flutter_flutter/sky/engine/platform/animation/TimingFunction.h

/*
 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
 *           (C) 2000 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
 *
 * 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_ANIMATION_TIMINGFUNCTION_H_
#define SKY_ENGINE_PLATFORM_ANIMATION_TIMINGFUNCTION_H_

#include <algorithm>
#include "flutter/sky/engine/platform/animation/AnimationUtilities.h"
#include "flutter/sky/engine/platform/animation/UnitBezier.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"
#include "flutter/sky/engine/wtf/PassOwnPtr.h"
#include "flutter/sky/engine/wtf/PassRefPtr.h"
#include "flutter/sky/engine/wtf/RefCounted.h"
#include "flutter/sky/engine/wtf/StdLibExtras.h"
#include "flutter/sky/engine/wtf/text/StringBuilder.h"
#include "flutter/sky/engine/wtf/text/WTFString.h"

namespace blink {

class PLATFORM_EXPORT TimingFunction : public RefCounted<TimingFunction> {
 public:
  enum Type { LinearFunction, CubicBezierFunction, StepsFunction };

  virtual ~TimingFunction() {}

  Type type() const { return m_type; }

  virtual String toString() const = 0;

  // Evaluates the timing function at the given fraction. The accuracy parameter
  // provides a hint as to the required accuracy and is not guaranteed.
  virtual double evaluate(double fraction, double accuracy) const = 0;

  // This function returns the minimum and maximum values obtainable when
  // calling evaluate();
  virtual void range(double* minValue, double* maxValue) const = 0;

 protected:
  TimingFunction(Type type) : m_type(type) {}

 private:
  Type m_type;
};

class PLATFORM_EXPORT LinearTimingFunction final : public TimingFunction {
 public:
  static LinearTimingFunction* shared() {
    DEFINE_STATIC_REF(LinearTimingFunction, linear,
                      (adoptRef(new LinearTimingFunction())));
    return linear;
  }

  virtual ~LinearTimingFunction() {}

  virtual String toString() const override;

  virtual double evaluate(double fraction, double) const override;

  virtual void range(double* minValue, double* maxValue) const override;

 private:
  LinearTimingFunction() : TimingFunction(LinearFunction) {}
};

class PLATFORM_EXPORT CubicBezierTimingFunction final : public TimingFunction {
 public:
  enum SubType { Ease, EaseIn, EaseOut, EaseInOut, Custom };

  static PassRefPtr<CubicBezierTimingFunction> create(double x1,
                                                      double y1,
                                                      double x2,
                                                      double y2) {
    return adoptRef(new CubicBezierTimingFunction(Custom, x1, y1, x2, y2));
  }

  static CubicBezierTimingFunction* preset(SubType subType) {
    switch (subType) {
      case Ease: {
        DEFINE_STATIC_REF(CubicBezierTimingFunction, ease,
                          (adoptRef(new CubicBezierTimingFunction(
                              Ease, 0.25, 0.1, 0.25, 1.0))));
        return ease;
      }
      case EaseIn: {
        DEFINE_STATIC_REF(CubicBezierTimingFunction, easeIn,
                          (adoptRef(new CubicBezierTimingFunction(
                              EaseIn, 0.42, 0.0, 1.0, 1.0))));
        return easeIn;
      }
      case EaseOut: {
        DEFINE_STATIC_REF(CubicBezierTimingFunction, easeOut,
                          (adoptRef(new CubicBezierTimingFunction(
                              EaseOut, 0.0, 0.0, 0.58, 1.0))));
        return easeOut;
      }
      case EaseInOut: {
        DEFINE_STATIC_REF(CubicBezierTimingFunction, easeInOut,
                          (adoptRef(new CubicBezierTimingFunction(
                              EaseInOut, 0.42, 0.0, 0.58, 1.0))));
        return easeInOut;
      }
      default:
        ASSERT_NOT_REACHED();
        return 0;
    }
  }

  virtual ~CubicBezierTimingFunction() {}

  virtual String toString() const override;

  virtual double evaluate(double fraction, double accuracy) const override;
  virtual void range(double* minValue, double* maxValue) const override;

  double x1() const { return m_x1; }
  double y1() const { return m_y1; }
  double x2() const { return m_x2; }
  double y2() const { return m_y2; }

