flutter_flutter/sky/engine/platform/Length.h

/*
    Copyright (C) 1999 Lars Knoll (knoll@kde.org)
    Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
    Copyright (C) 2011 Rik Cabanier (cabanier@adobe.com)
    Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/

#ifndef SKY_ENGINE_PLATFORM_LENGTH_H_
#define SKY_ENGINE_PLATFORM_LENGTH_H_

#include <cstring>
#include "flutter/sky/engine/platform/PlatformExport.h"
#include "flutter/sky/engine/platform/animation/AnimationUtilities.h"
#include "flutter/sky/engine/wtf/Assertions.h"
#include "flutter/sky/engine/wtf/FastAllocBase.h"
#include "flutter/sky/engine/wtf/Forward.h"
#include "flutter/sky/engine/wtf/HashMap.h"
#include "flutter/sky/engine/wtf/MathExtras.h"
#include "flutter/sky/engine/wtf/Vector.h"

namespace blink {

// FIXME: This enum makes it hard to tell in general what values may be
// appropriate for any given Length.
enum LengthType {
  Auto,
  Percent,
  Fixed,
  Intrinsic,
  MinIntrinsic,
  MinContent,
  MaxContent,
  FillAvailable,
  FitContent,
  Calculated,
  DeviceWidth,
  DeviceHeight,
  MaxSizeNone
};

enum ValueRange { ValueRangeAll, ValueRangeNonNegative };

struct PixelsAndPercent {
  PixelsAndPercent(float pixels, float percent)
      : pixels(pixels), percent(percent) {}
  float pixels;
  float percent;
};

class CalculationValue;

class PLATFORM_EXPORT Length {
  WTF_MAKE_FAST_ALLOCATED;

 public:
  Length() : m_intValue(0), m_quirk(false), m_type(Auto), m_isFloat(false) {}

  Length(LengthType t)
      : m_intValue(0), m_quirk(false), m_type(t), m_isFloat(false) {
    ASSERT(t != Calculated);
  }

  Length(int v, LengthType t, bool q = false)
      : m_intValue(v), m_quirk(q), m_type(t), m_isFloat(false) {
    ASSERT(t != Calculated);
  }

  Length(LayoutUnit v, LengthType t, bool q = false)
      : m_floatValue(v.toFloat()), m_quirk(q), m_type(t), m_isFloat(true) {
    ASSERT(t != Calculated);
  }

  Length(float v, LengthType t, bool q = false)
      : m_floatValue(v), m_quirk(q), m_type(t), m_isFloat(true) {
    ASSERT(t != Calculated);
  }

  Length(double v, LengthType t, bool q = false)
      : m_quirk(q), m_type(t), m_isFloat(true) {
    m_floatValue = static_cast<float>(v);
  }

  explicit Length(PassRefPtr<CalculationValue>);

  Length(const Length& length) {
    memcpy(this, &length, sizeof(Length));
    if (isCalculated())
      incrementCalculatedRef();
  }

  Length& operator=(const Length& length) {
    if (length.isCalculated())
      length.incrementCalculatedRef();
    if (isCalculated())
      decrementCalculatedRef();
    memcpy(this, &length, sizeof(Length));
    return *this;
  }

  Length(Length&& length) {
    memcpy(this, &length, sizeof(Length));

    // Reset |length|'s type to Auto to make sure its destructor
    // won't call decrementCalculatedRef() as we don't call
    // incrementCalculatedRef() here.
    length.m_type = Auto;
  }

  Length& operator=(Length&& length) {
    if (this == &length)
      return *this;

    if (isCalculated())
      decrementCalculatedRef();

    memcpy(this, &length, sizeof(Length));

    // Reset |length|'s type to Auto to make sure its destructor
    // won't call decrementCalculatedRef() as we don't call
    // incrementCalculatedRef() here.
    length.m_type = Auto;

    return *this;
  }

  ~Length() {
    if (isCalculated())
      decrementCalculatedRef();
  }

  bool operator==(const Length& o) const {
    return (m_type == o.m_type) && (m_quirk == o.m_quirk) &&
           (isMaxSizeNone() || (getFloatValue() == o.getFloatValue()) ||
            isCalculatedEqual(o));
  }
  bool operator!=(const Length& o) const { return !(*this == o); }

  const Length& operator*=(float v) {
    if (isCalculated()) {
      ASSERT_NOT_REACHED();
      return *this;
    }

    if (m_isFloat)
      m_floatValue = static_cast<float>(m_floatValue * v);
    else
      m_intValue = static_cast<int>(m_intValue * v);

    return *this;
  }

  inline float value() const { return getFloatValue(); }

  int intValue() const {
    if (isCalculated()) {
      ASSERT_NOT_REACHED();
      return 0;
    }
    return getIntValue();
  }

  float percent() const {
    ASSERT(type() == Percent);
    return getFloatValue();
  }
  PixelsAndPercent pixelsAndPercent() const;

