Merge pull request #239 from ebraminio/dwfix

Improve DirectWrite backend

src/hb-directwrite.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2015  Ebrahim Byagowi
+ * Copyright © 2015-2016  Ebrahim Byagowi
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
@@ -25,7 +25,11 @@
 #define HB_SHAPER directwrite
 #include "hb-shaper-impl-private.hh"
 
-#include <dwrite.h>
+#ifndef HB_DIRECTWRITE_EXPERIMENTAL_JUSTIFICATION
+  #include <DWrite.h>
+#else
+  #include <DWrite_1.h>
+#endif
 
 #include "hb-directwrite.h"
 
@@ -176,7 +180,8 @@ _hb_rename_font(hb_blob_t *blob, wchar_t *new_name)
 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));
+  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;
 
@@ -244,26 +249,30 @@ _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));
+  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))) {
+  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)) {
+  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)) {
+  if (!SelectObject (data->hdc, data->hfont))
+  {
     DEBUG_MSG (DIRECTWRITE, font, "Font SelectObject() failed");
     _hb_directwrite_shaper_font_data_destroy (data);
      return NULL;
@@ -333,16 +342,16 @@ public:
   // results.
   struct Run
   {
-    UINT32 mTextStart;   // starting text position of this run
+    uint32_t mTextStart;   // starting text position of this run
-    UINT32 mTextLength;  // number of contiguous code units covered
+    uint32_t mTextLength;  // number of contiguous code units covered
-    UINT32 mGlyphStart;  // starting glyph in the glyphs array
+    uint32_t mGlyphStart;  // starting glyph in the glyphs array
-    UINT32 mGlyphCount;  // number of glyphs associated with this run of 
+    uint32_t mGlyphCount;  // number of glyphs associated with this run of 
     // text
     DWRITE_SCRIPT_ANALYSIS mScript;
-    UINT8 mBidiLevel;
+    uint8_t mBidiLevel;
     bool mIsSideways;
 
-    inline bool ContainsTextPosition(UINT32 aTextPosition) const
+    inline bool ContainsTextPosition(uint32_t aTextPosition) const
     {
       return aTextPosition >= mTextStart
         && aTextPosition <  mTextStart + mTextLength;
@@ -353,7 +362,7 @@ public:
 
 public:
   TextAnalysis(const wchar_t* text,
-    UINT32 textLength,
+    uint32_t textLength,
     const wchar_t* localeName,
     DWRITE_READING_DIRECTION readingDirection)
     : mText(text)
@@ -367,7 +376,7 @@ public:
     for (Run *run = mRunHead.nextRun; run;) {
       Run *origRun = run;
       run = run->nextRun;
-      delete origRun;
+      free (origRun);
     }
   }
 
@@ -388,10 +397,7 @@ public:
     mCurrentRun = &mRunHead;
 
     // Call each of the analyzers in sequence, recording their results.
-    if (SUCCEEDED(hr = textAnalyzer->AnalyzeScript(this,
+    if (SUCCEEDED (hr = textAnalyzer->AnalyzeScript (this, 0, mTextLength, this))) {
-      0,
-      mTextLength,
-      this))) {
       *runHead = &mRunHead;
     }
 
@@ -400,9 +406,9 @@ public:
 
   // IDWriteTextAnalysisSource implementation
 
-  IFACEMETHODIMP GetTextAtPosition(UINT32 textPosition,
+  IFACEMETHODIMP GetTextAtPosition(uint32_t textPosition,
-    OUT WCHAR const** textString,
+    OUT wchar_t const** textString,
-    OUT UINT32* textLength)
+    OUT uint32_t* textLength)
   {
     if (textPosition >= mTextLength) {
       // No text at this position, valid query though.
@@ -416,9 +422,9 @@ public:
     return S_OK;
   }
 
-  IFACEMETHODIMP GetTextBeforePosition(UINT32 textPosition,
+  IFACEMETHODIMP GetTextBeforePosition(uint32_t textPosition,
-    OUT WCHAR const** textString,
+    OUT wchar_t const** textString,
-    OUT UINT32* textLength)
+    OUT uint32_t* textLength)
   {
     if (textPosition == 0 || textPosition > mTextLength) {
       // Either there is no text before here (== 0), or this
@@ -436,15 +442,15 @@ public:
   IFACEMETHODIMP_(DWRITE_READING_DIRECTION)
     GetParagraphReadingDirection() { return mReadingDirection; }
 
-  IFACEMETHODIMP GetLocaleName(UINT32 textPosition,
+  IFACEMETHODIMP GetLocaleName(uint32_t textPosition,
-    UINT32* textLength,
+    uint32_t* textLength,
-    WCHAR const** localeName) {
+    wchar_t const** localeName) {
     return S_OK;
   }
 
   IFACEMETHODIMP
-    GetNumberSubstitution(UINT32 textPosition,
+    GetNumberSubstitution(uint32_t textPosition,
-    OUT UINT32* textLength,
+    OUT uint32_t* textLength,
     OUT IDWriteNumberSubstitution** numberSubstitution)
   {
     // We do not support number substitution.
@@ -457,8 +463,8 @@ public:
   // IDWriteTextAnalysisSink implementation
 
   IFACEMETHODIMP
-    SetScriptAnalysis(UINT32 textPosition,
+    SetScriptAnalysis(uint32_t textPosition,
-    UINT32 textLength,
+    uint32_t textLength,
     DWRITE_SCRIPT_ANALYSIS const* scriptAnalysis)
   {
     SetCurrentRun(textPosition);
@@ -472,22 +478,22 @@ public:
   }
 
   IFACEMETHODIMP
-    SetLineBreakpoints(UINT32 textPosition,
+    SetLineBreakpoints(uint32_t textPosition,
-    UINT32 textLength,
+    uint32_t textLength,
     const DWRITE_LINE_BREAKPOINT* lineBreakpoints) { return S_OK; }
 
-  IFACEMETHODIMP SetBidiLevel(UINT32 textPosition,
+  IFACEMETHODIMP SetBidiLevel(uint32_t textPosition,
-    UINT32 textLength,
+    uint32_t textLength,
-    UINT8 explicitLevel,
+    uint8_t explicitLevel,
-    UINT8 resolvedLevel) { return S_OK; }
+    uint8_t resolvedLevel) { return S_OK; }
 
   IFACEMETHODIMP
-    SetNumberSubstitution(UINT32 textPosition,
+    SetNumberSubstitution(uint32_t textPosition,
-    UINT32 textLength,
+    uint32_t textLength,
     IDWriteNumberSubstitution* numberSubstitution) { return S_OK; }
 
 protected:
-  Run *FetchNextRun(IN OUT UINT32* textLength)
+  Run *FetchNextRun(IN OUT uint32_t* 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
@@ -509,7 +515,7 @@ protected:
     return origRun;
   }
 
-  void SetCurrentRun(UINT32 textPosition)
+  void SetCurrentRun(uint32_t textPosition)
   {
     // Move the current run to the given position.
     // Since the analyzers generally return results in a forward manner,
@@ -530,7 +536,7 @@ protected:
             //                of our runs");
   }
 
-  void SplitCurrentRun(UINT32 splitPosition)
+  void SplitCurrentRun(uint32_t splitPosition)
   {
     if (!mCurrentRun) {
       //NS_ASSERTION(false, "SplitCurrentRun called without current run.");
@@ -543,7 +549,7 @@ protected:
       // or before it. Usually the first.
       return;
     }
-    Run *newRun = new Run;
+    Run *newRun = (Run*) malloc (sizeof (Run));
 
     *newRun = *mCurrentRun;
 
@@ -552,7 +558,7 @@ protected:
     mCurrentRun->nextRun = newRun;
 
     // Adjust runs' text positions and lengths.
-    UINT32 splitPoint = splitPosition - mCurrentRun->mTextStart;
+    uint32_t splitPoint = splitPosition - mCurrentRun->mTextStart;
     newRun->mTextStart += splitPoint;
     newRun->mTextLength -= splitPoint;
     mCurrentRun->mTextLength = splitPoint;
@@ -563,9 +569,9 @@ 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;
+  uint32_t mTextLength;
-  const WCHAR* mText;
+  const wchar_t* mText;
-  const WCHAR* mLocaleName;
+  const wchar_t* mLocaleName;
   DWRITE_READING_DIRECTION mReadingDirection;
 
   // Current processing state.
@@ -575,6 +581,10 @@ protected:
   Run  mRunHead;
 };
 
+static inline uint16_t hb_uint16_swap (const uint16_t v)
+{ return (v >> 8) | (v << 8); }
+static inline uint32_t hb_uint32_swap (const uint32_t v)
+{ return (hb_uint16_swap(v) << 16) | hb_uint16_swap(v >> 16); }
 
 /*
  * shaper
@@ -592,20 +602,30 @@ _hb_directwrite_shape(hb_shape_plan_t    *shape_plan,
   hb_directwrite_shaper_font_data_t *font_data = HB_SHAPER_DATA_GET (font);
 
   // factory probably should be cached
+#ifndef HB_DIRECTWRITE_EXPERIMENTAL_JUSTIFICATION
   IDWriteFactory* dwriteFactory;
-  DWriteCreateFactory(
+#else
+  IDWriteFactory1* dwriteFactory;
+#endif
+  DWriteCreateFactory (
     DWRITE_FACTORY_TYPE_SHARED,
-    __uuidof(IDWriteFactory),
+    __uuidof (IDWriteFactory),
-    reinterpret_cast<IUnknown**>(&dwriteFactory)
+    (IUnknown**) &dwriteFactory
-    );
+  );
 
   IDWriteGdiInterop *gdiInterop;
   dwriteFactory->GetGdiInterop (&gdiInterop);
   IDWriteFontFace* fontFace;
   gdiInterop->CreateFontFaceFromHdc (font_data->hdc, &fontFace);
 
+#ifndef HB_DIRECTWRITE_EXPERIMENTAL_JUSTIFICATION
   IDWriteTextAnalyzer* analyzer;
-  dwriteFactory->CreateTextAnalyzer (&analyzer);
+  dwriteFactory->CreateTextAnalyzer(&analyzer);
+#else
+  IDWriteTextAnalyzer* analyzer0;
+  dwriteFactory->CreateTextAnalyzer (&analyzer0);
+  IDWriteTextAnalyzer1* analyzer = (IDWriteTextAnalyzer1*) analyzer0;
+#endif
 
   unsigned int scratch_size;
   hb_buffer_t::scratch_buffer_t *scratch = buffer->get_scratch_buffer (&scratch_size);
@@ -620,7 +640,7 @@ _hb_directwrite_shape(hb_shape_plan_t    *shape_plan,
 
 #define utf16_index() var1.u32
 
-  ALLOCATE_ARRAY(WCHAR, pchars, buffer->len * 2);
+  ALLOCATE_ARRAY(wchar_t, textString, buffer->len * 2);
 
   unsigned int chars_len = 0;
   for (unsigned int i = 0; i < buffer->len; i++)
@@ -628,17 +648,17 @@ _hb_directwrite_shape(hb_shape_plan_t    *shape_plan,
     hb_codepoint_t c = buffer->info[i].codepoint;
     buffer->info[i].utf16_index() = chars_len;
     if (likely(c <= 0xFFFFu))
-      pchars[chars_len++] = c;
+      textString[chars_len++] = c;
     else if (unlikely(c > 0x10FFFFu))
-      pchars[chars_len++] = 0xFFFDu;
+      textString[chars_len++] = 0xFFFDu;
     else {
-      pchars[chars_len++] = 0xD800u + ((c - 0x10000u) >> 10);
+      textString[chars_len++] = 0xD800u + ((c - 0x10000u) >> 10);
-      pchars[chars_len++] = 0xDC00u + ((c - 0x10000u) & ((1 << 10) - 1));
+      textString[chars_len++] = 0xDC00u + ((c - 0x10000u) & ((1 << 10) - 1));
     }
   }
 
