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 Fixed 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 OffsetTo<UnsizedArrayOf<FWORD>, HBUINT16, false> 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 Fixed> 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 /* CoreText points are CSS pixels (96 per inch), 97 * NOT typographic points (72 per inch). 98 * 99 * https://developer.apple.com/library/content/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/Explained/Explained.html 100 */ 101 float csspx = ptem * 96.f / 72.f; 102 103 /* 104 * Choose track. 105 */ 106 const TrackTableEntry *trackTableEntry = nullptr; 107 unsigned int count = nTracks; 108 for (unsigned int i = 0; i < count; i++) 109 { 110 /* Note: Seems like the track entries are sorted by values. But the 111 * spec doesn't explicitly say that. It just mentions it in the example. */ 112 113 /* For now we only seek for track entries with zero tracking value */ 114 115 if (trackTable[i].get_track_value () == 0.f) 116 { 117 trackTableEntry = &trackTable[i]; 118 break; 119 } 120 } 121 if (!trackTableEntry) return 0.; 122 123 /* 124 * Choose size. 125 */ 126 unsigned int sizes = nSizes; 127 if (!sizes) return 0.; 128 if (sizes == 1) return trackTableEntry->get_value (base, 0, sizes); 129 130 hb_array_t<const Fixed> size_table ((base+sizeTable).arrayZ, sizes); 131 unsigned int size_index; 132 for (size_index = 0; size_index < sizes - 1; size_index++) 133 if (size_table[size_index].to_float () >= csspx) 134 break; 135 136 return round (interpolate_at (size_index ? size_index - 1 : 0, csspx, 137 *trackTableEntry, base)); 138 } 139 sanitizeAAT::TrackData140 bool sanitize (hb_sanitize_context_t *c, const void *base) const 141 { 142 TRACE_SANITIZE (this); 143 return_trace (likely (c->check_struct (this) && 144 sizeTable.sanitize (c, base, nSizes) && 145 trackTable.sanitize (c, nTracks, base, nSizes))); 146 } 147 148 protected: 149 HBUINT16 nTracks; /* Number of separate tracks included in this table. */ 150 HBUINT16 nSizes; /* Number of point sizes included in this table. */ 151 LOffsetTo<UnsizedArrayOf<Fixed>, false> 152 sizeTable; /* Offset from start of the tracking table to 153 * Array[nSizes] of size values.. */ 154 UnsizedArrayOf<TrackTableEntry> 155 trackTable; /* Array[nTracks] of TrackTableEntry records. */ 156 157 public: 158 DEFINE_SIZE_ARRAY (8, trackTable); 159 }; 160 161 struct trak 162 { 163 enum { tableTag = HB_AAT_TAG_trak }; 164 has_dataAAT::trak165 bool has_data () const { return version.to_int (); } 166 applyAAT::trak167 bool apply (hb_aat_apply_context_t *c) const 168 { 169 TRACE_APPLY (this); 170 171 hb_mask_t trak_mask = c->plan->trak_mask; 172 173 const float ptem = c->font->ptem; 174 if (unlikely (ptem <= 0.f)) 175 return_trace (false); 176 177 hb_buffer_t *buffer = c->buffer; 178 if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction)) 179 { 180 const TrackData &trackData = this+horizData; 181 int tracking = trackData.get_tracking (this, ptem); 182 hb_position_t offset_to_add = c->font->em_scalef_x (tracking / 2); 183 hb_position_t advance_to_add = c->font->em_scalef_x (tracking); 184 foreach_grapheme (buffer, start, end) 185 { 186 if (!(buffer->info[start].mask & trak_mask)) continue; 187 buffer->pos[start].x_advance += advance_to_add; 188 buffer->pos[start].x_offset += offset_to_add; 189 } 190 } 191 else 192 { 193 const TrackData &trackData = this+vertData; 194 int tracking = trackData.get_tracking (this, ptem); 195 hb_position_t offset_to_add = c->font->em_scalef_y (tracking / 2); 196 hb_position_t advance_to_add = c->font->em_scalef_y (tracking); 197 foreach_grapheme (buffer, start, end) 198 { 199 if (!(buffer->info[start].mask & trak_mask)) continue; 200 buffer->pos[start].y_advance += advance_to_add; 201 buffer->pos[start].y_offset += offset_to_add; 202 } 203 } 204 205 return_trace (true); 206 } 207 sanitizeAAT::trak208 bool sanitize (hb_sanitize_context_t *c) const 209 { 210 TRACE_SANITIZE (this); 211 212 return_trace (likely (c->check_struct (this) && 213 version.major == 1 && 214 horizData.sanitize (c, this, this) && 215 vertData.sanitize (c, this, this))); 216 } 217 218 protected: 219 FixedVersion<>version; /* Version of the tracking table 220 * (0x00010000u for version 1.0). */ 221 HBUINT16 format; /* Format of the tracking table (set to 0). */ 222 OffsetTo<TrackData> 223 horizData; /* Offset from start of tracking table to TrackData 224 * for horizontal text (or 0 if none). */ 225 OffsetTo<TrackData> 226 vertData; /* Offset from start of tracking table to TrackData 227 * for vertical text (or 0 if none). */ 228 HBUINT16 reserved; /* Reserved. Set to 0. */ 229 230 public: 231 DEFINE_SIZE_STATIC (12); 232 }; 233 234 } /* namespace AAT */ 235 236 237 #endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */ 238