Timer (Component) der synchron zur Systemuhr tickt

    • VB.NET

    Es gibt 1 Antwort in diesem Thema. Der letzte Beitrag () ist von ErfinderDesRades.

      Timer (Component) der synchron zur Systemuhr tickt

      Der Titel sagt eigentlich alles.
      Dieser Timer tickt halbwegs synchron zur Systemuhr, und zwar zur jeden vollen Sekunde.

      VB.NET-Quellcode

      1. Imports System.ComponentModel
      3. ''' <summary>
      4. ''' Synchronized to the system clock, ticks every full second.
      5. ''' </summary>
      6. <ToolboxItem(True)>
      7. <ToolboxBitmap(GetType(Timer), "System.Windows.Forms.Timer.bmp")>
      8. Public Class SystemClockTimer
      9. Inherits Timer
      11. ''' <summary>
      12. ''' Will be calculated automatically.
      13. ''' </summary>
      14. ''' <returns>
      15. ''' Calculated milliseconds as Integer.
      16. ''' </returns>
      17. <Browsable(False)>
      18. <DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)>
      19. <EditorBrowsable(EditorBrowsableState.Never)>
      20. Public Shadows ReadOnly Property Interval() As Integer
      21. Get
      22. Return Math.Max(1, 1000 - Date.Now.Millisecond)
      23. End Get
      24. End Property
      26. Public Overloads Property Enabled() As Boolean
      27. Get
      28. Return MyBase.Enabled
      29. End Get
      30. Set(value As Boolean)
      31. MyBase.Enabled = value
      32. If value Then
      33. MyBase.Interval = Interval
      34. MyBase.Start()
      35. Else
      36. MyBase.Stop()
      37. End If
      38. End Set
      39. End Property
      41. Public Shadows Event Tick(sender As Object, e As SystemClockTimerEventArgs)
      43. Private Sub MyBase_Tick(sender As Object, e As EventArgs) Handles MyBase.Tick
      44. RaiseEvent Tick(sender, New SystemClockTimerEventArgs())
      45. MyBase.Interval = Interval
      46. End Sub
      48. Public Overloads Sub Start()
      49. Enabled = True
      50. End Sub
      52. Public Overloads Sub [Stop]()
      53. Enabled = False
      54. End Sub
      56. End Class
      58. Public Class SystemClockTimerEventArgs
      59. Inherits EventArgs
      61. Public ReadOnly Property Now As Date
      63. Sub New()
      64. Now = Date.Now
      65. End Sub
      67. End Class


      Anwendungsbeispiel:

      VB.NET-Quellcode

      1. Private Sub SystemClockTimer1_Tick(sender As Object, e As SystemClockTimerEventArgs) Handles SystemClockTimer1.Tick
      2. LabelClock.Text = e.Now.ToLocalTime.ToLongTimeString
      3. End Sub

      Vereinfachungen:

      VB.NET-Quellcode

      1. Imports System.ComponentModel
      3. ''' <summary>Synchronized to the system clock, ticks every full second.</summary>
      4. <ToolboxItem(True)>
      5. <ToolboxBitmap(GetType(Timer), "System.Windows.Forms.Timer.bmp")>
      6. Public Class SystemClockTimer : Inherits Timer
      8. ''' <summary>calculated automatically in milliseconds, Attributes hide it to Users</summary>
      9. <Browsable(False)>
      10. <DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)>
      11. <EditorBrowsable(EditorBrowsableState.Never)>
      12. Public Shadows ReadOnly Property Interval() As Integer
      13. Get
      14. Return Math.Max(1, 1000 - Date.Now.Millisecond)
      15. End Get
      16. End Property
      18. Public Overrides Property Enabled() As Boolean
      19. Get
      20. Return MyBase.Enabled
      21. End Get
      22. Set(value As Boolean)
      23. If value = MyBase.Enabled Then Return
      24. If value Then MyBase.Interval = Interval
      25. MyBase.Enabled = value
      26. End Set
      27. End Property
      29. Protected Overrides Sub OnTick(e As EventArgs)
      30. MyBase.OnTick(e)
      31. MyBase.Interval = Interval
      32. End Sub
      34. End Class
      Statt Shadowing ist Overriding anwendbar, insbesondere auch beim Event (Event/OnEvent-Override - Pattern). Dadurch kann das bestehende Event weiter-benutzt werden - ein eigenes braucht nicht neu erfunden zu werden.

      Aufruf

      VB.NET-Quellcode

      1. Private Sub SystemClockTimer1_Tick(sender As Object, e As EventArgs) Handles SystemClockTimer1.Tick
      2. LabelClock.Text = Date.Now.ToLocalTime.ToLongTimeString
      3. End Sub

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