   ALLOCATE_ARRAY(WORD, log_clusters, chars_len);
-  if (num_features)
+  // if (num_features)
   {
     /* Need log_clusters to assign features. */
     chars_len = 0;
@@ -664,164 +684,287 @@ _hb_directwrite_shape(hb_shape_plan_t    *shape_plan,
   * 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;
+  uint32_t textLength = buffer->len;
 
-  TextAnalysis analysis(pchars, length, NULL, readingDirection);
+  TextAnalysis analysis(textString, textLength, NULL, readingDirection);
   TextAnalysis::Run *runHead;
   hr = analysis.GenerateResults(analyzer, &runHead);
 
-  if (FAILED(hr)) {
+#define FAIL(...) \
-    //NS_WARNING("Analyzer failed to generate results.");
+  HB_STMT_START { \
+    DEBUG_MSG (DIRECTWRITE, NULL, __VA_ARGS__); \
+    return false; \
+  } HB_STMT_END;
+
+  if (FAILED (hr))
+  {
+    FAIL ("Analyzer failed to generate results.");
     return false;
   }
 
-  UINT32 maxGlyphs = 3 * length / 2 + 16;
+  uint32_t maxGlyphCount = 3 * textLength / 2 + 16;
+  uint32_t glyphCount;
+  bool isRightToLeft = HB_DIRECTION_IS_BACKWARD (buffer->props.direction);
+
+  const wchar_t localeName[20] = {0};
+  if (buffer->props.language != NULL)
+  {
+    mbstowcs ((wchar_t*) localeName,
+      hb_language_to_string (buffer->props.language), 20);
+  }
+
+  DWRITE_TYPOGRAPHIC_FEATURES singleFeatures;
+  singleFeatures.featureCount = num_features;
+  if (num_features)
+  {
+    DWRITE_FONT_FEATURE* dwfeatureArray = (DWRITE_FONT_FEATURE*)
+      malloc (sizeof (DWRITE_FONT_FEATURE) * num_features);
+    for (unsigned int i = 0; i < num_features; ++i)
+    {
+      dwfeatureArray[i].nameTag = (DWRITE_FONT_FEATURE_TAG)
+        hb_uint32_swap (features[i].tag);
+      dwfeatureArray[i].parameter = features[i].value;
+    }
+    singleFeatures.features = dwfeatureArray;
+  }
+  const DWRITE_TYPOGRAPHIC_FEATURES* dwFeatures =
+    (const DWRITE_TYPOGRAPHIC_FEATURES*) &singleFeatures;
+  const uint32_t featureRangeLengths[] = { textLength };
 
-#define INITIAL_GLYPH_SIZE 400
+retry_getglyphs:
-  UINT16* clusters = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+  uint16_t* clusterMap = (uint16_t*) malloc (maxGlyphCount * sizeof (uint16_t));
-  UINT16* glyphs = (UINT16*)malloc(INITIAL_GLYPH_SIZE * sizeof(UINT16));
+  uint16_t* glyphIndices = (uint16_t*) malloc (maxGlyphCount * sizeof (uint16_t));
   DWRITE_SHAPING_TEXT_PROPERTIES* textProperties = (DWRITE_SHAPING_TEXT_PROPERTIES*)
-    malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_TEXT_PROPERTIES));
+    malloc (maxGlyphCount * sizeof (DWRITE_SHAPING_TEXT_PROPERTIES));
   DWRITE_SHAPING_GLYPH_PROPERTIES* glyphProperties = (DWRITE_SHAPING_GLYPH_PROPERTIES*)
-    malloc(INITIAL_GLYPH_SIZE * sizeof(DWRITE_SHAPING_GLYPH_PROPERTIES));
+    malloc (maxGlyphCount * sizeof (DWRITE_SHAPING_GLYPH_PROPERTIES));
-
+
-  UINT32 actualGlyphs;
+  hr = analyzer->GetGlyphs (textString, textLength, fontFace, FALSE,
-
+    isRightToLeft, &runHead->mScript, localeName, NULL, &dwFeatures,
-  bool backward = HB_DIRECTION_IS_BACKWARD(buffer->props.direction);
+    featureRangeLengths, 1, maxGlyphCount, clusterMap, textProperties, glyphIndices,
-
+    glyphProperties, &glyphCount);
-  wchar_t lang[4];
+
-  mbstowcs(lang, hb_language_to_string(buffer->props.language), 4);
+  if (unlikely (hr == HRESULT_FROM_WIN32 (ERROR_INSUFFICIENT_BUFFER)))
-  hr = analyzer->GetGlyphs(pchars, length,
+  {
-    fontFace, FALSE,
+    free (clusterMap);
-    buffer->props.direction,
+    free (glyphIndices);
-    &runHead->mScript, (const wchar_t*)lang, NULL, NULL, NULL, 0,
+    free (textProperties);
-    maxGlyphs, clusters, textProperties,
+    free (glyphProperties);
-    glyphs, glyphProperties, &actualGlyphs);
+
-
+    maxGlyphCount *= 2;
-  if (hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER)) {
+
-    free(clusters);
+    goto retry_getglyphs;
-    free(glyphs);
+  }
-    free(textProperties);
+  if (FAILED (hr))
-    free(glyphProperties);
+  {
-
+    FAIL ("Analyzer failed to get glyphs.");
-    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];
+  float* glyphAdvances = (float*) malloc (maxGlyphCount * sizeof (float));
-  DWRITE_GLYPH_OFFSET offsets[400];
+  DWRITE_GLYPH_OFFSET* glyphOffsets = (DWRITE_GLYPH_OFFSET*)
-
+    malloc(maxGlyphCount * sizeof (DWRITE_GLYPH_OFFSET));
 
   /* 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)
+  unsigned int glyphs_size = (scratch_size * sizeof(int) - 2)
-    / (sizeof (WORD) +
+         / (sizeof(WORD) +
-    4 + // sizeof (SCRIPT_GLYPHPROP) +
+            sizeof(DWRITE_SHAPING_GLYPH_PROPERTIES) +
-    sizeof (int) +
+            sizeof(int) +
-    8 + // sizeof (GOFFSET) +
+            sizeof(DWRITE_GLYPH_OFFSET) +
-    sizeof (uint32_t));
+            sizeof(uint32_t));
-  ALLOCATE_ARRAY(uint32_t, vis_clusters, glyphs_size);
+  ALLOCATE_ARRAY (uint32_t, vis_clusters, glyphs_size);
 
 #undef ALLOCATE_ARRAY
 
-  hr = analyzer->GetGlyphPlacements(pchars,
+  int fontEmSize = font->face->get_upem();
-    clusters,
+  if (fontEmSize < 0)
-    textProperties,
+    fontEmSize = -fontEmSize;
-    length,
+
-    glyphs,
+  if (fontEmSize < 0)
-    glyphProperties,
+    fontEmSize = -fontEmSize;
-    actualGlyphs,
+  double x_mult = (double) font->x_scale / fontEmSize;
-    fontFace,
+  double y_mult = (double) font->y_scale / fontEmSize;
-    face->get_upem(),
+
-    FALSE,
+  hr = analyzer->GetGlyphPlacements (textString,
-    FALSE,
+    clusterMap, textProperties, textLength, glyphIndices,
-    &runHead->mScript,
+    glyphProperties, glyphCount, fontFace, fontEmSize,
-    NULL,
+    FALSE, isRightToLeft, &runHead->mScript, localeName,
-    NULL,
+    &dwFeatures, featureRangeLengths, 1,
-    NULL,
+    glyphAdvances, glyphOffsets);
-    0,
+
-    advances,
+  if (FAILED (hr))
-    offsets);
+  {
-
+    FAIL ("Analyzer failed to get glyph placements.");
-  if (FAILED(hr)) {
-    //NS_WARNING("Analyzer failed to get glyph placements.");
     return false;
   }
 
-  unsigned int glyphs_len = actualGlyphs;
+#ifdef HB_DIRECTWRITE_EXPERIMENTAL_JUSTIFICATION
+
+  DWRITE_JUSTIFICATION_OPPORTUNITY* justificationOpportunities =
+    (DWRITE_JUSTIFICATION_OPPORTUNITY*)
+    malloc (maxGlyphCount * sizeof (DWRITE_JUSTIFICATION_OPPORTUNITY));
+  hr = analyzer->GetJustificationOpportunities (fontFace, fontEmSize,
+    runHead->mScript, textLength, glyphCount, textString, clusterMap,
+    glyphProperties, justificationOpportunities);
+
+  if (FAILED (hr))
+  {
+    FAIL ("Analyzer failed to get justification opportunities.");
+    return false;
+  }
+
+  // TODO: get lineWith from somewhere
+  float lineWidth = 60000;
+
+  float* justifiedGlyphAdvances =
+    (float*) malloc (maxGlyphCount * sizeof (float));
+  DWRITE_GLYPH_OFFSET* justifiedGlyphOffsets = (DWRITE_GLYPH_OFFSET*)
+    malloc (glyphCount * sizeof (DWRITE_GLYPH_OFFSET));
+  hr = analyzer->JustifyGlyphAdvances (lineWidth, glyphCount, justificationOpportunities,
+    glyphAdvances, glyphOffsets, justifiedGlyphAdvances, justifiedGlyphOffsets);
+
+  if (FAILED (hr))
+  {
+    FAIL ("Analyzer failed to get justified glyph advances.");
+    return false;
+  }
+
+  DWRITE_SCRIPT_PROPERTIES scriptProperties;
+  hr = analyzer->GetScriptProperties (runHead->mScript, &scriptProperties);
+  if (FAILED (hr))
+  {
+    FAIL ("Analyzer failed to get script properties.");
+    return false;
+  }
+  uint32_t justificationCharacter = scriptProperties.justificationCharacter;
+
+  // if a script justificationCharacter is not space, it can have GetJustifiedGlyphs
+  if (justificationCharacter != 32)
+  {
+retry_getjustifiedglyphs:
+    uint16_t* modifiedClusterMap = (uint16_t*) malloc (maxGlyphCount * sizeof (uint16_t));
+    uint16_t* modifiedGlyphIndices = (uint16_t*) malloc (maxGlyphCount * sizeof (uint16_t));
+    float* modifiedGlyphAdvances = (float*) malloc (maxGlyphCount * sizeof (float));
+    DWRITE_GLYPH_OFFSET* modifiedGlyphOffsets = (DWRITE_GLYPH_OFFSET*)
+      malloc (maxGlyphCount * sizeof (DWRITE_GLYPH_OFFSET));
+    uint32_t actualGlyphsCount;
+    hr = analyzer->GetJustifiedGlyphs (fontFace, fontEmSize, runHead->mScript,
+        textLength, glyphCount, maxGlyphCount, clusterMap, glyphIndices,
+        glyphAdvances, justifiedGlyphAdvances, justifiedGlyphOffsets,
+        glyphProperties, &actualGlyphsCount, modifiedClusterMap, modifiedGlyphIndices,
+        modifiedGlyphAdvances, modifiedGlyphOffsets);
+
+    if (hr == HRESULT_FROM_WIN32 (ERROR_INSUFFICIENT_BUFFER))
+    {
+      maxGlyphCount = actualGlyphsCount;
+      free (modifiedClusterMap);
+      free (modifiedGlyphIndices);
+      free (modifiedGlyphAdvances);
+      free (modifiedGlyphOffsets);
+
+      maxGlyphCount = actualGlyphsCount;
+
+      goto retry_getjustifiedglyphs;
+    }
+    if (FAILED (hr))
+    {
+      FAIL ("Analyzer failed to get justified glyphs.");
+      return false;
+    }
+
+    free (clusterMap);
+    free (glyphIndices);
+    free (glyphAdvances);
+    free (glyphOffsets);
+
+    glyphCount = actualGlyphsCount;
+    clusterMap = modifiedClusterMap;
+    glyphIndices = modifiedGlyphIndices;
+    glyphAdvances = modifiedGlyphAdvances;
+    glyphOffsets = modifiedGlyphOffsets;
+
+    free(justifiedGlyphAdvances);
+    free(justifiedGlyphOffsets);
+  }
+  else
+  {
+    free(glyphAdvances);
+    free(glyphOffsets);
+
+    glyphAdvances = justifiedGlyphAdvances;
+    glyphOffsets = justifiedGlyphOffsets;
+  }
+
+  free(justificationOpportunities);
+
+#endif
 
