third_party/WebKit/Source/platform/Length.cpp

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller ( mueller@kde.org )
 * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights
 * reserved.
 * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
 *
 * 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.
 *
 */

#include "platform/Length.h"

#include "platform/CalculationValue.h"
#include "platform/animation/AnimationUtilities.h"

using namespace WTF;

namespace blink {

class CalculationValueHandleMap {
  USING_FAST_MALLOC(CalculationValueHandleMap);
  WTF_MAKE_NONCOPYABLE(CalculationValueHandleMap);

 public:
  CalculationValueHandleMap() : m_index(1) {}

  int insert(PassRefPtr<CalculationValue> calcValue) {
    ASSERT(m_index);
    // FIXME calc(): https://bugs.webkit.org/show_bug.cgi?id=80489
    // This monotonically increasing handle generation scheme is potentially
    // wasteful of the handle space. Consider reusing empty handles.
    while (m_map.contains(m_index))
      m_index++;

    m_map.set(m_index, std::move(calcValue));

    return m_index;
  }

  void remove(int index) {
    ASSERT(m_map.contains(index));
    m_map.remove(index);
  }

  CalculationValue& get(int index) {
    ASSERT(m_map.contains(index));
    return *m_map.get(index);
  }

  void decrementRef(int index) {
    ASSERT(m_map.contains(index));
    CalculationValue* value = m_map.get(index);
    if (value->hasOneRef()) {
      // Force the CalculationValue destructor early to avoid a potential
      // recursive call inside HashMap remove().
      m_map.set(index, nullptr);
      m_map.remove(index);
    } else {
      value->deref();
    }
  }

 private:
  int m_index;
  HashMap<int, RefPtr<CalculationValue>> m_map;
};

static CalculationValueHandleMap& calcHandles() {
  DEFINE_STATIC_LOCAL(CalculationValueHandleMap, handleMap, ());
  return handleMap;
}

Length::Length(PassRefPtr<CalculationValue> calc)
    : m_quirk(false), m_type(Calculated), m_isFloat(false) {
  m_intValue = calcHandles().insert(std::move(calc));
}

Length Length::blendMixedTypes(const Length& from,
                               double progress,
                               ValueRange range) const {
  ASSERT(from.isSpecified());
  ASSERT(isSpecified());
  PixelsAndPercent fromPixelsAndPercent = from.getPixelsAndPercent();
  PixelsAndPercent toPixelsAndPercent = getPixelsAndPercent();
  const float pixels = blink::blend(fromPixelsAndPercent.pixels,
                                    toPixelsAndPercent.pixels, progress);
  const float percent = blink::blend(fromPixelsAndPercent.percent,
                                     toPixelsAndPercent.percent, progress);
  return Length(
      CalculationValue::create(PixelsAndPercent(pixels, percent), range));
}

PixelsAndPercent Length::getPixelsAndPercent() const {
  switch (type()) {
    case Fixed:
      return PixelsAndPercent(value(), 0);
    case Percent:
      return PixelsAndPercent(0, value());
    case Calculated:
      return getCalculationValue().getPixelsAndPercent();
    default:
      ASSERT_NOT_REACHED();
      return PixelsAndPercent(0, 0);
  }
}

Length Length::subtractFromOneHundredPercent() const {
  PixelsAndPercent result = getPixelsAndPercent();
  result.pixels = -result.pixels;
  result.percent = 100 - result.percent;
  if (result.pixels && result.percent)
    return Length(CalculationValue::create(result, ValueRangeAll));
  if (result.percent)
    return Length(result.percent, Percent);
  return Length(result.pixels, Fixed);
}

Length Length::zoom(double factor) const {
  switch (type()) {
    case Fixed:
      return Length(getFloatValue() * factor, Fixed);
    case Calculated: {
      PixelsAndPercent result = getPixelsAndPercent();
      result.pixels *= factor;
      return Length(CalculationValue::create(
          result, getCalculationValue().getValueRange()));
    }
    default:
      return *this;
  }
}

CalculationValue& Length::getCalculationValue() const {
  ASSERT(isCalculated());
  return calcHandles().get(calculationHandle());
}

void Length::incrementCalculatedRef() const {
  ASSERT(isCalculated());
  getCalculationValue().ref();
}

void Length::decrementCalculatedRef() const {
  ASSERT(isCalculated());
  calcHandles().decrementRef(calculationHandle());
}

float Length::nonNanCalculatedValue(LayoutUnit maxValue) const {
  ASSERT(isCalculated());
  float result = getCalculationValue().evaluate(maxValue.toFloat());
  if (std::isnan(result))
    return 0;
  return result;
}

bool Length::isCalculatedEqual(const Length& o) const {
  return isCalculated() &&
         (&getCalculationValue() == &o.getCalculationValue() ||
          getCalculationValue() == o.getCalculationValue());
}

struct SameSizeAsLength {
  int32_t value;
  int32_t metaData;
};
static_assert(sizeof(Length) == sizeof(SameSizeAsLength),
              "length should stay small");

}  // namespace blink