  SubType subType() const { return m_subType; }

 private:
  explicit CubicBezierTimingFunction(SubType subType,
                                     double x1,
                                     double y1,
                                     double x2,
                                     double y2)
      : TimingFunction(CubicBezierFunction),
        m_x1(x1),
        m_y1(y1),
        m_x2(x2),
        m_y2(y2),
        m_subType(subType) {}

  double m_x1;
  double m_y1;
  double m_x2;
  double m_y2;
  SubType m_subType;
  mutable OwnPtr<UnitBezier> m_bezier;
};

class PLATFORM_EXPORT StepsTimingFunction final : public TimingFunction {
 public:
  enum SubType { Start, End, Middle, Custom };

  enum StepAtPosition { StepAtStart, StepAtMiddle, StepAtEnd };

  static PassRefPtr<StepsTimingFunction> create(int steps,
                                                StepAtPosition stepAtPosition) {
    return adoptRef(new StepsTimingFunction(Custom, steps, stepAtPosition));
  }

  static StepsTimingFunction* preset(SubType subType) {
    switch (subType) {
      case Start: {
        DEFINE_STATIC_REF(
            StepsTimingFunction, start,
            (adoptRef(new StepsTimingFunction(Start, 1, StepAtStart))));
        return start;
      }
      case Middle: {
        DEFINE_STATIC_REF(
            StepsTimingFunction, middle,
            (adoptRef(new StepsTimingFunction(Middle, 1, StepAtMiddle))));
        return middle;
      }
      case End: {
        DEFINE_STATIC_REF(
            StepsTimingFunction, end,
            (adoptRef(new StepsTimingFunction(End, 1, StepAtEnd))));
        return end;
      }
      default:
        ASSERT_NOT_REACHED();
        return 0;
    }
  }

  virtual ~StepsTimingFunction() {}

  virtual String toString() const override;

  virtual double evaluate(double fraction, double) const override;

  virtual void range(double* minValue, double* maxValue) const override;
  int numberOfSteps() const { return m_steps; }
  StepAtPosition stepAtPosition() const { return m_stepAtPosition; }

  SubType subType() const { return m_subType; }

 private:
  StepsTimingFunction(SubType subType, int steps, StepAtPosition stepAtPosition)
      : TimingFunction(StepsFunction),
        m_steps(steps),
        m_stepAtPosition(stepAtPosition),
        m_subType(subType) {}

  int m_steps;
  StepAtPosition m_stepAtPosition;
  SubType m_subType;
};

PLATFORM_EXPORT bool operator==(const LinearTimingFunction&,
                                const TimingFunction&);
PLATFORM_EXPORT bool operator==(const CubicBezierTimingFunction&,
                                const TimingFunction&);
PLATFORM_EXPORT bool operator==(const StepsTimingFunction&,
                                const TimingFunction&);

PLATFORM_EXPORT bool operator==(const TimingFunction&, const TimingFunction&);
PLATFORM_EXPORT bool operator!=(const TimingFunction&, const TimingFunction&);

#define DEFINE_TIMING_FUNCTION_TYPE_CASTS(typeName)                      \
  DEFINE_TYPE_CASTS(typeName##TimingFunction, TimingFunction, value,     \
                    value->type() == TimingFunction::typeName##Function, \
                    value.type() == TimingFunction::typeName##Function)

DEFINE_TIMING_FUNCTION_TYPE_CASTS(Linear);
DEFINE_TIMING_FUNCTION_TYPE_CASTS(CubicBezier);
DEFINE_TIMING_FUNCTION_TYPE_CASTS(Steps);

}  // namespace blink

#endif  // SKY_ENGINE_PLATFORM_ANIMATION_TIMINGFUNCTION_H_