Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 936 insertions, 0 deletions

diff --git a/layout/base/Units.h b/layout/base/Units.h
new file mode 100644
index 0000000000..61d0d5761c
--- /dev/null
+++ b/layout/base/Units.h
@@ -0,0 +1,936 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZ_UNITS_H_
+#define MOZ_UNITS_H_
+
+#include <type_traits>
+
+#include "mozilla/gfx/Coord.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/gfx/RectAbsolute.h"
+#include "mozilla/gfx/ScaleFactor.h"
+#include "mozilla/gfx/ScaleFactors2D.h"
+#include "nsMargin.h"
+#include "nsRect.h"
+#include "nsRegion.h"
+#include "mozilla/AppUnits.h"
+
+namespace mozilla {
+
+template <typename T>
+struct IsPixel : std::false_type {};
+
+// See struct declaration for a description of each unit type.
+struct CSSPixel;
+struct LayoutDevicePixel;
+struct LayerPixel;
+struct CSSTransformedLayerPixel;
+struct RenderTargetPixel;
+struct ScreenPixel;
+struct ParentLayerPixel;
+struct DesktopPixel;
+struct ImagePixel;
+struct ExternalPixel;
+
+template <>
+struct IsPixel<CSSPixel> : std::true_type {};
+template <>
+struct IsPixel<LayoutDevicePixel> : std::true_type {};
+template <>
+struct IsPixel<LayerPixel> : std::true_type {};
+template <>
+struct IsPixel<CSSTransformedLayerPixel> : std::true_type {};
+template <>
+struct IsPixel<RenderTargetPixel> : std::true_type {};
+template <>
+struct IsPixel<ImagePixel> : std::true_type {};
+template <>
+struct IsPixel<ScreenPixel> : std::true_type {};
+template <>
+struct IsPixel<ParentLayerPixel> : std::true_type {};
+template <>
+struct IsPixel<DesktopPixel> : std::true_type {};
+template <>
+struct IsPixel<ExternalPixel> : std::true_type {};
+
+typedef gfx::CoordTyped<CSSPixel> CSSCoord;
+typedef gfx::IntCoordTyped<CSSPixel> CSSIntCoord;
+typedef gfx::PointTyped<CSSPixel> CSSPoint;
+typedef gfx::IntPointTyped<CSSPixel> CSSIntPoint;
+typedef gfx::SizeTyped<CSSPixel> CSSSize;
+typedef gfx::IntSizeTyped<CSSPixel> CSSIntSize;
+typedef gfx::RectTyped<CSSPixel> CSSRect;
+typedef gfx::IntRectTyped<CSSPixel> CSSIntRect;
+typedef gfx::MarginTyped<CSSPixel> CSSMargin;
+typedef gfx::IntMarginTyped<CSSPixel> CSSIntMargin;
+typedef gfx::IntRegionTyped<CSSPixel> CSSIntRegion;
+
+typedef gfx::CoordTyped<LayoutDevicePixel> LayoutDeviceCoord;
+typedef gfx::IntCoordTyped<LayoutDevicePixel> LayoutDeviceIntCoord;
+typedef gfx::PointTyped<LayoutDevicePixel> LayoutDevicePoint;
+typedef gfx::IntPointTyped<LayoutDevicePixel> LayoutDeviceIntPoint;
+typedef gfx::SizeTyped<LayoutDevicePixel> LayoutDeviceSize;
+typedef gfx::IntSizeTyped<LayoutDevicePixel> LayoutDeviceIntSize;
+typedef gfx::RectTyped<LayoutDevicePixel> LayoutDeviceRect;
+typedef gfx::IntRectTyped<LayoutDevicePixel> LayoutDeviceIntRect;
+typedef gfx::MarginTyped<LayoutDevicePixel> LayoutDeviceMargin;
+typedef gfx::IntMarginTyped<LayoutDevicePixel> LayoutDeviceIntMargin;
+typedef gfx::IntRegionTyped<LayoutDevicePixel> LayoutDeviceIntRegion;
+
+typedef gfx::CoordTyped<LayerPixel> LayerCoord;
+typedef gfx::IntCoordTyped<LayerPixel> LayerIntCoord;
+typedef gfx::PointTyped<LayerPixel> LayerPoint;
+typedef gfx::IntPointTyped<LayerPixel> LayerIntPoint;
+typedef gfx::SizeTyped<LayerPixel> LayerSize;
+typedef gfx::IntSizeTyped<LayerPixel> LayerIntSize;
+typedef gfx::RectTyped<LayerPixel> LayerRect;
+typedef gfx::RectAbsoluteTyped<LayerPixel> LayerRectAbsolute;
+typedef gfx::IntRectTyped<LayerPixel> LayerIntRect;
+typedef gfx::MarginTyped<LayerPixel> LayerMargin;
+typedef gfx::IntMarginTyped<LayerPixel> LayerIntMargin;
+typedef gfx::IntRegionTyped<LayerPixel> LayerIntRegion;
+
+typedef gfx::CoordTyped<CSSTransformedLayerPixel> CSSTransformedLayerCoord;
+typedef gfx::IntCoordTyped<CSSTransformedLayerPixel>
+    CSSTransformedLayerIntCoord;
+typedef gfx::PointTyped<CSSTransformedLayerPixel> CSSTransformedLayerPoint;
+typedef gfx::IntPointTyped<CSSTransformedLayerPixel>
+    CSSTransformedLayerIntPoint;
+typedef gfx::SizeTyped<CSSTransformedLayerPixel> CSSTransformedLayerSize;
+typedef gfx::IntSizeTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntSize;
+typedef gfx::RectTyped<CSSTransformedLayerPixel> CSSTransformedLayerRect;
+typedef gfx::IntRectTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntRect;
+typedef gfx::MarginTyped<CSSTransformedLayerPixel> CSSTransformedLayerMargin;
+typedef gfx::IntMarginTyped<CSSTransformedLayerPixel>
+    CSSTransformedLayerIntMargin;
+typedef gfx::IntRegionTyped<CSSTransformedLayerPixel>
+    CSSTransformedLayerIntRegion;
+
+typedef gfx::PointTyped<RenderTargetPixel> RenderTargetPoint;
+typedef gfx::IntPointTyped<RenderTargetPixel> RenderTargetIntPoint;
+typedef gfx::SizeTyped<RenderTargetPixel> RenderTargetSize;
+typedef gfx::IntSizeTyped<RenderTargetPixel> RenderTargetIntSize;
+typedef gfx::RectTyped<RenderTargetPixel> RenderTargetRect;
+typedef gfx::IntRectTyped<RenderTargetPixel> RenderTargetIntRect;
+typedef gfx::MarginTyped<RenderTargetPixel> RenderTargetMargin;
+typedef gfx::IntMarginTyped<RenderTargetPixel> RenderTargetIntMargin;
+typedef gfx::IntRegionTyped<RenderTargetPixel> RenderTargetIntRegion;
+
+typedef gfx::PointTyped<ImagePixel> ImagePoint;
+typedef gfx::IntPointTyped<ImagePixel> ImageIntPoint;
+typedef gfx::SizeTyped<ImagePixel> ImageSize;
+typedef gfx::IntSizeTyped<ImagePixel> ImageIntSize;
+typedef gfx::RectTyped<ImagePixel> ImageRect;
+typedef gfx::IntRectTyped<ImagePixel> ImageIntRect;
+
+typedef gfx::CoordTyped<ScreenPixel> ScreenCoord;
+typedef gfx::IntCoordTyped<ScreenPixel> ScreenIntCoord;
+typedef gfx::PointTyped<ScreenPixel> ScreenPoint;
+typedef gfx::IntPointTyped<ScreenPixel> ScreenIntPoint;
+typedef gfx::SizeTyped<ScreenPixel> ScreenSize;
+typedef gfx::IntSizeTyped<ScreenPixel> ScreenIntSize;
+typedef gfx::RectTyped<ScreenPixel> ScreenRect;
+typedef gfx::IntRectTyped<ScreenPixel> ScreenIntRect;
+typedef gfx::MarginTyped<ScreenPixel> ScreenMargin;
+typedef gfx::IntMarginTyped<ScreenPixel> ScreenIntMargin;
+typedef gfx::IntRegionTyped<ScreenPixel> ScreenIntRegion;
+
+typedef gfx::CoordTyped<ParentLayerPixel> ParentLayerCoord;
+typedef gfx::IntCoordTyped<ParentLayerPixel> ParentLayerIntCoord;
+typedef gfx::PointTyped<ParentLayerPixel> ParentLayerPoint;
+typedef gfx::IntPointTyped<ParentLayerPixel> ParentLayerIntPoint;
+typedef gfx::SizeTyped<ParentLayerPixel> ParentLayerSize;
+typedef gfx::IntSizeTyped<ParentLayerPixel> ParentLayerIntSize;
+typedef gfx::RectTyped<ParentLayerPixel> ParentLayerRect;
+typedef gfx::IntRectTyped<ParentLayerPixel> ParentLayerIntRect;
+typedef gfx::MarginTyped<ParentLayerPixel> ParentLayerMargin;
+typedef gfx::IntMarginTyped<ParentLayerPixel> ParentLayerIntMargin;
+typedef gfx::IntRegionTyped<ParentLayerPixel> ParentLayerIntRegion;
+
+typedef gfx::CoordTyped<DesktopPixel> DesktopCoord;
+typedef gfx::IntCoordTyped<DesktopPixel> DesktopIntCoord;
+typedef gfx::PointTyped<DesktopPixel> DesktopPoint;
+typedef gfx::IntPointTyped<DesktopPixel> DesktopIntPoint;
+typedef gfx::SizeTyped<DesktopPixel> DesktopSize;
+typedef gfx::IntSizeTyped<DesktopPixel> DesktopIntSize;
+typedef gfx::RectTyped<DesktopPixel> DesktopRect;
+typedef gfx::IntRectTyped<DesktopPixel> DesktopIntRect;
+
+typedef gfx::CoordTyped<ExternalPixel> ExternalCoord;
+typedef gfx::IntCoordTyped<ExternalPixel> ExternalIntCoord;
+typedef gfx::PointTyped<ExternalPixel> ExternalPoint;
+typedef gfx::IntPointTyped<ExternalPixel> ExternalIntPoint;
+typedef gfx::SizeTyped<ExternalPixel> ExternalSize;
+typedef gfx::IntSizeTyped<ExternalPixel> ExternalIntSize;
+typedef gfx::RectTyped<ExternalPixel> ExternalRect;
+typedef gfx::IntRectTyped<ExternalPixel> ExternalIntRect;
+typedef gfx::MarginTyped<ExternalPixel> ExternalMargin;
+typedef gfx::IntMarginTyped<ExternalPixel> ExternalIntMargin;
+typedef gfx::IntRegionTyped<ExternalPixel> ExternalIntRegion;
+
+typedef gfx::ScaleFactor<CSSPixel, CSSPixel> CSSToCSSScale;
+typedef gfx::ScaleFactor<CSSPixel, LayoutDevicePixel> CSSToLayoutDeviceScale;
+typedef gfx::ScaleFactor<CSSPixel, LayerPixel> CSSToLayerScale;
+typedef gfx::ScaleFactor<CSSPixel, ScreenPixel> CSSToScreenScale;
+typedef gfx::ScaleFactor<CSSPixel, ParentLayerPixel> CSSToParentLayerScale;
+typedef gfx::ScaleFactor<CSSPixel, DesktopPixel> CSSToDesktopScale;
+typedef gfx::ScaleFactor<LayoutDevicePixel, CSSPixel> LayoutDeviceToCSSScale;
+typedef gfx::ScaleFactor<LayoutDevicePixel, LayerPixel>
+    LayoutDeviceToLayerScale;
+typedef gfx::ScaleFactor<LayoutDevicePixel, ScreenPixel>
+    LayoutDeviceToScreenScale;
+typedef gfx::ScaleFactor<LayoutDevicePixel, ParentLayerPixel>
+    LayoutDeviceToParentLayerScale;
+typedef gfx::ScaleFactor<LayerPixel, CSSPixel> LayerToCSSScale;
+typedef gfx::ScaleFactor<LayerPixel, LayoutDevicePixel>
+    LayerToLayoutDeviceScale;
+typedef gfx::ScaleFactor<LayerPixel, RenderTargetPixel>
+    LayerToRenderTargetScale;
+typedef gfx::ScaleFactor<LayerPixel, ScreenPixel> LayerToScreenScale;
+typedef gfx::ScaleFactor<LayerPixel, ParentLayerPixel> LayerToParentLayerScale;
+typedef gfx::ScaleFactor<RenderTargetPixel, ScreenPixel>
+    RenderTargetToScreenScale;
+typedef gfx::ScaleFactor<ScreenPixel, CSSPixel> ScreenToCSSScale;
+typedef gfx::ScaleFactor<ScreenPixel, LayoutDevicePixel>
+    ScreenToLayoutDeviceScale;
+typedef gfx::ScaleFactor<ScreenPixel, LayerPixel> ScreenToLayerScale;
+typedef gfx::ScaleFactor<ScreenPixel, ParentLayerPixel>
+    ScreenToParentLayerScale;
+typedef gfx::ScaleFactor<ParentLayerPixel, LayerPixel> ParentLayerToLayerScale;
+typedef gfx::ScaleFactor<ParentLayerPixel, ScreenPixel>
+    ParentLayerToScreenScale;
+typedef gfx::ScaleFactor<ParentLayerPixel, ParentLayerPixel>
+    ParentLayerToParentLayerScale;
+typedef gfx::ScaleFactor<DesktopPixel, LayoutDevicePixel>
+    DesktopToLayoutDeviceScale;
+typedef gfx::ScaleFactor<LayoutDevicePixel, DesktopPixel>
+    LayoutDeviceToDesktopScale;
+
+typedef gfx::ScaleFactors2D<CSSPixel, LayoutDevicePixel>
+    CSSToLayoutDeviceScale2D;
+typedef gfx::ScaleFactors2D<CSSPixel, LayerPixel> CSSToLayerScale2D;
+typedef gfx::ScaleFactors2D<CSSPixel, ScreenPixel> CSSToScreenScale2D;
+typedef gfx::ScaleFactors2D<CSSPixel, ParentLayerPixel> CSSToParentLayerScale2D;
+typedef gfx::ScaleFactors2D<LayoutDevicePixel, CSSPixel>
+    LayoutDeviceToCSSScale2D;
+typedef gfx::ScaleFactors2D<LayoutDevicePixel, LayerPixel>
+    LayoutDeviceToLayerScale2D;
+typedef gfx::ScaleFactors2D<LayoutDevicePixel, ScreenPixel>
+    LayoutDeviceToScreenScale2D;
+typedef gfx::ScaleFactors2D<LayoutDevicePixel, ParentLayerPixel>
+    LayoutDeviceToParentLayerScale2D;
+typedef gfx::ScaleFactors2D<LayerPixel, CSSPixel> LayerToCSSScale2D;
+typedef gfx::ScaleFactors2D<LayerPixel, LayoutDevicePixel>
+    LayerToLayoutDeviceScale2D;
+typedef gfx::ScaleFactors2D<LayerPixel, RenderTargetPixel>
+    LayerToRenderTargetScale2D;
+typedef gfx::ScaleFactors2D<LayerPixel, ScreenPixel> LayerToScreenScale2D;
+typedef gfx::ScaleFactors2D<LayerPixel, ParentLayerPixel>
+    LayerToParentLayerScale2D;
+typedef gfx::ScaleFactors2D<RenderTargetPixel, ScreenPixel>
+    RenderTargetToScreenScale2D;
+typedef gfx::ScaleFactors2D<ScreenPixel, CSSPixel> ScreenToCSSScale2D;
+typedef gfx::ScaleFactors2D<ScreenPixel, LayoutDevicePixel>
+    ScreenToLayoutDeviceScale2D;
+typedef gfx::ScaleFactors2D<ScreenPixel, ScreenPixel> ScreenToScreenScale2D;
+typedef gfx::ScaleFactors2D<ScreenPixel, LayerPixel> ScreenToLayerScale2D;
+typedef gfx::ScaleFactors2D<ScreenPixel, ParentLayerPixel>
+    ScreenToParentLayerScale2D;
+typedef gfx::ScaleFactors2D<ParentLayerPixel, LayerPixel>
+    ParentLayerToLayerScale2D;
+typedef gfx::ScaleFactors2D<ParentLayerPixel, ScreenPixel>
+    ParentLayerToScreenScale2D;
