Roll HarfBuzz to 1.2.1

third_party/harfbuzz-ng/src/hb-directwrite.cc

Index: third_party/harfbuzz-ng/src/hb-directwrite.cc
diff --git a/third_party/harfbuzz-ng/src/hb-directwrite.cc b/third_party/harfbuzz-ng/src/hb-directwrite.cc
new file mode 100644
index 0000000000000000000000000000000000000000..af0fd3da0f77bfff1dd2eafaac13f7b121f92c5f
--- /dev/null
+++ b/third_party/harfbuzz-ng/src/hb-directwrite.cc
@@ -0,0 +1,827 @@
+/*
+ * Copyright © 2015  Ebrahim Byagowi
+ *
+ *  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.
+ */
+
+#define HB_SHAPER directwrite
+#include "hb-shaper-impl-private.hh"
+
+#include <dwrite.h>
+
+#include "hb-directwrite.h"
+
+#include "hb-open-file-private.hh"
+#include "hb-ot-name-table.hh"
+#include "hb-ot-tag.h"
+
+
+#ifndef HB_DEBUG_DIRECTWRITE
+#define HB_DEBUG_DIRECTWRITE (HB_DEBUG+0)
+#endif
+
+HB_SHAPER_DATA_ENSURE_DECLARE(directwrite, face)
+HB_SHAPER_DATA_ENSURE_DECLARE(directwrite, font)
+
+/*
+* shaper face data
+*/
+
+struct hb_directwrite_shaper_face_data_t {
+  HANDLE fh;
+  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);
+  ASSERT_STATIC (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 = OT::Sanitizer<OT::OpenTypeFontFile>::sanitize (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 name_table_offset = (length + 3) & ~3;
+
+  new_length = name_table_offset + ((name_table_length + 3) & ~3);
+  void *new_sfnt_data = calloc(1, new_length);
+  if (!new_sfnt_data)
+  {
+    hb_blob_destroy (blob);
+    return NULL;
+  }
+
+  memcpy(new_sfnt_data, orig_sfnt_data, length);
+
+  OT::name &name = OT::StructAtOffset<OT::name> (new_sfnt_data, name_table_offset);
+  name.format.set (0);
+  name.count.set (ARRAY_LENGTH (name_IDs));
+  name.stringOffset.set (name.get_size());
+  for (unsigned int i = 0; i < ARRAY_LENGTH (name_IDs); i++)
+  {
+    OT::NameRecord &record = name.nameRecord[i];
+    record.platformID.set(3);
+    record.encodingID.set(1);
+    record.languageID.set(0x0409u); /* English */
+    record.nameID.set(name_IDs[i]);
+    record.length.set(name_str_len * 2);
+    record.offset.set(0);
+  }
+
+  /* Copy string data from new_name, converting wchar_t to UTF16BE. */
+  unsigned char *p = &OT::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, name_table_length);
+      record.offset.set (name_table_offset);
+      record.length.set (name_table_length);
+    }
+    else if (face_index == 0) /* Fail if first face doesn't have 'name' table. */
+    {
+      free (new_sfnt_data);
+      hb_blob_destroy (blob);
+      return NULL;
+    }
+  }
+
+  /* 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, NULL, free);
+}
+
+hb_directwrite_shaper_face_data_t *
+_hb_directwrite_shaper_face_data_create(hb_face_t *face)
+{
+  hb_directwrite_shaper_face_data_t *data = (hb_directwrite_shaper_face_data_t *)calloc(1, sizeof (hb_directwrite_shaper_face_data_t));
+  if (unlikely (!data))
+    return NULL;
+
+  hb_blob_t *blob = hb_face_reference_blob (face);
+  if (unlikely (!hb_blob_get_length (blob)))
+    DEBUG_MSG(DIRECTWRITE, face, "Face has empty blob");
+
+  blob = _hb_rename_font (blob, data->face_name);
+  if (unlikely (!blob))
+  {
+    free(data);
+    return NULL;
+  }
+
+  DWORD num_fonts_installed;
+  data->fh = AddFontMemResourceEx ((void *)hb_blob_get_data(blob, NULL),
+    hb_blob_get_length (blob),
+    0, &num_fonts_installed);
+  if (unlikely (!data->fh))
+  {
+    DEBUG_MSG (DIRECTWRITE, face, "Face AddFontMemResourceEx() failed");
+    free (data);
+    return NULL;
+  }
+
+  return data;
