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diff --git a/gfx/2d/BaseRect.h b/gfx/2d/BaseRect.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_BASERECT_H_
+#define MOZILLA_GFX_BASERECT_H_
+
+#include <algorithm>
+#include <cmath>
+#include <ostream>
+#include <type_traits>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/gfx/ScaleFactors2D.h"
+#include "Types.h"
+
+namespace mozilla::gfx {
+
+/**
+ * Rectangles have two interpretations: a set of (zero-size) points,
+ * and a rectangular area of the plane. Most rectangle operations behave
+ * the same no matter what interpretation is being used, but some operations
+ * differ:
+ * -- Equality tests behave differently. When a rectangle represents an area,
+ * all zero-width and zero-height rectangles are equal to each other since they
+ * represent the empty area. But when a rectangle represents a set of
+ * mathematical points, zero-width and zero-height rectangles can be unequal.
+ * -- The union operation can behave differently. When rectangles represent
+ * areas, taking the union of a zero-width or zero-height rectangle with
+ * another rectangle can just ignore the empty rectangle. But when rectangles
+ * represent sets of mathematical points, we may need to extend the latter
+ * rectangle to include the points of a zero-width or zero-height rectangle.
+ *
+ * To ensure that these interpretations are explicitly disambiguated, we
+ * deny access to the == and != operators and require use of IsEqualEdges and
+ * IsEqualInterior instead. Similarly we provide separate Union and UnionEdges
+ * methods.
+ *
+ * Do not use this class directly. Subclass it, pass that subclass as the
+ * Sub parameter, and only use that subclass.
+ */
+template <class T, class Sub, class Point, class SizeT, class MarginT>
+struct BaseRect {
+  T x, y, width, height;
+
+  // Constructors
+  BaseRect() : x(0), y(0), width(0), height(0) {}
+  BaseRect(const Point& aOrigin, const SizeT& aSize)
+      : x(aOrigin.x), y(aOrigin.y), width(aSize.width), height(aSize.height) {}
+  BaseRect(T aX, T aY, T aWidth, T aHeight)
+      : x(aX), y(aY), width(aWidth), height(aHeight) {}
+
+  // Emptiness. An empty rect is one that has no area, i.e. its height or width
+  // is <= 0.  Zero rect is the one with height and width set to zero.  Note
+  // that SetEmpty() may change a rectangle that identified as IsEmpty().
+  MOZ_ALWAYS_INLINE bool IsZeroArea() const {
+    return height == 0 || width == 0;
+  }
+  MOZ_ALWAYS_INLINE bool IsEmpty() const { return height <= 0 || width <= 0; }
+  void SetEmpty() { width = height = 0; }
+
+  // "Finite" means not inf and not NaN
+  bool IsFinite() const {
+    using FloatType =
+        std::conditional_t<std::is_same_v<T, float>, float, double>;
+    return (std::isfinite(FloatType(x)) && std::isfinite(FloatType(y)) &&
+            std::isfinite(FloatType(width)) &&
+            std::isfinite(FloatType(height)));
+  }
+
+  // Returns true if this rectangle contains the interior of aRect. Always
+  // returns true if aRect is empty, and always returns false is aRect is
+  // nonempty but this rect is empty.
+  bool Contains(const Sub& aRect) const {
+    return aRect.IsEmpty() || (x <= aRect.x && aRect.XMost() <= XMost() &&
+                               y <= aRect.y && aRect.YMost() <= YMost());
+  }
+  // Returns true if this rectangle contains the point. Points are considered
+  // in the rectangle if they are on the left or top edge, but outside if they
+  // are on the right or bottom edge.
+  MOZ_ALWAYS_INLINE bool Contains(T aX, T aY) const {
+    return x <= aX && aX < XMost() && y <= aY && aY < YMost();
+  }
+  MOZ_ALWAYS_INLINE bool ContainsX(T aX) const {
+    return x <= aX && aX < XMost();
+  }
+  MOZ_ALWAYS_INLINE bool ContainsY(T aY) const {
+    return y <= aY && aY < YMost();
+  }
+  // Returns true if this rectangle contains the point. Points are considered
+  // in the rectangle if they are on the left or top edge, but outside if they
+  // are on the right or bottom edge.
+  bool Contains(const Point& aPoint) const {
+    return Contains(aPoint.x, aPoint.y);
+  }
+
+  // Returns true if this rectangle contains the point, considering points on
+  // all edges of the rectangle to be contained (as compared to Contains()
+  // which only includes points on the top & left but not bottom & right edges).
+  MOZ_ALWAYS_INLINE bool ContainsInclusively(const Point& aPoint) const {
+    return x <= aPoint.x && aPoint.x <= XMost() && y <= aPoint.y &&
+           aPoint.y <= YMost();
+  }
+
+  // Intersection. Returns TRUE if the receiver's area has non-empty
+  // intersection with aRect's area, and FALSE otherwise.
+  // Always returns false if aRect is empty or 'this' is empty.
+  bool Intersects(const Sub& aRect) const {
+    return !IsEmpty() && !aRect.IsEmpty() && x < aRect.XMost() &&
+           aRect.x < XMost() && y < aRect.YMost() && aRect.y < YMost();
+  }
+  // Returns the rectangle containing the intersection of the points
+  // (including edges) of *this and aRect. If there are no points in that
+  // intersection, returns an empty rectangle with x/y set to the std::max of
+  // the x/y of *this and aRect.
+  //
+  // Intersection with an empty Rect may not produce an empty Rect if overflow
+  // occurs. e.g. {INT_MIN, 0, 0, 20} Intersect { 5000, 0, 500, 20 } gives:
+  // the non-emtpy {5000, 0, 500, 20 } instead of {5000, 0, 0, 0}
+  [[nodiscard]] Sub Intersect(const Sub& aRect) const {
+    Sub result;
+    result.x = std::max<T>(x, aRect.x);
+    result.y = std::max<T>(y, aRect.y);
+    result.width =
+        std::min<T>(x - result.x + width, aRect.x - result.x + aRect.width);
+    result.height =
+        std::min<T>(y - result.y + height, aRect.y - result.y + aRect.height);
+    // See bug 1457110, this function expects to -only- size to 0,0 if the
+    // width/height is explicitly negative.
+    if (result.width < 0 || result.height < 0) {
+      result.SizeTo(0, 0);
+    }
+    return result;
+  }
+
+  // Gives the same results as Intersect() but handles integer overflow
+  // better. This comes at a tiny cost in performance.
+  // e.g. {INT_MIN, 0, 0, 20} Intersect { 5000, 0, 500, 20 } gives:
+  // {5000, 0, 0, 0}
+  [[nodiscard]] Sub SafeIntersect(const Sub& aRect) const {
+    Sub result;
+    result.x = std::max<T>(x, aRect.x);
+    result.y = std::max<T>(y, aRect.y);
+    T right = std::min<T>(x + width, aRect.x + aRect.width);
+    T bottom = std::min<T>(y + height, aRect.y + aRect.height);
+    // See bug 1457110, this function expects to -only- size to 0,0 if the
+    // width/height is explicitly negative.
+    if (right < result.x || bottom < result.y) {
+      result.width = 0;
+      result.height = 0;
+    } else {
+      result.width = right - result.x;
+      result.height = bottom - result.y;
+    }
+    return result;
+  }
+
+  // Sets *this to be the rectangle containing the intersection of the points
+  // (including edges) of *this and aRect. If there are no points in that
+  // intersection, sets *this to be an empty rectangle with x/y set to the
+  // std::max of the x/y of *this and aRect.
+  //
+  // 'this' can be the same object as either aRect1 or aRect2
+  bool IntersectRect(const Sub& aRect1, const Sub& aRect2) {
+    T newX = std::max<T>(aRect1.x, aRect2.x);
+    T newY = std::max<T>(aRect1.y, aRect2.y);
+    width = std::min<T>(aRect1.x - newX + aRect1.width,
+                        aRect2.x - newX + aRect2.width);
+    height = std::min<T>(aRect1.y - newY + aRect1.height,
+                         aRect2.y - newY + aRect2.height);
+    x = newX;
+    y = newY;
+    if (width <= 0 || height <= 0) {
+      SizeTo(0, 0);
+      return false;
+    }
+    return true;
+  }
+
+  // Returns the smallest rectangle that contains both the area of both
+  // this and aRect. Thus, empty input rectangles are ignored.
+  // Note: if both rectangles are empty, returns aRect.
+  // WARNING! This is not safe against overflow, prefer using SafeUnion instead
+  // when dealing with int-based rects.
+  [[nodiscard]] Sub Union(const Sub& aRect) const {
+    if (IsEmpty()) {
+      return aRect;
+    } else if (aRect.IsEmpty()) {
+      return *static_cast<const Sub*>(this);
+    } else {
+      return UnionEdges(aRect);
+    }
+  }
+  // Returns the smallest rectangle that contains both the points (including
+  // edges) of both aRect1 and aRect2.
+  // Thus, empty input rectangles are allowed to affect the result.
+  // WARNING! This is not safe against overflow, prefer using SafeUnionEdges
+  // instead when dealing with int-based rects.
+  [[nodiscard]] Sub UnionEdges(const Sub& aRect) const {
+    Sub result;
+    result.x = std::min(x, aRect.x);
+    result.y = std::min(y, aRect.y);
+    result.width = std::max(XMost(), aRect.XMost()) - result.x;
+    result.height = std::max(YMost(), aRect.YMost()) - result.y;
+    return result;
+  }
+  // Computes the smallest rectangle that contains both the area of both
+  // aRect1 and aRect2, and fills 'this' with the result.
+  // Thus, empty input rectangles are ignored.
+  // If both rectangles are empty, sets 'this' to aRect2.
+  //
+  // 'this' can be the same object as either aRect1 or aRect2
+  void UnionRect(const Sub& aRect1, const Sub& aRect2) {
+    *static_cast<Sub*>(this) = aRect1.Union(aRect2);
+  }
+
+  void OrWith(const Sub& aRect1) {
+    UnionRect(*static_cast<Sub*>(this), aRect1);
+  }
+
+  // Computes the smallest rectangle that contains both the points (including
+  // edges) of both aRect1 and aRect2.
+  // Thus, empty input rectangles are allowed to affect the result.
+  //
+  // 'this' can be the same object as either aRect1 or aRect2
+  void UnionRectEdges(const Sub& aRect1, const Sub& aRect2) {
+    *static_cast<Sub*>(this) = aRect1.UnionEdges(aRect2);
+  }
+
+  // Expands the rect to include the point
+  void ExpandToEnclose(const Point& aPoint) {
+    if (aPoint.x < x) {
+      width = XMost() - aPoint.x;
+      x = aPoint.x;
+    } else if (aPoint.x > XMost()) {
+      width = aPoint.x - x;
+    }
+    if (aPoint.y < y) {
+      height = YMost() - aPoint.y;
+      y = aPoint.y;
+    } else if (aPoint.y > YMost()) {
+      height = aPoint.y - y;
+    }
+  }
+
+  MOZ_ALWAYS_INLINE void SetRect(T aX, T aY, T aWidth, T aHeight) {
+    x = aX;
+    y = aY;
+    width = aWidth;
+    height = aHeight;
+  }
+  MOZ_ALWAYS_INLINE void SetRectX(T aX, T aWidth) {
+    x = aX;
+    width = aWidth;
+  }
+  MOZ_ALWAYS_INLINE void SetRectY(T aY, T aHeight) {
+    y = aY;
+    height = aHeight;
+  }
+  MOZ_ALWAYS_INLINE void SetBox(T aX, T aY, T aXMost, T aYMost) {
+    x = aX;
+    y = aY;
+    width = aXMost - aX;
+    height = aYMost - aY;
+  }
+  MOZ_ALWAYS_INLINE void SetNonEmptyBox(T aX, T aY, T aXMost, T aYMost) {
+    x = aX;
+    y = aY;
+    width = std::max(0, aXMost - aX);
+    height = std::max(0, aYMost - aY);
+  }
+  MOZ_ALWAYS_INLINE void SetBoxX(T aX, T aXMost) {
+    x = aX;
+    width = aXMost - aX;
+  }
+  MOZ_ALWAYS_INLINE void SetBoxY(T aY, T aYMost) {
+    y = aY;
+    height = aYMost - aY;
+  }
+  void SetRect(const Point& aPt, const SizeT& aSize) {
+    SetRect(aPt.x, aPt.y, aSize.width, aSize.height);
+  }
+  MOZ_ALWAYS_INLINE void GetRect(T* aX, T* aY, T* aWidth, T* aHeight) const {
+    *aX = x;
+    *aY = y;
+    *aWidth = width;
+    *aHeight = height;
+  }
+
+  MOZ_ALWAYS_INLINE void MoveTo(T aX, T aY) {
+    x = aX;
+    y = aY;
+  }
+  MOZ_ALWAYS_INLINE void MoveToX(T aX) { x = aX; }
+  MOZ_ALWAYS_INLINE void MoveToY(T aY) { y = aY; }
+  MOZ_ALWAYS_INLINE void MoveTo(const Point& aPoint) {
+    x = aPoint.x;
+    y = aPoint.y;
+  }
+  MOZ_ALWAYS_INLINE void MoveBy(T aDx, T aDy) {
+    x += aDx;
+    y += aDy;
+  }
+  MOZ_ALWAYS_INLINE void MoveByX(T aDx) { x += aDx; }
+  MOZ_ALWAYS_INLINE void MoveByY(T aDy) { y += aDy; }
+  MOZ_ALWAYS_INLINE void MoveBy(const Point& aPoint) {
+    x += aPoint.x;
+    y += aPoint.y;
+  }
+  MOZ_ALWAYS_INLINE void SizeTo(T aWidth, T aHeight) {
+    width = aWidth;
+    height = aHeight;
+  }
+  MOZ_ALWAYS_INLINE void SizeTo(const SizeT& aSize) {
+    width = aSize.width;
+    height = aSize.height;
+  }
+
+  // Variant of MoveBy that ensures that even after translation by a point that
+  // the rectangle coordinates will still fit within numeric limits. The origin
+  // and size will be clipped within numeric limits to ensure this.
+  void SafeMoveByX(T aDx) {
+    T x2 = XMost();
+    if (aDx >= T(0)) {
+      T limit = std::numeric_limits<T>::max();
+      x = limit - aDx < x ? limit : x + aDx;
+      width = (limit - aDx < x2 ? limit : x2 + aDx) - x;
+    } else {
+      T limit = std::numeric_limits<T>::min();
+      x = limit - aDx > x ? limit : x + aDx;
+      width = (limit - aDx > x2 ? limit : x2 + aDx) - x;
+    }
+  }
+  void SafeMoveByY(T aDy) {
+    T y2 = YMost();
+    if (aDy >= T(0)) {
+      T limit = std::numeric_limits<T>::max();
+      y = limit - aDy < y ? limit : y + aDy;
+      height = (limit - aDy < y2 ? limit : y2 + aDy) - y;
+    } else {
+      T limit = std::numeric_limits<T>::min();
+      y = limit - aDy > y ? limit : y + aDy;
+      height = (limit - aDy > y2 ? limit : y2 + aDy) - y;
+    }
+  }
+  void SafeMoveBy(T aDx, T aDy) {
+    SafeMoveByX(aDx);
+    SafeMoveByY(aDy);
+  }
+  void SafeMoveBy(const Point& aPoint) { SafeMoveBy(aPoint.x, aPoint.y); }
+
+  void Inflate(T aD) { Inflate(aD, aD); }
+  void Inflate(T aDx, T aDy) {
+    x -= aDx;
+    y -= aDy;
+    width += 2 * aDx;
+    height += 2 * aDy;
+  }
+  void Inflate(const MarginT& aMargin) {
+    x -= aMargin.left;
+    y -= aMargin.top;
+    width += aMargin.LeftRight();
+    height += aMargin.TopBottom();
+  }
+  void Inflate(const SizeT& aSize) { Inflate(aSize.width, aSize.height); }
+
+  void Deflate(T aD) { Deflate(aD, aD); }
+  void Deflate(T aDx, T aDy) {
+    x += aDx;
+    y += aDy;
+    width = std::max(T(0), width - 2 * aDx);
+    height = std::max(T(0), height - 2 * aDy);
+  }
+  void Deflate(const MarginT& aMargin) {
+    x += aMargin.left;
+    y += aMargin.top;
+    width = std::max(T(0), width - aMargin.LeftRight());
+    height = std::max(T(0), height - aMargin.TopBottom());
+  }
+  void Deflate(const SizeT& aSize) { Deflate(aSize.width, aSize.height); }
+
+  // Return true if the rectangles contain the same set of points, including
+  // points on the edges.
