layout/generic/WritingModes.h
author Nika Layzell <nika@thelayzells.com>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 507828 5e6dae0c1e5a4939ccd406f14607f7fafffd45a7
parent 502673 35a90bca7f6326da82ceb3df210b0cf26139fa6a
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1448426 - Wrap windows.h to avoid problematic define statements, r=froydnj,glandium By default, windows.h exposes a large number of problematic define statements which are UpperCamelCase, such as a define from `CreateWindow` to `CreateWindow{A,W}`. As many of these names are generic (e.g. CreateFile, CreateWindow), they can mess up Gecko code that may legitimately have its own methods with the same names. The header also defines some traditional SCREAMING_SNAKE_CASE defines which can mess up our code by conflicting with local values. This patch adds a simple code generator which generates wrappers for these defines, and uses them to wrap the windows.h wrapper using the `stl_wrappers` mechanism, allowing us to use windows.h in more places. Differential Revision: https://phabricator.services.mozilla.com/D10932

/* -*- 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 WritingModes_h_
#define WritingModes_h_

#include "mozilla/ComputedStyle.h"
#include "mozilla/ComputedStyleInlines.h"

#include "nsRect.h"
#include "nsBidiUtils.h"

// It is the caller's responsibility to operate on logical-coordinate objects
// with matched writing modes. Failure to do so will be a runtime bug; the
// compiler can't catch it, but in debug mode, we'll throw an assertion.
// NOTE that in non-debug builds, a writing mode mismatch error will NOT be
// detected, yet the results will be nonsense (and may lead to further layout
// failures). Therefore, it is important to test (and fuzz-test) writing-mode
// support using debug builds.

// Methods in logical-coordinate classes that take another logical-coordinate
// object as a parameter should call CHECK_WRITING_MODE on it to verify that
// the writing modes match.
// (In some cases, there are internal (private) methods that don't do this;
// such methods should only be used by other methods that have already checked
// the writing modes.)
// The check ignores the eSidewaysMask bit of writing mode, because this does
// not affect the interpretation of logical coordinates.

#define CHECK_WRITING_MODE(param) \
   NS_ASSERTION(param.IgnoreSideways() == GetWritingMode().IgnoreSideways(), \
                "writing-mode mismatch")

namespace mozilla {

namespace widget {
struct IMENotification;
} // namespace widget

// Physical axis constants.
enum PhysicalAxis {
  eAxisVertical      = 0x0,
  eAxisHorizontal    = 0x1
};

inline LogicalAxis GetOrthogonalAxis(LogicalAxis aAxis)
{
  return aAxis == eLogicalAxisBlock ? eLogicalAxisInline : eLogicalAxisBlock;
}

inline bool IsInline(LogicalSide aSide) { return aSide & 0x2; }
inline bool IsBlock(LogicalSide aSide) { return !IsInline(aSide); }
inline bool IsEnd(LogicalSide aSide) { return aSide & 0x1; }
inline bool IsStart(LogicalSide aSide) { return !IsEnd(aSide); }

inline LogicalAxis GetAxis(LogicalSide aSide)
{
  return IsInline(aSide) ? eLogicalAxisInline : eLogicalAxisBlock;
}

inline LogicalEdge GetEdge(LogicalSide aSide)
{
  return IsEnd(aSide) ? eLogicalEdgeEnd : eLogicalEdgeStart;
}

inline LogicalEdge GetOppositeEdge(LogicalEdge aEdge)
{
  // This relies on the only two LogicalEdge enum values being 0 and 1.
  return LogicalEdge(1 - aEdge);
}

inline LogicalSide
MakeLogicalSide(LogicalAxis aAxis, LogicalEdge aEdge)
{
  return LogicalSide((aAxis << 1) | aEdge);
}

inline LogicalSide GetOppositeSide(LogicalSide aSide)
{
  return MakeLogicalSide(GetAxis(aSide), GetOppositeEdge(GetEdge(aSide)));
}

enum LogicalSideBits {
  eLogicalSideBitsNone   = 0,
  eLogicalSideBitsBStart = 1 << eLogicalSideBStart,
  eLogicalSideBitsBEnd   = 1 << eLogicalSideBEnd,
  eLogicalSideBitsIEnd   = 1 << eLogicalSideIEnd,
  eLogicalSideBitsIStart = 1 << eLogicalSideIStart,
  eLogicalSideBitsBBoth = eLogicalSideBitsBStart | eLogicalSideBitsBEnd,
  eLogicalSideBitsIBoth = eLogicalSideBitsIStart | eLogicalSideBitsIEnd,
  eLogicalSideBitsAll = eLogicalSideBitsBBoth | eLogicalSideBitsIBoth
};

enum LineRelativeDir {
  eLineRelativeDirOver  = eLogicalSideBStart,
  eLineRelativeDirUnder = eLogicalSideBEnd,
  eLineRelativeDirLeft  = eLogicalSideIStart,
  eLineRelativeDirRight = eLogicalSideIEnd
};

/**
 * LogicalSides represents a set of logical sides.
 */
struct LogicalSides final {
  LogicalSides() : mBits(0) {}
  explicit LogicalSides(LogicalSideBits aSideBits)
  {
    MOZ_ASSERT((aSideBits & ~eLogicalSideBitsAll) == 0, "illegal side bits");
    mBits = aSideBits;
  }
  bool IsEmpty() const { return mBits == 0; }
  bool BStart()  const { return mBits & eLogicalSideBitsBStart; }
  bool BEnd()    const { return mBits & eLogicalSideBitsBEnd; }
  bool IStart()  const { return mBits & eLogicalSideBitsIStart; }
  bool IEnd()    const { return mBits & eLogicalSideBitsIEnd; }
  bool Contains(LogicalSideBits aSideBits) const
  {
    MOZ_ASSERT((aSideBits & ~eLogicalSideBitsAll) == 0, "illegal side bits");
    return (mBits & aSideBits) == aSideBits;
  }
  LogicalSides operator|(LogicalSides aOther) const
  {
    return LogicalSides(LogicalSideBits(mBits | aOther.mBits));
  }
  LogicalSides operator|(LogicalSideBits aSideBits) const
  {
    return *this | LogicalSides(aSideBits);
  }
  LogicalSides& operator|=(LogicalSides aOther)
  {
    mBits |= aOther.mBits;
    return *this;
  }
  LogicalSides& operator|=(LogicalSideBits aSideBits)
  {
    return *this |= LogicalSides(aSideBits);
  }
  bool operator==(LogicalSides aOther) const
  {
    return mBits == aOther.mBits;
  }
  bool operator!=(LogicalSides aOther) const
  {
    return !(*this == aOther);
  }

private:
  uint8_t mBits;
};

/**
 * mozilla::WritingMode is an immutable class representing a
 * writing mode.
 *
 * It efficiently stores the writing mode and can rapidly compute
 * interesting things about it for use in layout.
 *
 * Writing modes are computed from the CSS 'direction',
 * 'writing-mode', and 'text-orientation' properties.
 * See CSS3 Writing Modes for more information
 *   http://www.w3.org/TR/css3-writing-modes/
 */
class WritingMode {
public:
  /**
   * Absolute inline flow direction
   */
  enum InlineDir {
    eInlineLTR = 0x00, // text flows horizontally left to right
    eInlineRTL = 0x02, // text flows horizontally right to left
    eInlineTTB = 0x01, // text flows vertically top to bottom
    eInlineBTT = 0x03, // text flows vertically bottom to top
  };

  /**
   * Absolute block flow direction
   */
  enum BlockDir {
    eBlockTB = 0x00, // horizontal lines stack top to bottom
    eBlockRL = 0x01, // vertical lines stack right to left
    eBlockLR = 0x05, // vertical lines stack left to right
  };

  /**
   * Line-relative (bidi-relative) inline flow direction
   */
  enum BidiDir {
    eBidiLTR = 0x00, // inline flow matches bidi LTR text
    eBidiRTL = 0x10, // inline flow matches bidi RTL text
  };

  /**
   * Unknown writing mode (should never actually be stored or used anywhere).
   */
  enum {
    eUnknownWritingMode = 0xff
  };

  /**
   * Return the absolute inline flow direction as an InlineDir
   */
  InlineDir GetInlineDir() const { return InlineDir(mWritingMode & eInlineMask); }

  /**
   * Return the absolute block flow direction as a BlockDir
   */
  BlockDir GetBlockDir() const { return BlockDir(mWritingMode & eBlockMask); }

