Update freetype sources (2.6.2) in third party.

third_party/freetype2/src/src/autofit/hbshim.c

Index: third_party/freetype2/src/src/autofit/hbshim.c
diff --git a/third_party/freetype2/src/src/autofit/hbshim.c b/third_party/freetype2/src/src/autofit/hbshim.c
new file mode 100644
index 0000000000000000000000000000000000000000..7a45059c39060fe4cd4a62318387122e3b0e6f48
--- /dev/null
+++ b/third_party/freetype2/src/src/autofit/hbshim.c
@@ -0,0 +1,546 @@
+/***************************************************************************/
+/*                                                                         */
+/*  hbshim.c                                                               */
+/*                                                                         */
+/*    HarfBuzz interface for accessing OpenType features (body).           */
+/*                                                                         */
+/*  Copyright 2013-2015 by                                                 */
+/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
+/*                                                                         */
+/*  This file is part of the FreeType project, and may only be used,       */
+/*  modified, and distributed under the terms of the FreeType project      */
+/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
+/*  this file you indicate that you have read the license and              */
+/*  understand and accept it fully.                                        */
+/*                                                                         */
+/***************************************************************************/
+
+
+#include <ft2build.h>
+#include FT_FREETYPE_H
+#include "afglobal.h"
+#include "aftypes.h"
+#include "hbshim.h"
+
+#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
+
+
+  /*************************************************************************/
+  /*                                                                       */
+  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
+  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
+  /* messages during execution.                                            */
+  /*                                                                       */
+#undef  FT_COMPONENT
+#define FT_COMPONENT  trace_afharfbuzz
+
+
+  /*
+   * We use `sets' (in the HarfBuzz sense, which comes quite near to the
+   * usual mathematical meaning) to manage both lookups and glyph indices.
+   *
+   * 1. For each coverage, collect lookup IDs in a set.  Note that an
+   *    auto-hinter `coverage' is represented by one `feature', and a
+   *    feature consists of an arbitrary number of (font specific) `lookup's
+   *    that actually do the mapping job.  Please check the OpenType
+   *    specification for more details on features and lookups.
+   *
+   * 2. Create glyph ID sets from the corresponding lookup sets.
+   *
+   * 3. The glyph set corresponding to AF_COVERAGE_DEFAULT is computed
+   *    with all lookups specific to the OpenType script activated.  It
+   *    relies on the order of AF_DEFINE_STYLE_CLASS entries so that
+   *    special coverages (like `oldstyle figures') don't get overwritten.
+   *
+   */
+
+
+  /* load coverage tags */
+#undef  COVERAGE
+#define COVERAGE( name, NAME, description,             \
+                  tag1, tag2, tag3, tag4 )             \
+          static const hb_tag_t  name ## _coverage[] = \
+          {                                            \
+            HB_TAG( tag1, tag2, tag3, tag4 ),          \
+            HB_TAG_NONE                                \
+          };
+
+
+#include "afcover.h"
+
+
+  /* define mapping between coverage tags and AF_Coverage */
+#undef  COVERAGE
+#define COVERAGE( name, NAME, description, \
+                  tag1, tag2, tag3, tag4 ) \
+          name ## _coverage,
+
+
+  static const hb_tag_t*  coverages[] =
+  {
+#include "afcover.h"
+
+    NULL /* AF_COVERAGE_DEFAULT */
+  };
+
+
+  /* load HarfBuzz script tags */
+#undef  SCRIPT
+#define SCRIPT( s, S, d, h, sc1, sc2, sc3 )  h,
+
+
+  static const hb_script_t  scripts[] =
+  {
+#include "afscript.h"
+  };
+
+
+  FT_Error
+  af_get_coverage( AF_FaceGlobals  globals,
+                   AF_StyleClass   style_class,
+                   FT_UShort*      gstyles )
+  {
+    hb_face_t*  face;
+
+    hb_set_t*  gsub_lookups;  /* GSUB lookups for a given script */
+    hb_set_t*  gsub_glyphs;   /* glyphs covered by GSUB lookups  */
+    hb_set_t*  gpos_lookups;  /* GPOS lookups for a given script */
+    hb_set_t*  gpos_glyphs;   /* glyphs covered by GPOS lookups  */
+
+    hb_script_t      script;
+    const hb_tag_t*  coverage_tags;
+    hb_tag_t         script_tags[] = { HB_TAG_NONE,
+                                       HB_TAG_NONE,
+                                       HB_TAG_NONE,
+                                       HB_TAG_NONE };
+
+    hb_codepoint_t  idx;
+#ifdef FT_DEBUG_LEVEL_TRACE
+    int             count;
+#endif
+
+
+    if ( !globals || !style_class || !gstyles )
+      return FT_THROW( Invalid_Argument );
+
+    face = hb_font_get_face( globals->hb_font );
+
+    gsub_lookups = hb_set_create();
+    gsub_glyphs  = hb_set_create();
+    gpos_lookups = hb_set_create();
+    gpos_glyphs  = hb_set_create();
+
+    coverage_tags = coverages[style_class->coverage];
+    script        = scripts[style_class->script];
+
+    /* Convert a HarfBuzz script tag into the corresponding OpenType */
+    /* tag or tags -- some Indic scripts like Devanagari have an old */
+    /* and a new set of features.                                    */
+    hb_ot_tags_from_script( script,
+                            &script_tags[0],
+                            &script_tags[1] );
+
+    /* `hb_ot_tags_from_script' usually returns HB_OT_TAG_DEFAULT_SCRIPT */
+    /* as the second tag.  We change that to HB_TAG_NONE except for the  */
+    /* default script.                                                   */
+    if ( style_class->script == globals->module->default_script &&
+         style_class->coverage == AF_COVERAGE_DEFAULT           )
+    {
+      if ( script_tags[0] == HB_TAG_NONE )
+        script_tags[0] = HB_OT_TAG_DEFAULT_SCRIPT;
+      else
+      {
+        if ( script_tags[1] == HB_TAG_NONE )
+          script_tags[1] = HB_OT_TAG_DEFAULT_SCRIPT;
+        else if ( script_tags[1] != HB_OT_TAG_DEFAULT_SCRIPT )
+          script_tags[2] = HB_OT_TAG_DEFAULT_SCRIPT;
+      }
+    }
+    else
+    {
+      if ( script_tags[1] == HB_OT_TAG_DEFAULT_SCRIPT )
+        script_tags[1] = HB_TAG_NONE;
+    }
+
+    hb_ot_layout_collect_lookups( face,
+                                  HB_OT_TAG_GSUB,
+                                  script_tags,
+                                  NULL,
+                                  coverage_tags,
+                                  gsub_lookups );
+
+    if ( hb_set_is_empty( gsub_lookups ) )
+      goto Exit; /* nothing to do */
+
+    hb_ot_layout_collect_lookups( face,
+                                  HB_OT_TAG_GPOS,
+                                  script_tags,
+                                  NULL,
+                                  coverage_tags,
+                                  gpos_lookups );
+
+    FT_TRACE4(( "GSUB lookups (style `%s'):\n"
+                " ",
+                af_style_names[style_class->style] ));
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    count = 0;
+#endif
+
+    for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_lookups, &idx ); )
+    {
+#ifdef FT_DEBUG_LEVEL_TRACE
+      FT_TRACE4(( " %d", idx ));
+      count++;
+#endif
+
+      /* get output coverage of GSUB feature */
+      hb_ot_layout_lookup_collect_glyphs( face,
+                                          HB_OT_TAG_GSUB,
+                                          idx,
+                                          NULL,
+                                          NULL,
+                                          NULL,
+                                          gsub_glyphs );
+    }
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    if ( !count )
+      FT_TRACE4(( " (none)" ));
+    FT_TRACE4(( "\n\n" ));
+#endif
+
+    FT_TRACE4(( "GPOS lookups (style `%s'):\n"
+                " ",
+                af_style_names[style_class->style] ));
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    count = 0;
+#endif
+
+    for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gpos_lookups, &idx ); )
+    {
+#ifdef FT_DEBUG_LEVEL_TRACE
+      FT_TRACE4(( " %d", idx ));
+      count++;
+#endif
+
+      /* get input coverage of GPOS feature */
+      hb_ot_layout_lookup_collect_glyphs( face,
+                                          HB_OT_TAG_GPOS,
+                                          idx,
+                                          NULL,
+                                          gpos_glyphs,
+                                          NULL,
+                                          NULL );
+    }
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    if ( !count )
+      FT_TRACE4(( " (none)" ));
+    FT_TRACE4(( "\n\n" ));
+#endif
+
+    /*
+     * We now check whether we can construct blue zones, using glyphs
+     * covered by the feature only.  In case there is not a single zone
+     * (this is, not a single character is covered), we skip this coverage.
