/*

 * 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.hh"

#include "hb-ot-layout.hh"

#include "hb-open-type.hh"

/*

 * trak -- Tracking

 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6trak.html

 */

#define HB_AAT_TAG_trak HB_TAG('t','r','a','k')

namespace AAT {

struct TrackTableEntry

{

  friend struct TrackData;

  float get_track_value () const { return track.to_float (); }

  int get_value (const void *base, unsigned int index,

     unsigned int table_size) const

  { return (base+valuesZ).as_array (table_size)[index]; }

  public:

  bool sanitize (hb_sanitize_context_t *c, const void *base,

     unsigned int table_size) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        (valuesZ.sanitize (c, base, table_size))));

  }

  protected:

  F16DOT16  track;    /* Track value for this record. */

  NameID  trackNameID;  /* The 'name' table index for this track.

         * (a short word or phrase like "loose"

         * or "very tight") */

  NNOffset16To<UnsizedArrayOf<FWORD>>

    valuesZ;  /* Offset from start of tracking table to

         * per-size tracking values for this track. */

  public:

  DEFINE_SIZE_STATIC (8);

};

struct TrackData

{

  float interpolate_at (unsigned int idx,

      float target_size,

      const TrackTableEntry &trackTableEntry,

      const void *base) const

  {

    unsigned int sizes = nSizes;

    hb_array_t<const F16DOT16> size_table ((base+sizeTable).arrayZ, sizes);

    float s0 = size_table[idx].to_float ();

    float s1 = size_table[idx + 1].to_float ();

    float t = unlikely (s0 == s1) ? 0.f : (target_size - s0) / (s1 - s0);

    return t * trackTableEntry.get_value (base, idx + 1, sizes) +

     (1.f - t) * trackTableEntry.get_value (base, idx, sizes);

  }

  int get_tracking (const void *base, float ptem) const

  {

    /*

     * Choose track.

     */

    const TrackTableEntry *trackTableEntry = nullptr;

    unsigned int count = nTracks;

    for (unsigned int i = 0; i < count; i++)

    {

      /* Note: Seems like the track entries are sorted by values.  But the

       * spec doesn't explicitly say that.  It just mentions it in the example. */

      /* For now we only seek for track entries with zero tracking value */

      if (trackTable[i].get_track_value () == 0.f)

      {

  trackTableEntry = &trackTable[i];

  break;

      }

    }

    if (!trackTableEntry) return 0.;

    /*

     * Choose size.

     */

    unsigned int sizes = nSizes;

    if (!sizes) return 0.;

    if (sizes == 1) return trackTableEntry->get_value (base, 0, sizes);

    hb_array_t<const F16DOT16> size_table ((base+sizeTable).arrayZ, sizes);

    unsigned int size_index;

    for (size_index = 0; size_index < sizes - 1; size_index++)

      if (size_table[size_index].to_float () >= ptem)

  break;

    return roundf (interpolate_at (size_index ? size_index - 1 : 0, ptem,

           *trackTableEntry, base));

  }

  bool sanitize (hb_sanitize_context_t *c, const void *base) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        sizeTable.sanitize (c, base, nSizes) &&

        trackTable.sanitize (c, nTracks, base, nSizes)));

  }

  protected:

  HBUINT16  nTracks;  /* Number of separate tracks included in this table. */

  HBUINT16  nSizes;   /* Number of point sizes included in this table. */

  NNOffset32To<UnsizedArrayOf<F16DOT16>>

    sizeTable;  /* Offset from start of the tracking table to

         * Array[nSizes] of size values.. */

  UnsizedArrayOf<TrackTableEntry>

    trackTable; /* Array[nTracks] of TrackTableEntry records. */

  public:

  DEFINE_SIZE_ARRAY (8, trackTable);

};

struct trak

{

  static constexpr hb_tag_t tableTag = HB_AAT_TAG_trak;

  bool has_data () const { return version.to_int (); }

  bool apply (hb_aat_apply_context_t *c) const

  {

    TRACE_APPLY (this);

    hb_mask_t trak_mask = c->plan->trak_mask;

    const float ptem = c->font->ptem;

    if (unlikely (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;

      int tracking = trackData.get_tracking (this, ptem);

      hb_position_t offset_to_add = c->font->em_scalef_x (tracking / 2);

      hb_position_t advance_to_add = c->font->em_scalef_x (tracking);

      foreach_grapheme (buffer, start, end)

      {

  if (!(buffer->info[start].mask & trak_mask)) continue;

  buffer->pos[start].x_advance += advance_to_add;

  buffer->pos[start].x_offset += offset_to_add;

      }

    }

    else

    {

      const TrackData &trackData = this+vertData;

      int tracking = trackData.get_tracking (this, ptem);

      hb_position_t offset_to_add = c->font->em_scalef_y (tracking / 2);

      hb_position_t advance_to_add = c->font->em_scalef_y (tracking);

      foreach_grapheme (buffer, start, end)

      {

  if (!(buffer->info[start].mask & trak_mask)) continue;

  buffer->pos[start].y_advance += advance_to_add;

  buffer->pos[start].y_offset += offset_to_add;

      }

    }

    return_trace (true);

  }

  bool sanitize (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        version.major == 1 &&

        horizData.sanitize (c, this, this) &&

        vertData.sanitize (c, this, this)));

  }

  protected:

  FixedVersion<>version;  /* Version of the tracking table

         * (0x00010000u for version 1.0). */

  HBUINT16  format;   /* Format of the tracking table (set to 0). */

  Offset16To<TrackData>

    horizData;  /* Offset from start of tracking table to TrackData

         * for horizontal text (or 0 if none). */

  Offset16To<TrackData>

    vertData; /* Offset from start of tracking table to TrackData

         * for vertical text (or 0 if none). */

  HBUINT16  reserved; /* Reserved. Set to 0. */

  public:

  DEFINE_SIZE_STATIC (12);

};

} /* namespace AAT */

#endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */