/* -*- 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_2D_H
#define _MOZILLA_GFX_2D_H

#include "Types.h"
#include "Point.h"
#include "Rect.h"
#include "Matrix.h"
#include "Quaternion.h"
#include "UserData.h"
#include "FontVariation.h"
#include <vector>

// GenericRefCountedBase allows us to hold on to refcounted objects of any type
// (contrary to RefCounted<T> which requires knowing the type T) and, in
// particular, without having a dependency on that type. This is used for
// DrawTargetSkia to be able to hold on to a GLContext.
#include "mozilla/GenericRefCounted.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Path.h"

// This RefPtr class isn't ideal for usage in Azure, as it doesn't allow T**
// outparams using the &-operator. But it will have to do as there's no easy
// solution.
#include "mozilla/RefPtr.h"
#include "mozilla/StaticMutex.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/ThreadSafeWeakPtr.h"
#include "mozilla/Atomics.h"

#include "mozilla/DebugOnly.h"

#include "nsRegionFwd.h"

#if defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_GTK)
#  ifndef MOZ_ENABLE_FREETYPE
#    define MOZ_ENABLE_FREETYPE
#  endif
#endif

struct _cairo_surface;
typedef _cairo_surface cairo_surface_t;

struct _cairo_scaled_font;
typedef _cairo_scaled_font cairo_scaled_font_t;

struct FT_LibraryRec_;
typedef FT_LibraryRec_ *FT_Library;

struct FT_FaceRec_;
typedef FT_FaceRec_ *FT_Face;

typedef int FT_Error;

struct ID3D11Texture2D;
struct ID3D11Device;
struct ID2D1Device;
struct ID2D1DeviceContext;
struct IDWriteFactory;
struct IDWriteRenderingParams;
struct IDWriteFontFace;
struct IDWriteFontCollection;

class GrContext;
class SkCanvas;
struct gfxFontStyle;

struct CGContext;
typedef struct CGContext *CGContextRef;

struct CGFont;
typedef CGFont *CGFontRef;

namespace mozilla {

class Mutex;

namespace wr {
struct FontInstanceOptions;
struct FontInstancePlatformOptions;
}  // namespace wr

namespace gfx {
class UnscaledFont;
class ScaledFont;
}  // namespace gfx

namespace gfx {

class AlphaBoxBlur;
class ScaledFont;
class SourceSurface;
class DataSourceSurface;
class DrawTarget;
class DrawEventRecorder;
class FilterNode;
class LogForwarder;

struct NativeSurface {
  NativeSurfaceType mType;
  SurfaceFormat mFormat;
  gfx::IntSize mSize;
  void *mSurface;
};

struct NativeFont {
  NativeFontType mType;
  void *mFont;
};

/**
 * This structure is used to send draw options that are universal to all drawing
 * operations.
 */
struct DrawOptions {
  /// For constructor parameter description, see member data documentation.
  explicit DrawOptions(Float aAlpha = 1.0f,
                       CompositionOp aCompositionOp = CompositionOp::OP_OVER,
                       AntialiasMode aAntialiasMode = AntialiasMode::DEFAULT)
      : mAlpha(aAlpha),
        mCompositionOp(aCompositionOp),
        mAntialiasMode(aAntialiasMode) {}

  Float mAlpha; /**< Alpha value by which the mask generated by this
                     operation is multiplied. */
  CompositionOp mCompositionOp; /**< The operator that indicates how the source
                                   and destination patterns are blended. */
  AntialiasMode mAntialiasMode; /**< The AntiAlias mode used for this drawing
                                     operation. */
};

/**
 * This structure is used to send stroke options that are used in stroking
 * operations.
 */
struct StrokeOptions {
  /// For constructor parameter description, see member data documentation.
  explicit StrokeOptions(Float aLineWidth = 1.0f,
                         JoinStyle aLineJoin = JoinStyle::MITER_OR_BEVEL,
                         CapStyle aLineCap = CapStyle::BUTT,
                         Float aMiterLimit = 10.0f, size_t aDashLength = 0,
                         const Float *aDashPattern = 0, Float aDashOffset = 0.f)
      : mLineWidth(aLineWidth),
        mMiterLimit(aMiterLimit),
        mDashPattern(aDashLength > 0 ? aDashPattern : 0),
        mDashLength(aDashLength),
        mDashOffset(aDashOffset),
        mLineJoin(aLineJoin),
        mLineCap(aLineCap) {
    MOZ_ASSERT(aDashLength == 0 || aDashPattern);
  }

  Float mLineWidth;          //!< Width of the stroke in userspace.
  Float mMiterLimit;         //!< Miter limit in units of linewidth
  const Float *mDashPattern; /**< Series of on/off userspace lengths defining
                                dash. Owned by the caller; must live at least as
                                long as this StrokeOptions.
                                  mDashPattern != null <=> mDashLength > 0. */
  size_t mDashLength;        //!< Number of on/off lengths in mDashPattern.
  Float mDashOffset;         /**< Userspace offset within mDashPattern at which
                                  stroking begins. */
  JoinStyle mLineJoin;       //!< Join style used for joining lines.
  CapStyle mLineCap;         //!< Cap style used for capping lines.
};

/**
 * This structure supplies additional options for calls to DrawSurface.
 */
struct DrawSurfaceOptions {
  /// For constructor parameter description, see member data documentation.
  explicit DrawSurfaceOptions(
      SamplingFilter aSamplingFilter = SamplingFilter::LINEAR,
      SamplingBounds aSamplingBounds = SamplingBounds::UNBOUNDED)
      : mSamplingFilter(aSamplingFilter), mSamplingBounds(aSamplingBounds) {}

  SamplingFilter
      mSamplingFilter; /**< SamplingFilter used when resampling source surface
                            region to the destination region. */
  SamplingBounds mSamplingBounds; /**< This indicates whether the implementation
                                     is allowed to sample pixels outside the
                                     source rectangle as specified in
                                     DrawSurface on the surface. */
};

/**
 * This class is used to store gradient stops, it can only be used with a
 * matching DrawTarget. Not adhering to this condition will make a draw call
 * fail.
 */
class GradientStops : public external::AtomicRefCounted<GradientStops> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(GradientStops)
  virtual ~GradientStops() {}

  virtual BackendType GetBackendType() const = 0;
  virtual bool IsValid() const { return true; }

 protected:
  GradientStops() {}
};

/**
 * This is the base class for 'patterns'. Patterns describe the pixels used as
 * the source for a masked composition operation that is done by the different
 * drawing commands. These objects are not backend specific, however for
 * example the gradient stops on a gradient pattern can be backend specific.
 */
class Pattern {
 public:
  virtual ~Pattern() {}

  virtual PatternType GetType() const = 0;

 protected:
  Pattern() {}
};

class ColorPattern : public Pattern {
 public:
  // Explicit because consumers should generally use ToDeviceColor when
  // creating a ColorPattern.
  explicit ColorPattern(const Color &aColor) : mColor(aColor) {}

  virtual PatternType GetType() const override { return PatternType::COLOR; }

  Color mColor;
};

/**
 * This class is used for Linear Gradient Patterns, the gradient stops are
 * stored in a separate object and are backend dependent. This class itself
 * may be used on the stack.
 */
class LinearGradientPattern : public Pattern {
 public:
  /// For constructor parameter description, see member data documentation.
  LinearGradientPattern(const Point &aBegin, const Point &aEnd,
                        GradientStops *aStops, const Matrix &aMatrix = Matrix())
      : mBegin(aBegin), mEnd(aEnd), mStops(aStops), mMatrix(aMatrix) {}

  virtual PatternType GetType() const override {
    return PatternType::LINEAR_GRADIENT;
  }

  Point mBegin;  //!< Start of the linear gradient
  Point mEnd;    /**< End of the linear gradient - NOTE: In the case
                      of a zero length gradient it will act as the
                      color of the last stop. */
  RefPtr<GradientStops>
      mStops;     /**< GradientStops object for this gradient, this
                       should match the backend type of the draw
                       target this pattern will be used with. */
  Matrix mMatrix; /**< A matrix that transforms the pattern into
                       user space */
};

/**
 * This class is used for Radial Gradient Patterns, the gradient stops are
 * stored in a separate object and are backend dependent. This class itself
 * may be used on the stack.
 */
class RadialGradientPattern : public Pattern {
 public:
  /// For constructor parameter description, see member data documentation.
  RadialGradientPattern(const Point &aCenter1, const Point &aCenter2,
                        Float aRadius1, Float aRadius2, GradientStops *aStops,
                        const Matrix &aMatrix = Matrix())
      : mCenter1(aCenter1),
        mCenter2(aCenter2),
        mRadius1(aRadius1),
        mRadius2(aRadius2),
        mStops(aStops),
        mMatrix(aMatrix) {}

  virtual PatternType GetType() const override {
    return PatternType::RADIAL_GRADIENT;
  }

  Point mCenter1;  //!< Center of the inner (focal) circle.
  Point mCenter2;  //!< Center of the outer circle.
  Float mRadius1;  //!< Radius of the inner (focal) circle.
  Float mRadius2;  //!< Radius of the outer circle.
  RefPtr<GradientStops>
      mStops;      /**< GradientStops object for this gradient, this
                        should match the backend type of the draw target
                        this pattern will be used with. */
  Matrix mMatrix;  //!< A matrix that transforms the pattern into user space
};

/**
 * This class is used for Surface Patterns, they wrap a surface and a
 * repetition mode for the surface. This may be used on the stack.
 */
class SurfacePattern : public Pattern {
 public:
  /// For constructor parameter description, see member data documentation.
  SurfacePattern(SourceSurface *aSourceSurface, ExtendMode aExtendMode,
                 const Matrix &aMatrix = Matrix(),
                 SamplingFilter aSamplingFilter = SamplingFilter::GOOD,
                 const IntRect &aSamplingRect = IntRect())
      : mSurface(aSourceSurface),
        mExtendMode(aExtendMode),
        mSamplingFilter(aSamplingFilter),
        mMatrix(aMatrix),
        mSamplingRect(aSamplingRect) {}

  virtual PatternType GetType() const override { return PatternType::SURFACE; }

  RefPtr<SourceSurface> mSurface;  //!< Surface to use for drawing
  ExtendMode mExtendMode; /**< This determines how the image is extended
                               outside the bounds of the image */
  SamplingFilter
      mSamplingFilter;  //!< Resampling filter for resampling the image.
  Matrix mMatrix;       //!< Transforms the pattern into user space

  IntRect mSamplingRect; /**< Rect that must not be sampled outside of,
                              or an empty rect if none has been
                              specified. */
};

class StoredPattern;
class DrawTargetCaptureImpl;

/**
 * This is the base class for source surfaces. These objects are surfaces
 * which may be used as a source in a SurfacePattern or a DrawSurface call.
 * They cannot be drawn to directly.
 *
 * Although SourceSurface has thread-safe refcount, some SourceSurface cannot
 * be used on random threads at the same time. Only DataSourceSurface can be
 * used on random threads now. This will be fixed in the future. Eventually
 * all SourceSurface should be thread-safe.
 */
class SourceSurface : public external::AtomicRefCounted<SourceSurface> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(SourceSurface)
  virtual ~SourceSurface() {}

  virtual SurfaceType GetType() const = 0;
  virtual IntSize GetSize() const = 0;
  virtual IntRect GetRect() const { return IntRect(IntPoint(0, 0), GetSize()); }
  virtual SurfaceFormat GetFormat() const = 0;

  /** This returns false if some event has made this source surface invalid for
   * usage with current DrawTargets. For example in the case of Direct2D this
   * could return false if we have switched devices since this surface was
   * created.
   */
  virtual bool IsValid() const { return true; }

  /**
   * This returns true if it is the same underlying surface data, even if
   * the objects are different (e.g. indirection due to
   * DataSourceSurfaceWrapper).
   */
  virtual bool Equals(SourceSurface *aOther, bool aSymmetric = true) {
    return this == aOther ||
           (aSymmetric && aOther && aOther->Equals(this, false));
  }

  /**
   * This function will return true if the surface type matches that of a
   * DataSourceSurface and if GetDataSurface will return the same object.
   */
  bool IsDataSourceSurface() const {
    SurfaceType type = GetType();
    return type == SurfaceType::DATA || type == SurfaceType::DATA_SHARED ||
           type == SurfaceType::DATA_RECYCLING_SHARED;
  }

  /**
   * This function will get a DataSourceSurface for this surface, a
   * DataSourceSurface's data can be accessed directly.
   */
  virtual already_AddRefed<DataSourceSurface> GetDataSurface() = 0;

  /** Tries to get this SourceSurface's native surface.  This will fail if aType
   * is not the type of this SourceSurface's native surface.
   */
  virtual void *GetNativeSurface(NativeSurfaceType aType) { return nullptr; }

  void AddUserData(UserDataKey *key, void *userData, void (*destroy)(void *)) {
    mUserData.Add(key, userData, destroy);
  }
  void *GetUserData(UserDataKey *key) const { return mUserData.Get(key); }
  void RemoveUserData(UserDataKey *key) { mUserData.RemoveAndDestroy(key); }

 protected:
  friend class DrawTargetCaptureImpl;
  friend class StoredPattern;

  // This is for internal use, it ensures the SourceSurface's data remains
  // valid during the lifetime of the SourceSurface.
  // @todo XXX - We need something better here :(. But we may be able to get rid
  // of CreateWrappingDataSourceSurface in the future.
  virtual void GuaranteePersistance() {}

  UserData mUserData;
};

class DataSourceSurface : public SourceSurface {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DataSourceSurface, override)
  DataSourceSurface() : mMapCount(0) {}

#ifdef DEBUG
  virtual ~DataSourceSurface() { MOZ_ASSERT(mMapCount == 0); }
#endif

  struct MappedSurface {
    uint8_t *mData;
    int32_t mStride;
  };

  enum MapType { READ, WRITE, READ_WRITE };

  /**
   * This is a scoped version of Map(). Map() is called in the constructor and
   * Unmap() in the destructor. Use this for automatic unmapping of your data
   * surfaces.
   *
   * Use IsMapped() to verify whether Map() succeeded or not.
   */
  class ScopedMap final {
   public:
    explicit ScopedMap(DataSourceSurface *aSurface, MapType aType)
        : mSurface(aSurface), mIsMapped(aSurface->Map(aType, &mMap)) {}

    ScopedMap(ScopedMap &&aOther)
        : mSurface(std::move(aOther.mSurface)),
          mMap(aOther.mMap),
          mIsMapped(aOther.mIsMapped) {
      aOther.mMap.mData = nullptr;
      aOther.mIsMapped = false;
    }

    ScopedMap &operator=(ScopedMap &&aOther) {
      if (mIsMapped) {
        mSurface->Unmap();
      }
      mSurface = std::move(aOther.mSurface);
      mMap = aOther.mMap;
      mIsMapped = aOther.mIsMapped;
      aOther.mMap.mData = nullptr;
      aOther.mIsMapped = false;
      return *this;
    }

    ~ScopedMap() {
      if (mIsMapped) {
        mSurface->Unmap();
      }
    }

    uint8_t *GetData() const {
      MOZ_ASSERT(mIsMapped);
      return mMap.mData;
    }

    int32_t GetStride() const {
      MOZ_ASSERT(mIsMapped);
      return mMap.mStride;
    }

    const MappedSurface *GetMappedSurface() const {
      MOZ_ASSERT(mIsMapped);
      return &mMap;
    }

    bool IsMapped() const { return mIsMapped; }

   private:
    ScopedMap(const ScopedMap &aOther) = delete;
    ScopedMap &operator=(const ScopedMap &aOther) = delete;

    RefPtr<DataSourceSurface> mSurface;
    MappedSurface mMap;
    bool mIsMapped;
  };

  virtual SurfaceType GetType() const override { return SurfaceType::DATA; }
  /** @deprecated
   * Get the raw bitmap data of the surface.
   * Can return null if there was OOM allocating surface data.
   *
   * Deprecated means you shouldn't be using this!! Use Map instead.
   * Please deny any reviews which add calls to this!
   */
  virtual uint8_t *GetData() = 0;

  /** @deprecated
   * Stride of the surface, distance in bytes between the start of the image
   * data belonging to row y and row y+1. This may be negative.
   * Can return 0 if there was OOM allocating surface data.
   */
  virtual int32_t Stride() = 0;

  /**
   * The caller is responsible for ensuring aMappedSurface is not null.
  // Althought Map (and Moz2D in general) isn't normally threadsafe,
  // we want to allow it for SourceSurfaceRawData since it should
  // always be fine (for reading at least).
  //
  // This is the same as the base class implementation except using
  // mMapCount instead of mIsMapped since that breaks for multithread.
  //
  // Once mfbt supports Monitors we should implement proper read/write
  // locking to prevent write races.
   */
  virtual bool Map(MapType, MappedSurface *aMappedSurface) {
    aMappedSurface->mData = GetData();
    aMappedSurface->mStride = Stride();
    bool success = !!aMappedSurface->mData;
    if (success) {
      mMapCount++;
    }
    return success;
  }

  virtual void Unmap() {
    mMapCount--;
    MOZ_ASSERT(mMapCount >= 0);
  }

  /**
   * Returns a DataSourceSurface with the same data as this one, but
   * guaranteed to have surface->GetType() == SurfaceType::DATA.
   *
   * The returning surface might be null, because of OOM or gfx device reset.
   * The caller needs to do null-check before using it.
   */
  virtual already_AddRefed<DataSourceSurface> GetDataSurface() override;

  /**
   * Add the size of the underlying data buffer to the aggregate.
   */
  virtual void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
                                      size_t &aHeapSizeOut,
                                      size_t &aNonHeapSizeOut,
                                      size_t &aExtHandlesOut,
                                      uint64_t &aExtIdOut) const {}

  /**
   * Returns whether or not the data was allocated on the heap. This should
   * be used to determine if the memory needs to be cleared to 0.
   */
  virtual bool OnHeap() const { return true; }

  /**
   * Yields a dirty rect of what has changed since it was last called.
   */
  virtual Maybe<IntRect> TakeDirtyRect() { return Nothing(); }

  /**
   * Indicate a region which has changed in the surface.
   */
  virtual void Invalidate(const IntRect &aDirtyRect) {}

 protected:
  Atomic<int32_t> mMapCount;
};

/** This is an abstract object that accepts path segments. */
class PathSink : public RefCounted<PathSink> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PathSink)
  virtual ~PathSink() {}

  /** Move the current point in the path, any figure currently being drawn will
   * be considered closed during fill operations, however when stroking the
   * closing line segment will not be drawn.
   */
  virtual void MoveTo(const Point &aPoint) = 0;
  /** Add a linesegment to the current figure */
  virtual void LineTo(const Point &aPoint) = 0;
  /** Add a cubic bezier curve to the current figure */
  virtual void BezierTo(const Point &aCP1, const Point &aCP2,
                        const Point &aCP3) = 0;
  /** Add a quadratic bezier curve to the current figure */
  virtual void QuadraticBezierTo(const Point &aCP1, const Point &aCP2) = 0;
  /** Close the current figure, this will essentially generate a line segment
   * from the current point to the starting point for the current figure
   */
  virtual void Close() = 0;
  /** Add an arc to the current figure */
  virtual void Arc(const Point &aOrigin, float aRadius, float aStartAngle,
                   float aEndAngle, bool aAntiClockwise = false) = 0;
  /** Point the current subpath is at - or where the next subpath will start
   * if there is no active subpath.
   */
  virtual Point CurrentPoint() const = 0;
};

class PathBuilder;
class FlattenedPath;

/** The path class is used to create (sets of) figures of any shape that can be
 * filled or stroked to a DrawTarget
 */
class Path : public external::AtomicRefCounted<Path> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(Path)
  virtual ~Path();

  virtual BackendType GetBackendType() const = 0;

  /** This returns a PathBuilder object that contains a copy of the contents of
   * this path and is still writable.
   */
  inline already_AddRefed<PathBuilder> CopyToBuilder() const {
    return CopyToBuilder(GetFillRule());
  }
  inline already_AddRefed<PathBuilder> TransformedCopyToBuilder(
      const Matrix &aTransform) const {
    return TransformedCopyToBuilder(aTransform, GetFillRule());
  }
  /** This returns a PathBuilder object that contains a copy of the contents of
   * this path, converted to use the specified FillRule, and still writable.
   */
  virtual already_AddRefed<PathBuilder> CopyToBuilder(
      FillRule aFillRule) const = 0;
  virtual already_AddRefed<PathBuilder> TransformedCopyToBuilder(
      const Matrix &aTransform, FillRule aFillRule) const = 0;

  /** This function checks if a point lies within a path. It allows passing a
   * transform that will transform the path to the coordinate space in which
   * aPoint is given.
   */
  virtual bool ContainsPoint(const Point &aPoint,
                             const Matrix &aTransform) const = 0;

  /** This function checks if a point lies within the stroke of a path using the
   * specified strokeoptions. It allows passing a transform that will transform
   * the path to the coordinate space in which aPoint is given.
   */
  virtual bool StrokeContainsPoint(const StrokeOptions &aStrokeOptions,
                                   const Point &aPoint,
                                   const Matrix &aTransform) const = 0;

  /** This functions gets the bounds of this path. These bounds are not
   * guaranteed to be tight. A transform may be specified that gives the bounds
   * after application of the transform.
   */
  virtual Rect GetBounds(const Matrix &aTransform = Matrix()) const = 0;

  /** This function gets the bounds of the stroke of this path using the
   * specified strokeoptions. These bounds are not guaranteed to be tight.
   * A transform may be specified that gives the bounds after application of
   * the transform.
   */
  virtual Rect GetStrokedBounds(const StrokeOptions &aStrokeOptions,
                                const Matrix &aTransform = Matrix()) const = 0;

  /** Take the contents of this path and stream it to another sink, this works
   * regardless of the backend that might be used for the destination sink.
   */
  virtual void StreamToSink(PathSink *aSink) const = 0;

  /** This gets the fillrule this path's builder was created with. This is not
   * mutable.
   */
  virtual FillRule GetFillRule() const = 0;

  virtual Float ComputeLength();

  virtual Point ComputePointAtLength(Float aLength, Point *aTangent = nullptr);

 protected:
  Path();
  void EnsureFlattenedPath();

  RefPtr<FlattenedPath> mFlattenedPath;
};

/** The PathBuilder class allows path creation. Once finish is called on the
 * pathbuilder it may no longer be written to.
 */
class PathBuilder : public PathSink {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PathBuilder, override)
  /** Finish writing to the path and return a Path object that can be used for
   * drawing. Future use of the builder results in a crash!
   */
  virtual already_AddRefed<Path> Finish() = 0;

  virtual BackendType GetBackendType() const = 0;
};

struct Glyph {
  uint32_t mIndex;
  Point mPosition;
};

static inline bool operator==(const Glyph &aOne, const Glyph &aOther) {
  return aOne.mIndex == aOther.mIndex && aOne.mPosition == aOther.mPosition;
}

/** This class functions as a glyph buffer that can be drawn to a DrawTarget.
 * @todo XXX - This should probably contain the guts of gfxTextRun in the future
 * as roc suggested. But for now it's a simple container for a glyph vector.
 */
struct GlyphBuffer {
  const Glyph
      *mGlyphs;  //!< A pointer to a buffer of glyphs. Managed by the caller.
  uint32_t mNumGlyphs;  //!< Number of glyphs mGlyphs points to.
};

struct GlyphMetrics {
  // Horizontal distance from the origin to the leftmost side of the bounding
  // box of the drawn glyph. This can be negative!
  Float mXBearing;
  // Horizontal distance from the origin of this glyph to the origin of the
  // next glyph.
  Float mXAdvance;
  // Vertical distance from the origin to the topmost side of the bounding box
  // of the drawn glyph.
  Float mYBearing;
  // Vertical distance from the origin of this glyph to the origin of the next
  // glyph, this is used when drawing vertically and will typically be 0.
  Float mYAdvance;
  // Width of the glyph's black box.
  Float mWidth;
  // Height of the glyph's black box.
  Float mHeight;
};

class UnscaledFont : public SupportsThreadSafeWeakPtr<UnscaledFont> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(UnscaledFont)
  MOZ_DECLARE_THREADSAFEWEAKREFERENCE_TYPENAME(UnscaledFont)

  virtual ~UnscaledFont();

  virtual FontType GetType() const = 0;

  static uint32_t DeletionCounter() { return sDeletionCounter; }

  typedef void (*FontFileDataOutput)(const uint8_t *aData, uint32_t aLength,
                                     uint32_t aIndex, void *aBaton);
  typedef void (*WRFontDescriptorOutput)(const uint8_t *aData, uint32_t aLength,
                                         uint32_t aIndex, void *aBaton);
  typedef void (*FontInstanceDataOutput)(const uint8_t *aData, uint32_t aLength,
                                         void *aBaton);
  typedef void (*FontDescriptorOutput)(const uint8_t *aData, uint32_t aLength,
                                       uint32_t aIndex, void *aBaton);

  virtual bool GetFontFileData(FontFileDataOutput, void *) { return false; }

  virtual bool GetWRFontDescriptor(WRFontDescriptorOutput, void *) {
    return false;
  }

  virtual bool GetFontInstanceData(FontInstanceDataOutput, void *) {
    return false;
  }

  virtual bool GetFontDescriptor(FontDescriptorOutput, void *) { return false; }

  virtual already_AddRefed<ScaledFont> CreateScaledFont(
      Float aGlyphSize, const uint8_t *aInstanceData,
      uint32_t aInstanceDataLength, const FontVariation *aVariations,
      uint32_t aNumVariations) {
    return nullptr;
  }

  virtual already_AddRefed<ScaledFont> CreateScaledFontFromWRFont(
      Float aGlyphSize, const wr::FontInstanceOptions *aOptions,
      const wr::FontInstancePlatformOptions *aPlatformOptions,
      const FontVariation *aVariations, uint32_t aNumVariations) {
    return CreateScaledFont(aGlyphSize, nullptr, 0, aVariations,
                            aNumVariations);
  }

 protected:
  UnscaledFont() {}

 private:
  static Atomic<uint32_t> sDeletionCounter;
};

/** This class is an abstraction of a backend/platform specific font object
 * at a particular size. It is passed into text drawing calls to describe
 * the font used for the drawing call.
 */
class ScaledFont : public SupportsThreadSafeWeakPtr<ScaledFont> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(ScaledFont)
  MOZ_DECLARE_THREADSAFEWEAKREFERENCE_TYPENAME(ScaledFont)

  virtual ~ScaledFont();

  virtual FontType GetType() const = 0;
  virtual Float GetSize() const = 0;
  virtual AntialiasMode GetDefaultAAMode();

  static uint32_t DeletionCounter() { return sDeletionCounter; }

  /** This allows getting a path that describes the outline of a set of glyphs.
   * A target is passed in so that the guarantee is made the returned path
   * can be used with any DrawTarget that has the same backend as the one
   * passed in.
   */
  virtual already_AddRefed<Path> GetPathForGlyphs(
      const GlyphBuffer &aBuffer, const DrawTarget *aTarget) = 0;

  /** This copies the path describing the glyphs into a PathBuilder. We use this
   * API rather than a generic API to append paths because it allows easier
   * implementation in some backends, and more efficient implementation in
   * others.
   */
  virtual void CopyGlyphsToBuilder(const GlyphBuffer &aBuffer,
                                   PathBuilder *aBuilder,
                                   const Matrix *aTransformHint = nullptr) = 0;

  /* This gets the metrics of a set of glyphs for the current font face.
   */
  virtual void GetGlyphDesignMetrics(const uint16_t *aGlyphIndices,
                                     uint32_t aNumGlyphs,
                                     GlyphMetrics *aGlyphMetrics) = 0;

  typedef void (*FontInstanceDataOutput)(const uint8_t *aData, uint32_t aLength,
                                         const FontVariation *aVariations,
                                         uint32_t aNumVariations, void *aBaton);

  virtual bool GetFontInstanceData(FontInstanceDataOutput, void *) {
    return false;
  }

  virtual bool GetWRFontInstanceOptions(
      Maybe<wr::FontInstanceOptions> *aOutOptions,
      Maybe<wr::FontInstancePlatformOptions> *aOutPlatformOptions,
      std::vector<FontVariation> *aOutVariations) {
    return false;
  }

  virtual bool CanSerialize() { return false; }

  virtual bool HasVariationSettings() { return false; }

  void AddUserData(UserDataKey *key, void *userData, void (*destroy)(void *)) {
    mUserData.Add(key, userData, destroy);
  }
  void *GetUserData(UserDataKey *key) { return mUserData.Get(key); }

  void RemoveUserData(UserDataKey *key) { mUserData.RemoveAndDestroy(key); }

  const RefPtr<UnscaledFont> &GetUnscaledFont() const { return mUnscaledFont; }

  virtual cairo_scaled_font_t *GetCairoScaledFont() { return nullptr; }
  virtual void SetCairoScaledFont(cairo_scaled_font_t *font) {}

  Float GetSyntheticObliqueAngle() const { return mSyntheticObliqueAngle; }
  void SetSyntheticObliqueAngle(Float aAngle) {
    mSyntheticObliqueAngle = aAngle;
  }

 protected:
  explicit ScaledFont(const RefPtr<UnscaledFont> &aUnscaledFont)
      : mUnscaledFont(aUnscaledFont), mSyntheticObliqueAngle(0.0f) {}

  UserData mUserData;
  RefPtr<UnscaledFont> mUnscaledFont;
  Float mSyntheticObliqueAngle;

 private:
  static Atomic<uint32_t> sDeletionCounter;
};

/**
 * Derived classes hold a native font resource from which to create
 * ScaledFonts.
 */
class NativeFontResource
    : public external::AtomicRefCounted<NativeFontResource> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(NativeFontResource)

  /**
   * Creates a UnscaledFont using the font corresponding to the index.
   *
   * @param aIndex index for the font within the resource.
   * @param aInstanceData pointer to read-only buffer of any available instance
   *                      data.
   * @param aInstanceDataLength the size of the instance data.
   * @return an already_addrefed UnscaledFont, containing nullptr if failed.
   */
  virtual already_AddRefed<UnscaledFont> CreateUnscaledFont(
      uint32_t aIndex, const uint8_t *aInstanceData,
      uint32_t aInstanceDataLength) = 0;

  virtual ~NativeFontResource() {}
};

class DrawTargetCapture;

/** This is the main class used for all the drawing. It is created through the
 * factory and accepts drawing commands. The results of drawing to a target
 * may be used either through a Snapshot or by flushing the target and directly
 * accessing the backing store a DrawTarget was created with.
 */
class DrawTarget : public external::AtomicRefCounted<DrawTarget> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DrawTarget)
  DrawTarget()
      : mTransformDirty(false),
        mPermitSubpixelAA(false),
        mFormat(SurfaceFormat::UNKNOWN) {}
  virtual ~DrawTarget() {}

  virtual bool IsValid() const { return true; };
  virtual DrawTargetType GetType() const = 0;

  virtual BackendType GetBackendType() const = 0;

  virtual bool IsRecording() const { return false; }
  virtual bool IsCaptureDT() const { return false; }

  /**
   * Returns a SourceSurface which is a snapshot of the current contents of the
   * DrawTarget. Multiple calls to Snapshot() without any drawing operations in
   * between will normally return the same SourceSurface object.
   */
  virtual already_AddRefed<SourceSurface> Snapshot() = 0;

  // Snapshots the contents and returns an alpha mask
  // based on the RGB values.
  virtual already_AddRefed<SourceSurface> IntoLuminanceSource(
      LuminanceType aLuminanceType, float aOpacity);
  virtual IntSize GetSize() const = 0;
  virtual IntRect GetRect() const { return IntRect(IntPoint(0, 0), GetSize()); }

  /**
   * If possible returns the bits to this DrawTarget for direct manipulation.
   * While the bits is locked any modifications to this DrawTarget is forbidden.
   * Release takes the original data pointer for safety.
   */
  virtual bool LockBits(uint8_t **aData, IntSize *aSize, int32_t *aStride,
                        SurfaceFormat *aFormat, IntPoint *aOrigin = nullptr) {
    return false;
  }
  virtual void ReleaseBits(uint8_t *aData) {}

  /** Ensure that the DrawTarget backend has flushed all drawing operations to
   * this draw target. This must be called before using the backing surface of
   * this draw target outside of GFX 2D code.
   */
  virtual void Flush() = 0;

  /**
   * Realize a DrawTargetCapture onto the draw target.
   *
   * @param aSource Capture DrawTarget to draw
   * @param aTransform Transform to apply when replaying commands
   */
  virtual void DrawCapturedDT(DrawTargetCapture *aCaptureDT,
                              const Matrix &aTransform);

  /**
   * Draw a surface to the draw target. Possibly doing partial drawing or
   * applying scaling. No sampling happens outside the source.
   *
   * @param aSurface Source surface to draw
   * @param aDest Destination rectangle that this drawing operation should draw
   *              to
   * @param aSource Source rectangle in aSurface coordinates, this area of
   *                aSurface
   *                will be stretched to the size of aDest.
   * @param aOptions General draw options that are applied to the operation
   * @param aSurfOptions DrawSurface options that are applied
   */
  virtual void DrawSurface(
      SourceSurface *aSurface, const Rect &aDest, const Rect &aSource,
      const DrawSurfaceOptions &aSurfOptions = DrawSurfaceOptions(),
      const DrawOptions &aOptions = DrawOptions()) = 0;

  virtual void DrawDependentSurface(
      uint64_t aId, const Rect &aDest,
      const DrawSurfaceOptions &aSurfOptions = DrawSurfaceOptions(),
      const DrawOptions &aOptions = DrawOptions()) {
    MOZ_CRASH("GFX: DrawDependentSurface");
  }

  /**
   * Draw the output of a FilterNode to the DrawTarget.
   *
   * @param aNode FilterNode to draw
   * @param aSourceRect Source rectangle in FilterNode space to draw
   * @param aDestPoint Destination point on the DrawTarget to draw the
   *                   SourceRectangle of the filter output to
   */
  virtual void DrawFilter(FilterNode *aNode, const Rect &aSourceRect,
                          const Point &aDestPoint,
                          const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Blend a surface to the draw target with a shadow. The shadow is drawn as a
   * gaussian blur using a specified sigma. The shadow is clipped to the size
   * of the input surface, so the input surface should contain a transparent
   * border the size of the approximate coverage of the blur (3 * aSigma).
   * NOTE: This function works in device space!
   *
   * @param aSurface Source surface to draw.
   * @param aDest Destination point that this drawing operation should draw to.
   * @param aColor Color of the drawn shadow
   * @param aOffset Offset of the shadow
   * @param aSigma Sigma used for the guassian filter kernel
   * @param aOperator Composition operator used
   */
  virtual void DrawSurfaceWithShadow(SourceSurface *aSurface,
                                     const Point &aDest, const Color &aColor,
                                     const Point &aOffset, Float aSigma,
                                     CompositionOp aOperator) = 0;

  /**
   * Clear a rectangle on the draw target to transparent black. This will
   * respect the clipping region and transform.
   *
   * @param aRect Rectangle to clear
   */
  virtual void ClearRect(const Rect &aRect) = 0;

  /**
   * This is essentially a 'memcpy' between two surfaces. It moves a pixel
   * aligned area from the source surface unscaled directly onto the
   * drawtarget. This ignores both transform and clip.
   *
   * @param aSurface Surface to copy from
   * @param aSourceRect Source rectangle to be copied
   * @param aDest Destination point to copy the surface to
   */
  virtual void CopySurface(SourceSurface *aSurface, const IntRect &aSourceRect,
                           const IntPoint &aDestination) = 0;

  /** @see CopySurface
   * Same as CopySurface, except uses itself as the source.
   *
   * Some backends may be able to optimize this better
   * than just taking a snapshot and using CopySurface.
   */
  virtual void CopyRect(const IntRect &aSourceRect,
                        const IntPoint &aDestination) {
    RefPtr<SourceSurface> source = Snapshot();
    CopySurface(source, aSourceRect, aDestination);
  }

  /**
   * Fill a rectangle on the DrawTarget with a certain source pattern.
   *
   * @param aRect Rectangle that forms the mask of this filling operation
   * @param aPattern Pattern that forms the source of this filling operation
   * @param aOptions Options that are applied to this operation
   */
  virtual void FillRect(const Rect &aRect, const Pattern &aPattern,
                        const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Fill a rounded rectangle on the DrawTarget with a certain source pattern.
   *
   * @param aRect Rounded rectangle that forms the mask of this filling
   * operation
   * @param aPattern Pattern that forms the source of this filling operation
   * @param aOptions Options that are applied to this operation
   */
  virtual void FillRoundedRect(const RoundedRect &aRect,
                               const Pattern &aPattern,
                               const DrawOptions &aOptions = DrawOptions());

  /**
   * Stroke a rectangle on the DrawTarget with a certain source pattern.
   *
   * @param aRect Rectangle that forms the mask of this stroking operation
   * @param aPattern Pattern that forms the source of this stroking operation
   * @param aOptions Options that are applied to this operation
   */
  virtual void StrokeRect(const Rect &aRect, const Pattern &aPattern,
                          const StrokeOptions &aStrokeOptions = StrokeOptions(),
                          const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Stroke a line on the DrawTarget with a certain source pattern.
   *
   * @param aStart Starting point of the line
   * @param aEnd End point of the line
   * @param aPattern Pattern that forms the source of this stroking operation
   * @param aOptions Options that are applied to this operation
   */
  virtual void StrokeLine(const Point &aStart, const Point &aEnd,
                          const Pattern &aPattern,
                          const StrokeOptions &aStrokeOptions = StrokeOptions(),
                          const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Stroke a path on the draw target with a certain source pattern.
   *
   * @param aPath Path that is to be stroked
   * @param aPattern Pattern that should be used for the stroke
   * @param aStrokeOptions Stroke options used for this operation
   * @param aOptions Draw options used for this operation
   */
  virtual void Stroke(const Path *aPath, const Pattern &aPattern,
                      const StrokeOptions &aStrokeOptions = StrokeOptions(),
                      const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Fill a path on the draw target with a certain source pattern.
   *
   * @param aPath Path that is to be filled
   * @param aPattern Pattern that should be used for the fill
   * @param aOptions Draw options used for this operation
   */
  virtual void Fill(const Path *aPath, const Pattern &aPattern,
                    const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Fill a series of glyphs on the draw target with a certain source pattern.
   */
  virtual void FillGlyphs(ScaledFont *aFont, const GlyphBuffer &aBuffer,
                          const Pattern &aPattern,
                          const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Stroke a series of glyphs on the draw target with a certain source pattern.
   */
  virtual void StrokeGlyphs(
      ScaledFont *aFont, const GlyphBuffer &aBuffer, const Pattern &aPattern,
      const StrokeOptions &aStrokeOptions = StrokeOptions(),
      const DrawOptions &aOptions = DrawOptions());

  /**
   * This takes a source pattern and a mask, and composites the source pattern
   * onto the destination surface using the alpha channel of the mask pattern
   * as a mask for the operation.
   *
   * @param aSource Source pattern
   * @param aMask Mask pattern
   * @param aOptions Drawing options
   */
  virtual void Mask(const Pattern &aSource, const Pattern &aMask,
                    const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * This takes a source pattern and a mask, and composites the source pattern
   * onto the destination surface using the alpha channel of the mask source.
   * The operation is bound by the extents of the mask.
   *
   * @param aSource Source pattern
   * @param aMask Mask surface
   * @param aOffset a transformed offset that the surface is masked at
   * @param aOptions Drawing options
   */
  virtual void MaskSurface(const Pattern &aSource, SourceSurface *aMask,
                           Point aOffset,
                           const DrawOptions &aOptions = DrawOptions()) = 0;

  /**
   * Draw aSurface using the 3D transform aMatrix. The DrawTarget's transform
   * and clip are applied after the 3D transform.
   *
   * If the transform fails (i.e. because aMatrix is singular), false is
   * returned and nothing is drawn.
   */
  virtual bool Draw3DTransformedSurface(SourceSurface *aSurface,
                                        const Matrix4x4 &aMatrix);

  /**
   * Push a clip to the DrawTarget.
   *
   * @param aPath The path to clip to
   */
  virtual void PushClip(const Path *aPath) = 0;

  /**
   * Push an axis-aligned rectangular clip to the DrawTarget. This rectangle
   * is specified in user space.
   *
   * @param aRect The rect to clip to
   */
  virtual void PushClipRect(const Rect &aRect) = 0;

  /**
   * Push a clip region specifed by the union of axis-aligned rectangular
   * clips to the DrawTarget. These rectangles are specified in device space.
   * This must be balanced by a corresponding call to PopClip within a layer.
   *
   * @param aRects The rects to clip to
   * @param aCount The number of rectangles
   */
  virtual void PushDeviceSpaceClipRects(const IntRect *aRects, uint32_t aCount);

  /** Pop a clip from the DrawTarget. A pop without a corresponding push will
   * be ignored.
   */
  virtual void PopClip() = 0;

  /**
   * Push a 'layer' to the DrawTarget, a layer is a temporary surface that all
   * drawing will be redirected to, this is used for example to support group
   * opacity or the masking of groups. Clips must be balanced within a layer,
   * i.e. between a matching PushLayer/PopLayer pair there must be as many
   * PushClip(Rect) calls as there are PopClip calls.
   *
   * @param aOpaque Whether the layer will be opaque
   * @param aOpacity Opacity of the layer
   * @param aMask Mask applied to the layer
   * @param aMaskTransform Transform applied to the layer mask
   * @param aBounds Optional bounds in device space to which the layer is
   *                limited in size.
   * @param aCopyBackground Whether to copy the background into the layer, this
   *                        is only supported when aOpaque is true.
   */
  virtual void PushLayer(bool aOpaque, Float aOpacity, SourceSurface *aMask,
                         const Matrix &aMaskTransform,
                         const IntRect &aBounds = IntRect(),
                         bool aCopyBackground = false) {
    MOZ_CRASH("GFX: PushLayer");
  }

  /**
   * Push a 'layer' to the DrawTarget, a layer is a temporary surface that all
   * drawing will be redirected to, this is used for example to support group
   * opacity or the masking of groups. Clips must be balanced within a layer,
   * i.e. between a matching PushLayer/PopLayer pair there must be as many
   * PushClip(Rect) calls as there are PopClip calls.
   *
   * @param aOpaque Whether the layer will be opaque
   * @param aOpacity Opacity of the layer
   * @param aMask Mask applied to the layer
   * @param aMaskTransform Transform applied to the layer mask
   * @param aBounds Optional bounds in device space to which the layer is
   *                limited in size.
   * @param aCopyBackground Whether to copy the background into the layer, this
   *                        is only supported when aOpaque is true.
   */
  virtual void PushLayerWithBlend(bool aOpaque, Float aOpacity,
                                  SourceSurface *aMask,
                                  const Matrix &aMaskTransform,
                                  const IntRect &aBounds = IntRect(),
                                  bool aCopyBackground = false,
                                  CompositionOp = CompositionOp::OP_OVER) {
    MOZ_CRASH("GFX: PushLayerWithBlend");
  }

  /**
   * This balances a call to PushLayer and proceeds to blend the layer back
   * onto the background. This blend will blend the temporary surface back
   * onto the target in device space using POINT sampling and operator over.
   */
  virtual void PopLayer() { MOZ_CRASH("GFX: PopLayer"); }

  /**
   * Perform an in-place blur operation. This is only supported on data draw
   * targets.
   */
  virtual void Blur(const AlphaBoxBlur &aBlur);

  /**
   * Performs an in-place edge padding operation.
   * aRegion is specified in device space.
   */
  virtual void PadEdges(const IntRegion &aRegion);

  /**
   * Performs an in-place buffer unrotation operation.
   */
  virtual bool Unrotate(IntPoint aRotation);

  /**
   * Create a SourceSurface optimized for use with this DrawTarget from
   * existing bitmap data in memory.
   *
   * The SourceSurface does not take ownership of aData, and may be freed at any
   * time.
   */
  virtual already_AddRefed<SourceSurface> CreateSourceSurfaceFromData(
      unsigned char *aData, const IntSize &aSize, int32_t aStride,
      SurfaceFormat aFormat) const = 0;

  /**
   * Create a SourceSurface optimized for use with this DrawTarget from an
   * arbitrary SourceSurface type supported by this backend. This may return
   * aSourceSurface or some other existing surface.
   */
  virtual already_AddRefed<SourceSurface> OptimizeSourceSurface(
      SourceSurface *aSurface) const = 0;
  virtual already_AddRefed<SourceSurface> OptimizeSourceSurfaceForUnknownAlpha(
      SourceSurface *aSurface) const {
    return OptimizeSourceSurface(aSurface);
  }

  /**
   * Create a SourceSurface for a type of NativeSurface. This may fail if the
   * draw target does not know how to deal with the type of NativeSurface passed
   * in. If this succeeds, the SourceSurface takes the ownersip of the
   * NativeSurface.
   */
  virtual already_AddRefed<SourceSurface> CreateSourceSurfaceFromNativeSurface(
      const NativeSurface &aSurface) const = 0;

  /**
   * Create a DrawTarget whose snapshot is optimized for use with this
   * DrawTarget.
   */
  virtual already_AddRefed<DrawTarget> CreateSimilarDrawTarget(
      const IntSize &aSize, SurfaceFormat aFormat) const = 0;

  /**
   * Returns false if CreateSimilarDrawTarget would return null with the same
   * parameters. May return true even in cases where CreateSimilarDrawTarget
   * return null (i.e. this function returning false has meaning, but returning
   * true doesn't guarantee anything).
   */
  virtual bool CanCreateSimilarDrawTarget(const IntSize &aSize,
                                          SurfaceFormat aFormat) const {
    return true;
  }

  /**
   * Create a draw target optimized for drawing a shadow.
   *
   * Note that aSigma is the blur radius that must be used when we draw the
   * shadow. Also note that this doesn't affect the size of the allocated
   * surface, the caller is still responsible for including the shadow area in
   * its size.
   */
  virtual already_AddRefed<DrawTarget> CreateShadowDrawTarget(
      const IntSize &aSize, SurfaceFormat aFormat, float aSigma) const {
    return CreateSimilarDrawTarget(aSize, aFormat);
  }

  /**
   * Create a similar DrawTarget whose requested size may be clipped based
   * on this DrawTarget's rect transformed to the new target's space.
   */
  virtual RefPtr<DrawTarget> CreateClippedDrawTarget(
      const IntSize &aMaxSize, const Matrix &aTransform,
      SurfaceFormat aFormat) const {
    return CreateSimilarDrawTarget(aMaxSize, aFormat);
  }

  /**
   * Create a similar draw target, but if the draw target is not backed by a
   * raster backend (for example, it is capturing or recording), force it to
   * create a raster target instead. This is intended for code that wants to
   * cache pixels, and would have no effect if it were caching a recording.
   */
  virtual RefPtr<DrawTarget> CreateSimilarRasterTarget(
      const IntSize &aSize, SurfaceFormat aFormat) const {
    return CreateSimilarDrawTarget(aSize, aFormat);
  }

  /**
   * Create a path builder with the specified fillmode.
   *
   * We need the fill mode up front because of Direct2D.
   * ID2D1SimplifiedGeometrySink requires the fill mode
   * to be set before calling BeginFigure().
   */
  virtual already_AddRefed<PathBuilder> CreatePathBuilder(
      FillRule aFillRule = FillRule::FILL_WINDING) const = 0;

  /**
   * Create a GradientStops object that holds information about a set of
   * gradient stops, this object is required for linear or radial gradient
   * patterns to represent the color stops in the gradient.
   *
   * @param aStops An array of gradient stops
   * @param aNumStops Number of stops in the array aStops
   * @param aExtendNone This describes how to extend the stop color outside of
   * the gradient area.
   */
  virtual already_AddRefed<GradientStops> CreateGradientStops(
      GradientStop *aStops, uint32_t aNumStops,
      ExtendMode aExtendMode = ExtendMode::CLAMP) const = 0;

  /**
   * Create a FilterNode object that can be used to apply a filter to various
   * inputs.
   *
   * @param aType Type of filter node to be created.
   */
  virtual already_AddRefed<FilterNode> CreateFilter(FilterType aType) = 0;

  Matrix GetTransform() const { return mTransform; }

  /*
   * Get the metrics of a glyph, including any additional spacing that is taken
   * during rasterization to this backends (for example because of antialiasing
   * filters.
   *
   * aScaledFont The scaled font used when drawing.
   * aGlyphIndices An array of indices for the glyphs whose the metrics are
   *               wanted
   * aNumGlyphs The amount of elements in aGlyphIndices
   * aGlyphMetrics The glyph metrics
   */
  virtual void GetGlyphRasterizationMetrics(ScaledFont *aScaledFont,
                                            const uint16_t *aGlyphIndices,
                                            uint32_t aNumGlyphs,
                                            GlyphMetrics *aGlyphMetrics) {
    aScaledFont->GetGlyphDesignMetrics(aGlyphIndices, aNumGlyphs,
                                       aGlyphMetrics);
  }

  /**
   * Set a transform on the surface, this transform is applied at drawing time
   * to both the mask and source of the operation.
   *
   * Performance note: For some backends it is expensive to change the current
   * transform (because transforms affect a lot of the parts of the pipeline,
   * so new transform change can result in a pipeline flush).  To get around
   * this, DrawTarget implementations buffer transform changes and try to only
   * set the current transform on the backend when required.  That tracking has
   * its own performance impact though, and ideally callers would be smart
   * enough not to require it.  At a future date this method may stop this
   * doing transform buffering so, if you're a consumer, please try to be smart
   * about calling this method as little as possible.  For example, instead of
   * concatenating a translation onto the current transform then calling
   * FillRect, try to integrate the translation into FillRect's aRect
   * argument's x/y offset.
   */
  virtual void SetTransform(const Matrix &aTransform) {
    mTransform = aTransform;
    mTransformDirty = true;
  }

  inline void ConcatTransform(const Matrix &aTransform) {
    SetTransform(aTransform * Matrix(GetTransform()));
  }

