1 files changed, 811 insertions, 0 deletions
diff --git a/gfx/thebes/gfxContext.h b/gfx/thebes/gfxContext.h
new file mode 100644
index 0000000000..a6ebe76e7b
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+++ b/gfx/thebes/gfxContext.h
@@ -0,0 +1,811 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_CONTEXT_H
+#define GFX_CONTEXT_H
+
+#include "gfx2DGlue.h"
+#include "gfxPattern.h"
+#include "gfxUtils.h"
+#include "nsTArray.h"
+
+#include "mozilla/EnumSet.h"
+#include "mozilla/gfx/2D.h"
+
+typedef struct _cairo cairo_t;
+class GlyphBufferAzure;
+
+namespace mozilla {
+namespace gfx {
+struct RectCornerRadii;
+}  // namespace gfx
+namespace layout {
+class TextDrawTarget;
+}  // namespace layout
+}  // namespace mozilla
+
+class ClipExporter;
+
+/* This class lives on the stack and allows gfxContext users to easily, and
+ * performantly get a gfx::Pattern to use for drawing in their current context.
+ */
+class PatternFromState {
+ public:
+  explicit PatternFromState(const gfxContext* aContext)
+      : mContext(aContext), mPattern(nullptr) {}
+  ~PatternFromState() {
+    if (mPattern) {
+      mPattern->~Pattern();
+    }
+  }
+
+  operator mozilla::gfx::Pattern&();
+
+ private:
+  mozilla::AlignedStorage2<mozilla::gfx::ColorPattern> mColorPattern;
+
+  const gfxContext* mContext;
+  mozilla::gfx::Pattern* mPattern;
+};
+
+/**
+ * This is the main class for doing actual drawing. It is initialized using
+ * a surface and can be drawn on. It manages various state information like
+ * a current transformation matrix (CTM), a current path, current color,
+ * etc.
+ *
+ * All drawing happens by creating a path and then stroking or filling it.
+ * The functions like Rectangle and Arc do not do any drawing themselves.
+ * When a path is drawn (stroked or filled), it is filled/stroked with a
+ * pattern set by SetPattern or SetColor.
+ *
+ * Note that the gfxContext takes coordinates in device pixels,
+ * as opposed to app units.
+ */
+class gfxContext final {
+#ifdef DEBUG
+#  define CURRENTSTATE_CHANGED() mAzureState.mContentChanged = true;
+#else
+#  define CURRENTSTATE_CHANGED()
+#endif
+
+  typedef mozilla::gfx::BackendType BackendType;
+  typedef mozilla::gfx::CapStyle CapStyle;
+  typedef mozilla::gfx::CompositionOp CompositionOp;
+  typedef mozilla::gfx::DeviceColor DeviceColor;
+  typedef mozilla::gfx::DrawOptions DrawOptions;
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+  typedef mozilla::gfx::JoinStyle JoinStyle;
+  typedef mozilla::gfx::FillRule FillRule;
+  typedef mozilla::gfx::Float Float;
+  typedef mozilla::gfx::Matrix Matrix;
+  typedef mozilla::gfx::Path Path;
+  typedef mozilla::gfx::Pattern Pattern;
+  typedef mozilla::gfx::Point Point;
+  typedef mozilla::gfx::Rect Rect;
+  typedef mozilla::gfx::RectCornerRadii RectCornerRadii;
+  typedef mozilla::gfx::Size Size;
+
+ public:
+  /**
+   * Initialize this context from a DrawTarget, which must be non-null.
+   * Strips any transform from aTarget, unless aPreserveTransform is true.
+   * aTarget will be flushed in the gfxContext's destructor.
+   */
+  MOZ_NONNULL(2)
+  explicit gfxContext(DrawTarget* aTarget, const Point& aDeviceOffset = Point())
+      : mDT(aTarget) {
+    mAzureState.deviceOffset = aDeviceOffset;
+    mDT->SetTransform(GetDTTransform());
+  }
+
+  MOZ_NONNULL(2)
+  gfxContext(DrawTarget* aTarget, bool aPreserveTransform) : mDT(aTarget) {
+    if (aPreserveTransform) {
+      SetMatrix(aTarget->GetTransform());
+    } else {
+      mDT->SetTransform(GetDTTransform());
+    }
+  }
+
+  ~gfxContext();
+
+  /**
+   * Initialize this context from a DrawTarget.
+   * Strips any transform from aTarget.
+   * aTarget will be flushed in the gfxContext's destructor.
+   * If aTarget is null or invalid, nullptr is returned.  The caller
+   * is responsible for handling this scenario as appropriate.
+   */
+  static mozilla::UniquePtr<gfxContext> CreateOrNull(
+      DrawTarget* aTarget, const Point& aDeviceOffset = Point());
+
+  DrawTarget* GetDrawTarget() const { return mDT; }
+
+  /**
+   * Returns the DrawTarget if it's actually a TextDrawTarget.
+   */
+  mozilla::layout::TextDrawTarget* GetTextDrawer() const;
+
+  /**
+   ** State
+   **/
+  // XXX document exactly what bits are saved
+  void Save();
+  void Restore();
+
+  /**
+   ** Paths & Drawing
+   **/
+
+  /**
+   * Fill the current path according to the current settings.
+   *
+   * Does not consume the current path.
+   */
+  void Fill() { Fill(PatternFromState(this)); }
+  void Fill(const Pattern& aPattern);
+
+  /**
+   * Forgets the current path.
+   */
+  void NewPath() {
+    mPath = nullptr;
+    mPathBuilder = nullptr;
+    mPathIsRect = false;
+    mTransformChanged = false;
+  }
+
+  /**
+   * Returns the current path.
+   */
+  already_AddRefed<Path> GetPath() {
+    EnsurePath();
+    RefPtr<Path> path(mPath);
+    return path.forget();
+  }
+
+  /**
+   * Sets the given path as the current path.
+   */
+  void SetPath(Path* path) {
+    MOZ_ASSERT(path->GetBackendType() == mDT->GetBackendType() ||
+               path->GetBackendType() == BackendType::RECORDING ||
+               (mDT->GetBackendType() == BackendType::DIRECT2D1_1 &&
+                path->GetBackendType() == BackendType::DIRECT2D));
+    mPath = path;
+    mPathBuilder = nullptr;
+    mPathIsRect = false;
+    mTransformChanged = false;
+  }
+
+  /**
+   * Draws the rectangle given by rect.
+   */
+  void Rectangle(const gfxRect& rect) { return Rectangle(rect, false); }
+  void SnappedRectangle(const gfxRect& rect) { return Rectangle(rect, true); }
+
+ private:
+  void Rectangle(const gfxRect& rect, bool snapToPixels);
+
+ public:
+  /**
+   ** Transformation Matrix manipulation
+   **/
+
+  /**
+   * Post-multiplies 'other' onto the current CTM, i.e. this
+   * matrix's transformation will take place before the previously set
+   * transformations.
+   */
+  void Multiply(const gfxMatrix& aMatrix) { Multiply(ToMatrix(aMatrix)); }
+  void Multiply(const Matrix& aOther) {
+    CURRENTSTATE_CHANGED()
+    ChangeTransform(aOther * mAzureState.transform);
+  }
+
+  /**
+   * Replaces the current transformation matrix with matrix.
+   */
+  void SetMatrix(const Matrix& aMatrix) {
+    CURRENTSTATE_CHANGED()
+    ChangeTransform(aMatrix);
+  }
+  void SetMatrixDouble(const gfxMatrix& aMatrix) {
+    SetMatrix(ToMatrix(aMatrix));
+  }
+
+  void SetCrossProcessPaintScale(float aScale) {
+    MOZ_ASSERT(mCrossProcessPaintScale == 1.0f,
+               "Should only be initialized once");
+    mCrossProcessPaintScale = aScale;
+  }
+
+  float GetCrossProcessPaintScale() const { return mCrossProcessPaintScale; }
+
+  /**
+   * Returns the current transformation matrix.
+   */
+  Matrix CurrentMatrix() const { return mAzureState.transform; }
+  gfxMatrix CurrentMatrixDouble() const {
+    return ThebesMatrix(CurrentMatrix());
+  }
+
+  /**
+   * Converts a point from device to user coordinates using the inverse
+   * transformation matrix.
+   */
+  gfxPoint DeviceToUser(const gfxPoint& aPoint) const {
+    return ThebesPoint(
+        mAzureState.transform.Inverse().TransformPoint(ToPoint(aPoint)));
+  }
+
+  /**
+   * Converts a size from device to user coordinates. This does not apply
+   * translation components of the matrix.
+   */
+  Size DeviceToUser(const Size& aSize) const {
+    return mAzureState.transform.Inverse().TransformSize(aSize);
+  }
+
+  /**
+   * Converts a rectangle from device to user coordinates; this has the
+   * same effect as using DeviceToUser on both the rectangle's point and
+   * size.
+   */
+  gfxRect DeviceToUser(const gfxRect& aRect) const {
+    return ThebesRect(
+        mAzureState.transform.Inverse().TransformBounds(ToRect(aRect)));
+  }
+
+  /**
+   * Converts a point from user to device coordinates using the transformation
+   * matrix.
+   */
+  gfxPoint UserToDevice(const gfxPoint& aPoint) const {
+    return ThebesPoint(mAzureState.transform.TransformPoint(ToPoint(aPoint)));
+  }
+
+  /**
+   * Converts a size from user to device coordinates. This does not apply
+   * translation components of the matrix.
+   */
+  Size UserToDevice(const Size& aSize) const {
+    const auto& mtx = mAzureState.transform;
+    return Size(aSize.width * mtx._11 + aSize.height * mtx._12,
+                aSize.width * mtx._21 + aSize.height * mtx._22);
+  }
+
+  /**
+   * Converts a rectangle from user to device coordinates.  The
+   * resulting rectangle is the minimum device-space rectangle that
+   * encloses the user-space rectangle given.
+   */
+  gfxRect UserToDevice(const gfxRect& rect) const {
+    return ThebesRect(mAzureState.transform.TransformBounds(ToRect(rect)));
+  }
+
+  /**
+   * Takes the given rect and tries to align it to device pixels.  If
+   * this succeeds, the method will return true, and the rect will
+   * be in device coordinates (already transformed by the CTM).  If it
+   * fails, the method will return false, and the rect will not be
+   * changed.
+   *
+   * aOptions parameter:
+   *   If IgnoreScale is set, then snapping will take place even if the CTM
+   *   has a scale applied. Snapping never takes place if there is a rotation
+   *   in the CTM.
+   *
+   *   If PrioritizeSize is set, the rect's dimensions will first be snapped
+   *   and then its position aligned to device pixels, rather than snapping
+   *   the position of each edge independently.
+   */
+  enum class SnapOption : uint8_t {
+    IgnoreScale = 1,
+    PrioritizeSize = 2,
+  };
+  using SnapOptions = mozilla::EnumSet<SnapOption>;
+  bool UserToDevicePixelSnapped(gfxRect& rect, SnapOptions aOptions = {}) const;
+
+  /**
+   * Takes the given point and tries to align it to device pixels.  If
+   * this succeeds, the method will return true, and the point will
+   * be in device coordinates (already transformed by the CTM).  If it
+   * fails, the method will return false, and the point will not be
+   * changed.
+   *
+   * If ignoreScale is true, then snapping will take place even if
+   * the CTM has a scale applied.  Snapping never takes place if
+   * there is a rotation in the CTM.
+   */
+  bool UserToDevicePixelSnapped(gfxPoint& pt, bool ignoreScale = false) const;
+
+  /**
+   ** Painting sources
+   **/
+
+  /**
+   * Set a solid color to use for drawing.  This color is in the device color
+   * space and is not transformed.
