gecko-dev/layout/style/nsStyleCoord.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* representation of length values in computed style data */

#ifndef nsStyleCoord_h___
#define nsStyleCoord_h___

#include <type_traits>

#include "mozilla/EnumTypeTraits.h"
#include "nsCoord.h"
#include "nsStyleConsts.h"

namespace mozilla {

class WritingMode;

// Logical axis, edge, side and corner constants for use in various places.
enum LogicalAxis {
  eLogicalAxisBlock  = 0x0,
  eLogicalAxisInline = 0x1
};
enum LogicalEdge {
  eLogicalEdgeStart  = 0x0,
  eLogicalEdgeEnd    = 0x1
};
enum LogicalSide {
  eLogicalSideBStart = (eLogicalAxisBlock  << 1) | eLogicalEdgeStart,  // 0x0
  eLogicalSideBEnd   = (eLogicalAxisBlock  << 1) | eLogicalEdgeEnd,    // 0x1
  eLogicalSideIStart = (eLogicalAxisInline << 1) | eLogicalEdgeStart,  // 0x2
  eLogicalSideIEnd   = (eLogicalAxisInline << 1) | eLogicalEdgeEnd     // 0x3
};

enum LogicalCorner
{
  eLogicalCornerBStartIStart = 0,
  eLogicalCornerBStartIEnd   = 1,
  eLogicalCornerBEndIEnd     = 2,
  eLogicalCornerBEndIStart   = 3
};

} // namespace mozilla

enum nsStyleUnit : uint8_t {
  eStyleUnit_Null         = 0,      // (no value) value is not specified
  eStyleUnit_Normal       = 1,      // (no value)
  eStyleUnit_Auto         = 2,      // (no value)
  eStyleUnit_None         = 3,      // (no value)
  eStyleUnit_Percent      = 10,     // (float) 1.0 == 100%
  eStyleUnit_Factor       = 11,     // (float) a multiplier
  eStyleUnit_Degree       = 12,     // (float) angle in degrees
  eStyleUnit_Grad         = 13,     // (float) angle in grads
  eStyleUnit_Radian       = 14,     // (float) angle in radians
  eStyleUnit_Turn         = 15,     // (float) angle in turns
  eStyleUnit_FlexFraction = 16,     // (float) <flex> in fr units
  eStyleUnit_Coord        = 20,     // (nscoord) value is twips
  eStyleUnit_Integer      = 30,     // (int) value is simple integer
  eStyleUnit_Enumerated   = 32,     // (int) value has enumerated meaning

  // The following are reference counted allocated types.
  eStyleUnit_Calc         = 40,     // (Calc*) calc() toplevel; always present
                                    // to distinguish 50% from calc(50%), etc.

  eStyleUnit_MAX          = 40      // highest valid nsStyleUnit value
};

typedef union {
  int32_t     mInt;   // nscoord is a int32_t for now
  float       mFloat;
  // An mPointer is a reference counted pointer.  Currently this can only
  // ever be an nsStyleCoord::Calc*.
  void*       mPointer;
} nsStyleUnion;

/**
 * Class that hold a single size specification used by the style
 * system.  The size specification consists of two parts -- a number
 * and a unit.  The number is an integer, a floating point value, an
 * nscoord, or undefined, and the unit is an nsStyleUnit.  Checking
 * the unit is a must before asking for the value in any particular
 * form.
 */
 /** <div rustbindgen private accessor="unsafe"></div> */
class nsStyleCoord {
public:
  // Non-reference counted calc() value.  See nsStyleStruct.h for some uses
  // of this.
  struct CalcValue {
    // Every calc() expression evaluates to a length plus a percentage.
    nscoord mLength;
    float mPercent;
    bool mHasPercent; // whether there was any % syntax, even if 0

    bool operator==(const CalcValue& aOther) const {
      return mLength == aOther.mLength &&
             mPercent == aOther.mPercent &&
             mHasPercent == aOther.mHasPercent;
    }
    bool operator!=(const CalcValue& aOther) const {
      return !(*this == aOther);
    }

    nscoord ToLength() const {
      MOZ_ASSERT(!mHasPercent);
      return mLength;
    }