  SurfaceFormat GetFormat() const { return mFormat; }

  /** Tries to get a native surface for a DrawTarget, this may fail if the
   * draw target cannot convert to this surface type.
   */
  virtual void *GetNativeSurface(NativeSurfaceType aType) { return nullptr; }

  virtual bool IsDualDrawTarget() const { return false; }
  virtual bool IsTiledDrawTarget() const { return false; }
  virtual bool SupportsRegionClipping() const { return true; }

  void AddUserData(UserDataKey *key, void *userData, void (*destroy)(void *)) {
    mUserData.Add(key, userData, destroy);
  }
  void *GetUserData(UserDataKey *key) const { return mUserData.Get(key); }
  void *RemoveUserData(UserDataKey *key) { return mUserData.Remove(key); }

  /** Within this rectangle all pixels will be opaque by the time the result of
   * this DrawTarget is first used for drawing. Either by the underlying surface
   * being used as an input to external drawing, or Snapshot() being called.
   * This rectangle is specified in device space.
   */
  void SetOpaqueRect(const IntRect &aRect) { mOpaqueRect = aRect; }

  const IntRect &GetOpaqueRect() const { return mOpaqueRect; }

  virtual bool IsCurrentGroupOpaque() {
    return GetFormat() == SurfaceFormat::B8G8R8X8;
  }

  virtual void SetPermitSubpixelAA(bool aPermitSubpixelAA) {
    mPermitSubpixelAA = aPermitSubpixelAA;
  }

  bool GetPermitSubpixelAA() { return mPermitSubpixelAA; }

  /**
   * Mark the end of an Item in a DrawTargetRecording. These markers
   * are used for merging recordings together.
   *
   * This should only be called on the 'root' DrawTargetRecording.
   * Calling it on a child DrawTargetRecordings will cause confusion.
   *
   * Note: this is a bit of a hack. It might be better to just recreate
   * the DrawTargetRecording.
   */
  virtual void FlushItem(const IntRect &aBounds) {}

  /**
   * Ensures that no snapshot is still pointing to this DrawTarget's surface
   * data.
   *
   * This can be useful if the DrawTarget is wrapped around data that it does
   * not own, and for some reason the owner of the data has to make it
   * temporarily unavailable without the DrawTarget knowing about it. This can
   * cause costly surface copies, so it should not be used without a a good
   * reason.
   */
  virtual void DetachAllSnapshots() = 0;

#ifdef USE_SKIA_GPU
  virtual bool InitWithGrContext(GrContext *aGrContext, const IntSize &aSize,
                                 SurfaceFormat aFormat) {
    MOZ_CRASH("GFX: InitWithGrContext");
  }
#endif

 protected:
  UserData mUserData;
  Matrix mTransform;
  IntRect mOpaqueRect;
  bool mTransformDirty : 1;
  bool mPermitSubpixelAA : 1;

  SurfaceFormat mFormat;
};

class DrawTargetCapture : public DrawTarget {
 public:
  virtual bool IsCaptureDT() const override { return true; }

  virtual bool IsEmpty() const = 0;
  virtual void Dump() = 0;
};

class DrawEventRecorder : public RefCounted<DrawEventRecorder> {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DrawEventRecorder)
  // returns true if there were any items in the recording
  virtual bool Finish() = 0;
  virtual ~DrawEventRecorder() {}
};

struct Tile {
  RefPtr<DrawTarget> mDrawTarget;
  IntPoint mTileOrigin;
};

struct TileSet {
  Tile *mTiles;
  size_t mTileCount;
};

struct Config {
  LogForwarder *mLogForwarder;
  int32_t mMaxTextureSize;
  int32_t mMaxAllocSize;

  Config()
      : mLogForwarder(nullptr),
        mMaxTextureSize(8192),
        mMaxAllocSize(52000000) {}
};

class GFX2D_API Factory {
  using char_type = filesystem::Path::value_type;

 public:
  static void Init(const Config &aConfig);
  static void ShutDown();

  static bool HasSSE2();
  static bool HasSSE4();

  /**
   * Returns false if any of the following are true:
   *
   *   - the width/height of |sz| are less than or equal to zero
   *   - the width/height of |sz| are greater than |limit|
   *   - the number of bytes that need to be allocated for the surface is too
   *     big to fit in an int32_t, or bigger than |allocLimit|, if specifed
   *
   * To calculate the number of bytes that need to be allocated for the surface
   * this function makes the conservative assumption that there need to be
   * 4 bytes-per-pixel, and the stride alignment is 16 bytes.
   *
   * The reason for using int32_t rather than uint32_t is again to be
   * conservative; some code has in the past and may in the future use signed
   * integers to store buffer lengths etc.
   */
  static bool CheckSurfaceSize(const IntSize &sz, int32_t limit = 0,
                               int32_t allocLimit = 0);

  /**
   * Make sure that the given buffer size doesn't exceed the allocation limit.
   */
  static bool CheckBufferSize(int32_t bufSize);

  /** Make sure the given dimension satisfies the CheckSurfaceSize and is
   * within 8k limit.  The 8k value is chosen a bit randomly.
   */
  static bool ReasonableSurfaceSize(const IntSize &aSize);

  static bool AllowedSurfaceSize(const IntSize &aSize);

  static already_AddRefed<DrawTarget> CreateDrawTargetForCairoSurface(
      cairo_surface_t *aSurface, const IntSize &aSize,
      SurfaceFormat *aFormat = nullptr);

  static already_AddRefed<SourceSurface> CreateSourceSurfaceForCairoSurface(
      cairo_surface_t *aSurface, const IntSize &aSize, SurfaceFormat aFormat);

  static already_AddRefed<DrawTarget> CreateDrawTarget(BackendType aBackend,
                                                       const IntSize &aSize,
                                                       SurfaceFormat aFormat);

  /**
   * Create a DrawTarget that captures the drawing commands to eventually be
   * replayed onto the DrawTarget provided. An optional byte size can be
   * provided as a limit for the CaptureCommandList. When the limit is reached,
   * the CaptureCommandList will be replayed to the target and then cleared.
   *
   * @param aSize Size of the area this DT will capture.
   * @param aFlushBytes The byte limit at which to flush the CaptureCommandList
   */
  static already_AddRefed<DrawTargetCapture> CreateCaptureDrawTargetForTarget(
      gfx::DrawTarget *aTarget, size_t aFlushBytes = 0);

  /**
   * Create a DrawTarget that captures the drawing commands and can be replayed
   * onto a compatible DrawTarget afterwards.
   *
   * @param aSize Size of the area this DT will capture.
   */
  static already_AddRefed<DrawTargetCapture> CreateCaptureDrawTarget(
      BackendType aBackend, const IntSize &aSize, SurfaceFormat aFormat);

  static already_AddRefed<DrawTargetCapture> CreateCaptureDrawTargetForData(
      BackendType aBackend, const IntSize &aSize, SurfaceFormat aFormat,
      int32_t aStride, size_t aSurfaceAllocationSize);

  static already_AddRefed<DrawTarget> CreateWrapAndRecordDrawTarget(
      DrawEventRecorder *aRecorder, DrawTarget *aDT);

  static already_AddRefed<DrawTarget> CreateRecordingDrawTarget(
      DrawEventRecorder *aRecorder, DrawTarget *aDT, IntSize aSize);

  static already_AddRefed<DrawTarget> CreateDrawTargetForData(
      BackendType aBackend, unsigned char *aData, const IntSize &aSize,
      int32_t aStride, SurfaceFormat aFormat, bool aUninitialized = false);

#ifdef XP_DARWIN
  static already_AddRefed<ScaledFont> CreateScaledFontForMacFont(
      CGFontRef aCGFont, const RefPtr<UnscaledFont> &aUnscaledFont, Float aSize,
      const Color &aFontSmoothingBackgroundColor, bool aUseFontSmoothing = true,
      bool aApplySyntheticBold = false);
#endif