+     *
+     */
+    if ( style_class->coverage != AF_COVERAGE_DEFAULT )
+    {
+      AF_Blue_Stringset         bss = style_class->blue_stringset;
+      const AF_Blue_StringRec*  bs  = &af_blue_stringsets[bss];
+
+      FT_Bool  found = 0;
+
+
+      for ( ; bs->string != AF_BLUE_STRING_MAX; bs++ )
+      {
+        const char*  p = &af_blue_strings[bs->string];
+
+
+        while ( *p )
+        {
+          hb_codepoint_t  ch;
+
+
+          GET_UTF8_CHAR( ch, p );
+
+          for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_lookups,
+                                                         &idx ); )
+          {
+            hb_codepoint_t  gidx = FT_Get_Char_Index( globals->face, ch );
+
+
+            if ( hb_ot_layout_lookup_would_substitute( face, idx,
+                                                       &gidx, 1, 1 ) )
+            {
+              found = 1;
+              break;
+            }
+          }
+        }
+      }
+
+      if ( !found )
+      {
+        FT_TRACE4(( "  no blue characters found; style skipped\n" ));
+        goto Exit;
+      }
+    }
+
+    /*
+     * Various OpenType features might use the same glyphs at different
+     * vertical positions; for example, superscript and subscript glyphs
+     * could be the same.  However, the auto-hinter is completely
+     * agnostic of OpenType features after the feature analysis has been
+     * completed: The engine then simply receives a glyph index and returns a
+     * hinted and usually rendered glyph.
+     *
+     * Consider the superscript feature of font `pala.ttf': Some of the
+     * glyphs are `real', this is, they have a zero vertical offset, but
+     * most of them are small caps glyphs shifted up to the superscript
+     * position (this is, the `sups' feature is present in both the GSUB and
+     * GPOS tables).  The code for blue zones computation actually uses a
+     * feature's y offset so that the `real' glyphs get correct hints.  But
+     * later on it is impossible to decide whether a glyph index belongs to,
+     * say, the small caps or superscript feature.
+     *
+     * For this reason, we don't assign a style to a glyph if the current
+     * feature covers the glyph in both the GSUB and the GPOS tables.  This
+     * is quite a broad condition, assuming that
+     *
+     *   (a) glyphs that get used in multiple features are present in a
+     *       feature without vertical shift,
+     *
+     * and
+     *
+     *   (b) a feature's GPOS data really moves the glyph vertically.
+     *
+     * Not fulfilling condition (a) makes a font larger; it would also
+     * reduce the number of glyphs that could be addressed directly without
+     * using OpenType features, so this assumption is rather strong.
+     *
+     * Condition (b) is much weaker, and there might be glyphs which get
+     * missed.  However, the OpenType features we are going to handle are
+     * primarily located in GSUB, and HarfBuzz doesn't provide an API to
+     * directly get the necessary information from the GPOS table.  A
+     * possible solution might be to directly parse the GPOS table to find
+     * out whether a glyph gets shifted vertically, but this is something I
+     * would like to avoid if not really necessary.
+     *
+     * Note that we don't follow this logic for the default coverage.
+     * Complex scripts like Devanagari have mandatory GPOS features to
+     * position many glyph elements, using mark-to-base or mark-to-ligature
+     * tables; the number of glyphs missed due to condition (b) would be far
+     * too large.
+     *
+     */
+    if ( style_class->coverage != AF_COVERAGE_DEFAULT )
+      hb_set_subtract( gsub_glyphs, gpos_glyphs );
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    FT_TRACE4(( "  glyphs without GPOS data (`*' means already assigned)" ));
+    count = 0;
+#endif
+
+    for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_glyphs, &idx ); )
+    {
+#ifdef FT_DEBUG_LEVEL_TRACE
+      if ( !( count % 10 ) )
+        FT_TRACE4(( "\n"
+                    "   " ));
+
+      FT_TRACE4(( " %d", idx ));
+      count++;
+#endif
+
+      /* glyph indices returned by `hb_ot_layout_lookup_collect_glyphs' */
+      /* can be arbitrary: some fonts use fake indices for processing   */
+      /* internal to GSUB or GPOS, which is fully valid                 */
+      if ( idx >= (hb_codepoint_t)globals->glyph_count )
+        continue;
+
+      if ( gstyles[idx] == AF_STYLE_UNASSIGNED )
