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"
 #include "hb-ot-stat-table.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 (); }

   float interpolate_at (unsigned int idx,
 			float ptem,
 			const void *base,
 			hb_array_t<const F16DOT16> size_table) const
   {
     const FWORD *values = (base+valuesZ).arrayZ;

     float s0 = size_table[idx].to_float ();
     float s1 = size_table[idx + 1].to_float ();
     int v0 = values[idx];
     int v1 = values[idx + 1];

     // Deal with font bugs.
     if (unlikely (s1 < s0))
     { hb_swap (s0, s1); hb_swap (v0, v1); }
     if (unlikely (ptem < s0)) return v0;
     if (unlikely (ptem > s1)) return v1;
     if (unlikely (s0 == s1)) return (v0 + v1) * 0.5f;

     float t = (ptem - s0) / (s1 - s0);
     return v0 + t * (v1 - v0);
   }

   float get_value (float ptem,
 		   const void *base,
 		   hb_array_t<const F16DOT16> size_table) const
   {
     const FWORD *values = (base+valuesZ).arrayZ;

     unsigned int n_sizes = size_table.length;

     /*
      * Choose size.
      */
     if (!n_sizes) return 0.f;
     if (n_sizes == 1) return values[0];

     // At least two entries.

     unsigned i;
     for (i = 0; i < n_sizes; i++)
       if (size_table[i].to_float () >= ptem)
 	break;

     // Boundary conditions.
     if (i == 0)       return values[0];
     if (i == n_sizes) return values[n_sizes - 1];

     // Exact match.
     if (size_table[i].to_float () == ptem) return values[i];

     // Interpolate.
     return interpolate_at (i - 1, ptem, base, size_table);
   }

   public:
   bool sanitize (hb_sanitize_context_t *c,
 		 const void *base,
 		 unsigned int n_sizes) const
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
 			  (valuesZ.sanitize (c, base, n_sizes))));
   }

   protected:
   F16DOT16	track;		/* Track value for this record. */
   OT::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 get_tracking (const void *base, float ptem, float track = 0.f) const
   {
     unsigned count = nTracks;
     hb_array_t<const F16DOT16> size_table = (base+sizeTable).as_array (nSizes);

     if (!count) return 0.f;
     if (count == 1) return trackTable[0].get_value (ptem, base, size_table);

     // At least two entries.

     unsigned i = 0;
     unsigned j = count - 1;

     // Find the two entries that track is between.
     while (i + 1 < count && trackTable[i + 1].get_track_value () <= track)
       i++;
     while (j > 0 && trackTable[j - 1].get_track_value () >= track)
       j--;

     // Exact match.
     if (i == j) return trackTable[i].get_value (ptem, base, size_table);

     // Interpolate.

     float t0 = trackTable[i].get_track_value ();
     float t1 = trackTable[j].get_track_value ();

     float t = (track - t0) / (t1 - t0);

     float a = trackTable[i].get_value (ptem, base, size_table);
     float b = trackTable[j].get_value (ptem, base, size_table);
     return a + t * (b - a);
   }

   bool sanitize (hb_sanitize_context_t *c, const void *base) const
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
 			  hb_barrier () &&
 			  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 (); }

   hb_position_t get_h_tracking (hb_font_t *font, float track = 0.f) const
   {
     float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
     return font->em_scalef_x ((this+horizData).get_tracking (this, ptem, track));
   }
   hb_position_t get_v_tracking (hb_font_t *font, float track = 0.f) const
   {
     float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
     return font->em_scalef_y ((this+vertData).get_tracking (this, ptem, track));
   }
   hb_position_t get_tracking (hb_font_t *font, hb_direction_t dir, float track = 0.f) const
   {
 #ifndef HB_NO_STYLE
     if (!font->face->table.STAT->has_data ())
       return 0;
     return HB_DIRECTION_IS_HORIZONTAL (dir) ?
       get_h_tracking (font, track) :
       get_v_tracking (font, track);
 #else
     return 0;
 #endif
   }

   bool apply (hb_aat_apply_context_t *c, float track = 0.f) const
   {
     TRACE_APPLY (this);

     float ptem = c->font->ptem;
     if (unlikely (ptem <= 0.f))
     {
       /* https://developer.apple.com/documentation/coretext/1508745-ctfontcreatewithgraphicsfont */
       ptem = HB_CORETEXT_DEFAULT_FONT_SIZE;
     }

     hb_buffer_t *buffer = c->buffer;
     if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
     {
       hb_position_t advance_to_add = get_h_tracking (c->font, track);
       foreach_grapheme (buffer, start, end)
 	buffer->pos[start].x_advance += advance_to_add;
     }
     else
     {
       hb_position_t advance_to_add = get_v_tracking (c->font, track);
       foreach_grapheme (buffer, start, end)
 	buffer->pos[start].y_advance += advance_to_add;
     }

     return_trace (true);
   }

   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);

     return_trace (likely (c->check_struct (this) &&
 			  hb_barrier () &&
 			  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 */
	/*
	* 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"
	#include "hb-ot-stat-table.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 (); }

	float interpolate_at (unsigned int idx,
	float ptem,
	const void *base,
	hb_array_t<const F16DOT16> size_table) const
	{
	const FWORD *values = (base+valuesZ).arrayZ;

	float s0 = size_table[idx].to_float ();
	float s1 = size_table[idx + 1].to_float ();
	int v0 = values[idx];
	int v1 = values[idx + 1];

