src/hb-aat-layout-trak-table.hh - third_party/harfbuzz - Git at Google

 /*
  * 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:
   HBFixed	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") */
   NNOffsetTo<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 HBFixed> 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 HBFixed> 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. */
   LNNOffsetTo<UnsizedArrayOf<HBFixed>>
 		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). */
   OffsetTo<TrackData>
 		horizData;	/* Offset from start of tracking table to TrackData
 				 * for horizontal text (or 0 if none). */
   OffsetTo<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 */
	/*
	* 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:
	HBFixed 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") */
	NNOffsetTo<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 HBFixed> 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 HBFixed> 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. */
	LNNOffsetTo<UnsizedArrayOf<HBFixed>>
	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). */
	OffsetTo<TrackData>
	horizData; /* Offset from start of tracking table to TrackData
	* for horizontal text (or 0 if none). */
	OffsetTo<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 */