+}
+
+void
+_hb_directwrite_shaper_face_data_destroy(hb_directwrite_shaper_face_data_t *data)
+{
+  RemoveFontMemResourceEx(data->fh);
+  free(data);
+}
+
+
+/*
+ * shaper font data
+ */
+
+struct hb_directwrite_shaper_font_data_t {
+  HDC hdc;
+  LOGFONTW log_font;
+  HFONT hfont;
+};
+
+static bool
+populate_log_font (LOGFONTW  *lf,
+       hb_font_t *font)
+{
+  memset (lf, 0, sizeof (*lf));
+  lf->lfHeight = -font->y_scale;
+  lf->lfCharSet = DEFAULT_CHARSET;
+
+  hb_face_t *face = font->face;
+  hb_directwrite_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+
+  memcpy (lf->lfFaceName, face_data->face_name, sizeof (lf->lfFaceName));
+
+  return true;
+}
+
+hb_directwrite_shaper_font_data_t *
+_hb_directwrite_shaper_font_data_create (hb_font_t *font)
+{
+  if (unlikely (!hb_directwrite_shaper_face_data_ensure (font->face))) return NULL;
+
+  hb_directwrite_shaper_font_data_t *data = (hb_directwrite_shaper_font_data_t *) calloc (1, sizeof (hb_directwrite_shaper_font_data_t));
+  if (unlikely (!data))
+    return NULL;
+
+  data->hdc = GetDC (NULL);
+
+  if (unlikely (!populate_log_font (&data->log_font, font))) {
+    DEBUG_MSG (DIRECTWRITE, font, "Font populate_log_font() failed");
+    _hb_directwrite_shaper_font_data_destroy (data);
+    return NULL;
+  }
+
+  data->hfont = CreateFontIndirectW (&data->log_font);
+  if (unlikely (!data->hfont)) {
+    DEBUG_MSG (DIRECTWRITE, font, "Font CreateFontIndirectW() failed");
+    _hb_directwrite_shaper_font_data_destroy (data);
+     return NULL;
+  }
+
+  if (!SelectObject (data->hdc, data->hfont)) {
+    DEBUG_MSG (DIRECTWRITE, font, "Font SelectObject() failed");
+    _hb_directwrite_shaper_font_data_destroy (data);
+     return NULL;
+  }
+
+  return data;
+}
+
+void
+_hb_directwrite_shaper_font_data_destroy (hb_directwrite_shaper_font_data_t *data)
+{
+  if (data->hdc)
+    ReleaseDC (NULL, data->hdc);
+  if (data->hfont)
+    DeleteObject (data->hfont);
+  free (data);
+}
+
+LOGFONTW *
+hb_directwrite_font_get_logfontw (hb_font_t *font)
+{
+  if (unlikely (!hb_directwrite_shaper_font_data_ensure (font))) return NULL;
+  hb_directwrite_shaper_font_data_t *font_data =  HB_SHAPER_DATA_GET (font);
+  return &font_data->log_font;
+}
+
+HFONT
+hb_directwrite_font_get_hfont (hb_font_t *font)
+{
+  if (unlikely (!hb_directwrite_shaper_font_data_ensure (font))) return NULL;
+  hb_directwrite_shaper_font_data_t *font_data =  HB_SHAPER_DATA_GET (font);
+  return font_data->hfont;
+}
+
+
+/*
+ * shaper shape_plan data
+ */
+
+struct hb_directwrite_shaper_shape_plan_data_t {};
+
+hb_directwrite_shaper_shape_plan_data_t *
+_hb_directwrite_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
+               const hb_feature_t *user_features HB_UNUSED,
+               unsigned int        num_user_features HB_UNUSED)
+{
+  return (hb_directwrite_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
+}
+
+void
+_hb_directwrite_shaper_shape_plan_data_destroy (hb_directwrite_shaper_shape_plan_data_t *data HB_UNUSED)
+{
+}
+
+// Most of here TextAnalysis is originally written by Bas Schouten for Mozilla project
+// but now is relicensed to MIT for HarfBuzz use
+class TextAnalysis
+  : public IDWriteTextAnalysisSource, public IDWriteTextAnalysisSink
+{
+public:
+
+  IFACEMETHOD(QueryInterface)(IID const& iid, OUT void** ppObject) { return S_OK; }
+  IFACEMETHOD_(ULONG, AddRef)() { return 1; }
+  IFACEMETHOD_(ULONG, Release)() { return 1; }
+
+  // A single contiguous run of characters containing the same analysis 
+  // results.
+  struct Run
+  {
+    UINT32 mTextStart;   // starting text position of this run
+    UINT32 mTextLength;  // number of contiguous code units covered
+    UINT32 mGlyphStart;  // starting glyph in the glyphs array
+    UINT32 mGlyphCount;  // number of glyphs associated with this run of 
+    // text
+    DWRITE_SCRIPT_ANALYSIS mScript;
+    UINT8 mBidiLevel;
+    bool mIsSideways;
+
+    inline bool ContainsTextPosition(UINT32 aTextPosition) const
+    {
+      return aTextPosition >= mTextStart
+        && aTextPosition <  mTextStart + mTextLength;
+    }
+
+    Run *nextRun;
+  };
+
+public:
+  TextAnalysis(const wchar_t* text,
+    UINT32 textLength,
+    const wchar_t* localeName,
+    DWRITE_READING_DIRECTION readingDirection)
+    : mText(text)
+    , mTextLength(textLength)
+    , mLocaleName(localeName)
+    , mReadingDirection(readingDirection)
+    , mCurrentRun(NULL) { };
+
+  ~TextAnalysis() {
+    // delete runs, except mRunHead which is part of the TextAnalysis object
+    for (Run *run = mRunHead.nextRun; run;) {
+      Run *origRun = run;
+      run = run->nextRun;
+      delete origRun;
+    }
+  }
+
+  STDMETHODIMP GenerateResults(IDWriteTextAnalyzer* textAnalyzer,
+    Run **runHead) {
+    // Analyzes the text using the script analyzer and returns
+    // the result as a series of runs.
+
+    HRESULT hr = S_OK;
+
+    // Initially start out with one result that covers the entire range.
+    // This result will be subdivided by the analysis processes.
+    mRunHead.mTextStart = 0;
+    mRunHead.mTextLength = mTextLength;
+    mRunHead.mBidiLevel =
+      (mReadingDirection == DWRITE_READING_DIRECTION_RIGHT_TO_LEFT);
+    mRunHead.nextRun = NULL;
+    mCurrentRun = &mRunHead;
+
+    // Call each of the analyzers in sequence, recording their results.
+    if (SUCCEEDED(hr = textAnalyzer->AnalyzeScript(this,
+      0,
+      mTextLength,
+      this))) {
+      *runHead = &mRunHead;
+    }
+
+    return hr;
+  }
+
+  // IDWriteTextAnalysisSource implementation
+
+  IFACEMETHODIMP GetTextAtPosition(UINT32 textPosition,
+    OUT WCHAR const** textString,
+    OUT UINT32* textLength)
+  {
+    if (textPosition >= mTextLength) {
+      // No text at this position, valid query though.
+      *textString = NULL;
+      *textLength = 0;
+    }
+    else {
+      *textString = mText + textPosition;
+      *textLength = mTextLength - textPosition;
+    }
+    return S_OK;
+  }
+
+  IFACEMETHODIMP GetTextBeforePosition(UINT32 textPosition,
+    OUT WCHAR const** textString,
+    OUT UINT32* textLength)
+  {
+    if (textPosition == 0 || textPosition > mTextLength) {
+      // Either there is no text before here (== 0), or this
+      // is an invalid position. The query is considered valid thouh.
+      *textString = NULL;
+      *textLength = 0;
+    }
+    else {
+      *textString = mText;
+      *textLength = textPosition;
+    }
+    return S_OK;
+  }
+
+  IFACEMETHODIMP_(DWRITE_READING_DIRECTION)
+    GetParagraphReadingDirection() { return mReadingDirection; }
+
+  IFACEMETHODIMP GetLocaleName(UINT32 textPosition,
+    UINT32* textLength,
+    WCHAR const** localeName) {
+    return S_OK;
+  }
+
+  IFACEMETHODIMP
+    GetNumberSubstitution(UINT32 textPosition,
+    OUT UINT32* textLength,
+    OUT IDWriteNumberSubstitution** numberSubstitution)
+  {
+    // We do not support number substitution.
+    *numberSubstitution = NULL;
+    *textLength = mTextLength - textPosition;
+
+    return S_OK;
+  }
+
+  // IDWriteTextAnalysisSink implementation
+
+  IFACEMETHODIMP
+    SetScriptAnalysis(UINT32 textPosition,
+    UINT32 textLength,
+    DWRITE_SCRIPT_ANALYSIS const* scriptAnalysis)
+  {
+    SetCurrentRun(textPosition);
+    SplitCurrentRun(textPosition);
+    while (textLength > 0) {
+      Run *run = FetchNextRun(&textLength);
+      run->mScript = *scriptAnalysis;
+    }
+
+    return S_OK;
+  }
+
+  IFACEMETHODIMP
+    SetLineBreakpoints(UINT32 textPosition,
+    UINT32 textLength,
+    const DWRITE_LINE_BREAKPOINT* lineBreakpoints) { return S_OK; }
+
+  IFACEMETHODIMP SetBidiLevel(UINT32 textPosition,
+    UINT32 textLength,
+    UINT8 explicitLevel,
+    UINT8 resolvedLevel) { return S_OK; }
+
+  IFACEMETHODIMP
+    SetNumberSubstitution(UINT32 textPosition,
+    UINT32 textLength,
+    IDWriteNumberSubstitution* numberSubstitution) { return S_OK; }
+
+protected:
+  Run *FetchNextRun(IN OUT UINT32* textLength)
+  {
+    // Used by the sink setters, this returns a reference to the next run.
+    // Position and length are adjusted to now point after the current run
+    // being returned.
+
+    Run *origRun = mCurrentRun;
+    // Split the tail if needed (the length remaining is less than the
+    // current run's size).
+    if (*textLength < mCurrentRun->mTextLength) {
+      SplitCurrentRun(mCurrentRun->mTextStart + *textLength);
+    }
+    else {
+      // Just advance the current run.
+      mCurrentRun = mCurrentRun->nextRun;
+    }
+    *textLength -= origRun->mTextLength;
+
+    // Return a reference to the run that was just current.
+    return origRun;
+  }
+
+  void SetCurrentRun(UINT32 textPosition)
+  {
+    // Move the current run to the given position.
+    // Since the analyzers generally return results in a forward manner,
+    // this will usually just return early. If not, find the
+    // corresponding run for the text position.
+
+    if (mCurrentRun && mCurrentRun->ContainsTextPosition(textPosition)) {
+      return;
+    }
+
+    for (Run *run = &mRunHead; run; run = run->nextRun) {
+      if (run->ContainsTextPosition(textPosition)) {
+        mCurrentRun = run;
+        return;
+      }
+    }
+    //NS_NOTREACHED("We should always be able to find the text position in one \
+            //                of our runs");
+  }
+
+  void SplitCurrentRun(UINT32 splitPosition)
+  {
+    if (!mCurrentRun) {
+      //NS_ASSERTION(false, "SplitCurrentRun called without current run.");
+      // Shouldn't be calling this when no current run is set!
