Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

1 files changed, 2673 insertions, 0 deletions

diff --git a/gfx/thebes/COLRFonts.cpp b/gfx/thebes/COLRFonts.cpp
new file mode 100644
index 0000000000..89ca35661e
--- /dev/null
+++ b/gfx/thebes/COLRFonts.cpp
@@ -0,0 +1,2673 @@
+/* -*- 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/. */
+
+#include "COLRFonts.h"
+#include "gfxFontUtils.h"
+#include "gfxUtils.h"
+#include "harfbuzz/hb.h"
+#include "harfbuzz/hb-ot.h"
+#include "mozilla/gfx/Helpers.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "TextDrawTarget.h"
+
+#include <limits>
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+namespace {  // anonymous namespace for implementation internals
+
+#pragma pack(1)  // ensure no padding is added to the COLR structs
+
+// Alias bigendian-reading types from gfxFontUtils to names used in the spec.
+using int16 = AutoSwap_PRInt16;
+using uint16 = AutoSwap_PRUint16;
+using int32 = AutoSwap_PRInt32;
+using uint32 = AutoSwap_PRUint32;
+using FWORD = AutoSwap_PRInt16;
+using UFWORD = AutoSwap_PRUint16;
+using Offset16 = AutoSwap_PRUint16;
+using Offset24 = AutoSwap_PRUint24;
+using Offset32 = AutoSwap_PRUint32;
+
+struct COLRv1Header;
+struct ClipList;
+struct LayerRecord;
+struct BaseGlyphRecord;
+struct DeltaSetIndexMap;
+struct ItemVariationStore;
+
+struct COLRHeader {
+  uint16 version;
+  uint16 numBaseGlyphRecords;
+  Offset32 baseGlyphRecordsOffset;
+  Offset32 layerRecordsOffset;
+  uint16 numLayerRecords;
+
+  const BaseGlyphRecord* GetBaseGlyphRecords() const {
+    return reinterpret_cast<const BaseGlyphRecord*>(
+        reinterpret_cast<const char*>(this) + baseGlyphRecordsOffset);
+  }
+
+  const LayerRecord* GetLayerRecords() const {
+    return reinterpret_cast<const LayerRecord*>(
+        reinterpret_cast<const char*>(this) + layerRecordsOffset);
+  }
+
+  bool Validate(uint64_t aLength) const;
+};
+
+struct BaseGlyphPaintRecord {
+  uint16 glyphID;
+  Offset32 paintOffset;
+};
+
+struct BaseGlyphList {
+  uint32 numBaseGlyphPaintRecords;
+  // BaseGlyphPaintRecord baseGlyphPaintRecords[numBaseGlyphPaintRecords];
+  const BaseGlyphPaintRecord* baseGlyphPaintRecords() const {
+    return reinterpret_cast<const BaseGlyphPaintRecord*>(this + 1);
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+struct LayerList {
+  uint32 numLayers;
+  // uint32 paintOffsets[numLayers];
+  const uint32* paintOffsets() const {
+    return reinterpret_cast<const uint32*>(this + 1);
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+struct COLRv1Header {
+  COLRHeader base;
+  Offset32 baseGlyphListOffset;
+  Offset32 layerListOffset;
+  Offset32 clipListOffset;
+  Offset32 varIndexMapOffset;
+  Offset32 itemVariationStoreOffset;
+
+  bool Validate(uint64_t aLength) const;
+
+  const BaseGlyphList* baseGlyphList() const {
+    uint32_t offset = baseGlyphListOffset;
+    if (!offset) {
+      return nullptr;
+    }
+    const char* ptr = reinterpret_cast<const char*>(this) + offset;
+    return reinterpret_cast<const struct BaseGlyphList*>(ptr);
+  }
+
+  const LayerList* layerList() const {
+    uint32_t offset = layerListOffset;
+    if (!offset) {
+      return nullptr;
+    }
+    const char* ptr = reinterpret_cast<const char*>(this) + offset;
+    return reinterpret_cast<const LayerList*>(ptr);
+  }
+
+  const struct ClipList* clipList() const {
+    uint32_t offset = clipListOffset;
+    if (!offset) {
+      return nullptr;
+    }
+    const char* ptr = reinterpret_cast<const char*>(this) + offset;
+    return reinterpret_cast<const ClipList*>(ptr);
+  }
+
+  const struct DeltaSetIndexMap* varIndexMap() const {
+    uint32_t offset = varIndexMapOffset;
+    if (!offset) {
+      return nullptr;
+    }
+    const char* ptr = reinterpret_cast<const char*>(this) + offset;
+    return reinterpret_cast<const DeltaSetIndexMap*>(ptr);
+  }
+
+  const struct ItemVariationStore* itemVariationStore() const {
+    uint32_t offset = itemVariationStoreOffset;
+    if (!offset) {
+      return nullptr;
+    }
+    const char* ptr = reinterpret_cast<const char*>(this) + offset;
+    return reinterpret_cast<const ItemVariationStore*>(ptr);
+  }
+
+  const BaseGlyphPaintRecord* GetBaseGlyphPaint(uint32_t aGlyphId) const;
+};
+
+struct PaintState {
+  union {
+    const COLRHeader* v0;
+    const COLRv1Header* v1;
+  } mHeader;
+  const sRGBColor* mPalette;
+  DrawTarget* mDrawTarget;
+  ScaledFont* mScaledFont;
+  const int* mCoords;
+  DrawOptions mDrawOptions;
+  uint32_t mCOLRLength;
+  sRGBColor mCurrentColor;
+  float mFontUnitsToPixels;
+  uint16_t mNumColors;
+  uint16_t mCoordCount;
+  nsTArray<uint32_t>* mVisited;
+
+  const char* COLRv1BaseAddr() const {
+    return reinterpret_cast<const char*>(mHeader.v1);
+  }
+
+  DeviceColor GetColor(uint16_t aPaletteIndex, float aAlpha) const;
+
+  // Convert from FUnits (either integer or Fixed 16.16) to device pixels.
+  template <typename T>
+  float F2P(T aPixels) const {
+    return mFontUnitsToPixels * float(aPixels);
+  }
+};
+
+DeviceColor PaintState::GetColor(uint16_t aPaletteIndex, float aAlpha) const {
+  sRGBColor color;
+  if (aPaletteIndex < mNumColors) {
+    color = mPalette[uint16_t(aPaletteIndex)];
+  } else if (aPaletteIndex == 0xffff) {
+    color = mCurrentColor;
+  } else {  // Palette index out of range! Return transparent black.
+    color = sRGBColor();
+  }
+  color.a *= aAlpha;
+  return ToDeviceColor(color);
+}
+
+static bool DispatchPaint(const PaintState& aState, uint32_t aOffset,
+                          const Rect* aBounds /* may be nullptr if unknown */);
+static UniquePtr<Pattern> DispatchMakePattern(const PaintState& aState,
+                                              uint32_t aOffset);
+static Rect DispatchGetBounds(const PaintState& aState, uint32_t aOffset);
+static Matrix DispatchGetMatrix(const PaintState& aState, uint32_t aOffset);
+
+// Variation-data types
+struct Fixed {
+  enum { kFractionBits = 16 };
+  operator float() const {
+    return float(int32_t(value)) / float(1 << kFractionBits);
+  }
+  int32_t intRepr() const { return int32_t(value); }
+
+ private:
+  int32 value;
+};
+
+struct F2DOT14 {
+  enum { kFractionBits = 14 };
+  operator float() const {
+    return float(int16_t(value)) / float(1 << kFractionBits);
+  }
+  int32_t intRepr() const { return int16_t(value); }
+
+ private:
+  int16 value;
+};
+
+// Saturating addition used for variation indexes to avoid wrap-around.
+static uint32_t SatAdd(uint32_t a, uint32_t b) {
+  if (a <= std::numeric_limits<uint32_t>::max() - b) {
+    return a + b;
+  }
+  return std::numeric_limits<uint32_t>::max();
+}
+
+struct RegionAxisCoordinates {
+  F2DOT14 startCoord;
+  F2DOT14 peakCoord;
+  F2DOT14 endCoord;
+};
+
+struct VariationRegion {
+  // RegionAxisCoordinates regionAxes[axisCount];
+  const RegionAxisCoordinates* regionAxes() const {
+    return reinterpret_cast<const RegionAxisCoordinates*>(this);
+  }
+};
+
+struct VariationRegionList {
+  uint16 axisCount;
+  uint16 regionCount;
+  // VariationRegion variationRegions[regionCount];
+  const char* variationRegionsBase() const {
+    return reinterpret_cast<const char*>(this + 1);
+  }
+  size_t regionSize() const {
+    return uint16_t(axisCount) * sizeof(RegionAxisCoordinates);
+  }
+  const VariationRegion* getRegion(uint16_t i) const {
+    if (i >= uint16_t(regionCount)) {
+      return nullptr;
+    }
+    return reinterpret_cast<const VariationRegion*>(variationRegionsBase() +
+                                                    i * regionSize());
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const {
+    if (variationRegionsBase() - reinterpret_cast<const char*>(aHeader) +
+            uint16_t(regionCount) * regionSize() >
+        aLength) {
+      return false;
+    }
+    return true;
+  }
+};
+
+struct DeltaSet {
+  // (int16 and int8)
+  // *or*
+  // (int32 and int16) deltaData[regionIndexCount];
+};
+
+struct DeltaSetIndexMap {
+  enum { INNER_INDEX_BIT_COUNT_MASK = 0x0f, MAP_ENTRY_SIZE_MASK = 0x30 };
+  uint8_t format;
+  uint8_t entryFormat;
+  union {
+    struct {
+      uint16 mapCount;
+      // uint8 mapData[variable];
+    } v0;
+    struct {
+      uint32 mapCount;
+      // uint8 mapData[variable];
+    } v1;
+  };
+  uint32_t entrySize() const {
+    return (((entryFormat & MAP_ENTRY_SIZE_MASK) >> 4) + 1);
+  }
+  uint32_t map(uint32_t aIndex) const {
+    uint32_t mapCount;
+    const uint8_t* mapData;
+    switch (format) {
+      case 0:
+        mapCount = uint32_t(v0.mapCount);
+        mapData = reinterpret_cast<const uint8_t*>(&v0.mapCount) +
+                  sizeof(v0.mapCount);
+        break;
+      case 1:
+        mapCount = uint32_t(v1.mapCount);
+        mapData = reinterpret_cast<const uint8_t*>(&v1.mapCount) +
+                  sizeof(v1.mapCount);
+        break;
+      default:
+        // unknown DeltaSetIndexMap format
+        return aIndex;
+    }
+    if (!mapCount) {
+      return aIndex;
+    }
+    if (aIndex >= mapCount) {
+      aIndex = mapCount - 1;
+    }
+    const uint8_t* entryData = mapData + aIndex * entrySize();
+    uint32_t entry = 0;
+    for (uint32_t i = 0; i < entrySize(); ++i) {
+      entry = (entry << 8) + entryData[i];
+    }
+    uint16_t outerIndex =
+        entry >> ((entryFormat & INNER_INDEX_BIT_COUNT_MASK) + 1);
+    uint16_t innerIndex =
+        entry & ((1 << ((entryFormat & INNER_INDEX_BIT_COUNT_MASK) + 1)) - 1);
+    return (uint32_t(outerIndex) << 16) + innerIndex;
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+enum EntryFormatMasks {
+  INNER_INDEX_BIT_COUNT_MASK = 0x0f,
+  MAP_ENTRY_SIZE_MASK = 0x30
+};
+
+struct ItemVariationData {
+  enum { WORD_DELTA_COUNT_MASK = 0x7FFF, LONG_WORDS = 0x8000 };
+  uint16 itemCount;
+  uint16 wordDeltaCount;
+  uint16 regionIndexCount;
+  // uint16 regionIndexes[regionIndexCount];
+  const uint16* regionIndexes() const {
+    return reinterpret_cast<const uint16*>(
+        reinterpret_cast<const char*>(this + 1));
+  }
+  // DeltaSet deltaSets[itemCount];
+  const DeltaSet* deltaSets() const {
+    return reinterpret_cast<const DeltaSet*>(
+        reinterpret_cast<const char*>(this + 1) +
+        uint16_t(regionIndexCount) * sizeof(uint16));
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+struct ItemVariationStore {
+  uint16 format;
+  Offset32 variationRegionListOffset;
+  uint16 itemVariationDataCount;
+  // Offset32 itemVariationDataOffsets[itemVariationDataCount];
+  const Offset32* itemVariationDataOffsets() const {
+    return reinterpret_cast<const Offset32*>(
+        reinterpret_cast<const char*>(this + 1));
+  }
+  const VariationRegionList* variationRegionList() const {
+    return reinterpret_cast<const VariationRegionList*>(
+        reinterpret_cast<const char*>(this) + variationRegionListOffset);
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+static int32_t ApplyVariation(const PaintState& aState, int32_t aValue,
+                              uint32_t aIndex) {
+  if (aIndex == 0xffffffff) {
+    return aValue;
+  }
+  const auto* store = aState.mHeader.v1->itemVariationStore();
+  if (!store || uint16_t(store->format) != 1) {
+    return aValue;
+  }
+  const DeltaSetIndexMap* map = aState.mHeader.v1->varIndexMap();
+  uint32_t mappedIndex = map ? map->map(aIndex) : aIndex;
+  uint16_t outerIndex = mappedIndex >> 16;
+  uint16_t innerIndex = mappedIndex & 0xffff;
+  const auto* itemVariationDataOffsets = store->itemVariationDataOffsets();
+  if (mappedIndex == 0xffffffff ||
+      outerIndex >= uint16_t(store->itemVariationDataCount) ||
+      !itemVariationDataOffsets[outerIndex]) {
+    return aValue;
+  }
+  const auto* regionList = store->variationRegionList();
+  if (outerIndex >= uint16_t(store->itemVariationDataCount)) {
+    return aValue;
+  }
+  const auto* variationData = reinterpret_cast<const ItemVariationData*>(
+      reinterpret_cast<const char*>(store) +
+      itemVariationDataOffsets[outerIndex]);
+  if (innerIndex >= uint16_t(variationData->itemCount)) {
+    return aValue;
+  }
+  const auto* regionIndexes = variationData->regionIndexes();
+  uint16_t regionIndexCount = variationData->regionIndexCount;
+  const DeltaSet* deltaSets = variationData->deltaSets();
+  uint16_t wordDeltaCount = variationData->wordDeltaCount;
+  bool longWords = wordDeltaCount & ItemVariationData::LONG_WORDS;
+  wordDeltaCount &= ItemVariationData::WORD_DELTA_COUNT_MASK;
+  uint32_t deltaSetSize = (regionIndexCount + wordDeltaCount) << longWords;
+  const uint8_t* deltaData =
+      reinterpret_cast<const uint8_t*>(deltaSets) + deltaSetSize * innerIndex;
+  uint16_t deltaSize = longWords ? 4 : 2;
+  int32_t result = aValue;
+  for (uint16_t i = 0; i < regionIndexCount; ++i, deltaData += deltaSize) {
+    if (i == wordDeltaCount) {
+      deltaSize >>= 1;
+    }
+    const auto* region = regionList->getRegion(uint16_t(regionIndexes[i]));
+    if (!region) {
+      return aValue;
+    }
+    // XXX Should we do the calculations here in fixed-point? Check spec.
