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+/*
+ * 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. */
+ HBUINT16 trackNameID; /* The 'name' table index for this track */
+ OffsetTo<UnsizedArrayOf<FWORD> >
+ 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<Fixed> 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<UnsizedArrayOf<Fixed> > /* Offset to array[nSizes] of size values. */
+ sizeTable;
+ UnsizedArrayOf<TrackTableEntry>
+ 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<TrackData> horizData; /* TrackData for horizontal text */
+ OffsetTo<TrackData> 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 */