diff -r 000000000000 -r 6474c204b198 gfx/thebes/gfxCoreTextShaper.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/thebes/gfxCoreTextShaper.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,638 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "gfxCoreTextShaper.h"
+#include "gfxMacFont.h"
+#include "gfxFontUtils.h"
+#include "mozilla/gfx/2D.h"
+
+#include <algorithm>
+
+using namespace mozilla;
+
+// standard font descriptors that we construct the first time they're needed
+CTFontDescriptorRef gfxCoreTextShaper::sDefaultFeaturesDescriptor = nullptr;
+CTFontDescriptorRef gfxCoreTextShaper::sDisableLigaturesDescriptor = nullptr;
+
+gfxCoreTextShaper::gfxCoreTextShaper(gfxMacFont *aFont)
+    : gfxFontShaper(aFont)
+{
+    // Create our CTFontRef
+    mCTFont = ::CTFontCreateWithGraphicsFont(aFont->GetCGFontRef(),
+                                             aFont->GetAdjustedSize(),
+                                             nullptr,
+                                             GetDefaultFeaturesDescriptor());
+
+    // Set up the default attribute dictionary that we will need each time we create a CFAttributedString
+    mAttributesDict = ::CFDictionaryCreate(kCFAllocatorDefault,
+                                           (const void**) &kCTFontAttributeName,
+                                           (const void**) &mCTFont,
+                                           1, // count of attributes
+                                           &kCFTypeDictionaryKeyCallBacks,
+                                           &kCFTypeDictionaryValueCallBacks);
+}
+
+gfxCoreTextShaper::~gfxCoreTextShaper()
+{
+    if (mAttributesDict) {
+        ::CFRelease(mAttributesDict);
+    }
+    if (mCTFont) {
+        ::CFRelease(mCTFont);
+    }
+}
+
+bool
+gfxCoreTextShaper::ShapeText(gfxContext      *aContext,
+                             const char16_t *aText,
+                             uint32_t         aOffset,
+                             uint32_t         aLength,
+                             int32_t          aScript,
+                             gfxShapedText   *aShapedText)
+{
+    // Create a CFAttributedString with text and style info, so we can use CoreText to lay it out.
+
+    bool isRightToLeft = aShapedText->IsRightToLeft();
+    uint32_t length = aLength;
+
+    // we need to bidi-wrap the text if the run is RTL,
+    // or if it is an LTR run but may contain (overridden) RTL chars
+    bool bidiWrap = isRightToLeft;
+    if (!bidiWrap && !aShapedText->TextIs8Bit()) {
+        uint32_t i;
+        for (i = 0; i < length; ++i) {
+            if (gfxFontUtils::PotentialRTLChar(aText[i])) {
+                bidiWrap = true;
+                break;
+            }
+        }
+    }
+
+    // If there's a possibility of any bidi, we wrap the text with direction overrides
+    // to ensure neutrals or characters that were bidi-overridden in HTML behave properly.
+    const UniChar beginLTR[]    = { 0x202d, 0x20 };
+    const UniChar beginRTL[]    = { 0x202e, 0x20 };
+    const UniChar endBidiWrap[] = { 0x20, 0x2e, 0x202c };
+
+    uint32_t startOffset;
+    CFStringRef stringObj;
+    if (bidiWrap) {
+        startOffset = isRightToLeft ?
+            mozilla::ArrayLength(beginRTL) : mozilla::ArrayLength(beginLTR);
+        CFMutableStringRef mutableString =
+            ::CFStringCreateMutable(kCFAllocatorDefault,
+                                    length + startOffset + mozilla::ArrayLength(endBidiWrap));
+        ::CFStringAppendCharacters(mutableString,
+                                   isRightToLeft ? beginRTL : beginLTR,
+                                   startOffset);
+        ::CFStringAppendCharacters(mutableString, reinterpret_cast<const UniChar*>(aText), length);
+        ::CFStringAppendCharacters(mutableString,
+                                   endBidiWrap, mozilla::ArrayLength(endBidiWrap));
+        stringObj = mutableString;
+    } else {
+        startOffset = 0;
+        stringObj = ::CFStringCreateWithCharactersNoCopy(kCFAllocatorDefault,
+                                                         reinterpret_cast<const UniChar*>(aText),
+                                                         length, kCFAllocatorNull);
+    }
+
+    CFDictionaryRef attrObj;
+    if (aShapedText->DisableLigatures()) {
+        // For letterspacing (or maybe other situations) we need to make a copy of the CTFont
+        // with the ligature feature disabled
+        CTFontRef ctFont =
+            CreateCTFontWithDisabledLigatures(::CTFontGetSize(mCTFont));
+
+        attrObj =
+            ::CFDictionaryCreate(kCFAllocatorDefault,
+                                 (const void**) &kCTFontAttributeName,
+                                 (const void**) &ctFont,
+                                 1, // count of attributes
+                                 &kCFTypeDictionaryKeyCallBacks,
+                                 &kCFTypeDictionaryValueCallBacks);
+        // Having created the dict, we're finished with our ligature-disabled CTFontRef
+        ::CFRelease(ctFont);
+    } else {
+        attrObj = mAttributesDict;
+        ::CFRetain(attrObj);
+    }
+
+    // Now we can create an attributed string
+    CFAttributedStringRef attrStringObj =
+        ::CFAttributedStringCreate(kCFAllocatorDefault, stringObj, attrObj);
+    ::CFRelease(stringObj);
+    ::CFRelease(attrObj);
+
+    // Create the CoreText line from our string, then we're done with it
+    CTLineRef line = ::CTLineCreateWithAttributedString(attrStringObj);
+    ::CFRelease(attrStringObj);
+
+    // and finally retrieve the glyph data and store into the gfxTextRun
+    CFArrayRef glyphRuns = ::CTLineGetGlyphRuns(line);
+    uint32_t numRuns = ::CFArrayGetCount(glyphRuns);
+
+    // Iterate through the glyph runs.
+    // Note that this includes the bidi wrapper, so we have to be careful
+    // not to include the extra glyphs from there
+    bool success = true;
+    for (uint32_t runIndex = 0; runIndex < numRuns; runIndex++) {
+        CTRunRef aCTRun =
+            (CTRunRef)::CFArrayGetValueAtIndex(glyphRuns, runIndex);
+        if (SetGlyphsFromRun(aShapedText, aOffset, aLength, aCTRun, startOffset) != NS_OK) {
+            success = false;
+            break;
+        }
+    }
+
+    ::CFRelease(line);
+
+    return success;
+}
+
+#define SMALL_GLYPH_RUN 128 // preallocated size of our auto arrays for per-glyph data;
+                            // some testing indicates that 90%+ of glyph runs will fit
+                            // without requiring a separate allocation
+
+nsresult
+gfxCoreTextShaper::SetGlyphsFromRun(gfxShapedText *aShapedText,
+                                    uint32_t       aOffset,
+                                    uint32_t       aLength,
+                                    CTRunRef       aCTRun,
+                                    int32_t        aStringOffset)
+{
+    // The word has been bidi-wrapped; aStringOffset is the number
+    // of chars at the beginning of the CTLine that we should skip.
+    // aCTRun is a glyph run from the CoreText layout process.
+
+    int32_t direction = aShapedText->IsRightToLeft() ? -1 : 1;
+
+    int32_t numGlyphs = ::CTRunGetGlyphCount(aCTRun);
+    if (numGlyphs == 0) {
+        return NS_OK;
+    }
+
+    int32_t wordLength = aLength;
+
+    // character offsets get really confusing here, as we have to keep track of
+    // (a) the text in the actual textRun we're constructing
+    // (c) the string that was handed to CoreText, which contains the text of the font run
+    //     plus directional-override padding
+    // (d) the CTRun currently being processed, which may be a sub-run of the CoreText line
+    //     (but may extend beyond the actual font run into the bidi wrapping text).
+    //     aStringOffset tells us how many initial characters of the line to ignore.
