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+/*
+ * 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 */