+    float scalar = -1.0;
+    for (uint16_t axisIndex = 0; axisIndex < uint16_t(regionList->axisCount);
+         ++axisIndex) {
+      const auto& axis = region->regionAxes()[axisIndex];
+      float peak = axis.peakCoord;
+      if (peak == 0.0) {
+        // This axis cannot contribute to scalar.
+        continue;
+      }
+      float start = axis.startCoord;
+      float end = axis.endCoord;
+      float value = axisIndex < aState.mCoordCount
+                        ? float(aState.mCoords[axisIndex]) / 16384.0f
+                        : 0.0;
+      if (value < start || value > end) {
+        // Out of range: this region is not applicable.
+        scalar = -1.0;
+        break;
+      }
+      if (scalar < 0.0) {
+        scalar = 1.0;
+      }
+      if (value == peak) {
+        continue;
+      }
+      if (value < peak && peak > start) {
+        scalar *= (value - start) / (peak - start);
+      } else if (value > peak && peak < end) {
+        scalar *= (end - value) / (end - peak);
+      }
+    }
+    if (scalar <= 0.0) {
+      continue;
+    }
+    int32_t delta = *reinterpret_cast<const int8_t*>(deltaData);  // sign-extend
+    for (uint16_t j = 1; j < deltaSize; ++j) {
+      delta = (delta << 8) | deltaData[j];
+    }
+    delta = int32_t(floorf((float(delta) * scalar) + 0.5f));
+    result += delta;
+  }
+  return result;
+};
+
+static float ApplyVariation(const PaintState& aState, Fixed aValue,
+                            uint32_t aIndex) {
+  return float(ApplyVariation(aState, aValue.intRepr(), aIndex)) /
+         (1 << Fixed::kFractionBits);
+}
+
+static float ApplyVariation(const PaintState& aState, F2DOT14 aValue,
+                            uint32_t aIndex) {
+  return float(ApplyVariation(aState, aValue.intRepr(), aIndex)) /
+         (1 << F2DOT14::kFractionBits);
+}
+
+struct ClipBoxFormat1 {
+  enum { kFormat = 1 };
+  uint8_t format;
+  FWORD xMin;
+  FWORD yMin;
+  FWORD xMax;
+  FWORD yMax;
+
+  Rect GetRect(const PaintState& aState) const {
+    MOZ_ASSERT(format == kFormat);
+    int32_t x0 = int16_t(xMin);
+    int32_t y0 = int16_t(yMin);
+    int32_t x1 = int16_t(xMax);
+    int32_t y1 = int16_t(yMax);
+    // Flip the y-coordinates to map from OpenType to Moz2d space.
+    return Rect(aState.F2P(x0), -aState.F2P(y1), aState.F2P(x1 - x0),
+                aState.F2P(y1 - y0));
+  }
+};
+
+struct ClipBoxFormat2 : public ClipBoxFormat1 {
+  enum { kFormat = 2 };
+  uint32 varIndexBase;
+
+  Rect GetRect(const PaintState& aState) const {
+    MOZ_ASSERT(format == kFormat);
+    int32_t x0 = ApplyVariation(aState, int16_t(xMin), varIndexBase);
+    int32_t y0 = ApplyVariation(aState, int16_t(yMin), SatAdd(varIndexBase, 1));
+    int32_t x1 = ApplyVariation(aState, int16_t(xMax), SatAdd(varIndexBase, 2));
+    int32_t y1 = ApplyVariation(aState, int16_t(yMax), SatAdd(varIndexBase, 3));
+    return Rect(aState.F2P(x0), -aState.F2P(y1), aState.F2P(x1 - x0),
+                aState.F2P(y1 - y0));
+  }
+};
+
+struct Clip {
+  uint16 startGlyphID;
+  uint16 endGlyphID;
+  Offset24 clipBoxOffset;
+
+  Rect GetRect(const PaintState& aState) const {
+    uint32_t offset = aState.mHeader.v1->clipListOffset + clipBoxOffset;
+    const auto* box = aState.COLRv1BaseAddr() + offset;
+    switch (*box) {
+      case 1:
+        return reinterpret_cast<const ClipBoxFormat1*>(box)->GetRect(aState);
+      case 2:
+        return reinterpret_cast<const ClipBoxFormat2*>(box)->GetRect(aState);
+      default:
+        // unknown ClipBoxFormat
+        break;
+    }
+    return Rect();
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+struct ClipList {
+  uint8_t format;
+  uint32 numClips;
+  // Clip clips[numClips]
+  const Clip* clips() const { return reinterpret_cast<const Clip*>(this + 1); }
+  const Clip* GetClip(uint32_t aGlyphId) const {
+    auto compare = [](const void* key, const void* data) -> int {
+      uint32_t glyphId = (uint32_t)(uintptr_t)key;
+      const auto* clip = reinterpret_cast<const Clip*>(data);
+      uint32_t start = uint16_t(clip->startGlyphID);
+      uint32_t end = uint16_t(clip->endGlyphID);
+      if (start <= glyphId && end >= glyphId) {
+        return 0;
+      }
+      return start > glyphId ? -1 : 1;
+    };
+    return reinterpret_cast<const Clip*>(bsearch((void*)(uintptr_t)aGlyphId,
+                                                 clips(), uint32_t(numClips),
+                                                 sizeof(Clip), compare));
+  }
+  bool Validate(const COLRv1Header* aHeader, uint64_t aLength) const;
+};
+
+struct LayerRecord {
+  uint16 glyphId;
+  uint16 paletteEntryIndex;
+
+  bool Paint(const PaintState& aState, float aAlpha,
+             const Point& aPoint) const {
+    Glyph glyph{uint16_t(glyphId), aPoint};
+    GlyphBuffer buffer{&glyph, 1};
+    aState.mDrawTarget->FillGlyphs(
+        aState.mScaledFont, buffer,
+        ColorPattern(aState.GetColor(paletteEntryIndex, aAlpha)),
+        aState.mDrawOptions);
+    return true;
+  }
+};
+
+struct BaseGlyphRecord {
+  uint16 glyphId;
+  uint16 firstLayerIndex;
+  uint16 numLayers;
+
+  bool Paint(const PaintState& aState, float aAlpha,
+             const Point& aPoint) const {
+    uint32_t layerIndex = uint16_t(firstLayerIndex);
+    uint32_t end = layerIndex + uint16_t(numLayers);
+    if (end > uint16_t(aState.mHeader.v0->numLayerRecords)) {
+      MOZ_ASSERT_UNREACHABLE("bad COLRv0 table");
+      return false;
+    }
+    const auto* layers = aState.mHeader.v0->GetLayerRecords();
+    while (layerIndex < end) {
+      if (!layers[layerIndex].Paint(aState, aAlpha, aPoint)) {
+        return false;
+      }
+      ++layerIndex;
+    }
+    return true;
+  }
+};
+
+struct ColorStop {
+  F2DOT14 stopOffset;
+  uint16 paletteIndex;
+  F2DOT14 alpha;
+
+  float GetStopOffset(const PaintState& aState) const { return stopOffset; }
+  uint16_t GetPaletteIndex() const { return paletteIndex; }
+  float GetAlpha(const PaintState& aState) const { return alpha; }
+};
+
+struct VarColorStop : public ColorStop {
+  uint32 varIndexBase;
+
+  float GetStopOffset(const PaintState& aState) const {
+    return ApplyVariation(aState, stopOffset, varIndexBase);
+  }
+  float GetAlpha(const PaintState& aState) const {
+    return ApplyVariation(aState, alpha, SatAdd(varIndexBase, 1));
+  }
+};
+
+template <typename T>
+struct ColorLineT {
+  enum { EXTEND_PAD = 0, EXTEND_REPEAT = 1, EXTEND_REFLECT = 2 };
+  uint8_t extend;
+  uint16 numStops;
+  const T* colorStops() const { return reinterpret_cast<const T*>(this + 1); }
+
+  // If the color line has only one stop, return it as a simple ColorPattern.
+  UniquePtr<Pattern> AsSolidColor(const PaintState& aState) const {
+    if (uint16_t(numStops) != 1) {
+      return nullptr;
+    }
+    const auto* stop = colorStops();
+    return MakeUnique<ColorPattern>(
+        aState.GetColor(stop->GetPaletteIndex(), stop->GetAlpha(aState)));
+  }
+
+  // Retrieve the color stops into an array of GradientStop records. The stops
+  // are normalized to the range [0 .. 1], and the original offsets of the
+  // first and last stops are returned.
+  // If aReverse is true, the color line is reversed.
+  void CollectGradientStops(const PaintState& aState,
+                            nsTArray<GradientStop>& aStops, float* aFirstStop,
+                            float* aLastStop, bool aReverse = false) const {
+    MOZ_ASSERT(aStops.IsEmpty());
+    uint16_t count = numStops;
+    if (!count) {
+      return;
+    }
+    const auto* stop = colorStops();
+    if (reinterpret_cast<const char*>(stop) + count * sizeof(T) >
+        aState.COLRv1BaseAddr() + aState.mCOLRLength) {
+      return;
+    }
+    aStops.SetCapacity(count);
+    for (uint16_t i = 0; i < count; ++i, ++stop) {
+      DeviceColor color =
+          aState.GetColor(stop->GetPaletteIndex(), stop->GetAlpha(aState));
+      aStops.AppendElement(GradientStop{stop->GetStopOffset(aState), color});
+    }
+    if (count == 1) {
+      *aFirstStop = *aLastStop = aStops[0].offset;
+      return;
+    }
+    aStops.StableSort(nsDefaultComparator<GradientStop, GradientStop>());
+    if (aReverse) {
+      float a = aStops[0].offset;
+      float b = aStops.LastElement().offset;
+      aStops.Reverse();
+      for (auto& gs : aStops) {
+        gs.offset = a + b - gs.offset;
+      }
+    }
+    // Normalize stops to the range 0.0 .. 1.0, and return the original
+    // start & end.
+    // Note that if all stops are at the same offset, no normalization
+    // will be done.
+    *aFirstStop = aStops[0].offset;
+    *aLastStop = aStops.LastElement().offset;
+    if ((*aLastStop > *aFirstStop) &&
+        (*aLastStop != 1.0f || *aFirstStop != 0.0f)) {
+      float f = 1.0f / (*aLastStop - *aFirstStop);
+      for (auto& gs : aStops) {
+        gs.offset = (gs.offset - *aFirstStop) * f;
+      }
+    }
+  }
+
+  // Create a gfx::GradientStops representing the given color line stops,
+  // applying our extend mode.
