tor-browser

hb-uniscribe.cc (25090B)

---

/*
* Copyright © 2011,2012,2013  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
*/

#include "hb.hh"

#ifdef HAVE_UNISCRIBE

#ifdef HB_NO_OT_TAG
#error "Cannot compile 'uniscribe' shaper with HB_NO_OT_TAG."
#endif

#include "hb-shaper-impl.hh"

#include <windows.h>
#include <usp10.h>
#include <rpc.h>

#ifndef E_NOT_SUFFICIENT_BUFFER
#define E_NOT_SUFFICIENT_BUFFER HRESULT_FROM_WIN32 (ERROR_INSUFFICIENT_BUFFER)
#endif

#include "hb-uniscribe.h"

#include "hb-ms-feature-ranges.hh"
#include "hb-open-file.hh"
#include "hb-ot-name-table.hh"
#include "hb-ot-layout.h"


/**
* SECTION:hb-uniscribe
* @title: hb-uniscribe
* @short_description: Windows integration
* @include: hb-uniscribe.h
*
* Functions for using HarfBuzz with Windows fonts.
**/

typedef HRESULT (WINAPI *SIOT) /*ScriptItemizeOpenType*/(
 const WCHAR *pwcInChars,
 int cInChars,
 int cMaxItems,
 const SCRIPT_CONTROL *psControl,
 const SCRIPT_STATE *psState,
 SCRIPT_ITEM *pItems,
 OPENTYPE_TAG *pScriptTags,
 int *pcItems
);

typedef HRESULT (WINAPI *SSOT) /*ScriptShapeOpenType*/(
 HDC hdc,
 SCRIPT_CACHE *psc,
 SCRIPT_ANALYSIS *psa,
 OPENTYPE_TAG tagScript,
 OPENTYPE_TAG tagLangSys,
 int *rcRangeChars,
 TEXTRANGE_PROPERTIES **rpRangeProperties,
 int cRanges,
 const WCHAR *pwcChars,
 int cChars,
 int cMaxGlyphs,
 WORD *pwLogClust,
 SCRIPT_CHARPROP *pCharProps,
 WORD *pwOutGlyphs,
 SCRIPT_GLYPHPROP *pOutGlyphProps,
 int *pcGlyphs
);

typedef HRESULT (WINAPI *SPOT) /*ScriptPlaceOpenType*/(
 HDC hdc,
 SCRIPT_CACHE *psc,
 SCRIPT_ANALYSIS *psa,
 OPENTYPE_TAG tagScript,
 OPENTYPE_TAG tagLangSys,
 int *rcRangeChars,
 TEXTRANGE_PROPERTIES **rpRangeProperties,
 int cRanges,
 const WCHAR *pwcChars,
 WORD *pwLogClust,
 SCRIPT_CHARPROP *pCharProps,
 int cChars,
 const WORD *pwGlyphs,
 const SCRIPT_GLYPHPROP *pGlyphProps,
 int cGlyphs,
 int *piAdvance,
 GOFFSET *pGoffset,
 ABC *pABC
);


/* Fallback implementations. */

static HRESULT WINAPI
hb_ScriptItemizeOpenType(
 const WCHAR *pwcInChars,
 int cInChars,
 int cMaxItems,
 const SCRIPT_CONTROL *psControl,
 const SCRIPT_STATE *psState,
 SCRIPT_ITEM *pItems,
 OPENTYPE_TAG *pScriptTags,
 int *pcItems
)
{
{
 return ScriptItemize (pwcInChars,
		cInChars,
		cMaxItems,
		psControl,
		psState,
		pItems,
		pcItems);
}
}