  /**
   * This creates a NativeFontResource from TrueType data.
   *
   * @param aData Pointer to the data
   * @param aSize Size of the TrueType data
   * @param aBackendType Type of the reference DrawTarget the font should be
   *                     created for.
   * @param aFontType Type of NativeFontResource that should be created.
   * @param aFontContext Optional native font context to be used to create the
   *                              NativeFontResource.
   * @return a NativeFontResource of nullptr if failed.
   */
  static already_AddRefed<NativeFontResource> CreateNativeFontResource(
      uint8_t *aData, uint32_t aSize, BackendType aBackendType,
      FontType aFontType, void *aFontContext = nullptr);

  /**
   * This creates an unscaled font of the given type based on font descriptor
   * data retrieved from ScaledFont::GetFontDescriptor.
   */
  static already_AddRefed<UnscaledFont> CreateUnscaledFontFromFontDescriptor(
      FontType aType, const uint8_t *aData, uint32_t aDataLength,
      uint32_t aIndex);

  /**
   * Creates a ScaledFont from the supplied NativeFont.
   *
   * If aScaledFont is supplied, this creates a scaled font with an associated
   * cairo_scaled_font_t. The NativeFont and cairo_scaled_font_t* parameters
   * must correspond to the same font.
   */
  static already_AddRefed<ScaledFont> CreateScaledFontForNativeFont(
      const NativeFont &aNativeFont, const RefPtr<UnscaledFont> &aUnscaledFont,
      Float aSize, cairo_scaled_font_t *aScaledFont = nullptr);

  /**
   * This creates a simple data source surface for a certain size. It allocates
   * new memory for the surface. This memory is freed when the surface is
   * destroyed.  The caller is responsible for handing the case where nullptr
   * is returned. The surface is not zeroed unless requested.
   */
  static already_AddRefed<DataSourceSurface> CreateDataSourceSurface(
      const IntSize &aSize, SurfaceFormat aFormat, bool aZero = false);

  /**
   * This creates a simple data source surface for a certain size with a
   * specific stride, which must be large enough to fit all pixels.
   * It allocates new memory for the surface. This memory is freed when
   * the surface is destroyed.  The caller is responsible for handling the case
   * where nullptr is returned. The surface is not zeroed unless requested.
   */
  static already_AddRefed<DataSourceSurface> CreateDataSourceSurfaceWithStride(
      const IntSize &aSize, SurfaceFormat aFormat, int32_t aStride,
      bool aZero = false);

  typedef void (*SourceSurfaceDeallocator)(void *aClosure);

  /**
   * This creates a simple data source surface for some existing data. It will
   * wrap this data and the data for this source surface.
   *
   * We can provide a custom destroying function for |aData|. This will be
   * called in the surface dtor using |aDeallocator| and the |aClosure|. If
   * there are errors during construction(return a nullptr surface), the caller
   * is responsible for the deallocation.
   *
   * If there is no destroying function, the caller is responsible for
   * deallocating the aData memory only after destruction of this
   * DataSourceSurface.
   */
  static already_AddRefed<DataSourceSurface> CreateWrappingDataSourceSurface(
      uint8_t *aData, int32_t aStride, const IntSize &aSize,
      SurfaceFormat aFormat, SourceSurfaceDeallocator aDeallocator = nullptr,
      void *aClosure = nullptr);

  static void CopyDataSourceSurface(DataSourceSurface *aSource,
                                    DataSourceSurface *aDest);

  static already_AddRefed<DrawEventRecorder> CreateEventRecorderForFile(
      const char_type *aFilename);

  static void SetGlobalEventRecorder(DrawEventRecorder *aRecorder);

  static uint32_t GetMaxSurfaceSize(BackendType aType);

  static LogForwarder *GetLogForwarder() {
    return sConfig ? sConfig->mLogForwarder : nullptr;
  }

 private:
  static Config *sConfig;

 public:
#ifdef USE_SKIA_GPU
  static already_AddRefed<DrawTarget> CreateDrawTargetSkiaWithGrContext(
      GrContext *aGrContext, const IntSize &aSize, SurfaceFormat aFormat);
#endif

  static void PurgeAllCaches();

  static already_AddRefed<DrawTarget> CreateDualDrawTarget(DrawTarget *targetA,
                                                           DrawTarget *targetB);

  static already_AddRefed<SourceSurface> CreateDualSourceSurface(
      SourceSurface *sourceA, SourceSurface *sourceB);

  /*
   * This creates a new tiled DrawTarget. When a tiled drawtarget is used the
   * drawing is distributed over number of tiles which may each hold an
   * individual offset. The tiles in the set must each have the same backend
   * and format.
   */
  static already_AddRefed<DrawTarget> CreateTiledDrawTarget(
      const TileSet &aTileSet);
  static already_AddRefed<DrawTarget> CreateOffsetDrawTarget(
      DrawTarget *aDrawTarget, IntPoint aTileOrigin);

  static bool DoesBackendSupportDataDrawtarget(BackendType aType);

#ifdef USE_SKIA
  static already_AddRefed<DrawTarget> CreateDrawTargetWithSkCanvas(
      SkCanvas *aCanvas);
#endif

#ifdef MOZ_ENABLE_FREETYPE
  static void SetFTLibrary(FT_Library aFTLibrary);
  static FT_Library GetFTLibrary();

  static FT_Library NewFTLibrary();
  static void ReleaseFTLibrary(FT_Library aFTLibrary);
  static void LockFTLibrary(FT_Library aFTLibrary);
  static void UnlockFTLibrary(FT_Library aFTLibrary);

  static FT_Face NewFTFace(FT_Library aFTLibrary, const char *aFileName,
                           int aFaceIndex);
  static FT_Face NewFTFaceFromData(FT_Library aFTLibrary, const uint8_t *aData,
                                   size_t aDataSize, int aFaceIndex);
  static void ReleaseFTFace(FT_Face aFace);
  static FT_Error LoadFTGlyph(FT_Face aFace, uint32_t aGlyphIndex,
                              int32_t aFlags);

 private:
  static FT_Library mFTLibrary;
  static StaticMutex mFTLock;

 public:
#endif

#ifdef WIN32
  static already_AddRefed<DrawTarget> CreateDrawTargetForD3D11Texture(
      ID3D11Texture2D *aTexture, SurfaceFormat aFormat);

  /*
   * Attempts to create and install a D2D1 device from the supplied Direct3D11
   * device. Returns true on success, or false on failure and leaves the
   * D2D1/Direct3D11 devices unset.
   */
  static bool SetDirect3D11Device(ID3D11Device *aDevice);
  static RefPtr<ID3D11Device> GetDirect3D11Device();
  static RefPtr<ID2D1Device> GetD2D1Device(uint32_t *aOutSeqNo = nullptr);
  static bool HasD2D1Device();
  static RefPtr<IDWriteFactory> GetDWriteFactory();
  static RefPtr<IDWriteFactory> EnsureDWriteFactory();
  static bool SupportsD2D1();
  static RefPtr<IDWriteFontCollection> GetDWriteSystemFonts(
      bool aUpdate = false);
  static RefPtr<ID2D1DeviceContext> GetD2DDeviceContext();

  static uint64_t GetD2DVRAMUsageDrawTarget();
  static uint64_t GetD2DVRAMUsageSourceSurface();
  static void D2DCleanup();

  static already_AddRefed<ScaledFont> CreateScaledFontForDWriteFont(
      IDWriteFontFace *aFontFace, const gfxFontStyle *aStyle,
      const RefPtr<UnscaledFont> &aUnscaledFont, Float aSize,
      bool aUseEmbeddedBitmap, bool aForceGDIMode,
      IDWriteRenderingParams *aParams, Float aGamma, Float aContrast);

  static void SetSystemTextQuality(uint8_t aQuality);

 private:
  static StaticRefPtr<ID2D1Device> mD2D1Device;
  static StaticRefPtr<ID3D11Device> mD3D11Device;
  static StaticRefPtr<IDWriteFactory> mDWriteFactory;
  static bool mDWriteFactoryInitialized;
  static StaticRefPtr<IDWriteFontCollection> mDWriteSystemFonts;
  static StaticRefPtr<ID2D1DeviceContext> mMTDC;
  static StaticRefPtr<ID2D1DeviceContext> mOffMTDC;

 protected:
  // This guards access to the singleton devices above, as well as the
  // singleton devices in DrawTargetD2D1.
  static StaticMutex mDeviceLock;
  // This synchronizes access between different D2D drawtargets and their
  // implied dependency graph.
  static StaticMutex mDTDependencyLock;

  friend class DrawTargetD2D1;
#endif

 private:
  static DrawEventRecorder *mRecorder;
};

}  // namespace gfx
}  // namespace mozilla

#endif  // _MOZILLA_GFX_2D_H