michael@0: /*
michael@0:  * Copyright © 2012  Google, Inc.
michael@0:  *
michael@0:  *  This is part of HarfBuzz, a text shaping library.
michael@0:  *
michael@0:  * Permission is hereby granted, without written agreement and without
michael@0:  * license or royalty fees, to use, copy, modify, and distribute this
michael@0:  * software and its documentation for any purpose, provided that the
michael@0:  * above copyright notice and the following two paragraphs appear in
michael@0:  * all copies of this software.
michael@0:  *
michael@0:  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
michael@0:  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
michael@0:  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
michael@0:  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
michael@0:  * DAMAGE.
michael@0:  *
michael@0:  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
michael@0:  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
michael@0:  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
michael@0:  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
michael@0:  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
michael@0:  *
michael@0:  * Google Author(s): Behdad Esfahbod
michael@0:  */
michael@0: 
michael@0: #ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
michael@0: #define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
michael@0: 
michael@0: #include "hb-private.hh"
michael@0: 
michael@0: #include "hb-ot-shape-private.hh"
michael@0: #include "hb-ot-layout-gsub-table.hh"
michael@0: 
michael@0: 
michael@0: static const hb_tag_t arabic_fallback_features[] =
michael@0: {
michael@0:   HB_TAG('i','n','i','t'),
michael@0:   HB_TAG('m','e','d','i'),
michael@0:   HB_TAG('f','i','n','a'),
michael@0:   HB_TAG('i','s','o','l'),
michael@0:   HB_TAG('r','l','i','g'),
michael@0: };
michael@0: 
michael@0: /* Same order as the fallback feature array */
michael@0: enum {
michael@0:   FALLBACK_INIT,
michael@0:   FALLBACK_MEDI,
michael@0:   FALLBACK_FINA,
michael@0:   FALLBACK_ISOL,
michael@0:   FALLBACK_RLIG,
michael@0:   ARABIC_NUM_FALLBACK_FEATURES
michael@0: };
michael@0: 
michael@0: static OT::SubstLookup *
michael@0: arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
michael@0: 					  hb_font_t *font,
michael@0: 					  unsigned int feature_index)
michael@0: {
michael@0:   OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
michael@0:   OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
michael@0:   unsigned int num_glyphs = 0;
michael@0: 
michael@0:   /* Populate arrays */
michael@0:   for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
michael@0:   {
michael@0:     hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
michael@0:     hb_codepoint_t u_glyph, s_glyph;
michael@0: 
michael@0:     if (!s ||
michael@0: 	!hb_font_get_glyph (font, u, 0, &u_glyph) ||
michael@0: 	!hb_font_get_glyph (font, s, 0, &s_glyph) ||
michael@0: 	u_glyph == s_glyph ||
michael@0: 	u_glyph > 0xFFFF || s_glyph > 0xFFFF)
michael@0:       continue;
michael@0: 
michael@0:     glyphs[num_glyphs].set (u_glyph);
michael@0:     substitutes[num_glyphs].set (s_glyph);
michael@0: 
michael@0:     num_glyphs++;
michael@0:   }
michael@0: 
michael@0:   /* Bubble-sort!
michael@0:    * May not be good-enough for presidential candidate interviews, but good-enough for us... */
michael@0:   hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);
michael@0: 
michael@0:   OT::Supplier<OT::GlyphID> glyphs_supplier      (glyphs, num_glyphs);
michael@0:   OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);
michael@0: 
michael@0:   /* Each glyph takes four bytes max, and there's some overhead. */
michael@0:   char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
michael@0:   OT::hb_serialize_context_t c (buf, sizeof (buf));
michael@0:   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
michael@0:   bool ret = lookup->serialize_single (&c,
michael@0: 				       OT::LookupFlag::IgnoreMarks,
michael@0: 				       glyphs_supplier,
michael@0: 				       substitutes_supplier,
michael@0: 				       num_glyphs);
michael@0:   c.end_serialize ();
michael@0:   /* TODO sanitize the results? */
michael@0: 
michael@0:   return ret ? c.copy<OT::SubstLookup> () : NULL;
michael@0: }
michael@0: 
michael@0: static OT::SubstLookup *
michael@0: arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
michael@0: 					    hb_font_t *font)
michael@0: {
michael@0:   OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
michael@0:   unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
michael@0:   unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
michael@0:   unsigned int num_first_glyphs = 0;
michael@0: 
michael@0:   /* We know that all our ligatures are 2-component */
michael@0:   OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
michael@0:   unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
michael@0:   OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
michael@0:   unsigned int num_ligatures = 0;
michael@0: 
michael@0:   /* Populate arrays */
michael@0: 
michael@0:   /* Sort out the first-glyphs */
michael@0:   for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
michael@0:   {
michael@0:     hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
michael@0:     hb_codepoint_t first_glyph;
michael@0:     if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
michael@0:       continue;
michael@0:     first_glyphs[num_first_glyphs].set (first_glyph);
michael@0:     ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
michael@0:     first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
michael@0:     num_first_glyphs++;
michael@0:   }