static HRESULT WINAPI
hb_ScriptShapeOpenType(
 HDC hdc,
 SCRIPT_CACHE *psc,
 SCRIPT_ANALYSIS *psa,
 OPENTYPE_TAG tagScript,
 OPENTYPE_TAG tagLangSys,
 int *rcRangeChars,
 TEXTRANGE_PROPERTIES **rpRangeProperties,
 int cRanges,
 const WCHAR *pwcChars,
 int cChars,
 int cMaxGlyphs,
 WORD *pwLogClust,
 SCRIPT_CHARPROP *pCharProps,
 WORD *pwOutGlyphs,
 SCRIPT_GLYPHPROP *pOutGlyphProps,
 int *pcGlyphs
)
{
 SCRIPT_VISATTR *psva = (SCRIPT_VISATTR *) pOutGlyphProps;
 return ScriptShape (hdc,
	      psc,
	      pwcChars,
	      cChars,
	      cMaxGlyphs,
	      psa,
	      pwOutGlyphs,
	      pwLogClust,
	      psva,
	      pcGlyphs);
}

static HRESULT WINAPI
hb_ScriptPlaceOpenType(
 HDC hdc,
 SCRIPT_CACHE *psc,
 SCRIPT_ANALYSIS *psa,
 OPENTYPE_TAG tagScript,
 OPENTYPE_TAG tagLangSys,
 int *rcRangeChars,
 TEXTRANGE_PROPERTIES **rpRangeProperties,
 int cRanges,
 const WCHAR *pwcChars,
 WORD *pwLogClust,
 SCRIPT_CHARPROP *pCharProps,
 int cChars,
 const WORD *pwGlyphs,
 const SCRIPT_GLYPHPROP *pGlyphProps,
 int cGlyphs,
 int *piAdvance,
 GOFFSET *pGoffset,
 ABC *pABC
)
{
 SCRIPT_VISATTR *psva = (SCRIPT_VISATTR *) pGlyphProps;
 return ScriptPlace (hdc,
	      psc,
	      pwGlyphs,
	      cGlyphs,
	      psva,
	      psa,
	      piAdvance,
	      pGoffset,
	      pABC);
}


struct hb_uniscribe_shaper_funcs_t
{
 SIOT ScriptItemizeOpenType;
 SSOT ScriptShapeOpenType;
 SPOT ScriptPlaceOpenType;

 void init ()
 {
   HMODULE hinstLib;
   this->ScriptItemizeOpenType = nullptr;
   this->ScriptShapeOpenType   = nullptr;
   this->ScriptPlaceOpenType   = nullptr;

   hinstLib = GetModuleHandle (TEXT ("usp10.dll"));
   if (hinstLib)
   {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-function-type"
     this->ScriptItemizeOpenType = (SIOT) GetProcAddress (hinstLib, "ScriptItemizeOpenType");
     this->ScriptShapeOpenType   = (SSOT) GetProcAddress (hinstLib, "ScriptShapeOpenType");
     this->ScriptPlaceOpenType   = (SPOT) GetProcAddress (hinstLib, "ScriptPlaceOpenType");
#pragma GCC diagnostic pop
   }
   if (!this->ScriptItemizeOpenType ||
!this->ScriptShapeOpenType   ||
!this->ScriptPlaceOpenType)
   {
     DEBUG_MSG (UNISCRIBE, nullptr, "OpenType versions of functions not found; falling back.");
     this->ScriptItemizeOpenType = hb_ScriptItemizeOpenType;
     this->ScriptShapeOpenType   = hb_ScriptShapeOpenType;
     this->ScriptPlaceOpenType   = hb_ScriptPlaceOpenType;
   }
 }
};

static inline void free_static_uniscribe_shaper_funcs ();

static struct hb_uniscribe_shaper_funcs_lazy_loader_t : hb_lazy_loader_t<hb_uniscribe_shaper_funcs_t,
								 hb_uniscribe_shaper_funcs_lazy_loader_t>
{
 static hb_uniscribe_shaper_funcs_t *create ()
 {
   hb_uniscribe_shaper_funcs_t *funcs = (hb_uniscribe_shaper_funcs_t *) hb_calloc (1, sizeof (hb_uniscribe_shaper_funcs_t));
   if (unlikely (!funcs))
     return nullptr;

