Roll HarfBuzz to 0.9.35

third_party/harfbuzz-ng/src/hb-ot-shape-complex-arabic-fallback.hh

 /*
  * 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.
@@ skipping 15 matching lines @@
 
 #ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
 #define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
 
 #include "hb-private.hh"
 
 #include "hb-ot-shape-private.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. */
 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'),
 };
 
-/* Same order as the fallback feature array */
-enum {
-  FALLBACK_INIT,
-  FALLBACK_MEDI,
-  FALLBACK_FINA,
-  FALLBACK_ISOL,
-  FALLBACK_RLIG,
-  ARABIC_NUM_FALLBACK_FEATURES
-};
-
 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::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
   OT::GlyphID 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].set (u_glyph);
     substitutes[num_glyphs].set (s_glyph);
 
     num_glyphs++;
   }
 
+  if (!num_glyphs)
+    return NULL;
+
   /* Bubble-sort!
    * May not be good-enough for presidential candidate interviews, but good-enough for us... */
   hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);
 
   OT::Supplier<OT::GlyphID> glyphs_supplier      (glyphs, num_glyphs);
   OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);
 
   /* Each glyph takes four bytes max, and there's some overhead. */
   char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
   OT::hb_serialize_context_t c (buf, sizeof (buf));
@@ skipping 57 matching lines @@
 
       ligature_per_first_glyph_count_list[i]++;
 
       ligature_list[num_ligatures].set (ligature_glyph);
       component_count_list[num_ligatures] = 2;
       component_list[num_ligatures].set (second_glyph);
       num_ligatures++;
     }
   }
 
+  if (!num_ligatures)
+    return NULL;
+
   OT::Supplier<OT::GlyphID>   first_glyphs_supplier                      (first_glyphs, num_first_glyphs);
   OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier    (ligature_per_first_glyph_count_list, num_first_glyphs);
   OT::Supplier<OT::GlyphID>   ligatures_supplier                         (ligature_list, num_ligatures);
   OT::Supplier<unsigned int > component_count_supplier                   (component_count_list, num_ligatures);
   OT::Supplier<OT::GlyphID>   component_supplier                         (component_list, num_ligatures);
 
   /* 16 bytes per ligature ought to be enough... */
   char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
   OT::hb_serialize_context_t c (buf, sizeof (buf));
   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
@@ skipping 16 matching lines @@
 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
     return arabic_fallback_synthesize_lookup_ligature (plan, font);
 }
 
+#define ARABIC_FALLBACK_MAX_LOOKUPS 5
+
 struct arabic_fallback_plan_t
 {
   ASSERT_POD ();
 
-  hb_mask_t mask_array[ARABIC_NUM_FALLBACK_FEATURES];
-  OT::SubstLookup *lookup_array[ARABIC_NUM_FALLBACK_FEATURES];
-  hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_NUM_FALLBACK_FEATURES];
+  unsigned int num_lookups;
+  bool free_lookups;
+
+  hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
+  OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
+  hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
 };
 
 static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
 
+#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(HB_WITH_WIN1256)
+#define HB_WITH_WIN1256
+#endif
+
+#ifdef HB_WITH_WIN1256
+#include "hb-ot-shape-complex-arabic-win1256.hh"
+#endif
+
+struct ManifestLookup {
+  OT::Tag tag;
+  OT::OffsetTo<OT::SubstLookup> lookupOffset;
+};
+typedef OT::ArrayOf<ManifestLookup> Manifest;
+
+static bool
+arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan,
+                                   const hb_ot_shape_plan_t *plan,
+                                   hb_font_t *font)
+{
+#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);
+  ASSERT_STATIC (sizeof (arabic_win1256_gsub_lookups.manifestData) / sizeof (ManifestLookup)
+                 <= ARABIC_FALLBACK_MAX_LOOKUPS);
+  /* TODO sanitize the table? */
+
+  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].init (*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)
+{
+  ASSERT_STATIC (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].init (*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 *) calloc (1, sizeof (arabic_fallback_plan_t));
   if (unlikely (!fallback_plan))
     return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
 
-  for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
-  {
-    fallback_plan->mask_array[i] = plan->map.get_1_mask (arabic_fallback_features[i]);
-    if (fallback_plan->mask_array[i]) {
-      fallback_plan->lookup_array[i] = arabic_fallback_synthesize_lookup (plan, font, i);
-      if (fallback_plan->lookup_array[i])
-        fallback_plan->accel_array[i].init (*fallback_plan->lookup_array[i]);
-    }
-  }
+  fallback_plan->num_lookups = 0;
+  fallback_plan->free_lookups = false;
 
-  return fallback_plan;
+  /* 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;
+
+  free (fallback_plan);
+  return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
 }
 
 static void
 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
 {
   if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
     return;
 
-  for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
+  for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
     if (fallback_plan->lookup_array[i])
     {
       fallback_plan->accel_array[i].fini (fallback_plan->lookup_array[i]);
-      free (fallback_plan->lookup_array[i]);
+      if (fallback_plan->free_lookups)
+        free (fallback_plan->lookup_array[i]);
     }
 
   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_apply_context_t c (0, font, buffer);
-  for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
+  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]);
       hb_ot_layout_substitute_lookup (&c,
                                       *fallback_plan->lookup_array[i],
                                       fallback_plan->accel_array[i]);
     }
 }
 
 
 #endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */