src/hb-ot-hmtx-table.hh - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2011,2012  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, Roderick Sheeter
  */

 #ifndef HB_OT_HMTX_TABLE_HH
 #define HB_OT_HMTX_TABLE_HH

 #include "hb-open-type.hh"
 #include "hb-ot-hhea-table.hh"
 #include "hb-ot-var-hvar-table.hh"
 #include "hb-ot-metrics.hh"

 /*
  * hmtx -- Horizontal Metrics
  * https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
  * vmtx -- Vertical Metrics
  * https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
  */
 #define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
 #define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')


 HB_INTERNAL int
 _glyf_get_side_bearing_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);

 HB_INTERNAL unsigned
 _glyf_get_advance_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);


 namespace OT {


 struct LongMetric
 {
   UFWORD	advance; /* Advance width/height. */
   FWORD		sb; /* Leading (left/top) side bearing. */
   public:
   DEFINE_SIZE_STATIC (4);
 };


 template <typename T, typename H>
 struct hmtxvmtx
 {
   bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
   {
     TRACE_SANITIZE (this);
     /* We don't check for anything specific here.  The users of the
      * struct do all the hard work... */
     return_trace (true);
   }


   bool subset_update_header (hb_subset_plan_t *plan,
 			     unsigned int num_hmetrics) const
   {
     hb_blob_t *src_blob = hb_sanitize_context_t ().reference_table<H> (plan->source, H::tableTag);
     hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail (src_blob);
     hb_blob_destroy (src_blob);

     if (unlikely (!dest_blob)) {
       return false;
     }

     unsigned int length;
     H *table = (H *) hb_blob_get_data (dest_blob, &length);
     table->numberOfLongMetrics = num_hmetrics;

     bool result = plan->add_table (H::tableTag, dest_blob);
     hb_blob_destroy (dest_blob);

     return result;
   }

   template<typename Iterator,
 	   hb_requires (hb_is_iterator (Iterator))>
   void serialize (hb_serialize_context_t *c,
 		  Iterator it,
 		  unsigned num_advances)
   {
     unsigned idx = 0;
     for (auto _ : it)
     {
       if (idx < num_advances)
       {
 	LongMetric lm;
 	lm.advance = _.first;
 	lm.sb = _.second;
 	if (unlikely (!c->embed<LongMetric> (&lm))) return;
       }
       else
       {
 	FWORD *sb = c->allocate_size<FWORD> (FWORD::static_size);
 	if (unlikely (!sb)) return;
 	*sb = _.second;
       }
       idx++;
     }
   }

   bool subset (hb_subset_context_t *c) const
   {
     TRACE_SUBSET (this);

     T *table_prime = c->serializer->start_embed <T> ();
     if (unlikely (!table_prime)) return_trace (false);

     accelerator_t _mtx;
     _mtx.init (c->plan->source);
     unsigned num_advances = _mtx.num_advances_for_subset (c->plan);

     auto it =
     + hb_range (c->plan->num_output_glyphs ())
     | hb_map ([c, &_mtx] (unsigned _)
 	      {
 		hb_codepoint_t old_gid;
 		if (!c->plan->old_gid_for_new_gid (_, &old_gid))
 		  return hb_pair (0u, 0);
 		return hb_pair (_mtx.get_advance (old_gid), _mtx.get_side_bearing (old_gid));
 	      })
     ;

     table_prime->serialize (c->serializer, it, num_advances);

     _mtx.fini ();

     if (unlikely (c->serializer->in_error ()))
       return_trace (false);

     // Amend header num hmetrics
     if (unlikely (!subset_update_header (c->plan, num_advances)))
       return_trace (false);

     return_trace (true);
   }

   struct accelerator_t
   {
     friend struct hmtxvmtx;

     void init (hb_face_t *face,
 	       unsigned int default_advance_ = 0)
     {
       default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);

       num_advances = T::is_horizontal ? face->table.hhea->numberOfLongMetrics : face->table.vhea->numberOfLongMetrics;

       table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);

       /* Cap num_metrics() and num_advances() based on table length. */
       unsigned int len = table.get_length ();
       if (unlikely (num_advances * 4 > len))
 	num_advances = len / 4;
       num_metrics = num_advances + (len - 4 * num_advances) / 2;

       /* We MUST set num_metrics to zero if num_advances is zero.
        * Our get_advance() depends on that. */
       if (unlikely (!num_advances))
       {
 	num_metrics = num_advances = 0;
 	table.destroy ();
 	table = hb_blob_get_empty ();
       }

       var_table = hb_sanitize_context_t ().reference_table<HVARVVAR> (face, T::variationsTag);
     }

     void fini ()
     {
       table.destroy ();
       var_table.destroy ();
     }

     int get_side_bearing (hb_codepoint_t glyph) const
     {
       if (glyph < num_advances)
 	return table->longMetricZ[glyph].sb;

       if (unlikely (glyph >= num_metrics))
 	return 0;

       const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_advances];
       return bearings[glyph - num_advances];
     }

     int get_side_bearing (hb_font_t *font, hb_codepoint_t glyph) const
     {
       int side_bearing = get_side_bearing (glyph);

 #ifndef HB_NO_VAR
       if (unlikely (glyph >= num_metrics) || !font->num_coords)
 	return side_bearing;

       if (var_table.get_length ())
 	return side_bearing + var_table->get_side_bearing_var (glyph, font->coords, font->num_coords); // TODO Optimize?!

       return _glyf_get_side_bearing_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
 #else
       return side_bearing;
 #endif
     }

     unsigned int get_advance (hb_codepoint_t glyph) const
     {
       if (unlikely (glyph >= num_metrics))
       {
 	/* If num_metrics is zero, it means we don't have the metrics table
 	 * for this direction: return default advance.  Otherwise, it means that the
 	 * glyph index is out of bound: return zero. */
 	if (num_metrics)
 	  return 0;
 	else
 	  return default_advance;
       }

       return table->longMetricZ[hb_min (glyph, (uint32_t) num_advances - 1)].advance;
     }

     unsigned int get_advance (hb_codepoint_t  glyph,
 			      hb_font_t      *font) const
     {
       unsigned int advance = get_advance (glyph);

 #ifndef HB_NO_VAR
       if (unlikely (glyph >= num_metrics) || !font->num_coords)
 	return advance;

       if (var_table.get_length ())
 	return advance + roundf (var_table->get_advance_var (glyph, font)); // TODO Optimize?!

       return _glyf_get_advance_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
 #else
       return advance;
 #endif
     }

     unsigned int num_advances_for_subset (const hb_subset_plan_t *plan) const
     {
       unsigned int num_advances = plan->num_output_glyphs ();
       unsigned int last_advance = _advance_for_new_gid (plan,
 							num_advances - 1);
       while (num_advances > 1 &&
 	     last_advance == _advance_for_new_gid (plan,
 						   num_advances - 2))
       {
 	num_advances--;
       }

       return num_advances;
     }

     private:
     unsigned int _advance_for_new_gid (const hb_subset_plan_t *plan,
 				       hb_codepoint_t new_gid) const
     {
       hb_codepoint_t old_gid;
       if (!plan->old_gid_for_new_gid (new_gid, &old_gid))
 	return 0;

       return get_advance (old_gid);
     }

     protected:
     unsigned int num_metrics;
     unsigned int num_advances;
     unsigned int default_advance;

     private:
     hb_blob_ptr_t<hmtxvmtx> table;
     hb_blob_ptr_t<HVARVVAR> var_table;
   };

   protected:
   UnsizedArrayOf<LongMetric>
 		longMetricZ;	/* Paired advance width and leading
 				 * bearing values for each glyph. The
 				 * value numOfHMetrics comes from
 				 * the 'hhea' table. If the font is
 				 * monospaced, only one entry need
 				 * be in the array, but that entry is
 				 * required. The last entry applies to
 				 * all subsequent glyphs. */
 /*UnsizedArrayOf<FWORD>	leadingBearingX;*/
 				/* Here the advance is assumed
 				 * to be the same as the advance
 				 * for the last entry above. The
 				 * number of entries in this array is
 				 * derived from numGlyphs (from 'maxp'
 				 * table) minus numberOfLongMetrics.
 				 * This generally is used with a run
 				 * of monospaced glyphs (e.g., Kanji
 				 * fonts or Courier fonts). Only one
 				 * run is allowed and it must be at
 				 * the end. This allows a monospaced
 				 * font to vary the side bearing
 				 * values for each glyph. */
   public:
   DEFINE_SIZE_ARRAY (0, longMetricZ);
 };

 struct hmtx : hmtxvmtx<hmtx, hhea> {
   static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
   static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
   static constexpr bool is_horizontal = true;
 };
 struct vmtx : hmtxvmtx<vmtx, vhea> {
   static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
   static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
   static constexpr bool is_horizontal = false;
 };

 struct hmtx_accelerator_t : hmtx::accelerator_t {};
 struct vmtx_accelerator_t : vmtx::accelerator_t {};