  /**
   * Return the line-relative inline flow direction as a BidiDir
   */
  BidiDir GetBidiDir() const { return BidiDir(mWritingMode & eBidiMask); }

  /**
   * Return true if the inline flow direction is against physical direction
   * (i.e. right-to-left or bottom-to-top).
   * This occurs when writing-mode is sideways-lr OR direction is rtl (but not
   * if both of those are true).
   */
  bool IsInlineReversed() const { return !!(mWritingMode & eInlineFlowMask); }

  /**
   * Return true if bidi direction is LTR. (Convenience method)
   */
  bool IsBidiLTR() const { return eBidiLTR == GetBidiDir(); }

  /**
   * True if vertical-mode block direction is LR (convenience method).
   */
  bool IsVerticalLR() const { return eBlockLR == GetBlockDir(); }

  /**
   * True if vertical-mode block direction is RL (convenience method).
   */
  bool IsVerticalRL() const { return eBlockRL == GetBlockDir(); }

  /**
   * True if vertical writing mode, i.e. when
   * writing-mode: vertical-lr | vertical-rl.
   */
  bool IsVertical() const { return !!(mWritingMode & eOrientationMask); }

  /**
   * True if line-over/line-under are inverted from block-start/block-end.
   * This is true only when writing-mode is vertical-lr.
   */
  bool IsLineInverted() const { return !!(mWritingMode & eLineOrientMask); }

  /**
   * Block-axis flow-relative to line-relative factor.
   * May be used as a multiplication factor for block-axis coordinates
   * to convert between flow- and line-relative coordinate systems (e.g.
   * positioning an over- or under-line decoration).
   */
  int FlowRelativeToLineRelativeFactor() const
  {
    return IsLineInverted() ? -1 : 1;
  }

  /**
   * True if the text-orientation will force all text to be rendered sideways
   * in vertical lines, in which case we should prefer an alphabetic baseline;
   * otherwise, the default is centered.
   * Note that some glyph runs may be rendered sideways even if this is false,
   * due to text-orientation:mixed resolution, but in that case the dominant
   * baseline remains centered.
   */
  bool IsSideways() const { return !!(mWritingMode & eSidewaysMask); }

#ifdef DEBUG // Used by CHECK_WRITING_MODE to compare modes without regard
             // for the eSidewaysMask flag.
  WritingMode IgnoreSideways() const {
    return WritingMode(mWritingMode & ~eSidewaysMask);
  }
#endif

  /**
   * Return true if boxes with this writing mode should use central baselines.
   */
  bool IsCentralBaseline() const { return IsVertical() && !IsSideways(); }

  /**
   * Return true if boxes with this writing mode should use alphabetical
   * baselines.
   */
  bool IsAlphabeticalBaseline() const { return !IsCentralBaseline(); }


  static mozilla::PhysicalAxis PhysicalAxisForLogicalAxis(
                                              uint8_t aWritingModeValue,
                                              LogicalAxis aAxis)
  {
    // This relies on bit 0 of a writing-value mode indicating vertical
    // orientation and bit 0 of a LogicalAxis value indicating the inline axis,
    // so that it can correctly form mozilla::PhysicalAxis values using bit
    // manipulation.
    static_assert(NS_STYLE_WRITING_MODE_HORIZONTAL_TB == 0 &&
                  NS_STYLE_WRITING_MODE_VERTICAL_RL == 1 &&
                  NS_STYLE_WRITING_MODE_VERTICAL_LR == 3 &&
                  eLogicalAxisBlock == 0 &&
                  eLogicalAxisInline == 1 &&
                  eAxisVertical == 0 &&
                  eAxisHorizontal == 1,
                  "unexpected writing-mode, logical axis or physical axis "
                  "constant values");
    return mozilla::PhysicalAxis((aWritingModeValue ^ aAxis) & 0x1);
  }

  mozilla::PhysicalAxis PhysicalAxis(LogicalAxis aAxis) const
  {
    // This will set wm to either NS_STYLE_WRITING_MODE_HORIZONTAL_TB or
    // NS_STYLE_WRITING_MODE_VERTICAL_RL, and not the other two (real
    // and hypothetical) values.  But this is fine; we only need to
    // distinguish between vertical and horizontal in
    // PhysicalAxisForLogicalAxis.
    int wm = mWritingMode & eOrientationMask;
    return PhysicalAxisForLogicalAxis(wm, aAxis);
  }

  static mozilla::Side PhysicalSideForBlockAxis(uint8_t aWritingModeValue,
                                                LogicalEdge aEdge)
  {
    // indexes are NS_STYLE_WRITING_MODE_* values, which are the same as these
    // two-bit values:
    //   bit 0 = the eOrientationMask value
    //   bit 1 = the eBlockFlowMask value
    static const mozilla::Side kLogicalBlockSides[][2] = {
      { eSideTop,    eSideBottom },  // horizontal-tb
      { eSideRight,  eSideLeft   },  // vertical-rl
      { eSideBottom, eSideTop    },  // (horizontal-bt)
      { eSideLeft,   eSideRight  },  // vertical-lr
    };

    // Ignore the SIDEWAYS_MASK bit of the writing-mode value, as this has no
    // effect on the side mappings.
    aWritingModeValue &= ~NS_STYLE_WRITING_MODE_SIDEWAYS_MASK;

    // What's left of the writing-mode should be in the range 0-3:
    NS_ASSERTION(aWritingModeValue < 4, "invalid aWritingModeValue value");

    return kLogicalBlockSides[aWritingModeValue][aEdge];
  }

  mozilla::Side PhysicalSideForInlineAxis(LogicalEdge aEdge) const
  {
    // indexes are four-bit values:
    //   bit 0 = the eOrientationMask value
    //   bit 1 = the eInlineFlowMask value
    //   bit 2 = the eBlockFlowMask value
    //   bit 3 = the eLineOrientMask value
    // Not all of these combinations can actually be specified via CSS: there
    // is no horizontal-bt writing-mode, and no text-orientation value that
    // produces "inverted" text. (The former 'sideways-left' value, no longer
    // in the spec, would have produced this in vertical-rl mode.)
    static const mozilla::Side kLogicalInlineSides[][2] = {
      { eSideLeft,   eSideRight  },  // horizontal-tb               ltr
      { eSideTop,    eSideBottom },  // vertical-rl                 ltr
      { eSideRight,  eSideLeft   },  // horizontal-tb               rtl
      { eSideBottom, eSideTop    },  // vertical-rl                 rtl
      { eSideRight,  eSideLeft   },  // (horizontal-bt)  (inverted) ltr
      { eSideTop,    eSideBottom },  // sideways-lr                 rtl
      { eSideLeft,   eSideRight  },  // (horizontal-bt)  (inverted) rtl
      { eSideBottom, eSideTop    },  // sideways-lr                 ltr
      { eSideLeft,   eSideRight  },  // horizontal-tb    (inverted) rtl
      { eSideTop,    eSideBottom },  // vertical-rl      (inverted) rtl
      { eSideRight,  eSideLeft   },  // horizontal-tb    (inverted) ltr
      { eSideBottom, eSideTop    },  // vertical-rl      (inverted) ltr
      { eSideLeft,   eSideRight  },  // (horizontal-bt)             ltr
      { eSideTop,    eSideBottom },  // vertical-lr                 ltr
      { eSideRight,  eSideLeft   },  // (horizontal-bt)             rtl
      { eSideBottom, eSideTop    },  // vertical-lr                 rtl
    };

    // Inline axis sides depend on all three of writing-mode, text-orientation
    // and direction, which are encoded in the eOrientationMask,
    // eInlineFlowMask, eBlockFlowMask and eLineOrientMask bits.  Use these four
    // bits to index into kLogicalInlineSides.
    static_assert(eOrientationMask == 0x01 && eInlineFlowMask == 0x02 &&
                  eBlockFlowMask == 0x04 && eLineOrientMask == 0x08,
                  "unexpected mask values");
    int index = mWritingMode & 0x0F;
    return kLogicalInlineSides[index][aEdge];
  }