  CalculationValue& calculationValue() const;

  LengthType type() const { return static_cast<LengthType>(m_type); }
  bool quirk() const { return m_quirk; }

  void setQuirk(bool quirk) { m_quirk = quirk; }

  void setValue(LengthType t, int value) {
    m_type = t;
    m_intValue = value;
    m_isFloat = false;
  }

  void setValue(int value) {
    if (isCalculated()) {
      ASSERT_NOT_REACHED();
      return;
    }
    setValue(Fixed, value);
  }

  void setValue(LengthType t, float value) {
    m_type = t;
    m_floatValue = value;
    m_isFloat = true;
  }

  void setValue(LengthType t, LayoutUnit value) {
    m_type = t;
    m_floatValue = value.toFloat();
    m_isFloat = true;
  }

  void setValue(float value) { *this = Length(value, Fixed); }

  bool isMaxSizeNone() const { return type() == MaxSizeNone; }

  // FIXME calc: https://bugs.webkit.org/show_bug.cgi?id=80357. A calculated
  // Length always contains a percentage, and without a maxValue passed to these
  // functions it's impossible to determine the sign or zero-ness. We assume all
  // calc values are positive and non-zero for now.
  bool isZero() const {
    ASSERT(!isMaxSizeNone());
    if (isCalculated())
      return false;

    return m_isFloat ? !m_floatValue : !m_intValue;
  }
  bool isPositive() const {
    if (isMaxSizeNone())
      return false;
    if (isCalculated())
      return true;

    return getFloatValue() > 0;
  }
  bool isNegative() const {
    if (isMaxSizeNone() || isCalculated())
      return false;

    return getFloatValue() < 0;
  }

  bool isAuto() const { return type() == Auto; }
  bool isPercent() const { return type() == Percent || type() == Calculated; }
  bool isFixed() const { return type() == Fixed; }
  bool isIntrinsicOrAuto() const {
    return type() == Auto || isLegacyIntrinsic() || isIntrinsic();
  }
  bool isLegacyIntrinsic() const {
    return type() == Intrinsic || type() == MinIntrinsic;
  }
  bool isIntrinsic() const {
    return type() == MinContent || type() == MaxContent ||
           type() == FillAvailable || type() == FitContent;
  }
  bool isSpecified() const {
    return type() == Fixed || type() == Percent || type() == Calculated;
  }
  bool isSpecifiedOrIntrinsic() const { return isSpecified() || isIntrinsic(); }
  bool isCalculated() const { return type() == Calculated; }
  bool isCalculatedEqual(const Length&) const;
  bool isMinContent() const { return type() == MinContent; }
  bool isMaxContent() const { return type() == MaxContent; }
  bool isFillAvailable() const { return type() == FillAvailable; }
  bool isFitContent() const { return type() == FitContent; }

  Length blend(const Length& from, double progress, ValueRange range) const {
    ASSERT(isSpecified() && from.isSpecified());

    if (progress == 0.0)
      return from;

    if (progress == 1.0)
      return *this;

    if (from.type() == Calculated || type() == Calculated)
      return blendMixedTypes(from, progress, range);

    if (!from.isZero() && !isZero() && from.type() != type())
      return blendMixedTypes(from, progress, range);

    if (from.isZero() && isZero())
      return *this;

    LengthType resultType = type();
    if (isZero())
      resultType = from.type();

    float blendedValue = blink::blend(from.value(), value(), progress);
    if (range == ValueRangeNonNegative)
      blendedValue = clampTo<float>(blendedValue, 0);
    return Length(blendedValue, resultType);
  }

  float getFloatValue() const {
    ASSERT(!isMaxSizeNone());
    return m_isFloat ? m_floatValue : m_intValue;
  }
  float nonNanCalculatedValue(int maxValue) const;

  Length subtractFromOneHundredPercent() const;

 private:
  int getIntValue() const {
    ASSERT(!isMaxSizeNone());
    return m_isFloat ? static_cast<int>(m_floatValue) : m_intValue;
  }

  Length blendMixedTypes(const Length& from, double progress, ValueRange) const;

  int calculationHandle() const {
    ASSERT(isCalculated());
    return getIntValue();
  }
  void incrementCalculatedRef() const;
  void decrementCalculatedRef() const;

  union {
    int m_intValue;
    float m_floatValue;
  };
  bool m_quirk;
  unsigned char m_type;
  bool m_isFloat;
};

}  // namespace blink

#endif  // SKY_ENGINE_PLATFORM_LENGTH_H_