 } /* namespace OT */


 #endif /* HB_OT_HMTX_TABLE_HH */
	/*
	* Copyright © 2011,2012 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, Roderick Sheeter
	*/

	#ifndef HB_OT_HMTX_TABLE_HH
	#define HB_OT_HMTX_TABLE_HH

	#include "hb-open-type.hh"
	#include "hb-ot-hhea-table.hh"
	#include "hb-ot-var-hvar-table.hh"
	#include "hb-ot-metrics.hh"

	/*
	* hmtx -- Horizontal Metrics
	* https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
	* vmtx -- Vertical Metrics
	* https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
	*/
	#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
	#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')


	HB_INTERNAL int
	_glyf_get_side_bearing_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);

	HB_INTERNAL unsigned
	_glyf_get_advance_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);


	namespace OT {


	struct LongMetric
	{
	UFWORD advance; /* Advance width/height. */
	FWORD sb; /* Leading (left/top) side bearing. */
	public:
	DEFINE_SIZE_STATIC (4);
	};


	template <typename T, typename H>
	struct hmtxvmtx
	{
	bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
	{
	TRACE_SANITIZE (this);
	/* We don't check for anything specific here. The users of the
	* struct do all the hard work... */
	return_trace (true);
	}


	bool subset_update_header (hb_subset_plan_t *plan,
	unsigned int num_hmetrics) const
	{
	hb_blob_t *src_blob = hb_sanitize_context_t ().reference_table<H> (plan->source, H::tableTag);
	hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail (src_blob);
	hb_blob_destroy (src_blob);

	if (unlikely (!dest_blob)) {
	return false;
	}

	unsigned int length;
	H table = (H ) hb_blob_get_data (dest_blob, &length);
	table->numberOfLongMetrics = num_hmetrics;

	bool result = plan->add_table (H::tableTag, dest_blob);
	hb_blob_destroy (dest_blob);

	return result;
	}

	template<typename Iterator,
	hb_requires (hb_is_iterator (Iterator))>
	void serialize (hb_serialize_context_t *c,
	Iterator it,
	unsigned num_advances)
	{
	unsigned idx = 0;
	for (auto _ : it)
	{
	if (idx < num_advances)
	{
	LongMetric lm;
	lm.advance = _.first;
	lm.sb = _.second;
	if (unlikely (!c->embed<LongMetric> (&lm))) return;
	}
	else
	{
	FWORD *sb = c->allocate_size<FWORD> (FWORD::static_size);
	if (unlikely (!sb)) return;
	*sb = _.second;
	}
	idx++;
	}
	}

	bool subset (hb_subset_context_t *c) const
	{
	TRACE_SUBSET (this);

	T *table_prime = c->serializer->start_embed <T> ();
	if (unlikely (!table_prime)) return_trace (false);

	accelerator_t _mtx;
	_mtx.init (c->plan->source);
	unsigned num_advances = _mtx.num_advances_for_subset (c->plan);

	auto it =
	+ hb_range (c->plan->num_output_glyphs ())
	\| hb_map ([c, &_mtx] (unsigned _)
	{
	hb_codepoint_t old_gid;
	if (!c->plan->old_gid_for_new_gid (_, &old_gid))
	return hb_pair (0u, 0);
	return hb_pair (_mtx.get_advance (old_gid), _mtx.get_side_bearing (old_gid));
	})
	;

	table_prime->serialize (c->serializer, it, num_advances);

	_mtx.fini ();

	if (unlikely (c->serializer->in_error ()))
	return_trace (false);

	// Amend header num hmetrics
	if (unlikely (!subset_update_header (c->plan, num_advances)))
	return_trace (false);

	return_trace (true);
	}

	struct accelerator_t
	{
	friend struct hmtxvmtx;

	void init (hb_face_t *face,
	unsigned int default_advance_ = 0)
	{
	default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);

	num_advances = T::is_horizontal ? face->table.hhea->numberOfLongMetrics : face->table.vhea->numberOfLongMetrics;

	table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);

	/* Cap num_metrics() and num_advances() based on table length. */
	unsigned int len = table.get_length ();
	if (unlikely (num_advances * 4 > len))
	num_advances = len / 4;
	num_metrics = num_advances + (len - 4 * num_advances) / 2;

