dom/smil/nsSMILTimeValue.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef NS_SMILTIMEVALUE_H_
   7 #define NS_SMILTIMEVALUE_H_
   8
   9 #include "nsSMILTypes.h"
  10 #include "nsDebug.h"
  11
  12 /*----------------------------------------------------------------------
  13  * nsSMILTimeValue class
  14  *
  15  * A tri-state time value.
  16  *
  17  * First a quick overview of the SMIL time data types:
  18  *
  19  * nsSMILTime          -- a timestamp in milliseconds.
  20  * nsSMILTimeValue     -- (this class) a timestamp that can take the additional
  21  *                        states 'indefinite' and 'unresolved'
  22  * nsSMILInstanceTime  -- an nsSMILTimeValue used for constructing intervals. It
  23  *                        contains additional fields to govern reset behavior
  24  *                        and track timing dependencies (e.g. syncbase timing).
  25  * nsSMILInterval      -- a pair of nsSMILInstanceTimes that defines a begin and
  26  *                        an end time for animation.
  27  * nsSMILTimeValueSpec -- a component of a begin or end attribute, such as the
  28  *                        '5s' or 'a.end+2m' in begin="5s; a.end+2m". Acts as
  29  *                        a broker between an nsSMILTimedElement and its
  30  *                        nsSMILInstanceTimes by generating new instance times
  31  *                        and handling changes to existing times.
  32  *
  33  * Objects of this class may be in one of three states:
  34  *
  35  * 1) The time is resolved and has a definite millisecond value
  36  * 2) The time is resolved and indefinite
  37  * 3) The time is unresolved
  38  *
  39  * In summary:
  40  *
  41  * State      | GetMillis       | IsDefinite | IsIndefinite | IsResolved
  42  * -----------+-----------------+------------+--------------+------------
  43  * Definite   | nsSMILTimeValue | true       | false        | true
  44  * -----------+-----------------+------------+--------------+------------
  45  * Indefinite | --              | false      | true         | true
  46  * -----------+-----------------+------------+--------------+------------
  47  * Unresolved | --              | false      | false        | false
  48  *
  49  */
  50
  51 class nsSMILTimeValue
  52 {
  53 public:
  54   // Creates an unresolved time value
  55   nsSMILTimeValue()
  56   : mMilliseconds(kUnresolvedMillis),
  57     mState(STATE_UNRESOLVED)
  58   { }
  59
  60   // Creates a resolved time value
  61   explicit nsSMILTimeValue(nsSMILTime aMillis)
  62   : mMilliseconds(aMillis),
  63     mState(STATE_DEFINITE)
  64   { }
  65
  66   // Named constructor to create an indefinite time value
  67   static nsSMILTimeValue Indefinite()
  68   {
  69     nsSMILTimeValue value;
  70     value.SetIndefinite();
  71     return value;
  72   }
  73
  74   bool IsIndefinite() const { return mState == STATE_INDEFINITE; }
  75   void SetIndefinite()
  76   {
  77     mState = STATE_INDEFINITE;
  78     mMilliseconds = kUnresolvedMillis;
  79   }
  80
  81   bool IsResolved() const { return mState != STATE_UNRESOLVED; }
  82   void SetUnresolved()
  83   {
  84     mState = STATE_UNRESOLVED;
  85     mMilliseconds = kUnresolvedMillis;
  86   }
  87
  88   bool IsDefinite() const { return mState == STATE_DEFINITE; }
  89   nsSMILTime GetMillis() const
  90   {
  91     NS_ABORT_IF_FALSE(mState == STATE_DEFINITE,
  92        "GetMillis() called for unresolved or indefinite time");
  93
  94     return mState == STATE_DEFINITE ? mMilliseconds : kUnresolvedMillis;
  95   }
  96
  97   void SetMillis(nsSMILTime aMillis)
  98   {
  99     mState = STATE_DEFINITE;
 100     mMilliseconds = aMillis;
 101   }
 102
 103   int8_t CompareTo(const nsSMILTimeValue& aOther) const;
 104
 105   bool operator==(const nsSMILTimeValue& aOther) const
 106   { return CompareTo(aOther) == 0; }
 107
 108   bool operator!=(const nsSMILTimeValue& aOther) const
 109   { return CompareTo(aOther) != 0; }
 110
 111   bool operator<(const nsSMILTimeValue& aOther) const
 112   { return CompareTo(aOther) < 0; }
 113
 114   bool operator>(const nsSMILTimeValue& aOther) const
 115   { return CompareTo(aOther) > 0; }
 116
 117   bool operator<=(const nsSMILTimeValue& aOther) const
 118   { return CompareTo(aOther) <= 0; }
 119
 120   bool operator>=(const nsSMILTimeValue& aOther) const
 121   { return CompareTo(aOther) >= 0; }
 122
 123 private:
 124   static nsSMILTime kUnresolvedMillis;
 125
 126   nsSMILTime mMilliseconds;
 127   enum {
 128     STATE_DEFINITE,
 129     STATE_INDEFINITE,
 130     STATE_UNRESOLVED
 131   } mState;
 132 };
 133
 134 #endif // NS_SMILTIMEVALUE_H_