src/cobalt/cssom/percentage_value.h

// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COBALT_CSSOM_PERCENTAGE_VALUE_H_
#define COBALT_CSSOM_PERCENTAGE_VALUE_H_

#include <string>

#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/stringprintf.h"
#include "cobalt/base/polymorphic_equatable.h"
#include "cobalt/cssom/property_value.h"

namespace cobalt {
namespace cssom {

class PropertyValueVisitor;

// Percentage values are always relative to another value, for example a length.
// Each property that allows percentages also defines the value to which
// the percentage refers.
//   https://www.w3.org/TR/css3-values/#percentages
class PercentageValue : public PropertyValue {
 public:
  // A |value| is a normalized factor, where 1 means 100%.
  explicit PercentageValue(float value) : value_(value) {}

  void Accept(PropertyValueVisitor* visitor) OVERRIDE;

  // Returns a normalized factor, where 1 means 100%.
  float value() const { return value_; }

  std::string ToString() const OVERRIDE {
    return base::StringPrintf("%.7g%%", value_ * 100);
  }

  bool operator==(const PercentageValue& other) const {
    return value_ == other.value_;
  }

  DEFINE_POLYMORPHIC_EQUATABLE_TYPE(PercentageValue);

 private:
  ~PercentageValue() OVERRIDE {}

  const float value_;

  DISALLOW_COPY_AND_ASSIGN(PercentageValue);
};

}  // namespace cssom
}  // namespace cobalt

#endif  // COBALT_CSSOM_PERCENTAGE_VALUE_H_