michael@0:   hb_bubble_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);
michael@0: 
michael@0:   /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
michael@0:   for (unsigned int i = 0; i < num_first_glyphs; i++)
michael@0:   {
michael@0:     unsigned int first_glyph_idx = first_glyphs_indirection[i];
michael@0: 
michael@0:     for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
michael@0:     {
michael@0:       hb_codepoint_t second_u   = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
michael@0:       hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
michael@0:       hb_codepoint_t second_glyph, ligature_glyph;
michael@0:       if (!second_u ||
michael@0: 	  !hb_font_get_glyph (font, second_u,   0, &second_glyph) ||
michael@0: 	  !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
michael@0: 	continue;
michael@0: 
michael@0:       ligature_per_first_glyph_count_list[i]++;
michael@0: 
michael@0:       ligature_list[num_ligatures].set (ligature_glyph);
michael@0:       component_count_list[num_ligatures] = 2;
michael@0:       component_list[num_ligatures].set (second_glyph);
michael@0:       num_ligatures++;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   OT::Supplier<OT::GlyphID>   first_glyphs_supplier                      (first_glyphs, num_first_glyphs);
michael@0:   OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier    (ligature_per_first_glyph_count_list, num_first_glyphs);
michael@0:   OT::Supplier<OT::GlyphID>   ligatures_supplier                         (ligature_list, num_ligatures);
michael@0:   OT::Supplier<unsigned int > component_count_supplier                   (component_count_list, num_ligatures);
michael@0:   OT::Supplier<OT::GlyphID>   component_supplier                         (component_list, num_ligatures);
michael@0: 
michael@0:   /* 16 bytes per ligature ought to be enough... */
michael@0:   char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
michael@0:   OT::hb_serialize_context_t c (buf, sizeof (buf));
michael@0:   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
michael@0:   bool ret = lookup->serialize_ligature (&c,
michael@0: 					 OT::LookupFlag::IgnoreMarks,
michael@0: 					 first_glyphs_supplier,
michael@0: 					 ligature_per_first_glyph_count_supplier,
michael@0: 					 num_first_glyphs,
michael@0: 					 ligatures_supplier,
michael@0: 					 component_count_supplier,
michael@0: 					 component_supplier);
michael@0: 
michael@0:   c.end_serialize ();
michael@0:   /* TODO sanitize the results? */
michael@0: 
michael@0:   return ret ? c.copy<OT::SubstLookup> () : NULL;
michael@0: }
michael@0: 
michael@0: static OT::SubstLookup *
michael@0: arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
michael@0: 				   hb_font_t *font,
michael@0: 				   unsigned int feature_index)
michael@0: {
michael@0:   if (feature_index < 4)
michael@0:     return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
michael@0:   else
michael@0:     return arabic_fallback_synthesize_lookup_ligature (plan, font);
michael@0: }
michael@0: 
michael@0: struct arabic_fallback_plan_t
michael@0: {
michael@0:   ASSERT_POD ();
michael@0: 
michael@0:   hb_mask_t mask_array[ARABIC_NUM_FALLBACK_FEATURES];
michael@0:   OT::SubstLookup *lookup_array[ARABIC_NUM_FALLBACK_FEATURES];
michael@0:   hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_NUM_FALLBACK_FEATURES];
michael@0: };
michael@0: 
michael@0: static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
michael@0: 
michael@0: static arabic_fallback_plan_t *
michael@0: arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
michael@0: 			     hb_font_t *font)
michael@0: {
michael@0:   arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
michael@0:   if (unlikely (!fallback_plan))
michael@0:     return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
michael@0: 
michael@0:   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
michael@0:   {
michael@0:     fallback_plan->mask_array[i] = plan->map.get_1_mask (arabic_fallback_features[i]);
michael@0:     if (fallback_plan->mask_array[i]) {
michael@0:       fallback_plan->lookup_array[i] = arabic_fallback_synthesize_lookup (plan, font, i);
michael@0:       if (fallback_plan->lookup_array[i])
michael@0: 	fallback_plan->accel_array[i].init (*fallback_plan->lookup_array[i]);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return fallback_plan;
michael@0: }
michael@0: 
michael@0: static void
michael@0: arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
michael@0: {
michael@0:   if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
michael@0:     return;
michael@0: 
michael@0:   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
michael@0:     if (fallback_plan->lookup_array[i])
michael@0:     {
michael@0:       fallback_plan->accel_array[i].fini (fallback_plan->lookup_array[i]);
michael@0:       free (fallback_plan->lookup_array[i]);
michael@0:     }
michael@0: 
michael@0:   free (fallback_plan);
michael@0: }
michael@0: 
michael@0: static void
michael@0: arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
michael@0: 			    hb_font_t *font,
michael@0: 			    hb_buffer_t *buffer)
michael@0: {
michael@0:   OT::hb_apply_context_t c (0, font, buffer);
michael@0:   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
michael@0:     if (fallback_plan->lookup_array[i]) {
michael@0:       c.set_lookup_mask (fallback_plan->mask_array[i]);
michael@0:       hb_ot_layout_substitute_lookup (&c,
michael@0: 				      *fallback_plan->lookup_array[i],
michael@0: 				      fallback_plan->accel_array[i]);
michael@0:     }
michael@0: }
michael@0: 
michael@0: 
michael@0: #endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */