Add m-esr52 at 52.6.0

1 files changed, 967 insertions, 0 deletions

diff --git a/gfx/2d/HelpersD2D.h b/gfx/2d/HelpersD2D.h
new file mode 100644
index 000000000..48aec2cb5
--- /dev/null
+++ b/gfx/2d/HelpersD2D.h
@@ -0,0 +1,967 @@
+/* -*- 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 MOZILLA_GFX_HELPERSD2D_H_
+#define MOZILLA_GFX_HELPERSD2D_H_
+
+#include <d2d1_1.h>
+
+#include <vector>
+
+#include <dwrite.h>
+#include <versionhelpers.h>
+#include "2D.h"
+#include "Logging.h"
+#include "Tools.h"
+#include "ImageScaling.h"
+
+#include "ScaledFontDWrite.h"
+
+#undef min
+#undef max
+
+namespace mozilla {
+namespace gfx {
+
+ID2D1Factory1* D2DFactory1();
+static ID2D1Factory* D2DFactory() { return D2DFactory1(); }
+
+static inline D2D1_POINT_2F D2DPoint(const Point &aPoint)
+{
+  return D2D1::Point2F(aPoint.x, aPoint.y);
+}
+
+static inline D2D1_SIZE_U D2DIntSize(const IntSize &aSize)
+{
+  return D2D1::SizeU(aSize.width, aSize.height);
+}
+
+template <typename T>
+static inline D2D1_RECT_F D2DRect(const T &aRect)
+{
+  return D2D1::RectF(aRect.x, aRect.y, aRect.XMost(), aRect.YMost());
+}
+
+static inline D2D1_EXTEND_MODE D2DExtend(ExtendMode aExtendMode, Axis aAxis)
+{
+  D2D1_EXTEND_MODE extend;
+  switch (aExtendMode) {
+  case ExtendMode::REPEAT:
+    extend = D2D1_EXTEND_MODE_WRAP;
+    break;
+  case ExtendMode::REPEAT_X:
+  {
+    extend = aAxis == Axis::X_AXIS
+             ? D2D1_EXTEND_MODE_WRAP
+             : D2D1_EXTEND_MODE_CLAMP;
+    break;
+  }
+  case ExtendMode::REPEAT_Y:
+  {
+    extend = aAxis == Axis::Y_AXIS
+             ? D2D1_EXTEND_MODE_WRAP
+             : D2D1_EXTEND_MODE_CLAMP;
+    break;
+  }
+  case ExtendMode::REFLECT:
+    extend = D2D1_EXTEND_MODE_MIRROR;
+    break;
+  default:
+    extend = D2D1_EXTEND_MODE_CLAMP;
+  }
+
+  return extend;
+}
+
+static inline D2D1_BITMAP_INTERPOLATION_MODE D2DFilter(const SamplingFilter aSamplingFilter)
+{
+  switch (aSamplingFilter) {
+  case SamplingFilter::POINT:
+    return D2D1_BITMAP_INTERPOLATION_MODE_NEAREST_NEIGHBOR;
+  default:
+    return D2D1_BITMAP_INTERPOLATION_MODE_LINEAR;
+  }
+}
+
+static inline D2D1_INTERPOLATION_MODE D2DInterpolationMode(const SamplingFilter aSamplingFilter)
+{
+  switch (aSamplingFilter) {
+  case SamplingFilter::POINT:
+    return D2D1_INTERPOLATION_MODE_NEAREST_NEIGHBOR;
+  default:
+    return D2D1_INTERPOLATION_MODE_LINEAR;
+  }
+}
+
+static inline D2D1_MATRIX_5X4_F D2DMatrix5x4(const Matrix5x4 &aMatrix)
+{
+  return D2D1::Matrix5x4F(aMatrix._11, aMatrix._12, aMatrix._13, aMatrix._14,
+                          aMatrix._21, aMatrix._22, aMatrix._23, aMatrix._24,
+                          aMatrix._31, aMatrix._32, aMatrix._33, aMatrix._34,
+                          aMatrix._41, aMatrix._42, aMatrix._43, aMatrix._44,
+                          aMatrix._51, aMatrix._52, aMatrix._53, aMatrix._54);
+}
+
+static inline D2D1_VECTOR_3F D2DVector3D(const Point3D &aPoint)
+{
+  return D2D1::Vector3F(aPoint.x, aPoint.y, aPoint.z);
+}
+
+static inline D2D1_ANTIALIAS_MODE D2DAAMode(AntialiasMode aMode)
+{
+  switch (aMode) {
+  case AntialiasMode::NONE:
+    return D2D1_ANTIALIAS_MODE_ALIASED;
+  default:
+    return D2D1_ANTIALIAS_MODE_PER_PRIMITIVE;
+  }
+}
+
+static inline D2D1_MATRIX_3X2_F D2DMatrix(const Matrix &aTransform)
+{
+  return D2D1::Matrix3x2F(aTransform._11, aTransform._12,
+                          aTransform._21, aTransform._22,
+                          aTransform._31, aTransform._32);
+}
+
+static inline D2D1_COLOR_F D2DColor(const Color &aColor)
+{
+  return D2D1::ColorF(aColor.r, aColor.g, aColor.b, aColor.a);
+}
+
+static inline IntSize ToIntSize(const D2D1_SIZE_U &aSize)
+{
+  return IntSize(aSize.width, aSize.height);
+}
+
+static inline SurfaceFormat ToPixelFormat(const D2D1_PIXEL_FORMAT &aFormat)
+{
+  switch(aFormat.format) {
+  case DXGI_FORMAT_A8_UNORM:
+  case DXGI_FORMAT_R8_UNORM:
+    return SurfaceFormat::A8;
+  case DXGI_FORMAT_B8G8R8A8_UNORM:
+    if (aFormat.alphaMode == D2D1_ALPHA_MODE_IGNORE) {
+      return SurfaceFormat::B8G8R8X8;
+    } else {
+      return SurfaceFormat::B8G8R8A8;
+    }
+  default:
+    return SurfaceFormat::B8G8R8A8;
+  }
+}
+
+static inline Rect ToRect(const D2D1_RECT_F &aRect)
+{
+  return Rect(aRect.left, aRect.top, aRect.right - aRect.left, aRect.bottom - aRect.top);
+}
+
+static inline Matrix ToMatrix(const D2D1_MATRIX_3X2_F &aTransform)
+{
+  return Matrix(aTransform._11, aTransform._12,
+                aTransform._21, aTransform._22,
+                aTransform._31, aTransform._32);
+}
+
+static inline Point ToPoint(const D2D1_POINT_2F &aPoint)
+{
+  return Point(aPoint.x, aPoint.y);
+}
+
+static inline DXGI_FORMAT DXGIFormat(SurfaceFormat aFormat)
+{
+  switch (aFormat) {
+  case SurfaceFormat::B8G8R8A8:
+    return DXGI_FORMAT_B8G8R8A8_UNORM;
+  case SurfaceFormat::B8G8R8X8:
+    return DXGI_FORMAT_B8G8R8A8_UNORM;
+  case SurfaceFormat::A8:
+    return DXGI_FORMAT_A8_UNORM;
+  default:
+    return DXGI_FORMAT_UNKNOWN;
+  }
+}
+
+static inline D2D1_ALPHA_MODE D2DAlphaModeForFormat(SurfaceFormat aFormat)
+{
+  switch (aFormat) {
+  case SurfaceFormat::B8G8R8X8:
+    return D2D1_ALPHA_MODE_IGNORE;
+  default:
+    return D2D1_ALPHA_MODE_PREMULTIPLIED;
+  }
+}
+
+static inline D2D1_PIXEL_FORMAT D2DPixelFormat(SurfaceFormat aFormat)
+{
+  return D2D1::PixelFormat(DXGIFormat(aFormat), D2DAlphaModeForFormat(aFormat));
+}
+
+static inline bool D2DSupportsCompositeMode(CompositionOp aOp)
+{
+  switch(aOp) {
+  case CompositionOp::OP_OVER:
+  case CompositionOp::OP_ADD:
+  case CompositionOp::OP_ATOP:
+  case CompositionOp::OP_OUT:
+  case CompositionOp::OP_IN:
+  case CompositionOp::OP_SOURCE:
+  case CompositionOp::OP_DEST_IN:
+  case CompositionOp::OP_DEST_OUT:
+  case CompositionOp::OP_DEST_OVER:
+  case CompositionOp::OP_DEST_ATOP:
+  case CompositionOp::OP_XOR:
+    return true;
+  default:
+    return false;
+  }
+}
+
+static inline D2D1_COMPOSITE_MODE D2DCompositionMode(CompositionOp aOp)
+{
+  switch(aOp) {
+  case CompositionOp::OP_OVER:
+    return D2D1_COMPOSITE_MODE_SOURCE_OVER;
+  case CompositionOp::OP_ADD:
+    return D2D1_COMPOSITE_MODE_PLUS;
+  case CompositionOp::OP_ATOP:
+    return D2D1_COMPOSITE_MODE_SOURCE_ATOP;
+  case CompositionOp::OP_OUT:
+    return D2D1_COMPOSITE_MODE_SOURCE_OUT;
+  case CompositionOp::OP_IN:
+    return D2D1_COMPOSITE_MODE_SOURCE_IN;
+  case CompositionOp::OP_SOURCE:
+    return D2D1_COMPOSITE_MODE_SOURCE_COPY;
+  case CompositionOp::OP_DEST_IN:
+    return D2D1_COMPOSITE_MODE_DESTINATION_IN;
+  case CompositionOp::OP_DEST_OUT:
+    return D2D1_COMPOSITE_MODE_DESTINATION_OUT;
+  case CompositionOp::OP_DEST_OVER:
+    return D2D1_COMPOSITE_MODE_DESTINATION_OVER;
+  case CompositionOp::OP_DEST_ATOP:
+    return D2D1_COMPOSITE_MODE_DESTINATION_ATOP;
+  case CompositionOp::OP_XOR:
+    return D2D1_COMPOSITE_MODE_XOR;
+  default:
+    return D2D1_COMPOSITE_MODE_SOURCE_OVER;
+  }
+}
+
+static inline D2D1_BLEND_MODE D2DBlendMode(CompositionOp aOp)
+{
+  switch (aOp) {
+  case CompositionOp::OP_MULTIPLY:
+    return D2D1_BLEND_MODE_MULTIPLY;
+  case CompositionOp::OP_SCREEN:
+    return D2D1_BLEND_MODE_SCREEN;
+  case CompositionOp::OP_OVERLAY:
+    return D2D1_BLEND_MODE_OVERLAY;
+  case CompositionOp::OP_DARKEN:
+    return D2D1_BLEND_MODE_DARKEN;
+  case CompositionOp::OP_LIGHTEN:
+    return D2D1_BLEND_MODE_LIGHTEN;
+  case CompositionOp::OP_COLOR_DODGE:
+    return D2D1_BLEND_MODE_COLOR_DODGE;
+  case CompositionOp::OP_COLOR_BURN:
+    return D2D1_BLEND_MODE_COLOR_BURN;
+  case CompositionOp::OP_HARD_LIGHT:
+    return D2D1_BLEND_MODE_HARD_LIGHT;
+  case CompositionOp::OP_SOFT_LIGHT:
+    return D2D1_BLEND_MODE_SOFT_LIGHT;
+  case CompositionOp::OP_DIFFERENCE:
+    return D2D1_BLEND_MODE_DIFFERENCE;
+  case CompositionOp::OP_EXCLUSION:
+    return D2D1_BLEND_MODE_EXCLUSION;
+  case CompositionOp::OP_HUE:
+    return D2D1_BLEND_MODE_HUE;
+  case CompositionOp::OP_SATURATION:
+    return D2D1_BLEND_MODE_SATURATION;
+  case CompositionOp::OP_COLOR:
+    return D2D1_BLEND_MODE_COLOR;
+  case CompositionOp::OP_LUMINOSITY:
+    return D2D1_BLEND_MODE_LUMINOSITY;
+  default:
+    return D2D1_BLEND_MODE_MULTIPLY;
+  }
+}
+
+static inline bool D2DSupportsPrimitiveBlendMode(CompositionOp aOp)
+{
+  switch (aOp) {
+    case CompositionOp::OP_OVER:
+//  case CompositionOp::OP_SOURCE:
+      return true;
+//  case CompositionOp::OP_DARKEN:
+    case CompositionOp::OP_ADD:
+      return IsWindows8Point1OrGreater();
+    default:
+      return false;
+  }
+}
+
+static inline D2D1_PRIMITIVE_BLEND D2DPrimitiveBlendMode(CompositionOp aOp)
+{
+  switch (aOp) {
+    case CompositionOp::OP_OVER:
+      return D2D1_PRIMITIVE_BLEND_SOURCE_OVER;
+    // D2D1_PRIMITIVE_BLEND_COPY should leave pixels out of the source's
+    // bounds unchanged, but doesn't- breaking unbounded ops.
+    // D2D1_PRIMITIVE_BLEND_MIN doesn't quite work like darken either, as it
+    // accounts for the source alpha.
+    //
+    // case CompositionOp::OP_SOURCE:
+    //   return D2D1_PRIMITIVE_BLEND_COPY;
+    // case CompositionOp::OP_DARKEN:
+    //   return D2D1_PRIMITIVE_BLEND_MIN;
+    case CompositionOp::OP_ADD:
+      return D2D1_PRIMITIVE_BLEND_ADD;
+    default:
+      return D2D1_PRIMITIVE_BLEND_SOURCE_OVER;
+  }
+}
+
+static inline bool IsPatternSupportedByD2D(const Pattern &aPattern)
+{
+  if (aPattern.GetType() != PatternType::RADIAL_GRADIENT) {
+    return true;
+  }
+
+  const RadialGradientPattern *pat =
+    static_cast<const RadialGradientPattern*>(&aPattern);
+  
+  if (pat->mRadius1 != 0) {
+    return false;
+  }
+
+  Point diff = pat->mCenter2 - pat->mCenter1;
+
+  if (sqrt(diff.x * diff.x + diff.y * diff.y) >= pat->mRadius2) {
+    // Inner point lies outside the circle.
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * This structure is used to pass rectangles to our shader constant. We can use
+ * this for passing rectangular areas to SetVertexShaderConstant. In the format
+ * of a 4 component float(x,y,width,height). Our vertex shader can then use
+ * this to construct rectangular positions from the 0,0-1,1 quad that we source
+ * it with.
+ */
+struct ShaderConstantRectD3D10
+{
+  float mX, mY, mWidth, mHeight;
+  ShaderConstantRectD3D10(float aX, float aY, float aWidth, float aHeight)
+    : mX(aX), mY(aY), mWidth(aWidth), mHeight(aHeight)
+  { }
+
+  // For easy passing to SetVertexShaderConstantF.
+  operator float* () { return &mX; }
+};
+
+static inline DWRITE_MATRIX
+DWriteMatrixFromMatrix(Matrix &aMatrix)
+{
+  DWRITE_MATRIX mat;
+  mat.m11 = aMatrix._11;
+  mat.m12 = aMatrix._12;
+  mat.m21 = aMatrix._21;
+  mat.m22 = aMatrix._22;
+  mat.dx = aMatrix._31;
+  mat.dy = aMatrix._32;
+  return mat;
+}
+
+class AutoDWriteGlyphRun : public DWRITE_GLYPH_RUN
+{
+    static const unsigned kNumAutoGlyphs = 256;
+
+public:
+    AutoDWriteGlyphRun() {
+        glyphCount = 0;
+    }
+
+    ~AutoDWriteGlyphRun() {
+        if (glyphCount > kNumAutoGlyphs) {
+            delete[] glyphIndices;
+            delete[] glyphAdvances;
+            delete[] glyphOffsets;
+        }
+    }
+
+    void allocate(unsigned aNumGlyphs) {
+        glyphCount = aNumGlyphs;
+        if (aNumGlyphs <= kNumAutoGlyphs) {
+            glyphIndices = &mAutoIndices[0];
+            glyphAdvances = &mAutoAdvances[0];
+            glyphOffsets = &mAutoOffsets[0];
+        } else {
+            glyphIndices = new UINT16[aNumGlyphs];
+            glyphAdvances = new FLOAT[aNumGlyphs];
+            glyphOffsets = new DWRITE_GLYPH_OFFSET[aNumGlyphs];
+        }
+    }
+
+private:
+    DWRITE_GLYPH_OFFSET mAutoOffsets[kNumAutoGlyphs];
+    FLOAT               mAutoAdvances[kNumAutoGlyphs];
+    UINT16              mAutoIndices[kNumAutoGlyphs];
+};
+
+static inline void
+DWriteGlyphRunFromGlyphs(const GlyphBuffer &aGlyphs, ScaledFontDWrite *aFont, AutoDWriteGlyphRun *run)
+{
+  run->allocate(aGlyphs.mNumGlyphs);
+
+  FLOAT *advances = const_cast<FLOAT*>(run->glyphAdvances);
+  UINT16 *indices = const_cast<UINT16*>(run->glyphIndices);
+  DWRITE_GLYPH_OFFSET *offsets = const_cast<DWRITE_GLYPH_OFFSET*>(run->glyphOffsets);
+
+  memset(advances, 0, sizeof(FLOAT) * aGlyphs.mNumGlyphs);
+  for (unsigned int i = 0; i < aGlyphs.mNumGlyphs; i++) {
+    indices[i] = aGlyphs.mGlyphs[i].mIndex;
+    offsets[i].advanceOffset = aGlyphs.mGlyphs[i].mPosition.x;
+    offsets[i].ascenderOffset = -aGlyphs.mGlyphs[i].mPosition.y;
+  }
+    
+  run->bidiLevel = 0;
+  run->fontFace = aFont->mFontFace;
+  run->fontEmSize = aFont->GetSize();
+  run->glyphCount = aGlyphs.mNumGlyphs;
+  run->isSideways = FALSE;
+}
+
+static inline already_AddRefed<ID2D1Geometry>
+ConvertRectToGeometry(const D2D1_RECT_F& aRect)
+{
+  RefPtr<ID2D1RectangleGeometry> rectGeom;
+  D2DFactory()->CreateRectangleGeometry(&aRect, getter_AddRefs(rectGeom));
+  return rectGeom.forget();
+}
+
+static inline already_AddRefed<ID2D1Geometry>
+GetTransformedGeometry(ID2D1Geometry *aGeometry, const D2D1_MATRIX_3X2_F &aTransform)
+{
+  RefPtr<ID2D1PathGeometry> tmpGeometry;
+  D2DFactory()->CreatePathGeometry(getter_AddRefs(tmpGeometry));
+  RefPtr<ID2D1GeometrySink> currentSink;
+  tmpGeometry->Open(getter_AddRefs(currentSink));
+  aGeometry->Simplify(D2D1_GEOMETRY_SIMPLIFICATION_OPTION_CUBICS_AND_LINES,
+                      aTransform, currentSink);
+  currentSink->Close();
+  return tmpGeometry.forget();
+}
+
+static inline already_AddRefed<ID2D1Geometry>
+IntersectGeometry(ID2D1Geometry *aGeometryA, ID2D1Geometry *aGeometryB)
+{
+  RefPtr<ID2D1PathGeometry> pathGeom;
+  D2DFactory()->CreatePathGeometry(getter_AddRefs(pathGeom));
+  RefPtr<ID2D1GeometrySink> sink;
+  pathGeom->Open(getter_AddRefs(sink));
+  aGeometryA->CombineWithGeometry(aGeometryB, D2D1_COMBINE_MODE_INTERSECT, nullptr, sink);
+  sink->Close();
+
+  return pathGeom.forget();
+}
+
+static inline already_AddRefed<ID2D1StrokeStyle>
+CreateStrokeStyleForOptions(const StrokeOptions &aStrokeOptions)
+{
+  RefPtr<ID2D1StrokeStyle> style;
+
+  D2D1_CAP_STYLE capStyle;
+  D2D1_LINE_JOIN joinStyle;
+
+  switch (aStrokeOptions.mLineCap) {
+  case CapStyle::BUTT:
+    capStyle = D2D1_CAP_STYLE_FLAT;
+    break;
+  case CapStyle::ROUND:
+    capStyle = D2D1_CAP_STYLE_ROUND;
+    break;
+  case CapStyle::SQUARE:
+    capStyle = D2D1_CAP_STYLE_SQUARE;
+    break;
+  }
+
+  switch (aStrokeOptions.mLineJoin) {
+  case JoinStyle::MITER:
+    joinStyle = D2D1_LINE_JOIN_MITER;
+    break;
+  case JoinStyle::MITER_OR_BEVEL:
+    joinStyle = D2D1_LINE_JOIN_MITER_OR_BEVEL;
+    break;
+  case JoinStyle::ROUND:
+    joinStyle = D2D1_LINE_JOIN_ROUND;
+    break;
+  case JoinStyle::BEVEL:
+    joinStyle = D2D1_LINE_JOIN_BEVEL;
+    break;
+  }
+
+
+  HRESULT hr;
+  // We need to check mDashLength in addition to mDashPattern here since if
+  // mDashPattern is set but mDashLength is zero then the stroke will fail to
+  // paint.
+  if (aStrokeOptions.mDashLength > 0 && aStrokeOptions.mDashPattern) {
+    typedef std::vector<Float> FloatVector;
+    // D2D "helpfully" multiplies the dash pattern by the line width.
+    // That's not what cairo does, or is what <canvas>'s dash wants.
+    // So fix the multiplication in advance.
+    Float lineWidth = aStrokeOptions.mLineWidth;
+    FloatVector dash(aStrokeOptions.mDashPattern,
+                     aStrokeOptions.mDashPattern + aStrokeOptions.mDashLength);
+    for (FloatVector::iterator it = dash.begin(); it != dash.end(); ++it) {
+      *it /= lineWidth;
+    }
+
+    hr = D2DFactory()->CreateStrokeStyle(
+      D2D1::StrokeStyleProperties(capStyle, capStyle,
+                                  capStyle, joinStyle,
+                                  aStrokeOptions.mMiterLimit,
+                                  D2D1_DASH_STYLE_CUSTOM,
+                                  aStrokeOptions.mDashOffset / lineWidth),
+      &dash[0], // data() is not C++98, although it's in recent gcc
+                // and VC10's STL
+      dash.size(),
+      getter_AddRefs(style));
+  } else {
+    hr = D2DFactory()->CreateStrokeStyle(
+      D2D1::StrokeStyleProperties(capStyle, capStyle,
+                                  capStyle, joinStyle,
+                                  aStrokeOptions.mMiterLimit),
+      nullptr, 0, getter_AddRefs(style));
+  }
+
+  if (FAILED(hr)) {
+    gfxWarning() << "Failed to create Direct2D stroke style.";
+  }
+
+  return style.forget();
+}
+
+// This creates a (partially) uploaded bitmap for a DataSourceSurface. It
+// uploads the minimum requirement and possibly downscales. It adjusts the
+// input Matrix to compensate.
+static inline already_AddRefed<ID2D1Bitmap>
+CreatePartialBitmapForSurface(DataSourceSurface *aSurface, const Matrix &aDestinationTransform,
+                              const IntSize &aDestinationSize, ExtendMode aExtendMode,
+                              Matrix &aSourceTransform, ID2D1RenderTarget *aRT,
+                              const IntRect* aSourceRect = nullptr)
+{
+  RefPtr<ID2D1Bitmap> bitmap;
+
+  // This is where things get complicated. The source surface was
+  // created for a surface that was too large to fit in a texture.
+  // We'll need to figure out if we can work with a partial upload
+  // or downsample in software.
+
+  Matrix transform = aDestinationTransform;
+  Matrix invTransform = transform = aSourceTransform * transform;
+  if (!invTransform.Invert()) {
+    // Singular transform, nothing to be drawn.