+
+    // get the source string range within the CTLine's text
+    CFRange stringRange = ::CTRunGetStringRange(aCTRun);
+    // skip the run if it is entirely outside the actual range of the font run
+    if (stringRange.location - aStringOffset + stringRange.length <= 0 ||
+        stringRange.location - aStringOffset >= wordLength) {
+        return NS_OK;
+    }
+
+    // retrieve the laid-out glyph data from the CTRun
+    nsAutoArrayPtr<CGGlyph> glyphsArray;
+    nsAutoArrayPtr<CGPoint> positionsArray;
+    nsAutoArrayPtr<CFIndex> glyphToCharArray;
+    const CGGlyph* glyphs = nullptr;
+    const CGPoint* positions = nullptr;
+    const CFIndex* glyphToChar = nullptr;
+
+    // Testing indicates that CTRunGetGlyphsPtr (almost?) always succeeds,
+    // and so allocating a new array and copying data with CTRunGetGlyphs
+    // will be extremely rare.
+    // If this were not the case, we could use an nsAutoTArray<> to
+    // try and avoid the heap allocation for small runs.
+    // It's possible that some future change to CoreText will mean that
+    // CTRunGetGlyphsPtr fails more often; if this happens, nsAutoTArray<>
+    // may become an attractive option.
+    glyphs = ::CTRunGetGlyphsPtr(aCTRun);
+    if (!glyphs) {
+        glyphsArray = new (std::nothrow) CGGlyph[numGlyphs];
+        if (!glyphsArray) {
+            return NS_ERROR_OUT_OF_MEMORY;
+        }
+        ::CTRunGetGlyphs(aCTRun, ::CFRangeMake(0, 0), glyphsArray.get());
+        glyphs = glyphsArray.get();
+    }
+
+    positions = ::CTRunGetPositionsPtr(aCTRun);
+    if (!positions) {
+        positionsArray = new (std::nothrow) CGPoint[numGlyphs];
+        if (!positionsArray) {
+            return NS_ERROR_OUT_OF_MEMORY;
+        }
+        ::CTRunGetPositions(aCTRun, ::CFRangeMake(0, 0), positionsArray.get());
+        positions = positionsArray.get();
+    }
+
+    // Remember that the glyphToChar indices relate to the CoreText line,
+    // not to the beginning of the textRun, the font run,
+    // or the stringRange of the glyph run
+    glyphToChar = ::CTRunGetStringIndicesPtr(aCTRun);
+    if (!glyphToChar) {
+        glyphToCharArray = new (std::nothrow) CFIndex[numGlyphs];
+        if (!glyphToCharArray) {
+            return NS_ERROR_OUT_OF_MEMORY;
+        }
+        ::CTRunGetStringIndices(aCTRun, ::CFRangeMake(0, 0), glyphToCharArray.get());
+        glyphToChar = glyphToCharArray.get();
+    }
+
+    double runWidth = ::CTRunGetTypographicBounds(aCTRun, ::CFRangeMake(0, 0),
+                                                  nullptr, nullptr, nullptr);
+
+    nsAutoTArray<gfxShapedText::DetailedGlyph,1> detailedGlyphs;
+    gfxShapedText::CompressedGlyph g;
+    gfxShapedText::CompressedGlyph *charGlyphs =
+        aShapedText->GetCharacterGlyphs() + aOffset;
+
+    // CoreText gives us the glyphindex-to-charindex mapping, which relates each glyph
+    // to a source text character; we also need the charindex-to-glyphindex mapping to
+    // find the glyph for a given char. Note that some chars may not map to any glyph
+    // (ligature continuations), and some may map to several glyphs (eg Indic split vowels).
+    // We set the glyph index to NO_GLYPH for chars that have no associated glyph, and we
+    // record the last glyph index for cases where the char maps to several glyphs,
+    // so that our clumping will include all the glyph fragments for the character.
+
+    // The charToGlyph array is indexed by char position within the stringRange of the glyph run.
+
+    static const int32_t NO_GLYPH = -1;
+    AutoFallibleTArray<int32_t,SMALL_GLYPH_RUN> charToGlyphArray;
+    if (!charToGlyphArray.SetLength(stringRange.length)) {
+        return NS_ERROR_OUT_OF_MEMORY;
+    }
+    int32_t *charToGlyph = charToGlyphArray.Elements();
+    for (int32_t offset = 0; offset < stringRange.length; ++offset) {
+        charToGlyph[offset] = NO_GLYPH;
+    }
+    for (int32_t i = 0; i < numGlyphs; ++i) {
+        int32_t loc = glyphToChar[i] - stringRange.location;
+        if (loc >= 0 && loc < stringRange.length) {
+            charToGlyph[loc] = i;
+        }
+    }
+
+    // Find character and glyph clumps that correspond, allowing for ligatures,
+    // indic reordering, split glyphs, etc.
+    //
+    // The idea is that we'll find a character sequence starting at the first char of stringRange,
+    // and extend it until it includes the character associated with the first glyph;
+    // we also extend it as long as there are "holes" in the range of glyphs. So we
+    // will eventually have a contiguous sequence of characters, starting at the beginning
+    // of the range, that map to a contiguous sequence of glyphs, starting at the beginning
+    // of the glyph array. That's a clump; then we update the starting positions and repeat.
+    //
+    // NB: In the case of RTL layouts, we iterate over the stringRange in reverse.
+    //
+
+    // This may find characters that fall outside the range 0:wordLength,
+    // so we won't necessarily use everything we find here.
+
+    bool isRightToLeft = aShapedText->IsRightToLeft();
+    int32_t glyphStart = 0; // looking for a clump that starts at this glyph index
+    int32_t charStart = isRightToLeft ?
+        stringRange.length - 1 : 0; // and this char index (in the stringRange of the glyph run)
+
+    while (glyphStart < numGlyphs) { // keep finding groups until all glyphs are accounted for
+        bool inOrder = true;
+        int32_t charEnd = glyphToChar[glyphStart] - stringRange.location;
+        NS_WARN_IF_FALSE(charEnd >= 0 && charEnd < stringRange.length,
+                         "glyph-to-char mapping points outside string range");
+        // clamp charEnd to the valid range of the string
+        charEnd = std::max(charEnd, 0);
+        charEnd = std::min(charEnd, int32_t(stringRange.length));
+
+        int32_t glyphEnd = glyphStart;
+        int32_t charLimit = isRightToLeft ? -1 : stringRange.length;
+        do {
+            // This is normally executed once for each iteration of the outer loop,
+            // but in unusual cases where the character/glyph association is complex,
+            // the initial character range might correspond to a non-contiguous
+            // glyph range with "holes" in it. If so, we will repeat this loop to
+            // extend the character range until we have a contiguous glyph sequence.
+            NS_ASSERTION((direction > 0 && charEnd < charLimit) ||
+                         (direction < 0 && charEnd > charLimit),
+                         "no characters left in range?");
+            charEnd += direction;
+            while (charEnd != charLimit && charToGlyph[charEnd] == NO_GLYPH) {
+                charEnd += direction;
+            }
+
+            // find the maximum glyph index covered by the clump so far
+            if (isRightToLeft) {
+                for (int32_t i = charStart; i > charEnd; --i) {
+                    if (charToGlyph[i] != NO_GLYPH) {
+                        // update extent of glyph range
+                        glyphEnd = std::max(glyphEnd, charToGlyph[i] + 1);
+                    }
+                }
+            } else {
+                for (int32_t i = charStart; i < charEnd; ++i) {
+                    if (charToGlyph[i] != NO_GLYPH) {
+                        // update extent of glyph range
+                        glyphEnd = std::max(glyphEnd, charToGlyph[i] + 1);
+                    }
+                }
+            }
+
+            if (glyphEnd == glyphStart + 1) {
+                // for the common case of a single-glyph clump, we can skip the following checks
+                break;
+            }
+
+            if (glyphEnd == glyphStart) {
+                // no glyphs, try to extend the clump
+                continue;
+            }
+
+            // check whether all glyphs in the range are associated with the characters
+            // in our clump; if not, we have a discontinuous range, and should extend it
+            // unless we've reached the end of the text
+            bool allGlyphsAreWithinCluster = true;
+            int32_t prevGlyphCharIndex = charStart;
+            for (int32_t i = glyphStart; i < glyphEnd; ++i) {
+                int32_t glyphCharIndex = glyphToChar[i] - stringRange.location;
+                if (isRightToLeft) {
+                    if (glyphCharIndex > charStart || glyphCharIndex <= charEnd) {
+                        allGlyphsAreWithinCluster = false;
+                        break;
+                    }
+                    if (glyphCharIndex > prevGlyphCharIndex) {
+                        inOrder = false;
+                    }
+                    prevGlyphCharIndex = glyphCharIndex;
+                } else {
+                    if (glyphCharIndex < charStart || glyphCharIndex >= charEnd) {
+                        allGlyphsAreWithinCluster = false;
+                        break;
+                    }
+                    if (glyphCharIndex < prevGlyphCharIndex) {
+                        inOrder = false;
+                    }
+                    prevGlyphCharIndex = glyphCharIndex;
+                }
+            }
+            if (allGlyphsAreWithinCluster) {
+                break;
+            }
+        } while (charEnd != charLimit);
+
+        NS_WARN_IF_FALSE(glyphStart < glyphEnd,
+                         "character/glyph clump contains no glyphs!");
+        if (glyphStart == glyphEnd) {
+            ++glyphStart; // make progress - avoid potential infinite loop
+            charStart = charEnd;
+            continue;
+        }
+
+        NS_WARN_IF_FALSE(charStart != charEnd,
+                         "character/glyph clump contains no characters!");
+        if (charStart == charEnd) {
+            glyphStart = glyphEnd; // this is bad - we'll discard the glyph(s),
+                                   // as there's nowhere to attach them
+            continue;
+        }
+
+        // Now charStart..charEnd is a ligature clump, corresponding to glyphStart..glyphEnd;
+        // Set baseCharIndex to the char we'll actually attach the glyphs to (1st of ligature),
+        // and endCharIndex to the limit (position beyond the last char),
+        // adjusting for the offset of the stringRange relative to the textRun.
+        int32_t baseCharIndex, endCharIndex;
+        if (isRightToLeft) {
+            while (charEnd >= 0 && charToGlyph[charEnd] == NO_GLYPH) {
+                charEnd--;
+            }
+            baseCharIndex = charEnd + stringRange.location - aStringOffset + 1;
+            endCharIndex = charStart + stringRange.location - aStringOffset + 1;
+        } else {
+            while (charEnd < stringRange.length && charToGlyph[charEnd] == NO_GLYPH) {
+                charEnd++;
+            }
+            baseCharIndex = charStart + stringRange.location - aStringOffset;
+            endCharIndex = charEnd + stringRange.location - aStringOffset;
+        }
+
+        // Then we check if the clump falls outside our actual string range; if so, just go to the next.
+        if (endCharIndex <= 0 || baseCharIndex >= wordLength) {
+            glyphStart = glyphEnd;
+            charStart = charEnd;
+            continue;
+        }
+        // Ensure we won't try to go beyond the valid length of the word's text
+        baseCharIndex = std::max(baseCharIndex, 0);
+        endCharIndex = std::min(endCharIndex, wordLength);
+
+        // Now we're ready to set the glyph info in the textRun; measure the glyph width
+        // of the first (perhaps only) glyph, to see if it is "Simple"
+        int32_t appUnitsPerDevUnit = aShapedText->GetAppUnitsPerDevUnit();
+        double toNextGlyph;
+        if (glyphStart < numGlyphs-1) {
+            toNextGlyph = positions[glyphStart+1].x - positions[glyphStart].x;
+        } else {
+            toNextGlyph = positions[0].x + runWidth - positions[glyphStart].x;
+        }
+        int32_t advance = int32_t(toNextGlyph * appUnitsPerDevUnit);
+
+        // Check if it's a simple one-to-one mapping
+        int32_t glyphsInClump = glyphEnd - glyphStart;
+        if (glyphsInClump == 1 &&
+            gfxTextRun::CompressedGlyph::IsSimpleGlyphID(glyphs[glyphStart]) &&
+            gfxTextRun::CompressedGlyph::IsSimpleAdvance(advance) &&
+            charGlyphs[baseCharIndex].IsClusterStart() &&
+            positions[glyphStart].y == 0.0)
+        {
+            charGlyphs[baseCharIndex].SetSimpleGlyph(advance,
+                                                     glyphs[glyphStart]);
+        } else {
+            // collect all glyphs in a list to be assigned to the first char;
+            // there must be at least one in the clump, and we already measured its advance,
+            // hence the placement of the loop-exit test and the measurement of the next glyph
+            while (1) {
+                gfxTextRun::DetailedGlyph *details = detailedGlyphs.AppendElement();
+                details->mGlyphID = glyphs[glyphStart];
+                details->mXOffset = 0;
+                details->mYOffset = -positions[glyphStart].y * appUnitsPerDevUnit;
+                details->mAdvance = advance;
+                if (++glyphStart >= glyphEnd) {
+                   break;
+                }
+                if (glyphStart < numGlyphs-1) {
+                    toNextGlyph = positions[glyphStart+1].x - positions[glyphStart].x;
+                } else {
+                    toNextGlyph = positions[0].x + runWidth - positions[glyphStart].x;
+                }
+                advance = int32_t(toNextGlyph * appUnitsPerDevUnit);
+            }
+
+            gfxTextRun::CompressedGlyph g;
+            g.SetComplex(charGlyphs[baseCharIndex].IsClusterStart(),
+                         true, detailedGlyphs.Length());
+            aShapedText->SetGlyphs(aOffset + baseCharIndex, g, detailedGlyphs.Elements());
+
+            detailedGlyphs.Clear();
+        }
+
+        // the rest of the chars in the group are ligature continuations, no associated glyphs
+        while (++baseCharIndex != endCharIndex && baseCharIndex < wordLength) {
+            gfxShapedText::CompressedGlyph &g = charGlyphs[baseCharIndex];
+            NS_ASSERTION(!g.IsSimpleGlyph(), "overwriting a simple glyph");
+            g.SetComplex(inOrder && g.IsClusterStart(), false, 0);
+        }
+
+        glyphStart = glyphEnd;
+        charStart = charEnd;
+    }
+
+    return NS_OK;
+}
+
+#undef SMALL_GLYPH_RUN
+
+// Construct the font attribute descriptor that we'll apply by default when creating a CTFontRef.
+// This will turn off line-edge swashes by default, because we don't know the actual line breaks
+// when doing glyph shaping.
+void
+gfxCoreTextShaper::CreateDefaultFeaturesDescriptor()
+{
+    if (sDefaultFeaturesDescriptor != nullptr) {
+        return;
+    }
+
+    SInt16 val = kSmartSwashType;
+    CFNumberRef swashesType =
+        ::CFNumberCreate(kCFAllocatorDefault,
+                         kCFNumberSInt16Type,
+                         &val);
+    val = kLineInitialSwashesOffSelector;
+    CFNumberRef lineInitialsOffSelector =
+        ::CFNumberCreate(kCFAllocatorDefault,
+                         kCFNumberSInt16Type,
+                         &val);
+
+    CFTypeRef keys[]   = { kCTFontFeatureTypeIdentifierKey,
+                           kCTFontFeatureSelectorIdentifierKey };
+    CFTypeRef values[] = { swashesType,
+                           lineInitialsOffSelector };
+    CFDictionaryRef featureSettings[2];
+    featureSettings[0] =
+        ::CFDictionaryCreate(kCFAllocatorDefault,
+                             (const void **) keys,
+                             (const void **) values,
+                             ArrayLength(keys),
+                             &kCFTypeDictionaryKeyCallBacks,
+                             &kCFTypeDictionaryValueCallBacks);
+    ::CFRelease(lineInitialsOffSelector);
+
+    val = kLineFinalSwashesOffSelector;
+    CFNumberRef lineFinalsOffSelector =
+        ::CFNumberCreate(kCFAllocatorDefault,
+                         kCFNumberSInt16Type,
+                         &val);
+    values[1] = lineFinalsOffSelector;
+    featureSettings[1] =
+        ::CFDictionaryCreate(kCFAllocatorDefault,
+                             (const void **) keys,
+                             (const void **) values,
+                             ArrayLength(keys),
+                             &kCFTypeDictionaryKeyCallBacks,
+                             &kCFTypeDictionaryValueCallBacks);
+    ::CFRelease(lineFinalsOffSelector);