   funcs->init ();

   hb_atexit (free_static_uniscribe_shaper_funcs);

   return funcs;
 }
 static void destroy (hb_uniscribe_shaper_funcs_t *p)
 {
   hb_free ((void *) p);
 }
 static hb_uniscribe_shaper_funcs_t *get_null ()
 {
   return nullptr;
 }
} static_uniscribe_shaper_funcs;

static inline
void free_static_uniscribe_shaper_funcs ()
{
 static_uniscribe_shaper_funcs.free_instance ();
}

static hb_uniscribe_shaper_funcs_t *
hb_uniscribe_shaper_get_funcs ()
{
 return static_uniscribe_shaper_funcs.get_unconst ();
}


/*
* shaper face data
*/

struct hb_uniscribe_face_data_t {
 HANDLE fh;
 hb_uniscribe_shaper_funcs_t *funcs;
 wchar_t face_name[LF_FACESIZE];
};

/* face_name should point to a wchar_t[LF_FACESIZE] object. */
static void
_hb_generate_unique_face_name (wchar_t *face_name, unsigned int *plen)
{
 /* We'll create a private name for the font from a UUID using a simple,
  * somewhat base64-like encoding scheme */
 const char *enc = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-";
 UUID id;
 UuidCreate ((UUID*) &id);
 static_assert ((2 + 3 * (16/2) < LF_FACESIZE), "");
 unsigned int name_str_len = 0;
 face_name[name_str_len++] = 'F';
 face_name[name_str_len++] = '_';
 unsigned char *p = (unsigned char *) &id;
 for (unsigned int i = 0; i < 16; i += 2)
 {
   /* Spread the 16 bits from two bytes of the UUID across three chars of face_name,
    * using the bits in groups of 5,5,6 to select chars from enc.
    * This will generate 24 characters; with the 'F_' prefix we already provided,
    * the name will be 26 chars (plus the NUL terminator), so will always fit within
    * face_name (LF_FACESIZE = 32). */
   face_name[name_str_len++] = enc[p[i] >> 3];
   face_name[name_str_len++] = enc[((p[i] << 2) | (p[i + 1] >> 6)) & 0x1f];
   face_name[name_str_len++] = enc[p[i + 1] & 0x3f];
 }
 face_name[name_str_len] = 0;
 if (plen)
   *plen = name_str_len;
}

/* Destroys blob. */
static hb_blob_t *
_hb_rename_font (hb_blob_t *blob, wchar_t *new_name)
{
 /* Create a copy of the font data, with the 'name' table replaced by a
  * table that names the font with our private F_* name created above.
  * For simplicity, we just append a new 'name' table and update the
  * sfnt directory; the original table is left in place, but unused.
  *
  * The new table will contain just 5 name IDs: family, style, unique,
  * full, PS. All of them point to the same name data with our unique name.
  */

 blob = hb_sanitize_context_t ().sanitize_blob<OT::OpenTypeFontFile> (blob);

 unsigned int length, new_length, name_str_len;
 const char *orig_sfnt_data = hb_blob_get_data (blob, &length);

 _hb_generate_unique_face_name (new_name, &name_str_len);

 static const uint16_t name_IDs[] = { 1, 2, 3, 4, 6 };

 unsigned int name_table_length = OT::name::min_size +
			   ARRAY_LENGTH (name_IDs) * OT::NameRecord::static_size +
			   name_str_len * 2; /* for name data in UTF16BE form */
 unsigned int padded_name_table_length = ((name_table_length + 3) & ~3);
 unsigned int name_table_offset = (length + 3) & ~3;

 new_length = name_table_offset + padded_name_table_length;
 void *new_sfnt_data = hb_calloc (1, new_length);
 if (!new_sfnt_data)
 {
   hb_blob_destroy (blob);
   return nullptr;
 }

 hb_memcpy(new_sfnt_data, orig_sfnt_data, length);