+  already_AddRefed<GradientStops> MakeGradientStops(
+      const PaintState& aState, nsTArray<GradientStop>& aStops) const {
+    auto mapExtendMode = [](uint8_t aExtend) -> ExtendMode {
+      switch (aExtend) {
+        case EXTEND_REPEAT:
+          return ExtendMode::REPEAT;
+        case EXTEND_REFLECT:
+          return ExtendMode::REFLECT;
+        case EXTEND_PAD:
+        default:
+          return ExtendMode::CLAMP;
+      }
+    };
+    return aState.mDrawTarget->CreateGradientStops(
+        aStops.Elements(), aStops.Length(), mapExtendMode(extend));
+  }
+
+  already_AddRefed<GradientStops> MakeGradientStops(
+      const PaintState& aState, float* aFirstStop, float* aLastStop,
+      bool aReverse = false) const {
+    AutoTArray<GradientStop, 8> stops;
+    CollectGradientStops(aState, stops, aFirstStop, aLastStop, aReverse);
+    if (stops.IsEmpty()) {
+      return nullptr;
+    }
+    return MakeGradientStops(aState, stops);
+  }
+};
+
+using ColorLine = ColorLineT<ColorStop>;
+using VarColorLine = ColorLineT<VarColorStop>;
+
+// Used to check for cycles in the paint graph, and bail out to avoid infinite
+// recursion when traversing the graph in Paint() or GetBoundingRect(). (Only
+// PaintColrLayers and PaintColrGlyph can cause cycles; all other paint types
+// have only forward references within the table.)
+#define IF_CYCLE_RETURN(retval)             \
+  if (aState.mVisited->Contains(aOffset)) { \
+    return retval;                          \
+  }                                         \
+  aState.mVisited->AppendElement(aOffset);  \
+  ScopeExit e([aState]() { aState.mVisited->RemoveLastElement(); })
+
+struct PaintColrLayers {
+  enum { kFormat = 1 };
+  uint8_t format;
+  uint8_t numLayers;
+  uint32 firstLayerIndex;
+
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    MOZ_ASSERT(format == kFormat);
+    IF_CYCLE_RETURN(true);
+    const auto* layerList = aState.mHeader.v1->layerList();
+    if (!layerList) {
+      return false;
+    }
+    if (uint64_t(firstLayerIndex) + numLayers > layerList->numLayers) {
+      return false;
+    }
+    const auto* paintOffsets = layerList->paintOffsets() + firstLayerIndex;
+    for (uint32_t i = 0; i < numLayers; i++) {
+      if (!DispatchPaint(aState,
+                         aState.mHeader.v1->layerListOffset + paintOffsets[i],
+                         aBounds)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    IF_CYCLE_RETURN(Rect());
+    const auto* layerList = aState.mHeader.v1->layerList();
+    if (!layerList) {
+      return Rect();
+    }
+    if (uint64_t(firstLayerIndex) + numLayers > layerList->numLayers) {
+      return Rect();
+    }
+    Rect result;
+    const auto* paintOffsets = layerList->paintOffsets() + firstLayerIndex;
+    for (uint32_t i = 0; i < numLayers; i++) {
+      result = result.Union(DispatchGetBounds(
+          aState, aState.mHeader.v1->layerListOffset + paintOffsets[i]));
+    }
+    return result;
+  }
+};
+
+struct PaintPatternBase {
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    Matrix m = aState.mDrawTarget->GetTransform();
+    if (m.Invert()) {
+      if (auto pattern = DispatchMakePattern(aState, aOffset)) {
+        aState.mDrawTarget->FillRect(
+            m.TransformBounds(IntRectToRect(aState.mDrawTarget->GetRect())),
+            *pattern, aState.mDrawOptions);
+        return true;
+      }
+    }
+    return false;
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    return Rect();
+  }
+};
+
+struct PaintSolid : public PaintPatternBase {
+  enum { kFormat = 2 };
+  uint8_t format;
+  uint16 paletteIndex;
+  F2DOT14 alpha;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return MakeUnique<ColorPattern>(aState.GetColor(paletteIndex, alpha));
+  }
+};
+
+struct PaintVarSolid : public PaintSolid {
+  enum { kFormat = 3 };
+  uint32 varIndexBase;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return MakeUnique<ColorPattern>(aState.GetColor(
+        paletteIndex, ApplyVariation(aState, alpha, varIndexBase)));
+  }
+};
+
+struct PaintLinearGradient : public PaintPatternBase {
+  enum { kFormat = 4 };
+  uint8_t format;
+  Offset24 colorLineOffset;
+  FWORD x0;
+  FWORD y0;
+  FWORD x1;
+  FWORD y1;
+  FWORD x2;
+  FWORD y2;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(ColorLine) + sizeof(ColorStop) > aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine =
+        reinterpret_cast<const ColorLine*>(aState.COLRv1BaseAddr() + clOffset);
+    Point p0(aState.F2P(int16_t(x0)), aState.F2P(int16_t(y0)));
+    Point p1(aState.F2P(int16_t(x1)), aState.F2P(int16_t(y1)));
+    Point p2(aState.F2P(int16_t(x2)), aState.F2P(int16_t(y2)));
+    return NormalizeAndMakeGradient(aState, colorLine, p0, p1, p2);
+  }
+
+  template <typename T>
+  UniquePtr<Pattern> NormalizeAndMakeGradient(const PaintState& aState,
+                                              const T* aColorLine, Point p0,
+                                              Point p1, Point p2) const {
+    // Ill-formed gradient should not be rendered.
+    if (p1 == p0 || p2 == p0) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    UniquePtr<Pattern> solidColor = aColorLine->AsSolidColor(aState);
+    if (solidColor) {
+      return solidColor;
+    }
+    float firstStop, lastStop;
+    AutoTArray<GradientStop, 8> stopArray;
+    aColorLine->CollectGradientStops(aState, stopArray, &firstStop, &lastStop);
+    if (stopArray.IsEmpty()) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    if (firstStop != 0.0 || lastStop != 1.0) {
+      if (firstStop == lastStop) {
+        if (aColorLine->extend != T::EXTEND_PAD) {
+          return MakeUnique<ColorPattern>(DeviceColor());
+        }
+        // For extend-pad, when the color line is zero-length, we add a "fake"
+        // color stop to create a [0.0..1.0]-normalized color line, so that the
+        // projection of points below works as expected.
+        for (auto& gs : stopArray) {
+          gs.offset = 0.0f;
+        }
+        stopArray.AppendElement(
+            GradientStop{1.0f, stopArray.LastElement().color});
+        lastStop += 1.0f;
+      }
+      // Adjust positions of the points to account for normalization of the
+      // color line stop offsets.
+      Point v = p1 - p0;
+      p0 += v * firstStop;
+      p1 -= v * (1.0f - lastStop);
+      // Move the rotation vector to maintain the same direction from p0.
+      p2 += v * firstStop;
+    }
+    Point p3;
+    if (FuzzyEqualsMultiplicative(p2.y, p0.y)) {
+      // rotation vector is horizontal
+      p3 = Point(p0.x, p1.y);
+    } else if (FuzzyEqualsMultiplicative(p2.x, p0.x)) {
+      // rotation vector is vertical
+      p3 = Point(p1.x, p0.y);
+    } else {
+      float m = (p2.y - p0.y) / (p2.x - p0.x);  // slope of line p0->p2
+      float mInv = -1.0f / m;         // slope of desired perpendicular p0->p3
+      float c1 = p0.y - mInv * p0.x;  // line p0->p3 is m * x - y + c1 = 0
+      float c2 = p1.y - m * p1.x;     // line p1->p3 is mInv * x - y + c2 = 0
+      float x3 = (c1 - c2) / (m - mInv);
+      float y3 = (c1 * m - c2 * mInv) / (m - mInv);
+      p3 = Point(x3, y3);
+    }
+    RefPtr stops = aColorLine->MakeGradientStops(aState, stopArray);
+    return MakeUnique<LinearGradientPattern>(p0, p3, std::move(stops),
+                                             Matrix::Scaling(1.0, -1.0));
+  }
+};
+
+struct PaintVarLinearGradient : public PaintLinearGradient {
+  enum { kFormat = 5 };
+  uint32 varIndexBase;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(VarColorLine) + sizeof(VarColorStop) >
+        aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine = reinterpret_cast<const VarColorLine*>(
+        aState.COLRv1BaseAddr() + clOffset);
+    Point p0(aState.F2P(ApplyVariation(aState, int16_t(x0), varIndexBase)),
+             aState.F2P(
+                 ApplyVariation(aState, int16_t(y0), SatAdd(varIndexBase, 1))));
+    Point p1(aState.F2P(
+                 ApplyVariation(aState, int16_t(x1), SatAdd(varIndexBase, 2))),
+             aState.F2P(
+                 ApplyVariation(aState, int16_t(y1), SatAdd(varIndexBase, 3))));
+    Point p2(aState.F2P(
+                 ApplyVariation(aState, int16_t(x2), SatAdd(varIndexBase, 4))),
+             aState.F2P(
+                 ApplyVariation(aState, int16_t(y2), SatAdd(varIndexBase, 5))));
+    return NormalizeAndMakeGradient(aState, colorLine, p0, p1, p2);
+  }
+};
+
+struct PaintRadialGradient : public PaintPatternBase {
+  enum { kFormat = 6 };
+  uint8_t format;
+  Offset24 colorLineOffset;
+  FWORD x0;
+  FWORD y0;
+  UFWORD radius0;
+  FWORD x1;
+  FWORD y1;
+  UFWORD radius1;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(ColorLine) + sizeof(ColorStop) > aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine =
+        reinterpret_cast<const ColorLine*>(aState.COLRv1BaseAddr() + clOffset);
+    Point c1(aState.F2P(int16_t(x0)), aState.F2P(int16_t(y0)));
+    Point c2(aState.F2P(int16_t(x1)), aState.F2P(int16_t(y1)));
+    float r1 = aState.F2P(uint16_t(radius0));
+    float r2 = aState.F2P(uint16_t(radius1));
+    return NormalizeAndMakeGradient(aState, colorLine, c1, c2, r1, r2);
+  }
+
+  // Helper function to trim the gradient stops array at the start or end.
+  void TruncateGradientStops(nsTArray<GradientStop>& aStops, float aStart,
+                             float aEnd) const {
+    // For pad mode, we may need a sub-range of the line: figure out which
+    // stops to trim, and interpolate as needed at truncation point(s).
+    // (Currently this is only ever used to trim one end of the color line,
+    // so edge cases that may occur when trimming both ends are untested.)
+    MOZ_ASSERT(aStart == 0.0f || aEnd == 1.0f,
+               "Trimming both ends of color-line is untested!");
+
+    // Create a color that is |r| of the way from c1 to c2.
+    auto interpolateColor = [](DeviceColor c1, DeviceColor c2, float r) {
+      return DeviceColor(
+          c2.r * r + c1.r * (1.0f - r), c2.g * r + c1.g * (1.0f - r),
+          c2.b * r + c1.b * (1.0f - r), c2.a * r + c1.a * (1.0f - r));
+    };
+
+    size_t count = aStops.Length();
+    MOZ_ASSERT(count > 1);
+
+    // Truncate at the start of the color line?
+    if (aStart > 0.0f) {
+      // Skip forward past any stops that can be dropped.
+      size_t i = 0;
+      while (i < count - 1 && aStops[i].offset < aStart) {
+        ++i;
+      }
+      // If we're not truncating exactly at a color-stop offset, shift the
+      // preceding stop to the truncation offset and interpolate its color.
+      if (i && aStops[i].offset > aStart) {
+        auto& prev = aStops[i - 1];
+        auto& curr = aStops[i];
+        float ratio = (aStart - prev.offset) / (curr.offset - prev.offset);
+        prev.color = interpolateColor(prev.color, curr.color, ratio);
+        prev.offset = aStart;
+        --i;  // We don't want to remove this stop, as we adjusted it.
+      }
+      aStops.RemoveElementsAt(0, i);
+      // Re-normalize the remaining stops to the [0, 1] range.
+      if (aStart < 1.0f) {
+        float r = 1.0f / (1.0f - aStart);
+        for (auto& gs : aStops) {
+          gs.offset = r * (gs.offset - aStart);
+        }
+      }
+    }
+
+    // Truncate at the end of the color line?
+    if (aEnd < 1.0f) {
+      // Skip back over any stops that can be dropped.
+      size_t i = count - 1;
+      while (i && aStops[i].offset > aEnd) {
+        --i;
+      }
+      // If we're not truncating exactly at a color-stop offset, shift the
+      // following stop to the truncation offset and interpolate its color.