    // If this returns true the value is definitely zero. It it returns false
    // it might be zero. So it's best used for conservative optimization.
    bool IsDefinitelyZero() const { return mLength == 0 && mPercent == 0; }
  };

  // Reference counted calc() value.  This is the type that is used to store
  // the calc() value in nsStyleCoord.
  struct Calc final : public CalcValue {
    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(Calc)
    Calc() {}

  private:
    Calc(const Calc&) = delete;
    ~Calc() {}
    Calc& operator=(const Calc&) = delete;
  };

  explicit nsStyleCoord(nsStyleUnit aUnit = eStyleUnit_Null);
  enum CoordConstructorType { CoordConstructor };
  inline nsStyleCoord(nscoord aValue, CoordConstructorType);
  nsStyleCoord(int32_t aValue, nsStyleUnit aUnit);
  nsStyleCoord(float aValue, nsStyleUnit aUnit);
  inline nsStyleCoord(const nsStyleCoord& aCopy);
  inline nsStyleCoord(const nsStyleUnion& aValue, nsStyleUnit aUnit);
  ~nsStyleCoord() { Reset(); }

  nsStyleCoord&  operator=(const nsStyleCoord& aOther)
  {
    if (this != &aOther) {
      SetValue(mUnit, mValue, aOther);
    }
    return *this;
  }
  bool           operator==(const nsStyleCoord& aOther) const;
  bool           operator!=(const nsStyleCoord& aOther) const;

  nsStyleUnit GetUnit() const {
    NS_ASSERTION(mUnit != eStyleUnit_Null, "reading uninitialized value");
    return mUnit;
  }

  bool IsAngleValue() const {
    return eStyleUnit_Degree <= mUnit && mUnit <= eStyleUnit_Turn;
  }

  static bool IsCalcUnit(nsStyleUnit aUnit) {
    return aUnit == eStyleUnit_Calc;
  }

  static bool IsPointerUnit(nsStyleUnit aUnit) {
    return IsCalcUnit(aUnit);
  }

  bool IsCalcUnit() const {
    return IsCalcUnit(mUnit);
  }

  bool IsPointerValue() const {
    return IsPointerUnit(mUnit);
  }

  bool IsCoordPercentCalcUnit() const {
    return mUnit == eStyleUnit_Coord ||
           mUnit == eStyleUnit_Percent ||
           IsCalcUnit();
  }

  // Does this calc() expression have any percentages inside it?  Can be
  // called only when IsCalcUnit() is true.
  bool CalcHasPercent() const {
    return GetCalcValue()->mHasPercent;
  }

  bool HasPercent() const {
    return mUnit == eStyleUnit_Percent ||
           (IsCalcUnit() && CalcHasPercent());
  }

  static bool ConvertsToLength(const nsStyleUnit aUnit,
                               const nsStyleUnion aValue) {
    return aUnit == eStyleUnit_Coord ||
           (IsCalcUnit(aUnit) && !AsCalcValue(aValue)->mHasPercent);
  }

  bool ConvertsToLength() const {
    return ConvertsToLength(mUnit, mValue);
  }

  static nscoord ToLength(nsStyleUnit aUnit, nsStyleUnion aValue) {
    MOZ_ASSERT(ConvertsToLength(aUnit, aValue));
    if (IsCalcUnit(aUnit)) {
      return AsCalcValue(aValue)->ToLength(); // Note: This asserts !mHasPercent
    }
    MOZ_ASSERT(aUnit == eStyleUnit_Coord);
    return aValue.mInt;
  }

  nscoord ToLength() const {
    return ToLength(GetUnit(), mValue);
  }

  // Callers must verify IsCalcUnit before calling this function.
  static Calc* AsCalcValue(nsStyleUnion aValue) {
    return static_cast<Calc*>(aValue.mPointer);
  }

  nscoord     GetCoordValue() const;
  int32_t     GetIntValue() const;
  float       GetPercentValue() const;
  float       GetFactorValue() const;
  float       GetFactorOrPercentValue() const;
  float       GetAngleValue() const;
  double      GetAngleValueInDegrees() const;
  double      GetAngleValueInRadians() const;
  float       GetFlexFractionValue() const;
  Calc*       GetCalcValue() const;
  uint32_t    HashValue(uint32_t aHash) const;
  template<typename T,
           typename = typename std::enable_if<std::is_enum<T>::value>::type>
  T GetEnumValue() const
  {
    MOZ_ASSERT(GetUnit() == eStyleUnit_Enumerated,
               "The unit must be eStyleUnit_Enumerated!");
    return static_cast<T>(GetIntValue());
  }