+  // Use when we care about the exact x/y/width/height values being
+  // equal (i.e. we care about differences in empty rectangles).
+  bool IsEqualEdges(const Sub& aRect) const {
+    return x == aRect.x && y == aRect.y && width == aRect.width &&
+           height == aRect.height;
+  }
+  MOZ_ALWAYS_INLINE bool IsEqualRect(T aX, T aY, T aW, T aH) {
+    return x == aX && y == aY && width == aW && height == aH;
+  }
+  MOZ_ALWAYS_INLINE bool IsEqualXY(T aX, T aY) { return x == aX && y == aY; }
+
+  MOZ_ALWAYS_INLINE bool IsEqualSize(T aW, T aH) {
+    return width == aW && height == aH;
+  }
+
+  // Return true if the rectangles contain the same area of the plane.
+  // Use when we do not care about differences in empty rectangles.
+  bool IsEqualInterior(const Sub& aRect) const {
+    return IsEqualEdges(aRect) || (IsEmpty() && aRect.IsEmpty());
+  }
+
+  friend Sub operator+(Sub aSub, const Point& aPoint) {
+    aSub += aPoint;
+    return aSub;
+  }
+  friend Sub operator-(Sub aSub, const Point& aPoint) {
+    aSub -= aPoint;
+    return aSub;
+  }
+  friend Sub operator+(Sub aSub, const SizeT& aSize) {
+    aSub += aSize;
+    return aSub;
+  }
+  friend Sub operator-(Sub aSub, const SizeT& aSize) {
+    aSub -= aSize;
+    return aSub;
+  }
+  Sub& operator+=(const Point& aPoint) {
+    MoveBy(aPoint);
+    return *static_cast<Sub*>(this);
+  }
+  Sub& operator-=(const Point& aPoint) {
+    MoveBy(-aPoint);
+    return *static_cast<Sub*>(this);
+  }
+  Sub& operator+=(const SizeT& aSize) {
+    width += aSize.width;
+    height += aSize.height;
+    return *static_cast<Sub*>(this);
+  }
+  Sub& operator-=(const SizeT& aSize) {
+    width -= aSize.width;
+    height -= aSize.height;
+    return *static_cast<Sub*>(this);
+  }
+  // Find difference as a Margin
+  MarginT operator-(const Sub& aRect) const {
+    return MarginT(aRect.y - y, XMost() - aRect.XMost(),
+                   YMost() - aRect.YMost(), aRect.x - x);
+  }
+
+  // Helpers for accessing the vertices
+  Point TopLeft() const { return Point(x, y); }
+  Point TopRight() const { return Point(XMost(), y); }
+  Point BottomLeft() const { return Point(x, YMost()); }
+  Point BottomRight() const { return Point(XMost(), YMost()); }
+  Point AtCorner(Corner aCorner) const {
+    switch (aCorner) {
+      case eCornerTopLeft:
+        return TopLeft();
+      case eCornerTopRight:
+        return TopRight();
+      case eCornerBottomRight:
+        return BottomRight();
+      case eCornerBottomLeft:
+        return BottomLeft();
+    }
+    MOZ_CRASH("GFX: Incomplete switch");
+  }
+  Point CCWCorner(mozilla::Side side) const {
+    switch (side) {
+      case eSideTop:
+        return TopLeft();
+      case eSideRight:
+        return TopRight();
+      case eSideBottom:
+        return BottomRight();
+      case eSideLeft:
+        return BottomLeft();
+    }
+    MOZ_CRASH("GFX: Incomplete switch");
+  }
+  Point CWCorner(mozilla::Side side) const {
+    switch (side) {
+      case eSideTop:
+        return TopRight();
+      case eSideRight:
+        return BottomRight();
+      case eSideBottom:
+        return BottomLeft();
+      case eSideLeft:
+        return TopLeft();
+    }
+    MOZ_CRASH("GFX: Incomplete switch");
+  }
+  Point Center() const { return Point(x, y) + Point(width, height) / 2; }
+  SizeT Size() const { return SizeT(width, height); }
+
+  T Area() const { return width * height; }
+
+  // Helper methods for computing the extents
+  MOZ_ALWAYS_INLINE T X() const { return x; }
+  MOZ_ALWAYS_INLINE T Y() const { return y; }
+  MOZ_ALWAYS_INLINE T Width() const { return width; }
+  MOZ_ALWAYS_INLINE T Height() const { return height; }
+  MOZ_ALWAYS_INLINE T XMost() const { return x + width; }
+  MOZ_ALWAYS_INLINE T YMost() const { return y + height; }
+
+  // Set width and height. SizeTo() sets them together.