 OT::name &name = StructAtOffset<OT::name> (new_sfnt_data, name_table_offset);
 name.format = 0;
 name.count = ARRAY_LENGTH (name_IDs);
 name.stringOffset = name.get_size ();
 for (unsigned int i = 0; i < ARRAY_LENGTH (name_IDs); i++)
 {
   OT::NameRecord &record = name.nameRecordZ[i];
   record.platformID = 3;
   record.encodingID = 1;
   record.languageID = 0x0409u; /* English */
   record.nameID = name_IDs[i];
   record.length = name_str_len * 2;
   record.offset = 0;
 }

 /* Copy string data from new_name, converting wchar_t to UTF16BE. */
 unsigned char *p = &StructAfter<unsigned char> (name);
 for (unsigned int i = 0; i < name_str_len; i++)
 {
   *p++ = new_name[i] >> 8;
   *p++ = new_name[i] & 0xff;
 }

 /* Adjust name table entry to point to new name table */
 const OT::OpenTypeFontFile &file = * (OT::OpenTypeFontFile *) (new_sfnt_data);
 unsigned int face_count = file.get_face_count ();
 for (unsigned int face_index = 0; face_index < face_count; face_index++)
 {
   /* Note: doing multiple edits (ie. TTC) can be unsafe.  There may be
    * toe-stepping.  But we don't really care. */
   const OT::OpenTypeFontFace &face = file.get_face (face_index);
   unsigned int index;
   if (face.find_table_index (HB_OT_TAG_name, &index))
   {
     OT::TableRecord &record = const_cast<OT::TableRecord &> (face.get_table (index));
     record.checkSum.set_for_data (&name, padded_name_table_length);
     record.offset = name_table_offset;
     record.length = name_table_length;
   }
   else if (face_index == 0) /* Fail if first face doesn't have 'name' table. */
   {
     hb_free (new_sfnt_data);
     hb_blob_destroy (blob);
     return nullptr;
   }
 }

 /* The checkSumAdjustment field in the 'head' table is now wrong,
  * but that doesn't actually seem to cause any problems so we don't
  * bother. */

 hb_blob_destroy (blob);
 return hb_blob_create ((const char *) new_sfnt_data, new_length,
		 HB_MEMORY_MODE_WRITABLE, new_sfnt_data, hb_free);
}

hb_uniscribe_face_data_t *
_hb_uniscribe_shaper_face_data_create (hb_face_t *face)
{
 hb_uniscribe_face_data_t *data = (hb_uniscribe_face_data_t *) hb_calloc (1, sizeof (hb_uniscribe_face_data_t));
 if (unlikely (!data))
   return nullptr;

 data->funcs = hb_uniscribe_shaper_get_funcs ();
 if (unlikely (!data->funcs))
 {
   hb_free (data);
   return nullptr;
 }

 hb_blob_t *blob = hb_face_reference_blob (face);
 if (unlikely (!hb_blob_get_length (blob)))
   DEBUG_MSG (UNISCRIBE, face, "Face has empty blob");

 blob = _hb_rename_font (blob, data->face_name);
 if (unlikely (!blob))
 {
   hb_free (data);
   return nullptr;
 }

 DWORD num_fonts_installed;
 data->fh = AddFontMemResourceEx ((void *) hb_blob_get_data (blob, nullptr),
			   hb_blob_get_length (blob),
			   0, &num_fonts_installed);
 if (unlikely (!data->fh))
 {
   DEBUG_MSG (UNISCRIBE, face, "Face AddFontMemResourceEx() failed");
   hb_free (data);
   return nullptr;
 }

 return data;
}

void
_hb_uniscribe_shaper_face_data_destroy (hb_uniscribe_face_data_t *data)
{
 RemoveFontMemResourceEx (data->fh);
 hb_free (data);
}


/*
* shaper font data
*/

struct hb_uniscribe_font_data_t
{
 HDC hdc;
 mutable LOGFONTW log_font;
 HFONT hfont;
 mutable SCRIPT_CACHE script_cache;
 double x_mult, y_mult; /* From LOGFONT space to HB space. */
};

static bool
populate_log_font (LOGFONTW  *lf,
	   hb_font_t *font,
	   unsigned int font_size)
{
 hb_memset (lf, 0, sizeof (*lf));
 lf->lfHeight = - (int) font_size;
 lf->lfCharSet = DEFAULT_CHARSET;

 hb_memcpy (lf->lfFaceName, font->face->data.uniscribe->face_name, sizeof (lf->lfFaceName));

 return true;
}

hb_uniscribe_font_data_t *
_hb_uniscribe_shaper_font_data_create (hb_font_t *font)
{
 hb_uniscribe_font_data_t *data = (hb_uniscribe_font_data_t *) hb_calloc (1, sizeof (hb_uniscribe_font_data_t));
 if (unlikely (!data))
   return nullptr;

 int font_size = font->face->get_upem (); /* Default... */
 /* No idea if the following is even a good idea. */
 if (font->y_ppem)
   font_size = font->y_ppem;

 if (font_size < 0)
   font_size = -font_size;
 data->x_mult = (double) font->x_scale / font_size;
 data->y_mult = (double) font->y_scale / font_size;

 data->hdc = GetDC (nullptr);

 if (unlikely (!populate_log_font (&data->log_font, font, font_size))) {
   DEBUG_MSG (UNISCRIBE, font, "Font populate_log_font() failed");
   _hb_uniscribe_shaper_font_data_destroy (data);
   return nullptr;
 }

 data->hfont = CreateFontIndirectW (&data->log_font);
 if (unlikely (!data->hfont)) {
   DEBUG_MSG (UNISCRIBE, font, "Font CreateFontIndirectW() failed");
   _hb_uniscribe_shaper_font_data_destroy (data);
    return nullptr;
 }

 if (!SelectObject (data->hdc, data->hfont)) {
   DEBUG_MSG (UNISCRIBE, font, "Font SelectObject() failed");
   _hb_uniscribe_shaper_font_data_destroy (data);
    return nullptr;
 }

 return data;
}

void
_hb_uniscribe_shaper_font_data_destroy (hb_uniscribe_font_data_t *data)
{
 if (data->hdc)
   ReleaseDC (nullptr, data->hdc);
 if (data->hfont)
   DeleteObject (data->hfont);
 if (data->script_cache)
   ScriptFreeCache (&data->script_cache);
 hb_free (data);
}

/**
* hb_uniscribe_font_get_logfontw:
* @font: The #hb_font_t to work upon
*
* Fetches the LOGFONTW structure that corresponds to the
* specified #hb_font_t font.
*
* Return value: a pointer to the LOGFONTW retrieved
*
**/
LOGFONTW *
hb_uniscribe_font_get_logfontw (hb_font_t *font)
{
 const hb_uniscribe_font_data_t *data =  font->data.uniscribe;
 return data ? &data->log_font : nullptr;
}

/**
* hb_uniscribe_font_get_hfont:
* @font: The #hb_font_t to work upon
*
* Fetches the HFONT handle that corresponds to the
* specified #hb_font_t font.
*
* Return value: the HFONT retreieved
*
**/
HFONT
hb_uniscribe_font_get_hfont (hb_font_t *font)
{
 const hb_uniscribe_font_data_t *data =  font->data.uniscribe;
 return data ? data->hfont : nullptr;
}