+    return nullptr;
+  }
+
+  Rect rect(0, 0, Float(aDestinationSize.width), Float(aDestinationSize.height));
+
+  // Calculate the rectangle of the source mapped to our surface.
+  rect = invTransform.TransformBounds(rect);
+  rect.RoundOut();
+
+  IntSize size = aSurface->GetSize();
+
+  Rect uploadRect(0, 0, Float(size.width), Float(size.height));
+  if (aSourceRect) {
+    uploadRect = Rect(aSourceRect->x, aSourceRect->y, aSourceRect->width, aSourceRect->height);
+  }
+
+  // Limit the uploadRect as much as possible without supporting discontiguous uploads 
+  //
+  //                               region we will paint from
+  //   uploadRect
+  //   .---------------.              .---------------.         resulting uploadRect
+  //   |               |rect          |               |
+  //   |          .---------.         .----.     .----.          .---------------.
+  //   |          |         |  ---->  |    |     |    |   ---->  |               |
+  //   |          '---------'         '----'     '----'          '---------------'
+  //   '---------------'              '---------------'
+  //
+  //
+
+  if (uploadRect.Contains(rect)) {
+    // Extend mode is irrelevant, the displayed rect is completely contained
+    // by the source bitmap.
+    uploadRect = rect;
+  } else if (aExtendMode == ExtendMode::CLAMP && uploadRect.Intersects(rect)) {
+    // Calculate the rectangle on the source bitmap that touches our
+    // surface, and upload that, for ExtendMode::CLAMP we can actually guarantee
+    // correct behaviour in this case.
+    uploadRect = uploadRect.Intersect(rect);
+
+    // We now proceed to check if we can limit at least one dimension of the
+    // upload rect safely without looking at extend mode.
+  } else if (rect.x >= 0 && rect.XMost() < size.width) {
+    uploadRect.x = rect.x;
+    uploadRect.width = rect.width;
+  } else if (rect.y >= 0 && rect.YMost() < size.height) {
+    uploadRect.y = rect.y;
+    uploadRect.height = rect.height;
+  }
+
+  if (uploadRect.IsEmpty()) {
+    // Nothing to be drawn.
+    return nullptr;
+  }
+
+  if (uploadRect.width <= aRT->GetMaximumBitmapSize() &&
+      uploadRect.height <= aRT->GetMaximumBitmapSize()) {
+    {
+      // Scope to auto-Unmap() |mapping|.
+      DataSourceSurface::ScopedMap mapping(aSurface, DataSourceSurface::READ);
+      if (MOZ2D_WARN_IF(!mapping.IsMapped())) {
+        return nullptr;
+      }
+
+      // A partial upload will suffice.
+      aRT->CreateBitmap(D2D1::SizeU(uint32_t(uploadRect.width), uint32_t(uploadRect.height)),
+                        mapping.GetData() + int(uploadRect.x) * 4 + int(uploadRect.y) * mapping.GetStride(),
+                        mapping.GetStride(),
+                        D2D1::BitmapProperties(D2DPixelFormat(aSurface->GetFormat())),
+                        getter_AddRefs(bitmap));
+    }
+
+    aSourceTransform.PreTranslate(uploadRect.x, uploadRect.y);
+
+    return bitmap.forget();
+  } else {
+    int Bpp = BytesPerPixel(aSurface->GetFormat());
+
+    if (Bpp != 4) {
+      // This shouldn't actually happen in practice!
+      MOZ_ASSERT(false);
+      return nullptr;
+    }
+
+    {
+      // Scope to auto-Unmap() |mapping|.
+      DataSourceSurface::ScopedMap mapping(aSurface, DataSourceSurface::READ);
+      if (MOZ2D_WARN_IF(!mapping.IsMapped())) {
+        return nullptr;
+      }
+      ImageHalfScaler scaler(mapping.GetData(), mapping.GetStride(), size);
+
+      // Calculate the maximum width/height of the image post transform.
+      Point topRight = transform.TransformPoint(Point(Float(size.width), 0));
+      Point topLeft = transform.TransformPoint(Point(0, 0));
+      Point bottomRight = transform.TransformPoint(Point(Float(size.width), Float(size.height)));
+      Point bottomLeft = transform.TransformPoint(Point(0, Float(size.height)));
+
+      IntSize scaleSize;
+
+      scaleSize.width = int32_t(std::max(Distance(topRight, topLeft),
+                                         Distance(bottomRight, bottomLeft)));
+      scaleSize.height = int32_t(std::max(Distance(topRight, bottomRight),
+                                          Distance(topLeft, bottomLeft)));
+
+      if (unsigned(scaleSize.width) > aRT->GetMaximumBitmapSize()) {
+        // Ok, in this case we'd really want a downscale of a part of the bitmap,
+        // perhaps we can do this later but for simplicity let's do something
+        // different here and assume it's good enough, this should be rare!
+        scaleSize.width = 4095;
+      }
+      if (unsigned(scaleSize.height) > aRT->GetMaximumBitmapSize()) {
+        scaleSize.height = 4095;
+      }
+
+      scaler.ScaleForSize(scaleSize);
+
+      IntSize newSize = scaler.GetSize();
+
+      if (newSize.IsEmpty()) {
+        return nullptr;
+      }
+
+      aRT->CreateBitmap(D2D1::SizeU(newSize.width, newSize.height),
+                        scaler.GetScaledData(), scaler.GetStride(),
+                        D2D1::BitmapProperties(D2DPixelFormat(aSurface->GetFormat())),
+                        getter_AddRefs(bitmap));
+
+      aSourceTransform.PreScale(Float(size.width) / newSize.width,
+                                Float(size.height) / newSize.height);
+    }
+    return bitmap.forget();
+  }
+}
+
+static inline void AddRectToSink(ID2D1GeometrySink* aSink, const D2D1_RECT_F& aRect)
+{
+  aSink->BeginFigure(D2D1::Point2F(aRect.left, aRect.top), D2D1_FIGURE_BEGIN_FILLED);
+  aSink->AddLine(D2D1::Point2F(aRect.right, aRect.top));
+  aSink->AddLine(D2D1::Point2F(aRect.right, aRect.bottom));
+  aSink->AddLine(D2D1::Point2F(aRect.left, aRect.bottom));
+  aSink->EndFigure(D2D1_FIGURE_END_CLOSED);
+}
+
+class DCCommandSink : public ID2D1CommandSink
+{
+public:
+  DCCommandSink(ID2D1DeviceContext* aCtx) : mCtx(aCtx)
+  {
+  }
+
+  HRESULT STDMETHODCALLTYPE QueryInterface(const IID &aIID, void **aPtr)
+  {
+    if (!aPtr) {
+      return E_POINTER;
+    }
+
+    if (aIID == IID_IUnknown) {
+      *aPtr = static_cast<IUnknown*>(this);
+      return S_OK;
+    } else if (aIID == IID_ID2D1CommandSink) {
+      *aPtr = static_cast<ID2D1CommandSink*>(this);
+      return S_OK;
+    }
+
+    return E_NOINTERFACE;
+  }
+
+  ULONG STDMETHODCALLTYPE AddRef()
+  {
+    return 1;
+  }
+
+  ULONG STDMETHODCALLTYPE Release()
+  {
+    return 1;
+  }
+
+  STDMETHODIMP BeginDraw()
+  {
+    // We don't want to do anything here!
+    return S_OK;
+  }
+  STDMETHODIMP EndDraw()
+  {
+    // We don't want to do anything here!
+    return S_OK;
+  }
+
+  STDMETHODIMP SetAntialiasMode(
+    D2D1_ANTIALIAS_MODE antialiasMode
+    )
+  {
+    mCtx->SetAntialiasMode(antialiasMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP SetTags(D2D1_TAG tag1, D2D1_TAG tag2)
+  {
+    mCtx->SetTags(tag1, tag2);
+    return S_OK;
+  }
+
+  STDMETHODIMP SetTextAntialiasMode(D2D1_TEXT_ANTIALIAS_MODE textAntialiasMode)
+  {
+    mCtx->SetTextAntialiasMode(textAntialiasMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP SetTextRenderingParams(_In_opt_ IDWriteRenderingParams *textRenderingParams)
+  {
+    mCtx->SetTextRenderingParams(textRenderingParams);
+    return S_OK;
+  }
+
+  STDMETHODIMP  SetTransform(_In_ CONST D2D1_MATRIX_3X2_F *transform)
+  {
+    mCtx->SetTransform(transform);
+    return S_OK;
+  }
+
+  STDMETHODIMP SetPrimitiveBlend(D2D1_PRIMITIVE_BLEND primitiveBlend)
+  {
+    mCtx->SetPrimitiveBlend(primitiveBlend);
+    return S_OK;
+  }
+
+  STDMETHODIMP SetUnitMode(D2D1_UNIT_MODE unitMode)
+  {
+    mCtx->SetUnitMode(unitMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP Clear(_In_opt_ CONST D2D1_COLOR_F *color)
+  {
+    mCtx->Clear(color);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawGlyphRun(
+      D2D1_POINT_2F baselineOrigin,
+      _In_ CONST DWRITE_GLYPH_RUN *glyphRun,
+      _In_opt_ CONST DWRITE_GLYPH_RUN_DESCRIPTION *glyphRunDescription,
+      _In_ ID2D1Brush *foregroundBrush,
+      DWRITE_MEASURING_MODE measuringMode
+    )
+  {
+    mCtx->DrawGlyphRun(baselineOrigin, glyphRun, glyphRunDescription,
+                       foregroundBrush, measuringMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawLine(
+      D2D1_POINT_2F point0,
+      D2D1_POINT_2F point1,
+      _In_ ID2D1Brush *brush,
+      FLOAT strokeWidth,
+      _In_opt_ ID2D1StrokeStyle *strokeStyle
+    )
+  {
+    mCtx->DrawLine(point0, point1, brush, strokeWidth, strokeStyle);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawGeometry(
+      _In_ ID2D1Geometry *geometry,
+      _In_ ID2D1Brush *brush,
+      FLOAT strokeWidth,
+      _In_opt_ ID2D1StrokeStyle *strokeStyle
+    )
+  {
+    mCtx->DrawGeometry(geometry, brush, strokeWidth, strokeStyle);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawRectangle(
+      _In_ CONST D2D1_RECT_F *rect,
+      _In_ ID2D1Brush *brush,
+      FLOAT strokeWidth,
+      _In_opt_ ID2D1StrokeStyle *strokeStyle
+    )
+  {
+    mCtx->DrawRectangle(rect, brush, strokeWidth, strokeStyle);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawBitmap(
+      _In_ ID2D1Bitmap *bitmap,
+      _In_opt_ CONST D2D1_RECT_F *destinationRectangle,
+      FLOAT opacity,
+      D2D1_INTERPOLATION_MODE interpolationMode,
+      _In_opt_ CONST D2D1_RECT_F *sourceRectangle,
+      _In_opt_ CONST D2D1_MATRIX_4X4_F *perspectiveTransform
+    )
+  {
+    mCtx->DrawBitmap(bitmap, destinationRectangle, opacity,
+                     interpolationMode, sourceRectangle,
+                     perspectiveTransform);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawImage(
+      _In_ ID2D1Image *image,
+      _In_opt_ CONST D2D1_POINT_2F *targetOffset,
+      _In_opt_ CONST D2D1_RECT_F *imageRectangle,
+      D2D1_INTERPOLATION_MODE interpolationMode,
+      D2D1_COMPOSITE_MODE compositeMode
+    )
+  {
+    mCtx->DrawImage(image, targetOffset, imageRectangle,
+                    interpolationMode, compositeMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP DrawGdiMetafile(
+      _In_ ID2D1GdiMetafile *gdiMetafile,
+      _In_opt_ CONST D2D1_POINT_2F *targetOffset
+    )
+  {
+    mCtx->DrawGdiMetafile(gdiMetafile, targetOffset);
+    return S_OK;
+  }
+
+  STDMETHODIMP FillMesh(
+      _In_ ID2D1Mesh *mesh,
+      _In_ ID2D1Brush *brush
+    )
+  {
+    mCtx->FillMesh(mesh, brush);
+    return S_OK;
+  }
+
+  STDMETHODIMP FillOpacityMask(
+      _In_ ID2D1Bitmap *opacityMask,
+      _In_ ID2D1Brush *brush,
+      _In_opt_ CONST D2D1_RECT_F *destinationRectangle,
+      _In_opt_ CONST D2D1_RECT_F *sourceRectangle
+    )
+  {
+    mCtx->FillOpacityMask(opacityMask, brush, destinationRectangle,
+                          sourceRectangle);
+    return S_OK;
+  }
+
+  STDMETHODIMP FillGeometry(
+      _In_ ID2D1Geometry *geometry,
+      _In_ ID2D1Brush *brush,
+      _In_opt_ ID2D1Brush *opacityBrush
+    )
+  {
+    mCtx->FillGeometry(geometry, brush, opacityBrush);
+    return S_OK;
+  }
+
+  STDMETHODIMP FillRectangle(
+      _In_ CONST D2D1_RECT_F *rect,
+      _In_ ID2D1Brush *brush
+    )
+  {
+    mCtx->FillRectangle(rect, brush);
+    return S_OK;
+  }
+
+  STDMETHODIMP PushAxisAlignedClip(
+      _In_ CONST D2D1_RECT_F *clipRect,
+      D2D1_ANTIALIAS_MODE antialiasMode
+    )
+  {
+    mCtx->PushAxisAlignedClip(clipRect, antialiasMode);
+    return S_OK;
+  }
+
+  STDMETHODIMP PushLayer(
+      _In_ CONST D2D1_LAYER_PARAMETERS1 *layerParameters1,
+      _In_opt_ ID2D1Layer *layer
+    )
+  {
+    mCtx->PushLayer(layerParameters1, layer);
+    return S_OK;
+  }
+
+  STDMETHODIMP PopAxisAlignedClip()
+  {
+    mCtx->PopAxisAlignedClip();
+    return S_OK;
+  }
+
+  STDMETHODIMP PopLayer()
+  {
+    mCtx->PopLayer();
+    return S_OK;
+  }
+
+  ID2D1DeviceContext* mCtx;
+};
+
+}
+}
+
+#endif /* MOZILLA_GFX_HELPERSD2D_H_ */