third_party/blink/renderer/platform/geometry/calculation_value.h

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_GEOMETRY_CALCULATION_VALUE_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_GEOMETRY_CALCULATION_VALUE_H_

#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/platform/geometry/length.h"
#include "third_party/blink/renderer/platform/geometry/length_functions.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/ref_counted.h"

namespace blink {

class CalculationExpressionNode;

// TODO(xiaochengh): Make |CalculationValue| immutable, namely, accessible only
// via const pointers and references.
class PLATFORM_EXPORT CalculationValue : public RefCounted<CalculationValue> {
  USING_FAST_MALLOC(CalculationValue);

 public:
  static scoped_refptr<CalculationValue> Create(PixelsAndPercent value,
                                                ValueRange range) {
    return base::AdoptRef(new CalculationValue(value, range));
  }

  // If |expression| simply wraps a |PixelsAndPercent| value, this function
  // takes that value directly and discards |expression|.
  static scoped_refptr<CalculationValue> CreateSimplified(
      scoped_refptr<const CalculationExpressionNode> expression,
      ValueRange range);

  ~CalculationValue();

  float Evaluate(float max_value) const;
  bool operator==(const CalculationValue& o) const;
  bool IsExpression() const { return is_expression_; }
  bool IsNonNegative() const { return is_non_negative_; }
  ValueRange GetValueRange() const {
    return is_non_negative_ ? kValueRangeNonNegative : kValueRangeAll;
  }

  float Pixels() const {
    DCHECK(!IsExpression());
    return data_.value.pixels;
  }
  float Percent() const {
    DCHECK(!IsExpression());
    return data_.value.percent;
  }
  PixelsAndPercent GetPixelsAndPercent() const {
    DCHECK(!IsExpression());
    return data_.value;
  }

  // If |this| is an expression, returns the underlying expression. Otherwise,
  // creates one from the underlying |PixelsAndPercent| value.
  scoped_refptr<const CalculationExpressionNode> GetOrCreateExpression() const;

  scoped_refptr<CalculationValue> Blend(const CalculationValue& from,
                                        double progress,
                                        ValueRange) const;
  scoped_refptr<CalculationValue> SubtractFromOneHundredPercent() const;
  scoped_refptr<CalculationValue> Zoom(double factor) const;

 private:
  CalculationValue(PixelsAndPercent value, ValueRange range)
      : data_(value),
        is_expression_(false),
        is_non_negative_(range == kValueRangeNonNegative) {}

  CalculationValue(scoped_refptr<const CalculationExpressionNode> expression,
                   ValueRange range);

  union DataUnion {
    explicit DataUnion(PixelsAndPercent value) : value(value) {}
    explicit DataUnion(
        scoped_refptr<const CalculationExpressionNode> expression);
    ~DataUnion();

    PixelsAndPercent value;
    scoped_refptr<const CalculationExpressionNode> expression;
  } data_;
  unsigned is_expression_ : 1;
  unsigned is_non_negative_ : 1;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_GEOMETRY_CALCULATION_VALUE_H_