Add Doxygen comments to RationalTime (#1765)

Signed-off-by: Darby Johnston <[email protected]>

src/opentime/rationalTime.h

@@ -12,13 +12,17 @@
 
 namespace opentime { namespace OPENTIME_VERSION {
 
+/// @brief This enumeration provides options for drop frame timecode.
 enum IsDropFrameRate : int
 {
     InferFromRate = -1,
     ForceNo       = 0,
     ForceYes      = 1,
 };
 
+/// @brief Returns the absolute value.
+///
+/// \todo Document why this function is used instead of "std::fabs()".
 constexpr double
 fabs(double val) noexcept
 {
@@ -31,77 +35,104 @@ fabs(double val) noexcept
     return bits.f;
 }
 
+/// @brief This class represents a measure of time defined by a value and rate.
 class RationalTime
 {
 public:
+    /// @brief Construct a new time with an optional value and rate.
     explicit constexpr RationalTime(double value = 0, double rate = 1) noexcept
         : _value{ value }
         , _rate{ rate }
     {}
 
+    /// @brief Returns true if the time is invalid.
+    ///
+    /// The time is considered invalid if the value or rate are a NaN value,
+    /// or if the rate is less than or equal to zero.
     bool is_invalid_time() const noexcept
     {
         return (std::isnan(_rate) || std::isnan(_value)) ? true : (_rate <= 0);
     }
 
+    /// @brief Returns the time value.
     constexpr double value() const noexcept { return _value; }
 
+    /// @brief Returns the time rate.
     constexpr double rate() const noexcept { return _rate; }
 
+    /// @brief Returns the time converted to a new rate.
     constexpr RationalTime rescaled_to(double new_rate) const noexcept
     {
         return RationalTime{ value_rescaled_to(new_rate), new_rate };
     }
 
+    /// @brief Returns the time converted to a new rate.
     constexpr RationalTime rescaled_to(RationalTime rt) const noexcept
     {
         return RationalTime{ value_rescaled_to(rt._rate), rt._rate };
     }
 
+    /// @brief Returns the time value converted to a new rate.
     constexpr double value_rescaled_to(double new_rate) const noexcept
     {
         return new_rate == _rate ? _value : (_value * new_rate) / _rate;
     }
 
+    /// @brief Returns the time value converted to a new rate.
     constexpr double value_rescaled_to(RationalTime rt) const noexcept
     {
         return value_rescaled_to(rt._rate);
     }
 
+    /// @brief Returns whether time is almost equal to another time.
+    ///
+    /// @param other The other time for comparison.
+    /// @param delta The tolerance used for the comparison.
     constexpr bool
     almost_equal(RationalTime other, double delta = 0) const noexcept
     {
         return fabs(value_rescaled_to(other._rate) - other._value) <= delta;
     }
 
-    // Return whether the value and rate are equal to another RationalTime.
-    // This is different from the operator "==" that rescales the time before
-    // comparison.
+    /// @brief Returns whether the value and rate are equal to another time.
+    ///
+    /// This is different from the operator "==" that rescales the time before
+    /// comparison.
     constexpr bool strictly_equal(RationalTime other) const noexcept
     {
         return _value == other._value && _rate == other._rate;
     }
 
-    // Return a RationalTime with the largest integer value not greater than
-    // this value.
+    /// @brief Returns a time with the largest integer value not greater than
+    /// this value.
     RationalTime floor() const
     {
         return RationalTime{ std::floor(_value), _rate };
     }
 
-    // Return a RationalTime with the smallest integer value not less than
-    // this value.
+    /// @brief Returns a time with the smallest integer value not less than
+    /// this value.
     RationalTime ceil() const
     {
         return RationalTime{ std::ceil(_value), _rate };
     }
 
-    // Return a RationalTime with the nearest integer value to this value.
+    /// @brief Returns a time with the nearest integer value to this value.
     RationalTime round() const
     {
         return RationalTime{ std::round(_value), _rate };
     }
 
