third_party/harfbuzz-ng/src/hb-ot-layout-private.hh

   1 /*
   2  * Copyright © 2007,2008,2009  Red Hat, Inc.
   3  * Copyright © 2012  Google, Inc.
   4  *
   5  *  This is part of HarfBuzz, a text shaping library.
   6  *
   7  * Permission is hereby granted, without written agreement and without
   8  * license or royalty fees, to use, copy, modify, and distribute this
   9  * software and its documentation for any purpose, provided that the
  10  * above copyright notice and the following two paragraphs appear in
  11  * all copies of this software.
  12  *
  13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  17  * DAMAGE.
  18  *
  19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  24  *
  25  * Red Hat Author(s): Behdad Esfahbod
  26  * Google Author(s): Behdad Esfahbod
  27  */
  28
  29 #ifndef HB_OT_LAYOUT_PRIVATE_HH
  30 #define HB_OT_LAYOUT_PRIVATE_HH
  31
  32 #include "hb-private.hh"
  33
  34 #include "hb-ot-layout.h"
  35
  36 #include "hb-font-private.hh"
  37 #include "hb-buffer-private.hh"
  38 #include "hb-set-private.hh"
  39
  40
  41 /* buffer var allocations, used during the GSUB/GPOS processing */
  42 #define glyph_props()           var1.u16[0] /* GDEF glyph properties */
  43 #define syllable()              var1.u8[2] /* GSUB/GPOS shaping boundaries */
  44 #define lig_props()             var1.u8[3] /* GSUB/GPOS ligature tracking */
  45
  46 #define hb_ot_layout_from_face(face) ((hb_ot_layout_t *) face->shaper_data.ot)
  47
  48 /*
  49  * GDEF
  50  */
  51
  52 typedef enum {
  53   HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED = 0x0001,
  54   HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH   = 0x0002,
  55   HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE     = 0x0004,
  56   HB_OT_LAYOUT_GLYPH_CLASS_MARK         = 0x0008,
  57   HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT    = 0x0010
  58 } hb_ot_layout_glyph_class_t;
  59
  60
  61
  62 /*
  63  * GSUB/GPOS
  64  */
  65
  66 /* lig_id / lig_comp
  67  *
  68  * When a ligature is formed:
  69  *
  70  *   - The ligature glyph and any marks in between all the same newly allocated
  71  *     lig_id,
  72  *   - The ligature glyph will get lig_num_comps set to the number of components
  73  *   - The marks get lig_comp > 0, reflecting which component of the ligature
  74  *     they were applied to.
  75  *   - This is used in GPOS to attach marks to the right component of a ligature
  76  *     in MarkLigPos.
  77  *
  78  * When a multiple-substitution is done:
  79  *
  80  *   - All resulting glyphs will have lig_id = 0,
  81  *   - The resulting glyphs will have lig_comp = 0, 1, 2, ... respectively.
  82  *   - This is used in GPOS to attach marks to the first component of a
  83  *     multiple substitution in MarkBasePos.
  84  *
  85  * The numbers are also used in GPOS to do mark-to-mark positioning only
  86  * to marks that belong to the same component of a ligature in MarkMarPos.