+      if (i + 1 < count && aStops[i].offset < aEnd) {
+        auto& next = aStops[i + 1];
+        auto& curr = aStops[i];
+        float ratio = (aEnd - curr.offset) / (next.offset - curr.offset);
+        next.color = interpolateColor(curr.color, next.color, ratio);
+        next.offset = aEnd;
+        ++i;
+      }
+      aStops.RemoveElementsAt(i + 1, count - i - 1);
+      // Re-normalize the remaining stops to the [0, 1] range.
+      if (aEnd > 0.0f) {
+        float r = 1.0f / aEnd;
+        for (auto& gs : aStops) {
+          gs.offset = r * gs.offset;
+        }
+      }
+    }
+  }
+
+  template <typename T>
+  UniquePtr<Pattern> NormalizeAndMakeGradient(const PaintState& aState,
+                                              const T* aColorLine, Point c1,
+                                              Point c2, float r1,
+                                              float r2) const {
+    if ((c1 == c2 && r1 == r2) || (r1 == 0.0 && r2 == 0.0)) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    UniquePtr<Pattern> solidColor = aColorLine->AsSolidColor(aState);
+    if (solidColor) {
+      return solidColor;
+    }
+    float firstStop, lastStop;
+    AutoTArray<GradientStop, 8> stopArray;
+    aColorLine->CollectGradientStops(aState, stopArray, &firstStop, &lastStop);
+    if (stopArray.IsEmpty()) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    // If the color stop offsets had to be normalized to the [0, 1] range,
+    // adjust the circle positions and radii to match.
+    if (firstStop != 0.0f || lastStop != 1.0f) {
+      if (firstStop == lastStop) {
+        if (aColorLine->extend != T::EXTEND_PAD) {
+          return MakeUnique<ColorPattern>(DeviceColor());
+        }
+        // For extend-pad, when the color line is zero-length, we add a "fake"
+        // color stop to ensure we'll maintain the orientation of the cone,
+        // otherwise when we adjust circles to account for the normalized color
+        // stops, the centers will coalesce and the cone or cylinder collapses.
+        for (auto& gs : stopArray) {
+          gs.offset = 0.0f;
+        }
+        stopArray.AppendElement(
+            GradientStop{1.0f, stopArray.LastElement().color});
+        lastStop += 1.0f;
+      }
+      // Adjust centers along the vector between them, and scale radii for
+      // gradient line defined from 0.0 to 1.0.
+      Point vec = c2 - c1;
+      c1 += vec * firstStop;
+      c2 -= vec * (1.0f - lastStop);
+      float deltaR = r2 - r1;
+      r1 = r1 + deltaR * firstStop;
+      r2 = r2 - deltaR * (1.0f - lastStop);
+    }
+    if ((r1 < 0.0f || r2 < 0.0f) && aColorLine->extend == T::EXTEND_PAD) {
+      // For EXTEND_PAD, we can restrict the gradient definition to just its
+      // visible portion because the shader doesn't need to see any part of the
+      // color line that extends into the negative-radius "virtual cone".
+      if (r1 < 0.0f && r2 < 0.0f) {
+        // If both radii are negative, then only the color at the closer circle
+        // will appear in the projected positive cone (or if they're equal,
+        // nothing will be visible at all).
+        if (r1 == r2) {
+          return MakeUnique<ColorPattern>(DeviceColor());
+        }
+        // The defined range of the color line is entirely in the invisible
+        // cone; all that will project into visible space is a single color.
+        if (r1 < r2) {
+          // Keep only the last color stop.
+          stopArray.RemoveElementsAt(0, stopArray.Length() - 1);
+        } else {
+          // Keep only the first color stop.
+          stopArray.RemoveElementsAt(1, stopArray.Length() - 1);
+        }
+      } else {
+        // Truncate the gradient at the tip of the visible cone: find the color
+        // stops closest to that point and interpolate between them.
+        if (r1 < r2) {
+          float start = r1 / (r1 - r2);
+          TruncateGradientStops(stopArray, start, 1.0f);
+          r1 = 0.0f;
+          c1 = c1 * (1.0f - start) + c2 * start;
+        } else if (r2 < r1) {
+          float end = 1.0f - r2 / (r2 - r1);
+          TruncateGradientStops(stopArray, 0.0f, end);
+          r2 = 0.0f;
+          c2 = c1 * (1.0f - end) + c2 * end;
+        }
+      }
+    }
+    // Handle negative radii, which the shader won't understand directly, by
+    // projecting the circles along the cones such that both radii are positive.
+    if (r1 < 0.0f || r2 < 0.0f) {
+      float deltaR = r2 - r1;
+      // If deltaR is zero, then nothing is visible because the cone has
+      // degenerated into a negative-radius cylinder, and does not project
+      // into visible space at all.
+      if (deltaR == 0.0f) {
+        return MakeUnique<ColorPattern>(DeviceColor());
+      }
+      Point vec = c2 - c1;
+      if (aColorLine->extend == T::EXTEND_REFLECT) {
+        deltaR *= 2.0f;
+        vec = vec * 2.0f;
+      }
+      if (r2 < r1) {
+        vec = -vec;
+        deltaR = -deltaR;
+      }
+      // Number of repeats by which we need to shift.
+      float n = std::ceil(std::max(-r1, -r2) / deltaR);
+      deltaR *= n;
+      r1 += deltaR;
+      r2 += deltaR;
+      vec = vec * n;
+      c1 += vec;
+      c2 += vec;
+    }
+    RefPtr stops = aColorLine->MakeGradientStops(aState, stopArray);
+    if (!stops) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    return MakeUnique<RadialGradientPattern>(c1, c2, r1, r2, std::move(stops),
+                                             Matrix::Scaling(1.0, -1.0));
+  }
+};
+
+struct PaintVarRadialGradient : public PaintRadialGradient {
+  enum { kFormat = 7 };
+  uint32 varIndexBase;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(VarColorLine) + sizeof(VarColorStop) >
+        aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine = reinterpret_cast<const VarColorLine*>(
+        aState.COLRv1BaseAddr() + clOffset);
+    Point c1(aState.F2P(ApplyVariation(aState, int16_t(x0), varIndexBase)),
+             aState.F2P(
+                 ApplyVariation(aState, int16_t(y0), SatAdd(varIndexBase, 1))));
+    float r1 = aState.F2P(
+        ApplyVariation(aState, uint16_t(radius0), SatAdd(varIndexBase, 2)));
+    Point c2(aState.F2P(
+                 ApplyVariation(aState, int16_t(x1), SatAdd(varIndexBase, 3))),
+             aState.F2P(
+                 ApplyVariation(aState, int16_t(y1), SatAdd(varIndexBase, 4))));
+    float r2 = aState.F2P(
+        ApplyVariation(aState, uint16_t(radius1), SatAdd(varIndexBase, 5)));
+    return NormalizeAndMakeGradient(aState, colorLine, c1, c2, r1, r2);
+  }
+};
+
+struct PaintSweepGradient : public PaintPatternBase {
+  enum { kFormat = 8 };
+  uint8_t format;
+  Offset24 colorLineOffset;
+  FWORD centerX;
+  FWORD centerY;
+  F2DOT14 startAngle;
+  F2DOT14 endAngle;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(ColorLine) + sizeof(ColorStop) > aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine =
+        reinterpret_cast<const ColorLine*>(aState.COLRv1BaseAddr() + clOffset);
+    float start = float(startAngle) + 1.0f;
+    float end = float(endAngle) + 1.0f;
+    Point center(aState.F2P(int16_t(centerX)), aState.F2P(int16_t(centerY)));
+    return NormalizeAndMakeGradient(aState, colorLine, center, start, end);
+  }
+
+  template <typename T>
+  UniquePtr<Pattern> NormalizeAndMakeGradient(const PaintState& aState,
+                                              const T* aColorLine,
+                                              Point aCenter, float aStart,
+                                              float aEnd) const {
+    if (aStart == aEnd && aColorLine->extend != T::EXTEND_PAD) {
+      return MakeUnique<ColorPattern>(DeviceColor());
+    }
+    UniquePtr<Pattern> solidColor = aColorLine->AsSolidColor(aState);
+    if (solidColor) {
+      return solidColor;
+    }
+    // ConicGradientPattern works counterclockwise. If the gradient is defined
+    // clockwise (with aStart greater than aEnd), we'll reverse the color line
+    // and swap the start and end angles.
+    bool reverse = aEnd < aStart;
+    float firstStop, lastStop;
+    RefPtr stops =
+        aColorLine->MakeGradientStops(aState, &firstStop, &lastStop, reverse);
+    if (!stops) {
+      return nullptr;
+    }
+    if (firstStop != 0.0 || lastStop != 1.0) {
+      if (firstStop == lastStop) {
+        if (aColorLine->extend != T::EXTEND_PAD) {
+          return MakeUnique<ColorPattern>(DeviceColor());
+        }
+      } else {
+        float sweep = aEnd - aStart;
+        aStart = aStart + sweep * firstStop;
+        aEnd = aStart + sweep * (lastStop - firstStop);
+      }
+    }
+    if (reverse) {
+      std::swap(aStart, aEnd);
+    }
+    return MakeUnique<ConicGradientPattern>(aCenter, M_PI / 2.0, aStart / 2.0,
+                                            aEnd / 2.0, std::move(stops),
+                                            Matrix::Scaling(1.0, -1.0));
+  }
+};
+
+struct PaintVarSweepGradient : public PaintSweepGradient {
+  enum { kFormat = 9 };
+  uint32 varIndexBase;
+
+  UniquePtr<Pattern> MakePattern(const PaintState& aState,
+                                 uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    uint32_t clOffset = aOffset + colorLineOffset;
+    if (clOffset + sizeof(VarColorLine) + sizeof(VarColorStop) >
+        aState.mCOLRLength) {
+      return nullptr;
+    }
+    const auto* colorLine = reinterpret_cast<const VarColorLine*>(
+        aState.COLRv1BaseAddr() + clOffset);
+    float start =
+        ApplyVariation(aState, startAngle, SatAdd(varIndexBase, 2)) + 1.0f;
+    float end =
+        ApplyVariation(aState, endAngle, SatAdd(varIndexBase, 3)) + 1.0f;
+    Point center(
+        aState.F2P(ApplyVariation(aState, int16_t(centerX), varIndexBase)),
+        aState.F2P(
+            ApplyVariation(aState, int16_t(centerY), SatAdd(varIndexBase, 1))));
+    return NormalizeAndMakeGradient(aState, colorLine, center, start, end);
+  }
+};
+
+struct PaintGlyph {
+  enum { kFormat = 10 };
+  uint8_t format;
+  Offset24 paintOffset;
+  uint16 glyphID;
+
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    MOZ_ASSERT(format == kFormat);
+    if (!paintOffset) {
+      return true;
+    }
+    Glyph g{uint16_t(glyphID), Point()};
+    GlyphBuffer buffer{&g, 1};
+    // If the paint is a simple fill (rather than a sub-graph of further paint
+    // records), we can just use FillGlyphs to render it instead of setting up
+    // a clip.
+    UniquePtr<Pattern> fillPattern =
+        DispatchMakePattern(aState, aOffset + paintOffset);
+    if (fillPattern) {
+      // On macOS we can't use FillGlyphs because when we render the glyph,
+      // Core Text's own color font support may step in and ignore the
+      // pattern. So to avoid this, fill the glyph as a path instead.
+#if XP_MACOSX
+      RefPtr<Path> path =
+          aState.mScaledFont->GetPathForGlyphs(buffer, aState.mDrawTarget);
+      aState.mDrawTarget->Fill(path, *fillPattern, aState.mDrawOptions);
+#else
+      aState.mDrawTarget->FillGlyphs(aState.mScaledFont, buffer, *fillPattern,
+                                     aState.mDrawOptions);
+#endif
+      return true;
+    }
+    RefPtr<Path> path =
+        aState.mScaledFont->GetPathForGlyphs(buffer, aState.mDrawTarget);
+    aState.mDrawTarget->PushClip(path);
+    bool ok = DispatchPaint(aState, aOffset + paintOffset, aBounds);
+    aState.mDrawTarget->PopClip();
+    return ok;
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Glyph g{uint16_t(glyphID), Point()};
+    GlyphBuffer buffer{&g, 1};
+    RefPtr<Path> path =
+        aState.mScaledFont->GetPathForGlyphs(buffer, aState.mDrawTarget);
+    return path->GetFastBounds();
+  }
+};
+
+struct PaintColrGlyph {
+  enum { kFormat = 11 };
+  uint8_t format;
+  uint16 glyphID;
+
+  // Factored out as a helper because this is also used by the top-level
+  // PaintGlyphGraph function.
+  static bool DoPaint(const PaintState& aState,
+                      const BaseGlyphPaintRecord* aBaseGlyphPaint,
+                      uint32_t aGlyphId, const Rect* aBounds) {
+    AutoPopClips clips(aState.mDrawTarget);
+    Rect clipRect;
+    if (const auto* clipList = aState.mHeader.v1->clipList()) {
+      if (const auto* clip = clipList->GetClip(aGlyphId)) {
+        clipRect = clip->GetRect(aState);
+        clips.PushClipRect(clipRect);
+        if (!aBounds) {
+          aBounds = &clipRect;
+        }
+      }
+    }
+    return DispatchPaint(
+        aState,
+        aState.mHeader.v1->baseGlyphListOffset + aBaseGlyphPaint->paintOffset,
+        aBounds);
+  }
+
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    MOZ_ASSERT(format == kFormat);
+    IF_CYCLE_RETURN(true);
+    const auto* base = aState.mHeader.v1->GetBaseGlyphPaint(glyphID);
+    return base ? DoPaint(aState, base, uint16_t(glyphID), aBounds) : false;
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    IF_CYCLE_RETURN(Rect());
+    if (const auto* clipList = aState.mHeader.v1->clipList()) {
+      if (const auto* clip = clipList->GetClip(uint16_t(glyphID))) {
+        return clip->GetRect(aState);
+      }
+    }
+    if (const auto* base =
+            aState.mHeader.v1->GetBaseGlyphPaint(uint16_t(glyphID))) {
+      return DispatchGetBounds(
+          aState, aState.mHeader.v1->baseGlyphListOffset + base->paintOffset);
+    }
+    return Rect();
+  }
+};
+
+#undef IF_CYCLE_RETURN
+
+struct Affine2x3 {
+  Fixed xx;
+  Fixed yx;
+  Fixed xy;
+  Fixed yy;
+  Fixed dx;
+  Fixed dy;
+
+  Matrix AsMatrix(const PaintState& aState) const {
+    // Flip signs because of opposite y-axis direction in moz2d vs opentype.
+    return Matrix(float(xx), -float(yx), -float(xy), float(yy),
+                  aState.F2P(float(dx)), -aState.F2P(float(dy)));
+  }
+};
+
+struct VarAffine2x3 : public Affine2x3 {
+  uint32 varIndexBase;
+
+  Matrix AsMatrix(const PaintState& aState) const {
+    return Matrix(
+        ApplyVariation(aState, xx, varIndexBase),
+        -ApplyVariation(aState, yx, SatAdd(varIndexBase, 1)),
+        -ApplyVariation(aState, xy, SatAdd(varIndexBase, 2)),
+        ApplyVariation(aState, yy, SatAdd(varIndexBase, 3)),
+        aState.F2P(ApplyVariation(aState, dx, SatAdd(varIndexBase, 4))),
+        -aState.F2P(ApplyVariation(aState, dy, SatAdd(varIndexBase, 5))));
+  };
+};
+
+struct PaintTransformBase {
+  uint8_t format;
+  Offset24 paintOffset;
+
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    if (!paintOffset) {
+      return true;
+    }
+    AutoRestoreTransform saveTransform(aState.mDrawTarget);
+    aState.mDrawTarget->ConcatTransform(DispatchGetMatrix(aState, aOffset));
+    return DispatchPaint(aState, aOffset + paintOffset, aBounds);
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    if (!paintOffset) {
+      return Rect();
+    }
+    Rect bounds = DispatchGetBounds(aState, aOffset + paintOffset);
+    bounds = DispatchGetMatrix(aState, aOffset).TransformBounds(bounds);
+    return bounds;
+  }
+};
+
+struct PaintTransform : public PaintTransformBase {
+  enum { kFormat = 12 };
+  Offset24 transformOffset;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    if (aOffset + transformOffset + sizeof(Affine2x3) > aState.mCOLRLength) {
+      return Matrix();
+    }
+    const auto* t = reinterpret_cast<const Affine2x3*>(
+        aState.COLRv1BaseAddr() + aOffset + transformOffset);
+    return t->AsMatrix(aState);
+  }
+};
+
+struct PaintVarTransform : public PaintTransformBase {
+  enum { kFormat = 13 };
+  Offset24 transformOffset;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    if (aOffset + transformOffset + sizeof(VarAffine2x3) > aState.mCOLRLength) {
+      return Matrix();
+    }
+    const auto* t = reinterpret_cast<const VarAffine2x3*>(
+        aState.COLRv1BaseAddr() + aOffset + transformOffset);
+    return t->AsMatrix(aState);
+  }
+};
+
+struct PaintTranslate : public PaintTransformBase {
+  enum { kFormat = 14 };
+  FWORD dx;
+  FWORD dy;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Translation(aState.F2P(int16_t(dx)),
+                               -aState.F2P(int16_t(dy)));
+  }
+};
+
+struct PaintVarTranslate : public PaintTranslate {
+  enum { kFormat = 15 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Translation(
+        aState.F2P(ApplyVariation(aState, int16_t(dx), varIndexBase)),
+        -aState.F2P(
+            ApplyVariation(aState, int16_t(dy), SatAdd(varIndexBase, 1))));
+  }
+};
+
+struct PaintScale : public PaintTransformBase {
+  enum { kFormat = 16 };
+  F2DOT14 scaleX;
+  F2DOT14 scaleY;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Scaling(float(scaleX), float(scaleY));
+  }
+};
+
+struct PaintVarScale : public PaintScale {
+  enum { kFormat = 17 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Scaling(
+        ApplyVariation(aState, scaleX, varIndexBase),
+        ApplyVariation(aState, scaleY, SatAdd(varIndexBase, 1)));
+  }
+};
+
+struct PaintScaleAroundCenter : public PaintTransformBase {
+  enum { kFormat = 18 };
+  F2DOT14 scaleX;
+  F2DOT14 scaleY;
+  FWORD centerX;
+  FWORD centerY;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(int16_t(centerX)), -aState.F2P(int16_t(centerY)));
+    return Matrix::Translation(center)
+        .PreScale(float(scaleX), float(scaleY))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintVarScaleAroundCenter : public PaintScaleAroundCenter {
+  enum { kFormat = 19 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(ApplyVariation(aState, int16_t(centerX),
+                                           SatAdd(varIndexBase, 2))),
+                 -aState.F2P(ApplyVariation(aState, int16_t(centerY),
+                                            SatAdd(varIndexBase, 3))));
+    return Matrix::Translation(center)
+        .PreScale(ApplyVariation(aState, scaleX, varIndexBase),
+                  ApplyVariation(aState, scaleY, SatAdd(varIndexBase, 1)))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintScaleUniform : public PaintTransformBase {
+  enum { kFormat = 20 };
+  F2DOT14 scale;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Scaling(float(scale), float(scale));
+  }
+};
+
+struct PaintVarScaleUniform : public PaintScaleUniform {
+  enum { kFormat = 21 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    float sc = ApplyVariation(aState, scale, varIndexBase);
+    return Matrix::Scaling(sc, sc);
+  }
+};
+
+struct PaintScaleUniformAroundCenter : public PaintTransformBase {
+  enum { kFormat = 22 };
+  F2DOT14 scale;
+  FWORD centerX;
+  FWORD centerY;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(int16_t(centerX)), -aState.F2P(int16_t(centerY)));
+    return Matrix::Translation(center)
+        .PreScale(float(scale), float(scale))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintVarScaleUniformAroundCenter : public PaintScaleUniformAroundCenter {
+  enum { kFormat = 23 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    float sc = ApplyVariation(aState, scale, varIndexBase);
+    Point center(aState.F2P(ApplyVariation(aState, int16_t(centerX),
+                                           SatAdd(varIndexBase, 1))),
+                 -aState.F2P(ApplyVariation(aState, int16_t(centerY),
+                                            SatAdd(varIndexBase, 2))));
+    return Matrix::Translation(center).PreScale(sc, sc).PreTranslate(-center);
+  }
+};
+
+struct PaintRotate : public PaintTransformBase {
+  enum { kFormat = 24 };
+  F2DOT14 angle;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return Matrix::Rotation(-float(angle) * float(M_PI));
+  }
+};
+
+struct PaintVarRotate : public PaintRotate {
+  enum { kFormat = 25 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    float ang = ApplyVariation(aState, angle, varIndexBase);
+    return Matrix::Rotation(-ang * float(M_PI));
+  }
+};
+
+struct PaintRotateAroundCenter : public PaintTransformBase {
+  enum { kFormat = 26 };
+  F2DOT14 angle;
+  FWORD centerX;
+  FWORD centerY;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(int16_t(centerX)), -aState.F2P(int16_t(centerY)));
+    return Matrix::Translation(center)
+        .PreRotate(-float(angle) * float(M_PI))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintVarRotateAroundCenter : public PaintRotateAroundCenter {
+  enum { kFormat = 27 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    float ang = ApplyVariation(aState, angle, varIndexBase);
+    Point center(aState.F2P(ApplyVariation(aState, int16_t(centerX),
+                                           SatAdd(varIndexBase, 1))),
+                 -aState.F2P(ApplyVariation(aState, int16_t(centerY),
+                                            SatAdd(varIndexBase, 2))));
+    return Matrix::Translation(center)
+        .PreRotate(-ang * float(M_PI))
+        .PreTranslate(-center);
+  }
+};
+
+static inline Matrix SkewMatrix(float aSkewX, float aSkewY) {
+  float xy = tanf(aSkewX * float(M_PI));
+  float yx = tanf(aSkewY * float(M_PI));
+  return std::isnan(xy) || std::isnan(yx) ? Matrix()
+                                          : Matrix(1.0, -yx, xy, 1.0, 0.0, 0.0);
+}
+
+struct PaintSkew : public PaintTransformBase {
+  enum { kFormat = 28 };
+  F2DOT14 xSkewAngle;
+  F2DOT14 ySkewAngle;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return SkewMatrix(float(xSkewAngle), float(ySkewAngle));
+  }
+};
+
+struct PaintVarSkew : public PaintSkew {
+  enum { kFormat = 29 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    return SkewMatrix(
+        float(ApplyVariation(aState, xSkewAngle, varIndexBase)),
+        float(ApplyVariation(aState, ySkewAngle, SatAdd(varIndexBase, 1))));
+  }
+};
+
+struct PaintSkewAroundCenter : public PaintTransformBase {
+  enum { kFormat = 30 };
+  F2DOT14 xSkewAngle;
+  F2DOT14 ySkewAngle;
+  FWORD centerX;
+  FWORD centerY;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(int16_t(centerX)), -aState.F2P(int16_t(centerY)));
+    return Matrix::Translation(center)
+        .PreMultiply(SkewMatrix(float(xSkewAngle), float(ySkewAngle)))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintVarSkewAroundCenter : public PaintSkewAroundCenter {
+  enum { kFormat = 31 };
+  uint32 varIndexBase;
+
+  Matrix GetMatrix(const PaintState& aState, uint32_t aOffset) const {
+    MOZ_ASSERT(format == kFormat);
+    Point center(aState.F2P(ApplyVariation(aState, int16_t(centerX),
+                                           SatAdd(varIndexBase, 2))),
+                 -aState.F2P(ApplyVariation(aState, int16_t(centerY),
+                                            SatAdd(varIndexBase, 3))));
+    return Matrix::Translation(center)
+        .PreMultiply(SkewMatrix(
+            ApplyVariation(aState, xSkewAngle, varIndexBase),
+            ApplyVariation(aState, ySkewAngle, SatAdd(varIndexBase, 1))))
+        .PreTranslate(-center);
+  }
+};
+
+struct PaintComposite {
+  enum { kFormat = 32 };
+  uint8_t format;
+  Offset24 sourcePaintOffset;
+  uint8_t compositeMode;
+  Offset24 backdropPaintOffset;
+
+  enum {
+    COMPOSITE_CLEAR = 0,
+    COMPOSITE_SRC = 1,
+    COMPOSITE_DEST = 2,
+    COMPOSITE_SRC_OVER = 3,
+    COMPOSITE_DEST_OVER = 4,
+    COMPOSITE_SRC_IN = 5,
+    COMPOSITE_DEST_IN = 6,
+    COMPOSITE_SRC_OUT = 7,
+    COMPOSITE_DEST_OUT = 8,
+    COMPOSITE_SRC_ATOP = 9,
+    COMPOSITE_DEST_ATOP = 10,
+    COMPOSITE_XOR = 11,
+    COMPOSITE_PLUS = 12,
+    COMPOSITE_SCREEN = 13,
+    COMPOSITE_OVERLAY = 14,
+    COMPOSITE_DARKEN = 15,
+    COMPOSITE_LIGHTEN = 16,
+    COMPOSITE_COLOR_DODGE = 17,
+    COMPOSITE_COLOR_BURN = 18,
+    COMPOSITE_HARD_LIGHT = 19,
+    COMPOSITE_SOFT_LIGHT = 20,
+    COMPOSITE_DIFFERENCE = 21,
+    COMPOSITE_EXCLUSION = 22,
+    COMPOSITE_MULTIPLY = 23,
+    COMPOSITE_HSL_HUE = 24,
+    COMPOSITE_HSL_SATURATION = 25,
+    COMPOSITE_HSL_COLOR = 26,
+    COMPOSITE_HSL_LUMINOSITY = 27
+  };
+
+  bool Paint(const PaintState& aState, uint32_t aOffset,
+             const Rect* aBounds) const {
+    MOZ_ASSERT(format == kFormat);
+    if (!backdropPaintOffset || !sourcePaintOffset) {
+      return true;
+    }
+    auto mapCompositionMode = [](uint8_t aMode) -> CompositionOp {
+      switch (aMode) {
+        default:
+          return CompositionOp::OP_SOURCE;
+        case COMPOSITE_CLEAR:
+        case COMPOSITE_SRC:
+        case COMPOSITE_DEST:
+          MOZ_ASSERT_UNREACHABLE("should have short-circuited");
+          return CompositionOp::OP_SOURCE;
+        case COMPOSITE_SRC_OVER:
+          return CompositionOp::OP_OVER;
+        case COMPOSITE_DEST_OVER:
+          return CompositionOp::OP_DEST_OVER;
+        case COMPOSITE_SRC_IN:
+          return CompositionOp::OP_IN;
+        case COMPOSITE_DEST_IN:
+          return CompositionOp::OP_DEST_IN;
+        case COMPOSITE_SRC_OUT:
+          return CompositionOp::OP_OUT;
+        case COMPOSITE_DEST_OUT:
+          return CompositionOp::OP_DEST_OUT;
+        case COMPOSITE_SRC_ATOP:
+          return CompositionOp::OP_ATOP;
+        case COMPOSITE_DEST_ATOP:
+          return CompositionOp::OP_DEST_ATOP;
+        case COMPOSITE_XOR:
+          return CompositionOp::OP_XOR;
+        case COMPOSITE_PLUS:
+          return CompositionOp::OP_ADD;
+        case COMPOSITE_SCREEN:
+          return CompositionOp::OP_SCREEN;
+        case COMPOSITE_OVERLAY:
+          return CompositionOp::OP_OVERLAY;
+        case COMPOSITE_DARKEN:
+          return CompositionOp::OP_DARKEN;
+        case COMPOSITE_LIGHTEN:
+          return CompositionOp::OP_LIGHTEN;
+        case COMPOSITE_COLOR_DODGE:
+          return CompositionOp::OP_COLOR_DODGE;
+        case COMPOSITE_COLOR_BURN:
+          return CompositionOp::OP_COLOR_BURN;
+        case COMPOSITE_HARD_LIGHT:
+          return CompositionOp::OP_HARD_LIGHT;
+        case COMPOSITE_SOFT_LIGHT:
+          return CompositionOp::OP_SOFT_LIGHT;
+        case COMPOSITE_DIFFERENCE:
+          return CompositionOp::OP_DIFFERENCE;
+        case COMPOSITE_EXCLUSION:
+          return CompositionOp::OP_EXCLUSION;
+        case COMPOSITE_MULTIPLY:
+          return CompositionOp::OP_MULTIPLY;
+        case COMPOSITE_HSL_HUE:
+          return CompositionOp::OP_HUE;
+        case COMPOSITE_HSL_SATURATION:
+          return CompositionOp::OP_SATURATION;
+        case COMPOSITE_HSL_COLOR:
+          return CompositionOp::OP_COLOR;
+        case COMPOSITE_HSL_LUMINOSITY:
+          return CompositionOp::OP_LUMINOSITY;
+      }
+    };
+    // Short-circuit cases:
+    if (compositeMode == COMPOSITE_CLEAR) {
+      return true;
+    }
+    if (compositeMode == COMPOSITE_SRC) {
+      return DispatchPaint(aState, aOffset + sourcePaintOffset, aBounds);
+    }
+    if (compositeMode == COMPOSITE_DEST) {
+      return DispatchPaint(aState, aOffset + backdropPaintOffset, aBounds);
+    }
+
+    // We need bounds for the temporary surfaces; so if we didn't have
+    // explicitly-provided bounds from a clipList entry for the top-level
+    // glyph, then we need to determine the bounding rect here.
+    Rect bounds = aBounds ? *aBounds : GetBoundingRect(aState, aOffset);
+    if (bounds.IsEmpty()) {
+      return true;
+    }
+    bounds.RoundOut();
+
+    PaintState state = aState;
+    state.mDrawOptions.mCompositionOp = CompositionOp::OP_OVER;
+    IntSize intSize(int(bounds.width), int(bounds.height));
+
+    if (!aState.mDrawTarget->CanCreateSimilarDrawTarget(
+            intSize, SurfaceFormat::B8G8R8A8)) {
+      // We're not going to be able to render this, so just bail out.
+      // (Returning true rather than false means we'll just not paint this
+      // part of the glyph, but won't return an error and likely fall back
+      // to an ugly black blob.)
+      return true;
+    }
+
+    // Draw the backdrop paint graph to a temporary surface.
+    RefPtr backdrop = aState.mDrawTarget->CreateSimilarDrawTarget(
+        intSize, SurfaceFormat::B8G8R8A8);
+    if (!backdrop) {
+      return true;
+    }
+    backdrop->SetTransform(Matrix::Translation(-bounds.TopLeft()));
+    state.mDrawTarget = backdrop;
+    if (!DispatchPaint(state, aOffset + backdropPaintOffset, &bounds)) {
+      return false;
+    }
+
+    // Draw the source paint graph to another temp surface.
+    RefPtr source = aState.mDrawTarget->CreateSimilarDrawTarget(
+        intSize, SurfaceFormat::B8G8R8A8);
+    if (!source) {
+      return true;
+    }
+    source->SetTransform(Matrix::Translation(-bounds.TopLeft()));
+    state.mDrawTarget = source;
+    if (!DispatchPaint(state, aOffset + sourcePaintOffset, &bounds)) {
+      return false;
+    }
+
+    // Composite the source onto the backdrop using the specified operation.
+    Rect localBounds(Point(), bounds.Size());
+    RefPtr snapshot = source->Snapshot();
+    backdrop->SetTransform(Matrix());
+    backdrop->DrawSurface(snapshot, localBounds, localBounds,
+                          DrawSurfaceOptions(),
+                          DrawOptions(1.0, mapCompositionMode(compositeMode)));
+
+    // And copy the composited result to our final destination.
+    snapshot = backdrop->Snapshot();
+    aState.mDrawTarget->DrawSurface(snapshot, bounds, localBounds);
+
+    return true;
+  }
+
+  Rect GetBoundingRect(const PaintState& aState, uint32_t aOffset) const {
+    if (!backdropPaintOffset || !sourcePaintOffset) {
+      return Rect();
+    }
+    // For now, just return the maximal bounds that could result; this could be
+    // smarter, returning just one of the rects or their intersection when
+    // appropriate for the composite mode in effect.
+    return DispatchGetBounds(aState, aOffset + backdropPaintOffset)
+        .Union(DispatchGetBounds(aState, aOffset + sourcePaintOffset));
+  }
+};
+
+#pragma pack()
+
+const BaseGlyphPaintRecord* COLRv1Header::GetBaseGlyphPaint(
+    uint32_t aGlyphId) const {
+  const auto* list = baseGlyphList();
+  if (!list) {
+    return nullptr;
+  }
+  auto compare = [](const void* key, const void* data) -> int {
+    uint32_t glyphId = (uint32_t)(uintptr_t)key;
+    const auto* paintRecord =
+        reinterpret_cast<const BaseGlyphPaintRecord*>(data);
+    uint32_t baseGlyphId = uint16_t(paintRecord->glyphID);
+    if (baseGlyphId == glyphId) {
+      return 0;
+    }
+    return baseGlyphId > glyphId ? -1 : 1;
+  };
+  return reinterpret_cast<const BaseGlyphPaintRecord*>(
+      bsearch((void*)(uintptr_t)aGlyphId, list + 1,
+              uint32_t(list->numBaseGlyphPaintRecords),
+              sizeof(BaseGlyphPaintRecord), compare));
+}
+
+#define DO_CASE_VAR(T) \
+  DO_CASE(Paint##T);   \
+  DO_CASE(PaintVar##T)
+
+// Process paint table at aOffset from start of COLRv1 table.
+static bool DispatchPaint(const PaintState& aState, uint32_t aOffset,
+                          const Rect* aBounds) {
+  if (aOffset >= aState.mCOLRLength) {
+    return false;
+  }
+
+  const char* paint = aState.COLRv1BaseAddr() + aOffset;
+  // All paint table formats start with an 8-bit 'format' field.
+  uint8_t format = uint8_t(*paint);
+
+#define DO_CASE(T)                                                         \
+  case T::kFormat:                                                         \
+    return aOffset + sizeof(T) <= aState.mCOLRLength                       \
+               ? reinterpret_cast<const T*>(paint)->Paint(aState, aOffset, \
+                                                          aBounds)         \
+               : false
+
+  switch (format) {
+    DO_CASE(PaintColrLayers);
+    DO_CASE_VAR(Solid);
+    DO_CASE_VAR(LinearGradient);
+    DO_CASE_VAR(RadialGradient);
+    DO_CASE_VAR(SweepGradient);
+    DO_CASE(PaintGlyph);
+    DO_CASE(PaintColrGlyph);
+    DO_CASE_VAR(Transform);
+    DO_CASE_VAR(Translate);
+    DO_CASE_VAR(Scale);
+    DO_CASE_VAR(ScaleAroundCenter);
+    DO_CASE_VAR(ScaleUniform);
+    DO_CASE_VAR(ScaleUniformAroundCenter);
+    DO_CASE_VAR(Rotate);
+    DO_CASE_VAR(RotateAroundCenter);
+    DO_CASE_VAR(Skew);
+    DO_CASE_VAR(SkewAroundCenter);
+    DO_CASE(PaintComposite);
+    default:
+      break;
+  }
+
+#undef DO_CASE
+
+  return false;
+}
+
+// Get a gfx::Pattern corresponding to the given paint table, if it is a
+// simple format that can be used as a fill (not a sub-graph).
+static UniquePtr<Pattern> DispatchMakePattern(const PaintState& aState,
+                                              uint32_t aOffset) {
+  if (aOffset >= aState.mCOLRLength) {
+    return nullptr;
+  }
+
+  const char* paint = aState.COLRv1BaseAddr() + aOffset;
+  // All paint table formats start with an 8-bit 'format' field.
+  uint8_t format = uint8_t(*paint);
+
+#define DO_CASE(T)                                                       \
+  case T::kFormat:                                                       \
+    return aOffset + sizeof(T) <= aState.mCOLRLength                     \
+               ? reinterpret_cast<const T*>(paint)->MakePattern(aState,  \
+                                                                aOffset) \
+               : nullptr;
+
+  switch (format) {
+    DO_CASE_VAR(Solid);
+    DO_CASE_VAR(LinearGradient);
+    DO_CASE_VAR(RadialGradient);
+    DO_CASE_VAR(SweepGradient);
+    default:
+      break;
+  }
+
+#undef DO_CASE
+
+  return nullptr;
+}
+
+static Matrix DispatchGetMatrix(const PaintState& aState, uint32_t aOffset) {
+  if (aOffset >= aState.mCOLRLength) {
+    return Matrix();
+  }
+
+  const char* paint = aState.COLRv1BaseAddr() + aOffset;
+  // All paint table formats start with an 8-bit 'format' field.
+  uint8_t format = uint8_t(*paint);
+
+#define DO_CASE(T)                                                             \
+  case T::kFormat:                                                             \
+    return aOffset + sizeof(T) <= aState.mCOLRLength                           \
+               ? reinterpret_cast<const T*>(paint)->GetMatrix(aState, aOffset) \
+               : Matrix();
+
+  switch (format) {
+    DO_CASE_VAR(Transform);
+    DO_CASE_VAR(Translate);
+    DO_CASE_VAR(Scale);
+    DO_CASE_VAR(ScaleAroundCenter);
+    DO_CASE_VAR(ScaleUniform);
+    DO_CASE_VAR(ScaleUniformAroundCenter);
+    DO_CASE_VAR(Rotate);
+    DO_CASE_VAR(RotateAroundCenter);
+    DO_CASE_VAR(Skew);
+    DO_CASE_VAR(SkewAroundCenter);
+    default:
+      break;
+  }
+
+#undef DO_CASE
+
+  return Matrix();
+}
+
+static Rect DispatchGetBounds(const PaintState& aState, uint32_t aOffset) {
+  if (aOffset >= aState.mCOLRLength) {
+    return Rect();
+  }
+
+  const char* paint = aState.COLRv1BaseAddr() + aOffset;
+  // All paint table formats start with an 8-bit 'format' field.
+  uint8_t format = uint8_t(*paint);
+
+#define DO_CASE(T)                                                           \
+  case T::kFormat:                                                           \
+    return aOffset + sizeof(T) <= aState.mCOLRLength                         \
+               ? reinterpret_cast<const T*>(paint)->GetBoundingRect(aState,  \
+                                                                    aOffset) \
+               : Rect();
+
+  switch (format) {
+    DO_CASE(PaintColrLayers);
+    DO_CASE_VAR(Solid);
+    DO_CASE_VAR(LinearGradient);
+    DO_CASE_VAR(RadialGradient);
+    DO_CASE_VAR(SweepGradient);
+    DO_CASE(PaintGlyph);
+    DO_CASE(PaintColrGlyph);
+    DO_CASE_VAR(Transform);
+    DO_CASE_VAR(Translate);
+    DO_CASE_VAR(Scale);
+    DO_CASE_VAR(ScaleAroundCenter);
+    DO_CASE_VAR(ScaleUniform);
+    DO_CASE_VAR(ScaleUniformAroundCenter);
+    DO_CASE_VAR(Rotate);
+    DO_CASE_VAR(RotateAroundCenter);
+    DO_CASE_VAR(Skew);
+    DO_CASE_VAR(SkewAroundCenter);
+    DO_CASE(PaintComposite);
+    default:
+      break;
+  }
+
+#undef DO_CASE
+
+  return Rect();
+}
+
+#undef DO_CASE_VAR
+
+bool COLRHeader::Validate(uint64_t aLength) const {
+  uint64_t count;
+  if ((count = numBaseGlyphRecords)) {
+    if (baseGlyphRecordsOffset + count * sizeof(BaseGlyphRecord) > aLength) {
+      return false;
+    }
+  }
+  if ((count = numLayerRecords)) {
+    if (layerRecordsOffset + count * sizeof(LayerRecord) > aLength) {
+      return false;
+    }
+  }
+  // Check ordering of baseGlyphRecords, and that layer indices are in bounds.
+  int32_t lastGlyphId = -1;
+  const auto* baseGlyph = reinterpret_cast<const BaseGlyphRecord*>(
+      reinterpret_cast<const char*>(this) + baseGlyphRecordsOffset);
+  for (uint16_t i = 0; i < uint16_t(numBaseGlyphRecords); i++, baseGlyph++) {
+    uint16_t glyphId = baseGlyph->glyphId;
+    if (lastGlyphId >= int32_t(glyphId)) {
+      return false;
+    }
+    if (uint32_t(baseGlyph->firstLayerIndex) + uint32_t(baseGlyph->numLayers) >
+        uint32_t(numLayerRecords)) {
+      return false;
+    }
+    lastGlyphId = glyphId;
+  }
+  // We don't need to validate all the layer paletteEntryIndex fields here,
+  // because PaintState.GetColor will range-check them at paint time.
+  return true;
+}
+
+bool COLRv1Header::Validate(uint64_t aLength) const {
+  if (!base.Validate(aLength)) {
+    return false;
+  }
+  if (baseGlyphListOffset + sizeof(BaseGlyphList) > aLength ||
+      layerListOffset + sizeof(LayerList) > aLength ||
+      clipListOffset + sizeof(ClipList) > aLength ||
+      varIndexMapOffset + sizeof(DeltaSetIndexMap) > aLength ||
+      itemVariationStoreOffset + sizeof(ItemVariationStore) > aLength) {
+    return false;
+  }
+  const auto* b = baseGlyphList();
+  if (b && !b->Validate(this, aLength)) {
+    return false;
+  }
+  const auto* l = layerList();
+  if (l && !l->Validate(this, aLength)) {
+    return false;
+  }
+  const auto* c = clipList();
+  if (c && !c->Validate(this, aLength)) {
+    return false;
+  }
+  const auto* v = varIndexMap();
+  if (v && !v->Validate(this, aLength)) {
+    return false;
+  }
+  const auto* i = itemVariationStore();
+  if (i && !i->Validate(this, aLength)) {
+    return false;
+  }
+  return true;
+}
+
+bool BaseGlyphList::Validate(const COLRv1Header* aHeader,
+                             uint64_t aLength) const {
+  uint64_t count = numBaseGlyphPaintRecords;
+  if (aHeader->baseGlyphListOffset + sizeof(BaseGlyphList) +
+          count * sizeof(BaseGlyphPaintRecord) >
+      aLength) {
+    return false;
+  }
+  // Check ordering of baseGlyphPaint records.
+  const auto* records = baseGlyphPaintRecords();
+  int32_t prevGlyphID = -1;
+  for (uint32_t i = 0; i < numBaseGlyphPaintRecords; ++i) {
+    const auto& base = records[i];
+    if (int32_t(uint16_t(base.glyphID)) <= prevGlyphID) {
+      return false;
+    }
+    prevGlyphID = base.glyphID;
+  }
+  return true;
+}
+
+bool LayerList::Validate(const COLRv1Header* aHeader, uint64_t aLength) const {
+  // Check that paintOffsets array fits.
+  uint64_t count = numLayers;
+  uint32_t listOffset = aHeader->layerListOffset;
+  if (listOffset + sizeof(LayerList) + count * sizeof(uint32) > aLength) {
+    return false;
+  }
+  // Check that values in paintOffsets are within bounds.
+  const auto* offsets = paintOffsets();
+  for (uint32_t i = 0; i < count; i++) {
+    if (listOffset + offsets[i] >= aLength) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool Clip::Validate(const COLRv1Header* aHeader, uint64_t aLength) const {
+  uint32_t offset = aHeader->clipListOffset + clipBoxOffset;
+  if (offset >= aLength) {
+    return false;
+  }
+  // ClipBox format begins with a 1-byte format field.
+  const uint8_t* box = reinterpret_cast<const uint8_t*>(aHeader) + offset;
+  switch (*box) {
+    case 1:
+      if (offset <= aLength - sizeof(ClipBoxFormat1)) {
+        return true;
+      }
+      break;
+    case 2:
+      if (offset <= aLength - sizeof(ClipBoxFormat2)) {
+        return true;
+      }
+      break;
+    default:
+      // unknown ClipBoxFormat
+      break;
+  }
+  return false;
+}
+
+bool ClipList::Validate(const COLRv1Header* aHeader, uint64_t aLength) const {
+  uint64_t count = numClips;
+  if (aHeader->clipListOffset + sizeof(ClipList) + count * sizeof(Clip) >
+      aLength) {
+    return false;
+  }
+  // Check ordering of clip records, and that they are within bounds.
+  const auto* clipArray = clips();
+  int32_t prevEnd = -1;
+  for (uint32_t i = 0; i < count; ++i) {
+    const auto& clip = clipArray[i];
+    if (int32_t(uint16_t(clip.startGlyphID)) <= prevEnd) {
+      return false;
+    }
+    if (!clip.Validate(aHeader, aLength)) {
+      return false;
+    }
+    prevEnd = uint16_t(clip.endGlyphID);
+  }
+  return true;
+}
+
+bool DeltaSetIndexMap::Validate(const COLRv1Header* aHeader,
+                                uint64_t aLength) const {
+  uint64_t entrySize = ((entryFormat & MAP_ENTRY_SIZE_MASK) >> 4) + 1;
+  uint64_t mapCount;
+  uint64_t baseSize;
+  switch (format) {
+    case 0:
+      mapCount = uint32_t(v0.mapCount);
+      baseSize = 4;
+      break;
+    case 1:
+      mapCount = uint32_t(v1.mapCount);
+      baseSize = 6;
+      break;
+    default:
+      return false;
+  }
+  if (aHeader->varIndexMapOffset + baseSize + mapCount * entrySize > aLength) {
+    return false;
+  }
+  return true;
+}
+
+bool ItemVariationStore::Validate(const COLRv1Header* aHeader,
+                                  uint64_t aLength) const {
+  uint64_t offset = reinterpret_cast<const char*>(this) -
+                    reinterpret_cast<const char*>(aHeader);
+  if (offset + variationRegionListOffset + sizeof(VariationRegionList) >
+      aLength) {
+    return false;
+  }
+  if (!variationRegionList()->Validate(aHeader, aLength)) {
+    return false;
+  }
+  uint16_t count = itemVariationDataCount;
+  if (offset + sizeof(ItemVariationStore) + count * sizeof(Offset32) >
+      aLength) {
+    return false;
+  }
+  const auto* ivdOffsets = itemVariationDataOffsets();
+  for (uint16_t i = 0; i < count; ++i) {
+    uint32_t o = ivdOffsets[i];
+    if (offset + o + sizeof(ItemVariationData) > aLength) {
+      return false;
+    }
+    const auto* variationData = reinterpret_cast<const ItemVariationData*>(
+        reinterpret_cast<const char*>(this) + ivdOffsets[i]);
+    if (!variationData->Validate(aHeader, aLength)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool ItemVariationData::Validate(const COLRv1Header* aHeader,
+                                 uint64_t aLength) const {
+  if (reinterpret_cast<const char*>(regionIndexes() +
+                                    uint16_t(regionIndexCount)) >
+      reinterpret_cast<const char*>(aHeader) + aLength) {
+    return false;
+  }
+  uint16_t wordDeltaCount = this->wordDeltaCount;
+  bool longWords = wordDeltaCount & LONG_WORDS;
+  wordDeltaCount &= WORD_DELTA_COUNT_MASK;
+  uint32_t deltaSetSize =
+      (uint16_t(regionIndexCount) + uint16_t(wordDeltaCount)) << longWords;
+  if (reinterpret_cast<const char*>(deltaSets()) +
+          uint16_t(itemCount) * deltaSetSize >
+      reinterpret_cast<const char*>(aHeader) + aLength) {
+    return false;
+  }
+  return true;
+}
+
+}  // end anonymous namespace
+
+namespace mozilla::gfx {
+
+bool COLRFonts::ValidateColorGlyphs(hb_blob_t* aCOLR, hb_blob_t* aCPAL) {
+  struct ColorRecord {
+    uint8_t blue;
+    uint8_t green;
+    uint8_t red;
+    uint8_t alpha;
+  };
+
+  struct CPALHeaderVersion0 {
+    uint16 version;
+    uint16 numPaletteEntries;
+    uint16 numPalettes;
+    uint16 numColorRecords;
+    Offset32 colorRecordsArrayOffset;
+    // uint16 	colorRecordIndices[numPalettes];
+    const uint16* colorRecordIndices() const {
+      return reinterpret_cast<const uint16*>(this + 1);
+    }
+  };
+
+  unsigned int cpalLength;
+  const CPALHeaderVersion0* cpal = reinterpret_cast<const CPALHeaderVersion0*>(
+      hb_blob_get_data(aCPAL, &cpalLength));
+  if (!cpal || cpalLength < sizeof(CPALHeaderVersion0)) {
+    return false;
+  }
+
+  // We can handle either version 0 or 1.
+  if (uint16_t(cpal->version) > 1) {
+    return false;
+  }
+
+  uint16_t numPaletteEntries = cpal->numPaletteEntries;
+  uint16_t numPalettes = cpal->numPalettes;
+  uint16_t numColorRecords = cpal->numColorRecords;
+  uint32_t colorRecordsArrayOffset = cpal->colorRecordsArrayOffset;
+  const auto* indices = cpal->colorRecordIndices();
+  if (colorRecordsArrayOffset >= cpalLength) {
+    return false;
+  }
+  if (!numPaletteEntries || !numPalettes ||
+      numColorRecords < numPaletteEntries) {
+    return false;
+  }
+  if (sizeof(ColorRecord) * numColorRecords >
+      cpalLength - colorRecordsArrayOffset) {
+    return false;
+  }
+  if (sizeof(uint16) * numPalettes > cpalLength - sizeof(CPALHeaderVersion0)) {
+    return false;
+  }
+  for (uint16_t i = 0; i < numPalettes; ++i) {
+    uint32_t index = indices[i];
+    if (index + numPaletteEntries > numColorRecords) {
+      return false;
+    }
+  }
+
+  // The additional fields in CPALv1 are not checked here; the harfbuzz code
+  // handles reading them safely.
+
+  unsigned int colrLength;
+  const COLRHeader* colr =
+      reinterpret_cast<const COLRHeader*>(hb_blob_get_data(aCOLR, &colrLength));
+  if (!colr || colrLength < sizeof(COLRHeader)) {
+    return false;
+  }
+
+  if (uint16_t(colr->version) == 1) {
+    return StaticPrefs::gfx_font_rendering_colr_v1_enabled() &&
+           colrLength >= sizeof(COLRv1Header) &&
+           reinterpret_cast<const COLRv1Header*>(colr)->Validate(colrLength);
+  }
+
+  if (uint16_t(colr->version) != 0) {
+    // We only support version 1 (above) or version 0 headers.
+    return false;
+  }
+
+  return colr->Validate(colrLength);
+}
+
+const COLRFonts::GlyphLayers* COLRFonts::GetGlyphLayers(hb_blob_t* aCOLR,
+                                                        uint32_t aGlyphId) {
+  unsigned int length;
+  const COLRHeader* colr =
+      reinterpret_cast<const COLRHeader*>(hb_blob_get_data(aCOLR, &length));
+  // This should never be called unless we have checked that the COLR table is
+  // structurally valid, so it will be safe to read the header fields.
+  MOZ_RELEASE_ASSERT(colr && length >= sizeof(COLRHeader), "bad COLR table!");
+  auto compareBaseGlyph = [](const void* key, const void* data) -> int {
+    uint32_t glyphId = (uint32_t)(uintptr_t)key;
+    const auto* baseGlyph = reinterpret_cast<const BaseGlyphRecord*>(data);
+    uint32_t baseGlyphId = uint16_t(baseGlyph->glyphId);
+    if (baseGlyphId == glyphId) {
+      return 0;
+    }
+    return baseGlyphId > glyphId ? -1 : 1;
+  };
+  return reinterpret_cast<const GlyphLayers*>(
+      bsearch((void*)(uintptr_t)aGlyphId, colr->GetBaseGlyphRecords(),
+              uint16_t(colr->numBaseGlyphRecords), sizeof(BaseGlyphRecord),
+              compareBaseGlyph));
+}
+
+bool COLRFonts::PaintGlyphLayers(
+    hb_blob_t* aCOLR, hb_face_t* aFace, const GlyphLayers* aLayers,
+    DrawTarget* aDrawTarget, layout::TextDrawTarget* aTextDrawer,
+    ScaledFont* aScaledFont, DrawOptions aDrawOptions, const Point& aPoint,
+    const sRGBColor& aCurrentColor, const nsTArray<sRGBColor>* aColors) {
+  const auto* glyphRecord = reinterpret_cast<const BaseGlyphRecord*>(aLayers);
+  // Default to opaque rendering (non-webrender applies alpha with a layer)
+  float alpha = 1.0;
+  if (aTextDrawer) {
+    // defaultColor is the one that comes from CSS, so it has transparency info.
+    bool hasComplexTransparency =
+        0.0 < aCurrentColor.a && aCurrentColor.a < 1.0;
+    if (hasComplexTransparency && uint16_t(glyphRecord->numLayers) > 1) {
+      // WebRender doesn't support drawing multi-layer transparent color-glyphs,
+      // as it requires compositing all the layers before applying transparency.
+      // (pretend to succeed, output doesn't matter, we will emit a blob)
+      aTextDrawer->FoundUnsupportedFeature();
+      return true;
+    }
+
+    // If we get here, then either alpha is 0 or 1, or there's only one layer
+    // which shouldn't have composition issues. In all of these cases, applying
+    // transparency directly to the glyph should work perfectly fine.
+    //
+    // Note that we must still emit completely transparent emoji, because they
+    // might be wrapped in a shadow that uses the text run's glyphs.
+    alpha = aCurrentColor.a;
+  }
+
+  unsigned int length;
+  const COLRHeader* colr =
+      reinterpret_cast<const COLRHeader*>(hb_blob_get_data(aCOLR, &length));
+  PaintState state{{colr},
+                   aColors->Elements(),
+                   aDrawTarget,
+                   aScaledFont,
+                   nullptr,  // variations not needed
+                   aDrawOptions,
+                   length,
+                   aCurrentColor,
+                   0.0,  // fontUnitsToPixels not needed
+                   uint16_t(aColors->Length()),
+                   0,
+                   nullptr};
+  return glyphRecord->Paint(state, alpha, aPoint);
+}
+
+const COLRFonts::GlyphPaintGraph* COLRFonts::GetGlyphPaintGraph(
+    hb_blob_t* aCOLR, uint32_t aGlyphId) {
+  if (!StaticPrefs::gfx_font_rendering_colr_v1_enabled()) {
+    return nullptr;
+  }
+  unsigned int blobLength;
+  const auto* colr =
+      reinterpret_cast<const COLRHeader*>(hb_blob_get_data(aCOLR, &blobLength));
+  MOZ_ASSERT(colr, "Cannot get COLR raw data");
+  MOZ_ASSERT(blobLength >= sizeof(COLRHeader), "COLR data too small");
+
+  uint16_t version = colr->version;
+  if (version == 1) {
+    MOZ_ASSERT(blobLength >= sizeof(COLRv1Header), "COLRv1 data too small");
+    const auto* colrv1 = reinterpret_cast<const COLRv1Header*>(colr);
+    return reinterpret_cast<const GlyphPaintGraph*>(
+        colrv1->GetBaseGlyphPaint(aGlyphId));
+  }
+
+  return nullptr;
+}
+
+bool COLRFonts::PaintGlyphGraph(
+    hb_blob_t* aCOLR, hb_font_t* aFont, const GlyphPaintGraph* aPaintGraph,
+    DrawTarget* aDrawTarget, layout::TextDrawTarget* aTextDrawer,
+    ScaledFont* aScaledFont, DrawOptions aDrawOptions, const Point& aPoint,
+    const sRGBColor& aCurrentColor, const nsTArray<sRGBColor>* aColors,
+    uint32_t aGlyphId, float aFontUnitsToPixels) {
+  if (aTextDrawer) {
+    // Currently we always punt to a blob for COLRv1 glyphs.
+    aTextDrawer->FoundUnsupportedFeature();
+    return true;
+  }
+
+  unsigned int coordCount;
+  const int* coords = hb_font_get_var_coords_normalized(aFont, &coordCount);
+
+  AutoTArray<uint32_t, 32> visitedOffsets;
+  PaintState state{{nullptr},
+                   aColors->Elements(),
+                   aDrawTarget,
+                   aScaledFont,
+                   coords,
+                   aDrawOptions,
+                   hb_blob_get_length(aCOLR),
+                   aCurrentColor,
+                   aFontUnitsToPixels,
+                   uint16_t(aColors->Length()),
+                   uint16_t(coordCount),
+                   &visitedOffsets};
+  state.mHeader.v1 =
+      reinterpret_cast<const COLRv1Header*>(hb_blob_get_data(aCOLR, nullptr));
+  AutoRestoreTransform saveTransform(aDrawTarget);
+  aDrawTarget->ConcatTransform(Matrix::Translation(aPoint));
+  return PaintColrGlyph::DoPaint(
+      state, reinterpret_cast<const BaseGlyphPaintRecord*>(aPaintGraph),
+      aGlyphId, nullptr);
+}
+
+Rect COLRFonts::GetColorGlyphBounds(hb_blob_t* aCOLR, hb_font_t* aFont,
+                                    uint32_t aGlyphId, DrawTarget* aDrawTarget,
+                                    ScaledFont* aScaledFont,
+                                    float aFontUnitsToPixels) {
+  unsigned int coordCount;
+  const int* coords = hb_font_get_var_coords_normalized(aFont, &coordCount);
+
+  AutoTArray<uint32_t, 32> visitedOffsets;
+  PaintState state{{nullptr},
+                   nullptr,  // palette is not needed
+                   aDrawTarget,
+                   aScaledFont,
+                   coords,
+                   DrawOptions(),
+                   hb_blob_get_length(aCOLR),
+                   sRGBColor(),
+                   aFontUnitsToPixels,
+                   0,  // numPaletteEntries
+                   uint16_t(coordCount),
+                   &visitedOffsets};
+  state.mHeader.v1 =
+      reinterpret_cast<const COLRv1Header*>(hb_blob_get_data(aCOLR, nullptr));
+  MOZ_ASSERT(uint16_t(state.mHeader.v1->base.version) == 1);
+  // If a clip rect is provided, return this as the glyph bounds.
+  const auto* clipList = state.mHeader.v1->clipList();
+  if (clipList) {
+    const auto* clip = clipList->GetClip(aGlyphId);
+    if (clip) {
+      return clip->GetRect(state);
+    }
+  }
+  // Otherwise, compute bounds by walking the paint graph.
+  const auto* base = state.mHeader.v1->GetBaseGlyphPaint(aGlyphId);
+  if (base) {
+    return DispatchGetBounds(
+        state, state.mHeader.v1->baseGlyphListOffset + base->paintOffset);
+  }
+  return Rect();
+}
+
+uint16_t COLRFonts::GetColrTableVersion(hb_blob_t* aCOLR) {
+  unsigned int blobLength;
+  const auto* colr =
+      reinterpret_cast<const COLRHeader*>(hb_blob_get_data(aCOLR, &blobLength));
+  MOZ_ASSERT(colr, "Cannot get COLR raw data");
+  MOZ_ASSERT(blobLength >= sizeof(COLRHeader), "COLR data too small");
+  return colr->version;
+}
+
+UniquePtr<nsTArray<sRGBColor>> COLRFonts::SetupColorPalette(
+    hb_face_t* aFace, const FontPaletteValueSet* aPaletteValueSet,
+    nsAtom* aFontPalette, const nsACString& aFamilyName) {
+  // Find the base color palette to use, if there are multiple available;
+  // default to first in the font, if nothing matches what is requested.
+  unsigned int paletteIndex = 0;
+  unsigned int count = hb_ot_color_palette_get_count(aFace);
+  MOZ_ASSERT(count > 0, "No palettes? Font should have been rejected!");
+
+  const FontPaletteValueSet::PaletteValues* fpv = nullptr;
+  if (aFontPalette && aFontPalette != nsGkAtoms::normal &&
+      (count > 1 || aPaletteValueSet)) {
+    auto findPalette = [&](hb_ot_color_palette_flags_t flag) -> unsigned int {
+      MOZ_ASSERT(flag != HB_OT_COLOR_PALETTE_FLAG_DEFAULT);
+      for (unsigned int i = 0; i < count; ++i) {
+        if (hb_ot_color_palette_get_flags(aFace, i) & flag) {
+          return i;
+        }
+      }
+      return 0;
+    };
+
+    if (aFontPalette == nsGkAtoms::light) {
+      paletteIndex =
+          findPalette(HB_OT_COLOR_PALETTE_FLAG_USABLE_WITH_LIGHT_BACKGROUND);
+    } else if (aFontPalette == nsGkAtoms::dark) {
+      paletteIndex =
+          findPalette(HB_OT_COLOR_PALETTE_FLAG_USABLE_WITH_DARK_BACKGROUND);
+    } else {
+      if (aPaletteValueSet) {
+        if ((fpv = aPaletteValueSet->Lookup(aFontPalette, aFamilyName))) {
+          if (fpv->mBasePalette >= 0 && fpv->mBasePalette < int32_t(count)) {
+            paletteIndex = fpv->mBasePalette;
+          } else if (fpv->mBasePalette ==
+                     FontPaletteValueSet::PaletteValues::kLight) {
+            paletteIndex = findPalette(
+                HB_OT_COLOR_PALETTE_FLAG_USABLE_WITH_LIGHT_BACKGROUND);
+          } else if (fpv->mBasePalette ==
+                     FontPaletteValueSet::PaletteValues::kDark) {
+            paletteIndex = findPalette(
+                HB_OT_COLOR_PALETTE_FLAG_USABLE_WITH_DARK_BACKGROUND);
+          }
+        }
+      }
+    }
+  }
+
+  // Collect the palette colors and convert them to sRGBColor values.
+  count =
+      hb_ot_color_palette_get_colors(aFace, paletteIndex, 0, nullptr, nullptr);
+  nsTArray<hb_color_t> colors;
+  colors.SetLength(count);
+  hb_ot_color_palette_get_colors(aFace, paletteIndex, 0, &count,
+                                 colors.Elements());
+
+  auto palette = MakeUnique<nsTArray<sRGBColor>>();
+  palette->SetCapacity(count);
+  for (const auto c : colors) {
+    palette->AppendElement(
+        sRGBColor(hb_color_get_red(c) / 255.0, hb_color_get_green(c) / 255.0,
+                  hb_color_get_blue(c) / 255.0, hb_color_get_alpha(c) / 255.0));
+  }
+
+  // Apply @font-palette-values overrides, if present.
+  if (fpv) {
+    for (const auto overrideColor : fpv->mOverrides) {
+      if (overrideColor.mIndex < palette->Length()) {
+        (*palette)[overrideColor.mIndex] = overrideColor.mColor;
+      }
+    }
+  }
+
+  return palette;
+}
+
+const FontPaletteValueSet::PaletteValues* FontPaletteValueSet::Lookup(
+    nsAtom* aName, const nsACString& aFamily) const {
+  nsAutoCString family(aFamily);
+  ToLowerCase(family);
+  if (const HashEntry* entry =
+          mValues.GetEntry(PaletteHashKey(aName, family))) {
+    return &entry->mValue;
+  }
+  return nullptr;
+}
+
+FontPaletteValueSet::PaletteValues* FontPaletteValueSet::Insert(
+    nsAtom* aName, const nsACString& aFamily) {
+  nsAutoCString family(aFamily);
+  ToLowerCase(family);
+  HashEntry* entry = mValues.PutEntry(PaletteHashKey(aName, family));
+  return &entry->mValue;
+}
+
+}  // end namespace mozilla::gfx