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-os2-table.hh"
 #include "hb-ot-var-hvar-table.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')


 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.set (num_hmetrics);

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

     return result;
   }

   bool subset (hb_subset_plan_t *plan) const
   {
     typename T::accelerator_t _mtx;
     _mtx.init (plan->source);

     /* All the trailing glyphs with the same advance can use one LongMetric
      * and just keep LSB */
     unsigned int num_output_glyphs = plan->num_output_glyphs ();
     unsigned int num_advances = _mtx.num_advances_for_subset (plan);

     /* alloc the new table */
     size_t dest_sz = num_advances * 4
 		  + (num_output_glyphs - num_advances) * 2;
     void *dest = (void *) malloc (dest_sz);
     if (unlikely (!dest))
     {
       return false;
     }
     DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in src has %d advances, %d lsbs", HB_UNTAG(T::tableTag), _mtx.num_advances, _mtx.num_metrics - _mtx.num_advances);
     DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in dest has %d advances, %d lsbs, %u bytes",
               HB_UNTAG(T::tableTag), num_advances, num_output_glyphs - num_advances, (unsigned int) dest_sz);

     // Copy everything over
     char * dest_pos = (char *) dest;

     bool failed = false;
     for (unsigned int i = 0; i < num_output_glyphs; i++)
     {
       unsigned int side_bearing = 0;
       unsigned int advance = 0;
       hb_codepoint_t old_gid;
       if (plan->old_gid_for_new_gid (i, &old_gid))
       {
         // Glyph is not an empty glyph so copy advance and side bearing
         // from the input font.
         side_bearing = _mtx.get_side_bearing (old_gid);
         advance = _mtx.get_advance (old_gid);
       }

       bool has_advance = i < num_advances;
       if (has_advance)
       {
         ((LongMetric *) dest_pos)->advance.set (advance);
         ((LongMetric *) dest_pos)->sb.set (side_bearing);
       }
       else
       {
         ((FWORD *) dest_pos)->set (side_bearing);
       }
       dest_pos += (has_advance ? 4 : 2);
     }
     _mtx.fini ();

     // Amend header num hmetrics
     if (failed || unlikely (!subset_update_header (plan, num_advances)))
     {
       free (dest);
       return false;
     }

     hb_blob_t *result = hb_blob_create ((const char *)dest,
                                         dest_sz,
                                         HB_MEMORY_MODE_READONLY,
                                         dest,
                                         free);
     bool success = plan->add_table (T::tableTag, result);
     hb_blob_destroy (result);
     return success;
   }

   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);

       bool got_font_extents = false;
       if (T::os2Tag != HB_TAG_NONE && face->table.OS2->is_typo_metrics ())
       {
 	ascender = abs (face->table.OS2->sTypoAscender);
 	descender = -abs (face->table.OS2->sTypoDescender);
 	line_gap = face->table.OS2->sTypoLineGap;
 	got_font_extents = (ascender | descender) != 0;
       }

       hb_blob_t *_hea_blob = hb_sanitize_context_t().reference_table<H> (face);
       const H *_hea_table = _hea_blob->as<H> ();
       num_advances = _hea_table->numberOfLongMetrics;
       if (!got_font_extents)
       {
 	ascender = abs (_hea_table->ascender);
 	descender = -abs (_hea_table->descender);
 	line_gap = _hea_table->lineGap;
 	got_font_extents = (ascender | descender) != 0;
       }
       hb_blob_destroy (_hea_blob);

       has_font_extents = got_font_extents;

       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 ();
     }

     /* TODO Add variations version. */
     unsigned 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];
     }

     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[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);
       if (likely (glyph < num_metrics))
       {
 	advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
       }
       return advance;
     }

     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);
     }

     public:
     bool has_font_extents;
     int ascender;
     int descender;
     int line_gap;

     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 hb_tag_t os2Tag = HB_OT_TAG_OS2;
 };
 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 hb_tag_t os2Tag = HB_TAG_NONE;
 };

