using System;
using ;
using ;
using ;
namespace CrossThreadDemo
{
public class Form1 : Form
{
// This delegate enables asynchronous calls for setting
// the text property on a TextBox control.
delegate void SetTextCallback(string text);
// This thread is used to demonstrate both thread-safe and
// unsafe ways to call a Windows Forms control.
private Thread demoThread = null;
// This BackgroundWorker is used to demonstrate the
// preferred way of performing asynchronous operations.
private BackgroundWorker backgroundWorker1;
private TextBox textBox1;
private Button setTextUnsafeBtn;
private Button setTextSafeBtn;
private Button setTextBackgroundWorkerBtn;
private components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
();
}
base.Dispose(disposing);
}
// This event handler creates a thread that calls a
// Windows Forms control in an unsafe way.
private void setTextUnsafeBtn_Click(
object sender,
EventArgs e)
{
this.demoThread =
new Thread(new ThreadStart(this.ThreadProcUnsafe));
this.();
}
// This method is executed on the worker thread and makes
// an unsafe call on the TextBox control.
private void ThreadProcUnsafe()
{
this. = "This text was set unsafely.";
}
// This event handler creates a thread that calls a
// Windows Forms control in a thread-safe way.
private void setTextSafeBtn_Click(
object sender,
EventArgs e)
{
this.demoThread =
new Thread(new ThreadStart(this.ThreadProcSafe));
this.();
}
// This method is executed on the worker thread and makes
// a thread-safe call on the TextBox control.
private void ThreadProcSafe()
{
this.SetText("This text was set safely.");
}
// This method demonstrates a pattern for making thread-safe
// calls on a Windows Forms control.
//
// If the calling thread is different from the thread that
// created the TextBox control, this method creates a
// SetTextCallback and calls itself asynchronously using the
// Invoke method.
//
// If the calling thread is the same as the thread that created
// the TextBox control, the Text property is set directly.
private void SetText(string text)
{
// InvokeRequired required compares the thread ID of the
// calling thread to the thread ID of the creating thread.
// If these threads are different, it returns true.
if (this.)
{
SetTextCallback d = new SetTextCallback(SetText);
this.Invoke(d, new object[] { text });
}
else
{
this. = text;
}
}
// This event handler starts the form's
// BackgroundWorker by calling RunWorkerAsync.
//
// The Text property of the TextBox control is set
// when the BackgroundWorker raises the RunWorkerCompleted
// event.
private void setTextBackgroundWorkerBtn_Click(
object sender,
EventArgs e)
{
this.();
}
// This event handler sets the Text property of the TextBox
// control. It is called on the thread that created the
// TextBox control, so the call is thread-safe.
//
// BackgroundWorker is the preferred way to perform asynchronous
// operations.
private void backgroundWorker1_RunWorkerCompleted(
object sender,
RunWorkerCompletedEventArgs e)
{
this. =
"This text was set safely by BackgroundWorker.";
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.textBox1 = new ();
this.setTextUnsafeBtn = new ();
this.setTextSafeBtn = new ();
this.setTextBackgroundWorkerBtn = new ();
this.backgroundWorker1 = new ();
this.SuspendLayout();
//
// textBox1
//
this. = new (12, 12);
this. = "textBox1";
this. = new (240, 20);
this. = 0;
//
// setTextUnsafeBtn
//
this. = new (15, 55);
this. = "setTextUnsafeBtn";
this. = 1;
this. = "Unsafe Call";
this. += new (this.setTextUnsafeBtn_Click);
//
// setTextSafeBtn
//
this. = new (96, 55);
this. = "setTextSafeBtn";
this. = 2;
this. = "Safe Call";
this. += new (this.setTextSafeBtn_Click);
//
// setTextBackgroundWorkerBtn
//
this. = new (177, 55);
this. = "setTextBackgroundWorkerBtn";
this. = 3;
this. = "Safe BW Call";
this. += new (this.setTextBackgroundWorkerBtn_Click);
//
// backgroundWorker1
//
this. += new (this.backgroundWorker1_RunWorkerCompleted);
//
// Form1
//
this.ClientSize = new (268, 96);
this.(this.setTextBackgroundWorkerBtn);
this.(this.setTextSafeBtn);
this.(this.setTextUnsafeBtn);
this.(this.textBox1);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
[STAThread]
static void Main()
{
();
(new Form1());
}
}
}