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[Indic] Work around fonts with broken new-spec tables 

See comments, and this thread:

http://lists.freedesktop.org/archives/harfbuzz/2013-March/002990.html

Originally reported here:

https://code.google.com/p/chromium/issues/detail?id=96143

Doesn't change test suite numbers.
This commit is contained in:
Behdad Esfahbod 2013-03-05 20:08:59 -05:00
parent dfb799f575
commit 8144936d07
1 changed files with 29 additions and 13 deletions
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34
src/hb-ot-shape-complex-indic.cc
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@ -457,7 +457,7 @@ struct would_substitute_feature_t
&lookups, &count);
}
inline bool would_substitute (hb_codepoint_t *glyphs,
inline bool would_substitute (const hb_codepoint_t *glyphs,
unsigned int glyphs_count,
bool zero_context,
hb_face_t *face) const
@ -546,13 +546,30 @@ data_destroy_indic (void *data)
static indic_position_t
consonant_position_from_face (const indic_shape_plan_t *indic_plan,
hb_codepoint_t *glyphs, unsigned int glyphs_len,
const hb_codepoint_t glyphs[2],
hb_face_t *face)
{
/* For old-spec, the order of glyphs is Consonant,Virama,
* whereas for new-spec, it's Virama,Consonant. However,
* some broken fonts (like Free Sans) simply copied lookups
* from old-spec to new-spec without modification.
* And oddly enough, Uniscribe seems to respect those lookups.
* Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
* base at 0. The font however, only has lookups matching
* 930,94D in 'blwf', not the expected 94D,930 (with new-spec
* table). As such, we simply match both sequences. Seems
* to work. */
bool zero_context = indic_plan->is_old_spec ? false : true;
if (indic_plan->pref.would_substitute (glyphs, glyphs_len, zero_context, face)) return POS_POST_C;
if (indic_plan->blwf.would_substitute (glyphs, glyphs_len, zero_context, face)) return POS_BELOW_C;
if (indic_plan->pstf.would_substitute (glyphs, glyphs_len, zero_context, face)) return POS_POST_C;
hb_codepoint_t glyphs_r[2] = {glyphs[1], glyphs[0]};
if (indic_plan->pref.would_substitute (glyphs , 2, zero_context, face) ||
indic_plan->pref.would_substitute (glyphs_r, 2, zero_context, face))
return POS_POST_C;
if (indic_plan->blwf.would_substitute (glyphs , 2, zero_context, face) ||
indic_plan->blwf.would_substitute (glyphs_r, 2, zero_context, face))
return POS_BELOW_C;
if (indic_plan->pstf.would_substitute (glyphs , 2, zero_context, face) ||
indic_plan->pstf.would_substitute (glyphs_r, 2, zero_context, face))
return POS_POST_C;
return POS_BASE_C;
}
@ -610,16 +627,15 @@ update_consonant_positions (const hb_ot_shape_plan_t *plan,
{
const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
unsigned int consonant_pos = indic_plan->is_old_spec ? 0 : 1;
hb_codepoint_t glyphs[2];
if (indic_plan->get_virama_glyph (font, &glyphs[1 - consonant_pos]))
if (indic_plan->get_virama_glyph (font, &glyphs[0]))
{
hb_face_t *face = font->face;
unsigned int count = buffer->len;
for (unsigned int i = 0; i < count; i++)
if (buffer->info[i].indic_position() == POS_BASE_C) {
glyphs[consonant_pos] = buffer->info[i].codepoint;
buffer->info[i].indic_position() = consonant_position_from_face (indic_plan, glyphs, 2, face);
glyphs[1] = buffer->info[i].codepoint;
buffer->info[i].indic_position() = consonant_position_from_face (indic_plan, glyphs, face);
}
}
}