1 /* 2 * Copyright © 2018 Ebrahim Byagowi 3 * Copyright © 2018 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 * Google Author(s): Behdad Esfahbod 26 */ 27 28 #ifndef HB_AAT_LAYOUT_TRAK_TABLE_HH 29 #define HB_AAT_LAYOUT_TRAK_TABLE_HH 30 31 #include "hb-aat-layout-common.hh" 32 #include "hb-ot-layout.hh" 33 #include "hb-open-type.hh" 34 35 /* 36 * trak -- Tracking 37 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6trak.html 38 */ 39 #define HB_AAT_TAG_trak HB_TAG('t','r','a','k') 40 41 42 namespace AAT { 43 44 45 struct TrackTableEntry 46 { 47 friend struct TrackData; 48 get_track_valueAAT::TrackTableEntry49 float get_track_value () const { return track.to_float (); } 50 get_valueAAT::TrackTableEntry51 int get_value (const void *base, unsigned int index, 52 unsigned int table_size) const 53 { return (base+valuesZ).as_array (table_size)[index]; } 54 55 public: sanitizeAAT::TrackTableEntry56 bool sanitize (hb_sanitize_context_t *c, const void *base, 57 unsigned int table_size) const 58 { 59 TRACE_SANITIZE (this); 60 return_trace (likely (c->check_struct (this) && 61 (valuesZ.sanitize (c, base, table_size)))); 62 } 63 64 protected: 65 HBFixed track; /* Track value for this record. */ 66 NameID trackNameID; /* The 'name' table index for this track. 67 * (a short word or phrase like "loose" 68 * or "very tight") */ 69 NNOffset16To<UnsizedArrayOf<FWORD>> 70 valuesZ; /* Offset from start of tracking table to 71 * per-size tracking values for this track. */ 72 73 public: 74 DEFINE_SIZE_STATIC (8); 75 }; 76 77 struct TrackData 78 { interpolate_atAAT::TrackData79 float interpolate_at (unsigned int idx, 80 float target_size, 81 const TrackTableEntry &trackTableEntry, 82 const void *base) const 83 { 84 unsigned int sizes = nSizes; 85 hb_array_t<const HBFixed> size_table ((base+sizeTable).arrayZ, sizes); 86 87 float s0 = size_table[idx].to_float (); 88 float s1 = size_table[idx + 1].to_float (); 89 float t = unlikely (s0 == s1) ? 0.f : (target_size - s0) / (s1 - s0); 90 return t * trackTableEntry.get_value (base, idx + 1, sizes) + 91 (1.f - t) * trackTableEntry.get_value (base, idx, sizes); 92 } 93 get_trackingAAT::TrackData94 int get_tracking (const void *base, float ptem) const 95 { 96 /* 97 * Choose track. 98 */ 99 const TrackTableEntry *trackTableEntry = nullptr; 100 unsigned int count = nTracks; 101 for (unsigned int i = 0; i < count; i++) 102 { 103 /* Note: Seems like the track entries are sorted by values. But the 104 * spec doesn't explicitly say that. It just mentions it in the example. */ 105 106 /* For now we only seek for track entries with zero tracking value */ 107 108 if (trackTable[i].get_track_value () == 0.f) 109 { 110 trackTableEntry = &trackTable[i]; 111 break; 112 } 113 } 114 if (!trackTableEntry) return 0.; 115 116 /* 117 * Choose size. 118 */ 119 unsigned int sizes = nSizes; 120 if (!sizes) return 0.; 121 if (sizes == 1) return trackTableEntry->get_value (base, 0, sizes); 122 123 hb_array_t<const HBFixed> size_table ((base+sizeTable).arrayZ, sizes); 124 unsigned int size_index; 125 for (size_index = 0; size_index < sizes - 1; size_index++) 126 if (size_table[size_index].to_float () >= ptem) 127 break; 128 129 return roundf (interpolate_at (size_index ? size_index - 1 : 0, ptem, 130 *trackTableEntry, base)); 131 } 132 sanitizeAAT::TrackData133 bool sanitize (hb_sanitize_context_t *c, const void *base) const 134 { 135 TRACE_SANITIZE (this); 136 return_trace (likely (c->check_struct (this) && 137 sizeTable.sanitize (c, base, nSizes) && 138 trackTable.sanitize (c, nTracks, base, nSizes))); 139 } 140 141 protected: 142 HBUINT16 nTracks; /* Number of separate tracks included in this table. */ 143 HBUINT16 nSizes; /* Number of point sizes included in this table. */ 144 NNOffset32To<UnsizedArrayOf<HBFixed>> 145 sizeTable; /* Offset from start of the tracking table to 146 * Array[nSizes] of size values.. */ 147 UnsizedArrayOf<TrackTableEntry> 148 trackTable; /* Array[nTracks] of TrackTableEntry records. */ 149 150 public: 151 DEFINE_SIZE_ARRAY (8, trackTable); 152 }; 153 154 struct trak 155 { 156 static constexpr hb_tag_t tableTag = HB_AAT_TAG_trak; 157 has_dataAAT::trak158 bool has_data () const { return version.to_int (); } 159 applyAAT::trak160 bool apply (hb_aat_apply_context_t *c) const 161 { 162 TRACE_APPLY (this); 163 164 hb_mask_t trak_mask = c->plan->trak_mask; 165 166 const float ptem = c->font->ptem; 167 if (unlikely (ptem <= 0.f)) 168 return_trace (false); 169 170 hb_buffer_t *buffer = c->buffer; 171 if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction)) 172 { 173 const TrackData &trackData = this+horizData; 174 int tracking = trackData.get_tracking (this, ptem); 175 hb_position_t offset_to_add = c->font->em_scalef_x (tracking / 2); 176 hb_position_t advance_to_add = c->font->em_scalef_x (tracking); 177 foreach_grapheme (buffer, start, end) 178 { 179 if (!(buffer->info[start].mask & trak_mask)) continue; 180 buffer->pos[start].x_advance += advance_to_add; 181 buffer->pos[start].x_offset += offset_to_add; 182 } 183 } 184 else 185 { 186 const TrackData &trackData = this+vertData; 187 int tracking = trackData.get_tracking (this, ptem); 188 hb_position_t offset_to_add = c->font->em_scalef_y (tracking / 2); 189 hb_position_t advance_to_add = c->font->em_scalef_y (tracking); 190 foreach_grapheme (buffer, start, end) 191 { 192 if (!(buffer->info[start].mask & trak_mask)) continue; 193 buffer->pos[start].y_advance += advance_to_add; 194 buffer->pos[start].y_offset += offset_to_add; 195 } 196 } 197 198 return_trace (true); 199 } 200 sanitizeAAT::trak201 bool sanitize (hb_sanitize_context_t *c) const 202 { 203 TRACE_SANITIZE (this); 204 205 return_trace (likely (c->check_struct (this) && 206 version.major == 1 && 207 horizData.sanitize (c, this, this) && 208 vertData.sanitize (c, this, this))); 209 } 210 211 protected: 212 FixedVersion<>version; /* Version of the tracking table 213 * (0x00010000u for version 1.0). */ 214 HBUINT16 format; /* Format of the tracking table (set to 0). */ 215 Offset16To<TrackData> 216 horizData; /* Offset from start of tracking table to TrackData 217 * for horizontal text (or 0 if none). */ 218 Offset16To<TrackData> 219 vertData; /* Offset from start of tracking table to TrackData 220 * for vertical text (or 0 if none). */ 221 HBUINT16 reserved; /* Reserved. Set to 0. */ 222 223 public: 224 DEFINE_SIZE_STATIC (12); 225 }; 226 227 } /* namespace AAT */ 228 229 230 #endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */ 231