+typedef gfx::ScaleFactors2D<ParentLayerPixel, ParentLayerPixel>
+    ParentLayerToParentLayerScale2D;
+typedef gfx::ScaleFactors2D<gfx::UnknownUnits, gfx::UnknownUnits> Scale2D;
+
+typedef gfx::Matrix4x4Typed<CSSPixel, CSSPixel> CSSToCSSMatrix4x4;
+typedef gfx::Matrix4x4Typed<LayoutDevicePixel, LayoutDevicePixel>
+    LayoutDeviceToLayoutDeviceMatrix4x4;
+typedef gfx::Matrix4x4Typed<LayoutDevicePixel, ParentLayerPixel>
+    LayoutDeviceToParentLayerMatrix4x4;
+typedef gfx::Matrix4x4Typed<LayerPixel, ParentLayerPixel>
+    LayerToParentLayerMatrix4x4;
+typedef gfx::Matrix4x4Typed<LayerPixel, ScreenPixel> LayerToScreenMatrix4x4;
+typedef gfx::Matrix4x4Typed<ScreenPixel, ScreenPixel> ScreenToScreenMatrix4x4;
+typedef gfx::Matrix4x4Typed<ScreenPixel, ParentLayerPixel>
+    ScreenToParentLayerMatrix4x4;
+typedef gfx::Matrix4x4Typed<ParentLayerPixel, LayerPixel>
+    ParentLayerToLayerMatrix4x4;
+typedef gfx::Matrix4x4Typed<ParentLayerPixel, ScreenPixel>
+    ParentLayerToScreenMatrix4x4;
+typedef gfx::Matrix4x4Typed<ParentLayerPixel, ParentLayerPixel>
+    ParentLayerToParentLayerMatrix4x4;
+typedef gfx::Matrix4x4Typed<ParentLayerPixel, RenderTargetPixel>
+    ParentLayerToRenderTargetMatrix4x4;
+typedef gfx::Matrix4x4Typed<ExternalPixel, ParentLayerPixel>
+    ExternalToParentLayerMatrix4x4;
+
+/*
+ * The pixels that content authors use to specify sizes in.
+ */
+struct CSSPixel {
+  // Conversions from app units
+  static CSSCoord FromAppUnits(nscoord aCoord) {
+    return NSAppUnitsToFloatPixels(aCoord, float(AppUnitsPerCSSPixel()));
+  }
+
+  static CSSIntCoord FromAppUnitsRounded(nscoord aCoord) {
+    return NSAppUnitsToIntPixels(aCoord, float(AppUnitsPerCSSPixel()));
+  }
+
+  static CSSPoint FromAppUnits(const nsPoint& aPoint) {
+    return CSSPoint(FromAppUnits(aPoint.x), FromAppUnits(aPoint.y));
+  }
+
+  static CSSSize FromAppUnits(const nsSize& aSize) {
+    return CSSSize(FromAppUnits(aSize.width), FromAppUnits(aSize.height));
+  }
+
+  static CSSRect FromAppUnits(const nsRect& aRect) {
+    return CSSRect(FromAppUnits(aRect.x), FromAppUnits(aRect.y),
+                   FromAppUnits(aRect.Width()), FromAppUnits(aRect.Height()));
+  }
+
+  static CSSMargin FromAppUnits(const nsMargin& aMargin) {
+    return CSSMargin(FromAppUnits(aMargin.top), FromAppUnits(aMargin.right),
+                     FromAppUnits(aMargin.bottom), FromAppUnits(aMargin.left));
+  }
+
+  static CSSIntPoint FromAppUnitsRounded(const nsPoint& aPoint) {
+    return CSSIntPoint(FromAppUnitsRounded(aPoint.x),
+                       FromAppUnitsRounded(aPoint.y));
+  }
+
+  static CSSIntSize FromAppUnitsRounded(const nsSize& aSize) {
+    return CSSIntSize(FromAppUnitsRounded(aSize.width),
+                      FromAppUnitsRounded(aSize.height));
+  }
+
+  static CSSIntRect FromAppUnitsRounded(const nsRect& aRect) {
+    return CSSIntRect(FromAppUnitsRounded(aRect.x),
+                      FromAppUnitsRounded(aRect.y),
+                      FromAppUnitsRounded(aRect.Width()),
+                      FromAppUnitsRounded(aRect.Height()));
+  }
+
+  static CSSIntMargin FromAppUnitsRounded(const nsMargin& aMargin) {
+    return CSSIntMargin(
+        FromAppUnitsRounded(aMargin.top), FromAppUnitsRounded(aMargin.right),
+        FromAppUnitsRounded(aMargin.bottom), FromAppUnitsRounded(aMargin.left));
+  }
+
+  static CSSIntRect FromAppUnitsToNearest(const nsRect& aRect) {
+    return CSSIntRect::FromUnknownRect(
+        aRect.ToNearestPixels(AppUnitsPerCSSPixel()));
+  }
+
+  static CSSIntRect FromAppUnitsToInside(const nsRect& aRect) {
+    return CSSIntRect::FromUnknownRect(
+        aRect.ToInsidePixels(AppUnitsPerCSSPixel()));
+  }
+
+  // Conversions to app units
+
+  // TODO: We might want an int32_t/CSSIntCoord overload which doesn't do float
+  // math but we'd need to ensure stuff is clamped to nscoord_MIN/MAX range.
+  static nscoord ToAppUnits(CSSCoord aCoord) {
+    return NSFloatPixelsToAppUnits(aCoord, AppUnitsPerCSSPixel());
+  }
+
+  static nsPoint ToAppUnits(const CSSPoint& aPoint) {
+    return nsPoint(ToAppUnits(aPoint.x), ToAppUnits(aPoint.y));
+  }
+
+  static nsPoint ToAppUnits(const CSSIntPoint& aPoint) {
+    return nsPoint(ToAppUnits(CSSCoord(aPoint.x)),
+                   ToAppUnits(CSSCoord(aPoint.y)));
+  }
+
+  static nsSize ToAppUnits(const CSSSize& aSize) {
+    return nsSize(ToAppUnits(aSize.width), ToAppUnits(aSize.height));
+  }
+
+  static nsSize ToAppUnits(const CSSIntSize& aSize) {
+    return nsSize(ToAppUnits(aSize.width), ToAppUnits(aSize.height));
+  }
+
+  static nsRect ToAppUnits(const CSSRect& aRect) {
+    return nsRect(ToAppUnits(aRect.x), ToAppUnits(aRect.y),
+                  ToAppUnits(aRect.Width()), ToAppUnits(aRect.Height()));
+  }
+
+  static nsRect ToAppUnits(const CSSIntRect& aRect) {
+    return nsRect(ToAppUnits(aRect.x), ToAppUnits(aRect.y),
+                  ToAppUnits(aRect.Width()), ToAppUnits(aRect.Height()));
+  }
+
+  static nsMargin ToAppUnits(const CSSMargin& aMargin) {
+    return nsMargin(ToAppUnits(aMargin.top), ToAppUnits(aMargin.right),
+                    ToAppUnits(aMargin.bottom), ToAppUnits(aMargin.left));
+  }
+
+  static nsMargin ToAppUnits(const CSSIntMargin& aMargin) {
+    return nsMargin(ToAppUnits(aMargin.top), ToAppUnits(aMargin.right),
+                    ToAppUnits(aMargin.bottom), ToAppUnits(aMargin.left));
+  }
+
+  // Conversion from a given CSS point value.
+  static CSSCoord FromPoints(float aCoord) {
+    // One inch / 72.
+    return aCoord * 96.0f / 72.0f;
+  }
+};
+
+/*
+ * The pixels that are referred to as "device pixels" in layout code. In
+ * general values measured in LayoutDevicePixels are obtained by dividing a
+ * value in app units by AppUnitsPerDevPixel(). Conversion between CSS pixels
+ * and LayoutDevicePixels is affected by:
+ * 1) the "full zoom" (see nsPresContext::SetFullZoom)
+ * 2) the "widget scale" (see nsIWidget::GetDefaultScale)
+ */
+struct LayoutDevicePixel {
+  static LayoutDeviceCoord FromAppUnits(nscoord aCoord,
+                                        nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceCoord(
+        NSAppUnitsToFloatPixels(aCoord, float(aAppUnitsPerDevPixel)));
+  }
+
+  static LayoutDeviceIntCoord FromAppUnitsRounded(
+      nscoord aCoord, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntCoord(
+        NSAppUnitsToIntPixels(aCoord, float(aAppUnitsPerDevPixel)));
+  }
+
+  static LayoutDeviceRect FromAppUnits(const nsRect& aRect,
+                                       nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceRect(FromAppUnits(aRect.x, aAppUnitsPerDevPixel),
+                            FromAppUnits(aRect.y, aAppUnitsPerDevPixel),
+                            FromAppUnits(aRect.Width(), aAppUnitsPerDevPixel),
+                            FromAppUnits(aRect.Height(), aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceSize FromAppUnits(const nsSize& aSize,
+                                       nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceSize(FromAppUnits(aSize.width, aAppUnitsPerDevPixel),
+                            FromAppUnits(aSize.height, aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDevicePoint FromAppUnits(const nsPoint& aPoint,
+                                        nscoord aAppUnitsPerDevPixel) {
+    return LayoutDevicePoint(FromAppUnits(aPoint.x, aAppUnitsPerDevPixel),
+                             FromAppUnits(aPoint.y, aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceMargin FromAppUnits(const nsMargin& aMargin,
+                                         nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceMargin(
+        FromAppUnits(aMargin.top, aAppUnitsPerDevPixel),
+        FromAppUnits(aMargin.right, aAppUnitsPerDevPixel),
+        FromAppUnits(aMargin.bottom, aAppUnitsPerDevPixel),
+        FromAppUnits(aMargin.left, aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntPoint FromAppUnitsRounded(
+      const nsPoint& aPoint, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntPoint(
+        FromAppUnitsRounded(aPoint.x, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aPoint.y, aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntRect FromAppUnitsRounded(const nsRect& aRect,
+                                                 nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntRect(
+        FromAppUnitsRounded(aRect.x, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aRect.y, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aRect.Width(), aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aRect.Height(), aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntPoint FromAppUnitsToNearest(
+      const nsPoint& aPoint, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntPoint::FromUnknownPoint(
+        aPoint.ToNearestPixels(aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntRect FromAppUnitsToNearest(
+      const nsRect& aRect, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntRect::FromUnknownRect(
+        aRect.ToNearestPixels(aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntRect FromAppUnitsToInside(
+      const nsRect& aRect, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntRect::FromUnknownRect(
+        aRect.ToInsidePixels(aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntRect FromAppUnitsToOutside(
+      const nsRect& aRect, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntRect::FromUnknownRect(
+        aRect.ToOutsidePixels(aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntSize FromAppUnitsRounded(const nsSize& aSize,
+                                                 nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntSize(
+        FromAppUnitsRounded(aSize.width, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aSize.height, aAppUnitsPerDevPixel));
+  }
+
+  static LayoutDeviceIntMargin FromAppUnitsRounded(
+      const nsMargin& aMargin, nscoord aAppUnitsPerDevPixel) {
+    return LayoutDeviceIntMargin(
+        FromAppUnitsRounded(aMargin.top, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aMargin.right, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aMargin.bottom, aAppUnitsPerDevPixel),
+        FromAppUnitsRounded(aMargin.left, aAppUnitsPerDevPixel));
+  }
+
+  static nscoord ToAppUnits(LayoutDeviceIntCoord aCoord,
+                            nscoord aAppUnitsPerDevPixel) {
+    return aCoord * aAppUnitsPerDevPixel;
+  }
+
+  static nscoord ToAppUnits(int32_t aCoord, nscoord aAppUnitsPerDevPixel) {
+    return ToAppUnits(LayoutDeviceIntCoord(aCoord), aAppUnitsPerDevPixel);
+  }
+
+  static nscoord ToAppUnits(LayoutDeviceCoord aCoord,
+                            nscoord aAppUnitsPerDevPixel) {
+    return NSFloatPixelsToAppUnits(aCoord, aAppUnitsPerDevPixel);
+  }
+
+  static nscoord ToAppUnits(float aCoord, nscoord aAppUnitsPerDevPixel) {
+    return ToAppUnits(LayoutDeviceCoord(aCoord), aAppUnitsPerDevPixel);
+  }
+
+  static nsPoint ToAppUnits(const LayoutDeviceIntPoint& aPoint,
+                            nscoord aAppUnitsPerDevPixel) {
+    return nsPoint(ToAppUnits(aPoint.x, aAppUnitsPerDevPixel),
+                   ToAppUnits(aPoint.y, aAppUnitsPerDevPixel));
+  }
+
+  static nsSize ToAppUnits(const LayoutDeviceIntSize& aSize,
+                           nscoord aAppUnitsPerDevPixel) {
+    return nsSize(ToAppUnits(aSize.width, aAppUnitsPerDevPixel),
+                  ToAppUnits(aSize.height, aAppUnitsPerDevPixel));
+  }
+
+  static nsSize ToAppUnits(const LayoutDeviceSize& aSize,
+                           nscoord aAppUnitsPerDevPixel) {
+    return nsSize(ToAppUnits(aSize.width, aAppUnitsPerDevPixel),
+                  ToAppUnits(aSize.height, aAppUnitsPerDevPixel));
+  }
+
+  static nsRect ToAppUnits(const LayoutDeviceIntRect& aRect,
+                           nscoord aAppUnitsPerDevPixel) {
+    return nsRect(ToAppUnits(aRect.x, aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.y, aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.Width(), aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.Height(), aAppUnitsPerDevPixel));
+  }
+
+  static nsRect ToAppUnits(const LayoutDeviceRect& aRect,
+                           nscoord aAppUnitsPerDevPixel) {
+    return nsRect(ToAppUnits(aRect.x, aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.y, aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.Width(), aAppUnitsPerDevPixel),
+                  ToAppUnits(aRect.Height(), aAppUnitsPerDevPixel));
+  }
+
+  static nsMargin ToAppUnits(const LayoutDeviceIntMargin& aMargin,
+                             nscoord aAppUnitsPerDevPixel) {
+    return nsMargin(ToAppUnits(aMargin.top, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.right, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.bottom, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.left, aAppUnitsPerDevPixel));
+  }
+
+  static nsMargin ToAppUnits(const LayoutDeviceMargin& aMargin,
+                             nscoord aAppUnitsPerDevPixel) {
+    return nsMargin(ToAppUnits(aMargin.top, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.right, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.bottom, aAppUnitsPerDevPixel),
+                    ToAppUnits(aMargin.left, aAppUnitsPerDevPixel));
+  }
+};
+
+/*
+ * The pixels that layout rasterizes and delivers to the graphics code.
+ * These also are generally referred to as "device pixels" in layout code.
+ * Conversion between CSS pixels and LayerPixels is affected by:
+ * 1) the "display resolution" (see PresShell::SetResolution)
+ * 2) the "full zoom" (see nsPresContext::SetFullZoom)
+ * 3) the "widget scale" (see nsIWidget::GetDefaultScale)
+ * 4) rasterizing at a different scale in the presence of some CSS transforms
+ */
+struct LayerPixel {};
+
+/*
+ * This is Layer coordinates with the Layer's CSS transform applied.
+ * It can be thought of as intermediate between LayerPixel and
+ * ParentLayerPixel, as further applying async transforms to this
+ * yields ParentLayerPixels.
+ */
+struct CSSTransformedLayerPixel {};
+
+/*
+ * Layers are always composited to a render target. This unit
+ * represents one pixel in the render target. Note that for the
+ * root render target RenderTargetPixel == ScreenPixel. Also
+ * any ContainerLayer providing an intermediate surface will
+ * have RenderTargetPixel == LayerPixel.
+ */
+struct RenderTargetPixel {};
+
+/*
+ * This unit represents one pixel in an image. Image space
+ * is largely independent of any other space.
+ */
+struct ImagePixel {};
+
+/*
+ * The pixels that are displayed on the screen.
+ * On non-OMTC platforms this should be equivalent to LayerPixel units.
+ * On OMTC platforms these may diverge from LayerPixel units temporarily,
+ * while an asynchronous zoom is happening, but should eventually converge
+ * back to LayerPixel units. Some variables (such as those representing
+ * chrome UI element sizes) that are not subject to content zoom should
+ * generally be represented in ScreenPixel units.
+ */
+struct ScreenPixel {};
+
+/* The layer coordinates of the parent frame.
+ * This can be arrived at in three ways:
+ *   - Start with the CSS coordinates of the parent frame, multiply by the
+ *     device scale and the cumulative resolution of the parent frame.
+ *   - Start with the CSS coordinates of current frame, multiply by the device
+ *     scale, the cumulative resolution of the current frame, and the scales
+ *     from the CSS and async transforms of the current frame.
+ *   - Start with global screen coordinates and unapply all CSS and async
+ *     transforms from the root down to and including the parent.
+ * It's helpful to look at
+ * https://wiki.mozilla.org/Platform/GFX/APZ#Coordinate_systems to get a picture
+ * of how the various coordinate systems relate to each other.
+ */
+struct ParentLayerPixel {};
+
+/*
+ * Pixels in the coordinate space used by the host OS to manage windows on the
+ * desktop. What these mean varies between OSs:
+ * - by default (unless implemented differently in platform-specific widget
+ *   code) they are the same as LayoutDevicePixels
+ * - on Mac OS X, they're "cocoa points", which correspond to device pixels
+ *   on a non-Retina display, and to 2x device pixels on Retina
+ * - on Windows *without* per-monitor DPI support, they are Windows "logical
+ *   pixels", i.e. device pixels scaled according to the Windows display DPI
+ *   scaling factor (typically one of 1.25, 1.5, 1.75, 2.0...)
+ * - on Windows *with* per-monitor DPI support, they are physical device pixels
+ *   on each screen; note that this means the scaling between CSS pixels and
+ *   desktop pixels may vary across multiple displays.
+ */
+struct DesktopPixel {};
+
+struct ExternalPixel {};
+
+// Operators to apply ScaleFactors directly to Coords, Points, Rects, Sizes and
+// Margins
+
+template <class Src, class Dst>
+gfx::CoordTyped<Dst> operator*(const gfx::CoordTyped<Src>& aCoord,
+                               const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::CoordTyped<Dst>(aCoord.value * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::CoordTyped<Dst> operator/(const gfx::CoordTyped<Src>& aCoord,
+                               const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::CoordTyped<Dst>(aCoord.value / aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::PointTyped<Dst> operator*(const gfx::PointTyped<Src>& aPoint,
+                               const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::PointTyped<Dst>(aPoint.x * aScale.scale, aPoint.y * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::PointTyped<Dst> operator/(const gfx::PointTyped<Src>& aPoint,
+                               const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::PointTyped<Dst>(aPoint.x / aScale.scale, aPoint.y / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::PointTyped<Dst, F> operator*(
+    const gfx::PointTyped<Src, F>& aPoint,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::PointTyped<Dst, F>(aPoint.x * aScale.xScale,
+                                 aPoint.y * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::PointTyped<Dst, F> operator/(
+    const gfx::PointTyped<Src, F>& aPoint,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::PointTyped<Dst, F>(aPoint.x / aScale.xScale,
+                                 aPoint.y / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::PointTyped<Dst> operator*(const gfx::IntPointTyped<Src>& aPoint,
+                               const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::PointTyped<Dst>(float(aPoint.x) * aScale.scale,
+                              float(aPoint.y) * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::PointTyped<Dst> operator/(const gfx::IntPointTyped<Src>& aPoint,
+                               const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::PointTyped<Dst>(float(aPoint.x) / aScale.scale,
+                              float(aPoint.y) / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::PointTyped<Dst, F> operator*(
+    const gfx::IntPointTyped<Src>& aPoint,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::PointTyped<Dst, F>(F(aPoint.x) * aScale.xScale,
+                                 F(aPoint.y) * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::PointTyped<Dst, F> operator/(
+    const gfx::IntPointTyped<Src>& aPoint,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::PointTyped<Dst, F>(F(aPoint.x) / aScale.xScale,
+                                 F(aPoint.y) / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::RectTyped<Dst> operator*(const gfx::RectTyped<Src>& aRect,
+                              const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::RectTyped<Dst>(aRect.x * aScale.scale, aRect.y * aScale.scale,
+                             aRect.Width() * aScale.scale,
+                             aRect.Height() * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::RectTyped<Dst> operator/(const gfx::RectTyped<Src>& aRect,
+                              const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::RectTyped<Dst>(aRect.x / aScale.scale, aRect.y / aScale.scale,
+                             aRect.Width() / aScale.scale,
+                             aRect.Height() / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::RectTyped<Dst, F> operator*(
+    const gfx::RectTyped<Src, F>& aRect,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::RectTyped<Dst, F>(
+      aRect.x * aScale.xScale, aRect.y * aScale.yScale,
+      aRect.Width() * aScale.xScale, aRect.Height() * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::RectTyped<Dst, F> operator/(
+    const gfx::RectTyped<Src, F>& aRect,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::RectTyped<Dst, F>(
+      aRect.x / aScale.xScale, aRect.y / aScale.yScale,
+      aRect.Width() / aScale.xScale, aRect.Height() / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::RectTyped<Dst> operator*(const gfx::IntRectTyped<Src>& aRect,
+                              const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::RectTyped<Dst>(float(aRect.x) * aScale.scale,
+                             float(aRect.y) * aScale.scale,
+                             float(aRect.Width()) * aScale.scale,
+                             float(aRect.Height()) * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::RectTyped<Dst> operator/(const gfx::IntRectTyped<Src>& aRect,
+                              const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::RectTyped<Dst>(float(aRect.x) / aScale.scale,
+                             float(aRect.y) / aScale.scale,
+                             float(aRect.Width()) / aScale.scale,
+                             float(aRect.Height()) / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::RectTyped<Dst, F> operator*(
+    const gfx::IntRectTyped<Src>& aRect,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::RectTyped<Dst, F>(
+      F(aRect.x) * aScale.xScale, F(aRect.y) * aScale.yScale,
+      F(aRect.Width()) * aScale.xScale, F(aRect.Height()) * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::RectTyped<Dst, F> operator/(
+    const gfx::IntRectTyped<Src>& aRect,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::RectTyped<Dst, F>(
+      F(aRect.x) / aScale.xScale, F(aRect.y) / aScale.yScale,
+      F(aRect.Width()) / aScale.xScale, F(aRect.Height()) / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::SizeTyped<Dst> operator*(const gfx::SizeTyped<Src>& aSize,
+                              const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::SizeTyped<Dst>(aSize.width * aScale.scale,
+                             aSize.height * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::SizeTyped<Dst> operator/(const gfx::SizeTyped<Src>& aSize,
+                              const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::SizeTyped<Dst>(aSize.width / aScale.scale,
+                             aSize.height / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::SizeTyped<Dst, F> operator*(
+    const gfx::SizeTyped<Src, F>& aSize,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::SizeTyped<Dst, F>(aSize.width * aScale.xScale,
+                                aSize.height * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::SizeTyped<Dst, F> operator/(
+    const gfx::SizeTyped<Src, F>& aSize,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::SizeTyped<Dst, F>(aSize.width / aScale.xScale,
+                                aSize.height / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::SizeTyped<Dst> operator*(const gfx::IntSizeTyped<Src>& aSize,
+                              const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::SizeTyped<Dst>(float(aSize.width) * aScale.scale,
+                             float(aSize.height) * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::SizeTyped<Dst> operator/(const gfx::IntSizeTyped<Src>& aSize,
+                              const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::SizeTyped<Dst>(float(aSize.width) / aScale.scale,
+                             float(aSize.height) / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::SizeTyped<Dst, F> operator*(
+    const gfx::IntSizeTyped<Src>& aSize,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::SizeTyped<Dst, F>(F(aSize.width) * aScale.xScale,
+                                F(aSize.height) * aScale.yScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::SizeTyped<Dst, F> operator/(
+    const gfx::IntSizeTyped<Src>& aSize,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::SizeTyped<Dst, F>(F(aSize.width) / aScale.xScale,
+                                F(aSize.height) / aScale.yScale);
+}
+
+template <class Src, class Dst>
+gfx::MarginTyped<Dst> operator*(const gfx::MarginTyped<Src>& aMargin,
+                                const gfx::ScaleFactor<Src, Dst>& aScale) {
+  return gfx::MarginTyped<Dst>(
+      aMargin.top * aScale.scale, aMargin.right * aScale.scale,
+      aMargin.bottom * aScale.scale, aMargin.left * aScale.scale);
+}
+
+template <class Src, class Dst>
+gfx::MarginTyped<Dst> operator/(const gfx::MarginTyped<Src>& aMargin,
+                                const gfx::ScaleFactor<Dst, Src>& aScale) {
+  return gfx::MarginTyped<Dst>(
+      aMargin.top / aScale.scale, aMargin.right / aScale.scale,
+      aMargin.bottom / aScale.scale, aMargin.left / aScale.scale);
+}
+
+template <class Src, class Dst, class F>
+gfx::MarginTyped<Dst, F> operator*(
+    const gfx::MarginTyped<Src, F>& aMargin,
+    const gfx::BaseScaleFactors2D<Src, Dst, F>& aScale) {
+  return gfx::MarginTyped<Dst, F>(
+      aMargin.top * aScale.yScale, aMargin.right * aScale.xScale,
+      aMargin.bottom * aScale.yScale, aMargin.left * aScale.xScale);
+}
+
+template <class Src, class Dst, class F>
+gfx::MarginTyped<Dst, F> operator/(
+    const gfx::MarginTyped<Src, F>& aMargin,
+    const gfx::BaseScaleFactors2D<Dst, Src, F>& aScale) {
+  return gfx::MarginTyped<Dst, F>(
+      aMargin.top / aScale.yScale, aMargin.right / aScale.xScale,
+      aMargin.bottom / aScale.yScale, aMargin.left / aScale.xScale);
+}
+
+// Calculate the max or min or the ratios of the widths and heights of two
+// sizes, returning a scale factor in the correct units.
+
+template <class Src, class Dst>
+gfx::ScaleFactor<Src, Dst> MaxScaleRatio(const gfx::SizeTyped<Dst>& aDestSize,
+                                         const gfx::SizeTyped<Src>& aSrcSize) {
+  MOZ_ASSERT(aSrcSize.width != 0 && aSrcSize.height != 0,
+             "Caller must verify aSrcSize has nonzero components, "
+             "to avoid division by 0 here");
+  return gfx::ScaleFactor<Src, Dst>(std::max(
+      aDestSize.width / aSrcSize.width, aDestSize.height / aSrcSize.height));
+}
+
+template <class Src, class Dst>
+gfx::ScaleFactor<Src, Dst> MinScaleRatio(const gfx::SizeTyped<Dst>& aDestSize,
+                                         const gfx::SizeTyped<Src>& aSrcSize) {
+  MOZ_ASSERT(aSrcSize.width != 0 && aSrcSize.height != 0,
+             "Caller must verify aSrcSize has nonzero components, "
+             "to avoid division by 0 here");
+  return gfx::ScaleFactor<Src, Dst>(std::min(
+      aDestSize.width / aSrcSize.width, aDestSize.height / aSrcSize.height));
+}
+
+template <typename T>
+struct CoordOfImpl;
+
+template <typename Units>
+struct CoordOfImpl<gfx::PointTyped<Units>> {
+  typedef gfx::CoordTyped<Units> Type;
+};
+
+template <typename Units>
+struct CoordOfImpl<gfx::IntPointTyped<Units>> {
+  typedef gfx::IntCoordTyped<Units> Type;
+};
+
+template <typename Units>
+struct CoordOfImpl<gfx::RectTyped<Units>> {
+  typedef gfx::CoordTyped<Units> Type;
+};
+
+template <typename Units>
+struct CoordOfImpl<gfx::IntRectTyped<Units>> {
+  typedef gfx::IntCoordTyped<Units> Type;
+};
+
+template <typename Units>
+struct CoordOfImpl<gfx::SizeTyped<Units>> {
+  typedef gfx::CoordTyped<Units> Type;
+};
+
+template <typename T>
+using CoordOf = typename CoordOfImpl<T>::Type;
+
+}  // namespace mozilla
+
+#endif