+    /// @brief Compute the duration of samples from first to last (excluding
+    /// last).
+    ///
+    /// Note that this is not the same as distance.
+    ///
+    /// For example, the duration of a clip from frame 10 to frame 15 is 5
+    /// frames. The result will be in the rate of start time.
+    ///
+    /// @param start_time The start time.
+    /// @param end_time_exclusive The exclusive end time.
     static constexpr RationalTime duration_from_start_end_time(
         RationalTime start_time,
         RationalTime end_time_exclusive) noexcept
@@ -116,6 +147,16 @@ class RationalTime
                                    start_time._rate };
     }
 
+    /// @brief Compute the duration of samples from first to last (including
+    /// last).
+    ///
+    /// Note that this is not the same as distance.
+    ///
+    /// For example, the duration of a clip from frame 10 to frame 15 is 6
+    /// frames. Result will be in the rate of start time.
+    ///
+    /// @param start_time The start time.
+    /// @param end_time_exclusive The inclusive end time.
     static constexpr RationalTime duration_from_start_end_time_inclusive(
         RationalTime start_time,
         RationalTime end_time_inclusive) noexcept
@@ -130,80 +171,112 @@ class RationalTime
                                    start_time._rate };
     }
 
+    /// @brief Returns true if the rate is valid for use with timecode.
     static bool is_valid_timecode_rate(double rate);
 
+    /// @brief Returns the first valid timecode rate that has the least
+    /// difference from rate.
     static double nearest_valid_timecode_rate(double rate);
 
+    /// @brief Convert a frame number and rate into a time.
     static constexpr RationalTime
     from_frames(double frame, double rate) noexcept
     {
         return RationalTime{ double(int(frame)), rate };
     }
 
+    /// @brief Convert a value in seconds and rate into a time.
     static constexpr RationalTime
     from_seconds(double seconds, double rate) noexcept
     {
         return RationalTime{ seconds, 1 }.rescaled_to(rate);
     }
 
+    /// @brief Convert a value in seconds into a time.
     static constexpr RationalTime from_seconds(double seconds) noexcept
     {
         return RationalTime{ seconds, 1 };
     }
 
+    /// @brief Convert a timecode string ("HH:MM:SS;FRAME") into a time.
+    ///
+    /// @param timecode The timecode string.
+    /// @param rate The timecode rate.
+    /// @param error_status Optional error status.
     static RationalTime from_timecode(
         std::string const& timecode,
         double             rate,
         ErrorStatus*       error_status = nullptr);
 
-    // parse a string in the form
-    // hours:minutes:seconds
-    // which may have a leading negative sign. seconds may have up to
-    // microsecond precision.
+    /// @brief Parse a string in the form "hours:minutes:seconds".
+    ///
+    /// The string may have a leading negative sign.
+    ///
+    /// Seconds may have up to microsecond precision.
+    ///
+    /// @param time_string The time string.
+    /// @param rate The time rate.
+    /// @param error_status Optional error status.
     static RationalTime from_time_string(
         std::string const& time_string,
         double             rate,
         ErrorStatus*       error_status = nullptr);
 
+    /// @brief Returns the frame number based on the current rate.
     constexpr int to_frames() const noexcept { return int(_value); }
 
+    /// @brief Returns the frame number based on the given rate.
     constexpr int to_frames(double rate) const noexcept
     {
         return int(value_rescaled_to(rate));
     }
 
+    /// @brief Returns the value in seconds.
     constexpr double to_seconds() const noexcept
     {
         return value_rescaled_to(1);
     }
 
+    /// @brief Convert to timecode (e.g., "HH:MM:SS;FRAME").
+    ///
+    /// @param rate The timecode rate.
+    /// @param drop_frame Whether to use drop frame timecode.
+    /// @param error_status Optional error status.
     std::string to_timecode(
         double          rate,
         IsDropFrameRate drop_frame,
         ErrorStatus*    error_status = nullptr) const;
 
+    /// @brief Convert to timecode (e.g., "HH:MM:SS;FRAME").
     std::string to_timecode(ErrorStatus* error_status = nullptr) const
     {
         return to_timecode(_rate, IsDropFrameRate::InferFromRate, error_status);
     }
 
