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diff --git a/gfx/2d/PatternHelpers.h b/gfx/2d/PatternHelpers.h
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+++ b/gfx/2d/PatternHelpers.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _MOZILLA_GFX_PATTERNHELPERS_H
+#define _MOZILLA_GFX_PATTERNHELPERS_H
+
+#include "mozilla/Alignment.h"
+#include "mozilla/gfx/2D.h"
+
+namespace mozilla {
+namespace gfx {
+
+/**
+ * This class is used to allow general pattern creation functions to return
+ * any type of pattern via an out-paramater without allocating a pattern
+ * instance on the free-store (an instance of this class being created on the
+ * stack before passing it in to the creation function). Without this class
+ * writing pattern creation functions would be a pain since Pattern objects are
+ * not reference counted, making lifetime management of instances created on
+ * the free-store and returned from a creation function hazardous. Besides
+ * that, in the case that ColorPattern's are expected to be common, it is
+ * particularly desirable to avoid the overhead of allocating on the
+ * free-store.
+ */
+class GeneralPattern final {
+ public:
+  explicit GeneralPattern() = default;
+
+  GeneralPattern(const GeneralPattern& aOther) {}
+
+  ~GeneralPattern() {
+    if (mPattern) {
+      mPattern->~Pattern();
+    }
+  }
+
+  Pattern* Init(const Pattern& aPattern) {
+    MOZ_ASSERT(!mPattern);
+    switch (aPattern.GetType()) {
+      case PatternType::COLOR:
+        mPattern = new (mColorPattern.addr())
+            ColorPattern(static_cast<const ColorPattern&>(aPattern));
+        break;
+      case PatternType::LINEAR_GRADIENT:
+        mPattern = new (mLinearGradientPattern.addr()) LinearGradientPattern(
+            static_cast<const LinearGradientPattern&>(aPattern));
+        break;
+      case PatternType::RADIAL_GRADIENT:
+        mPattern = new (mRadialGradientPattern.addr()) RadialGradientPattern(
+            static_cast<const RadialGradientPattern&>(aPattern));
+        break;
+      case PatternType::CONIC_GRADIENT:
+        mPattern = new (mConicGradientPattern.addr()) ConicGradientPattern(
+            static_cast<const ConicGradientPattern&>(aPattern));
+        break;
+      case PatternType::SURFACE:
+        mPattern = new (mSurfacePattern.addr())
+            SurfacePattern(static_cast<const SurfacePattern&>(aPattern));
+        break;
+      default:
+        MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Unknown pattern type");
+    }
+    return mPattern;
+  }
+
+  ColorPattern* InitColorPattern(const DeviceColor& aColor) {
+    MOZ_ASSERT(!mPattern);
+    mPattern = new (mColorPattern.addr()) ColorPattern(aColor);
+    return mColorPattern.addr();
+  }
+
+  LinearGradientPattern* InitLinearGradientPattern(
+      const Point& aBegin, const Point& aEnd,
+      already_AddRefed<GradientStops> aStops,
+      const Matrix& aMatrix = Matrix()) {
+    MOZ_ASSERT(!mPattern);
+    mPattern = new (mLinearGradientPattern.addr())
+        LinearGradientPattern(aBegin, aEnd, std::move(aStops), aMatrix);
+    return mLinearGradientPattern.addr();
+  }
+
+  RadialGradientPattern* InitRadialGradientPattern(
+      const Point& aCenter1, const Point& aCenter2, Float aRadius1,
+      Float aRadius2, already_AddRefed<GradientStops> aStops,
+      const Matrix& aMatrix = Matrix()) {
+    MOZ_ASSERT(!mPattern);
+    mPattern = new (mRadialGradientPattern.addr()) RadialGradientPattern(
+        aCenter1, aCenter2, aRadius1, aRadius2, std::move(aStops), aMatrix);
+    return mRadialGradientPattern.addr();
+  }
+
+  ConicGradientPattern* InitConicGradientPattern(
+      const Point& aCenter, Float aAngle, Float aStartOffset, Float aEndOffset,
+      already_AddRefed<GradientStops> aStops,
+      const Matrix& aMatrix = Matrix()) {
+    MOZ_ASSERT(!mPattern);
+    mPattern = new (mConicGradientPattern.addr()) ConicGradientPattern(
+        aCenter, aAngle, aStartOffset, aEndOffset, std::move(aStops), aMatrix);
+    return mConicGradientPattern.addr();
+  }
+
+  SurfacePattern* InitSurfacePattern(
+      SourceSurface* aSourceSurface, ExtendMode aExtendMode,
+      const Matrix& aMatrix = Matrix(),
+      SamplingFilter aSamplingFilter = SamplingFilter::GOOD,
+      const IntRect& aSamplingRect = IntRect()) {
+    MOZ_ASSERT(!mPattern);
+    mPattern = new (mSurfacePattern.addr()) SurfacePattern(
+        aSourceSurface, aExtendMode, aMatrix, aSamplingFilter, aSamplingRect);
+    return mSurfacePattern.addr();
+  }
+
+  Pattern* GetPattern() { return mPattern; }
+
+  const Pattern* GetPattern() const { return mPattern; }
+
+  operator Pattern&() {
+    if (!mPattern) {
+      MOZ_CRASH("GFX: GeneralPattern not initialized");
+    }
+    return *mPattern;
+  }
+
+ private:
+  union {
+    AlignedStorage2<ColorPattern> mColorPattern;
+    AlignedStorage2<LinearGradientPattern> mLinearGradientPattern;
+    AlignedStorage2<RadialGradientPattern> mRadialGradientPattern;
+    AlignedStorage2<ConicGradientPattern> mConicGradientPattern;
+    AlignedStorage2<SurfacePattern> mSurfacePattern;
+  };
+  Pattern* mPattern = nullptr;
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif  //  _MOZILLA_GFX_PATTERNHELPERS_H