diff -r 000000000000 -r 6474c204b198 gfx/thebes/gfxContext.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/thebes/gfxContext.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,2373 @@
+/* -*- 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/. */
+
+#ifdef _MSC_VER
+#define _USE_MATH_DEFINES
+#endif
+#include <math.h>
+
+#include "mozilla/Alignment.h"
+
+#include "cairo.h"
+
+#include "gfxContext.h"
+
+#include "gfxColor.h"
+#include "gfxMatrix.h"
+#include "gfxASurface.h"
+#include "gfxPattern.h"
+#include "gfxPlatform.h"
+#include "gfxTeeSurface.h"
+#include "GeckoProfiler.h"
+#include "gfx2DGlue.h"
+#include "mozilla/gfx/PathHelpers.h"
+#include <algorithm>
+
+#if CAIRO_HAS_DWRITE_FONT
+#include "gfxWindowsPlatform.h"
+#endif
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+UserDataKey gfxContext::sDontUseAsSourceKey;
+
+/* 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 GeneralPattern
+{
+public:    
+  GeneralPattern(gfxContext *aContext) : mContext(aContext), mPattern(nullptr) {}
+  ~GeneralPattern() { if (mPattern) { mPattern->~Pattern(); } }
+
+  operator mozilla::gfx::Pattern&()
+  {
+    gfxContext::AzureState &state = mContext->CurrentState();
+
+    if (state.pattern) {
+      return *state.pattern->GetPattern(mContext->mDT, state.patternTransformChanged ? &state.patternTransform : nullptr);
+    } else if (state.sourceSurface) {
+      Matrix transform = state.surfTransform;
+
+      if (state.patternTransformChanged) {
+        Matrix mat = mContext->GetDTTransform();
+        mat.Invert();
+
+        transform = transform * state.patternTransform * mat;
+      }
+
+      mPattern = new (mSurfacePattern.addr())
+        SurfacePattern(state.sourceSurface, ExtendMode::CLAMP, transform);
+      return *mPattern;
+    } else {
+      mPattern = new (mColorPattern.addr())
+        ColorPattern(state.color);
+      return *mPattern;
+    }
+  }
+
+private:
+  union {
+    mozilla::AlignedStorage2<mozilla::gfx::ColorPattern> mColorPattern;
+    mozilla::AlignedStorage2<mozilla::gfx::SurfacePattern> mSurfacePattern;
+  };
+
+  gfxContext *mContext;
+  Pattern *mPattern;
+};
+
+gfxContext::gfxContext(gfxASurface *surface)
+  : mRefCairo(nullptr)
+  , mSurface(surface)
+{
+  MOZ_COUNT_CTOR(gfxContext);
+
+  mCairo = cairo_create(surface->CairoSurface());
+  mFlags = surface->GetDefaultContextFlags();
+  if (mSurface->GetRotateForLandscape()) {
+    // Rotate page 90 degrees to draw landscape page on portrait paper
+    gfxIntSize size = mSurface->GetSize();
+    Translate(gfxPoint(0, size.width));
+    gfxMatrix matrix(0, -1,
+                      1,  0,
+                      0,  0);
+    Multiply(matrix);
+  }
+}
+
+gfxContext::gfxContext(DrawTarget *aTarget, const Point& aDeviceOffset)
+  : mPathIsRect(false)
+  , mTransformChanged(false)
+  , mCairo(nullptr)
+  , mRefCairo(nullptr)
+  , mSurface(nullptr)
+  , mFlags(0)
+  , mDT(aTarget)
+  , mOriginalDT(aTarget)
+{
+  MOZ_COUNT_CTOR(gfxContext);
+
+  mStateStack.SetLength(1);
+  CurrentState().drawTarget = mDT;
+  CurrentState().deviceOffset = aDeviceOffset;
+  mDT->SetTransform(Matrix());
+}
+
+/* static */ already_AddRefed<gfxContext>
+gfxContext::ContextForDrawTarget(DrawTarget* aTarget)
+{
+  Matrix transform = aTarget->GetTransform();
+  nsRefPtr<gfxContext> result = new gfxContext(aTarget);
+  result->SetMatrix(ThebesMatrix(transform));
+  return result.forget();
+}
+
+gfxContext::~gfxContext()
+{
+  if (mCairo) {
+    cairo_destroy(mCairo);
+  }
+  if (mRefCairo) {
+    cairo_destroy(mRefCairo);
+  }
+  if (mDT) {
+    for (int i = mStateStack.Length() - 1; i >= 0; i--) {
+      for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
+        mDT->PopClip();
+      }
+
+      if (mStateStack[i].clipWasReset) {
+        break;
+      }
+    }
+    mDT->Flush();
+  }
+  MOZ_COUNT_DTOR(gfxContext);
+}
+
+gfxASurface *
+gfxContext::OriginalSurface()
+{
+    if (mCairo || mSurface) {
+        return mSurface;
+    }
+
+    if (mOriginalDT && mOriginalDT->GetType() == BackendType::CAIRO) {
+        cairo_surface_t *s =
+            (cairo_surface_t*)mOriginalDT->GetNativeSurface(NativeSurfaceType::CAIRO_SURFACE);
+        if (s) {
+            mSurface = gfxASurface::Wrap(s);
+            return mSurface;
+        }
+    }
+    return nullptr;
+}
+
+already_AddRefed<gfxASurface>
+gfxContext::CurrentSurface(gfxFloat *dx, gfxFloat *dy)
+{
+  if (mCairo) {
+    cairo_surface_t *s = cairo_get_group_target(mCairo);
+    if (s == mSurface->CairoSurface()) {
+        if (dx && dy)
+            cairo_surface_get_device_offset(s, dx, dy);
+        nsRefPtr<gfxASurface> ret = mSurface;
+        return ret.forget();
+    }
+
+    if (dx && dy)
+        cairo_surface_get_device_offset(s, dx, dy);
+    return gfxASurface::Wrap(s);
+  } else {
+    if (mDT->GetType() == BackendType::CAIRO) {
+        cairo_surface_t *s =
+            (cairo_surface_t*)mDT->GetNativeSurface(NativeSurfaceType::CAIRO_SURFACE);
+        if (s) {
+            if (dx && dy) {
+                *dx = -CurrentState().deviceOffset.x;
+                *dy = -CurrentState().deviceOffset.y;
+            }
+            return gfxASurface::Wrap(s);
+        }
+    }
+
+    if (dx && dy) {
+      *dx = *dy = 0;
+    }
+    // An Azure context doesn't have a surface backing it.
+    return nullptr;
+  }
+}
+
+cairo_t *
+gfxContext::GetCairo()
+{
+  if (mCairo) {
+    return mCairo;
+  }
+
+  if (mDT->GetType() == BackendType::CAIRO) {
+    cairo_t *ctx =
+      (cairo_t*)mDT->GetNativeSurface(NativeSurfaceType::CAIRO_CONTEXT);
+    if (ctx) {
+      return ctx;
+    }
+  }
+
+  if (mRefCairo) {
+    // Set transform!
+    return mRefCairo;
+  }
+
+  mRefCairo = cairo_create(gfxPlatform::GetPlatform()->ScreenReferenceSurface()->CairoSurface()); 
+
+  return mRefCairo;
+}
+
+void
+gfxContext::Save()
+{
+  if (mCairo) {
+    cairo_save(mCairo);
+  } else {
+    CurrentState().transform = mTransform;
+    mStateStack.AppendElement(AzureState(CurrentState()));
+    CurrentState().clipWasReset = false;
+    CurrentState().pushedClips.Clear();
+  }
+}
+
+void
+gfxContext::Restore()
+{
+  if (mCairo) {
+    cairo_restore(mCairo);
+  } else {
+    for (unsigned int c = 0; c < CurrentState().pushedClips.Length(); c++) {
+      mDT->PopClip();
+    }
+
+    if (CurrentState().clipWasReset &&
+        CurrentState().drawTarget == mStateStack[mStateStack.Length() - 2].drawTarget) {
+      PushClipsToDT(mDT);
+    }
+
+    mStateStack.RemoveElementAt(mStateStack.Length() - 1);
+
+    mDT = CurrentState().drawTarget;
+
+    ChangeTransform(CurrentState().transform, false);
+  }
+}
+
+// drawing
+void
+gfxContext::NewPath()
+{
+  if (mCairo) {
+    cairo_new_path(mCairo);
+  } else {
+    mPath = nullptr;
+    mPathBuilder = nullptr;
+    mPathIsRect = false;
+    mTransformChanged = false;
+  }
+}
+
+void
+gfxContext::ClosePath()
+{
+  if (mCairo) {
+    cairo_close_path(mCairo);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->Close();
+  }
+}
+
+already_AddRefed<gfxPath> gfxContext::CopyPath()
+{
+  nsRefPtr<gfxPath> path;
+  if (mCairo) {
+    path = new gfxPath(cairo_copy_path(mCairo));
+  } else {
+    EnsurePath();
+    path = new gfxPath(mPath);
+  }
+  return path.forget();
+}
+
+void gfxContext::SetPath(gfxPath* path)
+{
+  if (mCairo) {
+    cairo_new_path(mCairo);
+    if (path->mPath->status == CAIRO_STATUS_SUCCESS && path->mPath->num_data != 0)
+        cairo_append_path(mCairo, path->mPath);
+  } else {
+    MOZ_ASSERT(path->mMoz2DPath, "Can't mix cairo and azure paths!");
+    MOZ_ASSERT(path->mMoz2DPath->GetBackendType() == mDT->GetType());
+    mPath = path->mMoz2DPath;
+    mPathBuilder = nullptr;
+    mPathIsRect = false;
+    mTransformChanged = false;
+  }
+}
+
+gfxPoint
+gfxContext::CurrentPoint()
+{
+  if (mCairo) {
+    double x, y;
+    cairo_get_current_point(mCairo, &x, &y);
+    return gfxPoint(x, y);
+  } else {
+    EnsurePathBuilder();
+    return ThebesPoint(mPathBuilder->CurrentPoint());
+  }
+}
+
+void
+gfxContext::Stroke()
+{
+  if (mCairo) {
+    cairo_stroke_preserve(mCairo);
+  } else {
+    AzureState &state = CurrentState();
+    if (mPathIsRect) {
+      MOZ_ASSERT(!mTransformChanged);
+
+      mDT->StrokeRect(mRect, GeneralPattern(this),
+                      state.strokeOptions,
+                      DrawOptions(1.0f, GetOp(), state.aaMode));
+    } else {
+      EnsurePath();
+
+      mDT->Stroke(mPath, GeneralPattern(this), state.strokeOptions,
+                  DrawOptions(1.0f, GetOp(), state.aaMode));
+    }
+  }
+}
+
+void
+gfxContext::Fill()
+{
+  PROFILER_LABEL("gfxContext", "Fill");
+  if (mCairo) {
+    cairo_fill_preserve(mCairo);
+  } else {
+    FillAzure(1.0f);
+  }
+}
+
+void
+gfxContext::FillWithOpacity(gfxFloat aOpacity)
+{
+  if (mCairo) {
+    // This method exists in the hope that one day cairo gets a direct
+    // API for this, and then we would change this method to use that
+    // API instead.
+    if (aOpacity != 1.0) {
+      gfxContextAutoSaveRestore saveRestore(this);
+      Clip();
+      Paint(aOpacity);
+    } else {
+      Fill();
+    }
+  } else {
+    FillAzure(Float(aOpacity));
+  }
+}
+
+void
+gfxContext::MoveTo(const gfxPoint& pt)
+{
+  if (mCairo) {
+    cairo_move_to(mCairo, pt.x, pt.y);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->MoveTo(ToPoint(pt));
+  }
+}
+
+void
+gfxContext::NewSubPath()
+{
+  if (mCairo) {
+    cairo_new_sub_path(mCairo);
+  } else {
+    // XXX - This has no users, we should kill it, it should be equivelant to a
+    // MoveTo to the path's current point.
+  }
+}
+
+void
+gfxContext::LineTo(const gfxPoint& pt)
+{
+  if (mCairo) {
+    cairo_line_to(mCairo, pt.x, pt.y);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->LineTo(ToPoint(pt));
+  }
+}
+
+void
+gfxContext::CurveTo(const gfxPoint& pt1, const gfxPoint& pt2, const gfxPoint& pt3)
+{
+  if (mCairo) {
+    cairo_curve_to(mCairo, pt1.x, pt1.y, pt2.x, pt2.y, pt3.x, pt3.y);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->BezierTo(ToPoint(pt1), ToPoint(pt2), ToPoint(pt3));
+  }
+}
+
+void
+gfxContext::QuadraticCurveTo(const gfxPoint& pt1, const gfxPoint& pt2)
+{
+  if (mCairo) {
+    double cx, cy;
+    cairo_get_current_point(mCairo, &cx, &cy);
+    cairo_curve_to(mCairo,
+                   (cx + pt1.x * 2.0) / 3.0,
+                   (cy + pt1.y * 2.0) / 3.0,
+                   (pt1.x * 2.0 + pt2.x) / 3.0,
+                   (pt1.y * 2.0 + pt2.y) / 3.0,
+                   pt2.x,
+                   pt2.y);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->QuadraticBezierTo(ToPoint(pt1), ToPoint(pt2));
+  }
+}
+
+void
+gfxContext::Arc(const gfxPoint& center, gfxFloat radius,
+                gfxFloat angle1, gfxFloat angle2)
+{
+  if (mCairo) {
+    cairo_arc(mCairo, center.x, center.y, radius, angle1, angle2);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->Arc(ToPoint(center), Float(radius), Float(angle1), Float(angle2));
+  }
+}
+
+void
+gfxContext::NegativeArc(const gfxPoint& center, gfxFloat radius,
+                        gfxFloat angle1, gfxFloat angle2)
+{
+  if (mCairo) {
+    cairo_arc_negative(mCairo, center.x, center.y, radius, angle1, angle2);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->Arc(ToPoint(center), Float(radius), Float(angle2), Float(angle1));
+  }
+}
+
+void
+gfxContext::Line(const gfxPoint& start, const gfxPoint& end)
+{
+  if (mCairo) {
+    MoveTo(start);
+    LineTo(end);
+  } else {
+    EnsurePathBuilder();
+    mPathBuilder->MoveTo(ToPoint(start));
+    mPathBuilder->LineTo(ToPoint(end));
+  }
+}
+
+// XXX snapToPixels is only valid when snapping for filled
+// rectangles and for even-width stroked rectangles.
+// For odd-width stroked rectangles, we need to offset x/y by
+// 0.5...
+void
+gfxContext::Rectangle(const gfxRect& rect, bool snapToPixels)
+{
+  if (mCairo) {
+    if (snapToPixels) {
+        gfxRect snappedRect(rect);
+
+        if (UserToDevicePixelSnapped(snappedRect, true))
+        {
+            cairo_matrix_t mat;
+            cairo_get_matrix(mCairo, &mat);
+            cairo_identity_matrix(mCairo);
+            Rectangle(snappedRect);
+            cairo_set_matrix(mCairo, &mat);
+
+            return;
+        }
+    }
+
+    cairo_rectangle(mCairo, rect.X(), rect.Y(), rect.Width(), rect.Height());
+  } else {
+    Rect rec = ToRect(rect);
+
+    if (snapToPixels) {
+      gfxRect newRect(rect);
+      if (UserToDevicePixelSnapped(newRect, true)) {
+        gfxMatrix mat = ThebesMatrix(mTransform);
+        mat.Invert();
+
+        // We need the user space rect.
+        rec = ToRect(mat.TransformBounds(newRect));
+      }
+    }
+
+    if (!mPathBuilder && !mPathIsRect) {
+      mPathIsRect = true;
+      mRect = rec;
+      return;
+    }
+
+    EnsurePathBuilder();
+
+    mPathBuilder->MoveTo(rec.TopLeft());
+    mPathBuilder->LineTo(rec.TopRight());
+    mPathBuilder->LineTo(rec.BottomRight());
+    mPathBuilder->LineTo(rec.BottomLeft());
+    mPathBuilder->Close();
+  }
+}
+
+void
+gfxContext::Ellipse(const gfxPoint& center, const gfxSize& dimensions)
+{
+  gfxSize halfDim = dimensions / 2.0;
+  gfxRect r(center - gfxPoint(halfDim.width, halfDim.height), dimensions);
+  gfxCornerSizes c(halfDim, halfDim, halfDim, halfDim);
+
+  RoundedRectangle (r, c);
+}
+
+void
+gfxContext::Polygon(const gfxPoint *points, uint32_t numPoints)
+{
+  if (mCairo) {
+    if (numPoints == 0)
+        return;
+
+    cairo_move_to(mCairo, points[0].x, points[0].y);
+    for (uint32_t i = 1; i < numPoints; ++i) {
+        cairo_line_to(mCairo, points[i].x, points[i].y);
+    }
+  } else {
+    if (numPoints == 0) {
+      return;
+    }
+
+    EnsurePathBuilder();
+
+    mPathBuilder->MoveTo(ToPoint(points[0]));
+    for (uint32_t i = 1; i < numPoints; i++) {
+      mPathBuilder->LineTo(ToPoint(points[i]));
+    }
+  }
+}
+
+void
+gfxContext::DrawSurface(gfxASurface *surface, const gfxSize& size)
+{
+  if (mCairo) {
+    cairo_save(mCairo);
+    cairo_set_source_surface(mCairo, surface->CairoSurface(), 0, 0);
+    cairo_new_path(mCairo);
+
+    // pixel-snap this
+    Rectangle(gfxRect(gfxPoint(0.0, 0.0), size), true);
+
+    cairo_fill(mCairo);
+    cairo_restore(mCairo);
+  } else {
+    // Lifetime needs to be limited here since we may wrap surface's data.
+    RefPtr<SourceSurface> surf =
+      gfxPlatform::GetPlatform()->GetSourceSurfaceForSurface(mDT, surface);
+
+    if (!surf) {
+      return;
+    }
+
+    Rect rect(0, 0, Float(size.width), Float(size.height));
+    rect.Intersect(Rect(0, 0, Float(surf->GetSize().width), Float(surf->GetSize().height)));
+
+    // XXX - Should fix pixel snapping.
+    mDT->DrawSurface(surf, rect, rect);
+  }
+}
+
+// transform stuff
+void
+gfxContext::Translate(const gfxPoint& pt)
+{
+  if (mCairo) {
+    cairo_translate(mCairo, pt.x, pt.y);
+  } else {
+    Matrix newMatrix = mTransform;
+
+    ChangeTransform(newMatrix.Translate(Float(pt.x), Float(pt.y)));
+  }
+}
+
+void
+gfxContext::Scale(gfxFloat x, gfxFloat y)
+{
+  if (mCairo) {
+    cairo_scale(mCairo, x, y);
+  } else {
+    Matrix newMatrix = mTransform;
+
+    ChangeTransform(newMatrix.Scale(Float(x), Float(y)));
+  }
+}
+
+void
+gfxContext::Rotate(gfxFloat angle)
+{
+  if (mCairo) {
+    cairo_rotate(mCairo, angle);
+  } else {
+    Matrix rotation = Matrix::Rotation(Float(angle));
+    ChangeTransform(rotation * mTransform);
+  }
+}
+
+void
+gfxContext::Multiply(const gfxMatrix& matrix)
+{
+  if (mCairo) {
+    const cairo_matrix_t& mat = reinterpret_cast<const cairo_matrix_t&>(matrix);
+    cairo_transform(mCairo, &mat);
+  } else {
+    ChangeTransform(ToMatrix(matrix) * mTransform);
+  }
+}
+
+void
+gfxContext::MultiplyAndNudgeToIntegers(const gfxMatrix& matrix)
+{
+  if (mCairo) {
+    const cairo_matrix_t& mat = reinterpret_cast<const cairo_matrix_t&>(matrix);
+    cairo_transform(mCairo, &mat);
+    // XXX nudging to integers not currently supported for Thebes
+  } else {
+    Matrix transform = ToMatrix(matrix) * mTransform;
+    transform.NudgeToIntegers();
+    ChangeTransform(transform);
+  }
+}
+
+void
+gfxContext::SetMatrix(const gfxMatrix& matrix)
+{
+  if (mCairo) {
+    const cairo_matrix_t& mat = reinterpret_cast<const cairo_matrix_t&>(matrix);
+    cairo_set_matrix(mCairo, &mat);
+  } else {
+    ChangeTransform(ToMatrix(matrix));
+  }
+}
+
+void
+gfxContext::IdentityMatrix()
+{
+  if (mCairo) {
+    cairo_identity_matrix(mCairo);
+  } else {
+    ChangeTransform(Matrix());
+  }
+}
+
+gfxMatrix
+gfxContext::CurrentMatrix() const
+{
+  if (mCairo) {
+    cairo_matrix_t mat;
+    cairo_get_matrix(mCairo, &mat);
+    return gfxMatrix(*reinterpret_cast<gfxMatrix*>(&mat));
+  } else {
+    return ThebesMatrix(mTransform);
+  }
+}
+
+void
+gfxContext::NudgeCurrentMatrixToIntegers()
+{
+  if (mCairo) {
+    cairo_matrix_t mat;
+    cairo_get_matrix(mCairo, &mat);
+    gfxMatrix(*reinterpret_cast<gfxMatrix*>(&mat)).NudgeToIntegers();
+    cairo_set_matrix(mCairo, &mat);
+  } else {
+    gfxMatrix matrix = ThebesMatrix(mTransform);
+    matrix.NudgeToIntegers();
+    ChangeTransform(ToMatrix(matrix));
+  }
+}
+
+gfxPoint
+gfxContext::DeviceToUser(const gfxPoint& point) const
+{
+  if (mCairo) {
+    gfxPoint ret = point;
+    cairo_device_to_user(mCairo, &ret.x, &ret.y);
+    return ret;
+  } else {
+    Matrix matrix = mTransform;
+
+    matrix.Invert();
+
+    return ThebesPoint(matrix * ToPoint(point));
+  }
+}
+
+gfxSize
+gfxContext::DeviceToUser(const gfxSize& size) const
+{
+  if (mCairo) {
+    gfxSize ret = size;
+    cairo_device_to_user_distance(mCairo, &ret.width, &ret.height);
+    return ret;
+  } else {
+    Matrix matrix = mTransform;
+
+    matrix.Invert();
+
+    return ThebesSize(matrix * ToSize(size));
+  }
+}
+
+gfxRect
+gfxContext::DeviceToUser(const gfxRect& rect) const
+{
+  if (mCairo) {
+    gfxRect ret = rect;
+    cairo_device_to_user(mCairo, &ret.x, &ret.y);
+    cairo_device_to_user_distance(mCairo, &ret.width, &ret.height);
+    return ret;
+  } else {
+    Matrix matrix = mTransform;
+
+    matrix.Invert();
+
+    return ThebesRect(matrix.TransformBounds(ToRect(rect)));
+  }
+}
+
+gfxPoint
+gfxContext::UserToDevice(const gfxPoint& point) const
+{
+  if (mCairo) {
+    gfxPoint ret = point;
+    cairo_user_to_device(mCairo, &ret.x, &ret.y);
+    return ret;
+  } else {
+    return ThebesPoint(mTransform * ToPoint(point));
+  }
+}
+
+gfxSize
+gfxContext::UserToDevice(const gfxSize& size) const
+{
+  if (mCairo) {
+    gfxSize ret = size;
+    cairo_user_to_device_distance(mCairo, &ret.width, &ret.height);
+    return ret;
+  } else {
+    const Matrix &matrix = mTransform;
+
+    gfxSize newSize;
+    newSize.width = size.width * matrix._11 + size.height * matrix._12;
+    newSize.height = size.width * matrix._21 + size.height * matrix._22;
+    return newSize;
+  }
+}
+
+gfxRect
+gfxContext::UserToDevice(const gfxRect& rect) const
+{
+  if (mCairo) {
+    double xmin = rect.X(), ymin = rect.Y(), xmax = rect.XMost(), ymax = rect.YMost();
+
+    double x[3], y[3];
+    x[0] = xmin;  y[0] = ymax;
+    x[1] = xmax;  y[1] = ymax;
+    x[2] = xmax;  y[2] = ymin;
+
+    cairo_user_to_device(mCairo, &xmin, &ymin);
+    xmax = xmin;
+    ymax = ymin;
+    for (int i = 0; i < 3; i++) {
+        cairo_user_to_device(mCairo, &x[i], &y[i]);
+        xmin = std::min(xmin, x[i]);
+        xmax = std::max(xmax, x[i]);
+        ymin = std::min(ymin, y[i]);
+        ymax = std::max(ymax, y[i]);
+    }
+
+    return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
+  } else {
+    const Matrix &matrix = mTransform;
+    return ThebesRect(matrix.TransformBounds(ToRect(rect)));
+  }
+}
+
+bool
+gfxContext::UserToDevicePixelSnapped(gfxRect& rect, bool ignoreScale) const
+{
+  if (GetFlags() & FLAG_DISABLE_SNAPPING)
+      return false;
+
+  // if we're not at 1.0 scale, don't snap, unless we're
+  // ignoring the scale.  If we're not -just- a scale,
+  // never snap.
+  const gfxFloat epsilon = 0.0000001;
+#define WITHIN_E(a,b) (fabs((a)-(b)) < epsilon)
+  if (mCairo) {
+    cairo_matrix_t mat;
+    cairo_get_matrix(mCairo, &mat);
+    if (!ignoreScale &&
+        (!WITHIN_E(mat.xx,1.0) || !WITHIN_E(mat.yy,1.0) ||
+          !WITHIN_E(mat.xy,0.0) || !WITHIN_E(mat.yx,0.0)))
+        return false;
+  } else {
+    Matrix mat = mTransform;
+    if (!ignoreScale &&
+        (!WITHIN_E(mat._11,1.0) || !WITHIN_E(mat._22,1.0) ||
+          !WITHIN_E(mat._12,0.0) || !WITHIN_E(mat._21,0.0)))
+        return false;
+  }
+#undef WITHIN_E
+
+  gfxPoint p1 = UserToDevice(rect.TopLeft());
+  gfxPoint p2 = UserToDevice(rect.TopRight());
+  gfxPoint p3 = UserToDevice(rect.BottomRight());
+
+  // Check that the rectangle is axis-aligned. For an axis-aligned rectangle,
+  // two opposite corners define the entire rectangle. So check if
+  // the axis-aligned rectangle with opposite corners p1 and p3
+  // define an axis-aligned rectangle whose other corners are p2 and p4.
+  // We actually only need to check one of p2 and p4, since an affine
+  // transform maps parallelograms to parallelograms.
+  if (p2 == gfxPoint(p1.x, p3.y) || p2 == gfxPoint(p3.x, p1.y)) {
+      p1.Round();
+      p3.Round();
+
+      rect.MoveTo(gfxPoint(std::min(p1.x, p3.x), std::min(p1.y, p3.y)));
+      rect.SizeTo(gfxSize(std::max(p1.x, p3.x) - rect.X(),
+                          std::max(p1.y, p3.y) - rect.Y()));
+      return true;
+  }
+
+  return false;
+}
+
+bool
+gfxContext::UserToDevicePixelSnapped(gfxPoint& pt, bool ignoreScale) const
+{
+  if (GetFlags() & FLAG_DISABLE_SNAPPING)
+      return false;
+
+  // if we're not at 1.0 scale, don't snap, unless we're
+  // ignoring the scale.  If we're not -just- a scale,
+  // never snap.
+  const gfxFloat epsilon = 0.0000001;
+#define WITHIN_E(a,b) (fabs((a)-(b)) < epsilon)
+  if (mCairo) {
+    cairo_matrix_t mat;
+    cairo_get_matrix(mCairo, &mat);
+    if (!ignoreScale &&
+        (!WITHIN_E(mat.xx,1.0) || !WITHIN_E(mat.yy,1.0) ||
+          !WITHIN_E(mat.xy,0.0) || !WITHIN_E(mat.yx,0.0)))
+        return false;
+  } else {
+    Matrix mat = mTransform;
+    if (!ignoreScale &&
+        (!WITHIN_E(mat._11,1.0) || !WITHIN_E(mat._22,1.0) ||
+          !WITHIN_E(mat._12,0.0) || !WITHIN_E(mat._21,0.0)))
+        return false;
+  }
+#undef WITHIN_E
+
+  pt = UserToDevice(pt);
+  pt.Round();
+  return true;
+}
+
+void
+gfxContext::PixelSnappedRectangleAndSetPattern(const gfxRect& rect,
+                                               gfxPattern *pattern)
+{
+  gfxRect r(rect);
+
+  // Bob attempts to pixel-snap the rectangle, and returns true if
+  // the snapping succeeds.  If it does, we need to set up an
+  // identity matrix, because the rectangle given back is in device
+  // coordinates.
+  //
+  // We then have to call a translate to dr.pos afterwards, to make
+  // sure the image lines up in the right place with our pixel
+  // snapped rectangle.
+  //
+  // If snapping wasn't successful, we just translate to where the
+  // pattern would normally start (in app coordinates) and do the
+  // same thing.
+  Rectangle(r, true);
+  SetPattern(pattern);
+}
+
+void
+gfxContext::SetAntialiasMode(AntialiasMode mode)
+{
+  if (mCairo) {
+    if (mode == MODE_ALIASED) {
+        cairo_set_antialias(mCairo, CAIRO_ANTIALIAS_NONE);
+    } else if (mode == MODE_COVERAGE) {
+        cairo_set_antialias(mCairo, CAIRO_ANTIALIAS_DEFAULT);
+    }
+  } else {
+    if (mode == MODE_ALIASED) {
+      CurrentState().aaMode = gfx::AntialiasMode::NONE;
+    } else if (mode == MODE_COVERAGE) {
+      CurrentState().aaMode = gfx::AntialiasMode::SUBPIXEL;
+    }
+  }
+}
+
+gfxContext::AntialiasMode
+gfxContext::CurrentAntialiasMode() const
+{
+  if (mCairo) {
+    cairo_antialias_t aa = cairo_get_antialias(mCairo);
+    if (aa == CAIRO_ANTIALIAS_NONE)
+        return MODE_ALIASED;
+    return MODE_COVERAGE;
+  } else {
+    if (CurrentState().aaMode == gfx::AntialiasMode::NONE) {
+      return MODE_ALIASED;
+    }
+    return MODE_COVERAGE;
+  }
+}
+
+void
+gfxContext::SetDash(gfxLineType ltype)
+{
+  static double dash[] = {5.0, 5.0};
+  static double dot[] = {1.0, 1.0};
+
+  switch (ltype) {
+      case gfxLineDashed:
+          SetDash(dash, 2, 0.0);
+          break;
+      case gfxLineDotted:
+          SetDash(dot, 2, 0.0);
+          break;
+      case gfxLineSolid:
+      default:
+          SetDash(nullptr, 0, 0.0);
+          break;
+  }
+}
+
+void
+gfxContext::SetDash(gfxFloat *dashes, int ndash, gfxFloat offset)
+{
+  if (mCairo) {
+    cairo_set_dash(mCairo, dashes, ndash, offset);
+  } else {
+    AzureState &state = CurrentState();
+
+    state.dashPattern.SetLength(ndash);
+    for (int i = 0; i < ndash; i++) {
+      state.dashPattern[i] = Float(dashes[i]);
+    }
+    state.strokeOptions.mDashLength = ndash;
+    state.strokeOptions.mDashOffset = Float(offset);
+    state.strokeOptions.mDashPattern = ndash ? state.dashPattern.Elements()
+                                             : nullptr;
+  }
+}
+
+bool
+gfxContext::CurrentDash(FallibleTArray<gfxFloat>& dashes, gfxFloat* offset) const
+{
+  if (mCairo) {
+    int count = cairo_get_dash_count(mCairo);
+    if (count <= 0 || !dashes.SetLength(count)) {
+        return false;
+    }
+    cairo_get_dash(mCairo, dashes.Elements(), offset);
+    return true;
+  } else {
+    const AzureState &state = CurrentState();
+    int count = state.strokeOptions.mDashLength;
+
+    if (count <= 0 || !dashes.SetLength(count)) {
+      return false;
+    }
+
+    for (int i = 0; i < count; i++) {
+      dashes[i] = state.dashPattern[i];
+    }
+
+    *offset = state.strokeOptions.mDashOffset;
+
+    return true;
+  }
+}
+
+gfxFloat
+gfxContext::CurrentDashOffset() const
+{
+  if (mCairo) {
+    if (cairo_get_dash_count(mCairo) <= 0) {
+        return 0.0;
+    }
+    gfxFloat offset;
+    cairo_get_dash(mCairo, nullptr, &offset);
+    return offset;
+  } else {
+    return CurrentState().strokeOptions.mDashOffset;
+  }
+}
+
+void
+gfxContext::SetLineWidth(gfxFloat width)
+{
+  if (mCairo) {
+    cairo_set_line_width(mCairo, width);
+  } else {
+    CurrentState().strokeOptions.mLineWidth = Float(width);
+  }
+}
+
+gfxFloat
+gfxContext::CurrentLineWidth() const
+{
+  if (mCairo) {
+    return cairo_get_line_width(mCairo);
+  } else {
+    return CurrentState().strokeOptions.mLineWidth;
+  }
+}
+
+void
+gfxContext::SetOperator(GraphicsOperator op)
+{
+  if (mCairo) {
+    if (mFlags & FLAG_SIMPLIFY_OPERATORS) {
+        if (op != OPERATOR_SOURCE &&
+            op != OPERATOR_CLEAR &&
+            op != OPERATOR_OVER)
+            op = OPERATOR_OVER;
+    }
+
+    cairo_set_operator(mCairo, (cairo_operator_t)op);
+  } else {
+    if (op == OPERATOR_CLEAR) {
+      CurrentState().opIsClear = true;
+      return;
+    }
+    CurrentState().opIsClear = false;
+    CurrentState().op = CompositionOpForOp(op);
+  }
+}
+
+gfxContext::GraphicsOperator
+gfxContext::CurrentOperator() const
+{
+  if (mCairo) {
+    return (GraphicsOperator)cairo_get_operator(mCairo);
+  } else {
+    return ThebesOp(CurrentState().op);
+  }
+}
+
+void
+gfxContext::SetLineCap(GraphicsLineCap cap)
+{
+  if (mCairo) {
+    cairo_set_line_cap(mCairo, (cairo_line_cap_t)cap);
+  } else {
+    CurrentState().strokeOptions.mLineCap = ToCapStyle(cap);
+  }
+}
+
+gfxContext::GraphicsLineCap
+gfxContext::CurrentLineCap() const
+{
+  if (mCairo) {
+    return (GraphicsLineCap)cairo_get_line_cap(mCairo);
+  } else {
+    return ThebesLineCap(CurrentState().strokeOptions.mLineCap);
+  }
+}
+
+void
+gfxContext::SetLineJoin(GraphicsLineJoin join)
+{
+  if (mCairo) {
+    cairo_set_line_join(mCairo, (cairo_line_join_t)join);
+  } else {
+    CurrentState().strokeOptions.mLineJoin = ToJoinStyle(join);
+  }
+}
+
+gfxContext::GraphicsLineJoin
+gfxContext::CurrentLineJoin() const
+{
+  if (mCairo) {
+    return (GraphicsLineJoin)cairo_get_line_join(mCairo);
+  } else {
+    return ThebesLineJoin(CurrentState().strokeOptions.mLineJoin);
+  }
+}
+
+void
+gfxContext::SetMiterLimit(gfxFloat limit)
+{
+  if (mCairo) {
+    cairo_set_miter_limit(mCairo, limit);
+  } else {
+    CurrentState().strokeOptions.mMiterLimit = Float(limit);
+  }
+}
+
+gfxFloat
+gfxContext::CurrentMiterLimit() const
+{
+  if (mCairo) {
+    return cairo_get_miter_limit(mCairo);
+  } else {
+    return CurrentState().strokeOptions.mMiterLimit;
+  }
+}
+
+void
+gfxContext::SetFillRule(FillRule rule)
+{
+  if (mCairo) {
+    cairo_set_fill_rule(mCairo, (cairo_fill_rule_t)rule);
+  } else {
+    CurrentState().fillRule = rule == FILL_RULE_WINDING ? gfx::FillRule::FILL_WINDING : gfx::FillRule::FILL_EVEN_ODD;
+  }
+}
+
+gfxContext::FillRule
+gfxContext::CurrentFillRule() const
+{
+  if (mCairo) {
+    return (FillRule)cairo_get_fill_rule(mCairo);
+  } else {
+    return FILL_RULE_WINDING;
+  }
+}
+
+// clipping
+void
+gfxContext::Clip(const gfxRect& rect)
+{
+  if (mCairo) {
+    cairo_new_path(mCairo);
+    cairo_rectangle(mCairo, rect.X(), rect.Y(), rect.Width(), rect.Height());
+    cairo_clip(mCairo);
+  } else {
+    AzureState::PushedClip clip = { nullptr, ToRect(rect), mTransform };
+    CurrentState().pushedClips.AppendElement(clip);
+    mDT->PushClipRect(ToRect(rect));
+    NewPath();
+  }
+}
+
+void
+gfxContext::Clip()
+{
+  if (mCairo) {
+    cairo_clip_preserve(mCairo);
+  } else {
+    if (mPathIsRect) {
+      MOZ_ASSERT(!mTransformChanged);
+
+      AzureState::PushedClip clip = { nullptr, mRect, mTransform };
+      CurrentState().pushedClips.AppendElement(clip);
+      mDT->PushClipRect(mRect);
+    } else {
+      EnsurePath();
+      mDT->PushClip(mPath);
+      AzureState::PushedClip clip = { mPath, Rect(), mTransform };
+      CurrentState().pushedClips.AppendElement(clip);
+    }
+  }
+}
+
+void
+gfxContext::ResetClip()
+{
+  if (mCairo) {
+    cairo_reset_clip(mCairo);
+  } else {
+    for (int i = mStateStack.Length() - 1; i >= 0; i--) {
+      for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
+        mDT->PopClip();
+      }
+
+      if (mStateStack[i].clipWasReset) {
+        break;
+      }
+    }
+    CurrentState().pushedClips.Clear();
+    CurrentState().clipWasReset = true;
+  }
+}
+
+void
+gfxContext::UpdateSurfaceClip()
+{
+  if (mCairo) {
+    NewPath();
+    // we paint an empty rectangle to ensure the clip is propagated to
+    // the destination surface
+    SetDeviceColor(gfxRGBA(0,0,0,0));
+    Rectangle(gfxRect(0,1,1,0));
+    Fill();
+  }
+}
+
+gfxRect
+gfxContext::GetClipExtents()
+{
+  if (mCairo) {
+    double xmin, ymin, xmax, ymax;
+    cairo_clip_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
+    return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
+  } else {
+    Rect rect = GetAzureDeviceSpaceClipBounds();
+
+    if (rect.width == 0 || rect.height == 0) {
+      return gfxRect(0, 0, 0, 0);
+    }
+
+    Matrix mat = mTransform;
+    mat.Invert();
+    rect = mat.TransformBounds(rect);
+
+    return ThebesRect(rect);
+  }
+}
+
+bool
+gfxContext::ClipContainsRect(const gfxRect& aRect)
+{
+  if (mCairo) {
+    cairo_rectangle_list_t *clip =
+        cairo_copy_clip_rectangle_list(mCairo);
+
+    bool result = false;
+
+    if (clip->status == CAIRO_STATUS_SUCCESS) {
+        for (int i = 0; i < clip->num_rectangles; i++) {
+            gfxRect rect(clip->rectangles[i].x, clip->rectangles[i].y,
+                         clip->rectangles[i].width, clip->rectangles[i].height);
+            if (rect.Contains(aRect)) {
+                result = true;
+                break;
+            }
+        }
+    }
+
+    cairo_rectangle_list_destroy(clip);
+    return result;
+  } else {
+    unsigned int lastReset = 0;
+    for (int i = mStateStack.Length() - 2; i > 0; i--) {
+      if (mStateStack[i].clipWasReset) {
+        lastReset = i;
+        break;
+      }
+    }
+
+    // Since we always return false when the clip list contains a
+    // non-rectangular clip or a non-rectilinear transform, our 'total' clip
+    // is always a rectangle if we hit the end of this function.
+    Rect clipBounds(0, 0, Float(mDT->GetSize().width), Float(mDT->GetSize().height));
+
+    for (unsigned int i = lastReset; i < mStateStack.Length(); i++) {
+      for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
+        AzureState::PushedClip &clip = mStateStack[i].pushedClips[c];
+        if (clip.path || !clip.transform.IsRectilinear()) {
+          // Cairo behavior is we return false if the clip contains a non-
+          // rectangle.
+          return false;
+        } else {
+          Rect clipRect = mTransform.TransformBounds(clip.rect);
+
+          clipBounds.IntersectRect(clipBounds, clipRect);
+        }
+      }
+    }
+
+    return clipBounds.Contains(ToRect(aRect));
+  }
+}
+
+// rendering sources
+
+void
+gfxContext::SetColor(const gfxRGBA& c)
+{
+  if (mCairo) {
+    if (gfxPlatform::GetCMSMode() == eCMSMode_All) {
+
+        gfxRGBA cms;
+        qcms_transform *transform = gfxPlatform::GetCMSRGBTransform();
+        if (transform)
+          gfxPlatform::TransformPixel(c, cms, transform);
+
+        // Use the original alpha to avoid unnecessary float->byte->float
+        // conversion errors
+        cairo_set_source_rgba(mCairo, cms.r, cms.g, cms.b, c.a);
+    }
+    else
+        cairo_set_source_rgba(mCairo, c.r, c.g, c.b, c.a);
+  } else {
+    CurrentState().pattern = nullptr;
+    CurrentState().sourceSurfCairo = nullptr;
+    CurrentState().sourceSurface = nullptr;
+
+    if (gfxPlatform::GetCMSMode() == eCMSMode_All) {
+
+        gfxRGBA cms;
+        qcms_transform *transform = gfxPlatform::GetCMSRGBTransform();
+        if (transform)
+          gfxPlatform::TransformPixel(c, cms, transform);
+
+        // Use the original alpha to avoid unnecessary float->byte->float
+        // conversion errors
+        CurrentState().color = ToColor(cms);
+    }
+    else
+        CurrentState().color = ToColor(c);
+  }
+}
+
+void
+gfxContext::SetDeviceColor(const gfxRGBA& c)
+{
+  if (mCairo) {
+    cairo_set_source_rgba(mCairo, c.r, c.g, c.b, c.a);
+  } else {
+    CurrentState().pattern = nullptr;
+    CurrentState().sourceSurfCairo = nullptr;
+    CurrentState().sourceSurface = nullptr;
+    CurrentState().color = ToColor(c);
+  }
+}
+
+bool
+gfxContext::GetDeviceColor(gfxRGBA& c)
+{
+  if (mCairo) {
+    return cairo_pattern_get_rgba(cairo_get_source(mCairo),
+                                  &c.r,
+                                  &c.g,
+                                  &c.b,
+                                  &c.a) == CAIRO_STATUS_SUCCESS;
+  } else {
+    if (CurrentState().sourceSurface) {
+      return false;
+    }
+    if (CurrentState().pattern) {
+      gfxRGBA color;
+      return CurrentState().pattern->GetSolidColor(c);
+    }
+
+    c = ThebesRGBA(CurrentState().color);
+    return true;
+  }
+}
+
+void
+gfxContext::SetSource(gfxASurface *surface, const gfxPoint& offset)
+{
+  if (mCairo) {
+    NS_ASSERTION(surface->GetAllowUseAsSource(), "Surface not allowed to be used as source!");
+    cairo_set_source_surface(mCairo, surface->CairoSurface(), offset.x, offset.y);
+  } else {
+    CurrentState().surfTransform = Matrix(1.0f, 0, 0, 1.0f, Float(offset.x), Float(offset.y));
+    CurrentState().pattern = nullptr;
+    CurrentState().patternTransformChanged = false;
+    // Keep the underlying cairo surface around while we keep the
+    // sourceSurface.
+    CurrentState().sourceSurfCairo = surface;
+    CurrentState().sourceSurface =
+      gfxPlatform::GetPlatform()->GetSourceSurfaceForSurface(mDT, surface);
+    CurrentState().color = Color(0, 0, 0, 0);
+  }
+}
+
+void
+gfxContext::SetPattern(gfxPattern *pattern)
+{
+  if (mCairo) {
+    MOZ_ASSERT(!pattern->IsAzure());
+    cairo_set_source(mCairo, pattern->CairoPattern());
+  } else {
+    CurrentState().sourceSurfCairo = nullptr;
+    CurrentState().sourceSurface = nullptr;
+    CurrentState().patternTransformChanged = false;
+    CurrentState().pattern = pattern;
+  }
+}
+
+already_AddRefed<gfxPattern>
+gfxContext::GetPattern()
+{
+  if (mCairo) {
+    cairo_pattern_t *pat = cairo_get_source(mCairo);
+    NS_ASSERTION(pat, "I was told this couldn't be null");
+
+    nsRefPtr<gfxPattern> wrapper;
+    if (pat)
+        wrapper = new gfxPattern(pat);
+    else
+        wrapper = new gfxPattern(gfxRGBA(0,0,0,0));
+
+    return wrapper.forget();
+  } else {
+    nsRefPtr<gfxPattern> pat;
+    
+    AzureState &state = CurrentState();
+    if (state.pattern) {
+      pat = state.pattern;
+    } else if (state.sourceSurface) {
+      NS_ASSERTION(false, "Ugh, this isn't good.");
+    } else {
+      pat = new gfxPattern(ThebesRGBA(state.color));
+    }
+    return pat.forget();
+  }
+}
+
+
+// masking
+void
+gfxContext::Mask(gfxPattern *pattern)
+{
+  if (mCairo) {
+    MOZ_ASSERT(!pattern->IsAzure());
+    cairo_mask(mCairo, pattern->CairoPattern());
+  } else {
+    if (pattern->Extend() == gfxPattern::EXTEND_NONE) {
+      // In this situation the mask will be fully transparent (i.e. nothing
+      // will be drawn) outside of the bounds of the surface. We can support
+      // that by clipping out drawing to that area.
+      Point offset;
+      if (pattern->IsAzure()) {
+        // This is an Azure pattern. i.e. this was the result of a PopGroup and
+        // then the extend mode was changed to EXTEND_NONE.
+        // XXX - We may need some additional magic here in theory to support
+        // device offsets in these patterns, but no problems have been observed
+        // yet because of this. And it would complicate things a little further.
+        offset = Point(0.f, 0.f);
+      } else if (pattern->GetType() == gfxPattern::PATTERN_SURFACE) {
+        nsRefPtr<gfxASurface> asurf = pattern->GetSurface();
+        gfxPoint deviceOffset = asurf->GetDeviceOffset();
+        offset = Point(-deviceOffset.x, -deviceOffset.y);
+
+        // this lets GetAzureSurface work
+        pattern->GetPattern(mDT);
+      }
+
+      if (pattern->IsAzure() || pattern->GetType() == gfxPattern::PATTERN_SURFACE) {
+        RefPtr<SourceSurface> mask = pattern->GetAzureSurface();
+        Matrix mat = ToMatrix(pattern->GetInverseMatrix());
+        Matrix old = mTransform;
+        // add in the inverse of the pattern transform so that when we
+        // MaskSurface we are transformed to the place matching the pattern transform
+        mat = mat * mTransform;
+
+        ChangeTransform(mat);
+        mDT->MaskSurface(GeneralPattern(this), mask, offset, DrawOptions(1.0f, CurrentState().op, CurrentState().aaMode));
+        ChangeTransform(old);
+        return;
+      }
+    }
+    mDT->Mask(GeneralPattern(this), *pattern->GetPattern(mDT), DrawOptions(1.0f, CurrentState().op, CurrentState().aaMode));
+  }
+}
+
+void
+gfxContext::Mask(gfxASurface *surface, const gfxPoint& offset)
+{
+  PROFILER_LABEL("gfxContext", "Mask");
+  if (mCairo) {
+    cairo_mask_surface(mCairo, surface->CairoSurface(), offset.x, offset.y);
+  } else {
+    // Lifetime needs to be limited here as we may simply wrap surface's data.
+    RefPtr<SourceSurface> sourceSurf =
+      gfxPlatform::GetPlatform()->GetSourceSurfaceForSurface(mDT, surface);
+
+    if (!sourceSurf) {
+      return;
+    }
+
+    gfxPoint pt = surface->GetDeviceOffset();
+
+    Mask(sourceSurf, Point(offset.x - pt.x, offset.y - pt.y));
+  }
+}
+
+void
+gfxContext::Mask(SourceSurface *surface, const Point& offset)
+{
+  MOZ_ASSERT(mDT);
+
+
+  // We clip here to bind to the mask surface bounds, see above.
+  mDT->MaskSurface(GeneralPattern(this),
+            surface,
+            offset,
+            DrawOptions(1.0f, CurrentState().op, CurrentState().aaMode));
+}
+
+void
+gfxContext::Paint(gfxFloat alpha)
+{
+  PROFILER_LABEL("gfxContext", "Paint");
+  if (mCairo) {
+    cairo_paint_with_alpha(mCairo, alpha);
+  } else {
+    AzureState &state = CurrentState();
+
+    if (state.sourceSurface && !state.sourceSurfCairo &&
+        !state.patternTransformChanged && !state.opIsClear)
+    {
+      // This is the case where a PopGroupToSource has been done and this
+      // paint is executed without changing the transform or the source.
+      Matrix oldMat = mDT->GetTransform();
+
+      IntSize surfSize = state.sourceSurface->GetSize();
+
+      Matrix mat;
+      mat.Translate(-state.deviceOffset.x, -state.deviceOffset.y);
+      mDT->SetTransform(mat);
+
+      mDT->DrawSurface(state.sourceSurface,
+                       Rect(state.sourceSurfaceDeviceOffset, Size(surfSize.width, surfSize.height)),
+                       Rect(Point(), Size(surfSize.width, surfSize.height)),
+                       DrawSurfaceOptions(), DrawOptions(alpha, GetOp()));
+      mDT->SetTransform(oldMat);
+      return;
+    }
+
+    Matrix mat = mDT->GetTransform();
+    mat.Invert();
+    Rect paintRect = mat.TransformBounds(Rect(Point(0, 0), Size(mDT->GetSize())));
+
+    if (state.opIsClear) {
+      mDT->ClearRect(paintRect);
+    } else {
+      mDT->FillRect(paintRect, GeneralPattern(this),
+                    DrawOptions(Float(alpha), GetOp()));
+    }
+  }
+}
+
+// groups
+
+void
+gfxContext::PushGroup(gfxContentType content)
+{
+  if (mCairo) {
+    cairo_push_group_with_content(mCairo, (cairo_content_t)(int) content);
+  } else {
+    PushNewDT(content);
+
+    PushClipsToDT(mDT);
+    mDT->SetTransform(GetDTTransform());
+  }
+}
+
+static gfxRect
+GetRoundOutDeviceClipExtents(gfxContext* aCtx)
+{
+  gfxContextMatrixAutoSaveRestore save(aCtx);
+  aCtx->IdentityMatrix();
+  gfxRect r = aCtx->GetClipExtents();
+  r.RoundOut();
+  return r;
+}
+
+/**
+ * Copy the contents of aSrc to aDest, translated by aTranslation.
+ */
+static void
+CopySurface(gfxASurface* aSrc, gfxASurface* aDest, const gfxPoint& aTranslation)
+{
+  cairo_t *cr = cairo_create(aDest->CairoSurface());
+  cairo_set_source_surface(cr, aSrc->CairoSurface(), aTranslation.x, aTranslation.y);
+  cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+  cairo_paint(cr);
+  cairo_destroy(cr);
+}
+
+void
+gfxContext::PushGroupAndCopyBackground(gfxContentType content)
+{
+  if (mCairo) {
+    if (content == gfxContentType::COLOR_ALPHA &&
+      !(GetFlags() & FLAG_DISABLE_COPY_BACKGROUND)) {
+      nsRefPtr<gfxASurface> s = CurrentSurface();
+      if ((s->GetAllowUseAsSource() || s->GetType() == gfxSurfaceType::Tee) &&
+          (s->GetContentType() == gfxContentType::COLOR ||
+              s->GetOpaqueRect().Contains(GetRoundOutDeviceClipExtents(this)))) {
+        cairo_push_group_with_content(mCairo, CAIRO_CONTENT_COLOR);
+        nsRefPtr<gfxASurface> d = CurrentSurface();
+
+        if (d->GetType() == gfxSurfaceType::Tee) {
+          NS_ASSERTION(s->GetType() == gfxSurfaceType::Tee, "Mismatched types");
+          nsAutoTArray<nsRefPtr<gfxASurface>,2> ss;
+          nsAutoTArray<nsRefPtr<gfxASurface>,2> ds;
+          static_cast<gfxTeeSurface*>(s.get())->GetSurfaces(&ss);
+          static_cast<gfxTeeSurface*>(d.get())->GetSurfaces(&ds);
+          NS_ASSERTION(ss.Length() == ds.Length(), "Mismatched lengths");
+          gfxPoint translation = d->GetDeviceOffset() - s->GetDeviceOffset();
+          for (uint32_t i = 0; i < ss.Length(); ++i) {
+              CopySurface(ss[i], ds[i], translation);
+          }
+        } else {
+          CopySurface(s, d, gfxPoint(0, 0));
+        }
+        d->SetOpaqueRect(s->GetOpaqueRect());
+        return;
+      }
+    }
+  } else {
+    IntRect clipExtents;
+    if (mDT->GetFormat() != SurfaceFormat::B8G8R8X8) {
+      gfxRect clipRect = GetRoundOutDeviceClipExtents(this);
+      clipExtents = IntRect(clipRect.x, clipRect.y, clipRect.width, clipRect.height);
+    }
+    if ((mDT->GetFormat() == SurfaceFormat::B8G8R8X8 ||
+         mDT->GetOpaqueRect().Contains(clipExtents)) &&
+        !mDT->GetUserData(&sDontUseAsSourceKey)) {
+      DrawTarget *oldDT = mDT;
+      RefPtr<SourceSurface> source = mDT->Snapshot();
+      Point oldDeviceOffset = CurrentState().deviceOffset;
+
+      PushNewDT(gfxContentType::COLOR);
+
+      Point offset = CurrentState().deviceOffset - oldDeviceOffset;
+      Rect surfRect(0, 0, Float(mDT->GetSize().width), Float(mDT->GetSize().height));
+      Rect sourceRect = surfRect;
+      sourceRect.x += offset.x;
+      sourceRect.y += offset.y;
+
+      mDT->SetTransform(Matrix());
+      mDT->DrawSurface(source, surfRect, sourceRect);
+      mDT->SetOpaqueRect(oldDT->GetOpaqueRect());
+
+      PushClipsToDT(mDT);
+      mDT->SetTransform(GetDTTransform());
+      return;
+    }
+  }
+  PushGroup(content);
+}
+
+already_AddRefed<gfxPattern>
+gfxContext::PopGroup()
+{
+  if (mCairo) {
+    cairo_pattern_t *pat = cairo_pop_group(mCairo);
+    nsRefPtr<gfxPattern> wrapper = new gfxPattern(pat);
+    cairo_pattern_destroy(pat);
+    return wrapper.forget();
+  } else {
+    RefPtr<SourceSurface> src = mDT->Snapshot();
+    Point deviceOffset = CurrentState().deviceOffset;
+
+    Restore();
+
+    Matrix mat = mTransform;
+    mat.Invert();
+
+    Matrix deviceOffsetTranslation;
+    deviceOffsetTranslation.Translate(deviceOffset.x, deviceOffset.y);
+
+    nsRefPtr<gfxPattern> pat = new gfxPattern(src, deviceOffsetTranslation * mat);
+
+    return pat.forget();
+  }
+}
+
+void
+gfxContext::PopGroupToSource()
+{
+  if (mCairo) {
+    cairo_pop_group_to_source(mCairo);
+  } else {
+    RefPtr<SourceSurface> src = mDT->Snapshot();
+    Point deviceOffset = CurrentState().deviceOffset;
+    Restore();
+    CurrentState().sourceSurfCairo = nullptr;
+    CurrentState().sourceSurface = src;
+    CurrentState().sourceSurfaceDeviceOffset = deviceOffset;
+    CurrentState().pattern = nullptr;
+    CurrentState().patternTransformChanged = false;
+
+    Matrix mat = mTransform;
+    mat.Invert();
+
+    Matrix deviceOffsetTranslation;
+    deviceOffsetTranslation.Translate(deviceOffset.x, deviceOffset.y);
+    CurrentState().surfTransform = deviceOffsetTranslation * mat;
+  }
+}
+
+bool
+gfxContext::PointInFill(const gfxPoint& pt)
+{
+  if (mCairo) {
+    return cairo_in_fill(mCairo, pt.x, pt.y);
+  } else {
+    EnsurePath();
+    return mPath->ContainsPoint(ToPoint(pt), Matrix());
+  }
+}
+
+bool
+gfxContext::PointInStroke(const gfxPoint& pt)
+{
+  if (mCairo) {
+    return cairo_in_stroke(mCairo, pt.x, pt.y);
+  } else {
+    EnsurePath();
+    return mPath->StrokeContainsPoint(CurrentState().strokeOptions,
+                                      ToPoint(pt),
+                                      Matrix());
+  }
+}
+
+gfxRect
+gfxContext::GetUserPathExtent()
+{
+  if (mCairo) {
+    double xmin, ymin, xmax, ymax;
+    cairo_path_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
+    return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
+  } else {
+    EnsurePath();
+    return ThebesRect(mPath->GetBounds());
+  }
+}
+
+gfxRect
+gfxContext::GetUserFillExtent()
+{
+  if (mCairo) {
+    double xmin, ymin, xmax, ymax;
+    cairo_fill_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
+    return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
+  } else {
+    EnsurePath();
+    return ThebesRect(mPath->GetBounds());
+  }
+}
+
+gfxRect
+gfxContext::GetUserStrokeExtent()
+{
+  if (mCairo) {
+    double xmin, ymin, xmax, ymax;
+    cairo_stroke_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
+    return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
+  } else {
+    EnsurePath();
+    return ThebesRect(mPath->GetStrokedBounds(CurrentState().strokeOptions, mTransform));
+  }
+}
+
+bool
+gfxContext::HasError()
+{
+  if (mCairo) {
+    return cairo_status(mCairo) != CAIRO_STATUS_SUCCESS;
+  } else {
+    // As far as this is concerned, an Azure context is never in error.
+    return false;
+  }
+}
+
+void
+gfxContext::RoundedRectangle(const gfxRect& rect,
+                             const gfxCornerSizes& corners,
+                             bool draw_clockwise)
+{
+    //
+    // For CW drawing, this looks like:
+    //
+    //  ...******0**      1    C
+    //              ****
+    //                  ***    2
+    //                     **
+    //                       *
+    //                        *
+    //                         3
+    //                         *
+    //                         *
+    //
+    // Where 0, 1, 2, 3 are the control points of the Bezier curve for
+    // the corner, and C is the actual corner point.
+    //
+    // At the start of the loop, the current point is assumed to be
+    // the point adjacent to the top left corner on the top
+    // horizontal.  Note that corner indices start at the top left and
+    // continue clockwise, whereas in our loop i = 0 refers to the top
+    // right corner.
+    //
+    // When going CCW, the control points are swapped, and the first
+    // corner that's drawn is the top left (along with the top segment).
+    //
+    // There is considerable latitude in how one chooses the four
+    // control points for a Bezier curve approximation to an ellipse.
+    // For the overall path to be continuous and show no corner at the
+    // endpoints of the arc, points 0 and 3 must be at the ends of the
+    // straight segments of the rectangle; points 0, 1, and C must be
+    // collinear; and points 3, 2, and C must also be collinear.  This
+    // leaves only two free parameters: the ratio of the line segments
+    // 01 and 0C, and the ratio of the line segments 32 and 3C.  See
+    // the following papers for extensive discussion of how to choose
+    // these ratios:
+    //
+    //   Dokken, Tor, et al. "Good approximation of circles by
+    //      curvature-continuous Bezier curves."  Computer-Aided
+    //      Geometric Design 7(1990) 33--41.
+    //   Goldapp, Michael. "Approximation of circular arcs by cubic
+    //      polynomials." Computer-Aided Geometric Design 8(1991) 227--238.
+    //   Maisonobe, Luc. "Drawing an elliptical arc using polylines,
+    //      quadratic, or cubic Bezier curves."
+    //      http://www.spaceroots.org/documents/ellipse/elliptical-arc.pdf
+    //
+    // We follow the approach in section 2 of Goldapp (least-error,
+    // Hermite-type approximation) and make both ratios equal to
+    //
+    //          2   2 + n - sqrt(2n + 28)
+    //  alpha = - * ---------------------
+    //          3           n - 4
+    //
+    // where n = 3( cbrt(sqrt(2)+1) - cbrt(sqrt(2)-1) ).
+    //
+    // This is the result of Goldapp's equation (10b) when the angle
+    // swept out by the arc is pi/2, and the parameter "a-bar" is the
+    // expression given immediately below equation (21).
+    //
+    // Using this value, the maximum radial error for a circle, as a
+    // fraction of the radius, is on the order of 0.2 x 10^-3.
+    // Neither Dokken nor Goldapp discusses error for a general
+    // ellipse; Maisonobe does, but his choice of control points
+    // follows different constraints, and Goldapp's expression for
+    // 'alpha' gives much smaller radial error, even for very flat
+    // ellipses, than Maisonobe's equivalent.
+    //
+    // For the various corners and for each axis, the sign of this
+    // constant changes, or it might be 0 -- it's multiplied by the
+    // appropriate multiplier from the list before using.
+
+  if (mCairo) {
+    const gfxFloat alpha = 0.55191497064665766025;
+
+    typedef struct { gfxFloat a, b; } twoFloats;
+
+    twoFloats cwCornerMults[4] = { { -1,  0 },
+                                   {  0, -1 },
+                                   { +1,  0 },
+                                   {  0, +1 } };
+    twoFloats ccwCornerMults[4] = { { +1,  0 },
+                                    {  0, -1 },
+                                    { -1,  0 },
+                                    {  0, +1 } };
+
+    twoFloats *cornerMults = draw_clockwise ? cwCornerMults : ccwCornerMults;
+
+    gfxPoint pc, p0, p1, p2, p3;
+
+    if (draw_clockwise)
+        cairo_move_to(mCairo, rect.X() + corners[NS_CORNER_TOP_LEFT].width, rect.Y());
+    else
+        cairo_move_to(mCairo, rect.X() + rect.Width() - corners[NS_CORNER_TOP_RIGHT].width, rect.Y());
+
+    NS_FOR_CSS_CORNERS(i) {
+        // the corner index -- either 1 2 3 0 (cw) or 0 3 2 1 (ccw)
+        mozilla::css::Corner c = mozilla::css::Corner(draw_clockwise ? ((i+1) % 4) : ((4-i) % 4));
+
+        // i+2 and i+3 respectively.  These are used to index into the corner
+        // multiplier table, and were deduced by calculating out the long form
+        // of each corner and finding a pattern in the signs and values.
+        int i2 = (i+2) % 4;
+        int i3 = (i+3) % 4;
+
+        pc = rect.AtCorner(c);
+
+        if (corners[c].width > 0.0 && corners[c].height > 0.0) {
+            p0.x = pc.x + cornerMults[i].a * corners[c].width;
+            p0.y = pc.y + cornerMults[i].b * corners[c].height;
+
+            p3.x = pc.x + cornerMults[i3].a * corners[c].width;
+            p3.y = pc.y + cornerMults[i3].b * corners[c].height;
+
+            p1.x = p0.x + alpha * cornerMults[i2].a * corners[c].width;
+            p1.y = p0.y + alpha * cornerMults[i2].b * corners[c].height;
+
+            p2.x = p3.x - alpha * cornerMults[i3].a * corners[c].width;
+            p2.y = p3.y - alpha * cornerMults[i3].b * corners[c].height;
+
+            cairo_line_to (mCairo, p0.x, p0.y);
+            cairo_curve_to (mCairo,
+                            p1.x, p1.y,
+                            p2.x, p2.y,
+                            p3.x, p3.y);
+        } else {
+            cairo_line_to (mCairo, pc.x, pc.y);
+        }
+    }
+
+    cairo_close_path (mCairo);
+  } else {
+    EnsurePathBuilder();
+    Size radii[] = { ToSize(corners[NS_CORNER_TOP_LEFT]),
+                     ToSize(corners[NS_CORNER_TOP_RIGHT]),
+                     ToSize(corners[NS_CORNER_BOTTOM_RIGHT]),
+                     ToSize(corners[NS_CORNER_BOTTOM_LEFT]) };
+    AppendRoundedRectToPath(mPathBuilder, ToRect(rect), radii, draw_clockwise);
+  }
+}
+
+#ifdef MOZ_DUMP_PAINTING
+void
+gfxContext::WriteAsPNG(const char* aFile)
+{ 
+  nsRefPtr<gfxASurface> surf = CurrentSurface();
+  if (surf) {
+    surf->WriteAsPNG(aFile);
+  } else {
+    NS_WARNING("No surface found!");
+  }
+}
+
+void 
+gfxContext::DumpAsDataURL()
+{ 
+  nsRefPtr<gfxASurface> surf = CurrentSurface();
+  if (surf) {
+    surf->DumpAsDataURL();
+  } else {
+    NS_WARNING("No surface found!");
+  }
+}
+
+void 
+gfxContext::CopyAsDataURL()
+{ 
+  nsRefPtr<gfxASurface> surf = CurrentSurface();
+  if (surf) {
+    surf->CopyAsDataURL();
+  } else {
+    NS_WARNING("No surface found!");
+  }
+}
+#endif
+
+void
+gfxContext::EnsurePath()
+{
+  if (mPathBuilder) {
+    mPath = mPathBuilder->Finish();
+    mPathBuilder = nullptr;
+  }
+
+  if (mPath) {
+    if (mTransformChanged) {
+      Matrix mat = mTransform;
+      mat.Invert();
+      mat = mPathTransform * mat;
+      mPathBuilder = mPath->TransformedCopyToBuilder(mat, CurrentState().fillRule);
+      mPath = mPathBuilder->Finish();
+      mPathBuilder = nullptr;
+
+      mTransformChanged = false;
+    }
+
+    if (CurrentState().fillRule == mPath->GetFillRule()) {
+      return;
+    }
+
+    mPathBuilder = mPath->CopyToBuilder(CurrentState().fillRule);
+
+    mPath = mPathBuilder->Finish();
+    mPathBuilder = nullptr;
+    return;
+  }
+
+  EnsurePathBuilder();
+  mPath = mPathBuilder->Finish();
+  mPathBuilder = nullptr;
+}
+
+void
+gfxContext::EnsurePathBuilder()
+{
+  if (mPathBuilder && !mTransformChanged) {
+    return;
+  }
+
+  if (mPath) {
+    if (!mTransformChanged) {
+      mPathBuilder = mPath->CopyToBuilder(CurrentState().fillRule);
+      mPath = nullptr;
+    } else {
+      Matrix invTransform = mTransform;
+      invTransform.Invert();
+      Matrix toNewUS = mPathTransform * invTransform;
+      mPathBuilder = mPath->TransformedCopyToBuilder(toNewUS, CurrentState().fillRule);
+    }
+    return;
+  }
+
+  DebugOnly<PathBuilder*> oldPath = mPathBuilder.get();
+
+  if (!mPathBuilder) {
+    mPathBuilder = mDT->CreatePathBuilder(CurrentState().fillRule);
+
+    if (mPathIsRect) {
+      mPathBuilder->MoveTo(mRect.TopLeft());
+      mPathBuilder->LineTo(mRect.TopRight());
+      mPathBuilder->LineTo(mRect.BottomRight());
+      mPathBuilder->LineTo(mRect.BottomLeft());
+      mPathBuilder->Close();
+    }
+  }
+
+  if (mTransformChanged) {
+    // This could be an else if since this should never happen when
+    // mPathBuilder is nullptr and mPath is nullptr. But this way we can
+    // assert if all the state is as expected.
+    MOZ_ASSERT(oldPath);
+    MOZ_ASSERT(!mPathIsRect);
+
+    Matrix invTransform = mTransform;
+    invTransform.Invert();
+    Matrix toNewUS = mPathTransform * invTransform;
+
+    RefPtr<Path> path = mPathBuilder->Finish();
+    mPathBuilder = path->TransformedCopyToBuilder(toNewUS, CurrentState().fillRule);
+  }
+
+  mPathIsRect = false;
+}
+
+void
+gfxContext::FillAzure(Float aOpacity)
+{
+  AzureState &state = CurrentState();
+
+  CompositionOp op = GetOp();
+
+  if (mPathIsRect) {
+    MOZ_ASSERT(!mTransformChanged);
+
+    if (state.opIsClear) {
+      mDT->ClearRect(mRect);
+    } else if (op == CompositionOp::OP_SOURCE) {
+      // Emulate cairo operator source which is bound by mask!
+      mDT->ClearRect(mRect);
+      mDT->FillRect(mRect, GeneralPattern(this), DrawOptions(aOpacity));
+    } else {
+      mDT->FillRect(mRect, GeneralPattern(this), DrawOptions(aOpacity, op, state.aaMode));
+    }
+  } else {
+    EnsurePath();
+
+    NS_ASSERTION(!state.opIsClear, "We shouldn't be clearing complex paths!");
+
+    mDT->Fill(mPath, GeneralPattern(this), DrawOptions(aOpacity, op, state.aaMode));
+  }
+}
+
+void
+gfxContext::PushClipsToDT(DrawTarget *aDT)
+{
+  // Tricky, we have to restore all clips -since the last time- the clip
+  // was reset. If we didn't reset the clip, just popping the clips we
+  // added was fine.
+  unsigned int lastReset = 0;
+  for (int i = mStateStack.Length() - 2; i > 0; i--) {
+    if (mStateStack[i].clipWasReset) {
+      lastReset = i;
+      break;
+    }
+  }
+
+  // Don't need to save the old transform, we'll be setting a new one soon!
+
+  // Push all clips from the last state on the stack where the clip was
+  // reset to the clip before ours.
+  for (unsigned int i = lastReset; i < mStateStack.Length() - 1; i++) {
+    for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
+      aDT->SetTransform(mStateStack[i].pushedClips[c].transform * GetDeviceTransform());
+      if (mStateStack[i].pushedClips[c].path) {
+        aDT->PushClip(mStateStack[i].pushedClips[c].path);
+      } else {
+        aDT->PushClipRect(mStateStack[i].pushedClips[c].rect);
+      }
+    }
+  }
+}
+
+CompositionOp
+gfxContext::GetOp()
+{
+  if (CurrentState().op != CompositionOp::OP_SOURCE) {
+    return CurrentState().op;
+  }
+
+  AzureState &state = CurrentState();
+  if (state.pattern) {
+    if (state.pattern->IsOpaque()) {
+      return CompositionOp::OP_OVER;
+    } else {
+      return CompositionOp::OP_SOURCE;
+    }
+  } else if (state.sourceSurface) {
+    if (state.sourceSurface->GetFormat() == SurfaceFormat::B8G8R8X8) {
+      return CompositionOp::OP_OVER;
+    } else {
+      return CompositionOp::OP_SOURCE;
+    }
+  } else {
+    if (state.color.a > 0.999) {
+      return CompositionOp::OP_OVER;
+    } else {
+      return CompositionOp::OP_SOURCE;
+    }
+  }
+}
+
+/* SVG font code can change the transform after having set the pattern on the
+ * context. When the pattern is set it is in user space, if the transform is
+ * changed after doing so the pattern needs to be converted back into userspace.
+ * We just store the old pattern transform here so that we only do the work
+ * needed here if the pattern is actually used.
+ * We need to avoid doing this when this ChangeTransform comes from a restore,
+ * since the current pattern and the current transform are both part of the
+ * state we know the new CurrentState()'s values are valid. But if we assume
+ * a change they might become invalid since patternTransformChanged is part of
+ * the state and might be false for the restored AzureState.
+ */
+void
+gfxContext::ChangeTransform(const Matrix &aNewMatrix, bool aUpdatePatternTransform)
+{
+  AzureState &state = CurrentState();
+
+  if (aUpdatePatternTransform && (state.pattern || state.sourceSurface)
+      && !state.patternTransformChanged) {
+    state.patternTransform = GetDTTransform();
+    state.patternTransformChanged = true;
+  }
+
+  if (mPathIsRect) {
+    Matrix invMatrix = aNewMatrix;
+    
+    invMatrix.Invert();
+
+    Matrix toNewUS = mTransform * invMatrix;
+
+    if (toNewUS.IsRectilinear()) {
+      mRect = toNewUS.TransformBounds(mRect);
+      mRect.NudgeToIntegers();
+    } else {
+      mPathBuilder = mDT->CreatePathBuilder(CurrentState().fillRule);
+      
+      mPathBuilder->MoveTo(toNewUS * mRect.TopLeft());
+      mPathBuilder->LineTo(toNewUS * mRect.TopRight());
+      mPathBuilder->LineTo(toNewUS * mRect.BottomRight());
+      mPathBuilder->LineTo(toNewUS * mRect.BottomLeft());
+      mPathBuilder->Close();
+
+      mPathIsRect = false;
+    }
+
+    // No need to consider the transform changed now!
+    mTransformChanged = false;
+  } else if ((mPath || mPathBuilder) && !mTransformChanged) {
+    mTransformChanged = true;
+    mPathTransform = mTransform;
+  }
+
+  mTransform = aNewMatrix;
+
+  mDT->SetTransform(GetDTTransform());
+}
+
+Rect
+gfxContext::GetAzureDeviceSpaceClipBounds()
+{
+  unsigned int lastReset = 0;
+  for (int i = mStateStack.Length() - 1; i > 0; i--) {
+    if (mStateStack[i].clipWasReset) {
+      lastReset = i;
+      break;
+    }
+  }
+
+  Rect rect(CurrentState().deviceOffset.x, CurrentState().deviceOffset.y,
+            Float(mDT->GetSize().width), Float(mDT->GetSize().height));
+  for (unsigned int i = lastReset; i < mStateStack.Length(); i++) {
+    for (unsigned int c = 0; c < mStateStack[i].pushedClips.Length(); c++) {
+      AzureState::PushedClip &clip = mStateStack[i].pushedClips[c];
+      if (clip.path) {
+        Rect bounds = clip.path->GetBounds(clip.transform);
+        rect.IntersectRect(rect, bounds);
+      } else {
+        rect.IntersectRect(rect, clip.transform.TransformBounds(clip.rect));
+      }
+    }
+  }
+
+  return rect;
+}
+
+Point
+gfxContext::GetDeviceOffset() const
+{
+  return CurrentState().deviceOffset;
+}
+
+Matrix
+gfxContext::GetDeviceTransform() const
+{
+  Matrix mat;
+  mat.Translate(-CurrentState().deviceOffset.x, -CurrentState().deviceOffset.y);
+  return mat;
+}
+
+Matrix
+gfxContext::GetDTTransform() const
+{
+  Matrix mat = mTransform;
+  mat._31 -= CurrentState().deviceOffset.x;
+  mat._32 -= CurrentState().deviceOffset.y;
+  return mat;
+}
+
+void
+gfxContext::PushNewDT(gfxContentType content)
+{
+  Rect clipBounds = GetAzureDeviceSpaceClipBounds();
+  clipBounds.RoundOut();
+
+  clipBounds.width = std::max(1.0f, clipBounds.width);
+  clipBounds.height = std::max(1.0f, clipBounds.height);
+
+  SurfaceFormat format = gfxPlatform::GetPlatform()->Optimal2DFormatForContent(content);
+
+  RefPtr<DrawTarget> newDT =
+    mDT->CreateSimilarDrawTarget(IntSize(int32_t(clipBounds.width), int32_t(clipBounds.height)),
+                                 format);
+
+  if (!newDT) {
+    NS_WARNING("Failed to create DrawTarget of sufficient size.");
+    newDT = mDT->CreateSimilarDrawTarget(IntSize(64, 64), format);
+
+    if (!newDT) {
+      // If even this fails.. we're most likely just out of memory!
+      NS_ABORT_OOM(BytesPerPixel(format) * 64 * 64);
+    }
+  }
+
+  Save();
+
+  CurrentState().drawTarget = newDT;
+  CurrentState().deviceOffset = clipBounds.TopLeft();
+
+  mDT = newDT;
+}
+
+/**
+ * Work out whether cairo will snap inter-glyph spacing to pixels.
+ *
+ * Layout does not align text to pixel boundaries, so, with font drawing
+ * backends that snap glyph positions to pixels, it is important that
+ * inter-glyph spacing within words is always an integer number of pixels.
+ * This ensures that the drawing backend snaps all of the word's glyphs in the
+ * same direction and so inter-glyph spacing remains the same.
+ */
+void
+gfxContext::GetRoundOffsetsToPixels(bool *aRoundX, bool *aRoundY)
+{
+    *aRoundX = false;
+    // Could do something fancy here for ScaleFactors of
+    // AxisAlignedTransforms, but we leave things simple.
+    // Not much point rounding if a matrix will mess things up anyway.
+    // Also return false for non-cairo contexts.
+    if (CurrentMatrix().HasNonTranslation() || mDT) {
+        *aRoundY = false;
+        return;
+    }
+
+    // All raster backends snap glyphs to pixels vertically.
+    // Print backends set CAIRO_HINT_METRICS_OFF.
+    *aRoundY = true;
+
+    cairo_t *cr = GetCairo();
+    cairo_scaled_font_t *scaled_font = cairo_get_scaled_font(cr);
+    // Sometimes hint metrics gets set for us, most notably for printing.
+    cairo_font_options_t *font_options = cairo_font_options_create();
+    cairo_scaled_font_get_font_options(scaled_font, font_options);
+    cairo_hint_metrics_t hint_metrics =
+        cairo_font_options_get_hint_metrics(font_options);
+    cairo_font_options_destroy(font_options);
+
+    switch (hint_metrics) {
+    case CAIRO_HINT_METRICS_OFF:
+        *aRoundY = false;
+        return;
+    case CAIRO_HINT_METRICS_DEFAULT:
+        // Here we mimic what cairo surface/font backends do.  Printing
+        // surfaces have already been handled by hint_metrics.  The
+        // fallback show_glyphs implementation composites pixel-aligned
+        // glyph surfaces, so we just pick surface/font combinations that
+        // override this.
+        switch (cairo_scaled_font_get_type(scaled_font)) {
+#if CAIRO_HAS_DWRITE_FONT // dwrite backend is not in std cairo releases yet
+        case CAIRO_FONT_TYPE_DWRITE:
+            // show_glyphs is implemented on the font and so is used for
+            // all surface types; however, it may pixel-snap depending on
+            // the dwrite rendering mode
+            if (!cairo_dwrite_scaled_font_get_force_GDI_classic(scaled_font) &&
+                gfxWindowsPlatform::GetPlatform()->DWriteMeasuringMode() ==
+                    DWRITE_MEASURING_MODE_NATURAL) {
+                return;
+            }
+#endif
+        case CAIRO_FONT_TYPE_QUARTZ:
+            // Quartz surfaces implement show_glyphs for Quartz fonts
+            if (cairo_surface_get_type(cairo_get_target(cr)) ==
+                CAIRO_SURFACE_TYPE_QUARTZ) {
+                return;
+            }
+        default:
+            break;
+        }
+        // fall through:
+    case CAIRO_HINT_METRICS_ON:
+        break;
+    }
+    *aRoundX = true;
+    return;
+}