firefox-main/modules/freetype2/src/base/ftadvanc.c (file symbol)

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/****************************************************************************
*
* ftadvanc.c
*
* Quick computation of advance widths (body).
*
* Copyright (C) 2008-2026 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 <freetype/internal/ftdebug.h>
#include <freetype/ftadvanc.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftcalc.h>
static FT_Error
ft_face_scale_advances_( FT_Face face,
FT_Fixed* advances,
FT_UInt count,
FT_Int32 flags )
{
FT_Fixed scale;
FT_UInt nn;
if ( flags & FT_LOAD_NO_SCALE )
return FT_Err_Ok;
if ( !face->size )
return FT_THROW( Invalid_Size_Handle );
if ( flags & FT_LOAD_VERTICAL_LAYOUT )
scale = face->size->metrics.y_scale;
else
scale = face->size->metrics.x_scale;
/* this must be the same scaling as to get linear{Hori,Vert}Advance */
/* (see `FT_Load_Glyph' implementation in src/base/ftobjs.c) */
for ( nn = 0; nn < count; nn++ )
advances[nn] = FT_MulFix( 1024 * advances[nn], scale );
return FT_Err_Ok;
}
/* loading (and hinting) to calculate the advances is slow */
/* unless TrueType hdmx table is provided as an accelerator */
static FT_Error
ft_load_advances( FT_Face face,
FT_UInt gindex,
FT_UInt count,
FT_Int32 flags,
FT_Fixed *padvances )
{
FT_UInt nn;
FT_Error error = FT_Err_Ok;
FT_Pos factor = flags & FT_LOAD_NO_SCALE ? 1 : 1024;
FT_Pos* advance = flags & FT_LOAD_VERTICAL_LAYOUT
? &face->glyph->advance.y
: &face->glyph->advance.x;
flags |= (FT_UInt32)FT_LOAD_ADVANCE_ONLY;
for ( nn = 0; nn < count; nn++ )
{
error = FT_Load_Glyph( face, gindex + nn, flags );
if ( error )
break;
/* scale from 26.6 to 16.16, unless NO_SCALE was requested */
padvances[nn] = *advance * factor;
}
return error;
}
/* at the moment, we can perform fast advance retrieval only in */
/* the following cases: */
/* */
/* - unscaled load */
/* - unhinted load */
/* - light-hinted load */
/* - if a variations font, it must have an `HVAR' or `VVAR' */
/* table (thus the old MM or GX fonts don't qualify; this */
/* gets checked by the driver-specific functions) */
#define LOAD_ADVANCE_FAST_CHECK( face, flags ) \
( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING ) || \
FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT )
/* documentation is in ftadvanc.h */
FT_EXPORT_DEF( FT_Error )
FT_Get_Advance( FT_Face face,
FT_UInt gindex,
FT_Int32 flags,
FT_Fixed *padvance )
{
FT_Face_GetAdvancesFunc func;
if ( !face )
return FT_THROW( Invalid_Face_Handle );
if ( !padvance )
return FT_THROW( Invalid_Argument );
if ( gindex >= (FT_UInt)face->num_glyphs )
return FT_THROW( Invalid_Glyph_Index );
func = face->driver->clazz->get_advances;
if ( func && LOAD_ADVANCE_FAST_CHECK( face, flags ) )
{
FT_Error error;
error = func( face, gindex, 1, flags, padvance );
if ( !error )
return ft_face_scale_advances_( face, padvance, 1, flags );
if ( FT_ERR_NEQ( error, Unimplemented_Feature ) )
return error;
}
if ( flags & FT_ADVANCE_FLAG_FAST_ONLY )
return FT_THROW( Unimplemented_Feature );
return ft_load_advances( face, gindex, 1, flags, padvance );
}
/* documentation is in ftadvanc.h */
FT_EXPORT_DEF( FT_Error )
FT_Get_Advances( FT_Face face,
FT_UInt start,
FT_UInt count,
FT_Int32 flags,
FT_Fixed *padvances )
{
FT_Face_GetAdvancesFunc func;
FT_UInt num, end;
if ( !face )
return FT_THROW( Invalid_Face_Handle );
if ( !padvances )
return FT_THROW( Invalid_Argument );
num = (FT_UInt)face->num_glyphs;
end = start + count;
if ( start >= num || end < start || end > num )
return FT_THROW( Invalid_Glyph_Index );
if ( count == 0 )
return FT_Err_Ok;
func = face->driver->clazz->get_advances;
if ( func && LOAD_ADVANCE_FAST_CHECK( face, flags ) )
{
FT_Error error;
error = func( face, start, count, flags, padvances );
if ( !error )
return ft_face_scale_advances_( face, padvances, count, flags );
if ( FT_ERR_NEQ( error, Unimplemented_Feature ) )
return error;
}
if ( flags & FT_ADVANCE_FLAG_FAST_ONLY )
return FT_THROW( Unimplemented_Feature );
return ft_load_advances( face, start, count, flags, padvances );
}
/* END */