+      return;
+    }
+    // Split the current run.
+    if (splitPosition <= mCurrentRun->mTextStart) {
+      // No need to split, already the start of a run
+      // or before it. Usually the first.
+      return;
+    }
+    Run *newRun = new Run;
+
+    *newRun = *mCurrentRun;
+
+    // Insert the new run in our linked list.
+    newRun->nextRun = mCurrentRun->nextRun;
+    mCurrentRun->nextRun = newRun;
+
+    // Adjust runs' text positions and lengths.
+    UINT32 splitPoint = splitPosition - mCurrentRun->mTextStart;
+    newRun->mTextStart += splitPoint;
+    newRun->mTextLength -= splitPoint;
+    mCurrentRun->mTextLength = splitPoint;
+    mCurrentRun = newRun;
+  }
+
+protected:
+  // Input
+  // (weak references are fine here, since this class is a transient
+  //  stack-based helper that doesn't need to copy data)
+  UINT32 mTextLength;
+  const WCHAR* mText;
+  const WCHAR* mLocaleName;
+  DWRITE_READING_DIRECTION mReadingDirection;
+
+  // Current processing state.
+  Run *mCurrentRun;
+
+  // Output is a list of runs starting here
+  Run  mRunHead;
+};
+
+
+/*
+ * shaper
+ */
+
+hb_bool_t
+_hb_directwrite_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;
+  hb_directwrite_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+  hb_directwrite_shaper_font_data_t *font_data = HB_SHAPER_DATA_GET (font);
+
+  // factory probably should be cached
+  IDWriteFactory* dwriteFactory;
+  DWriteCreateFactory(
+    DWRITE_FACTORY_TYPE_SHARED,
+    __uuidof(IDWriteFactory),
+    reinterpret_cast<IUnknown**>(&dwriteFactory)
+    );
+
+  IDWriteGdiInterop *gdiInterop;
+  dwriteFactory->GetGdiInterop (&gdiInterop);
+  IDWriteFontFace* fontFace;
+  gdiInterop->CreateFontFaceFromHdc (font_data->hdc, &fontFace);
+
+  IDWriteTextAnalyzer* analyzer;
+  dwriteFactory->CreateTextAnalyzer (&analyzer);
+
+  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; \
+  { \
+    unsigned int _consumed = DIV_CEIL ((len) * sizeof (Type), sizeof (*scratch)); \
+    assert (_consumed <= scratch_size); \
+    scratch += _consumed; \
+    scratch_size -= _consumed; \
+  }
+
+#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) & ((1 << 10) - 1));
+    }
+  }
+
+  ALLOCATE_ARRAY(WORD, log_clusters, 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. */
+    }
+  }
+
+  HRESULT hr;
+  // TODO: Handle TEST_DISABLE_OPTIONAL_LIGATURES
+
+  DWRITE_READING_DIRECTION readingDirection = buffer->props.direction ? 
+    DWRITE_READING_DIRECTION_RIGHT_TO_LEFT :
+    DWRITE_READING_DIRECTION_LEFT_TO_RIGHT;
+
+  /*
+  * There's an internal 16-bit limit on some things inside the analyzer,
+  * but we never attempt to shape a word longer than 64K characters
+  * in a single gfxShapedWord, so we cannot exceed that limit.