	/* We MUST set num_metrics to zero if num_advances is zero.
	* Our get_advance() depends on that. */
	if (unlikely (!num_advances))
	{
	num_metrics = num_advances = 0;
	table.destroy ();
	table = hb_blob_get_empty ();
	}

	var_table = hb_sanitize_context_t ().reference_table<HVARVVAR> (face, T::variationsTag);
	}

	void fini ()
	{
	table.destroy ();
	var_table.destroy ();
	}

	int get_side_bearing (hb_codepoint_t glyph) const
	{
	if (glyph < num_advances)
	return table->longMetricZ[glyph].sb;

	if (unlikely (glyph >= num_metrics))
	return 0;

	const FWORD bearings = (const FWORD ) &table->longMetricZ[num_advances];
	return bearings[glyph - num_advances];
	}

	int get_side_bearing (hb_font_t *font, hb_codepoint_t glyph) const
	{
	int side_bearing = get_side_bearing (glyph);

	#ifndef HB_NO_VAR
	if (unlikely (glyph >= num_metrics) \|\| !font->num_coords)
	return side_bearing;

	if (var_table.get_length ())
	return side_bearing + var_table->get_side_bearing_var (glyph, font->coords, font->num_coords); // TODO Optimize?!

	return _glyf_get_side_bearing_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
	#else
	return side_bearing;
	#endif
	}

	unsigned int get_advance (hb_codepoint_t glyph) const
	{
	if (unlikely (glyph >= num_metrics))
	{
	/* If num_metrics is zero, it means we don't have the metrics table
	* for this direction: return default advance. Otherwise, it means that the
	* glyph index is out of bound: return zero. */
	if (num_metrics)
	return 0;
	else
	return default_advance;
	}

	return table->longMetricZ[hb_min (glyph, (uint32_t) num_advances - 1)].advance;
	}

	unsigned int get_advance (hb_codepoint_t glyph,
	hb_font_t *font) const
	{
	unsigned int advance = get_advance (glyph);

	#ifndef HB_NO_VAR
	if (unlikely (glyph >= num_metrics) \|\| !font->num_coords)
	return advance;

	if (var_table.get_length ())
	return advance + roundf (var_table->get_advance_var (glyph, font)); // TODO Optimize?!

	return _glyf_get_advance_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
	#else
	return advance;
	#endif
	}

	unsigned int num_advances_for_subset (const hb_subset_plan_t *plan) const
	{
	unsigned int num_advances = plan->num_output_glyphs ();
	unsigned int last_advance = _advance_for_new_gid (plan,
	num_advances - 1);
	while (num_advances > 1 &&
	last_advance == _advance_for_new_gid (plan,
	num_advances - 2))
	{
	num_advances--;
	}

	return num_advances;
	}

	private:
	unsigned int _advance_for_new_gid (const hb_subset_plan_t *plan,
	hb_codepoint_t new_gid) const
	{
	hb_codepoint_t old_gid;
	if (!plan->old_gid_for_new_gid (new_gid, &old_gid))
	return 0;

	return get_advance (old_gid);
	}

	protected:
	unsigned int num_metrics;
	unsigned int num_advances;
	unsigned int default_advance;

	private:
	hb_blob_ptr_t<hmtxvmtx> table;
	hb_blob_ptr_t<HVARVVAR> var_table;
	};

	protected:
	UnsizedArrayOf<LongMetric>
	longMetricZ; /* Paired advance width and leading
	* bearing values for each glyph. The
	* value numOfHMetrics comes from
	* the 'hhea' table. If the font is
	* monospaced, only one entry need
	* be in the array, but that entry is
	* required. The last entry applies to
	* all subsequent glyphs. */
	/UnsizedArrayOf<FWORD> leadingBearingX;/
	/* Here the advance is assumed
	* to be the same as the advance
	* for the last entry above. The
	* number of entries in this array is
	* derived from numGlyphs (from 'maxp'
	* table) minus numberOfLongMetrics.
	* This generally is used with a run
	* of monospaced glyphs (e.g., Kanji
	* fonts or Courier fonts). Only one
	* run is allowed and it must be at
	* the end. This allows a monospaced
	* font to vary the side bearing
	* values for each glyph. */
	public:
	DEFINE_SIZE_ARRAY (0, longMetricZ);
	};

	struct hmtx : hmtxvmtx<hmtx, hhea> {
	static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
	static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
	static constexpr bool is_horizontal = true;
	};
	struct vmtx : hmtxvmtx<vmtx, vhea> {
	static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
	static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
	static constexpr bool is_horizontal = false;
	};

	struct hmtx_accelerator_t : hmtx::accelerator_t {};
	struct vmtx_accelerator_t : vmtx::accelerator_t {};

	} /* namespace OT */


	#endif /* HB_OT_HMTX_TABLE_HH */