  /**
   * Returns the physical side corresponding to the specified logical side,
   * given the current writing mode.
   */
  mozilla::Side PhysicalSide(LogicalSide aSide) const
  {
    if (IsBlock(aSide)) {
      static_assert(eOrientationMask == 0x01 && eBlockFlowMask == 0x04,
                    "unexpected mask values");
      int wm = ((mWritingMode & eBlockFlowMask) >> 1) |
               (mWritingMode & eOrientationMask);
      return PhysicalSideForBlockAxis(wm, GetEdge(aSide));
    }

    return PhysicalSideForInlineAxis(GetEdge(aSide));
  }

  /**
   * Returns the logical side corresponding to the specified physical side,
   * given the current writing mode.
   * (This is the inverse of the PhysicalSide() method above.)
   */
  LogicalSide LogicalSideForPhysicalSide(mozilla::Side aSide) const
  {
    // indexes are four-bit values:
    //   bit 0 = the eOrientationMask value
    //   bit 1 = the eInlineFlowMask value
    //   bit 2 = the eBlockFlowMask value
    //   bit 3 = the eLineOrientMask value
    static const LogicalSide kPhysicalToLogicalSides[][4] = {
      // top                right
      // bottom             left
      { eLogicalSideBStart, eLogicalSideIEnd,
        eLogicalSideBEnd,   eLogicalSideIStart },  // horizontal-tb         ltr
      { eLogicalSideIStart, eLogicalSideBStart,
        eLogicalSideIEnd,   eLogicalSideBEnd   },  // vertical-rl           ltr
      { eLogicalSideBStart, eLogicalSideIStart,
        eLogicalSideBEnd,   eLogicalSideIEnd   },  // horizontal-tb         rtl
      { eLogicalSideIEnd,   eLogicalSideBStart,
        eLogicalSideIStart, eLogicalSideBEnd   },  // vertical-rl           rtl
      { eLogicalSideBEnd,   eLogicalSideIStart,
        eLogicalSideBStart, eLogicalSideIEnd   },  // (horizontal-bt) (inv) ltr
      { eLogicalSideIStart, eLogicalSideBEnd,
        eLogicalSideIEnd,   eLogicalSideBStart },  // vertical-lr   sw-left rtl
      { eLogicalSideBEnd,   eLogicalSideIEnd,
        eLogicalSideBStart, eLogicalSideIStart },  // (horizontal-bt) (inv) rtl
      { eLogicalSideIEnd,   eLogicalSideBEnd,
        eLogicalSideIStart, eLogicalSideBStart },  // vertical-lr   sw-left ltr
      { eLogicalSideBStart, eLogicalSideIEnd,
        eLogicalSideBEnd,   eLogicalSideIStart },  // horizontal-tb   (inv) rtl
      { eLogicalSideIStart, eLogicalSideBStart,
        eLogicalSideIEnd,   eLogicalSideBEnd   },  // vertical-rl   sw-left rtl
      { eLogicalSideBStart, eLogicalSideIStart,
        eLogicalSideBEnd,   eLogicalSideIEnd   },  // horizontal-tb   (inv) ltr
      { eLogicalSideIEnd,   eLogicalSideBStart,
        eLogicalSideIStart, eLogicalSideBEnd   },  // vertical-rl   sw-left ltr
      { eLogicalSideBEnd,   eLogicalSideIEnd,
        eLogicalSideBStart, eLogicalSideIStart },  // (horizontal-bt)       ltr
      { eLogicalSideIStart, eLogicalSideBEnd,
        eLogicalSideIEnd,   eLogicalSideBStart },  // vertical-lr           ltr
      { eLogicalSideBEnd,   eLogicalSideIStart,
        eLogicalSideBStart, eLogicalSideIEnd   },  // (horizontal-bt)       rtl
      { eLogicalSideIEnd,   eLogicalSideBEnd,
        eLogicalSideIStart, eLogicalSideBStart },  // vertical-lr           rtl
    };

    static_assert(eOrientationMask == 0x01 && eInlineFlowMask == 0x02 &&
                  eBlockFlowMask == 0x04 && eLineOrientMask == 0x08,
                  "unexpected mask values");
    int index = mWritingMode & 0x0F;
    return kPhysicalToLogicalSides[index][aSide];
  }

  /**
   * Returns the logical side corresponding to the specified
   * line-relative direction, given the current writing mode.
   */
  LogicalSide LogicalSideForLineRelativeDir(LineRelativeDir aDir) const
  {
    auto side = static_cast<LogicalSide>(aDir);
    if (IsInline(side)) {
      return IsBidiLTR() ? side : GetOppositeSide(side);
    }
    return !IsLineInverted() ? side : GetOppositeSide(side);
  }

  /**
   * Default constructor gives us a horizontal, LTR writing mode.
   * XXX We will probably eliminate this and require explicit initialization
   *     in all cases once transition is complete.
   */
  WritingMode()
    : mWritingMode(0)
  { }

  /**
   * Construct writing mode based on a ComputedStyle.
   */
  explicit WritingMode(ComputedStyle* aComputedStyle)
  {
    NS_ASSERTION(aComputedStyle, "we need an ComputedStyle here");
    InitFromStyleVisibility(aComputedStyle->StyleVisibility());
  }

  explicit WritingMode(const nsStyleVisibility* aStyleVisibility)
  {
    NS_ASSERTION(aStyleVisibility, "we need an nsStyleVisibility here");
    InitFromStyleVisibility(aStyleVisibility);
  }

private:
  void InitFromStyleVisibility(const nsStyleVisibility* aStyleVisibility)
  {
    switch (aStyleVisibility->mWritingMode) {
      case NS_STYLE_WRITING_MODE_HORIZONTAL_TB:
        mWritingMode = 0;
        break;

      case NS_STYLE_WRITING_MODE_VERTICAL_LR:
      {
        mWritingMode = eBlockFlowMask |
                       eLineOrientMask |
                       eOrientationMask;
        uint8_t textOrientation = aStyleVisibility->mTextOrientation;
        if (textOrientation == NS_STYLE_TEXT_ORIENTATION_SIDEWAYS) {
          mWritingMode |= eSidewaysMask;
        }
        break;
      }

      case NS_STYLE_WRITING_MODE_VERTICAL_RL:
      {
        mWritingMode = eOrientationMask;
        uint8_t textOrientation = aStyleVisibility->mTextOrientation;
        if (textOrientation == NS_STYLE_TEXT_ORIENTATION_SIDEWAYS) {
          mWritingMode |= eSidewaysMask;
        }
        break;
      }

      case NS_STYLE_WRITING_MODE_SIDEWAYS_LR:
        mWritingMode = eBlockFlowMask |
                       eInlineFlowMask |
                       eOrientationMask |
                       eSidewaysMask;
        break;

      case NS_STYLE_WRITING_MODE_SIDEWAYS_RL:
        mWritingMode = eOrientationMask |
                       eSidewaysMask;
        break;

      default:
        MOZ_ASSERT_UNREACHABLE("unknown writing mode!");
        mWritingMode = 0;
        break;
    }

    if (NS_STYLE_DIRECTION_RTL == aStyleVisibility->mDirection) {
      mWritingMode ^= eInlineFlowMask | eBidiMask;
    }
  }
public:

  /**
   * This function performs fixup for elements with 'unicode-bidi: plaintext',
   * where inline directionality is derived from the Unicode bidi categories
   * of the element's content, and not the CSS 'direction' property.
   *
   * The WritingMode constructor will have already incorporated the 'direction'
   * property into our flag bits, so such elements need to use this method
   * (after resolving the bidi level of their content) to update the direction
   * bits as needed.
   *
   * If it turns out that our bidi direction already matches what plaintext
   * resolution determined, there's nothing to do here. If it didn't (i.e. if
   * the rtl-ness doesn't match), then we correct the direction by flipping the
   * same bits that get flipped in the constructor's CSS 'direction'-based
   * chunk.
   *
   * XXX change uint8_t to UBiDiLevel after bug 924851
   */
  void SetDirectionFromBidiLevel(uint8_t level)
  {
    if (IS_LEVEL_RTL(level) == IsBidiLTR()) {
      mWritingMode ^= eBidiMask | eInlineFlowMask;
    }
  }

  /**
   * Compare two WritingModes for equality.
   */
  bool operator==(const WritingMode& aOther) const
  {
    return mWritingMode == aOther.mWritingMode;
  }

  bool operator!=(const WritingMode& aOther) const
  {
    return mWritingMode != aOther.mWritingMode;
  }

  /**
   * Check whether two modes are orthogonal to each other.
   */
  bool IsOrthogonalTo(const WritingMode& aOther) const
  {
    return IsVertical() != aOther.IsVertical();
  }

  /**
   * Returns true if this WritingMode's aLogicalAxis has the same physical
   * start side as the parallel axis of WritingMode |aOther|.
   *
   * @param aLogicalAxis The axis to compare from this WritingMode.
   * @param aOther The other WritingMode (from which we'll choose the axis
   *               that's parallel to this WritingMode's aLogicalAxis, for
   *               comparison).
   */
  bool ParallelAxisStartsOnSameSide(LogicalAxis aLogicalAxis,
                                    const WritingMode& aOther) const
  {
    mozilla::Side myStartSide =
      this->PhysicalSide(MakeLogicalSide(aLogicalAxis,
                                         eLogicalEdgeStart));

    // Figure out which of aOther's axes is parallel to |this| WritingMode's
    // aLogicalAxis, and get its physical start side as well.
    LogicalAxis otherWMAxis = aOther.IsOrthogonalTo(*this) ?
      GetOrthogonalAxis(aLogicalAxis) : aLogicalAxis;
    mozilla::Side otherWMStartSide =
      aOther.PhysicalSide(MakeLogicalSide(otherWMAxis,
                                          eLogicalEdgeStart));

    NS_ASSERTION(myStartSide % 2 == otherWMStartSide % 2,
                 "Should end up with sides in the same physical axis");
    return myStartSide == otherWMStartSide;
  }

  uint8_t GetBits() const { return mWritingMode; }

  const char* DebugString() const {
    return IsVertical()
      ? IsVerticalLR()
        ? IsBidiLTR()
          ? IsSideways() ? "sw-lr-ltr" : "v-lr-ltr"
          : IsSideways() ? "sw-lr-rtl" : "v-lr-rtl"
        : IsBidiLTR()
          ? IsSideways() ? "sw-rl-ltr" : "v-rl-ltr"
          : IsSideways() ? "sw-rl-rtl" : "v-rl-rtl"
      : IsBidiLTR() ? "h-ltr" : "h-rtl"
      ;
  }

private:
  friend class LogicalPoint;
  friend class LogicalSize;
  friend class LogicalMargin;
  friend class LogicalRect;

  friend struct IPC::ParamTraits<WritingMode>;
  // IMENotification cannot store this class directly since this has some
  // constructors.  Therefore, it stores mWritingMode and recreate the
  // instance from it.
  friend struct widget::IMENotification;

  /**
   * Return a WritingMode representing an unknown value.
   */
  static inline WritingMode Unknown()
  {
    return WritingMode(eUnknownWritingMode);
  }

  /**
   * Constructing a WritingMode with an arbitrary value is a private operation
   * currently only used by the Unknown() static method.
   */
  explicit WritingMode(uint8_t aValue)
    : mWritingMode(aValue)
  { }

  uint8_t mWritingMode;

  enum Masks {
    // Masks for our bits; true chosen as opposite of commonest case
    eOrientationMask = 0x01, // true means vertical text
    eInlineFlowMask  = 0x02, // true means absolute RTL/BTT (against physical coords)
    eBlockFlowMask   = 0x04, // true means vertical-LR (or horizontal-BT if added)
    eLineOrientMask  = 0x08, // true means over != block-start
    eBidiMask        = 0x10, // true means line-relative RTL (bidi RTL)
    // Note: We have one excess bit of info; WritingMode can pack into 4 bits.
    // But since we have space, we're caching interesting things for fast access.

    eSidewaysMask    = 0x20, // true means text is being rendered vertically
                             // using rotated glyphs (i.e. writing-mode is
                             // sideways-*, or writing-mode is vertical-* AND
                             // text-orientation is sideways),
                             // which means we'll use alphabetic instead of
                             // centered default baseline for vertical text

    // Masks for output enums
    eInlineMask = 0x03,
    eBlockMask  = 0x05
  };
};


/**
 * Logical-coordinate classes:
 *
 * There are three sets of coordinate space:
 *   - physical (top, left, bottom, right)
 *       relative to graphics coord system
 *   - flow-relative (block-start, inline-start, block-end, inline-end)
 *       relative to block/inline flow directions
 *   - line-relative (line-over, line-left, line-under, line-right)
 *       relative to glyph orientation / inline bidi directions
 * See CSS3 Writing Modes for more information
 *   http://www.w3.org/TR/css3-writing-modes/#abstract-box
 *
 * For shorthand, B represents the block-axis
 *                I represents the inline-axis
 *
 * The flow-relative geometric classes store coords in flow-relative space.
 * They use a private ns{Point,Size,Rect,Margin} member to store the actual
 * coordinate values, but reinterpret them as logical instead of physical.
 * This allows us to easily perform calculations in logical space (provided
 * writing modes of the operands match), by simply mapping to nsPoint (etc)
 * methods.
 *
 * Physical-coordinate accessors/setters are responsible to translate these
 * internal logical values as necessary.
 *
 * In DEBUG builds, the logical types store their WritingMode and check
 * that the same WritingMode is passed whenever callers ask them to do a
 * writing-mode-dependent operation. Non-DEBUG builds do NOT check this,
 * to avoid the overhead of storing WritingMode fields.
 *
 * Open question: do we need a different set optimized for line-relative
 * math, for use in nsLineLayout and the like? Or is multiplying values
 * by FlowRelativeToLineRelativeFactor() enough?
 */

/**
 * Flow-relative point
 */
class LogicalPoint {
public:
  explicit LogicalPoint(WritingMode aWritingMode)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mPoint(0, 0)
  { }

  // Construct from a writing mode and individual coordinates (which MUST be
  // values in that writing mode, NOT physical coordinates!)
  LogicalPoint(WritingMode aWritingMode, nscoord aI, nscoord aB)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mPoint(aI, aB)
  { }

  // Construct from a writing mode and a physical point, within a given
  // containing rectangle's size (defining the conversion between LTR
  // and RTL coordinates, and between TTB and BTT coordinates).
  LogicalPoint(WritingMode aWritingMode,
               const nsPoint& aPoint,
               const nsSize& aContainerSize)
#ifdef DEBUG
    : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      I() = aWritingMode.IsInlineReversed() ? aContainerSize.height - aPoint.y
                                            : aPoint.y;
      B() = aWritingMode.IsVerticalLR() ? aPoint.x
                                        : aContainerSize.width - aPoint.x;
    } else {
      I() = aWritingMode.IsInlineReversed() ? aContainerSize.width - aPoint.x
                                            : aPoint.x;
      B() = aPoint.y;
    }
  }

  /**
   * Read-only (const) access to the logical coordinates.
   */
  nscoord I(WritingMode aWritingMode) const // inline-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.x;
  }
  nscoord B(WritingMode aWritingMode) const // block-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.y;
  }
  nscoord LineRelative(WritingMode aWritingMode,
                       const nsSize& aContainerSize) const // line-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return I();
    }
    return (aWritingMode.IsVertical() ? aContainerSize.height
                                      : aContainerSize.width) - I();
  }

  /**
   * These non-const accessors return a reference (lvalue) that can be
   * assigned to by callers.
   */
  nscoord& I(WritingMode aWritingMode) // inline-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.x;
  }
  nscoord& B(WritingMode aWritingMode) // block-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.y;
  }

  /**
   * Return a physical point corresponding to our logical coordinates,
   * converted according to our writing mode.
   */
  nsPoint GetPhysicalPoint(WritingMode aWritingMode,
                           const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return nsPoint(aWritingMode.IsVerticalLR()
                     ? B() : aContainerSize.width - B(),
                     aWritingMode.IsInlineReversed()
                     ? aContainerSize.height - I() : I());
    } else {
      return nsPoint(aWritingMode.IsInlineReversed()
                     ? aContainerSize.width - I() : I(),
                     B());
    }
  }

  /**
   * Return the equivalent point in a different writing mode.
   */
  LogicalPoint ConvertTo(WritingMode aToMode, WritingMode aFromMode,
                         const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode ?
      *this : LogicalPoint(aToMode,
                           GetPhysicalPoint(aFromMode, aContainerSize),
                           aContainerSize);
  }

  bool operator==(const LogicalPoint& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mPoint == aOther.mPoint;
  }

  bool operator!=(const LogicalPoint& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mPoint != aOther.mPoint;
  }