+    /// @brief Convert to the nearest timecode (e.g., "HH:MM:SS;FRAME").
+    ///
+    /// @param rate The timecode rate.
+    /// @param drop_frame Whether to use drop frame timecode.
+    /// @param error_status Optional error status.
     std::string to_nearest_timecode(
         double          rate,
         IsDropFrameRate drop_frame,
         ErrorStatus*    error_status = nullptr) const;
 
+    /// @brief Convert to the nearest timecode (e.g., "HH:MM:SS;FRAME").
     std::string to_nearest_timecode(ErrorStatus* error_status = nullptr) const
     {
         return to_nearest_timecode(_rate, IsDropFrameRate::InferFromRate, error_status);
     }
 
-
-    // produce a string in the form
-    // hours:minutes:seconds
-    // which may have a leading negative sign. seconds may have up to
-    // microsecond precision.
+    /// @brief Return a string in the form "hours:minutes:seconds".
+    ///
+    /// Seconds may have up to microsecond precision.
+    ///
+    /// @return The time string, which may have a leading negative sign.
     std::string to_time_string() const;
 
+    /// @brief Add a time to this time.
     constexpr RationalTime const& operator+=(RationalTime other) noexcept
     {
         if (_rate < other._rate)
@@ -218,6 +291,7 @@ class RationalTime
         return *this;
     }
 
+    /// @brief Subtract a time from this time.
     constexpr RationalTime const& operator-=(RationalTime other) noexcept
     {
         if (_rate < other._rate)
@@ -232,6 +306,7 @@ class RationalTime
         return *this;
     }
 
+    /// @brief Return the addition of two times.
     friend constexpr RationalTime
     operator+(RationalTime lhs, RationalTime rhs) noexcept
     {
@@ -244,6 +319,7 @@ class RationalTime
                                    lhs._rate };
     }
 
+    /// @brief Return the subtraction of two times.
     friend constexpr RationalTime
     operator-(RationalTime lhs, RationalTime rhs) noexcept
     {
@@ -256,39 +332,60 @@ class RationalTime
                                    lhs._rate };
     }
 
+    /// @brief Return the negative of this time.
     friend constexpr RationalTime operator-(RationalTime lhs) noexcept
     {
         return RationalTime{ -lhs._value, lhs._rate };
     }
 
+    /// @brief Return whether a time is greater than another time.
     friend constexpr bool operator>(RationalTime lhs, RationalTime rhs) noexcept
     {
         return (lhs._value / lhs._rate) > (rhs._value / rhs._rate);
     }
 
+    /// @brief Return whether a time is greater or equal to another time.
     friend constexpr bool
     operator>=(RationalTime lhs, RationalTime rhs) noexcept
     {
         return (lhs._value / lhs._rate) >= (rhs._value / rhs._rate);
     }
 
+    /// @brief Return whether a time is less than another time.
     friend constexpr bool operator<(RationalTime lhs, RationalTime rhs) noexcept
     {
         return !(lhs >= rhs);
     }
 
+    /// @brief Return whether a time is less than or equal to another time.
     friend constexpr bool
     operator<=(RationalTime lhs, RationalTime rhs) noexcept
     {
         return !(lhs > rhs);
     }
 
+    /// @brief Return whether two times are equal.
+    ///
+    /// Note that the right hand side time is rescaled to the rate of the
+    /// left hand side time. To compare two times without scaling, use
+    /// strictly_equal().
+    ///
+    /// @param lhs Left hand side time.
+    /// @param lhs Right hand side time.
     friend constexpr bool
     operator==(RationalTime lhs, RationalTime rhs) noexcept
     {
         return lhs.value_rescaled_to(rhs._rate) == rhs._value;
     }
 
+    /// @brief Return whether two times are not equal.
+    ///
+    /// Note that the right hand side time is rescaled to the rate of the
+    /// left hand side time. To compare two times without scaling, use
+    /// strictly_equal().
+    ///
+    /// @param lhs Left hand side time.
+    /// @param lhs Right hand side time.
     friend constexpr bool
     operator!=(RationalTime lhs, RationalTime rhs) noexcept
     {