+   */
+  void SetDeviceColor(const DeviceColor& aColor) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.pattern = nullptr;
+    mAzureState.color = aColor;
+  }
+
+  /**
+   * Gets the current color.  It's returned in the device color space.
+   * returns false if there is something other than a color
+   *         set as the current source (pattern, surface, etc)
+   */
+  bool GetDeviceColor(DeviceColor& aColorOut) const;
+
+  /**
+   * Returns true if color is neither opaque nor transparent (i.e. alpha is not
+   * 0 or 1), and false otherwise. If true, aColorOut is set on output.
+   */
+  bool HasNonOpaqueNonTransparentColor(DeviceColor& aColorOut) const {
+    return GetDeviceColor(aColorOut) && 0.f < aColorOut.a && aColorOut.a < 1.f;
+  }
+
+  /**
+   * Set a solid color in the sRGB color space to use for drawing.
+   * If CMS is not enabled, the color is treated as a device-space color
+   * and this call is identical to SetDeviceColor().
+   */
+  void SetColor(const mozilla::gfx::sRGBColor& aColor) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.pattern = nullptr;
+    mAzureState.color = ToDeviceColor(aColor);
+  }
+
+  /**
+   * Uses a pattern for drawing.
+   */
+  void SetPattern(gfxPattern* pattern) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.patternTransformChanged = false;
+    mAzureState.pattern = pattern;
+  }
+
+  /**
+   * Get the source pattern (solid color, normal pattern, surface, etc)
+   */
+  already_AddRefed<gfxPattern> GetPattern() const;
+
+  /**
+   ** Painting
+   **/
+  /**
+   * Paints the current source surface/pattern everywhere in the current
+   * clip region.
+   */
+  void Paint(Float alpha = 1.0) const;
+
+  /**
+   ** Line Properties
+   **/
+
+  // Set the dash pattern, applying devPxScale to convert passed-in lengths
+  // to device pixels (used by the SVGUtils::SetupStrokeGeometry caller,
+  // which has the desired dash pattern in CSS px).
+  void SetDash(const Float* dashes, int ndash, Float offset, Float devPxScale);
+
+  // Return true if dashing is set, false if it's not enabled or the
+  // context is in an error state.  |offset| can be nullptr to mean
+  // "don't care".
+  bool CurrentDash(FallibleTArray<Float>& dashes, Float* offset) const;
+
+  /**
+   * Sets the line width that's used for line drawing.
+   */
+  void SetLineWidth(Float width) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.strokeOptions.mLineWidth = width;
+  }
+
+  /**
+   * Returns the currently set line width.
+   *
+   * @see SetLineWidth
+   */
+  Float CurrentLineWidth() const {
+    return mAzureState.strokeOptions.mLineWidth;
+  }
+
+  /**
+   * Sets the line caps, i.e. how line endings are drawn.
+   */
+  void SetLineCap(CapStyle cap) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.strokeOptions.mLineCap = cap;
+  }
+  CapStyle CurrentLineCap() const { return mAzureState.strokeOptions.mLineCap; }
+
+  /**
+   * Sets the line join, i.e. how the connection between two lines is
+   * drawn.
+   */
+  void SetLineJoin(JoinStyle join) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.strokeOptions.mLineJoin = join;
+  }
+  JoinStyle CurrentLineJoin() const {
+    return mAzureState.strokeOptions.mLineJoin;
+  }
+
+  void SetMiterLimit(Float limit) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.strokeOptions.mMiterLimit = limit;
+  }
+  Float CurrentMiterLimit() const {
+    return mAzureState.strokeOptions.mMiterLimit;
+  }
+
+  /**
+   * Sets the operator used for all further drawing. The operator affects
+   * how drawing something will modify the destination. For example, the
+   * OVER operator will do alpha blending of source and destination, while
+   * SOURCE will replace the destination with the source.