 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-os2-table.hh"
	#include "hb-ot-var-hvar-table.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')


	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.set (num_hmetrics);

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

	return result;
	}

	bool subset (hb_subset_plan_t *plan) const
	{
	typename T::accelerator_t _mtx;
	_mtx.init (plan->source);

	/* All the trailing glyphs with the same advance can use one LongMetric
	* and just keep LSB */
	unsigned int num_output_glyphs = plan->num_output_glyphs ();
	unsigned int num_advances = _mtx.num_advances_for_subset (plan);

	/* alloc the new table */
	size_t dest_sz = num_advances * 4
	+ (num_output_glyphs - num_advances) * 2;
	void dest = (void ) malloc (dest_sz);
	if (unlikely (!dest))
	{
	return false;
	}
	DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in src has %d advances, %d lsbs", HB_UNTAG(T::tableTag), _mtx.num_advances, _mtx.num_metrics - _mtx.num_advances);
	DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in dest has %d advances, %d lsbs, %u bytes",
	HB_UNTAG(T::tableTag), num_advances, num_output_glyphs - num_advances, (unsigned int) dest_sz);

	// Copy everything over
	char * dest_pos = (char *) dest;

	bool failed = false;
	for (unsigned int i = 0; i < num_output_glyphs; i++)
	{
	unsigned int side_bearing = 0;
	unsigned int advance = 0;
	hb_codepoint_t old_gid;
	if (plan->old_gid_for_new_gid (i, &old_gid))
	{
	// Glyph is not an empty glyph so copy advance and side bearing
	// from the input font.
	side_bearing = _mtx.get_side_bearing (old_gid);
	advance = _mtx.get_advance (old_gid);
	}

	bool has_advance = i < num_advances;
	if (has_advance)
	{
	((LongMetric *) dest_pos)->advance.set (advance);
	((LongMetric *) dest_pos)->sb.set (side_bearing);
	}
	else
	{
	((FWORD *) dest_pos)->set (side_bearing);
	}
	dest_pos += (has_advance ? 4 : 2);
	}
	_mtx.fini ();

	// Amend header num hmetrics
	if (failed \|\| unlikely (!subset_update_header (plan, num_advances)))
	{
	free (dest);
	return false;
	}

	hb_blob_t result = hb_blob_create ((const char )dest,
	dest_sz,
	HB_MEMORY_MODE_READONLY,
	dest,
	free);
	bool success = plan->add_table (T::tableTag, result);
	hb_blob_destroy (result);
	return success;
	}

	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);

	bool got_font_extents = false;
	if (T::os2Tag != HB_TAG_NONE && face->table.OS2->is_typo_metrics ())
	{
	ascender = abs (face->table.OS2->sTypoAscender);
	descender = -abs (face->table.OS2->sTypoDescender);
	line_gap = face->table.OS2->sTypoLineGap;
	got_font_extents = (ascender \| descender) != 0;
	}

	hb_blob_t *_hea_blob = hb_sanitize_context_t().reference_table<H> (face);
	const H *_hea_table = _hea_blob->as<H> ();
	num_advances = _hea_table->numberOfLongMetrics;
	if (!got_font_extents)
	{
	ascender = abs (_hea_table->ascender);
	descender = -abs (_hea_table->descender);
	line_gap = _hea_table->lineGap;
	got_font_extents = (ascender \| descender) != 0;
	}
	hb_blob_destroy (_hea_blob);

	has_font_extents = got_font_extents;

	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 ();
	}

	/* TODO Add variations version. */
	unsigned 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];
	}

	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[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);
	if (likely (glyph < num_metrics))
	{
	advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
	}
	return advance;
	}

	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);
	}

	public:
	bool has_font_extents;
	int ascender;
	int descender;
	int line_gap;

	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 hb_tag_t os2Tag = HB_OT_TAG_OS2;
	};
	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 hb_tag_t os2Tag = HB_TAG_NONE;
	};

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

	} /* namespace OT */


	#endif /* HB_OT_HMTX_TABLE_HH */