gecko-dev/gfx/2d/ScaledFontDWrite.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "ScaledFontDWrite.h"
#include "UnscaledFontDWrite.h"
#include "PathD2D.h"
#include "gfxFont.h"
#include "Logging.h"
#include "mozilla/FontPropertyTypes.h"
#include "mozilla/webrender/WebRenderTypes.h"
#include "HelpersD2D.h"

#include "dwrite_3.h"

// Currently, we build with WINVER=0x601 (Win7), which means newer
// declarations in dwrite_3.h will not be visible. Also, we don't
// yet have the Fall Creators Update SDK available on build machines,
// so even with updated WINVER, some of the interfaces we need would
// not be present.
// To work around this, until the build environment is updated,
// we #include an extra header that contains copies of the relevant
// classes/interfaces we need.
#if !defined(__MINGW32__) && WINVER < 0x0A00
#  include "dw-extra.h"
#endif

using namespace std;

#ifdef USE_SKIA
#  include "PathSkia.h"
#  include "skia/include/core/SkPaint.h"
#  include "skia/include/core/SkPath.h"
#  include "skia/include/ports/SkTypeface_win.h"
#endif

#include <vector>

#ifdef USE_CAIRO_SCALED_FONT
#  include "cairo-win32.h"
#endif

#include "HelpersWinFonts.h"

namespace mozilla {
namespace gfx {

#define GASP_TAG 0x70736167
#define GASP_DOGRAY 0x2

static inline unsigned short readShort(const char* aBuf) {
  return (*aBuf << 8) | *(aBuf + 1);
}

static bool DoGrayscale(IDWriteFontFace* aDWFace, Float ppem) {
  void* tableContext;
  char* tableData;
  UINT32 tableSize;
  BOOL exists;
  aDWFace->TryGetFontTable(GASP_TAG, (const void**)&tableData, &tableSize,
                           &tableContext, &exists);

  if (exists) {
    if (tableSize < 4) {
      aDWFace->ReleaseFontTable(tableContext);
      return true;
    }
    struct gaspRange {
      unsigned short maxPPEM;   // Stored big-endian
      unsigned short behavior;  // Stored big-endian
    };
    unsigned short numRanges = readShort(tableData + 2);
    if (tableSize < (UINT)4 + numRanges * 4) {
      aDWFace->ReleaseFontTable(tableContext);
      return true;
    }
    gaspRange* ranges = (gaspRange*)(tableData + 4);
    for (int i = 0; i < numRanges; i++) {
      if (readShort((char*)&ranges[i].maxPPEM) > ppem) {
        if (!(readShort((char*)&ranges[i].behavior) & GASP_DOGRAY)) {
          aDWFace->ReleaseFontTable(tableContext);
          return false;
        }
        break;
      }
    }
    aDWFace->ReleaseFontTable(tableContext);
  }
  return true;
}

static inline DWRITE_FONT_STRETCH DWriteFontStretchFromStretch(
    FontStretch aStretch) {
  if (aStretch == FontStretch::UltraCondensed()) {
    return DWRITE_FONT_STRETCH_ULTRA_CONDENSED;
  }
  if (aStretch == FontStretch::ExtraCondensed()) {
    return DWRITE_FONT_STRETCH_EXTRA_CONDENSED;
  }
  if (aStretch == FontStretch::Condensed()) {
    return DWRITE_FONT_STRETCH_CONDENSED;
  }
  if (aStretch == FontStretch::SemiCondensed()) {
    return DWRITE_FONT_STRETCH_SEMI_CONDENSED;
  }
  if (aStretch == FontStretch::Normal()) {
    return DWRITE_FONT_STRETCH_NORMAL;
  }
  if (aStretch == FontStretch::SemiExpanded()) {
    return DWRITE_FONT_STRETCH_SEMI_EXPANDED;
  }
  if (aStretch == FontStretch::Expanded()) {
    return DWRITE_FONT_STRETCH_EXPANDED;
  }
  if (aStretch == FontStretch::ExtraExpanded()) {
    return DWRITE_FONT_STRETCH_EXTRA_EXPANDED;
  }
  if (aStretch == FontStretch::UltraExpanded()) {
    return DWRITE_FONT_STRETCH_ULTRA_EXPANDED;
  }
  return DWRITE_FONT_STRETCH_UNDEFINED;
}

ScaledFontDWrite::ScaledFontDWrite(IDWriteFontFace* aFontFace,
                                   const RefPtr<UnscaledFont>& aUnscaledFont,
                                   Float aSize, bool aUseEmbeddedBitmap,
                                   bool aForceGDIMode,
                                   IDWriteRenderingParams* aParams,
                                   Float aGamma, Float aContrast,
                                   const gfxFontStyle* aStyle)
    : ScaledFontBase(aUnscaledFont, aSize),
      mFontFace(aFontFace),
      mUseEmbeddedBitmap(aUseEmbeddedBitmap),
      mForceGDIMode(aForceGDIMode),
      mParams(aParams),
      mGamma(aGamma),
      mContrast(aContrast) {
  if (aStyle) {
    mStyle = SkFontStyle(aStyle->weight.ToIntRounded(),
                         DWriteFontStretchFromStretch(aStyle->stretch),
                         // FIXME(jwatt): also use kOblique_Slant
                         aStyle->style == FontSlantStyle::Normal()
                             ? SkFontStyle::kUpright_Slant
                             : SkFontStyle::kItalic_Slant);
  }
}

already_AddRefed<Path> ScaledFontDWrite::GetPathForGlyphs(
    const GlyphBuffer& aBuffer, const DrawTarget* aTarget) {

  RefPtr<PathBuilder> pathBuilder = aTarget->CreatePathBuilder();

  if (pathBuilder->GetBackendType() != BackendType::DIRECT2D &&
      pathBuilder->GetBackendType() != BackendType::DIRECT2D1_1) {
    return ScaledFontBase::GetPathForGlyphs(aBuffer, aTarget);
  }

  PathBuilderD2D* pathBuilderD2D =
      static_cast<PathBuilderD2D*>(pathBuilder.get());

  CopyGlyphsToSink(aBuffer, pathBuilderD2D->GetSink());

  return pathBuilder->Finish();
}

#ifdef USE_SKIA
SkTypeface* ScaledFontDWrite::CreateSkTypeface() {
  RefPtr<IDWriteFactory> factory = Factory::GetDWriteFactory();
  if (!factory) {
    return nullptr;
  }

  Float gamma = mGamma;
  // Skia doesn't support a gamma value outside of 0-4, so default to 2.2
  if (gamma < 0.0f || gamma > 4.0f) {
    gamma = 2.2f;
  }

  Float contrast = mContrast;
  // Skia doesn't support a contrast value outside of 0-1, so default to 1.0
  if (contrast < 0.0f || contrast > 1.0f) {
    contrast = 1.0f;
  }

  return SkCreateTypefaceFromDWriteFont(factory, mFontFace, mStyle,
                                        mForceGDIMode, gamma, contrast);
}
#endif

void ScaledFontDWrite::CopyGlyphsToBuilder(const GlyphBuffer& aBuffer,
                                           PathBuilder* aBuilder,
                                           const Matrix* aTransformHint) {
  BackendType backendType = aBuilder->GetBackendType();
  if (backendType == BackendType::CAPTURE) {
    StreamingGeometrySink sink(aBuilder);
    CopyGlyphsToSink(aBuffer, &sink);
    return;
  }

  if (backendType != BackendType::DIRECT2D &&
      backendType != BackendType::DIRECT2D1_1) {
    ScaledFontBase::CopyGlyphsToBuilder(aBuffer, aBuilder, aTransformHint);
    return;
  }

  PathBuilderD2D* pathBuilderD2D = static_cast<PathBuilderD2D*>(aBuilder);

  if (pathBuilderD2D->IsFigureActive()) {
    gfxCriticalNote
        << "Attempting to copy glyphs to PathBuilderD2D with active figure.";
  }

  CopyGlyphsToSink(aBuffer, pathBuilderD2D->GetSink());
}

void ScaledFontDWrite::GetGlyphDesignMetrics(const uint16_t* aGlyphs,
                                             uint32_t aNumGlyphs,
                                             GlyphMetrics* aGlyphMetrics) {
  DWRITE_FONT_METRICS fontMetrics;
  mFontFace->GetMetrics(&fontMetrics);

  vector<DWRITE_GLYPH_METRICS> metrics(aNumGlyphs);
  mFontFace->GetDesignGlyphMetrics(aGlyphs, aNumGlyphs, &metrics.front());

  Float scaleFactor = mSize / fontMetrics.designUnitsPerEm;

  for (uint32_t i = 0; i < aNumGlyphs; i++) {
    aGlyphMetrics[i].mXBearing = metrics[i].leftSideBearing * scaleFactor;
    aGlyphMetrics[i].mXAdvance = metrics[i].advanceWidth * scaleFactor;
    aGlyphMetrics[i].mYBearing =
        (metrics[i].topSideBearing - metrics[i].verticalOriginY) * scaleFactor;
    aGlyphMetrics[i].mYAdvance = metrics[i].advanceHeight * scaleFactor;
    aGlyphMetrics[i].mWidth =
        (metrics[i].advanceWidth - metrics[i].leftSideBearing -
         metrics[i].rightSideBearing) *
        scaleFactor;
    aGlyphMetrics[i].mHeight =
        (metrics[i].advanceHeight - metrics[i].topSideBearing -
         metrics[i].bottomSideBearing) *
        scaleFactor;
  }
}

void ScaledFontDWrite::CopyGlyphsToSink(const GlyphBuffer& aBuffer,
                                        ID2D1SimplifiedGeometrySink* aSink) {
  std::vector<UINT16> indices;
  std::vector<FLOAT> advances;
  std::vector<DWRITE_GLYPH_OFFSET> offsets;
  indices.resize(aBuffer.mNumGlyphs);
  advances.resize(aBuffer.mNumGlyphs);
  offsets.resize(aBuffer.mNumGlyphs);

  memset(&advances.front(), 0, sizeof(FLOAT) * aBuffer.mNumGlyphs);
  for (unsigned int i = 0; i < aBuffer.mNumGlyphs; i++) {
    indices[i] = aBuffer.mGlyphs[i].mIndex;
    offsets[i].advanceOffset = aBuffer.mGlyphs[i].mPosition.x;
    offsets[i].ascenderOffset = -aBuffer.mGlyphs[i].mPosition.y;
  }

  HRESULT hr = mFontFace->GetGlyphRunOutline(
      mSize, &indices.front(), &advances.front(), &offsets.front(),
      aBuffer.mNumGlyphs, FALSE, FALSE, aSink);
  if (FAILED(hr)) {
    gfxCriticalNote << "Failed to copy glyphs to geometry sink. Code: "
                    << hexa(hr);
  }
}

bool UnscaledFontDWrite::GetFontFileData(FontFileDataOutput aDataCallback,
                                         void* aBaton) {
  UINT32 fileCount = 0;
  HRESULT hr = mFontFace->GetFiles(&fileCount, nullptr);

  if (FAILED(hr) || fileCount > 1) {
    MOZ_ASSERT(false);
    return false;
  }

  if (!aDataCallback) {
    return true;
  }

  RefPtr<IDWriteFontFile> file;
  hr = mFontFace->GetFiles(&fileCount, getter_AddRefs(file));
  if (FAILED(hr)) {
    return false;
  }

  const void* referenceKey;
  UINT32 refKeySize;
  // XXX - This can currently crash for webfonts, as when we get the reference
  // key out of the file, that can be an invalid reference key for the loader
  // we use it with. The fix to this is not obvious but it will probably
  // have to happen inside thebes.
  hr = file->GetReferenceKey(&referenceKey, &refKeySize);
  if (FAILED(hr)) {
    return false;
  }

  RefPtr<IDWriteFontFileLoader> loader;
  hr = file->GetLoader(getter_AddRefs(loader));
  if (FAILED(hr)) {
    return false;
  }

  RefPtr<IDWriteFontFileStream> stream;
  hr = loader->CreateStreamFromKey(referenceKey, refKeySize, getter_AddRefs(stream));
  if (FAILED(hr)) {
    return false;
  }

  UINT64 fileSize64;
  hr = stream->GetFileSize(&fileSize64);
  if (FAILED(hr) || fileSize64 > UINT32_MAX) {
    MOZ_ASSERT(false);
    return false;
  }

  uint32_t fileSize = static_cast<uint32_t>(fileSize64);
  const void* fragmentStart;
  void* context;
  hr = stream->ReadFileFragment(&fragmentStart, 0, fileSize, &context);
  if (FAILED(hr)) {
    return false;
  }

  aDataCallback((uint8_t*)fragmentStart, fileSize, mFontFace->GetIndex(),
                aBaton);

  stream->ReleaseFileFragment(context);

  return true;
}

static bool GetFontFileName(RefPtr<IDWriteFontFace> aFontFace,
                            std::vector<WCHAR>& aFileName) {
  UINT32 numFiles;
  HRESULT hr = aFontFace->GetFiles(&numFiles, nullptr);
  if (FAILED(hr)) {
    gfxDebug() << "Failed getting file count for WR font";
    return false;
  } else if (numFiles != 1) {
    gfxDebug() << "Invalid file count " << numFiles << " for WR font";
    return false;
  }

  RefPtr<IDWriteFontFile> file;
  hr = aFontFace->GetFiles(&numFiles, getter_AddRefs(file));
  if (FAILED(hr)) {
    gfxDebug() << "Failed getting file for WR font";
    return false;
  }

  const void* key;
  UINT32 keySize;
  hr = file->GetReferenceKey(&key, &keySize);
  if (FAILED(hr)) {
    gfxDebug() << "Failed getting file ref key for WR font";
    return false;
  }
  RefPtr<IDWriteFontFileLoader> loader;
  hr = file->GetLoader(getter_AddRefs(loader));
  if (FAILED(hr)) {
    gfxDebug() << "Failed getting file loader for WR font";
    return false;
  }
  RefPtr<IDWriteLocalFontFileLoader> localLoader;
  loader->QueryInterface(__uuidof(IDWriteLocalFontFileLoader),
                         (void**)getter_AddRefs(localLoader));
  if (!localLoader) {
    gfxDebug() << "Failed querying loader interface for WR font";
    return false;
  }
  UINT32 pathLen;
  hr = localLoader->GetFilePathLengthFromKey(key, keySize, &pathLen);
  if (FAILED(hr)) {
    gfxDebug() << "Failed getting path length for WR font";
    return false;
  }
  aFileName.resize(pathLen + 1);
  hr = localLoader->GetFilePathFromKey(key, keySize, aFileName.data(),
                                       pathLen + 1);
  if (FAILED(hr) || aFileName.back() != 0) {
    gfxDebug() << "Failed getting path for WR font";
    return false;
  }
  DWORD attribs = GetFileAttributesW(aFileName.data());
  if (attribs == INVALID_FILE_ATTRIBUTES) {
    gfxDebug() << "Invalid file \"" << aFileName.data() << "\" for WR font";
    return false;
  }
  aFileName.pop_back();
  return true;
}

bool UnscaledFontDWrite::GetWRFontDescriptor(WRFontDescriptorOutput aCb,
                                             void* aBaton) {
  if (!mFont) {
    return false;
  }

  std::vector<WCHAR> fileName;
  if (!GetFontFileName(mFontFace, fileName)) {
    return false;
  }
  uint32_t index = mFontFace->GetIndex();

  aCb(reinterpret_cast<const uint8_t*>(fileName.data()),
      fileName.size() * sizeof(WCHAR), index, aBaton);
  return true;
}

ScaledFontDWrite::InstanceData::InstanceData(
    const wr::FontInstanceOptions* aOptions,
    const wr::FontInstancePlatformOptions* aPlatformOptions)
    : mUseEmbeddedBitmap(false),
      mForceGDIMode(false),
      mGamma(2.2f),
      mContrast(1.0f) {
  if (aOptions) {
    if (aOptions->flags & wr::FontInstanceFlags_EMBEDDED_BITMAPS) {
      mUseEmbeddedBitmap = true;
    }
    if (aOptions->flags & wr::FontInstanceFlags_FORCE_GDI) {
      mForceGDIMode = true;
    }
  }
  if (aPlatformOptions) {
    mGamma = aPlatformOptions->gamma / 100.0f;
    mContrast = aPlatformOptions->contrast / 100.0f;
  }
}

// Helper for ScaledFontDWrite::GetFontInstanceData: if the font has variation
// axes, get their current values into the aOutput vector.
static void GetVariationsFromFontFace(IDWriteFontFace* aFace,
                                      std::vector<FontVariation>* aOutput) {
  RefPtr<IDWriteFontFace5> ff5;
  aFace->QueryInterface(__uuidof(IDWriteFontFace5),
                        (void**)getter_AddRefs(ff5));
  if (!ff5 || !ff5->HasVariations()) {
    return;
  }

  uint32_t count = ff5->GetFontAxisValueCount();
  if (!count) {
    return;
  }

  RefPtr<IDWriteFontResource> res;
  if (FAILED(ff5->GetFontResource(getter_AddRefs(res)))) {
    return;
  }

  std::vector<DWRITE_FONT_AXIS_VALUE> values(count);
  if (FAILED(ff5->GetFontAxisValues(values.data(), count))) {
    return;
  }

  aOutput->reserve(count);
  for (uint32_t i = 0; i < count; i++) {
    DWRITE_FONT_AXIS_ATTRIBUTES attr = res->GetFontAxisAttributes(i);
    if (attr & DWRITE_FONT_AXIS_ATTRIBUTES_VARIABLE) {
      float v = values[i].value;
      uint32_t t = TRUETYPE_TAG(
          uint8_t(values[i].axisTag), uint8_t(values[i].axisTag >> 8),
          uint8_t(values[i].axisTag >> 16), uint8_t(values[i].axisTag >> 24));
      aOutput->push_back(FontVariation{uint32_t(t), float(v)});
    }
  }
}

bool ScaledFontDWrite::GetFontInstanceData(FontInstanceDataOutput aCb,
                                           void* aBaton) {
  InstanceData instance(this);

  // If the font has variations, get the list of axis values.
  std::vector<FontVariation> variations;
  GetVariationsFromFontFace(mFontFace, &variations);

  aCb(reinterpret_cast<uint8_t*>(&instance), sizeof(instance),
      variations.data(), variations.size(), aBaton);

  return true;
}

bool ScaledFontDWrite::GetWRFontInstanceOptions(
    Maybe<wr::FontInstanceOptions>* aOutOptions,
    Maybe<wr::FontInstancePlatformOptions>* aOutPlatformOptions,
    std::vector<FontVariation>* aOutVariations) {
  wr::FontInstanceOptions options;
  bool useSubpixel = !mParams || mParams->GetClearTypeLevel() != 0.0f;
  options.render_mode = wr::ToFontRenderMode(GetDefaultAAMode(), useSubpixel);
  options.flags = wr::FontInstanceFlags{0};
  if (mFontFace->GetSimulations() & DWRITE_FONT_SIMULATIONS_BOLD) {
    options.flags |= wr::FontInstanceFlags_SYNTHETIC_BOLD;
  }
  if (UseEmbeddedBitmaps()) {
    options.flags |= wr::FontInstanceFlags_EMBEDDED_BITMAPS;
  }
  if (ForceGDIMode()) {
    options.flags |= wr::FontInstanceFlags_FORCE_GDI;
  } else {
    options.flags |= wr::FontInstanceFlags_SUBPIXEL_POSITION;
  }
  if (Factory::GetBGRSubpixelOrder()) {
    options.flags |= wr::FontInstanceFlags_SUBPIXEL_BGR;
  }
  options.bg_color = wr::ToColorU(Color());
  options.synthetic_italics =
      wr::DegreesToSyntheticItalics(GetSyntheticObliqueAngle());

  wr::FontInstancePlatformOptions platformOptions;
  platformOptions.gamma = uint16_t(std::round(mGamma * 100.0f));
  platformOptions.contrast =
      uint16_t(std::round(std::min(mContrast, 1.0f) * 100.0f));

  *aOutOptions = Some(options);
  *aOutPlatformOptions = Some(platformOptions);

  GetVariationsFromFontFace(mFontFace, aOutVariations);

  return true;
}

// Helper for UnscaledFontDWrite::CreateScaledFont: create a clone of the
// given IDWriteFontFace, with specified variation-axis values applied.
// Returns nullptr in case of failure.
static already_AddRefed<IDWriteFontFace5> CreateFaceWithVariations(
    IDWriteFontFace* aFace, const FontVariation* aVariations,
    uint32_t aNumVariations) {
  auto makeDWriteAxisTag = [](uint32_t aTag) {
    return DWRITE_MAKE_FONT_AXIS_TAG((aTag >> 24) & 0xff, (aTag >> 16) & 0xff,
                                     (aTag >> 8) & 0xff, aTag & 0xff);
  };

  RefPtr<IDWriteFontFace5> ff5;
  aFace->QueryInterface(__uuidof(IDWriteFontFace5),
                        (void**)getter_AddRefs(ff5));
  if (!ff5) {
    return nullptr;
  }

  DWRITE_FONT_SIMULATIONS sims = aFace->GetSimulations();
  RefPtr<IDWriteFontResource> res;
  if (FAILED(ff5->GetFontResource(getter_AddRefs(res)))) {
    return nullptr;
  }

  std::vector<DWRITE_FONT_AXIS_VALUE> fontAxisValues;
  fontAxisValues.reserve(aNumVariations);
  for (uint32_t i = 0; i < aNumVariations; i++) {
    DWRITE_FONT_AXIS_VALUE axisValue = {makeDWriteAxisTag(aVariations[i].mTag),
                                        aVariations[i].mValue};
    fontAxisValues.push_back(axisValue);
  }

  RefPtr<IDWriteFontFace5> newFace;
  if (FAILED(res->CreateFontFace(sims, fontAxisValues.data(),
                                 fontAxisValues.size(),
                                 getter_AddRefs(newFace)))) {
    return nullptr;
  }

  return newFace.forget();
}

already_AddRefed<ScaledFont> UnscaledFontDWrite::CreateScaledFont(
    Float aGlyphSize, const uint8_t* aInstanceData,
    uint32_t aInstanceDataLength, const FontVariation* aVariations,
    uint32_t aNumVariations) {
  if (aInstanceDataLength < sizeof(ScaledFontDWrite::InstanceData)) {
    gfxWarning() << "DWrite scaled font instance data is truncated.";
    return nullptr;
  }
  const ScaledFontDWrite::InstanceData& instanceData =
      *reinterpret_cast<const ScaledFontDWrite::InstanceData*>(aInstanceData);

  IDWriteFontFace* face = mFontFace;

  // If variations are required, we create a separate IDWriteFontFace5 with
  // the requested settings applied.
  RefPtr<IDWriteFontFace5> ff5;
  if (aNumVariations) {
    ff5 = CreateFaceWithVariations(mFontFace, aVariations, aNumVariations);
    if (ff5) {
      face = ff5;
    } else {
      gfxWarning() << "Failed to create IDWriteFontFace5 with variations.";
    }
  }

  RefPtr<ScaledFontBase> scaledFont = new ScaledFontDWrite(
      face, this, aGlyphSize, instanceData.mUseEmbeddedBitmap,
      instanceData.mForceGDIMode, nullptr, instanceData.mGamma,
      instanceData.mContrast);

  if (mNeedsCairo && !scaledFont->PopulateCairoScaledFont()) {
    gfxWarning() << "Unable to create cairo scaled font DWrite font.";
    return nullptr;
  }

  return scaledFont.forget();
}

already_AddRefed<ScaledFont> UnscaledFontDWrite::CreateScaledFontFromWRFont(
    Float aGlyphSize, const wr::FontInstanceOptions* aOptions,
    const wr::FontInstancePlatformOptions* aPlatformOptions,
    const FontVariation* aVariations, uint32_t aNumVariations) {
  ScaledFontDWrite::InstanceData instanceData(aOptions, aPlatformOptions);
  return CreateScaledFont(aGlyphSize, reinterpret_cast<uint8_t*>(&instanceData),
                          sizeof(instanceData), aVariations, aNumVariations);
}

AntialiasMode ScaledFontDWrite::GetDefaultAAMode() {
  AntialiasMode defaultMode = GetSystemDefaultAAMode();

  if (defaultMode == AntialiasMode::GRAY) {
    if (!DoGrayscale(mFontFace, mSize)) {
      defaultMode = AntialiasMode::NONE;
    }
  }
  return defaultMode;
}

#ifdef USE_CAIRO_SCALED_FONT
cairo_font_face_t* ScaledFontDWrite::GetCairoFontFace() {
  if (!mFontFace) {
    return nullptr;
  }

  return cairo_dwrite_font_face_create_for_dwrite_fontface(nullptr, mFontFace);
}
#endif

}  // namespace gfx
}  // namespace mozilla