+        gstyles[idx] = (FT_UShort)style_class->style;
+#ifdef FT_DEBUG_LEVEL_TRACE
+      else
+        FT_TRACE4(( "*" ));
+#endif
+    }
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    if ( !count )
+      FT_TRACE4(( "\n"
+                  "    (none)" ));
+    FT_TRACE4(( "\n\n" ));
+#endif
+
+  Exit:
+    hb_set_destroy( gsub_lookups );
+    hb_set_destroy( gsub_glyphs  );
+    hb_set_destroy( gpos_lookups );
+    hb_set_destroy( gpos_glyphs  );
+
+    return FT_Err_Ok;
+  }
+
+
+  /* construct HarfBuzz features */
+#undef  COVERAGE
+#define COVERAGE( name, NAME, description,                \
+                  tag1, tag2, tag3, tag4 )                \
+          static const hb_feature_t  name ## _feature[] = \
+          {                                               \
+            {                                             \
+              HB_TAG( tag1, tag2, tag3, tag4 ),           \
+              1, 0, (unsigned int)-1                      \
+            }                                             \
+          };
+
+
+#include "afcover.h"
+
+
+  /* define mapping between HarfBuzz features and AF_Coverage */
+#undef  COVERAGE
+#define COVERAGE( name, NAME, description, \
+                  tag1, tag2, tag3, tag4 ) \
+          name ## _feature,
+
+
+  static const hb_feature_t*  features[] =
+  {
+#include "afcover.h"
+
+    NULL /* AF_COVERAGE_DEFAULT */
+  };
+
+
+  FT_Error
+  af_get_char_index( AF_StyleMetrics  metrics,
+                     FT_ULong         charcode,
+                     FT_ULong        *codepoint,
+                     FT_Long         *y_offset )
+  {
+    AF_StyleClass  style_class;
+
+    const hb_feature_t*  feature;
+
+    FT_ULong  in_idx, out_idx;
+
+
+    if ( !metrics )
+      return FT_THROW( Invalid_Argument );
+
+    in_idx = FT_Get_Char_Index( metrics->globals->face, charcode );
+
+    style_class = metrics->style_class;
+
+    feature = features[style_class->coverage];
+
+    if ( feature )
+    {
+      FT_Int  upem = (FT_Int)metrics->globals->face->units_per_EM;
+
+      hb_font_t*    font = metrics->globals->hb_font;
+      hb_buffer_t*  buf  = hb_buffer_create();
+
+      uint32_t  c = (uint32_t)charcode;
+
+      hb_glyph_info_t*      ginfo;
+      hb_glyph_position_t*  gpos;
+      unsigned int          gcount;
+
+
+      /* we shape at a size of units per EM; this means font units */
+      hb_font_set_scale( font, upem, upem );
+
+      /* XXX: is this sufficient for a single character of any script? */
+      hb_buffer_set_direction( buf, HB_DIRECTION_LTR );
+      hb_buffer_set_script( buf, scripts[style_class->script] );
+
+      /* we add one character to `buf' ... */
+      hb_buffer_add_utf32( buf, &c, 1, 0, 1 );
+
+      /* ... and apply one feature */
+      hb_shape( font, buf, feature, 1 );
+
+      ginfo = hb_buffer_get_glyph_infos( buf, &gcount );
+      gpos  = hb_buffer_get_glyph_positions( buf, &gcount );
+
+      out_idx = ginfo[0].codepoint;
+
+      /* getting the same index indicates no substitution,         */
+      /* which means that the glyph isn't available in the feature */
+      if ( in_idx == out_idx )
+      {
+        *codepoint = 0;
+        *y_offset  = 0;
+      }
+      else
+      {
+        *codepoint = out_idx;
+        *y_offset  = gpos[0].y_offset;
+      }
+
+      hb_buffer_destroy( buf );
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+      if ( gcount > 1 )
+        FT_TRACE1(( "af_get_char_index:"
+                    " input character mapped to multiple glyphs\n" ));
+#endif
+    }
+    else
+    {
+      *codepoint = in_idx;
+      *y_offset  = 0;
+    }
+
+    return FT_Err_Ok;
+  }
+
+
+#else /* !FT_CONFIG_OPTION_USE_HARFBUZZ */
+
+
+  FT_Error
+  af_get_coverage( AF_FaceGlobals  globals,
+                   AF_StyleClass   style_class,
+                   FT_UShort*      gstyles )
+  {
+    FT_UNUSED( globals );
+    FT_UNUSED( style_class );
+    FT_UNUSED( gstyles );
+
+    return FT_Err_Ok;
+  }
+
+
+  FT_Error
+  af_get_char_index( AF_StyleMetrics  metrics,
+                     FT_ULong         charcode,
+                     FT_ULong        *codepoint,
+                     FT_Long         *y_offset )
+  {
+    FT_Face  face;
+
+
+    if ( !metrics )
+      return FT_THROW( Invalid_Argument );
+
+    face = metrics->globals->face;
+
+    *codepoint = FT_Get_Char_Index( face, charcode );
+    *y_offset  = 0;
+
+    return FT_Err_Ok;
+  }
+
+
+#endif /* !FT_CONFIG_OPTION_USE_HARFBUZZ */
+
+
+/* END */