  LogicalPoint operator+(const LogicalPoint& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    // In non-debug builds, LogicalPoint does not store the WritingMode,
    // so the first parameter here (which will always be eUnknownWritingMode)
    // is ignored.
    return LogicalPoint(GetWritingMode(),
                        mPoint.x + aOther.mPoint.x,
                        mPoint.y + aOther.mPoint.y);
  }

  LogicalPoint& operator+=(const LogicalPoint& aOther)
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    I() += aOther.I();
    B() += aOther.B();
    return *this;
  }

  LogicalPoint operator-(const LogicalPoint& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    // In non-debug builds, LogicalPoint does not store the WritingMode,
    // so the first parameter here (which will always be eUnknownWritingMode)
    // is ignored.
    return LogicalPoint(GetWritingMode(),
                        mPoint.x - aOther.mPoint.x,
                        mPoint.y - aOther.mPoint.y);
  }

  LogicalPoint& operator-=(const LogicalPoint& aOther)
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    I() -= aOther.I();
    B() -= aOther.B();
    return *this;
  }

private:
  friend class LogicalRect;

  /**
   * NOTE that in non-DEBUG builds, GetWritingMode() always returns
   * eUnknownWritingMode, as the current mode is not stored in the logical-
   * geometry classes. Therefore, this method is private; it is used ONLY
   * by the DEBUG-mode checking macros in this class and its friends;
   * other code is not allowed to ask a logical point for its writing mode,
   * as this info will simply not be available in non-DEBUG builds.
   *
   * Also, in non-DEBUG builds, CHECK_WRITING_MODE does nothing, and the
   * WritingMode parameter to logical methods will generally be optimized
   * away altogether.
   */
#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  // We don't allow construction of a LogicalPoint with no writing mode.
  LogicalPoint() = delete;

  // Accessors that don't take or check a WritingMode value.
  // These are for internal use only; they are called by methods that have
  // themselves already checked the WritingMode passed by the caller.
  nscoord I() const // inline-axis
  {
    return mPoint.x;
  }
  nscoord B() const // block-axis
  {
    return mPoint.y;
  }

  nscoord& I() // inline-axis
  {
    return mPoint.x;
  }
  nscoord& B() // block-axis
  {
    return mPoint.y;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif

  // We use an nsPoint to hold the coordinates, but reinterpret its .x and .y
  // fields as the inline and block directions. Hence, this is not exposed
  // directly, but only through accessors that will map them according to the
  // writing mode.
  nsPoint mPoint;
};

/**
 * Flow-relative size
 */
class LogicalSize {
public:
  explicit LogicalSize(WritingMode aWritingMode)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mSize(0, 0)
  { }

  LogicalSize(WritingMode aWritingMode, nscoord aISize, nscoord aBSize)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mSize(aISize, aBSize)
  { }

  LogicalSize(WritingMode aWritingMode, const nsSize& aPhysicalSize)
#ifdef DEBUG
    : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      ISize() = aPhysicalSize.height;
      BSize() = aPhysicalSize.width;
    } else {
      ISize() = aPhysicalSize.width;
      BSize() = aPhysicalSize.height;
    }
  }

  void SizeTo(WritingMode aWritingMode, nscoord aISize, nscoord aBSize)
  {
    CHECK_WRITING_MODE(aWritingMode);
    mSize.SizeTo(aISize, aBSize);
  }

  /**
   * Dimensions in logical and physical terms
   */
  nscoord ISize(WritingMode aWritingMode) const // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.width;
  }
  nscoord BSize(WritingMode aWritingMode) const // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.height;
  }
  nscoord Size(LogicalAxis aAxis, WritingMode aWM) const
  {
    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
  }

  nscoord Width(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? BSize() : ISize();
  }
  nscoord Height(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? ISize() : BSize();
  }

  /**
   * Writable references to the logical dimensions
   */
  nscoord& ISize(WritingMode aWritingMode) // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.width;
  }
  nscoord& BSize(WritingMode aWritingMode) // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.height;
  }
  nscoord& Size(LogicalAxis aAxis, WritingMode aWM)
  {
    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
  }

  /**
   * Return an nsSize containing our physical dimensions
   */
  nsSize GetPhysicalSize(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ?
      nsSize(BSize(), ISize()) : nsSize(ISize(), BSize());
  }

  /**
   * Return a LogicalSize representing this size in a different writing mode
   */
  LogicalSize ConvertTo(WritingMode aToMode, WritingMode aFromMode) const
  {
#ifdef DEBUG
    // In DEBUG builds make sure to return a LogicalSize with the
    // expected writing mode
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode ?
      *this : LogicalSize(aToMode, GetPhysicalSize(aFromMode));
#else
    // optimization for non-DEBUG builds where LogicalSize doesn't store
    // the writing mode
    return (aToMode == aFromMode || !aToMode.IsOrthogonalTo(aFromMode))
           ? *this : LogicalSize(aToMode, BSize(), ISize());
#endif
  }

  /**
   * Test if a size is (0, 0).
   */
  bool IsAllZero() const
  {
    return ISize() == 0 && BSize() == 0;
  }

  /**
   * Various binary operators on LogicalSize. These are valid ONLY for operands
   * that share the same writing mode.
   */
  bool operator==(const LogicalSize& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mSize == aOther.mSize;
  }

  bool operator!=(const LogicalSize& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mSize != aOther.mSize;
  }

  LogicalSize operator+(const LogicalSize& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return LogicalSize(GetWritingMode(), ISize() + aOther.ISize(),
                                         BSize() + aOther.BSize());
  }
  LogicalSize& operator+=(const LogicalSize& aOther)
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    ISize() += aOther.ISize();
    BSize() += aOther.BSize();
    return *this;
  }

  LogicalSize operator-(const LogicalSize& aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return LogicalSize(GetWritingMode(), ISize() - aOther.ISize(),
                                         BSize() - aOther.BSize());
  }
  LogicalSize& operator-=(const LogicalSize& aOther)
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    ISize() -= aOther.ISize();
    BSize() -= aOther.BSize();
    return *this;
  }

private:
  friend class LogicalRect;

  LogicalSize() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord ISize() const // inline-size
  {
    return mSize.width;
  }
  nscoord BSize() const // block-size
  {
    return mSize.height;
  }

  nscoord& ISize() // inline-size
  {
    return mSize.width;
  }
  nscoord& BSize() // block-size
  {
    return mSize.height;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  nsSize      mSize;
};

/**
 * Flow-relative margin
 */
class LogicalMargin {
public:
  explicit LogicalMargin(WritingMode aWritingMode)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mMargin(0, 0, 0, 0)
  { }

  LogicalMargin(WritingMode aWritingMode,
                nscoord aBStart, nscoord aIEnd,
                nscoord aBEnd, nscoord aIStart)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mMargin(aBStart, aIEnd, aBEnd, aIStart)
  { }

  LogicalMargin(WritingMode aWritingMode, const nsMargin& aPhysicalMargin)
#ifdef DEBUG
    : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      if (aWritingMode.IsVerticalLR()) {
        mMargin.top = aPhysicalMargin.left;
        mMargin.bottom = aPhysicalMargin.right;
      } else {
        mMargin.top = aPhysicalMargin.right;
        mMargin.bottom = aPhysicalMargin.left;
      }
      if (aWritingMode.IsInlineReversed()) {
        mMargin.left = aPhysicalMargin.bottom;
        mMargin.right = aPhysicalMargin.top;
      } else {
        mMargin.left = aPhysicalMargin.top;
        mMargin.right = aPhysicalMargin.bottom;
      }
    } else {
      mMargin.top = aPhysicalMargin.top;
      mMargin.bottom = aPhysicalMargin.bottom;
      if (aWritingMode.IsInlineReversed()) {
        mMargin.left = aPhysicalMargin.right;
        mMargin.right = aPhysicalMargin.left;
      } else {
        mMargin.left = aPhysicalMargin.left;
        mMargin.right = aPhysicalMargin.right;
      }
    }
  }

  nscoord IStart(WritingMode aWritingMode) const // inline-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.left;
  }
  nscoord IEnd(WritingMode aWritingMode) const // inline-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.right;
  }
  nscoord BStart(WritingMode aWritingMode) const // block-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.top;
  }
  nscoord BEnd(WritingMode aWritingMode) const // block-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.bottom;
  }
  nscoord Start(LogicalAxis aAxis, WritingMode aWM) const
  {
    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
  }
  nscoord End(LogicalAxis aAxis, WritingMode aWM) const
  {
    return aAxis == eLogicalAxisInline ? IEnd(aWM) : BEnd(aWM);
  }

  nscoord& IStart(WritingMode aWritingMode) // inline-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.left;
  }
  nscoord& IEnd(WritingMode aWritingMode) // inline-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.right;
  }
  nscoord& BStart(WritingMode aWritingMode) // block-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.top;
  }
  nscoord& BEnd(WritingMode aWritingMode) // block-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.bottom;
  }
  nscoord& Start(LogicalAxis aAxis, WritingMode aWM)
  {
    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
  }
  nscoord& End(LogicalAxis aAxis, WritingMode aWM)
  {
    return aAxis == eLogicalAxisInline ? IEnd(aWM) : BEnd(aWM);
  }

  nscoord IStartEnd(WritingMode aWritingMode) const // inline margins
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.LeftRight();
  }
  nscoord BStartEnd(WritingMode aWritingMode) const // block margins
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.TopBottom();
  }
  nscoord StartEnd(LogicalAxis aAxis, WritingMode aWM) const
  {
    return aAxis == eLogicalAxisInline ? IStartEnd(aWM) : BStartEnd(aWM);
  }

  /*
   * Return margin values for line-relative sides, as defined in
   * http://www.w3.org/TR/css-writing-modes-3/#line-directions:
   *
   * line-left
   *     Nominally the side from which LTR text would start.
   * line-right
   *     Nominally the side from which RTL text would start. (Opposite of
   *     line-left.)
   */
  nscoord LineLeft(WritingMode aWritingMode) const
  {
    // We don't need to CHECK_WRITING_MODE here because the IStart or IEnd
    // accessor that we call will do it.
    return aWritingMode.IsBidiLTR()
           ? IStart(aWritingMode) : IEnd(aWritingMode);
  }
  nscoord LineRight(WritingMode aWritingMode) const
  {
    return aWritingMode.IsBidiLTR()
           ? IEnd(aWritingMode) : IStart(aWritingMode);
  }

  /**
   * Return a LogicalSize representing the total size of the inline-
   * and block-dimension margins.
   */
  LogicalSize Size(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalSize(aWritingMode, IStartEnd(), BStartEnd());
  }

  /**
   * Accessors for physical margins, using our writing mode to convert from
   * logical values.
   */
  nscoord Top(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ?
      (aWritingMode.IsInlineReversed() ? IEnd() : IStart()) : BStart();
  }

  nscoord Bottom(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ?
      (aWritingMode.IsInlineReversed() ? IStart() : IEnd()) : BEnd();
  }

  nscoord Left(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ?
      (aWritingMode.IsVerticalLR() ? BStart() : BEnd()) :
      (aWritingMode.IsInlineReversed() ? IEnd() : IStart());
  }

  nscoord Right(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ?
      (aWritingMode.IsVerticalLR() ? BEnd() : BStart()) :
      (aWritingMode.IsInlineReversed() ? IStart() : IEnd());
  }

  nscoord LeftRight(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? BStartEnd() : IStartEnd();
  }

  nscoord TopBottom(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? IStartEnd() : BStartEnd();
  }

  void SizeTo(WritingMode aWritingMode,
              nscoord aBStart, nscoord aIEnd, nscoord aBEnd, nscoord aIStart)
  {
    CHECK_WRITING_MODE(aWritingMode);
    mMargin.SizeTo(aBStart, aIEnd, aBEnd, aIStart);
  }

  /**
   * Return an nsMargin containing our physical coordinates
   */
  nsMargin GetPhysicalMargin(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
           ? (aWritingMode.IsVerticalLR()
             ? (aWritingMode.IsInlineReversed()
               ? nsMargin(IEnd(), BEnd(), IStart(), BStart())
               : nsMargin(IStart(), BEnd(), IEnd(), BStart()))
             : (aWritingMode.IsInlineReversed()
               ? nsMargin(IEnd(), BStart(), IStart(), BEnd())
               : nsMargin(IStart(), BStart(), IEnd(), BEnd())))
           : (aWritingMode.IsInlineReversed()
             ? nsMargin(BStart(), IStart(), BEnd(), IEnd())
             : nsMargin(BStart(), IEnd(), BEnd(), IStart()));
  }

  /**
   * Return a LogicalMargin representing this margin in a different
   * writing mode
   */
  LogicalMargin ConvertTo(WritingMode aToMode, WritingMode aFromMode) const
  {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode ?
      *this : LogicalMargin(aToMode, GetPhysicalMargin(aFromMode));
  }

  void ApplySkipSides(LogicalSides aSkipSides)
  {
    if (aSkipSides.BStart()) {
      BStart() = 0;
    }
    if (aSkipSides.BEnd()) {
      BEnd() = 0;
    }
    if (aSkipSides.IStart()) {
      IStart() = 0;
    }
    if (aSkipSides.IEnd()) {
      IEnd() = 0;
    }
  }

  bool IsAllZero() const
  {
    return (mMargin.left == 0 && mMargin.top == 0 &&
            mMargin.right == 0 && mMargin.bottom == 0);
  }

  LogicalMargin operator+(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return LogicalMargin(GetWritingMode(),
                         BStart() + aMargin.BStart(),
                         IEnd() + aMargin.IEnd(),
                         BEnd() + aMargin.BEnd(),
                         IStart() + aMargin.IStart());
  }

  LogicalMargin operator+=(const LogicalMargin& aMargin)
  {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    mMargin += aMargin.mMargin;
    return *this;
  }

  LogicalMargin operator-(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return LogicalMargin(GetWritingMode(),
                         BStart() - aMargin.BStart(),
                         IEnd() - aMargin.IEnd(),
                         BEnd() - aMargin.BEnd(),
                         IStart() - aMargin.IStart());
  }

private:
  friend class LogicalRect;

  LogicalMargin() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord IStart() const // inline-start margin
  {
    return mMargin.left;
  }
  nscoord IEnd() const // inline-end margin
  {
    return mMargin.right;
  }
  nscoord BStart() const // block-start margin
  {
    return mMargin.top;
  }
  nscoord BEnd() const // block-end margin
  {
    return mMargin.bottom;
  }

  nscoord& IStart() // inline-start margin
  {
    return mMargin.left;
  }
  nscoord& IEnd() // inline-end margin
  {
    return mMargin.right;
  }
  nscoord& BStart() // block-start margin
  {
    return mMargin.top;
  }
  nscoord& BEnd() // block-end margin
  {
    return mMargin.bottom;
  }

  nscoord IStartEnd() const // inline margins
  {
    return mMargin.LeftRight();
  }
  nscoord BStartEnd() const // block margins
  {
    return mMargin.TopBottom();
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  nsMargin    mMargin;
};

/**
 * Flow-relative rectangle
 */
class LogicalRect {
public:
  explicit LogicalRect(WritingMode aWritingMode)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mIStart(0),
      mBStart(0),
      mISize(0),
      mBSize(0)
  { }

  LogicalRect(WritingMode aWritingMode,
              nscoord aIStart, nscoord aBStart,
              nscoord aISize, nscoord aBSize)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mIStart(aIStart),
      mBStart(aBStart),
      mISize(aISize),
      mBSize(aBSize)
  { }

  LogicalRect(WritingMode aWritingMode,
              const LogicalPoint& aOrigin,
              const LogicalSize& aSize)
    :
#ifdef DEBUG
      mWritingMode(aWritingMode),
#endif
      mIStart(aOrigin.mPoint.x),
      mBStart(aOrigin.mPoint.y),
      mISize(aSize.mSize.width),
      mBSize(aSize.mSize.height)
  {
    CHECK_WRITING_MODE(aOrigin.GetWritingMode());
    CHECK_WRITING_MODE(aSize.GetWritingMode());
  }

  LogicalRect(WritingMode aWritingMode,
              const nsRect& aRect,
              const nsSize& aContainerSize)
#ifdef DEBUG
    : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      mBStart = aWritingMode.IsVerticalLR()
               ? aRect.X() : aContainerSize.width - aRect.XMost();
      mIStart = aWritingMode.IsInlineReversed()
               ? aContainerSize.height - aRect.YMost() : aRect.Y();
      mBSize = aRect.Width();
      mISize = aRect.Height();
    } else {
      mIStart = aWritingMode.IsInlineReversed()
               ? aContainerSize.width - aRect.XMost() : aRect.X();
      mBStart = aRect.Y();
      mISize = aRect.Width();
      mBSize = aRect.Height();
    }
  }

  /**
   * Inline- and block-dimension geometry.
   */
  nscoord IStart(WritingMode aWritingMode) const // inline-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart;
  }
  nscoord IEnd(WritingMode aWritingMode) const // inline-end edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart + mISize;
  }
  nscoord ISize(WritingMode aWritingMode) const // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mISize;
  }

  nscoord BStart(WritingMode aWritingMode) const // block-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart;
  }
  nscoord BEnd(WritingMode aWritingMode) const // block-end edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart + mBSize;
  }
  nscoord BSize(WritingMode aWritingMode) const // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBSize;
  }

  /**
   * Writable (reference) accessors are only available for the basic logical
   * fields (Start and Size), not derivatives like End.
   */
  nscoord& IStart(WritingMode aWritingMode) // inline-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart;
  }
  nscoord& ISize(WritingMode aWritingMode) // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mISize;
  }
  nscoord& BStart(WritingMode aWritingMode) // block-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart;
  }
  nscoord& BSize(WritingMode aWritingMode) // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBSize;
  }

  /**
   * Accessors for line-relative coordinates
   */
  nscoord LineLeft(WritingMode aWritingMode,
                   const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return IStart();
    }
    nscoord containerISize =
      aWritingMode.IsVertical() ? aContainerSize.height : aContainerSize.width;
    return containerISize - IEnd();
  }
  nscoord LineRight(WritingMode aWritingMode,
                    const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return IEnd();
    }
    nscoord containerISize =
      aWritingMode.IsVertical() ? aContainerSize.height : aContainerSize.width;
    return containerISize - IStart();
  }

  /**
   * Physical coordinates of the rect.
   */
  nscoord X(WritingMode aWritingMode, nscoord aContainerWidth) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsVerticalLR() ?
             mBStart : aContainerWidth - BEnd();
    } else {
      return aWritingMode.IsInlineReversed() ?
             aContainerWidth - IEnd() : mIStart;
    }
  }

  nscoord Y(WritingMode aWritingMode, nscoord aContainerHeight) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsInlineReversed() ? aContainerHeight - IEnd()
                                             : mIStart;
    } else {
      return mBStart;
    }
  }

  nscoord Width(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? mBSize : mISize;
  }

  nscoord Height(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? mISize : mBSize;
  }

  nscoord XMost(WritingMode aWritingMode, nscoord aContainerWidth) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsVerticalLR() ?
             BEnd() : aContainerWidth - mBStart;
    } else {
      return aWritingMode.IsInlineReversed() ?
             aContainerWidth - mIStart : IEnd();
    }
  }

  nscoord YMost(WritingMode aWritingMode, nscoord aContainerHeight) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsInlineReversed() ? aContainerHeight - mIStart
                                             : IEnd();
    } else {
      return mBStart;
    }
  }

  bool IsEmpty() const
  {
    return mISize <= 0 || mBSize <= 0;
  }

  bool IsAllZero() const
  {
    return (mIStart == 0 && mBStart == 0 &&
            mISize == 0 && mBSize == 0);
  }

  bool IsZeroSize() const
  {
    return (mISize == 0 && mBSize == 0);
  }

  void SetEmpty() { mISize = mBSize = 0; }

  bool IsEqualEdges(const LogicalRect aOther) const
  {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    bool result = mIStart == aOther.mIStart && mBStart == aOther.mBStart &&
                  mISize == aOther.mISize && mBSize == aOther.mBSize;

    // We want the same result as nsRect, so assert we get it.
    MOZ_ASSERT(result == nsRect(mIStart, mBStart, mISize, mBSize).
                           IsEqualEdges(nsRect(aOther.mIStart, aOther.mBStart,
                                               aOther.mISize, aOther.mBSize)));
    return result;
  }

  LogicalPoint Origin(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalPoint(aWritingMode, IStart(), BStart());
  }
  void SetOrigin(WritingMode aWritingMode, const LogicalPoint& aPoint)
  {
    IStart(aWritingMode) = aPoint.I(aWritingMode);
    BStart(aWritingMode) = aPoint.B(aWritingMode);
  }

  LogicalSize Size(WritingMode aWritingMode) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalSize(aWritingMode, ISize(), BSize());
  }

  LogicalRect operator+(const LogicalPoint& aPoint) const
  {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    return LogicalRect(GetWritingMode(),
                       IStart() + aPoint.I(), BStart() + aPoint.B(),
                       ISize(), BSize());
  }

  LogicalRect& operator+=(const LogicalPoint& aPoint)
  {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    mIStart += aPoint.mPoint.x;
    mBStart += aPoint.mPoint.y;
    return *this;
  }

  LogicalRect operator-(const LogicalPoint& aPoint) const
  {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    return LogicalRect(GetWritingMode(),
                       IStart() - aPoint.I(), BStart() - aPoint.B(),
                       ISize(), BSize());
  }

  LogicalRect& operator-=(const LogicalPoint& aPoint)
  {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    mIStart -= aPoint.mPoint.x;
    mBStart -= aPoint.mPoint.y;
    return *this;
  }

  void MoveBy(WritingMode aWritingMode, const LogicalPoint& aDelta)
  {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aDelta.GetWritingMode());
    IStart() += aDelta.I();
    BStart() += aDelta.B();
  }

  void Inflate(nscoord aD)
  {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aD);
#endif
    mIStart -= aD;
    mBStart -= aD;
    mISize += 2 * aD;
    mBSize += 2 * aD;
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Inflate(nscoord aDI, nscoord aDB)
  {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aDI, aDB);
#endif
    mIStart -= aDI;
    mBStart -= aDB;
    mISize += 2 * aDI;
    mBSize += 2 * aDB;
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Inflate(WritingMode aWritingMode, const LogicalMargin& aMargin)
  {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aMargin.mMargin);
#endif
    mIStart -= aMargin.mMargin.left;
    mBStart -= aMargin.mMargin.top;
    mISize += aMargin.mMargin.LeftRight();
    mBSize += aMargin.mMargin.TopBottom();
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }

  void Deflate(nscoord aD)
  {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aD);
#endif
    mIStart += aD;
    mBStart += aD;
    mISize = std::max(0, mISize - 2 * aD);
    mBSize = std::max(0, mBSize - 2 * aD);
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Deflate(nscoord aDI, nscoord aDB)
  {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aDI, aDB);
#endif
    mIStart += aDI;
    mBStart += aDB;
    mISize = std::max(0, mISize - 2 * aDI);
    mBSize = std::max(0, mBSize - 2 * aDB);
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Deflate(WritingMode aWritingMode, const LogicalMargin& aMargin)
  {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aMargin.mMargin);
#endif
    mIStart += aMargin.mMargin.left;
    mBStart += aMargin.mMargin.top;
    mISize = std::max(0, mISize - aMargin.mMargin.LeftRight());
    mBSize = std::max(0, mBSize - aMargin.mMargin.TopBottom());
    MOZ_ASSERT(rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }

  /**
   * Return an nsRect containing our physical coordinates within the given
   * container size.
   */
  nsRect GetPhysicalRect(WritingMode aWritingMode,
                         const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return nsRect(aWritingMode.IsVerticalLR()
                    ? BStart() : aContainerSize.width - BEnd(),
                    aWritingMode.IsInlineReversed()
                    ?  aContainerSize.height - IEnd() : IStart(),
                    BSize(), ISize());
    } else {
      return nsRect(aWritingMode.IsInlineReversed()
                    ? aContainerSize.width - IEnd() : IStart(),
                    BStart(), ISize(), BSize());
    }
  }

  /**
   * Return a LogicalRect representing this rect in a different writing mode
   */
  LogicalRect ConvertTo(WritingMode aToMode, WritingMode aFromMode,
                        const nsSize& aContainerSize) const
  {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode ?
      *this : LogicalRect(aToMode, GetPhysicalRect(aFromMode, aContainerSize),
                          aContainerSize);
  }