	// Deal with font bugs.
	if (unlikely (s1 < s0))
	{ hb_swap (s0, s1); hb_swap (v0, v1); }
	if (unlikely (ptem < s0)) return v0;
	if (unlikely (ptem > s1)) return v1;
	if (unlikely (s0 == s1)) return (v0 + v1) * 0.5f;

	float t = (ptem - s0) / (s1 - s0);
	return v0 + t * (v1 - v0);
	}

	float get_value (float ptem,
	const void *base,
	hb_array_t<const F16DOT16> size_table) const
	{
	const FWORD *values = (base+valuesZ).arrayZ;

	unsigned int n_sizes = size_table.length;

	/*
	* Choose size.
	*/
	if (!n_sizes) return 0.f;
	if (n_sizes == 1) return values[0];

	// At least two entries.

	unsigned i;
	for (i = 0; i < n_sizes; i++)
	if (size_table[i].to_float () >= ptem)
	break;

	// Boundary conditions.
	if (i == 0) return values[0];
	if (i == n_sizes) return values[n_sizes - 1];

	// Exact match.
	if (size_table[i].to_float () == ptem) return values[i];

	// Interpolate.
	return interpolate_at (i - 1, ptem, base, size_table);
	}

	public:
	bool sanitize (hb_sanitize_context_t *c,
	const void *base,
	unsigned int n_sizes) const
	{
	TRACE_SANITIZE (this);
	return_trace (likely (c->check_struct (this) &&
	(valuesZ.sanitize (c, base, n_sizes))));
	}

	protected:
	F16DOT16 track; /* Track value for this record. */
	OT::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 get_tracking (const void *base, float ptem, float track = 0.f) const
	{
	unsigned count = nTracks;
	hb_array_t<const F16DOT16> size_table = (base+sizeTable).as_array (nSizes);

	if (!count) return 0.f;
	if (count == 1) return trackTable[0].get_value (ptem, base, size_table);

	// At least two entries.

	unsigned i = 0;
	unsigned j = count - 1;

	// Find the two entries that track is between.
	while (i + 1 < count && trackTable[i + 1].get_track_value () <= track)
	i++;
	while (j > 0 && trackTable[j - 1].get_track_value () >= track)
	j--;

	// Exact match.
	if (i == j) return trackTable[i].get_value (ptem, base, size_table);

	// Interpolate.

	float t0 = trackTable[i].get_track_value ();
	float t1 = trackTable[j].get_track_value ();

	float t = (track - t0) / (t1 - t0);

	float a = trackTable[i].get_value (ptem, base, size_table);
	float b = trackTable[j].get_value (ptem, base, size_table);
	return a + t * (b - a);
	}

	bool sanitize (hb_sanitize_context_t c, const void base) const
	{
	TRACE_SANITIZE (this);
	return_trace (likely (c->check_struct (this) &&
	hb_barrier () &&
	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 (); }

	hb_position_t get_h_tracking (hb_font_t *font, float track = 0.f) const
	{
	float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
	return font->em_scalef_x ((this+horizData).get_tracking (this, ptem, track));
	}
	hb_position_t get_v_tracking (hb_font_t *font, float track = 0.f) const
	{
	float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
	return font->em_scalef_y ((this+vertData).get_tracking (this, ptem, track));
	}
	hb_position_t get_tracking (hb_font_t *font, hb_direction_t dir, float track = 0.f) const
	{
	#ifndef HB_NO_STYLE
	if (!font->face->table.STAT->has_data ())
	return 0;
	return HB_DIRECTION_IS_HORIZONTAL (dir) ?
	get_h_tracking (font, track) :
	get_v_tracking (font, track);
	#else
	return 0;
	#endif
	}

	bool apply (hb_aat_apply_context_t *c, float track = 0.f) const
	{
	TRACE_APPLY (this);

	float ptem = c->font->ptem;
	if (unlikely (ptem <= 0.f))
	{
	/* https://developer.apple.com/documentation/coretext/1508745-ctfontcreatewithgraphicsfont */
	ptem = HB_CORETEXT_DEFAULT_FONT_SIZE;
	}

	hb_buffer_t *buffer = c->buffer;
	if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
	{
	hb_position_t advance_to_add = get_h_tracking (c->font, track);
	foreach_grapheme (buffer, start, end)
	buffer->pos[start].x_advance += advance_to_add;
	}
	else
	{
	hb_position_t advance_to_add = get_v_tracking (c->font, track);
	foreach_grapheme (buffer, start, end)
	buffer->pos[start].y_advance += advance_to_add;
	}

	return_trace (true);
	}

	bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);

	return_trace (likely (c->check_struct (this) &&
	hb_barrier () &&
	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 */