  // Sets to null and releases any refcounted objects.  Only use this if the
  // object is initialized (i.e. don't use it in nsStyleCoord constructors).
  void Reset();

  void  SetCoordValue(nscoord aValue);
  void  SetIntValue(int32_t aValue, nsStyleUnit aUnit);
  void  SetPercentValue(float aValue);
  void  SetFactorValue(float aValue);
  void  SetAngleValue(float aValue, nsStyleUnit aUnit);
  void  SetFlexFractionValue(float aValue);
  void  SetNormalValue();
  void  SetAutoValue();
  void  SetNoneValue();
  void  SetCalcValue(Calc* aValue);
  template<typename T,
           typename = typename std::enable_if<std::is_enum<T>::value>::type>
  void SetEnumValue(T aValue)
  {
    static_assert(mozilla::EnumTypeFitsWithin<T, int32_t>::value,
                  "aValue must be an enum that fits within mValue.mInt!");
    SetIntValue(static_cast<int32_t>(aValue), eStyleUnit_Enumerated);
  }

  // Resets a coord represented by a unit/value pair.
  static inline void Reset(nsStyleUnit& aUnit, nsStyleUnion& aValue);

  // Sets a coord represented by a unit/value pair from a second
  // unit/value pair.
  static inline void SetValue(nsStyleUnit& aUnit,
                              nsStyleUnion& aValue,
                              nsStyleUnit aOtherUnit,
                              const nsStyleUnion& aOtherValue);

  // Sets a coord represented by a unit/value pair from an nsStyleCoord.
  static inline void SetValue(nsStyleUnit& aUnit, nsStyleUnion& aValue,
                              const nsStyleCoord& aOther);

  // Like the above, but do not reset before setting.
  static inline void InitWithValue(nsStyleUnit& aUnit,
                                   nsStyleUnion& aValue,
                                   nsStyleUnit aOtherUnit,
                                   const nsStyleUnion& aOtherValue);

  static inline void InitWithValue(nsStyleUnit& aUnit, nsStyleUnion& aValue,
                                   const nsStyleCoord& aOther);

private:
  nsStyleUnit   mUnit;
  nsStyleUnion  mValue;
};

/**
 * Class that represents a set of top/right/bottom/left nsStyleCoords.
 * This is commonly used to hold the widths of the borders, margins,
 * or paddings of a box.
 */
 /** <div rustbindgen private accessor="unsafe"></div> */
class nsStyleSides {
public:
  nsStyleSides();
  nsStyleSides(const nsStyleSides&);
  ~nsStyleSides();

  nsStyleSides&  operator=(const nsStyleSides& aCopy);
  bool           operator==(const nsStyleSides& aOther) const;
  bool           operator!=(const nsStyleSides& aOther) const;

  inline nsStyleUnit GetUnit(mozilla::Side aSide) const;
  inline nsStyleUnit GetLeftUnit() const;
  inline nsStyleUnit GetTopUnit() const;
  inline nsStyleUnit GetRightUnit() const;
  inline nsStyleUnit GetBottomUnit() const;

  inline nsStyleCoord Get(mozilla::Side aSide) const;
  inline nsStyleCoord GetLeft() const;
  inline nsStyleCoord GetTop() const;
  inline nsStyleCoord GetRight() const;
  inline nsStyleCoord GetBottom() const;

