/* * Copyright © 2018 Ebrahim Byagowi * Copyright © 2018 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. * * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. * * Google Author(s): Behdad Esfahbod */ #ifndef HB_AAT_LAYOUT_TRAK_TABLE_HH #define HB_AAT_LAYOUT_TRAK_TABLE_HH #include "hb-aat-layout-common-private.hh" #include "hb-open-type-private.hh" #define HB_AAT_TAG_trak HB_TAG('t','r','a','k') namespace AAT { struct TrackTableEntry { inline bool sanitize (hb_sanitize_context_t *c, const void *base, unsigned int size) const { TRACE_SANITIZE (this); return_trace (c->check_struct (this) && (values.sanitize (c, base, size))); } inline float get_track_value () const { return track.to_float (); } inline int get_value (const void *base, unsigned int index) const { return (base+values)[index]; } protected: Fixed track; /* Track value for this record. */ NameID trackNameID; /* The 'name' table index for this track */ OffsetTo > values; /* Offset from start of tracking table to * per-size tracking values for this track. */ public: DEFINE_SIZE_STATIC (8); }; struct TrackData { inline bool sanitize (hb_sanitize_context_t *c, const void *base) const { TRACE_SANITIZE (this); return_trace (c->check_struct (this) && sizeTable.sanitize (c, base, nSizes) && trackTable.sanitize (c, nTracks, base, nSizes)); } inline float get_tracking (const void *base, float ptem) const { /* CoreText points are CSS pixels (96 per inch), * NOT typographic points (72 per inch). * * https://developer.apple.com/library/content/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/Explained/Explained.html */ float csspx = ptem * 96.f / 72.f; Fixed fixed_size; fixed_size.set_float (csspx); /* XXX Clean this up. Make it work with nSizes==1 and 0. */ unsigned int sizes = nSizes; const TrackTableEntry *trackTableEntry = nullptr; for (unsigned int i = 0; i < sizes; ++i) // For now we only seek for track entries with zero tracking value if (trackTable[i].get_track_value () == 0.) trackTableEntry = &trackTable[0]; // We couldn't match any, exit if (!trackTableEntry) return 0.; /* TODO bfind() */ unsigned int size_index; UnsizedArrayOf size_table = base+sizeTable; for (size_index = 0; size_index < sizes; ++size_index) if (size_table[size_index] >= fixed_size) break; // TODO(ebraminio): We don't attempt to extrapolate to larger or // smaller values for now but we should do, per spec if (size_index == sizes) return trackTableEntry->get_value (base, sizes - 1); if (size_index == 0 || size_table[size_index] == fixed_size) return trackTableEntry->get_value (base, size_index); float s0 = size_table[size_index - 1].to_float (); float s1 = size_table[size_index].to_float (); float t = (csspx - s0) / (s1 - s0); return t * trackTableEntry->get_value (base, size_index) + (1.0 - t) * trackTableEntry->get_value (base, size_index - 1); } protected: HBUINT16 nTracks; /* Number of separate tracks included in this table. */ HBUINT16 nSizes; /* Number of point sizes included in this table. */ LOffsetTo > /* Offset to array[nSizes] of size values. */ sizeTable; UnsizedArrayOf trackTable; /* Array[nTracks] of TrackTableEntry records. */ public: DEFINE_SIZE_ARRAY (8, trackTable); }; struct trak { static const hb_tag_t tableTag = HB_AAT_TAG_trak; inline bool sanitize (hb_sanitize_context_t *c) const { TRACE_SANITIZE (this); return_trace (c->check_struct (this) && horizData.sanitize (c, this, this) && vertData.sanitize (c, this, this)); } inline bool apply (hb_aat_apply_context_t *c) const { TRACE_APPLY (this); const float ptem = c->font->ptem; if (ptem <= 0.f) return_trace (false); hb_buffer_t *buffer = c->buffer; if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction)) { const TrackData &trackData = this+horizData; float tracking = trackData.get_tracking (this, ptem); hb_position_t advance_to_add = c->font->em_scalef_x (tracking / 2); foreach_grapheme (buffer, start, end) { /* TODO This is wrong. */ buffer->pos[start].x_advance += advance_to_add; buffer->pos[end].x_advance += advance_to_add; } } else { const TrackData &trackData = this+vertData; float tracking = trackData.get_tracking (this, ptem); hb_position_t advance_to_add = c->font->em_scalef_y (tracking / 2); foreach_grapheme (buffer, start, end) { /* TODO This is wrong. */ buffer->pos[start].y_advance += advance_to_add; buffer->pos[end].y_advance += advance_to_add; } } return_trace (true); } protected: FixedVersion<> version; /* Version of the tracking table--currently * 0x00010000u for version 1.0. */ HBUINT16 format; /* Format of the tracking table */ OffsetTo horizData; /* TrackData for horizontal text */ OffsetTo vertData; /* TrackData for vertical text */ HBUINT16 reserved; /* Reserved. Set to 0. */ public: DEFINE_SIZE_MIN (12); }; } /* namespace AAT */ #endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */