Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1253 insertions, 0 deletions

diff --git a/gfx/thebes/gfxFontEntry.h b/gfx/thebes/gfxFontEntry.h
new file mode 100644
index 0000000000..86d2445d0b
--- /dev/null
+++ b/gfx/thebes/gfxFontEntry.h
@@ -0,0 +1,1253 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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/. */
+
+#ifndef GFX_FONTENTRY_H
+#define GFX_FONTENTRY_H
+
+#include <limits>
+#include <math.h>
+#include <new>
+#include <utility>
+#include "COLRFonts.h"
+#include "ThebesRLBoxTypes.h"
+#include "gfxFontUtils.h"
+#include "gfxFontVariations.h"
+#include "gfxRect.h"
+#include "gfxTypes.h"
+#include "harfbuzz/hb.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/FontPropertyTypes.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/RWLock.h"
+#include "mozilla/TypedEnumBits.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/intl/UnicodeScriptCodes.h"
+#include "nsTHashMap.h"
+#include "nsDebug.h"
+#include "nsHashKeys.h"
+#include "nsISupports.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
+#include "nscore.h"
+
+class FontInfoData;
+class gfxContext;
+class gfxFont;
+class gfxFontFamily;
+class gfxPlatformFontList;
+class gfxSVGGlyphs;
+class gfxUserFontData;
+class nsAtom;
+struct FontListSizes;
+struct gfxFontFeature;
+struct gfxFontStyle;
+enum class eFontPresentation : uint8_t;
+
+namespace IPC {
+template <class P>
+struct ParamTraits;
+}
+
+namespace mozilla {
+class SVGContextPaint;
+namespace fontlist {
+struct Face;
+struct Family;
+}  // namespace fontlist
+}  // namespace mozilla
+
+typedef struct gr_face gr_face;
+typedef struct FT_MM_Var_ FT_MM_Var;
+
+#define NO_FONT_LANGUAGE_OVERRIDE 0
+
+class gfxCharacterMap : public gfxSparseBitSet {
+ public:
+  // gfxCharacterMap instances may be shared across multiple threads via a
+  // global table managed by gfxPlatformFontList. Once a gfxCharacterMap is
+  // inserted in the global table, its mShared flag will be TRUE, and we
+  // cannot safely delete it except from gfxPlatformFontList (which will
+  // use a lock to ensure entries are removed from its table and deleted
+  // safely).
+
+  // AddRef() is pretty much standard. We don't return the refcount as our
+  // users don't care about it.
+  void AddRef() {
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(gfxCharacterMap);
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");
+    [[maybe_unused]] nsrefcnt count = ++mRefCnt;
+    NS_LOG_ADDREF(this, count, "gfxCharacterMap", sizeof(*this));
+  }
+
+  // Custom Release(): if the object is referenced from the global shared
+  // table, and we're releasing the last *other* reference to it, then we
+  // notify the global table to consider also releasing its ref. (That may
+  // not actually happen, if another thread is racing with us and takes a
+  // new reference, or completes the release first!)
+  void Release() {
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
+    // We can't safely read this after we've decremented mRefCnt, so save it
+    // in a local variable here. Note that the value is never reset to false
+    // once it has been set to true (when recording the cmap in the shared
+    // table), so there's no risk of this resulting in a "false positive" when
+    // tested later. A "false negative" is possible but harmless; it would
+    // just mean we miss an opportunity to release a reference from the shared
+    // cmap table.
+    bool isShared = mShared;
+
+    // Ensure we only access mRefCnt once, for consistency if the object is
+    // being used by multiple threads.
+    nsrefcnt count = --mRefCnt;
+    NS_LOG_RELEASE(this, count, "gfxCharacterMap");
+
+    // If isShared was true, this object has been shared across threads. In
+    // that case, if the refcount went to 1, we notify the shared table so
+    // it can drop its reference and delete the object.
+    if (isShared) {
+      MOZ_ASSERT(count > 0);
+      if (count == 1) {
+        NotifyMaybeReleased(this);
+      }
+      return;
+    }
+
+    // Otherwise, this object hasn't been shared and we can safely delete it
+    // as we must have been holding the only reference. (Note that if we were
+    // holding the only reference, there's no other owner who can have set
+    // mShared to true since we read it above.)
+    if (count == 0) {
+      delete this;
+    }
+  }
+
+  gfxCharacterMap() = default;
+
+  explicit gfxCharacterMap(const gfxSparseBitSet& aOther)
+      : gfxSparseBitSet(aOther) {}
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return gfxSparseBitSet::SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  // hash of the cmap bitvector
+  uint32_t mHash = 0;
+
+  // if cmap is built on the fly it's never shared
+  bool mBuildOnTheFly = false;
+
+  // Character map is shared globally. This can only be set by the thread that
+  // originally created the map, as no other thread can get a reference until
+  // it has been shared via the global table.
+  bool mShared = false;
+
+ protected:
+  friend class gfxPlatformFontList;
+
+  // Destructor should not be called except via Release().
+  // (Note that our "friend" gfxPlatformFontList also accesses this from its
+  // MaybeRemoveCmap method.)
+  ~gfxCharacterMap() = default;
+
+  nsrefcnt RefCount() const { return mRefCnt; }
+
+  void CalcHash() { mHash = GetChecksum(); }
+
+  static void NotifyMaybeReleased(gfxCharacterMap* aCmap);
+
+  // Only used when clearing the shared-cmap hashtable during shutdown.
+  void ClearSharedFlag() {
+    MOZ_ASSERT(NS_IsMainThread());
+    mShared = false;
+  }
+
+  mozilla::ThreadSafeAutoRefCnt mRefCnt;
+
+ private:
+  gfxCharacterMap(const gfxCharacterMap&) = delete;
+  gfxCharacterMap& operator=(const gfxCharacterMap&) = delete;
+};
+
+// Info on an individual font feature, for reporting available features
+// to DevTools via the GetFeatureInfo method.
+struct gfxFontFeatureInfo {
+  uint32_t mTag;
+  uint32_t mScript;
+  uint32_t mLangSys;
+};
+
+class gfxFontEntryCallbacks;
+
+class gfxFontEntry {
+ public:
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+  typedef mozilla::intl::Script Script;
+  typedef mozilla::FontWeight FontWeight;
+  typedef mozilla::FontSlantStyle FontSlantStyle;
+  typedef mozilla::FontStretch FontStretch;
+  typedef mozilla::WeightRange WeightRange;
+  typedef mozilla::SlantStyleRange SlantStyleRange;
+  typedef mozilla::StretchRange StretchRange;
+
+  // Used by stylo
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(gfxFontEntry)
+
+  explicit gfxFontEntry(const nsACString& aName, bool aIsStandardFace = false);
+
+  gfxFontEntry() = delete;
+  gfxFontEntry(const gfxFontEntry&) = delete;
+  gfxFontEntry& operator=(const gfxFontEntry&) = delete;
+
+  // Create a new entry that refers to the same font as this, but without
+  // additional state that may have been set up (such as family name).