+  MOZ_ALWAYS_INLINE void SetWidth(T aWidth) { width = aWidth; }
+  MOZ_ALWAYS_INLINE void SetHeight(T aHeight) { height = aHeight; }
+
+  // Get the coordinate of the edge on the given side.
+  T Edge(mozilla::Side aSide) const {
+    switch (aSide) {
+      case eSideTop:
+        return Y();
+      case eSideRight:
+        return XMost();
+      case eSideBottom:
+        return YMost();
+      case eSideLeft:
+        return X();
+    }
+    MOZ_CRASH("GFX: Incomplete switch");
+  }
+
+  // Moves one edge of the rect without moving the opposite edge.
+  void SetLeftEdge(T aX) {
+    width = XMost() - aX;
+    x = aX;
+  }
+  void SetRightEdge(T aXMost) { width = aXMost - x; }
+  void SetTopEdge(T aY) {
+    height = YMost() - aY;
+    y = aY;
+  }
+  void SetBottomEdge(T aYMost) { height = aYMost - y; }
+  void Swap() {
+    std::swap(x, y);
+    std::swap(width, height);
+  }
+
+  // Round the rectangle edges to integer coordinates, such that the rounded
+  // rectangle has the same set of pixel centers as the original rectangle.
+  // Edges at offset 0.5 round up.
+  // Suitable for most places where integral device coordinates
+  // are needed, but note that any translation should be applied first to
+  // avoid pixel rounding errors.
+  // Note that this is *not* rounding to nearest integer if the values are
+  // negative. They are always rounding as floor(n + 0.5). See
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14 If you need similar
+  // method which is using NS_round(), you should create new
+  // |RoundAwayFromZero()| method.
+  void Round() {
+    T x0 = static_cast<T>(std::floor(T(X()) + 0.5f));
+    T y0 = static_cast<T>(std::floor(T(Y()) + 0.5f));
+    T x1 = static_cast<T>(std::floor(T(XMost()) + 0.5f));
+    T y1 = static_cast<T>(std::floor(T(YMost()) + 0.5f));
+
+    x = x0;
+    y = y0;
+
+    width = x1 - x0;
+    height = y1 - y0;
+  }
+
+  // Snap the rectangle edges to integer coordinates, such that the
+  // original rectangle contains the resulting rectangle.
+  void RoundIn() {
+    T x0 = static_cast<T>(std::ceil(T(X())));
+    T y0 = static_cast<T>(std::ceil(T(Y())));
+    T x1 = static_cast<T>(std::floor(T(XMost())));
+    T y1 = static_cast<T>(std::floor(T(YMost())));
+
+    x = x0;
+    y = y0;
+
+    width = x1 - x0;
+    height = y1 - y0;
+  }
+
+  // Snap the rectangle edges to integer coordinates, such that the
+  // resulting rectangle contains the original rectangle.