  // Methods to access the units and values in terms of logical sides
  // for a given writing mode.
  // NOTE: The definitions are in WritingModes.h (after we have the full
  // declaration of WritingMode available).
  inline nsStyleUnit GetUnit(mozilla::WritingMode aWritingMode,
                             mozilla::LogicalSide aSide) const;
  inline nsStyleUnit GetIStartUnit(mozilla::WritingMode aWritingMode) const;
  inline nsStyleUnit GetBStartUnit(mozilla::WritingMode aWritingMode) const;
  inline nsStyleUnit GetIEndUnit(mozilla::WritingMode aWritingMode) const;
  inline nsStyleUnit GetBEndUnit(mozilla::WritingMode aWritingMode) const;

  // Return true if either the start or end side in the axis is 'auto'.
  inline bool HasBlockAxisAuto(mozilla::WritingMode aWritingMode) const;
  inline bool HasInlineAxisAuto(mozilla::WritingMode aWritingMode) const;

  inline nsStyleCoord Get(mozilla::WritingMode aWritingMode,
                          mozilla::LogicalSide aSide) const;
  inline nsStyleCoord GetIStart(mozilla::WritingMode aWritingMode) const;
  inline nsStyleCoord GetBStart(mozilla::WritingMode aWritingMode) const;
  inline nsStyleCoord GetIEnd(mozilla::WritingMode aWritingMode) const;
  inline nsStyleCoord GetBEnd(mozilla::WritingMode aWritingMode) const;

  // Sets each side to null and releases any refcounted objects.  Only use this
  // if the object is initialized (i.e. don't use it in nsStyleSides
  // constructors).
  void Reset();

  inline void Set(mozilla::Side aSide, const nsStyleCoord& aCoord);
  inline void SetLeft(const nsStyleCoord& aCoord);
  inline void SetTop(const nsStyleCoord& aCoord);
  inline void SetRight(const nsStyleCoord& aCoord);
  inline void SetBottom(const nsStyleCoord& aCoord);

  nscoord ToLength(mozilla::Side aSide) const {
    return nsStyleCoord::ToLength(mUnits[aSide], mValues[aSide]);
  }

  bool ConvertsToLength() const {
    NS_FOR_CSS_SIDES(side) {
      if (!nsStyleCoord::ConvertsToLength(mUnits[side], mValues[side])) {
        return false;
      }
    }
    return true;
  }

protected:
  nsStyleUnit   mUnits[4];
  nsStyleUnion  mValues[4];
};

/**
 * Class that represents a set of top-left/top-right/bottom-right/bottom-left
 * nsStyleCoord pairs.  This is used to hold the dimensions of the
 * corners of a box (for, e.g., border-radius and outline-radius).
 */
 /** <div rustbindgen private accessor="unsafe"></div> */
class nsStyleCorners {
public:
  nsStyleCorners();
  nsStyleCorners(const nsStyleCorners&);
  ~nsStyleCorners();

  // use compiler's version
  nsStyleCorners& operator=(const nsStyleCorners& aCopy);
  bool           operator==(const nsStyleCorners& aOther) const;
  bool           operator!=(const nsStyleCorners& aOther) const;

  // aHalfCorner is always one of enum HalfCorner in gfx/2d/Types.h.
  inline nsStyleUnit GetUnit(uint8_t aHalfCorner) const;

  inline nsStyleCoord Get(uint8_t aHalfCorner) const;

  // Sets each corner to null and releases any refcounted objects.  Only use
  // this if the object is initialized (i.e. don't use it in nsStyleCorners
  // constructors).
  void Reset();

  inline void Set(uint8_t aHalfCorner, const nsStyleCoord& aCoord);

protected:
  // Stored as:
  // top-left.x, top-left.y,
  // top-right.x, top-right.y,
  // bottom-right.x, bottom-right.y,
  // bottom-left.x, bottom-left.y
  nsStyleUnit   mUnits[8];
  nsStyleUnion  mValues[8];
};


