/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* representation of a value for a SMIL-animated CSS property */

#ifndef NS_SMILCSSVALUETYPE_H_
#define NS_SMILCSSVALUETYPE_H_

#include "nsISMILType.h"
#include "nsCSSProperty.h"
#include "nscore.h" // For NS_OVERRIDE

class nsAString;

namespace mozilla {
namespace dom {
class Element;
} // namespace dom
} // namespace mozilla

/*
 * nsSMILCSSValueType: Represents a SMIL-animated CSS value.
 */
class nsSMILCSSValueType : public nsISMILType
{
public:
  typedef mozilla::dom::Element Element;

  // Singleton for nsSMILValue objects to hold onto.
  static nsSMILCSSValueType sSingleton;

protected:
  // nsISMILType Methods
  // -------------------
  NS_OVERRIDE virtual void     Init(nsSMILValue& aValue) const;
  NS_OVERRIDE virtual void     Destroy(nsSMILValue&) const;
  NS_OVERRIDE virtual nsresult Assign(nsSMILValue& aDest,
                                      const nsSMILValue& aSrc) const;
  NS_OVERRIDE virtual bool     IsEqual(const nsSMILValue& aLeft,
                                       const nsSMILValue& aRight) const;
  NS_OVERRIDE virtual nsresult Add(nsSMILValue& aDest,
                                   const nsSMILValue& aValueToAdd,
                                   PRUint32 aCount) const;
  NS_OVERRIDE virtual nsresult ComputeDistance(const nsSMILValue& aFrom,
                                               const nsSMILValue& aTo,
                                               double& aDistance) const;
  NS_OVERRIDE virtual nsresult Interpolate(const nsSMILValue& aStartVal,
                                           const nsSMILValue& aEndVal,
                                           double aUnitDistance,
                                           nsSMILValue& aResult) const;

public:
  // Helper Methods
  // --------------
  /**
   * Sets up the given nsSMILValue to represent the given string value.  The
   * string is interpreted as a value for the given property on the given
   * element.
   *
   * On failure, this method leaves aValue.mType == nsSMILNullType::sSingleton.
   * Otherwise, this method leaves aValue.mType == this class's singleton.
   *
   * @param       aPropID         The property for which we're parsing a value.
   * @param       aTargetElement  The target element to whom the property/value
   *                              setting applies.
   * @param       aString         The string to be parsed as a CSS value.
   * @param [out] aValue          The nsSMILValue to be populated. Should
   *                              initially be null-typed.
   * @param [out] aIsContextSensitive Set to true if |aString| may produce
   *                                  a different |aValue| depending on other
   *                                  CSS properties on |aTargetElement|
   *                                  or its ancestors (e.g. 'inherit).
   *                                  false otherwise. May be nsnull.
   *                                  Not set if the method fails.
   * @pre  aValue.IsNull()
   * @post aValue.IsNull() || aValue.mType == nsSMILCSSValueType::sSingleton
   */
  static void ValueFromString(nsCSSProperty aPropID,
                              Element* aTargetElement,
                              const nsAString& aString,
                              nsSMILValue& aValue,
                              bool* aIsContextSensitive);

  /**
   * Creates a string representation of the given nsSMILValue.
   *
   * Note: aValue is expected to be of this type (that is, it's expected to
   * have been initialized by nsSMILCSSValueType::sSingleton).  If aValue is a
   * freshly-initialized value, this method will succeed, though the resulting
   * string will be empty.
   *
   * @param       aValue   The nsSMILValue to be converted into a string.
   * @param [out] aString  The string to be populated with the given value.
   * @return               true on success, false on failure.
   */
  static bool ValueToString(const nsSMILValue& aValue, nsAString& aString);

private:
  // Private constructor & destructor: prevent instances beyond my singleton,
  // and prevent others from deleting my singleton.
  nsSMILCSSValueType()  {}
  ~nsSMILCSSValueType() {}
};

#endif // NS_SMILCSSVALUETYPE_H_
