[autofit] Add code for reverse charmaps and adjustment database lookup.

* src/autofit/aftypes.h (AF_ReverseMapEntry, AF_ReverseCharacterMap): New
structures.

* src/autofit/afadjust.c (af_adjustment_database_lookup,
af_reverse_character_map_entry_compare, af_reverse_character_map_lookup,
af_lookup_vertical_separation_type, af_lookup_tilde_correction_type,
af_reverse_character_map_expand, af_reverse_character_map_new,
af_reverse_character_map_done): New functions.

* src/autofit/afadjust.c: Updated.
This commit is contained in:
Craig White 2024-01-28 17:35:15 +01:00 committed by Werner Lemberg
parent fe31700701
commit c70b3d9484
3 changed files with 294 additions and 0 deletions

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@ -182,4 +182,257 @@
};
/* Helper function: get the adjustment database entry for a codepoint. */
static const AF_AdjustmentDatabaseEntry*
af_adjustment_database_lookup( FT_UInt32 codepoint )
{
/* Binary search for database entry */
FT_Int low = 0;
FT_Int high = AF_ADJUSTMENT_DATABASE_LENGTH - 1;
while ( high >= low )
{
FT_Int mid = ( low + high ) / 2;
FT_UInt32 mid_codepoint = adjustment_database[mid].codepoint;
if ( mid_codepoint < codepoint )
low = mid + 1;
else if ( mid_codepoint > codepoint )
high = mid - 1;
else
return &adjustment_database[mid];
}
return NULL;
}
/* `qsort` compare function for reverse character map. */
FT_COMPARE_DEF( FT_Int )
af_reverse_character_map_entry_compare( const void *a,
const void *b )
{
const AF_ReverseMapEntry entry_a = *((const AF_ReverseMapEntry *)a);
const AF_ReverseMapEntry entry_b = *((const AF_ReverseMapEntry *)b);
return entry_a.glyph_index < entry_b.glyph_index
? -1
: entry_a.glyph_index > entry_b.glyph_index
? 1
: 0;
}
static FT_UInt32
af_reverse_character_map_lookup( AF_ReverseCharacterMap map,
FT_Int glyph_index )
{
FT_Int low, high;
FT_Long length;
if ( !map )
return 0;
length = map->length;
/* Binary search for reverse character map entry. */
low = 0;
high = length - 1;
while ( high >= low )
{
FT_Int mid = ( high + low ) / 2;
FT_Int mid_glyph_index = map->entries[mid].glyph_index;
if ( glyph_index < mid_glyph_index )
high = mid - 1;
else if ( glyph_index > mid_glyph_index )
low = mid + 1;
else
return map->entries[mid].codepoint;
}
return 0;
}
FT_LOCAL_DEF( AF_VerticalSeparationAdjustmentType )
af_lookup_vertical_separation_type( AF_ReverseCharacterMap map,
FT_Int glyph_index )
{
FT_UInt32 codepoint = af_reverse_character_map_lookup( map,
glyph_index );
const AF_AdjustmentDatabaseEntry *entry =
af_adjustment_database_lookup( codepoint );
if ( !entry )
return AF_VERTICAL_ADJUSTMENT_NONE;
return entry->vertical_separation_adjustment_type;
}
/* Return 1 if tilde correction should be applied to the topmost */
/* contour, else 0. */
FT_LOCAL_DEF( FT_Bool )
af_lookup_tilde_correction_type( AF_ReverseCharacterMap map,
FT_Int glyph_index )
{
FT_UInt32 codepoint = af_reverse_character_map_lookup( map,
glyph_index );
const AF_AdjustmentDatabaseEntry *entry =
af_adjustment_database_lookup( codepoint );
if ( !entry )
return 0;
return entry->apply_tilde;
}
/* Prepare to add one more entry to the reverse character map. */
/* This is a helper function for `af_reverse_character_map_new`. */
static FT_Error
af_reverse_character_map_expand( AF_ReverseCharacterMap map,
FT_Long *capacity,
FT_Memory memory )
{
FT_Error error;
if ( map->length < *capacity )
return FT_Err_Ok;
if ( map->length == *capacity )
{
FT_Long new_capacity = *capacity + *capacity / 2;
if ( FT_RENEW_ARRAY( map->entries, map->length, new_capacity ) )
return error;
*capacity = new_capacity;
}
return FT_Err_Ok;
}
FT_LOCAL_DEF( FT_Error )
af_reverse_character_map_new( AF_ReverseCharacterMap *map,
AF_FaceGlobals globals )
{
FT_Error error;
FT_Face face = globals->face;
FT_Memory memory = face->memory;
FT_CharMap old_charmap;
FT_Long capacity;
/* Search for a unicode charmap. */
/* If there isn't one, create a blank map. */
FT_TRACE4(( "af_reverse_character_map_new:"
" building reverse character map\n" ));
/* Back up `face->charmap` because `find_unicode_charmap` sets it. */
old_charmap = face->charmap;
if ( ( error = find_unicode_charmap( face ) ) )
goto Exit;
*map = NULL;
if ( FT_NEW( *map ) )
goto Exit;
/* Start with a capacity of 10 entries. */
capacity = 10;
( *map )->length = 0;
if ( FT_NEW_ARRAY( ( *map )->entries, capacity ) )
goto Exit;
{
FT_UInt i;
#ifdef FT_DEBUG_LEVEL_TRACE
int failed_lookups = 0;
#endif
for ( i = 0; i < AF_ADJUSTMENT_DATABASE_LENGTH; i++ )
{
FT_UInt32 codepoint = adjustment_database[i].codepoint;
FT_Int glyph = FT_Get_Char_Index( face, codepoint );
if ( glyph == 0 )
{
#ifdef FT_DEBUG_LEVEL_TRACE
failed_lookups++;
#endif
continue;
}
error = af_reverse_character_map_expand( *map, &capacity, memory );
if ( error )
goto Exit;
( *map )->length++;
( *map )->entries[i].glyph_index = glyph;
( *map )->entries[i].codepoint = codepoint;
}
}
ft_qsort( ( *map )->entries,
( *map )->length,
sizeof ( AF_ReverseMapEntry ),
af_reverse_character_map_entry_compare );
FT_TRACE4(( " reverse character map built successfully"
" with %ld entries\n", (*map)->length ));
Exit:
face->charmap = old_charmap;
if ( error )
{
FT_TRACE4(( " error while building reverse character map."
" Using blank map.\n" ));
if ( *map )
FT_FREE( ( *map )->entries );
FT_FREE( *map );
*map = NULL;
return error;
}
return FT_Err_Ok;
}
FT_LOCAL_DEF( FT_Error )
af_reverse_character_map_done( AF_ReverseCharacterMap map,
FT_Memory memory )
{
if ( map )
FT_FREE( map->entries );
FT_FREE( map );
return FT_Err_Ok;
}
/* END */