+  void RoundOut() {
+    T x0 = static_cast<T>(std::floor(T(X())));
+    T y0 = static_cast<T>(std::floor(T(Y())));
+    T x1 = static_cast<T>(std::ceil(T(XMost())));
+    T y1 = static_cast<T>(std::ceil(T(YMost())));
+
+    x = x0;
+    y = y0;
+
+    width = x1 - x0;
+    height = y1 - y0;
+  }
+
+  // Scale 'this' by aScale.xScale and aScale.yScale without doing any rounding.
+  template <class Src, class Dst>
+  void Scale(const BaseScaleFactors2D<Src, Dst, T>& aScale) {
+    Scale(aScale.xScale, aScale.yScale);
+  }
+  // Scale 'this' by aScale without doing any rounding.
+  void Scale(T aScale) { Scale(aScale, aScale); }
+  // Scale 'this' by aXScale and aYScale, without doing any rounding.
+  void Scale(T aXScale, T aYScale) {
+    x = x * aXScale;
+    y = y * aYScale;
+    width = width * aXScale;
+    height = height * aYScale;
+  }
+  // Scale 'this' by aScale, converting coordinates to integers so that the
+  // result is the smallest integer-coordinate rectangle containing the
+  // unrounded result. Note: this can turn an empty rectangle into a non-empty
+  // rectangle
+  void ScaleRoundOut(double aScale) { ScaleRoundOut(aScale, aScale); }
+  // Scale 'this' by aXScale and aYScale, converting coordinates to integers so
+  // that the result is the smallest integer-coordinate rectangle containing the
+  // unrounded result.
+  // Note: this can turn an empty rectangle into a non-empty rectangle
+  void ScaleRoundOut(double aXScale, double aYScale) {
+    T right = static_cast<T>(ceil(double(XMost()) * aXScale));
+    T bottom = static_cast<T>(ceil(double(YMost()) * aYScale));
+    x = static_cast<T>(floor(double(x) * aXScale));
+    y = static_cast<T>(floor(double(y) * aYScale));
+    width = right - x;
+    height = bottom - y;
+  }
+  // Scale 'this' by aScale, converting coordinates to integers so that the
+  // result is the largest integer-coordinate rectangle contained by the
+  // unrounded result.
+  void ScaleRoundIn(double aScale) { ScaleRoundIn(aScale, aScale); }
+  // Scale 'this' by aXScale and aYScale, converting coordinates to integers so
+  // that the result is the largest integer-coordinate rectangle contained by
+  // the unrounded result.
+  void ScaleRoundIn(double aXScale, double aYScale) {
+    T right = static_cast<T>(floor(double(XMost()) * aXScale));
+    T bottom = static_cast<T>(floor(double(YMost()) * aYScale));
+    x = static_cast<T>(ceil(double(x) * aXScale));
+    y = static_cast<T>(ceil(double(y) * aYScale));
+    width = std::max<T>(0, right - x);
+    height = std::max<T>(0, bottom - y);
+  }
+  // Scale 'this' by 1/aScale, converting coordinates to integers so that the
+  // result is the smallest integer-coordinate rectangle containing the
+  // unrounded result. Note: this can turn an empty rectangle into a non-empty
+  // rectangle
+  void ScaleInverseRoundOut(double aScale) {
+    ScaleInverseRoundOut(aScale, aScale);
+  }
+  // Scale 'this' by 1/aXScale and 1/aYScale, converting coordinates to integers
+  // so that the result is the smallest integer-coordinate rectangle containing
+  // the unrounded result. Note: this can turn an empty rectangle into a
+  // non-empty rectangle
+  void ScaleInverseRoundOut(double aXScale, double aYScale) {
+    T right = static_cast<T>(ceil(double(XMost()) / aXScale));
+    T bottom = static_cast<T>(ceil(double(YMost()) / aYScale));
+    x = static_cast<T>(floor(double(x) / aXScale));
+    y = static_cast<T>(floor(double(y) / aYScale));
+    width = right - x;
+    height = bottom - y;
+  }
+  // Scale 'this' by 1/aScale, converting coordinates to integers so that the
+  // result is the largest integer-coordinate rectangle contained by the
+  // unrounded result.
+  void ScaleInverseRoundIn(double aScale) {
+    ScaleInverseRoundIn(aScale, aScale);
+  }
+  // Scale 'this' by 1/aXScale and 1/aYScale, converting coordinates to integers
+  // so that the result is the largest integer-coordinate rectangle contained by
+  // the unrounded result.
