Timer.SynchronizingObject Property
Important
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Gets or sets the object used to marshal event-handler calls that are issued when an interval has elapsed.
public:
property System::ComponentModel::ISynchronizeInvoke ^ SynchronizingObject { System::ComponentModel::ISynchronizeInvoke ^ get(); void set(System::ComponentModel::ISynchronizeInvoke ^ value); };
public System.ComponentModel.ISynchronizeInvoke SynchronizingObject { get; set; }
public System.ComponentModel.ISynchronizeInvoke? SynchronizingObject { get; set; }
[System.Timers.TimersDescription("TimerSynchronizingObject")]
public System.ComponentModel.ISynchronizeInvoke SynchronizingObject { get; set; }
[System.Timers.TimersDescription("TimerSynchronizingObject")]
[System.ComponentModel.Browsable(false)]
public System.ComponentModel.ISynchronizeInvoke SynchronizingObject { get; set; }
member this.SynchronizingObject : System.ComponentModel.ISynchronizeInvoke with get, set
[<System.Timers.TimersDescription("TimerSynchronizingObject")>]
member this.SynchronizingObject : System.ComponentModel.ISynchronizeInvoke with get, set
[<System.Timers.TimersDescription("TimerSynchronizingObject")>]
[<System.ComponentModel.Browsable(false)>]
member this.SynchronizingObject : System.ComponentModel.ISynchronizeInvoke with get, set
Public Property SynchronizingObject As ISynchronizeInvoke
The ISynchronizeInvoke representing the object used to marshal the event-handler calls that are issued when an interval has elapsed. The default is null
.
- Attributes
The following example is a Windows Forms app that serves as a very simple text file editor. When the text in the text box has not been saved, the app asks the user at one-minute intervals whether they want to save the contents of the text box. To do this, the Interval property is set to one minute (60,000 milliseconds), and the SynchronizingObject property is set to the Form object.
using System;
using System.IO;
using Timers = System.Timers;
using System.Windows.Forms;
public partial class Form1 : Form
{
Timers.Timer timer = null;
StreamWriter sw = null;
bool hasChanged = false;
bool dialogIsOpen = false;
int elapsedMinutes = 0;
// Cache the text box cache internally without saving it.
String txt = "";
public Form1()
{
InitializeComponent();
this.Text = "Quick Text Editor";
button1.Text = "Save";
textBox1.Multiline = true;
// Configure the SaveFile dialog
saveFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
saveFileDialog1.RestoreDirectory = true;
// Create a timer with a 1-minute interval
timer = new Timers.Timer(60000);
// Define the event handler
timer.Elapsed += this.PromptForSave;
// Synchronize the timer with the text box
timer.SynchronizingObject = this;
// Start the timer
timer.AutoReset = true;
}
private void PromptForSave(Object source, Timers.ElapsedEventArgs e)
{
if (hasChanged & (!dialogIsOpen)) {
elapsedMinutes++;
dialogIsOpen = true;
if (MessageBox.Show(String.Format("{0} minutes have elapsed since the text was saved. Save it now? ",
elapsedMinutes), "Save Text",
MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question) == DialogResult.Yes)
{
button1_Click(this, EventArgs.Empty);
dialogIsOpen = false;
}
}
}
private void button1_Click(Object sender, EventArgs e)
{
if (String.IsNullOrEmpty(saveFileDialog1.FileName)) {
if (saveFileDialog1.ShowDialog() == DialogResult.OK)
sw = new StreamWriter(saveFileDialog1.FileName, false);
}
txt = textBox1.Text;
hasChanged = false;
timer.Stop();
}
private void form1_FormClosing(Object sender, FormClosingEventArgs e)
{
if (sw != null) {
sw.Write(txt);
sw.Close();
}
}
private void textBox1_TextChanged(Object sender, EventArgs e)
{
hasChanged = true;
timer.Start();
}
}
Imports System.IO
Imports System.Timers
Public Class Form1
' Create the timer to fire at a 60-second interval.
Dim WithEvents timer As New System.Timers.Timer(60000)
Dim sw As StreamWriter
Dim hasChanged As Boolean
Dim dialogIsOpen As Boolean = False
Dim elapsedMinutes As Integer = 0
' Cache the text box internally without saving it.
Dim txt As String = ""
Public Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
Me.Text = "Quick Text Editor"
Button1.Text = "Save"
TextBox1.Multiline = True
' Configure the SaveFile dialog
SaveFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
SaveFileDialog1.RestoreDirectory = True
' Create a timer with a 1-minute interval
timer = New Timer(2000)
' Synchronize the timer with the text box
timer.SynchronizingObject = Me
' Start the timer
timer.AutoReset = True
End Sub
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
hasChanged = True
timer.Start()
End Sub
Friend Sub PromptForSave(sender As Object, e As ElapsedEventArgs) _
Handles timer.Elapsed
If hasChanged And Not dialogIsOpen Then
elapsedMinutes += 1
dialogIsOpen = True
If MsgBox(String.Format("{0} minutes have elapsed since the text was saved. Save it now? ",
elapsedMinutes), MsgBoxStyle.YesNoCancel Or MsgBoxStyle.Question,
"Save Text") = MsgBoxResult.Yes Then
If dialogIsOpen Then
Button1_Click(Me, EventArgs.Empty)
dialogIsOpen = False
End If
End If
End If
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If String.IsNullOrEmpty(SaveFileDialog1.FileName) Then
If SaveFileDialog1.ShowDialog() = DialogResult.OK Then
sw = New StreamWriter(SaveFileDialog1.FileName, False)
End If
End If
txt = TextBox1.Text
hasChanged = False
elapsedMinutes = 0
timer.Stop()
End Sub
Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
If sw IsNot Nothing Then
sw.Write(txt)
sw.Close()
End If
End Sub
End Class
The example requires that you add the following controls to the form:
A TextBox control named
TextBox1
(its default name).A Button control named
Button1
(its default name).A SaveFileDialog control named
SaveSaveFileDialog1
(its default name) .
When SynchronizingObject is null
, the method that handles the Elapsed event is called on a thread from the system-thread pool. For more information on system-thread pools, see ThreadPool.
When the Elapsed event is handled by a visual Windows Forms component, such as a button, accessing the component through the system-thread pool might result in an exception or just might not work. Avoid this effect by setting SynchronizingObject to a Windows Forms component, which causes the method that handles the Elapsed event to be called on the same thread that the component was created on.
Note
Even if the SynchronizingObject property is not null
, Elapsed events can occur after the Dispose or Stop method has been called or after the Enabled property has been set to false
, because the signal to raise the Elapsed event is always queued for execution on a thread pool thread. One way to resolve this race condition is to set a flag that tells the event handler for the Elapsed event to ignore subsequent events.
If the Timer is used inside Visual Studio in a Windows Forms designer, SynchronizingObject is automatically set to the control that contains the Timer. For example, if you place a Timer on a designer for Form1
(which inherits from Form), the SynchronizingObject property of Timer is set to the instance of Form1
.
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
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