+  */
+  UINT32 length = buffer->len;
+
+  TextAnalysis analysis(pchars, length, NULL, readingDirection);
+  TextAnalysis::Run *runHead;
+  hr = analysis.GenerateResults(analyzer, &runHead);
+
+  if (FAILED(hr)) {
+    //NS_WARNING("Analyzer failed to generate results.");
+    return false;
+  }
+
+  UINT32 maxGlyphs = 3 * length / 2 + 16;
+
+#define INITIAL_GLYPH_SIZE 400
+  UINT16* clusters = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+  UINT16* glyphs = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+  DWRITE_SHAPING_TEXT_PROPERTIES* textProperties = (DWRITE_SHAPING_TEXT_PROPERTIES*)
+    malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_TEXT_PROPERTIES));
+  DWRITE_SHAPING_GLYPH_PROPERTIES* glyphProperties = (DWRITE_SHAPING_GLYPH_PROPERTIES*)
+    malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_GLYPH_PROPERTIES));
+
+  UINT32 actualGlyphs;
+
+  bool backward = HB_DIRECTION_IS_BACKWARD(buffer->props.direction);
+
+  wchar_t lang[4];
+  mbstowcs(lang, hb_language_to_string(buffer->props.language), 4);
+  hr = analyzer->GetGlyphs(pchars, length,
+    fontFace, FALSE,
+    buffer->props.direction,
+    &runHead->mScript, (const wchar_t*)lang, NULL, NULL, NULL, 0,
+    maxGlyphs, clusters, textProperties,
+    glyphs, glyphProperties, &actualGlyphs);
+
+  if (hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER)) {
+    free(clusters);
+    free(glyphs);
+    free(textProperties);
+    free(glyphProperties);
+
+    clusters = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+    glyphs = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+    textProperties = (DWRITE_SHAPING_TEXT_PROPERTIES*)
+      malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_TEXT_PROPERTIES));
+    glyphProperties = (DWRITE_SHAPING_GLYPH_PROPERTIES*)
+      malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_GLYPH_PROPERTIES));
+
+    hr = analyzer->GetGlyphs(pchars, length,
+      fontFace, FALSE,
+      buffer->props.direction,
+      &runHead->mScript, (const wchar_t*)lang, NULL, NULL, NULL, 0,
+      maxGlyphs, clusters, textProperties,
+      glyphs, glyphProperties, &actualGlyphs);
+  }
+  if (FAILED(hr)) {
+    //NS_WARNING("Analyzer failed to get glyphs.");
+    return false;
+  }
+
+  FLOAT advances[400];
+  DWRITE_GLYPH_OFFSET offsets[400];
+
+
+  /* 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) +
+    4 + // sizeof (SCRIPT_GLYPHPROP) +
+    sizeof (int) +
+    8 + // sizeof (GOFFSET) +
+    sizeof (uint32_t));
+  ALLOCATE_ARRAY(uint32_t, vis_clusters, glyphs_size);
+
+#undef ALLOCATE_ARRAY
+
+  hr = analyzer->GetGlyphPlacements(pchars,
+    clusters,
+    textProperties,
+    length,
+    glyphs,
+    glyphProperties,
+    actualGlyphs,
+    fontFace,
+    face->get_upem(),
+    FALSE,
+    FALSE,
+    &runHead->mScript,
+    NULL,
+    NULL,
+    NULL,
+    0,
+    advances,
+    offsets);
+
+  if (FAILED(hr)) {
+    //NS_WARNING("Analyzer failed to get glyph placements.");
+    return false;
+  }
+
+  unsigned int glyphs_len = actualGlyphs;
+
+  /* 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] = -1;
+  for (unsigned int i = 0; i < buffer->len; i++) {
+    uint32_t *p = &vis_clusters[log_clusters[buffer->info[i].utf16_index()]];
+    //*p = MIN (*p, buffer->info[i].cluster);
+  }
+  for (unsigned int i = 1; i < glyphs_len; i++)
+    if (vis_clusters[i] == -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.u32 = offsets[i].ascenderOffset;
+    info->var2.u32 = -offsets[i].advanceOffset;
+  }
+
+  free(clusters);
+  free(glyphs);
+  free(textProperties);
+  free(glyphProperties);
+
+  /* Set glyph positions */
+  buffer->clear_positions ();
+  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 = info->mask;
+    pos->x_offset = backward ? -info->var1.u32 : info->var1.u32;
+    pos->y_offset = info->var2.u32;
+  }
+
+  if (backward)
+    hb_buffer_reverse (buffer);
+
+  /* Wow, done! */
+  return true;
+}