  87  */
  88 #define IS_LIG_BASE 0x10
  89 static inline void
  90 set_lig_props_for_ligature (hb_glyph_info_t &info, unsigned int lig_id, unsigned int lig_num_comps)
  91 {
  92   info.lig_props() = (lig_id << 5) | IS_LIG_BASE | (lig_num_comps & 0x0F);
  93 }
  94 static inline void
  95 set_lig_props_for_mark (hb_glyph_info_t &info, unsigned int lig_id, unsigned int lig_comp)
  96 {
  97   info.lig_props() = (lig_id << 5) | (lig_comp & 0x0F);
  98 }
  99 static inline void
 100 set_lig_props_for_component (hb_glyph_info_t &info, unsigned int comp)
 101 {
 102   set_lig_props_for_mark (info, 0, comp);
 103 }
 104
 105 static inline unsigned int
 106 get_lig_id (const hb_glyph_info_t &info)
 107 {
 108   return info.lig_props() >> 5;
 109 }
 110 static inline bool
 111 is_a_ligature (const hb_glyph_info_t &info)
 112 {
 113   return !!(info.lig_props() & IS_LIG_BASE);
 114 }
 115 static inline unsigned int
 116 get_lig_comp (const hb_glyph_info_t &info)
 117 {
 118   if (is_a_ligature (info))
 119     return 0;
 120   else
 121     return info.lig_props() & 0x0F;
 122 }
 123 static inline unsigned int
 124 get_lig_num_comps (const hb_glyph_info_t &info)
 125 {
 126   if ((info.glyph_props() & HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE) && is_a_ligature (info))
 127     return info.lig_props() & 0x0F;
 128   else
 129     return 1;
 130 }
 131
 132 static inline uint8_t allocate_lig_id (hb_buffer_t *buffer) {
 133   uint8_t lig_id = buffer->next_serial () & 0x07;
 134   if (unlikely (!lig_id))
 135     lig_id = allocate_lig_id (buffer); /* in case of overflow */
 136   return lig_id;
 137 }
 138
 139
 140 HB_INTERNAL hb_bool_t
 141 hb_ot_layout_would_substitute_lookup_fast (hb_face_t            *face,
 142                                            unsigned int          lookup_index,
 143                                            const hb_codepoint_t *glyphs,
 144                                            unsigned int          glyphs_length,
 145                                            hb_bool_t             zero_context);
 146
 147
 148 /* Should be called before all the substitute_lookup's are done. */
 149 HB_INTERNAL void
 150 hb_ot_layout_substitute_start (hb_font_t    *font,
 151                                hb_buffer_t  *buffer);
 152
 153 HB_INTERNAL hb_bool_t
 154 hb_ot_layout_substitute_lookup (hb_font_t    *font,
 155                                 hb_buffer_t  *buffer,
 156                                 unsigned int  lookup_index,
 157                                 hb_mask_t     mask);
 158
 159 /* Should be called after all the substitute_lookup's are done */
 160 HB_INTERNAL void
 161 hb_ot_layout_substitute_finish (hb_font_t    *font,
 162                                 hb_buffer_t  *buffer);
 163
 164
 165 /* Should be called before all the position_lookup's are done.  Resets positions to zero. */
 166 HB_INTERNAL void
 167 hb_ot_layout_position_start (hb_font_t    *font,
 168                              hb_buffer_t  *buffer);
 169
 170 HB_INTERNAL hb_bool_t
 171 hb_ot_layout_position_lookup (hb_font_t    *font,
 172                               hb_buffer_t  *buffer,
 173                               unsigned int  lookup_index,
 174                               hb_mask_t     mask);
 175
 176 /* Should be called after all the position_lookup's are done */
 177 HB_INTERNAL void
 178 hb_ot_layout_position_finish (hb_font_t    *font,
 179                               hb_buffer_t  *buffer,
 180                               hb_bool_t     zero_width_attached_marks);
 181
 182
 183
 184 /*
 185  * hb_ot_layout_t
 186  */
 187
 188 namespace OT {
 189   struct GDEF;
 190   struct GSUB;
 191   struct GPOS;
 192 }
 193
 194 struct hb_ot_layout_t
 195 {
 196   hb_blob_t *gdef_blob;
 197   hb_blob_t *gsub_blob;
 198   hb_blob_t *gpos_blob;
 199
 200   const struct OT::GDEF *gdef;
 201   const struct OT::GSUB *gsub;
 202   const struct OT::GPOS *gpos;
 203
 204   unsigned int gsub_lookup_count;
 205   unsigned int gpos_lookup_count;
 206
 207   hb_set_digest_t *gsub_digests;
 208   hb_set_digest_t *gpos_digests;
 209 };
 210
 211
 212 HB_INTERNAL hb_ot_layout_t *
 213 _hb_ot_layout_create (hb_face_t *face);
 214
 215 HB_INTERNAL void
 216 _hb_ot_layout_destroy (hb_ot_layout_t *layout);
 217
 218
 219
 220 #endif /* HB_OT_LAYOUT_PRIVATE_HH */