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[hangul] Reorder Hangul tone mark to beginning of syllable, unless font implements it using a zero-width glyph.

This commit is contained in:
Jonathan Kew 2014-01-20 10:35:51 +00:00
parent 103436838d
commit 7244b3fc3b
1 changed files with 58 additions and 1 deletions
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59
src/hb-ot-shape-complex-hangul.cc
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@ -105,6 +105,8 @@ data_destroy_hangul (void *data)
#define isV(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1160, 0x11A7, 0xD7B0, 0xD7C6))
#define isT(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x11A8, 0x11FF, 0xD7CB, 0xD7FB))
#define isHangulTone(u) (hb_in_range<hb_codepoint_t> ((u), 0x302e, 0x302f))
/* buffer var allocations */
#define hangul_shaping_feature() complex_var_u8_0() /* hangul jamo shaping feature */
@ -147,6 +149,9 @@ preprocess_text_hangul (const hb_ot_shape_plan_t *plan,
*
* - If the whole syllable can be precomposed, do that,
* - Otherwise, fully decompose and apply ljmo/vjmo/tjmo features.
* - If a valid syllable is followed by a Hangul tone mark, reorder the tone
* mark to precede the whole syllable - unless it is a zero-width glyph, in
* which case we leave it untouched, assuming it's designed to overstrike.
*
* That is, of the different possible syllables:
*
@ -178,6 +183,56 @@ preprocess_text_hangul (const hb_ot_shape_plan_t *plan,
{
hb_codepoint_t u = buffer->cur().codepoint;
if (isHangulTone (u))
{
/*
* We could cache the width of the tone marks and the existence of dotted-circle,
* but the use of the Hangul tone mark characters seems to be rare enough that
* I didn't bother for now.
*/
if (start < end && end == buffer->out_len)
{
/* Tone mark follows a valid syllable; move it in front, unless it's zero width. */
buffer->next_glyph ();
if (!is_zero_width_char (font, u))
{
hb_glyph_info_t *info = buffer->out_info;
hb_glyph_info_t tone = info[end];
memmove (&info[start + 1], &info[start], (end - start) * sizeof (hb_glyph_info_t));
info[start] = tone;
}
/* Merge clusters across the (possibly reordered) syllable+tone.
* We want to merge even in the zero-width tone mark case here,
* so that clustering behavior isn't dependent on how the tone mark
* is handled by the font.
*/
buffer->merge_out_clusters (start, end + 1);
}
else
{
/* No valid syllable as base for tone mark; try to insert dotted circle. */
if (font->has_glyph (0x25cc))
{
hb_codepoint_t chars[2];
if (is_zero_width_char (font, u)) {
chars[0] = u;
chars[1] = 0x25cc;
} else {
chars[0] = 0x25cc;
chars[1] = u;
}
buffer->replace_glyphs (1, 2, chars);
}
else
{
/* No dotted circle available in the font; just leave tone mark untouched. */
buffer->next_glyph ();
}
}
start = end = buffer->out_len;
continue;
}
start = buffer->out_len; /* Remember current position as a potential syllable start;
* will only be used if we set end to a later position.
*/
@ -318,7 +373,9 @@ preprocess_text_hangul (const hb_ot_shape_plan_t *plan,
}
}
/* Didn't find a recognizable syllable. */
/* Didn't find a recognizable syllable, so we leave end <= start;
* this will prevent tone-mark reordering happening.
*/
buffer->next_glyph ();
}
buffer->swap_buffers ();