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Implement Arabic fallback shaping mandatory ligatures

This commit is contained in:
Behdad Esfahbod 2012-04-10 17:20:05 -04:00
parent b7d04eb606
commit 939c010211
4 changed files with 74 additions and 21 deletions
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32
src/gen-arabic-table.py
View File

@ -133,11 +133,7 @@ def print_shaping_table(f):
print "#define SHAPING_TABLE_LAST 0x%04X" % max_u
print
print
print "static const uint16_t ligature_table[][3] ="
print "{"
ligas = []
ligas = {}
for pair in ligatures.keys ():
for shape in ligatures[pair]:
c = ligatures[pair][shape]
@ -147,11 +143,27 @@ def print_shaping_table(f):
liga = (shapes[pair[0]]['medial'], shapes[pair[1]]['final'])
else:
raise Exception ("Unexpected shape", shape)
ligas.append (liga + (c,))
ligas.sort ()
for liga in ligas:
value = ', '.join ("0x%04X" % c for c in liga)
print " {%s}, /* U+%04X %s */" % (value, liga[2], names[liga[2]])
if liga[0] not in ligas:
ligas[liga[0]] = []
ligas[liga[0]].append ((liga[1], c))
max_i = max (len (ligas[l]) for l in ligas)
print
print "static const struct {"
print " uint16_t first;"
print " struct {"
print " uint16_t second;"
print " uint16_t ligature;"
print " } ligatures[%d];" % max_i
print "} ligature_table[] ="
print "{"
keys = ligas.keys ()
keys.sort ()
for first in keys:
print " { 0x%04X, {" % (first)
for liga in ligas[first]:
print " { 0x%04X, 0x%04X }, /* %s */" % (liga[0], liga[1], names[liga[1]])
print " }},"
print "};"
print

28
src/hb-ot-shape-complex-arabic-table.hh
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@ -914,16 +914,26 @@ static const uint16_t shaping_table[][4] =
#define SHAPING_TABLE_LAST 0x06D3
static const uint16_t ligature_table[][3] =
static const struct {
uint16_t first;
struct {
uint16_t second;
uint16_t ligature;
} ligatures[4];
} ligature_table[] =
{
{0xFEDF, 0xFE82, 0xFEF5}, /* U+FEF5 ARABIC LIGATURE LAM WITH ALEF WITH MADDA ABOVE ISOLATED FORM */
{0xFEDF, 0xFE84, 0xFEF7}, /* U+FEF7 ARABIC LIGATURE LAM WITH ALEF WITH HAMZA ABOVE ISOLATED FORM */
{0xFEDF, 0xFE88, 0xFEF9}, /* U+FEF9 ARABIC LIGATURE LAM WITH ALEF WITH HAMZA BELOW ISOLATED FORM */
{0xFEDF, 0xFE8E, 0xFEFB}, /* U+FEFB ARABIC LIGATURE LAM WITH ALEF ISOLATED FORM */
{0xFEE0, 0xFE82, 0xFEF6}, /* U+FEF6 ARABIC LIGATURE LAM WITH ALEF WITH MADDA ABOVE FINAL FORM */
{0xFEE0, 0xFE84, 0xFEF8}, /* U+FEF8 ARABIC LIGATURE LAM WITH ALEF WITH HAMZA ABOVE FINAL FORM */
{0xFEE0, 0xFE88, 0xFEFA}, /* U+FEFA ARABIC LIGATURE LAM WITH ALEF WITH HAMZA BELOW FINAL FORM */
{0xFEE0, 0xFE8E, 0xFEFC}, /* U+FEFC ARABIC LIGATURE LAM WITH ALEF FINAL FORM */
{ 0xFEDF, {
{ 0xFE88, 0xFEF9 }, /* ARABIC LIGATURE LAM WITH ALEF WITH HAMZA BELOW ISOLATED FORM */
{ 0xFE82, 0xFEF5 }, /* ARABIC LIGATURE LAM WITH ALEF WITH MADDA ABOVE ISOLATED FORM */
{ 0xFE8E, 0xFEFB }, /* ARABIC LIGATURE LAM WITH ALEF ISOLATED FORM */
{ 0xFE84, 0xFEF7 }, /* ARABIC LIGATURE LAM WITH ALEF WITH HAMZA ABOVE ISOLATED FORM */
}},
{ 0xFEE0, {
{ 0xFE88, 0xFEFA }, /* ARABIC LIGATURE LAM WITH ALEF WITH HAMZA BELOW FINAL FORM */
{ 0xFE82, 0xFEF6 }, /* ARABIC LIGATURE LAM WITH ALEF WITH MADDA ABOVE FINAL FORM */
{ 0xFE8E, 0xFEFC }, /* ARABIC LIGATURE LAM WITH ALEF FINAL FORM */
{ 0xFE84, 0xFEF8 }, /* ARABIC LIGATURE LAM WITH ALEF WITH HAMZA ABOVE FINAL FORM */
}},
};