+  // (This is only to be used for system fonts in the platform font list,
+  // not user fonts.)
+  virtual gfxFontEntry* Clone() const = 0;
+
+  // unique name for the face, *not* the family; not necessarily the
+  // "real" or user-friendly name, may be an internal identifier
+  const nsCString& Name() const { return mName; }
+
+  // family name
+  const nsCString& FamilyName() const { return mFamilyName; }
+
+  // The following two methods may be relatively expensive, as they
+  // will (usually, except on Linux) load and parse the 'name' table;
+  // they are intended only for the font-inspection API, not for
+  // perf-critical layout/drawing work.
+
+  // The "real" name of the face, if available from the font resource;
+  // returns Name() if nothing better is available.
+  virtual nsCString RealFaceName();
+
+  WeightRange Weight() const { return mWeightRange; }
+  StretchRange Stretch() const { return mStretchRange; }
+  SlantStyleRange SlantStyle() const { return mStyleRange; }
+
+  bool IsUserFont() const { return mIsDataUserFont || mIsLocalUserFont; }
+  bool IsLocalUserFont() const { return mIsLocalUserFont; }
+  bool IsFixedPitch() const { return mFixedPitch; }
+  bool IsItalic() const { return SlantStyle().Min().IsItalic(); }
+  bool IsOblique() const { return SlantStyle().Min().IsOblique(); }
+  bool IsUpright() const { return SlantStyle().Min().IsNormal(); }
+  inline bool SupportsItalic();  // defined below, because of RangeFlags use
+  inline bool SupportsBold();
+  inline bool MayUseSyntheticSlant();
+  bool IgnoreGDEF() const { return mIgnoreGDEF; }
+  bool IgnoreGSUB() const { return mIgnoreGSUB; }
+
+  // Return whether the face corresponds to "normal" CSS style properties:
+  //    font-style: normal;
+  //    font-weight: normal;
+  //    font-stretch: normal;
+  // If this is false, we might want to fall back to a different face and
+  // possibly apply synthetic styling.
+  bool IsNormalStyle() const {
+    return IsUpright() && Weight().Min() <= FontWeight::NORMAL &&
+           Weight().Max() >= FontWeight::NORMAL &&
+           Stretch().Min() <= FontStretch::NORMAL &&
+           Stretch().Max() >= FontStretch::NORMAL;
+  }
+
+  // whether a feature is supported by the font (limited to a small set
+  // of features for which some form of fallback needs to be implemented)
+  virtual bool SupportsOpenTypeFeature(Script aScript, uint32_t aFeatureTag);
+  bool SupportsGraphiteFeature(uint32_t aFeatureTag);
+
+  // returns a set containing all input glyph ids for a given feature
+  const hb_set_t* InputsForOpenTypeFeature(Script aScript,
+                                           uint32_t aFeatureTag);
+
+  virtual bool HasFontTable(uint32_t aTableTag);
+
+  inline bool HasGraphiteTables() {
+    LazyFlag flag = mHasGraphiteTables;
+    if (flag == LazyFlag::Uninitialized) {
+      flag = CheckForGraphiteTables() ? LazyFlag::Yes : LazyFlag::No;
+      mHasGraphiteTables = flag;
+    }
+    return flag == LazyFlag::Yes;
+  }
+
+  inline bool HasCmapTable() {
+    if (!mCharacterMap && !mShmemCharacterMap) {
+      ReadCMAP();
+      NS_ASSERTION(mCharacterMap || mShmemCharacterMap,
+                   "failed to initialize character map");
+    }
+    return mHasCmapTable;
+  }
+
+  inline bool HasCharacter(uint32_t ch) {
+    if (mShmemCharacterMap) {
+      return GetShmemCharacterMap()->test(ch);
+    }
+    if (mCharacterMap) {
+      if (mShmemFace && TrySetShmemCharacterMap()) {
+        // Forget our temporary local copy, now we can use the shared cmap
+        auto* oldCmap = mCharacterMap.exchange(nullptr);
+        NS_IF_RELEASE(oldCmap);
+        return GetShmemCharacterMap()->test(ch);
+      }
+      if (GetCharacterMap()->test(ch)) {
+        return true;
+      }
+    }
+    return TestCharacterMap(ch);
+  }
+
+  virtual bool SkipDuringSystemFallback() { return false; }
+  void EnsureUVSMapInitialized();
+  uint16_t GetUVSGlyph(uint32_t aCh, uint32_t aVS);
+
+  // All concrete gfxFontEntry subclasses (except gfxUserFontEntry) need
+  // to override this, otherwise the font will never be used as it will
+  // be considered to support no characters.
+  // ReadCMAP() must *always* set the mCharacterMap pointer to a valid
+  // gfxCharacterMap, even if empty, as other code assumes this pointer
+  // can be safely dereferenced.
+  virtual nsresult ReadCMAP(FontInfoData* aFontInfoData = nullptr);
+
+  bool TryGetSVGData(const gfxFont* aFont);
+  bool HasSVGGlyph(uint32_t aGlyphId);
+  bool GetSVGGlyphExtents(DrawTarget* aDrawTarget, uint32_t aGlyphId,
+                          gfxFloat aSize, gfxRect* aResult);
+  void RenderSVGGlyph(gfxContext* aContext, uint32_t aGlyphId,
+                      mozilla::SVGContextPaint* aContextPaint);
+  // Call this when glyph geometry or rendering has changed
+  // (e.g. animated SVG glyphs)
+  void NotifyGlyphsChanged();
+
+  bool TryGetColorGlyphs();
+
+  bool HasColorBitmapTable() {
+    LazyFlag flag = mHasColorBitmapTable;
+    if (flag == LazyFlag::Uninitialized) {
+      flag = HasFontTable(TRUETYPE_TAG('C', 'B', 'D', 'T')) ||
+                     HasFontTable(TRUETYPE_TAG('s', 'b', 'i', 'x'))
+                 ? LazyFlag::Yes
+                 : LazyFlag::No;
+      mHasColorBitmapTable = flag;
+    }
+    return flag == LazyFlag::Yes;
+  }
+
+  // Access to raw font table data (needed for Harfbuzz):
+  // returns a pointer to data owned by the fontEntry or the OS,
+  // which will remain valid until the blob is destroyed.
+  // The data MUST be treated as read-only; we may be getting a
+  // reference to a shared system font cache.
+  //
+  // The default implementation uses CopyFontTable to get the data
+  // into a byte array, and maintains a cache of loaded tables.
+  //
+  // Subclasses should override this if they can provide more efficient
+  // access than copying table data into our own buffers.
+  //
+  // Get blob that encapsulates a specific font table, or nullptr if
+  // the table doesn't exist in the font.
+  //
+  // Caller is responsible to call hb_blob_destroy() on the returned blob
+  // (if non-nullptr) when no longer required. For transient access to a
+  // table, use of AutoTable (below) is generally preferred.
+  virtual hb_blob_t* GetFontTable(uint32_t aTag);
+
+  // Stack-based utility to return a specified table, automatically releasing
+  // the blob when the AutoTable goes out of scope.
+  class AutoTable {
+   public:
+    AutoTable(gfxFontEntry* aFontEntry, uint32_t aTag) {
+      mBlob = aFontEntry->GetFontTable(aTag);
+    }
+    ~AutoTable() { hb_blob_destroy(mBlob); }
+    operator hb_blob_t*() const { return mBlob; }
+
+   private:
+    hb_blob_t* mBlob;
+    // not implemented:
+    AutoTable(const AutoTable&) = delete;
+    AutoTable& operator=(const AutoTable&) = delete;
+  };
+
+  // Return a font instance for a particular style. This may be a newly-
+  // created instance, or a font already in the global cache.
+  // We can't return a UniquePtr here, because we may be returning a shared
+  // cached instance; but we also don't return already_AddRefed, because
+  // the caller may only need to use the font temporarily and doesn't need
+  // a strong reference.
+  already_AddRefed<gfxFont> FindOrMakeFont(
+      const gfxFontStyle* aStyle, gfxCharacterMap* aUnicodeRangeMap = nullptr);
+
+  // Get an existing font table cache entry in aBlob if it has been
+  // registered, or return false if not.  Callers must call
+  // hb_blob_destroy on aBlob if true is returned.
+  //
+  // Note that some gfxFont implementations may not call this at all,
+  // if it is more efficient to get the table from the OS at that level.
+  bool GetExistingFontTable(uint32_t aTag, hb_blob_t** aBlob);
+
+  // Elements of aTable are transferred (not copied) to and returned in a
+  // new hb_blob_t which is registered on the gfxFontEntry, but the initial
+  // reference is owned by the caller.  Removing the last reference
+  // unregisters the table from the font entry.
+  //
+  // Pass nullptr for aBuffer to indicate that the table is not present and
+  // nullptr will be returned.  Also returns nullptr on OOM.
+  hb_blob_t* ShareFontTableAndGetBlob(uint32_t aTag, nsTArray<uint8_t>* aTable);
+
+  // Get the font's unitsPerEm from the 'head' table, in the case of an
+  // sfnt resource. Will return kInvalidUPEM for non-sfnt fonts,
+  // if present on the platform.
+  uint16_t UnitsPerEm();
+  enum {
+    kMinUPEM = 16,     // Limits on valid unitsPerEm range, from the
+    kMaxUPEM = 16384,  // OpenType spec
+    kInvalidUPEM = uint16_t(-1)
+  };
+
+  // Shaper face accessors:
+  // NOTE that harfbuzz and graphite handle ownership/lifetime of the face
+  // object in completely different ways.
+
+  // Create a HarfBuzz face corresponding to this font file.
+  // Our reference to the underlying hb_face_t will be released when the
+  // returned AutoHBFace goes out of scope, but the hb_face_t itself may
+  // be kept alive by other references (e.g. if an hb_font_t has been
+  // instantiated for it).
+  class MOZ_STACK_CLASS AutoHBFace {
+   public:
+    explicit AutoHBFace(hb_face_t* aFace) : mFace(aFace) {}
+    ~AutoHBFace() { hb_face_destroy(mFace); }
+
+    operator hb_face_t*() const { return mFace; }
+
+    // Not default-constructible, not copyable.
+    AutoHBFace() = delete;
+    AutoHBFace(const AutoHBFace&) = delete;
+    AutoHBFace& operator=(const AutoHBFace&) = delete;
+
+   private:
+    hb_face_t* mFace;
+  };
+
+  AutoHBFace GetHBFace() {
+    return AutoHBFace(hb_face_create_for_tables(HBGetTable, this, nullptr));
+  }
+
+  // Get the sandbox instance that graphite is running in.
+  rlbox_sandbox_gr* GetGrSandbox();
+
+  // Register and get the callback handle for the glyph advance firefox callback
+  // Since the sandbox instance is shared with multiple test shapers, callback
+  // registration must be handled centrally to ensure multiple instances don't
+  // register the same callback.
+  sandbox_callback_gr<float (*)(const void*, uint16_t)>*
+  GetGrSandboxAdvanceCallbackHandle();
+
+  // Get Graphite face corresponding to this font file.
+  // Caller must call gfxFontEntry::ReleaseGrFace when finished with it.
+  // Graphite is run in a sandbox
+  tainted_opaque_gr<gr_face*> GetGrFace();
+  void ReleaseGrFace(tainted_opaque_gr<gr_face*> aFace);
+
+  // Does the font have graphite contextuals that involve the space glyph
+  // (and therefore we should bypass the word cache)?
+  // Since this function inspects data from libGraphite stored in sandbox memory
+  // it can only return a "hint" to the correct return value. This is because
+  // a compromised libGraphite could change the sandbox memory maliciously at
+  // any moment. The caller must ensure the calling code performs safe actions
+  // independent of the value returned, to unwrap this return.
+  tainted_boolean_hint HasGraphiteSpaceContextuals();
+
+  // Release any SVG-glyphs document this font may have loaded.
+  void DisconnectSVG();
+
+  // Called to notify that aFont is being destroyed. Needed when we're tracking
+  // the fonts belonging to this font entry.
+  void NotifyFontDestroyed(gfxFont* aFont);
+
+  // For memory reporting of the platform font list.
+  virtual void AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      FontListSizes* aSizes) const;
+  virtual void AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      FontListSizes* aSizes) const;
+
+  // Used for reporting on individual font entries in the user font cache,
+  // which are not present in the platform font list.
+  size_t ComputedSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  // Used when checking for complex script support, to mask off cmap ranges
+  struct ScriptRange {
+    uint32_t rangeStart;
+    uint32_t rangeEnd;
+    uint32_t numTags;  // number of entries in the tags[] array
+    hb_tag_t tags[3];  // up to three OpenType script tags to check
+  };
+
+  bool SupportsScriptInGSUB(const hb_tag_t* aScriptTags, uint32_t aNumTags);
+
+  /**
+   * Font-variation query methods.
+   *
+   * Font backends that don't support variations should provide empty
+   * implementations.
