@ -28,9 +28,16 @@
# include "hb-ot-shape-private.hh"
# ifndef HB_DEBUG_ARABIC
# define HB_DEBUG_ARABIC (HB_DEBUG+0)
# endif
/* buffer var allocations */
# define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */
# define HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH HB_BUFFER_SCRATCH_FLAG_COMPLEX0
/*
* Joining types :
@ -84,7 +91,7 @@ static const hb_tag_t arabic_features[] =
/* Same order as the feature array */
enum {
enum arabic_action_t {
ISOL ,
FINA ,
FIN2 ,
@ -95,7 +102,11 @@ enum {
NONE ,
ARABIC_NUM_FEATURES = NONE
ARABIC_NUM_FEATURES = NONE ,
/* We abuse the same byte for other things... */
STCH_FIXED ,
STCH_REPEATING ,
} ;
static const struct arabic_state_table_entry {
@ -139,6 +150,11 @@ arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
hb_font_t * font ,
hb_buffer_t * buffer ) ;
static void
record_stch ( const hb_ot_shape_plan_t * plan ,
hb_font_t * font ,
hb_buffer_t * buffer ) ;
static void
collect_features_arabic ( hb_ot_shape_planner_t * plan )
{
@ -165,6 +181,9 @@ collect_features_arabic (hb_ot_shape_planner_t *plan)
map - > add_gsub_pause ( nuke_joiners ) ;
map - > add_global_bool_feature ( HB_TAG ( ' s ' , ' t ' , ' c ' , ' h ' ) ) ;
map - > add_gsub_pause ( record_stch ) ;
map - > add_global_bool_feature ( HB_TAG ( ' c ' , ' c ' , ' m ' , ' p ' ) ) ;
map - > add_global_bool_feature ( HB_TAG ( ' l ' , ' o ' , ' c ' , ' l ' ) ) ;
@ -208,8 +227,10 @@ struct arabic_shape_plan_t
* mask_array [ NONE ] = = 0. */
hb_mask_t mask_array [ ARABIC_NUM_FEATURES + 1 ] ;
bool do_fallback ;
arabic_fallback_plan_t * fallback_plan ;
unsigned int do_fallback : 1 ;
unsigned int has_stch : 1 ;
} ;
void *
@ -220,6 +241,7 @@ data_create_arabic (const hb_ot_shape_plan_t *plan)
return NULL ;
arabic_plan - > do_fallback = plan - > props . script = = HB_SCRIPT_ARABIC ;
arabic_plan - > has_stch = ! ! plan - > map . get_1_mask ( HB_TAG ( ' s ' , ' t ' , ' c ' , ' h ' ) ) ;
for ( unsigned int i = 0 ; i < ARABIC_NUM_FEATURES ; i + + ) {
arabic_plan - > mask_array [ i ] = plan - > map . get_1_mask ( arabic_features [ i ] ) ;
arabic_plan - > do_fallback = arabic_plan - > do_fallback & &
@ -320,8 +342,6 @@ setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,
hb_glyph_info_t * info = buffer - > info ;
for ( unsigned int i = 0 ; i < count ; i + + )
info [ i ] . mask | = arabic_plan - > mask_array [ info [ i ] . arabic_shaping_action ( ) ] ;
HB_BUFFER_DEALLOCATE_VAR ( buffer , arabic_shaping_action ) ;
}
static void
@ -371,6 +391,193 @@ retry:
arabic_fallback_plan_shape ( fallback_plan , font , buffer ) ;
}
/*
* Stretch feature : " stch " .
* See example here :
* https : //www.microsoft.com/typography/OpenTypeDev/syriac/intro.htm
* We implement this in a generic way , such that the Arabic subtending
* marks can use it as well .
*/
static void
record_stch ( const hb_ot_shape_plan_t * plan ,
hb_font_t * font ,
hb_buffer_t * buffer )
{
const arabic_shape_plan_t * arabic_plan = ( const arabic_shape_plan_t * ) plan - > data ;
if ( ! arabic_plan - > has_stch )
return ;
/* 'stch' feature was just applied. Look for anything that multiplied,
* and record it for stch treatment later . Note that rtlm , frac , etc
* are applied before stch , but we assume that they didn ' t result in
* anything multiplying into 5 pieces , so it ' s safe - ish . . . */
unsigned int count = buffer - > len ;
hb_glyph_info_t * info = buffer - > info ;
for ( unsigned int i = 0 ; i < count ; i + + )
if ( unlikely ( _hb_glyph_info_multiplied ( & info [ i ] ) ) )
{
unsigned int comp = _hb_glyph_info_get_lig_comp ( & info [ i ] ) ;
info [ i ] . arabic_shaping_action ( ) = comp % 2 ? STCH_REPEATING : STCH_FIXED ;
buffer - > scratch_flags | = HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH ;
}
}
static void
apply_stch ( const hb_ot_shape_plan_t * plan ,
hb_buffer_t * buffer ,
hb_font_t * font )
{
if ( likely ( ! ( buffer - > scratch_flags & HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH ) ) )
return ;
/* The Arabic shaper currently always processes in RTL mode, so we should
* stretch / position the stretched pieces to the left / preceding glyphs . */
/* We do a two pass implementation:
* First pass calculates the exact number of extra glyphs we need ,
* We then enlarge buffer to have that much room ,
* Second pass applies the stretch , copying things to the end of buffer .
*/
/* 30 = 2048 / 70.