31
src/hb-ot-shape-complex-arabic.cc
View File

@ -87,6 +87,16 @@ static hb_codepoint_t get_arabic_shape (hb_codepoint_t u, unsigned int shape)
return u;
}
static uint16_t get_ligature (hb_codepoint_t first, hb_codepoint_t second)
{
if (unlikely (!second)) return 0;
for (unsigned i = 0; i < ARRAY_LENGTH (ligature_table); i++)
if (ligature_table[i].first == first)
for (unsigned j = 0; j < ARRAY_LENGTH (ligature_table[i].ligatures); j++)
if (ligature_table[i].ligatures[j].second == second)
return ligature_table[i].ligatures[j].ligature;
return 0;
}
static const hb_tag_t arabic_syriac_features[] =
{
@ -198,8 +208,29 @@ static void
arabic_fallback_shape (hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
/* Shape to presentation forms */
for (unsigned int i = 0; i < count; i++)
buffer->info[i].codepoint = get_arabic_shape (buffer->info[i].codepoint, buffer->info[i].arabic_shaping_action());
/* Mandatory ligatures */
buffer->clear_output ();
for (buffer->idx = 0; buffer->idx + 1 < count;) {
uint16_t ligature = get_ligature (buffer->info[buffer->idx].codepoint,
buffer->info[buffer->idx + 1].codepoint);
if (likely (!ligature)) {
buffer->next_glyph ();
continue;
}
buffer->replace_glyphs (2, 1, &ligature);
/* Technically speaking we can skip marks and stuff, like the GSUB path does.
* But who cares, we're in fallback! */
}
for (; buffer->idx < count;)
buffer->next_glyph ();
buffer->swap_buffers ();
}
void

4
src/hb-ot-shape-complex-misc.cc
View File

@ -132,7 +132,7 @@ _hb_ot_shape_complex_setup_masks_thai (hb_ot_map_t *map, hb_buffer_t *buffer)
unsigned int count = buffer->len;
for (buffer->idx = 0; buffer->idx < count;)
{
if (!IS_SARA_AM (buffer->info[buffer->idx].codepoint)) {
if (likely (!IS_SARA_AM (buffer->info[buffer->idx].codepoint))) {
buffer->next_glyph ();
continue;
}
@ -141,7 +141,7 @@ _hb_ot_shape_complex_setup_masks_thai (hb_ot_map_t *map, hb_buffer_t *buffer)
uint16_t decomposed[2] = {NIKHAHIT_FROM_SARA_AM (buffer->info[buffer->idx].codepoint),
SARA_AA_FROM_SARA_AM (buffer->info[buffer->idx].codepoint)};
buffer->replace_glyphs (1, 2, decomposed);
if (buffer->in_error)
if (unlikely (buffer->in_error))
return;
/* Ok, let's see... */