+   */
+  virtual bool HasVariations() = 0;
+
+  virtual void GetVariationAxes(
+      nsTArray<gfxFontVariationAxis>& aVariationAxes) = 0;
+
+  virtual void GetVariationInstances(
+      nsTArray<gfxFontVariationInstance>& aInstances) = 0;
+
+  bool HasBoldVariableWeight();
+  bool HasItalicVariation();
+  bool HasSlantVariation();
+  bool HasOpticalSize();
+
+  void CheckForVariationAxes();
+
+  // Set up the entry's weight/stretch/style ranges according to axes found
+  // by GetVariationAxes (for installed fonts; do NOT call this for user
+  // fonts, where the ranges are provided by @font-face descriptors).
+  void SetupVariationRanges();
+
+  // Get variation axis settings that should be used to implement a particular
+  // font style using this resource.
+  void GetVariationsForStyle(nsTArray<gfxFontVariation>& aResult,
+                             const gfxFontStyle& aStyle);
+
+  // Get the font's list of features (if any) for DevTools support.
+  void GetFeatureInfo(nsTArray<gfxFontFeatureInfo>& aFeatureInfo);
+
+  // This is only called on platforms where we use FreeType.
+  virtual FT_MM_Var* GetMMVar() { return nullptr; }
+
+  // Return true if the font has a 'trak' table (and we can successfully
+  // interpret it), otherwise false. This will load and cache the table
+  // the first time it is called.
+  bool HasTrackingTable();
+
+  // Return the tracking (in font units) to be applied for the given size.
+  // (This is a floating-point number because of possible interpolation.)
+  float TrackingForCSSPx(float aSize) const;
+
+  mozilla::gfx::Rect GetFontExtents(float aFUnitScaleFactor) const {
+    // Flip the y-axis here to match the orientation of Gecko's coordinates.
+    return mozilla::gfx::Rect(float(mXMin) * aFUnitScaleFactor,
+                              float(-mYMax) * aFUnitScaleFactor,
+                              float(mXMax - mXMin) * aFUnitScaleFactor,
+                              float(mYMax - mYMin) * aFUnitScaleFactor);
+  }
+
+  nsCString mName;
+  nsCString mFamilyName;
+
+  // These are mutable so that we can take a read lock within a const method.
+  mutable mozilla::RWLock mLock;
+  mutable mozilla::Mutex mFeatureInfoLock;
+
+  mozilla::Atomic<gfxCharacterMap*> mCharacterMap;  // strong ref
+  gfxCharacterMap* GetCharacterMap() const { return mCharacterMap; }
+
+  mozilla::fontlist::Face* mShmemFace = nullptr;
+
+  mozilla::Atomic<const SharedBitSet*> mShmemCharacterMap;
+  const SharedBitSet* GetShmemCharacterMap() const {
+    return mShmemCharacterMap;
+  }
+
+  mozilla::Atomic<const uint8_t*> mUVSData;
+  const uint8_t* GetUVSData() const { return mUVSData; }
+
+  mozilla::UniquePtr<gfxUserFontData> mUserFontData;
+
+  mozilla::Atomic<gfxSVGGlyphs*> mSVGGlyphs;
+  gfxSVGGlyphs* GetSVGGlyphs() const { return mSVGGlyphs; }
+
+  // list of gfxFonts that are using SVG glyphs
+  nsTArray<const gfxFont*> mFontsUsingSVGGlyphs MOZ_GUARDED_BY(mLock);
+  nsTArray<gfxFontFeature> mFeatureSettings;
+  nsTArray<gfxFontVariation> mVariationSettings;
+
+  mozilla::UniquePtr<nsTHashMap<nsUint32HashKey, bool>> mSupportedFeatures
+      MOZ_GUARDED_BY(mFeatureInfoLock);
+  mozilla::UniquePtr<nsTHashMap<nsUint32HashKey, hb_set_t*>> mFeatureInputs
+      MOZ_GUARDED_BY(mFeatureInfoLock);
+
+  // Color Layer font support. These tables are inert once loaded, so we don't
+  // need to hold a lock when reading them.
+  mozilla::Atomic<hb_blob_t*> mCOLR;
+  mozilla::Atomic<hb_blob_t*> mCPAL;
+  hb_blob_t* GetCOLR() const { return mCOLR; }
+  hb_blob_t* GetCPAL() const { return mCPAL; }
+
+  // bitvector of substitution space features per script, one each
+  // for default and non-default features
+  uint32_t mDefaultSubSpaceFeatures[(int(Script::NUM_SCRIPT_CODES) + 31) / 32];
+  uint32_t
+      mNonDefaultSubSpaceFeatures[(int(Script::NUM_SCRIPT_CODES) + 31) / 32];
+
+  mozilla::Atomic<uint32_t> mUVSOffset;
+
+  uint32_t mLanguageOverride = NO_FONT_LANGUAGE_OVERRIDE;
+
+  WeightRange mWeightRange = WeightRange(FontWeight::FromInt(500));
+  StretchRange mStretchRange = StretchRange(FontStretch::NORMAL);
+  SlantStyleRange mStyleRange = SlantStyleRange(FontSlantStyle::NORMAL);
+
+  // Font metrics overrides (as multiples of used font size); negative values
+  // indicate no override to be applied.
+  float mAscentOverride = -1.0;
+  float mDescentOverride = -1.0;
+  float mLineGapOverride = -1.0;
+
+  // Scaling factor to be applied to the font size.
+  float mSizeAdjust = 1.0;
+
+  // For user fonts (only), we need to record whether or not weight/stretch/
+  // slant variations should be clamped to the range specified in the entry
+  // properties. When the @font-face rule omitted one or more of these
+  // descriptors, it is treated as the initial value for font-matching (and
+  // so that is what we record in the font entry), but when rendering the
+  // range is NOT clamped.
+  enum class RangeFlags : uint16_t {
+    eNoFlags = 0,
+    eAutoWeight = (1 << 0),
+    eAutoStretch = (1 << 1),
+    eAutoSlantStyle = (1 << 2),
+
+    // Flag to record whether the face has a variable "wght" axis
+    // that supports "bold" values, used to disable the application
+    // of synthetic-bold effects.
+    eBoldVariableWeight = (1 << 3),
+    // Whether the face has an 'ital' axis.
+    eItalicVariation = (1 << 4),
+    // Whether the face has a 'slnt' axis.
+    eSlantVariation = (1 << 5),
+
+    // Flags to record if the face uses a non-CSS-compatible scale
+    // for weight and/or stretch, in which case we won't map the
+    // properties to the variation axes (though they can still be
+    // explicitly set using font-variation-settings).
+    eNonCSSWeight = (1 << 6),
+    eNonCSSStretch = (1 << 7),
+
+    // Whether the font has an 'opsz' axis.
+    eOpticalSize = (1 << 8)
+  };
+  RangeFlags mRangeFlags = RangeFlags::eNoFlags;
+
+  bool mFixedPitch : 1;
+  bool mIsBadUnderlineFont : 1;
+  bool mIsUserFontContainer : 1;  // userfont entry
+  bool mIsDataUserFont : 1;       // platform font entry (data)
+  bool mIsLocalUserFont : 1;      // platform font entry (local)
+  bool mStandardFace : 1;
+  bool mIgnoreGDEF : 1;
+  bool mIgnoreGSUB : 1;
+  bool mSkipDefaultFeatureSpaceCheck : 1;
+
+  mozilla::Atomic<bool> mSVGInitialized;
+  mozilla::Atomic<bool> mHasCmapTable;
+  mozilla::Atomic<bool> mGrFaceInitialized;
+  mozilla::Atomic<bool> mCheckedForColorGlyph;
+  mozilla::Atomic<bool> mCheckedForVariationAxes;
+
+  // Atomic flags that are lazily evaluated - initially set to UNINITIALIZED,
+  // changed to NO or YES once we determine the actual value.
+  enum class LazyFlag : uint8_t { Uninitialized = 0xff, No = 0, Yes = 1 };
+
+  std::atomic<LazyFlag> mSpaceGlyphIsInvisible;
+  std::atomic<LazyFlag> mHasGraphiteTables;
+  std::atomic<LazyFlag> mHasGraphiteSpaceContextuals;
+  std::atomic<LazyFlag> mHasColorBitmapTable;
+
+  enum class SpaceFeatures : uint8_t {
+    Uninitialized = 0xff,
+    None = 0,
+    HasFeatures = 1 << 0,
+    Kerning = 1 << 1,
+    NonKerning = 1 << 2
+  };
+
+  std::atomic<SpaceFeatures> mHasSpaceFeatures;
+
+ protected:
+  friend class gfxPlatformFontList;
+  friend class gfxFontFamily;
+  friend class gfxUserFontEntry;
+
+  // Protected destructor, to discourage deletion outside of Release():
+  virtual ~gfxFontEntry();
+
+  virtual gfxFont* CreateFontInstance(const gfxFontStyle* aFontStyle) = 0;
+
+  inline bool CheckForGraphiteTables() {
+    return HasFontTable(TRUETYPE_TAG('S', 'i', 'l', 'f'));
+  }
+
+  // Copy a font table into aBuffer.
+  // The caller will be responsible for ownership of the data.
+  virtual nsresult CopyFontTable(uint32_t aTableTag,
+                                 nsTArray<uint8_t>& aBuffer) {
+    MOZ_ASSERT_UNREACHABLE(
+        "forgot to override either GetFontTable or "
+        "CopyFontTable?");
+    return NS_ERROR_FAILURE;
+  }
+
+  // Helper for HasTrackingTable; check/parse the table and cache pointers
+  // to the subtables we need. Returns false on failure, in which case the
+  // table is unusable.
+  bool ParseTrakTable() MOZ_REQUIRES(mLock);
+
+  // lookup the cmap in cached font data
+  virtual already_AddRefed<gfxCharacterMap> GetCMAPFromFontInfo(
+      FontInfoData* aFontInfoData, uint32_t& aUVSOffset);
+
+  // helper for HasCharacter(), which is what client code should call
+  virtual bool TestCharacterMap(uint32_t aCh);
+
+  // Try to set mShmemCharacterMap, based on the char map in mShmemFace;
+  // return true if successful, false if it remains null (maybe the parent
+  // hasn't handled our SetCharacterMap message yet).
+  bool TrySetShmemCharacterMap();
+
+  // Helper for gfxPlatformFontList::CreateFontEntry methods: set properties
+  // of the gfxFontEntry based on shared Face and Family records.
+  void InitializeFrom(mozilla::fontlist::Face* aFace,
+                      const mozilla::fontlist::Family* aFamily);
+
+  // Shaper-specific face objects, shared by all instantiations of the same
+  // physical font, regardless of size.
+  // Usually, only one of these will actually be created for any given font
+  // entry, depending on the font tables that are present.
+
+  // hb_face_t is refcounted internally, so each shaper that's using it will
+  // bump the ref count when it acquires the face, and "destroy" (release) it
+  // in its destructor. The font entry has only this non-owning reference to
+  // the face; when the face is deleted, it will tell the font entry to forget
+  // it, so that a new face will be created next time it is needed.
+  mozilla::Atomic<hb_face_t*> mHBFace;
+
+  static hb_blob_t* HBGetTable(hb_face_t* face, uint32_t aTag, void* aUserData);
+
+  // Callback that the hb_face will use to tell us when it is being deleted.
+  static void HBFaceDeletedCallback(void* aUserData);
+
+  // All libGraphite functionality is sandboxed in an rlbox sandbox. This
+  // contains data for the sandbox instance.
+  // Currently graphite shaping is only supported on the main thread.
+  struct GrSandboxData;
+  GrSandboxData* mSandboxData = nullptr;
+
+  // gr_face is -not- refcounted, so it will be owned directly by the font
+  // entry, and we'll keep a count of how many references we've handed out;
+  // each shaper is responsible to call ReleaseGrFace on its entry when
+  // finished with it, so that we know when it can be deleted.
+  tainted_opaque_gr<gr_face*> mGrFace;
+
+  // For AAT font, a strong reference to the 'trak' table (if present).
+  hb_blob_t* const kTrakTableUninitialized = (hb_blob_t*)(intptr_t(-1));
+  mozilla::Atomic<hb_blob_t*> mTrakTable;
+  hb_blob_t* GetTrakTable() const { return mTrakTable; }
+  bool TrakTableInitialized() const {
+    return mTrakTable != kTrakTableUninitialized;
+  }
+
+  // Cached pointers to tables within 'trak', initialized by ParseTrakTable.
+  // This data is inert once loaded, so locking is not required to read it.
+  const mozilla::AutoSwap_PRInt16* mTrakValues = nullptr;
+  const mozilla::AutoSwap_PRInt32* mTrakSizeTable = nullptr;
+
+  // number of current users of this entry's mGrFace
+  nsrefcnt mGrFaceRefCnt = 0;
+
+  friend class gfxFontEntryCallbacks;
+
+  // For memory reporting: size of user-font data belonging to this entry.
+  // We record this in the font entry because the actual data block may be
+  // handed over to platform APIs, so that it would become difficult (and
+  // platform-specific) to measure it directly at report-gathering time.
+  uint32_t mComputedSizeOfUserFont = 0;
+
+  // Font's unitsPerEm from the 'head' table, if available (will be set to
+  // kInvalidUPEM for non-sfnt font formats)
+  uint16_t mUnitsPerEm = 0;
+
+  uint16_t mNumTrakSizes = 0;
+
+  // Font extents in FUnits. (To be set from the 'head' table; default to
+  // "huge" to avoid any clipping if real extents not available.)
+  int16_t mXMin = std::numeric_limits<int16_t>::min();
+  int16_t mYMin = std::numeric_limits<int16_t>::min();
+  int16_t mXMax = std::numeric_limits<int16_t>::max();
+  int16_t mYMax = std::numeric_limits<int16_t>::max();
+
+ private:
+  /**
+   * Font table hashtable, to support GetFontTable for harfbuzz.
+   *
+   * The harfbuzz shaper (and potentially other clients) needs access to raw
+   * font table data. This needs to be cached so that it can be used
+   * repeatedly (each time we construct a text run; in some cases, for
+   * each character/glyph within the run) without re-fetching large tables
+   * every time.
+   *
+   * Because we may instantiate many gfxFonts for the same physical font
+   * file (at different sizes), we should ensure that they can share a
+   * single cached copy of the font tables. To do this, we implement table
+   * access and sharing on the fontEntry rather than the font itself.
+   *
+   * The default implementation uses GetFontTable() to read font table
+   * data into byte arrays, and wraps them in blobs which are registered in
+   * a hashtable.  The hashtable can then return pre-existing blobs to
+   * harfbuzz.
+   *
+   * Harfbuzz will "destroy" the blobs when it is finished with them.  When
+   * the last blob reference is removed, the FontTableBlobData user data
+   * will remove the blob from the hashtable if still registered.
+   */
+
+  class FontTableBlobData;
+
+  /**
+   * FontTableHashEntry manages the entries of hb_blob_t's containing font
+   * table data.
+   *
+   * This is used to share font tables across fonts with the same
+   * font entry (but different sizes) for use by HarfBuzz.  The hashtable
+   * does not own a strong reference to the blob, but keeps a weak pointer,
+   * managed by FontTableBlobData.  Similarly FontTableBlobData keeps only a
+   * weak pointer to the hashtable, managed by FontTableHashEntry.
+   */
+
+  class FontTableHashEntry : public nsUint32HashKey {
+   public:
+    // Declarations for nsTHashtable
+
+    typedef nsUint32HashKey KeyClass;
+    typedef KeyClass::KeyType KeyType;
+    typedef KeyClass::KeyTypePointer KeyTypePointer;
+
+    explicit FontTableHashEntry(KeyTypePointer aTag)
+        : KeyClass(aTag), mSharedBlobData(nullptr), mBlob(nullptr) {}
+
+    // NOTE: This assumes the new entry belongs to the same hashtable as
+    // the old, because the mHashtable pointer in mSharedBlobData (if
+    // present) will not be updated.
+    FontTableHashEntry(FontTableHashEntry&& toMove)
+        : KeyClass(std::move(toMove)),
+          mSharedBlobData(std::move(toMove.mSharedBlobData)),
+          mBlob(std::move(toMove.mBlob)) {
+      toMove.mSharedBlobData = nullptr;
+      toMove.mBlob = nullptr;
+    }
+
+    ~FontTableHashEntry() { Clear(); }
+
+    // FontTable/Blob API
+
+    // Transfer (not copy) elements of aTable to a new hb_blob_t and
+    // return ownership to the caller.  A weak reference to the blob is
+    // recorded in the hashtable entry so that others may use the same
+    // table.
+    hb_blob_t* ShareTableAndGetBlob(
+        nsTArray<uint8_t>&& aTable,
+        nsTHashtable<FontTableHashEntry>* aHashtable);
+
+    // Return a strong reference to the blob.
+    // Callers must hb_blob_destroy the returned blob.
+    hb_blob_t* GetBlob() const;
+
+    void Clear();
+
+    size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+   private:
+    static void DeleteFontTableBlobData(void* aBlobData);
+    // not implemented
+    FontTableHashEntry& operator=(FontTableHashEntry& toCopy);
+
+    FontTableBlobData* mSharedBlobData;
+    hb_blob_t* mBlob;
+  };
+
+  using FontTableCache = nsTHashtable<FontTableHashEntry>;
+  mozilla::Atomic<FontTableCache*> mFontTableCache;
+  FontTableCache* GetFontTableCache() const { return mFontTableCache; }
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(gfxFontEntry::RangeFlags)
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(gfxFontEntry::SpaceFeatures)
+
+inline bool gfxFontEntry::SupportsItalic() {
+  return SlantStyle().Max().IsItalic() ||
+         ((mRangeFlags & RangeFlags::eAutoSlantStyle) ==
+              RangeFlags::eAutoSlantStyle &&
+          HasItalicVariation());
+}
+
+inline bool gfxFontEntry::SupportsBold() {
+  // bold == weights 600 and above
+  // We return true if the face has a max weight descriptor >= 600,
+  // OR if it's a user font with auto-weight (no descriptor) and has
+  // a weight axis that supports values >= 600
+  return Weight().Max().IsBold() ||
+         ((mRangeFlags & RangeFlags::eAutoWeight) == RangeFlags::eAutoWeight &&
+          HasBoldVariableWeight());
+}
+
+inline bool gfxFontEntry::MayUseSyntheticSlant() {
+  if (!IsUpright()) {
+    return false;  // The resource is already non-upright.
+  }
+  if (HasSlantVariation()) {
+    if (mRangeFlags & RangeFlags::eAutoSlantStyle) {
+      return false;
+    }
+    if (!SlantStyle().IsSingle()) {
+      return false;  // The resource has a 'slnt' axis, and has not been
+                     // clamped to just its upright setting.
+    }
+  }
+  return true;
+}
+
+// used when iterating over all fonts looking for a match for a given character
+struct GlobalFontMatch {
+  GlobalFontMatch(uint32_t aCharacter, uint32_t aNextCh,
+                  const gfxFontStyle& aStyle, eFontPresentation aPresentation)
+      : mStyle(aStyle),
+        mCh(aCharacter),
+        mNextCh(aNextCh),
+        mPresentation(aPresentation) {}
+
+  RefPtr<gfxFontEntry> mBestMatch;       // current best match
+  RefPtr<gfxFontFamily> mMatchedFamily;  // the family it belongs to
+  mozilla::fontlist::Family* mMatchedSharedFamily = nullptr;
+  const gfxFontStyle& mStyle;  // style to match
+  const uint32_t mCh;          // codepoint to be matched
+  const uint32_t mNextCh;      // following codepoint (or zero)
+  eFontPresentation mPresentation;
+  uint32_t mCount = 0;               // number of fonts matched
+  uint32_t mCmapsTested = 0;         // number of cmaps tested
+  double mMatchDistance = INFINITY;  // metric indicating closest match
+};
+
+class gfxFontFamily {
+ public:
+  // Used by stylo
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(gfxFontFamily)
+
+  gfxFontFamily(const nsACString& aName, FontVisibility aVisibility)
+      : mName(aName),
+        mLock("gfxFontFamily lock"),
+        mVisibility(aVisibility),
+        mIsSimpleFamily(false),
+        mIsBadUnderlineFamily(false),
+        mSkipDefaultFeatureSpaceCheck(false),
+        mCheckForFallbackFaces(false) {}
+
+  const nsCString& Name() const { return mName; }
+
+  virtual void LocalizedName(nsACString& aLocalizedName);
+  virtual bool HasOtherFamilyNames();
+
+  // See https://bugzilla.mozilla.org/show_bug.cgi?id=835204:
+  // check the font's 'name' table to see if it has a legacy family name
+  // that would have been used by GDI (e.g. to split extra-bold or light
+  // faces in a large family into separate "styled families" because of
+  // GDI's 4-faces-per-family limitation). If found, the styled family
+  // name will be added to the font list's "other family names" table.
+  // Note that the caller must already hold the gfxPlatformFontList lock.
+  bool CheckForLegacyFamilyNames(gfxPlatformFontList* aFontList);
+
+  // Callers must hold a read-lock for as long as they're using the list.
+  const nsTArray<RefPtr<gfxFontEntry>>& GetFontList()
+      MOZ_REQUIRES_SHARED(mLock) {
+    return mAvailableFonts;
+  }
+  void ReadLock() MOZ_ACQUIRE_SHARED(mLock) { mLock.ReadLock(); }
+  void ReadUnlock() MOZ_RELEASE_SHARED(mLock) { mLock.ReadUnlock(); }
+
+  uint32_t FontListLength() const {
+    mozilla::AutoReadLock lock(mLock);
+    return mAvailableFonts.Length();
+  }
+
+  void AddFontEntry(RefPtr<gfxFontEntry> aFontEntry) {
+    mozilla::AutoWriteLock lock(mLock);
+    AddFontEntryLocked(aFontEntry);
+  }
+
+  void AddFontEntryLocked(RefPtr<gfxFontEntry> aFontEntry) MOZ_REQUIRES(mLock) {
+    // Avoid potentially duplicating entries.
+    if (mAvailableFonts.Contains(aFontEntry)) {
+      return;
+    }
+    // bug 589682 - set the IgnoreGDEF flag on entries for Italic faces
+    // of Times New Roman, because of buggy table in those fonts
+    if (aFontEntry->IsItalic() && !aFontEntry->IsUserFont() &&
+        Name().EqualsLiteral("Times New Roman")) {
+      aFontEntry->mIgnoreGDEF = true;
+    }
+    if (aFontEntry->mFamilyName.IsEmpty()) {
+      aFontEntry->mFamilyName = Name();
+    } else {
+      MOZ_ASSERT(aFontEntry->mFamilyName.Equals(Name()));
+    }
+    aFontEntry->mSkipDefaultFeatureSpaceCheck = mSkipDefaultFeatureSpaceCheck;
+    mAvailableFonts.AppendElement(aFontEntry);
+
+    // If we're adding a face to a family that has been marked as "simple",
+    // we need to ensure any null entries are removed, as well as clearing
+    // the flag (which may be set again later).
+    if (mIsSimpleFamily) {
+      mAvailableFonts.RemoveElementsBy([](const auto& font) { return !font; });
+      mIsSimpleFamily = false;
+    }
+  }
+
+  // note that the styles for this family have been added
+  bool HasStyles() const { return mHasStyles; }
+  void SetHasStyles(bool aHasStyles) { mHasStyles = aHasStyles; }
+
+  void SetCheckedForLegacyFamilyNames(bool aChecked) {
+    mCheckedForLegacyFamilyNames = aChecked;
+  }
+
+  // choose a specific face to match a style using CSS font matching
+  // rules (weight matching occurs here).  may return a face that doesn't
+  // precisely match (e.g. normal face when no italic face exists).
+  gfxFontEntry* FindFontForStyle(const gfxFontStyle& aFontStyle,
+                                 bool aIgnoreSizeTolerance = false);
+
+  virtual void FindAllFontsForStyle(const gfxFontStyle& aFontStyle,
+                                    nsTArray<gfxFontEntry*>& aFontEntryList,
+                                    bool aIgnoreSizeTolerance = false);
+
+  // Checks for a matching font within the family; used as part of the font
+  // fallback process.
+  // Note that when this is called, the caller must already be holding the
+  // gfxPlatformFontList lock.
+  void FindFontForChar(GlobalFontMatch* aMatchData);
+
+  // checks all fonts for a matching font within the family
+  void SearchAllFontsForChar(GlobalFontMatch* aMatchData);
+
+  // read in other family names, if any, and use functor to add each into cache
+  virtual void ReadOtherFamilyNames(gfxPlatformFontList* aPlatformFontList);
+
+  // set when other family names have been read in
+  void SetOtherFamilyNamesInitialized() { mOtherFamilyNamesInitialized = true; }
+
+  // Read in other localized family names, fullnames and Postscript names
+  // for all faces and append to lookup tables.
+  // Note that when this is called, the caller must already be holding the
+  // gfxPlatformFontList lock.
+  virtual void ReadFaceNames(gfxPlatformFontList* aPlatformFontList,
+                             bool aNeedFullnamePostscriptNames,
+                             FontInfoData* aFontInfoData = nullptr);
+
+  // Find faces belonging to this family (platform implementations override).
+  // This is a no-op in cases where the family is explicitly populated by other
+  // means, rather than being asked to find its faces via system API.
+  virtual void FindStyleVariationsLocked(FontInfoData* aFontInfoData = nullptr)
+      MOZ_REQUIRES(mLock){};
+  void FindStyleVariations(FontInfoData* aFontInfoData = nullptr) {
+    if (mHasStyles) {
+      return;
+    }
+    mozilla::AutoWriteLock lock(mLock);
+    FindStyleVariationsLocked(aFontInfoData);
+  }
+
+  // search for a specific face using the Postscript name
+  gfxFontEntry* FindFont(const nsACString& aFontName,
+                         const nsCStringComparator& aCmp) const;
+
+  // Read in cmaps for all the faces.
+  // Note that when this is called, the caller must already be holding the
+  // gfxPlatformFontList lock.
+  void ReadAllCMAPs(FontInfoData* aFontInfoData = nullptr);
+
+  bool TestCharacterMap(uint32_t aCh) {
+    if (!mFamilyCharacterMapInitialized) {
+      ReadAllCMAPs();
+    }
+    mozilla::AutoReadLock lock(mLock);
+    return mFamilyCharacterMap.test(aCh);
+  }
+
+  void ResetCharacterMap() MOZ_REQUIRES(mLock) {
+    mFamilyCharacterMap.reset();
+    mFamilyCharacterMapInitialized = false;
+  }
+
+  // mark this family as being in the "bad" underline offset blocklist
+  void SetBadUnderlineFamily() {
+    mozilla::AutoWriteLock lock(mLock);
+    mIsBadUnderlineFamily = true;
+    if (mHasStyles) {
+      SetBadUnderlineFonts();
+    }
+  }
+
+  virtual bool IsSingleFaceFamily() const { return false; }
+
+  bool IsBadUnderlineFamily() const { return mIsBadUnderlineFamily; }
+  bool CheckForFallbackFaces() const { return mCheckForFallbackFaces; }
+
+  // sort available fonts to put preferred (standard) faces towards the end
+  void SortAvailableFonts() MOZ_REQUIRES(mLock);
+
+  // check whether the family fits into the simple 4-face model,
+  // so we can use simplified style-matching;
+  // if so set the mIsSimpleFamily flag (defaults to False before we've checked)
+  void CheckForSimpleFamily() MOZ_REQUIRES(mLock);
+
+  // For memory reporter
+  virtual void AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      FontListSizes* aSizes) const;
+  virtual void AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      FontListSizes* aSizes) const;
+
+#ifdef DEBUG
+  // Only used for debugging checks - does a linear search
+  bool ContainsFace(gfxFontEntry* aFontEntry);
+#endif
+
+  void SetSkipSpaceFeatureCheck(bool aSkipCheck) {
+    mSkipDefaultFeatureSpaceCheck = aSkipCheck;
+  }
+
+  // Check whether this family is appropriate to include in the Preferences
+  // font list for the given langGroup and CSS generic, if the platform lets
+  // us determine this.
+  // Return true if the family should be included in the list, false to omit.
+  // Default implementation returns true for everything, so no filtering
+  // will occur; individual platforms may override.
+  virtual bool FilterForFontList(nsAtom* aLangGroup,
+                                 const nsACString& aGeneric) const {
+    return true;
+  }
+
+  FontVisibility Visibility() const { return mVisibility; }
+  bool IsHidden() const { return Visibility() == FontVisibility::Hidden; }
+  bool IsWebFontFamily() const {
+    return Visibility() == FontVisibility::Webfont;
+  }
+
+ protected:
+  // Protected destructor, to discourage deletion outside of Release():
+  virtual ~gfxFontFamily();
+
+  bool ReadOtherFamilyNamesForFace(gfxPlatformFontList* aPlatformFontList,
+                                   hb_blob_t* aNameTable,
+                                   bool useFullName = false);
+
+  // set whether this font family is in "bad" underline offset blocklist.
+  void SetBadUnderlineFonts() MOZ_REQUIRES(mLock) {
+    for (auto& f : mAvailableFonts) {
+      if (f) {
+        f->mIsBadUnderlineFont = true;
+      }
+    }
+  }
+
+  nsCString mName;
+  nsTArray<RefPtr<gfxFontEntry>> mAvailableFonts MOZ_GUARDED_BY(mLock);
+  gfxSparseBitSet mFamilyCharacterMap MOZ_GUARDED_BY(mLock);
+
+  mutable mozilla::RWLock mLock;
+
+  FontVisibility mVisibility;
+
+  mozilla::Atomic<bool> mOtherFamilyNamesInitialized;
+  mozilla::Atomic<bool> mFaceNamesInitialized;
+  mozilla::Atomic<bool> mHasStyles;
+  mozilla::Atomic<bool> mFamilyCharacterMapInitialized;
+  mozilla::Atomic<bool> mCheckedForLegacyFamilyNames;
+  mozilla::Atomic<bool> mHasOtherFamilyNames;
+
+  bool mIsSimpleFamily : 1 MOZ_GUARDED_BY(mLock);
+  bool mIsBadUnderlineFamily : 1;
+  bool mSkipDefaultFeatureSpaceCheck : 1;
+  bool mCheckForFallbackFaces : 1;  // check other faces for character
+
+  enum {
+    // for "simple" families, the faces are stored in mAvailableFonts
+    // with fixed positions:
+    kRegularFaceIndex = 0,
+    kBoldFaceIndex = 1,
+    kItalicFaceIndex = 2,
+    kBoldItalicFaceIndex = 3,
+    // mask values for selecting face with bold and/or italic attributes
+    kBoldMask = 0x01,
+    kItalicMask = 0x02
+  };
+};
+
+// Wrapper for either a raw pointer to a mozilla::fontlist::Family in the shared
+// font list or a strong pointer to an unshared gfxFontFamily that belongs just
+// to the current process.
+struct FontFamily {
+  FontFamily() = default;
+  FontFamily(const FontFamily& aOther) = default;
+
+  explicit FontFamily(RefPtr<gfxFontFamily>&& aFamily)
+      : mUnshared(std::move(aFamily)) {}
+
+  explicit FontFamily(gfxFontFamily* aFamily) : mUnshared(aFamily) {}
+
+  explicit FontFamily(mozilla::fontlist::Family* aFamily) : mShared(aFamily) {}
+
+  bool operator==(const FontFamily& aOther) const {
+    return mShared == aOther.mShared && mUnshared == aOther.mUnshared;
+  }
+
+  bool IsNull() const { return !mShared && !mUnshared; }
+
+  RefPtr<gfxFontFamily> mUnshared;
+  mozilla::fontlist::Family* mShared = nullptr;
+};
+
+// Struct used in the gfxFontGroup font list to keep track of a font family
+// together with the CSS generic (if any) that was mapped to it in this
+// particular case (so it can be reported to the DevTools font inspector).
+struct FamilyAndGeneric final {
+  FamilyAndGeneric()
+      : mFamily(), mGeneric(mozilla::StyleGenericFontFamily(0)) {}
+  FamilyAndGeneric(const FamilyAndGeneric& aOther) = default;
+  explicit FamilyAndGeneric(gfxFontFamily* aFamily,
+                            mozilla::StyleGenericFontFamily aGeneric =
+                                mozilla::StyleGenericFontFamily(0))
+      : mFamily(aFamily), mGeneric(aGeneric) {}
+  explicit FamilyAndGeneric(RefPtr<gfxFontFamily>&& aFamily,
+                            mozilla::StyleGenericFontFamily aGeneric =
+                                mozilla::StyleGenericFontFamily(0))
+      : mFamily(std::move(aFamily)), mGeneric(aGeneric) {}
+  explicit FamilyAndGeneric(mozilla::fontlist::Family* aFamily,
+                            mozilla::StyleGenericFontFamily aGeneric =
+                                mozilla::StyleGenericFontFamily(0))
+      : mFamily(aFamily), mGeneric(aGeneric) {}
+  explicit FamilyAndGeneric(const FontFamily& aFamily,
+                            mozilla::StyleGenericFontFamily aGeneric =
+                                mozilla::StyleGenericFontFamily(0))
+      : mFamily(aFamily), mGeneric(aGeneric) {}
+
+  bool operator==(const FamilyAndGeneric& aOther) const {
+    return mFamily == aOther.mFamily && mGeneric == aOther.mGeneric;
+  }
+
+  FontFamily mFamily;
+  mozilla::StyleGenericFontFamily mGeneric;
+};
+
+#endif