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Diffstat (limited to 'gfx/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh')
| -rw-r--r-- | gfx/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh b/gfx/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh new file mode 100644 index 0000000000..e7a69008b7 --- /dev/null +++ b/gfx/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh @@ -0,0 +1,383 @@ +/* + * Copyright © 2012 Google, Inc. + * + * This is part of HarfBuzz, a text shaping library. + * + * Permission is hereby granted, without written agreement and without + * license or royalty fees, to use, copy, modify, and distribute this + * software and its documentation for any purpose, provided that the + * above copyright notice and the following two paragraphs appear in + * all copies of this software. + * + * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR + * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES + * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN + * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH + * DAMAGE. + * + * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, + * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND + * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS + * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO + * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. + * + * Google Author(s): Behdad Esfahbod + */ + +#ifndef HB_OT_SHAPER_ARABIC_FALLBACK_HH +#define HB_OT_SHAPER_ARABIC_FALLBACK_HH + +#include "hb.hh" + +#include "hb-ot-shape.hh" +#include "hb-ot-layout-gsub-table.hh" + + +/* Features ordered the same as the entries in shaping_table rows, + * followed by rlig. Don't change. + * + * We currently support one subtable per lookup, and one lookup + * per feature. But we allow duplicate features, so we use that! + */ +static const hb_tag_t arabic_fallback_features[] = +{ + HB_TAG('i','n','i','t'), + HB_TAG('m','e','d','i'), + HB_TAG('f','i','n','a'), + HB_TAG('i','s','o','l'), + HB_TAG('r','l','i','g'), + HB_TAG('r','l','i','g'), + HB_TAG('r','l','i','g'), +}; + +static OT::SubstLookup * +arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_font_t *font, + unsigned int feature_index) +{ + OT::HBGlyphID16 glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1]; + OT::HBGlyphID16 substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1]; + unsigned int num_glyphs = 0; + + /* Populate arrays */ + for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++) + { + hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index]; + hb_codepoint_t u_glyph, s_glyph; + + if (!s || + !hb_font_get_glyph (font, u, 0, &u_glyph) || + !hb_font_get_glyph (font, s, 0, &s_glyph) || + u_glyph == s_glyph || + u_glyph > 0xFFFFu || s_glyph > 0xFFFFu) + continue; + + glyphs[num_glyphs] = u_glyph; + substitutes[num_glyphs] = s_glyph; + + num_glyphs++; + } + + if (!num_glyphs) + return nullptr; + + /* Bubble-sort or something equally good! + * May not be good-enough for presidential candidate interviews, but good-enough for us... */ + hb_stable_sort (&glyphs[0], num_glyphs, + (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp, + &substitutes[0]); + + + /* Each glyph takes four bytes max, and there's some overhead. */ + char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128]; + hb_serialize_context_t c (buf, sizeof (buf)); + OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> (); + bool ret = lookup->serialize_single (&c, + OT::LookupFlag::IgnoreMarks, + hb_sorted_array (glyphs, num_glyphs), + hb_array (substitutes, num_glyphs)); + c.end_serialize (); + + return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr; +} + +template <typename T> +static OT::SubstLookup * +arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_font_t *font, + const T &ligature_table, + unsigned lookup_flags) +{ + OT::HBGlyphID16 first_glyphs[ARRAY_LENGTH_CONST (ligature_table)]; + unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)]; + unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)]; + unsigned int num_first_glyphs = 0; + + /* We know that all our ligatures have the same number of components. */ + OT::HBGlyphID16 ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)]; + unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)]; + OT::HBGlyphID16 component_list[ARRAY_LENGTH_CONST (ligature_list) * + ARRAY_LENGTH_CONST (ligature_table[0].ligatures[0].components)]; + unsigned int num_ligatures = 0; + unsigned int num_components = 0; + + /* Populate arrays */ + + /* Sort out the first-glyphs */ + for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++) + { + hb_codepoint_t first_u = ligature_table[first_glyph_idx].first; + hb_codepoint_t first_glyph; + if (!hb_font_get_glyph (font, first_u, 0, &first_glyph)) + continue; + first_glyphs[num_first_glyphs] = first_glyph; + ligature_per_first_glyph_count_list[num_first_glyphs] = 0; + first_glyphs_indirection[num_first_glyphs] = first_glyph_idx; + num_first_glyphs++; + } + hb_stable_sort (&first_glyphs[0], num_first_glyphs, + (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp, + &first_glyphs_indirection[0]); + + /* Now that the first-glyphs are sorted, walk again, populate ligatures. */ + for (unsigned int i = 0; i < num_first_glyphs; i++) + { + unsigned int first_glyph_idx = first_glyphs_indirection[i]; + + for (unsigned int ligature_idx = 0; ligature_idx < ARRAY_LENGTH (ligature_table[0].ligatures); ligature_idx++) + { + hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].ligature; + hb_codepoint_t ligature_glyph; + if (!hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph)) + continue; + + const auto &components = ligature_table[first_glyph_idx].ligatures[ligature_idx].components; + unsigned component_count = ARRAY_LENGTH_CONST (components); + + bool matched = true; + for (unsigned j = 0; j < component_count; j++) + { + hb_codepoint_t component_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[j]; + hb_codepoint_t component_glyph; + if (!component_u || + !hb_font_get_nominal_glyph (font, component_u, &component_glyph)) + { + matched = false; + break; + } + + component_list[num_components++] = component_glyph; + } + if (!matched) + continue; + + component_count_list[num_ligatures] = 1 + component_count; + ligature_list[num_ligatures] = ligature_glyph; + + ligature_per_first_glyph_count_list[i]++; + + num_ligatures++; + } + } + + if (!num_ligatures) + return nullptr; + + + /* 16 bytes per ligature ought to be enough... */ + char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128]; + hb_serialize_context_t c (buf, sizeof (buf)); + OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> (); + bool ret = lookup->serialize_ligature (&c, + lookup_flags, + hb_sorted_array (first_glyphs, num_first_glyphs), + hb_array (ligature_per_first_glyph_count_list, num_first_glyphs), + hb_array (ligature_list, num_ligatures), + hb_array (component_count_list, num_ligatures), + hb_array (component_list, num_components)); + c.end_serialize (); + + return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr; +} + +static OT::SubstLookup * +arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + unsigned int feature_index) +{ + if (feature_index < 4) + return arabic_fallback_synthesize_lookup_single (plan, font, feature_index); + else + { + switch (feature_index) { + case 4: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_3_table, OT::LookupFlag::IgnoreMarks); + case 5: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_table, OT::LookupFlag::IgnoreMarks); + case 6: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_mark_table, 0); + } + } + assert (false); + return nullptr; +} + +#define ARABIC_FALLBACK_MAX_LOOKUPS ARRAY_LENGTH_CONST (arabic_fallback_features) + +struct arabic_fallback_plan_t +{ + unsigned int num_lookups; + bool free_lookups; + + hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS]; + OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS]; + OT::hb_ot_layout_lookup_accelerator_t *accel_array[ARABIC_FALLBACK_MAX_LOOKUPS]; +}; + +#if defined(_WIN32) && !defined(HB_NO_WIN1256) +#define HB_WITH_WIN1256 +#endif + +#ifdef HB_WITH_WIN1256 +#include "hb-ot-shaper-arabic-win1256.hh" +#endif + +struct ManifestLookup +{ + public: + OT::Tag tag; + OT::Offset16To<OT::SubstLookup> lookupOffset; + public: + DEFINE_SIZE_STATIC (6); +}; +typedef OT::Array16Of<ManifestLookup> Manifest; + +static bool +arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED, + const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_font_t *font HB_UNUSED) +{ +#ifdef HB_WITH_WIN1256 + /* Does this font look like it's Windows-1256-encoded? */ + hb_codepoint_t g; + if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ && + hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ && + hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ && + hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ && + hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */)) + return false; + + const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest); + static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) <= + ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), ""); + + unsigned j = 0; + unsigned int count = manifest.len; + for (unsigned int i = 0; i < count; i++) + { + fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag); + if (fallback_plan->mask_array[j]) + { + fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset)); + if (fallback_plan->lookup_array[j]) + { + fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]); + j++; + } + } + } + + fallback_plan->num_lookups = j; + fallback_plan->free_lookups = false; + + return j > 0; +#else + return false; +#endif +} + +static bool +arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan, + const hb_ot_shape_plan_t *plan, + hb_font_t *font) +{ + static_assert ((ARRAY_LENGTH_CONST (arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), ""); + unsigned int j = 0; + for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++) + { + fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]); + if (fallback_plan->mask_array[j]) + { + fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i); + if (fallback_plan->lookup_array[j]) + { + fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]); + j++; + } + } + } + + fallback_plan->num_lookups = j; + fallback_plan->free_lookups = true; + + return j > 0; +} + +static arabic_fallback_plan_t * +arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan, + hb_font_t *font) +{ + arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_calloc (1, sizeof (arabic_fallback_plan_t)); + if (unlikely (!fallback_plan)) + return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t)); + + fallback_plan->num_lookups = 0; + fallback_plan->free_lookups = false; + + /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms, + * in case the font has cmap entries for the presentation-forms characters. */ + if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font)) + return fallback_plan; + + /* See if this looks like a Windows-1256-encoded font. If it does, use a + * hand-coded GSUB table. */ + if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font)) + return fallback_plan; + + assert (fallback_plan->num_lookups == 0); + hb_free (fallback_plan); + return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t)); +} + +static void +arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan) +{ + if (!fallback_plan || fallback_plan->num_lookups == 0) + return; + + for (unsigned int i = 0; i < fallback_plan->num_lookups; i++) + if (fallback_plan->lookup_array[i]) + { + hb_free (fallback_plan->accel_array[i]); + if (fallback_plan->free_lookups) + hb_free (fallback_plan->lookup_array[i]); + } + + hb_free (fallback_plan); +} + +static void +arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan, + hb_font_t *font, + hb_buffer_t *buffer) +{ + OT::hb_ot_apply_context_t c (0, font, buffer); + for (unsigned int i = 0; i < fallback_plan->num_lookups; i++) + if (fallback_plan->lookup_array[i]) { + c.set_lookup_mask (fallback_plan->mask_array[i]); + if (fallback_plan->accel_array[i]) + hb_ot_layout_substitute_lookup (&c, + *fallback_plan->lookup_array[i], + *fallback_plan->accel_array[i]); + } +} + + +#endif /* HB_OT_SHAPER_ARABIC_FALLBACK_HH */ |