/*
* shaper
*/


hb_bool_t
_hb_uniscribe_shape (hb_shape_plan_t    *shape_plan,
	     hb_font_t          *font,
	     hb_buffer_t        *buffer,
	     const hb_feature_t *features,
	     unsigned int        num_features)
{
 hb_face_t *face = font->face;
 const hb_uniscribe_face_data_t *face_data = face->data.uniscribe;
 const hb_uniscribe_font_data_t *font_data = font->data.uniscribe;
 hb_uniscribe_shaper_funcs_t *funcs = face_data->funcs;

#define FAIL(...) \
 HB_STMT_START { \
   DEBUG_MSG (UNISCRIBE, nullptr, __VA_ARGS__); \
   return false; \
 } HB_STMT_END

 HRESULT hr;

retry:

 unsigned int scratch_size;
 hb_buffer_t::scratch_buffer_t *scratch = buffer->get_scratch_buffer (&scratch_size);

#define ALLOCATE_ARRAY(Type, name, len) \
 Type *name = (Type *) scratch; \
 do { \
   unsigned int _consumed = DIV_CEIL ((len) * sizeof (Type), sizeof (*scratch)); \
   assert (_consumed <= scratch_size); \
   scratch += _consumed; \
   scratch_size -= _consumed; \
 } while (0)

#define utf16_index() var1.u32

 ALLOCATE_ARRAY (WCHAR, pchars, buffer->len * 2);

 unsigned int chars_len = 0;
 for (unsigned int i = 0; i < buffer->len; i++)
 {
   hb_codepoint_t c = buffer->info[i].codepoint;
   buffer->info[i].utf16_index() = chars_len;
   if (likely (c <= 0xFFFFu))
     pchars[chars_len++] = c;
   else if (unlikely (c > 0x10FFFFu))
     pchars[chars_len++] = 0xFFFDu;
   else {
     pchars[chars_len++] = 0xD800u + ((c - 0x10000u) >> 10);
     pchars[chars_len++] = 0xDC00u + ((c - 0x10000u) & ((1u << 10) - 1));
   }
 }

 ALLOCATE_ARRAY (WORD, log_clusters, chars_len);
 ALLOCATE_ARRAY (SCRIPT_CHARPROP, char_props, chars_len);

 if (num_features)
 {
   /* Need log_clusters to assign features. */
   chars_len = 0;
   for (unsigned int i = 0; i < buffer->len; i++)
   {
     hb_codepoint_t c = buffer->info[i].codepoint;
     unsigned int cluster = buffer->info[i].cluster;
     log_clusters[chars_len++] = cluster;
     if (hb_in_range (c, 0x10000u, 0x10FFFFu))
log_clusters[chars_len++] = cluster; /* Surrogates. */
   }
 }

 /* The -2 in the following is to compensate for possible
  * alignment needed after the WORD array.  sizeof(WORD) == 2. */
 unsigned int glyphs_size = (scratch_size * sizeof (int) - 2)
		   / (sizeof (WORD) +
		      sizeof (SCRIPT_GLYPHPROP) +
		      sizeof (int) +
		      sizeof (GOFFSET) +
		      sizeof (uint32_t));

 ALLOCATE_ARRAY (WORD, glyphs, glyphs_size);
 ALLOCATE_ARRAY (SCRIPT_GLYPHPROP, glyph_props, glyphs_size);
 ALLOCATE_ARRAY (int, advances, glyphs_size);
 ALLOCATE_ARRAY (GOFFSET, offsets, glyphs_size);
 ALLOCATE_ARRAY (uint32_t, vis_clusters, glyphs_size);

 /* Note:
  * We can't touch the contents of glyph_props.  Our fallback
  * implementations of Shape and Place functions use that buffer
  * by casting it to a different type.  It works because they
  * both agree about it, but if we want to access it here we
  * need address that issue first.
  */

#undef ALLOCATE_ARRAY

#define MAX_ITEMS 256

 SCRIPT_ITEM items[MAX_ITEMS + 1];
 SCRIPT_CONTROL bidi_control = {0};
 SCRIPT_STATE bidi_state = {0};
 ULONG script_tags[MAX_ITEMS];
 int item_count;

 /* MinGW32 doesn't define fMergeNeutralItems, so we bruteforce */
 //bidi_control.fMergeNeutralItems = true;
 *(uint32_t*)&bidi_control |= 1u<<24;

 bidi_state.uBidiLevel = HB_DIRECTION_IS_FORWARD (buffer->props.direction) ? 0 : 1;
 bidi_state.fOverrideDirection = 1;

 hr = funcs->ScriptItemizeOpenType (pchars,
			     chars_len,
			     MAX_ITEMS,
			     &bidi_control,
			     &bidi_state,
			     items,
			     script_tags,
			     &item_count);
 if (unlikely (FAILED (hr)))
   FAIL ("ScriptItemizeOpenType() failed: 0x%08lx", (unsigned long) hr);

#undef MAX_ITEMS

 hb_tag_t lang_tag;
 unsigned int lang_count = 1;
 hb_ot_tags_from_script_and_language (buffer->props.script,
			       buffer->props.language,
			       nullptr, nullptr,
			       &lang_count, &lang_tag);
 OPENTYPE_TAG language_tag = hb_uint32_swap (lang_count ? lang_tag : HB_TAG_NONE);

 /*
  * Set up features.
  */
 static_assert ((sizeof (TEXTRANGE_PROPERTIES) == sizeof (hb_ms_features_t)), "");
 static_assert ((sizeof (OPENTYPE_FEATURE_RECORD) == sizeof (hb_ms_feature_t)), "");
 hb_vector_t<hb_ms_feature_t> feature_records;
 hb_vector_t<hb_ms_range_record_t> range_records;
 bool has_features = false;
 if (num_features)
   has_features = hb_ms_setup_features (features,
				 num_features,
				 feature_records,
				 range_records);

 hb_vector_t<hb_ms_features_t*> range_properties;
 hb_vector_t<uint32_t> range_char_counts;

 unsigned int glyphs_offset = 0;
 unsigned int glyphs_len;
 bool backward = HB_DIRECTION_IS_BACKWARD (buffer->props.direction);
 for (int i = 0; i < item_count; i++)
 {
   unsigned int chars_offset = items[i].iCharPos;
   unsigned int item_chars_len = items[i + 1].iCharPos - chars_offset;

   if (has_features)
     hb_ms_make_feature_ranges (feature_records,
			 range_records,
			 item_chars_len,
			 chars_offset,
			 log_clusters,
			 range_properties,
			 range_char_counts);

   /* Asking for glyphs in logical order circumvents at least
    * one bug in Uniscribe. */
   items[i].a.fLogicalOrder = true;

 retry_shape:
   hr = funcs->ScriptShapeOpenType (font_data->hdc,
			     &font_data->script_cache,
			     &items[i].a,
			     script_tags[i],
			     language_tag,
			     (int *) range_char_counts.arrayZ,
			     (TEXTRANGE_PROPERTIES**) range_properties.arrayZ,
			     range_properties.length,
			     pchars + chars_offset,
			     item_chars_len,
			     glyphs_size - glyphs_offset,
			     /* out */
			     log_clusters + chars_offset,
			     char_props + chars_offset,
			     glyphs + glyphs_offset,
			     glyph_props + glyphs_offset,
			     (int *) &glyphs_len);

   if (unlikely (items[i].a.fNoGlyphIndex))
     FAIL ("ScriptShapeOpenType() set fNoGlyphIndex");
   if (unlikely (hr == E_OUTOFMEMORY || hr == E_NOT_SUFFICIENT_BUFFER))
   {
     if (unlikely (!buffer->ensure (buffer->allocated * 2)))
FAIL ("Buffer resize failed");
     goto retry;
   }
   if (unlikely (hr == USP_E_SCRIPT_NOT_IN_FONT))
   {
     if (items[i].a.eScript == SCRIPT_UNDEFINED)
FAIL ("ScriptShapeOpenType() failed: Font doesn't support script");
     items[i].a.eScript = SCRIPT_UNDEFINED;
     goto retry_shape;
   }
   if (unlikely (FAILED (hr)))
   {
     FAIL ("ScriptShapeOpenType() failed: 0x%08lx", (unsigned long) hr);
   }

