT_CMapTable cmap;
cmap = &charmap->cmap;
face = (TT_Face)charmap->root.face;
/* Load table if needed */
if ( !cmap->loaded )
{
SFNT_Service sfnt = (SFNT_Service)face->sfnt;
error = sfnt->load_charmap( face, cmap, face->root.stream );
if ( error )
return 0;
cmap->loaded = TRUE;
}
if ( cmap->get_next_char )
return cmap->get_next_char ( cmap, charcode );
else
return 0;
}
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** ****/
/**** D R I V E R I N T E R F A C E ****/
/**** ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
static FT_Module_Interface
tt_get_interface( TT_Driver driver,
const char* interface )
{
FT_Module sfntd = FT_Get_Module( driver->root.root.library,
"sfnt" );
SFNT_Service sfnt;
/* only return the default interface from the SFNT module */
if ( sfntd )
{
sfnt = (SFNT_Service)( sfntd->clazz->module_interface );
if ( sfnt )
return sfnt->get_interface( FT_MODULE( driver ), interface );
}
return 0;
}
/* The FT_DriverInterface structure is defined in ftdriver.h. */
FT_CALLBACK_TABLE_DEF
const FT_Driver_ClassRec tt_driver_class =
{
{
ft_module_font_driver |
ft_module_driver_scalable |
#ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER
ft_module_driver_has_hinter,
#else
0,
#endif
sizeof ( TT_DriverRec ),
"truetype", /* driver name */
0x10000L, /* driver version == 1.0 */
0x20000L, /* driver requires FreeType 2.0 or above */
(void*)0, /* driver specific interface */
(FT_Module_Constructor)TT_Driver_Init,
(FT_Module_Destructor) TT_Driver_Done,
(FT_Module_Requester) tt_get_interface,
},
sizeof ( TT_FaceRec ),
sizeof ( TT_SizeRec ),
sizeof ( FT_GlyphSlotRec ),
(FT_Face_InitFunc) TT_Face_Init,
(FT_Face_DoneFunc) TT_Face_Done,
(FT_Size_InitFunc) TT_Size_Init,
(FT_Size_DoneFunc) TT_Size_Done,
(FT_Slot_InitFunc)0,
(FT_Slot_DoneFunc)0,
(FT_Size_ResetPointsFunc) Set_Char_Sizes,
(FT_Size_ResetPixelsFunc)Set_Pixel_Sizes,
(FT_Slot_LoadFunc) Load_Glyph,
(FT_CharMap_CharIndexFunc) Get_Char_Index,
(FT_Face_GetKerningFunc) Get_Kerning,
(FT_Face_AttachFunc) 0,
(FT_Face_GetAdvancesFunc) 0,
(FT_CharMap_CharNextFunc) Get_Next_Char
};
#ifdef FT_CONFIG_OPTION_DYNAMIC_DRIVERS
/*************************************************************************/
/* */
/* <Function> */
/* getDriverClass */
/* */
/* <Description> */
/* This function is used when compiling the TrueType driver as a */
/* shared library (`.DLL' or `.so'). It will be used by the */
/* high-level library of FreeType to retrieve the address of the */
/* driver's generic interface. */
/* */
/* It shouldn't be implemented in a static build, as each driver must */
/* have the same function as an exported entry point. */
/* */
/* <Return> */
/* The address of the TrueType's driver generic interface. The */
/* format-specific interface can then be retrieved through the method */
/* interface->get_format_interface. */
/* */
FT_EXPORT_DEF( const FT_Driver_Class )
getDriverClass( void )
{
return &tt_driver_class;
}
#endif /* CONFIG_OPTION_DYNAMIC_DRIVERS */
/* END */