+   */
+  void SetOp(CompositionOp aOp) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.op = aOp;
+  }
+  CompositionOp CurrentOp() const { return mAzureState.op; }
+
+  void SetAntialiasMode(mozilla::gfx::AntialiasMode aMode) {
+    CURRENTSTATE_CHANGED()
+    mAzureState.aaMode = aMode;
+  }
+  mozilla::gfx::AntialiasMode CurrentAntialiasMode() const {
+    return mAzureState.aaMode;
+  }
+
+  /**
+   ** Clipping
+   **/
+
+  /**
+   * Clips all further drawing to the current path.
+   * This does not consume the current path.
+   */
+  void Clip();
+
+  /**
+   * Helper functions that will create a rect path and call Clip().
+   * Any current path will be destroyed by these functions!
+   */
+  void Clip(const gfxRect& aRect) { Clip(ToRect(aRect)); }
+  void Clip(const Rect& rect);            // will clip to a rect
+  void SnappedClip(const gfxRect& rect);  // snap rect and clip to the result
+  void Clip(Path* aPath);
+
+  void PopClip() {
+    MOZ_ASSERT(!mAzureState.pushedClips.IsEmpty());
+    mAzureState.pushedClips.RemoveLastElement();
+    mDT->PopClip();
+  }
+
+  enum ClipExtentsSpace {
+    eUserSpace = 0,
+    eDeviceSpace = 1,
+  };
+
+  /**
+   * According to aSpace, this function will return the current bounds of
+   * the clip region in user space or device space.
+   */
+  gfxRect GetClipExtents(ClipExtentsSpace aSpace = eUserSpace) const;
+
+  /**
+   * Exports the current clip using the provided exporter.
+   */
+  bool ExportClip(ClipExporter& aExporter) const;
+
+  /**
+   * Groups
+   */
+  void PushGroupForBlendBack(gfxContentType content, Float aOpacity = 1.0f,
+                             mozilla::gfx::SourceSurface* aMask = nullptr,
+                             const Matrix& aMaskTransform = Matrix()) const {
+    mDT->PushLayer(content == gfxContentType::COLOR, aOpacity, aMask,
+                   aMaskTransform);
+  }
+
+  void PopGroupAndBlend() const { mDT->PopLayer(); }
+
+  Point GetDeviceOffset() const { return mAzureState.deviceOffset; }
+  void SetDeviceOffset(const Point& aOffset) {
+    mAzureState.deviceOffset = aOffset;
+  }
+
+#ifdef MOZ_DUMP_PAINTING
+  /**
+   * Debug functions to encode the current surface as a PNG and export it.
+   */
+
+  /**
+   * Writes a binary PNG file.
+   */
+  void WriteAsPNG(const char* aFile);
+
+  /**
+   * Write as a PNG encoded Data URL to stdout.
+   */
+  void DumpAsDataURI();
+
+  /**
+   * Copy a PNG encoded Data URL to the clipboard.
+   */
+  void CopyAsDataURI();
+#endif
+
+ private:
+  friend class PatternFromState;
+  friend class GlyphBufferAzure;
+
+  typedef mozilla::gfx::sRGBColor sRGBColor;
+  typedef mozilla::gfx::StrokeOptions StrokeOptions;
+  typedef mozilla::gfx::PathBuilder PathBuilder;
+  typedef mozilla::gfx::SourceSurface SourceSurface;
+
+  struct AzureState {
+    AzureState()
+        : op(CompositionOp::OP_OVER),
+          color(0, 0, 0, 1.0f),
+          aaMode(mozilla::gfx::AntialiasMode::SUBPIXEL),
+          patternTransformChanged(false)
+#ifdef DEBUG
+          ,
+          mContentChanged(false)
+#endif
+    {
+    }
+
+    CompositionOp op;
+    DeviceColor color;
+    RefPtr<gfxPattern> pattern;
+    Matrix transform;
+    struct PushedClip {
+      RefPtr<Path> path;
+      Rect rect;
+      Matrix transform;
+    };
+    CopyableTArray<PushedClip> pushedClips;
+    CopyableTArray<Float> dashPattern;
+    StrokeOptions strokeOptions;
+    mozilla::gfx::AntialiasMode aaMode;
+    bool patternTransformChanged;
+    Matrix patternTransform;
+    DeviceColor fontSmoothingBackgroundColor;
+    // This is used solely for using minimal intermediate surface size.
+    Point deviceOffset;
+#ifdef DEBUG
+    // Whether the content of this AzureState changed after construction.
+    bool mContentChanged;
+#endif
+  };
+
+  // This ensures mPath contains a valid path (in user space!)
+  void EnsurePath();
+  // This ensures mPathBuilder contains a valid PathBuilder (in user space!)
+  void EnsurePathBuilder();
+  CompositionOp GetOp() const;
+  void ChangeTransform(const Matrix& aNewMatrix,
+                       bool aUpdatePatternTransform = true);
+  Rect GetAzureDeviceSpaceClipBounds() const;
+  Matrix GetDTTransform() const {
+    Matrix mat = mAzureState.transform;
+    mat.PostTranslate(-mAzureState.deviceOffset);
+    return mat;
+  }
+
+  bool mPathIsRect = false;
+  bool mTransformChanged = false;
+  Matrix mPathTransform;
+  Rect mRect;
+  RefPtr<PathBuilder> mPathBuilder;
+  RefPtr<Path> mPath;
+  AzureState mAzureState;
+  nsTArray<AzureState> mSavedStates;
+
+  // Iterate over all clips in the saved and current states, calling aLambda
+  // with each of them.
+  template <typename F>
+  void ForAllClips(F&& aLambda) const;
+
+  const AzureState& CurrentState() const { return mAzureState; }
+
+  RefPtr<DrawTarget> const mDT;
+  float mCrossProcessPaintScale = 1.0f;
+
+#ifdef DEBUG
+#  undef CURRENTSTATE_CHANGED
+#endif
+};
+
+/**
+ * Sentry helper class for functions with multiple return points that need to
+ * call Save() on a gfxContext and have Restore() called automatically on the
+ * gfxContext before they return.
+ */
+class MOZ_STACK_CLASS gfxContextAutoSaveRestore final {
+ public:
+  gfxContextAutoSaveRestore() : mContext(nullptr) {}
+
+  explicit gfxContextAutoSaveRestore(gfxContext* aContext)
+      : mContext(aContext) {
+    mContext->Save();
+  }
+
+  ~gfxContextAutoSaveRestore() { Restore(); }
+
+  void SetContext(gfxContext* aContext) {
+    MOZ_ASSERT(!mContext, "no context?");
+    mContext = aContext;
+    mContext->Save();
+  }
+
+  void EnsureSaved(gfxContext* aContext) {
+    MOZ_ASSERT(!mContext || mContext == aContext, "wrong context");
+    if (!mContext) {
+      mContext = aContext;
+      mContext->Save();
+    }
+  }
+
+  void Restore() {
+    if (mContext) {
+      mContext->Restore();
+      mContext = nullptr;
+    }
+  }
+
+ private:
+  gfxContext* mContext;
+};
+
+/**
+ * Sentry helper class for functions with multiple return points that need to
+ * back up the current matrix of a context and have it automatically restored
+ * before they return.
+ */
+class MOZ_STACK_CLASS gfxContextMatrixAutoSaveRestore final {
+ public:
+  gfxContextMatrixAutoSaveRestore() : mContext(nullptr) {}
+
+  explicit gfxContextMatrixAutoSaveRestore(gfxContext* aContext)
+      : mContext(aContext), mMatrix(aContext->CurrentMatrix()) {}
+
+  ~gfxContextMatrixAutoSaveRestore() {
+    if (mContext) {
+      mContext->SetMatrix(mMatrix);
+    }
+  }
+
+  void SetContext(gfxContext* aContext) {
+    NS_ASSERTION(!mContext, "Not going to restore the matrix on some context!");
+    mContext = aContext;
+    mMatrix = aContext->CurrentMatrix();
+  }
+
+  void Restore() {
+    if (mContext) {
+      mContext->SetMatrix(mMatrix);
+      mContext = nullptr;
+    }
+  }
+
+  const mozilla::gfx::Matrix& Matrix() {
+    MOZ_ASSERT(mContext, "mMatrix doesn't contain a useful matrix");
+    return mMatrix;
+  }
+
+  bool HasMatrix() const { return !!mContext; }
+
+ private:
+  gfxContext* mContext;
+  mozilla::gfx::Matrix mMatrix;
+};
+
+class MOZ_STACK_CLASS gfxGroupForBlendAutoSaveRestore final {
+ public:
+  using Float = mozilla::gfx::Float;
+  using Matrix = mozilla::gfx::Matrix;
+
+  explicit gfxGroupForBlendAutoSaveRestore(gfxContext* aContext)
+      : mContext(aContext) {}
+
+  ~gfxGroupForBlendAutoSaveRestore() {
+    if (mPushedGroup) {
+      mContext->PopGroupAndBlend();
+    }
+  }
+
+  void PushGroupForBlendBack(gfxContentType aContent, Float aOpacity = 1.0f,
+                             mozilla::gfx::SourceSurface* aMask = nullptr,
+                             const Matrix& aMaskTransform = Matrix()) {
+    MOZ_ASSERT(!mPushedGroup, "Already called PushGroupForBlendBack once");
+    mContext->PushGroupForBlendBack(aContent, aOpacity, aMask, aMaskTransform);
+    mPushedGroup = true;
+  }
+
+ private:
+  gfxContext* mContext;
+  bool mPushedGroup = false;
+};
+
+class MOZ_STACK_CLASS gfxClipAutoSaveRestore final {
+ public:
+  using Rect = mozilla::gfx::Rect;
+
+  explicit gfxClipAutoSaveRestore(gfxContext* aContext) : mContext(aContext) {}
+
+  void Clip(const gfxRect& aRect) { Clip(ToRect(aRect)); }
+
+  void Clip(const Rect& aRect) {
+    MOZ_ASSERT(!mClipped, "Already called Clip once");
+    mContext->Clip(aRect);
+    mClipped = true;
+  }
+
+  void TransformedClip(const gfxMatrix& aTransform, const gfxRect& aRect) {
+    MOZ_ASSERT(!mClipped, "Already called Clip once");
+    if (aTransform.IsSingular()) {
+      return;
+    }
+    gfxContextMatrixAutoSaveRestore matrixAutoSaveRestore(mContext);
+    mContext->Multiply(aTransform);
+    mContext->Clip(aRect);
+    mClipped = true;
+  }
+
+  ~gfxClipAutoSaveRestore() {
+    if (mClipped) {
+      mContext->PopClip();
+    }
+  }
+
+ private:
+  gfxContext* mContext;
+  bool mClipped = false;
+};
+
+class MOZ_STACK_CLASS DrawTargetAutoDisableSubpixelAntialiasing final {
+ public:
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+
+  DrawTargetAutoDisableSubpixelAntialiasing(DrawTarget* aDT, bool aDisable)
+      : mSubpixelAntialiasingEnabled(false) {
+    if (aDisable) {
+      mDT = aDT;
+      mSubpixelAntialiasingEnabled = mDT->GetPermitSubpixelAA();
+      mDT->SetPermitSubpixelAA(false);
+    }
+  }
+  ~DrawTargetAutoDisableSubpixelAntialiasing() {
+    if (mDT) {
+      mDT->SetPermitSubpixelAA(mSubpixelAntialiasingEnabled);
+    }
+  }
+
+ private:
+  RefPtr<DrawTarget> mDT;
+  bool mSubpixelAntialiasingEnabled;
+};
+
+/* This interface should be implemented to handle exporting the clip from a
+ * context.
+ */
+class ClipExporter : public mozilla::gfx::PathSink {
+ public:
+  virtual void BeginClip(const mozilla::gfx::Matrix& aMatrix) = 0;
+  virtual void EndClip() = 0;
+};
+
+#endif /* GFX_CONTEXT_H */