// -------------------------
// nsStyleCoord inlines
//
inline nsStyleCoord::nsStyleCoord(nscoord aValue, CoordConstructorType)
  : mUnit(eStyleUnit_Coord)
{
  mValue.mInt = aValue;
}

inline nsStyleCoord::nsStyleCoord(const nsStyleCoord& aCopy)
  : mUnit(eStyleUnit_Null)
{
  InitWithValue(mUnit, mValue, aCopy);
}

inline nsStyleCoord::nsStyleCoord(const nsStyleUnion& aValue, nsStyleUnit aUnit)
  : mUnit(eStyleUnit_Null)
{
  InitWithValue(mUnit, mValue, aUnit, aValue);
}

inline bool nsStyleCoord::operator!=(const nsStyleCoord& aOther) const
{
  return !((*this) == aOther);
}

inline nscoord nsStyleCoord::GetCoordValue() const
{
  NS_ASSERTION((mUnit == eStyleUnit_Coord), "not a coord value");
  if (mUnit == eStyleUnit_Coord) {
    return mValue.mInt;
  }
  return 0;
}

inline int32_t nsStyleCoord::GetIntValue() const
{
  NS_ASSERTION((mUnit == eStyleUnit_Enumerated) ||
               (mUnit == eStyleUnit_Integer), "not an int value");
  if ((mUnit == eStyleUnit_Enumerated) ||
      (mUnit == eStyleUnit_Integer)) {
    return mValue.mInt;
  }
  return 0;
}

inline float nsStyleCoord::GetPercentValue() const
{
  NS_ASSERTION(mUnit == eStyleUnit_Percent, "not a percent value");
  if (mUnit == eStyleUnit_Percent) {
    return mValue.mFloat;
  }
  return 0.0f;
}

inline float nsStyleCoord::GetFactorValue() const
{
  NS_ASSERTION(mUnit == eStyleUnit_Factor, "not a factor value");
  if (mUnit == eStyleUnit_Factor) {
    return mValue.mFloat;
  }
  return 0.0f;
}

inline float nsStyleCoord::GetFactorOrPercentValue() const
{
  NS_ASSERTION(mUnit == eStyleUnit_Factor || mUnit == eStyleUnit_Percent,
               "not a percent or factor value");
  if (mUnit == eStyleUnit_Factor || mUnit == eStyleUnit_Percent) {
    return mValue.mFloat;
  }
  return 0.0f;
}

inline float nsStyleCoord::GetAngleValue() const
{
  NS_ASSERTION(mUnit >= eStyleUnit_Degree &&
               mUnit <= eStyleUnit_Turn, "not an angle value");
  if (mUnit >= eStyleUnit_Degree && mUnit <= eStyleUnit_Turn) {
    return mValue.mFloat;
  }
  return 0.0f;
}

inline float nsStyleCoord::GetFlexFractionValue() const
{
  NS_ASSERTION(mUnit == eStyleUnit_FlexFraction, "not a fr value");
  if (mUnit == eStyleUnit_FlexFraction) {
    return mValue.mFloat;
  }
  return 0.0f;
}

inline nsStyleCoord::Calc* nsStyleCoord::GetCalcValue() const
{
  NS_ASSERTION(IsCalcUnit(), "not a pointer value");
  if (IsCalcUnit()) {
    return AsCalcValue(mValue);
  }
  return nullptr;
}

/* static */ inline void
nsStyleCoord::Reset(nsStyleUnit& aUnit, nsStyleUnion& aValue)
{
  MOZ_ASSERT(aUnit <= eStyleUnit_MAX,
             "calling Reset on uninitialized nsStyleCoord?");

  switch (aUnit) {
    case eStyleUnit_Calc:
      static_cast<Calc*>(aValue.mPointer)->Release();
      break;
    default:
      MOZ_ASSERT(!IsPointerUnit(aUnit), "check pointer refcounting logic");
  }

  aUnit = eStyleUnit_Null;
  aValue.mInt = 0;
}

/* static */ inline void
nsStyleCoord::SetValue(nsStyleUnit& aUnit,
                       nsStyleUnion& aValue,
                       nsStyleUnit aOtherUnit,
                       const nsStyleUnion& aOtherValue)
{
  Reset(aUnit, aValue);
  InitWithValue(aUnit, aValue, aOtherUnit, aOtherValue);
}

