Simple Stopwatch Class

[jmcilhinney]

Public Class Stopwatch
 
    Private startTime As Date
    Private m_Elapsed As TimeSpan
    Private m_Running As Boolean
 
    ''' <summary>
    ''' The amount of time that has elapsed.
    ''' </summary>
    Public ReadOnly Property Elapsed() As TimeSpan
        Get
            Dim time As TimeSpan = Me.m_Elapsed
 
            If Me.m_Running Then
                time = time.Add(Date.Now.Subtract(Me.startTime))
            End If
 
            Return time
        End Get
    End Property
 
    ''' <summary>
    ''' Indicates whether the stopwatch is currently timing or not.
    ''' </summary>
    Public ReadOnly Property Running() As Boolean
        Get
            Return Me.m_Running
        End Get
    End Property
 
    ''' <summary>
    ''' Creates a new Stopwatch object.
    ''' </summary>
    Public Sub New()
        ' Initialise with no time elapsed.
        Me.m_Elapsed = TimeSpan.Zero
        Me.m_Running = False
    End Sub
 
    ''' <summary>
    ''' Starts the stopwatch.
    ''' </summary>
    ''' <returns>
    ''' True if the stopwatch was started; False if the stopwatch was already running.
    ''' </returns>
    Public Function Start() As Boolean
        Dim result As Boolean = Not Me.m_Running
 
        If result Then
            Me.startTime = Date.Now
            Me.m_Running = True
        End If
 
        Return result
    End Function
 
    ''' <summary>
    ''' Stops the stopwatch.
    ''' </summary>
    ''' <returns>
    ''' True if the stopwatch was stopped; False if the stopwatch was not running.
    ''' </returns>
    Public Function [Stop]() As Boolean
        Dim result As Boolean = Me.m_Running
 
        If result Then
            Me.m_Elapsed = Me.m_Elapsed.Add(Date.Now.Subtract(Me.startTime))
            Me.m_Running = False
        End If
 
        Return result
    End Function
 
    ''' <summary>
    ''' Resets the elapsed time to zero.
    ''' </summary>
    Public Sub Reset()
        ' Set the start time in case the stopwatch is running.
        Me.startTime = Date.Now
        Me.m_Elapsed = TimeSpan.Zero
    End Sub
 
End Class