+    ::CFRelease(swashesType);
+
+    CFArrayRef featuresArray =
+        ::CFArrayCreate(kCFAllocatorDefault,
+                        (const void **) featureSettings,
+                        ArrayLength(featureSettings),
+                        &kCFTypeArrayCallBacks);
+    ::CFRelease(featureSettings[0]);
+    ::CFRelease(featureSettings[1]);
+
+    const CFTypeRef attrKeys[]   = { kCTFontFeatureSettingsAttribute };
+    const CFTypeRef attrValues[] = { featuresArray };
+    CFDictionaryRef attributesDict =
+        ::CFDictionaryCreate(kCFAllocatorDefault,
+                             (const void **) attrKeys,
+                             (const void **) attrValues,
+                             ArrayLength(attrKeys),
+                             &kCFTypeDictionaryKeyCallBacks,
+                             &kCFTypeDictionaryValueCallBacks);
+    ::CFRelease(featuresArray);
+
+    sDefaultFeaturesDescriptor =
+        ::CTFontDescriptorCreateWithAttributes(attributesDict);
+    ::CFRelease(attributesDict);
+}
+
+// Create a CTFontRef, with the Common Ligatures feature disabled
+CTFontRef
+gfxCoreTextShaper::CreateCTFontWithDisabledLigatures(CGFloat aSize)
+{
+    if (sDisableLigaturesDescriptor == nullptr) {
+        // initialize cached descriptor to turn off the Common Ligatures feature
+        SInt16 val = kLigaturesType;
+        CFNumberRef ligaturesType =
+            ::CFNumberCreate(kCFAllocatorDefault,
+                             kCFNumberSInt16Type,
+                             &val);
+        val = kCommonLigaturesOffSelector;
+        CFNumberRef commonLigaturesOffSelector =
+            ::CFNumberCreate(kCFAllocatorDefault,
+                             kCFNumberSInt16Type,
+                             &val);
+
+        const CFTypeRef keys[]   = { kCTFontFeatureTypeIdentifierKey,
+                                     kCTFontFeatureSelectorIdentifierKey };
+        const CFTypeRef values[] = { ligaturesType,
+                                     commonLigaturesOffSelector };
+        CFDictionaryRef featureSettingDict =
+            ::CFDictionaryCreate(kCFAllocatorDefault,
+                                 (const void **) keys,
+                                 (const void **) values,
+                                 ArrayLength(keys),
+                                 &kCFTypeDictionaryKeyCallBacks,
+                                 &kCFTypeDictionaryValueCallBacks);
+        ::CFRelease(ligaturesType);
+        ::CFRelease(commonLigaturesOffSelector);
+
+        CFArrayRef featuresArray =
+            ::CFArrayCreate(kCFAllocatorDefault,
+                            (const void **) &featureSettingDict,
+                            1,
+                            &kCFTypeArrayCallBacks);
+        ::CFRelease(featureSettingDict);
+
+        CFDictionaryRef attributesDict =
+            ::CFDictionaryCreate(kCFAllocatorDefault,
+                                 (const void **) &kCTFontFeatureSettingsAttribute,
+                                 (const void **) &featuresArray,
+                                 1, // count of keys & values
+                                 &kCFTypeDictionaryKeyCallBacks,
+                                 &kCFTypeDictionaryValueCallBacks);
+        ::CFRelease(featuresArray);
+
+        sDisableLigaturesDescriptor =
+            ::CTFontDescriptorCreateCopyWithAttributes(GetDefaultFeaturesDescriptor(),
+                                                       attributesDict);
+        ::CFRelease(attributesDict);
+    }
+
+    gfxMacFont *f = static_cast<gfxMacFont*>(mFont);
+    return ::CTFontCreateWithGraphicsFont(f->GetCGFontRef(), aSize, nullptr,
+                                          sDisableLigaturesDescriptor);
+}
+
+void
+gfxCoreTextShaper::Shutdown() // [static]
+{
+    if (sDisableLigaturesDescriptor != nullptr) {
+        ::CFRelease(sDisableLigaturesDescriptor);
+        sDisableLigaturesDescriptor = nullptr;
+    }        
+    if (sDefaultFeaturesDescriptor != nullptr) {
+        ::CFRelease(sDefaultFeaturesDescriptor);
+        sDefaultFeaturesDescriptor = nullptr;
+    }
+}