   /* 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++)
+  for (unsigned int i = 0; i < glyphCount; i++)
     vis_clusters[i] = -1;
-  for (unsigned int i = 0; i < buffer->len; i++) {
+  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);
+    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++)
+  for (unsigned int i = 1; i < glyphCount; i++)
     if (vis_clusters[i] == -1)
       vis_clusters[i] = vis_clusters[i - 1];
 
 #undef utf16_index
 
-  //if (unlikely (!buffer->ensure (glyphs_len)))
+  if (unlikely (!buffer->ensure (glyphCount)))
-  //  FAIL ("Buffer in error");
+    FAIL ("Buffer in error");
 
 #undef FAIL
 
   /* Set glyph infos */
   buffer->len = 0;
-  for (unsigned int i = 0; i < glyphs_len; i++)
+  for (unsigned int i = 0; i < glyphCount; i++)
   {
     hb_glyph_info_t *info = &buffer->info[buffer->len++];
 
-    info->codepoint = glyphs[i];
+    info->codepoint = glyphIndices[i];
     info->cluster = vis_clusters[i];
 
     /* The rest is crap.  Let's store position info there for now. */
-    info->mask = advances[i];
+    info->mask = glyphAdvances[i];
-    info->var1.u32 = offsets[i].ascenderOffset;
+    info->var1.i32 = glyphOffsets[i].advanceOffset;
-    info->var2.u32 = -offsets[i].advanceOffset;
+    info->var2.i32 = glyphOffsets[i].ascenderOffset;
   }
 
-  free(clusters);
-  free(glyphs);
-  free(textProperties);
-  free(glyphProperties);
-
   /* Set glyph positions */
   buffer->clear_positions ();
-  for (unsigned int i = 0; i < glyphs_len; i++)
+  for (unsigned int i = 0; i < glyphCount; 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_advance = x_mult * (int32_t) info->mask;
-    pos->x_offset = backward ? -info->var1.u32 : info->var1.u32;
+    pos->x_offset =
-    pos->y_offset = info->var2.u32;
+      x_mult * (isRightToLeft ? -info->var1.i32 : info->var1.i32);
+    pos->y_offset = y_mult * info->var2.i32;
   }
 
-  if (backward)
+  if (isRightToLeft)
     hb_buffer_reverse (buffer);
 
+  free (clusterMap);
+  free (glyphIndices);
+  free (textProperties);
+  free (glyphProperties);
+  free (glyphAdvances);
+  free (glyphOffsets);
+
+  if (num_features)
+    free (singleFeatures.features);
+
   /* Wow, done! */
   return true;
 }