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@ -58,6 +58,26 @@ FT_BEGIN_HEADER
} AF_AdjustmentDatabaseEntry;
FT_LOCAL( AF_VerticalSeparationAdjustmentType )
af_lookup_vertical_separation_type( AF_ReverseCharacterMap map,
FT_Int glyph_index );
FT_LOCAL( FT_Bool )
af_lookup_tilde_correction_type( AF_ReverseCharacterMap map,
FT_Int glyph_index );
/* Allocate and populate the reverse character map, */
/* using the character map within the face. */
FT_LOCAL( FT_Error )
af_reverse_character_map_new( AF_ReverseCharacterMap *map,
AF_FaceGlobals globals );
/* Free the reverse character map. */
FT_LOCAL( FT_Error )
af_reverse_character_map_done( AF_ReverseCharacterMap map,
FT_Memory memory );
FT_END_HEADER
#endif /* AFADJUST_H_ */

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@ -406,6 +406,27 @@ extern void* af_debug_hints_;
typedef struct AF_FaceGlobalsRec_* AF_FaceGlobals;
/* Store a mapping from glyphs to unicode codepoints. */
/* See `afadjust.c` for details. */
typedef struct AF_ReverseMapEntry_
{
FT_Int glyph_index;
FT_UInt32 codepoint;
} AF_ReverseMapEntry;
typedef struct AF_ReverseCharacterMapRec_
{
FT_Long length;
AF_ReverseMapEntry *entries;
} AF_ReverseCharacterMapRec;
typedef struct AF_ReverseCharacterMapRec_* AF_ReverseCharacterMap;
/* This is the main structure that combines everything. Autofit modules */
/* specific to writing systems derive their structures from it, for */
/* example `AF_LatinMetrics'. */