  /**
   * Set *this to be the rectangle containing the intersection of aRect1
   * and aRect2, return whether the intersection is non-empty.
   */
  bool IntersectRect(const LogicalRect& aRect1, const LogicalRect& aRect2)
  {
    CHECK_WRITING_MODE(aRect1.mWritingMode);
    CHECK_WRITING_MODE(aRect2.mWritingMode);
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug;
    rectDebug.IntersectRect(nsRect(aRect1.mIStart, aRect1.mBStart,
                                   aRect1.mISize, aRect1.mBSize),
                            nsRect(aRect2.mIStart, aRect2.mBStart,
                                   aRect2.mISize, aRect2.mBSize));
#endif

    nscoord iEnd = std::min(aRect1.IEnd(), aRect2.IEnd());
    mIStart = std::max(aRect1.mIStart, aRect2.mIStart);
    mISize = iEnd - mIStart;

    nscoord bEnd = std::min(aRect1.BEnd(), aRect2.BEnd());
    mBStart = std::max(aRect1.mBStart, aRect2.mBStart);
    mBSize = bEnd - mBStart;

    if (mISize < 0 || mBSize < 0) {
      mISize = 0;
      mBSize = 0;
    }

    MOZ_ASSERT((rectDebug.IsEmpty() && (mISize == 0 || mBSize == 0)) || rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
    return mISize > 0 && mBSize > 0;
  }

private:
  LogicalRect() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord IStart() const // inline-start edge
  {
    return mIStart;
  }
  nscoord IEnd() const // inline-end edge
  {
    return mIStart + mISize;
  }
  nscoord ISize() const // inline-size
  {
    return mISize;
  }

  nscoord BStart() const // block-start edge
  {
    return mBStart;
  }
  nscoord BEnd() const // block-end edge
  {
    return mBStart + mBSize;
  }
  nscoord BSize() const // block-size
  {
    return mBSize;
  }

  nscoord& IStart() // inline-start edge
  {
    return mIStart;
  }
  nscoord& ISize() // inline-size
  {
    return mISize;
  }
  nscoord& BStart() // block-start edge
  {
    return mBStart;
  }
  nscoord& BSize() // block-size
  {
    return mBSize;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  // Inline- and block-geometry dimension
  nscoord     mIStart; // inline-start edge
  nscoord     mBStart; // block-start edge
  nscoord     mISize; // inline-size
  nscoord     mBSize; // block-size
};

} // namespace mozilla

// Definitions of inline methods for nsStyleSides, declared in nsStyleCoord.h
// but not defined there because they need WritingMode.
inline nsStyleUnit nsStyleSides::GetUnit(mozilla::WritingMode aWM,
                                         mozilla::LogicalSide aSide) const
{
  return GetUnit(aWM.PhysicalSide(aSide));
}

inline nsStyleUnit nsStyleSides::GetIStartUnit(mozilla::WritingMode aWM) const
{
  return GetUnit(aWM, mozilla::eLogicalSideIStart);
}

inline nsStyleUnit nsStyleSides::GetBStartUnit(mozilla::WritingMode aWM) const
{
  return GetUnit(aWM, mozilla::eLogicalSideBStart);
}

inline nsStyleUnit nsStyleSides::GetIEndUnit(mozilla::WritingMode aWM) const
{
  return GetUnit(aWM, mozilla::eLogicalSideIEnd);
}

inline nsStyleUnit nsStyleSides::GetBEndUnit(mozilla::WritingMode aWM) const
{
  return GetUnit(aWM, mozilla::eLogicalSideBEnd);
}

inline bool nsStyleSides::HasBlockAxisAuto(mozilla::WritingMode aWM) const
{
  return GetBStartUnit(aWM) == eStyleUnit_Auto ||
         GetBEndUnit(aWM) == eStyleUnit_Auto;
}

inline bool nsStyleSides::HasInlineAxisAuto(mozilla::WritingMode aWM) const
{
  return GetIStartUnit(aWM) == eStyleUnit_Auto ||
         GetIEndUnit(aWM) == eStyleUnit_Auto;
}

inline nsStyleCoord nsStyleSides::Get(mozilla::WritingMode aWM,
                                      mozilla::LogicalSide aSide) const
{
  return Get(aWM.PhysicalSide(aSide));
}

inline nsStyleCoord nsStyleSides::GetIStart(mozilla::WritingMode aWM) const
{
  return Get(aWM, mozilla::eLogicalSideIStart);
}

inline nsStyleCoord nsStyleSides::GetBStart(mozilla::WritingMode aWM) const
{
  return Get(aWM, mozilla::eLogicalSideBStart);
}

inline nsStyleCoord nsStyleSides::GetIEnd(mozilla::WritingMode aWM) const
{
  return Get(aWM, mozilla::eLogicalSideIEnd);
}

inline nsStyleCoord nsStyleSides::GetBEnd(mozilla::WritingMode aWM) const
{
  return Get(aWM, mozilla::eLogicalSideBEnd);
}

// Definitions of inline methods for nsStylePosition, declared in
// nsStyleStruct.h but not defined there because they need WritingMode.
inline nsStyleCoord& nsStylePosition::ISize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mHeight : mWidth;
}
inline nsStyleCoord& nsStylePosition::MinISize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mMinHeight : mMinWidth;
}
inline nsStyleCoord& nsStylePosition::MaxISize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mMaxHeight : mMaxWidth;
}
inline nsStyleCoord& nsStylePosition::BSize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mWidth : mHeight;
}
inline nsStyleCoord& nsStylePosition::MinBSize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mMinWidth : mMinHeight;
}
inline nsStyleCoord& nsStylePosition::MaxBSize(mozilla::WritingMode aWM)
{
  return aWM.IsVertical() ? mMaxWidth : mMaxHeight;
}

inline const nsStyleCoord&
nsStylePosition::ISize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mHeight : mWidth;
}
inline const nsStyleCoord&
nsStylePosition::MinISize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mMinHeight : mMinWidth;
}
inline const nsStyleCoord&
nsStylePosition::MaxISize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mMaxHeight : mMaxWidth;
}
inline const nsStyleCoord&
nsStylePosition::BSize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mWidth : mHeight;
}
inline const nsStyleCoord&
nsStylePosition::MinBSize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mMinWidth : mMinHeight;
}
inline const nsStyleCoord&
nsStylePosition::MaxBSize(mozilla::WritingMode aWM) const
{
  return aWM.IsVertical() ? mMaxWidth : mMaxHeight;
}

inline bool
nsStylePosition::ISizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  const auto& iSize = aWM.IsVertical() ? mHeight : mWidth;
  return iSize.GetUnit() == eStyleUnit_Auto ||
         ISizeCoordDependsOnContainer(iSize);
}
inline bool
nsStylePosition::MinISizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  // NOTE: For a flex item, "min-inline-size:auto" is supposed to behave like
  // "min-content", which does depend on the container, so you might think we'd
  // need a special case for "flex item && min-inline-size:auto" here. However,
  // we don't actually need that special-case code, because flex items are
  // explicitly supposed to *ignore* their min-inline-size (i.e. behave like
  // it's 0) until the flex container explicitly considers it. So -- since the
  // flex container doesn't rely on this method, we don't need to worry about
  // special behavior for flex items' "min-inline-size:auto" values here.
  return ISizeCoordDependsOnContainer(MinISize(aWM));
}
inline bool
nsStylePosition::MaxISizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  // NOTE: The comment above MinISizeDependsOnContainer about flex items
  // applies here, too.
  return ISizeCoordDependsOnContainer(MaxISize(aWM));
}
// Note that these functions count `auto` as depending on the container
// since that's the case for absolutely positioned elements.
// However, some callers do not care about this case and should check
// for it, since it is the most common case.
// FIXME: We should probably change the assumption to be the other way
// around.
inline bool
nsStylePosition::BSizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  const auto& bSize = aWM.IsVertical() ? mWidth : mHeight;
  return bSize.IsAutoOrEnum() || BSizeCoordDependsOnContainer(bSize);
}
inline bool
nsStylePosition::MinBSizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  return BSizeCoordDependsOnContainer(MinBSize(aWM));
}
inline bool
nsStylePosition::MaxBSizeDependsOnContainer(mozilla::WritingMode aWM) const
{
  return BSizeCoordDependsOnContainer(MaxBSize(aWM));
}

inline bool
nsStyleMargin::HasBlockAxisAuto(mozilla::WritingMode aWM) const
{
  return mMargin.HasBlockAxisAuto(aWM);
}
inline bool
nsStyleMargin::HasInlineAxisAuto(mozilla::WritingMode aWM) const
{
  return mMargin.HasInlineAxisAuto(aWM);
}

#endif // WritingModes_h_