+  void ScaleInverseRoundIn(double aXScale, double aYScale) {
+    T right = static_cast<T>(floor(double(XMost()) / aXScale));
+    T bottom = static_cast<T>(floor(double(YMost()) / aYScale));
+    x = static_cast<T>(ceil(double(x) / aXScale));
+    y = static_cast<T>(ceil(double(y) / aYScale));
+    width = std::max<T>(0, right - x);
+    height = std::max<T>(0, bottom - y);
+  }
+
+  /**
+   * Clamp aPoint to this rectangle. It is allowed to end up on any
+   * edge of the rectangle.
+   */
+  [[nodiscard]] Point ClampPoint(const Point& aPoint) const {
+    using Coord = decltype(aPoint.x);
+    return Point(std::max(Coord(x), std::min(Coord(XMost()), aPoint.x)),
+                 std::max(Coord(y), std::min(Coord(YMost()), aPoint.y)));
+  }
+
+  /**
+   * Translate this rectangle to be inside aRect. If it doesn't fit inside
+   * aRect then the dimensions that don't fit will be shrunk so that they
+   * do fit. The resulting rect is returned.
+   */
+  [[nodiscard]] Sub MoveInsideAndClamp(const Sub& aRect) const {
+    Sub rect(std::max(aRect.x, x), std::max(aRect.y, y),
+             std::min(aRect.width, width), std::min(aRect.height, height));
+    rect.x = std::min(rect.XMost(), aRect.XMost()) - rect.width;
+    rect.y = std::min(rect.YMost(), aRect.YMost()) - rect.height;
+    return rect;
+  }
+
+  // Returns the largest rectangle that can be represented with 32-bit
+  // signed integers, centered around a point at 0,0.  As BaseRect's represent
+  // the dimensions as a top-left point with a width and height, the width
+  // and height will be the largest positive 32-bit value.  The top-left
+  // position coordinate is divided by two to center the rectangle around a
+  // point at 0,0.
+  static Sub MaxIntRect() {
+    return Sub(static_cast<T>(-std::numeric_limits<int32_t>::max() * 0.5),
+               static_cast<T>(-std::numeric_limits<int32_t>::max() * 0.5),
+               static_cast<T>(std::numeric_limits<int32_t>::max()),
+               static_cast<T>(std::numeric_limits<int32_t>::max()));
+  };
+
+  // Returns a point representing the distance, along each dimension, of the
+  // given point from this rectangle. The distance along a dimension is defined
+  // as zero if the point is within the bounds of the rectangle in that
+  // dimension; otherwise, it's the distance to the closer endpoint of the
+  // rectangle in that dimension.
+  Point DistanceTo(const Point& aPoint) const {
+    return {DistanceFromInterval(aPoint.x, x, XMost()),
+            DistanceFromInterval(aPoint.y, y, YMost())};
+  }
+
+  friend std::ostream& operator<<(
+      std::ostream& stream,
+      const BaseRect<T, Sub, Point, SizeT, MarginT>& aRect) {
+    return stream << "(x=" << aRect.x << ", y=" << aRect.y
+                  << ", w=" << aRect.width << ", h=" << aRect.height << ')';
+  }
+
+ private:
+  // Do not use the default operator== or operator!= !
+  // Use IsEqualEdges or IsEqualInterior explicitly.
+  bool operator==(const Sub& aRect) const { return false; }
+  bool operator!=(const Sub& aRect) const { return false; }
+
+  // Helper function for DistanceTo() that computes the distance of a
+  // coordinate along one dimension from an interval in that dimension.
+  static T DistanceFromInterval(T aCoord, T aIntervalStart, T aIntervalEnd) {
+    if (aCoord < aIntervalStart) {
+      return aIntervalStart - aCoord;
+    }
+    if (aCoord > aIntervalEnd) {
+      return aCoord - aIntervalEnd;
+    }
+    return 0;
+  }
+};
+
+}  // namespace mozilla::gfx
+
+#endif /* MOZILLA_GFX_BASERECT_H_ */