/* static */ inline void
nsStyleCoord::InitWithValue(nsStyleUnit& aUnit,
                            nsStyleUnion& aValue,
                            nsStyleUnit aOtherUnit,
                            const nsStyleUnion& aOtherValue)
{
  aUnit = aOtherUnit;
  aValue = aOtherValue;

  switch (aUnit) {
    case eStyleUnit_Calc:
      static_cast<Calc*>(aValue.mPointer)->AddRef();
      break;
    default:
      MOZ_ASSERT(!IsPointerUnit(aUnit), "check pointer refcounting logic");
  }
}

/* static */ inline void
nsStyleCoord::SetValue(nsStyleUnit& aUnit, nsStyleUnion& aValue,
                       const nsStyleCoord& aOther)
{
  SetValue(aUnit, aValue, aOther.mUnit, aOther.mValue);
}

/* static */ inline void
nsStyleCoord::InitWithValue(nsStyleUnit& aUnit, nsStyleUnion& aValue,
                            const nsStyleCoord& aOther)
{
  InitWithValue(aUnit, aValue, aOther.mUnit, aOther.mValue);
}


// -------------------------
// nsStyleSides inlines
//
inline bool nsStyleSides::operator!=(const nsStyleSides& aOther) const
{
  return !((*this) == aOther);
}

inline nsStyleUnit nsStyleSides::GetUnit(mozilla::Side aSide) const
{
  return (nsStyleUnit)mUnits[aSide];
}

inline nsStyleUnit nsStyleSides::GetLeftUnit() const
{
  return GetUnit(mozilla::eSideLeft);
}

inline nsStyleUnit nsStyleSides::GetTopUnit() const
{
  return GetUnit(mozilla::eSideTop);
}

inline nsStyleUnit nsStyleSides::GetRightUnit() const
{
  return GetUnit(mozilla::eSideRight);
}

inline nsStyleUnit nsStyleSides::GetBottomUnit() const
{
  return GetUnit(mozilla::eSideBottom);
}

inline nsStyleCoord nsStyleSides::Get(mozilla::Side aSide) const
{
  return nsStyleCoord(mValues[aSide], nsStyleUnit(mUnits[aSide]));
}

inline nsStyleCoord nsStyleSides::GetLeft() const
{
  return Get(mozilla::eSideLeft);
}

inline nsStyleCoord nsStyleSides::GetTop() const
{
  return Get(mozilla::eSideTop);
}

inline nsStyleCoord nsStyleSides::GetRight() const
{
  return Get(mozilla::eSideRight);
}

inline nsStyleCoord nsStyleSides::GetBottom() const
{
  return Get(mozilla::eSideBottom);
}

inline void nsStyleSides::Set(mozilla::Side aSide, const nsStyleCoord& aCoord)
{
  nsStyleCoord::SetValue(mUnits[aSide], mValues[aSide], aCoord);
}

inline void nsStyleSides::SetLeft(const nsStyleCoord& aCoord)
{
  Set(mozilla::eSideLeft, aCoord);
}

inline void nsStyleSides::SetTop(const nsStyleCoord& aCoord)
{
  Set(mozilla::eSideTop, aCoord);
}

inline void nsStyleSides::SetRight(const nsStyleCoord& aCoord)
{
  Set(mozilla::eSideRight, aCoord);
}

inline void nsStyleSides::SetBottom(const nsStyleCoord& aCoord)
{
  Set(mozilla::eSideBottom, aCoord);
}

// -------------------------
// nsStyleCorners inlines
//
inline bool nsStyleCorners::operator!=(const nsStyleCorners& aOther) const
{
  return !((*this) == aOther);
}

inline nsStyleUnit nsStyleCorners::GetUnit(uint8_t aCorner) const
{
  return (nsStyleUnit)mUnits[aCorner];
}

inline nsStyleCoord nsStyleCorners::Get(uint8_t aCorner) const
{
  return nsStyleCoord(mValues[aCorner], nsStyleUnit(mUnits[aCorner]));
}

inline void nsStyleCorners::Set(uint8_t aCorner, const nsStyleCoord& aCoord)
{
  nsStyleCoord::SetValue(mUnits[aCorner], mValues[aCorner], aCoord);
}

#endif /* nsStyleCoord_h___ */