* https : //www.microsoft.com/typography/cursivescriptguidelines.mspx */
hb_position_t overlap = font - > x_scale / 30 ;
DEBUG_MSG ( ARABIC , NULL , " overlap for stretching is %d " , overlap ) ;
int sign = font - > x_scale < 0 ? - 1 : + 1 ;
unsigned int extra_glyphs_needed = 0 ; // Set during MEASURE, used during CUT
for ( enum step_t { MEASURE , CUT } step = MEASURE ; step < = CUT ; step = ( step_t ) ( step + 1 ) )
{
unsigned int count = buffer - > len ;
hb_glyph_info_t * info = buffer - > info ;
hb_glyph_position_t * pos = buffer - > pos ;
unsigned int new_len = count + extra_glyphs_needed ; // write head during CUT
unsigned int j = new_len ;
for ( unsigned int i = count ; i ; i - - )
{
if ( ! hb_in_range < unsigned > ( info [ i - 1 ] . arabic_shaping_action ( ) , STCH_FIXED , STCH_REPEATING ) )
{
if ( step = = CUT )
{
- - j ;
info [ j ] = info [ i - 1 ] ;
pos [ j ] = pos [ i - 1 ] ;
}
continue ;
}
/* Yay, justification! */
hb_position_t w_total = 0 ; // Total to be filled
hb_position_t w_fixed = 0 ; // Sum of fixed tiles
hb_position_t w_repeating = 0 ; // Sum of repeating tiles
int n_fixed = 0 ;
int n_repeating = 0 ;
unsigned int end = i ;
while ( i & &
hb_in_range < unsigned > ( info [ i - 1 ] . arabic_shaping_action ( ) , STCH_FIXED , STCH_REPEATING ) )
{
i - - ;
hb_glyph_extents_t extents ;
if ( ! font - > get_glyph_extents ( info [ i ] . codepoint , & extents ) )
extents . width = 0 ;
extents . width - = overlap ;
if ( info [ i ] . arabic_shaping_action ( ) = = STCH_FIXED )
{
w_fixed + = extents . width ;
n_fixed + + ;
}
else
{
w_repeating + = extents . width ;
n_repeating + + ;
}
}
unsigned int start = i ;
unsigned int context = i ;
while ( context & &
! hb_in_range < unsigned > ( info [ context - 1 ] . arabic_shaping_action ( ) , STCH_FIXED , STCH_REPEATING ) & &
( _hb_glyph_info_is_default_ignorable ( & info [ context - 1 ] ) | |
HB_UNICODE_GENERAL_CATEGORY_IS_WORD ( _hb_glyph_info_get_general_category ( & info [ context - 1 ] ) ) ) )
{
context - - ;
w_total + = pos [ context ] . x_advance ;
}
i + + ; // Don't touch i again.
DEBUG_MSG ( ARABIC , NULL , " %s stretch at (%d,%d,%d) " ,
step = = MEASURE ? " measuring " : " cutting " , context , start , end ) ;
DEBUG_MSG ( ARABIC , NULL , " rest of word: count=%d width %d " , start - context , w_total ) ;
DEBUG_MSG ( ARABIC , NULL , " fixed tiles: count=%d width=%d " , n_fixed , w_fixed ) ;
DEBUG_MSG ( ARABIC , NULL , " repeating tiles: count=%d width=%d " , n_repeating , w_repeating ) ;
/* Number of additional times to repeat each repeating tile. */
int n_copies = 0 ;
hb_position_t w_remaining = w_total - w_fixed - overlap ;
if ( sign * w_remaining > sign * w_repeating & & sign * w_repeating > 0 )
n_copies = ( sign * w_remaining + sign * w_repeating / 2 ) / ( sign * w_repeating ) - 1 ;
if ( step = = MEASURE )
{
extra_glyphs_needed + = n_copies * n_repeating ;
DEBUG_MSG ( ARABIC , NULL , " will add extra %d copies of repeating tiles " , n_copies ) ;
}
else
{
hb_position_t x_offset = - overlap ;
for ( unsigned int k = end ; k > start ; k - - )
{
hb_glyph_extents_t extents ;
if ( ! font - > get_glyph_extents ( info [ k - 1 ] . codepoint , & extents ) )
extents . width = 0 ;
extents . width - = overlap ;
unsigned int repeat = 1 ;
if ( info [ k - 1 ] . arabic_shaping_action ( ) = = STCH_REPEATING )
repeat + = n_copies ;
DEBUG_MSG ( ARABIC , NULL , " appending %d copies of glyph %d; j=%d " ,
repeat , info [ k - 1 ] . codepoint , j ) ;
for ( unsigned int n = 0 ; n < repeat ; n + + )
{
x_offset - = extents . width ;
pos [ k - 1 ] . x_offset = x_offset ;
/* Append copy. */
- - j ;
info [ j ] = info [ k - 1 ] ;
pos [ j ] = pos [ k - 1 ] ;
}
}
}
}
if ( step = = MEASURE )
{
if ( unlikely ( ! buffer - > ensure ( count + extra_glyphs_needed ) ) )
break ;
}
else
{
assert ( j = = 0 ) ;
buffer - > len = new_len ;
}
}
}
static void
postprocess_glyphs_arabic ( const hb_ot_shape_plan_t * plan ,
hb_buffer_t * buffer ,
hb_font_t * font )
{
apply_stch ( plan , buffer , font ) ;
HB_BUFFER_DEALLOCATE_VAR ( buffer , arabic_shaping_action ) ;
}
const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
{
@ -380,7 +587,7 @@ const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
data_create_arabic ,
data_destroy_arabic ,
NULL , /* preprocess_text */
NULL , /* postprocess_glyphs */
postprocess_glyphs_arabic ,
HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT ,
NULL , /* decompose */
NULL , /* compose */
Behdad Esfahbod
9 years ago