   for (unsigned int j = chars_offset; j < chars_offset + item_chars_len; j++)
     log_clusters[j] += glyphs_offset;

   hr = funcs->ScriptPlaceOpenType (font_data->hdc,
			     &font_data->script_cache,
			     &items[i].a,
			     script_tags[i],
			     language_tag,
			     (int *) range_char_counts.arrayZ,
			     (TEXTRANGE_PROPERTIES**) range_properties.arrayZ,
			     range_properties.length,
			     pchars + chars_offset,
			     log_clusters + chars_offset,
			     char_props + chars_offset,
			     item_chars_len,
			     glyphs + glyphs_offset,
			     glyph_props + glyphs_offset,
			     glyphs_len,
			     /* out */
			     advances + glyphs_offset,
			     offsets + glyphs_offset,
			     nullptr);
   if (unlikely (FAILED (hr)))
     FAIL ("ScriptPlaceOpenType() failed: 0x%08lx", (unsigned long) hr);

   if (DEBUG_ENABLED (UNISCRIBE))
     fprintf (stderr, "Item %d RTL %d LayoutRTL %d LogicalOrder %d ScriptTag %c%c%c%c\n",
       i,
       items[i].a.fRTL,
       items[i].a.fLayoutRTL,
       items[i].a.fLogicalOrder,
       HB_UNTAG (hb_uint32_swap (script_tags[i])));

   glyphs_offset += glyphs_len;
 }
 glyphs_len = glyphs_offset;

 /* Ok, we've got everything we need, now compose output buffer,
  * very, *very*, carefully! */

 /* Calculate visual-clusters.  That's what we ship. */
 for (unsigned int i = 0; i < glyphs_len; i++)
   vis_clusters[i] = (uint32_t) -1;
 for (unsigned int i = 0; i < buffer->len; i++) {
   uint32_t *p = &vis_clusters[log_clusters[buffer->info[i].utf16_index()]];
   *p = hb_min (*p, buffer->info[i].cluster);
 }
 for (unsigned int i = 1; i < glyphs_len; i++)
   if (vis_clusters[i] == (uint32_t) -1)
     vis_clusters[i] = vis_clusters[i - 1];

#undef utf16_index

 if (unlikely (!buffer->ensure (glyphs_len)))
   FAIL ("Buffer in error");

#undef FAIL

 /* Set glyph infos */
 buffer->len = 0;
 for (unsigned int i = 0; i < glyphs_len; i++)
 {
   hb_glyph_info_t *info = &buffer->info[buffer->len++];

   info->codepoint = glyphs[i];
   info->cluster = vis_clusters[i];

   /* The rest is crap.  Let's store position info there for now. */
   info->mask = advances[i];
   info->var1.i32 = offsets[i].du;
   info->var2.i32 = offsets[i].dv;
 }

 /* Set glyph positions */
 buffer->clear_positions ();
 double x_mult = font_data->x_mult, y_mult = font_data->y_mult;
 for (unsigned int i = 0; i < glyphs_len; i++)
 {
   hb_glyph_info_t *info = &buffer->info[i];
   hb_glyph_position_t *pos = &buffer->pos[i];

   /* TODO vertical */
   pos->x_advance = x_mult * (int32_t) info->mask;
   pos->x_offset = x_mult * (backward ? -info->var1.i32 : info->var1.i32);
   pos->y_offset = y_mult * info->var2.i32;
 }

 if (backward)
   hb_buffer_reverse (buffer);

 buffer->clear_glyph_flags ();
 buffer->unsafe_to_break ();

 /* Wow, done! */
 return true;
}


#endif