using System.ComponentModel; using System.Windows.Forms;
{
{
// This delegate enables asynchronous calls for setting
// the text property on a TextBox control.
// This thread is used to demonstrate both thread-safe and
// unsafe ways to call a Windows Forms control.
// This BackgroundWorker is used to demonstrate the
// preferred way of performing asynchronous operations.
private BackgroundWorker backgroundWorker1
;
private Button setTextBackgroundWorkerBtn
;
private System.ComponentModel.IContainer components
= null;
{
InitializeComponent();
}
{
if (disposing
&& (components
!= null)) {
components.Dispose();
}
}
// This event handler creates a thread that calls a
// Windows Forms control in an unsafe way.
EventArgs e)
{
new Thread
(new ThreadStart
(this.ThreadProcUnsafe));
}
// This method is executed on the worker thread and makes
// an unsafe call on the TextBox control.
{
this.textBox1.Text = "This text was set unsafely."; }
// This event handler creates a thread that calls a
// Windows Forms control in a thread-safe way.
EventArgs e)
{
}
// This method is executed on the worker thread and makes
// a thread-safe call on the TextBox control.
{
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.
{
// 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.textBox1.InvokeRequired) {
SetTextCallback d
= new SetTextCallback
(SetText
); }
{
this.textBox1.Text = 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.
EventArgs e)
{
this.backgroundWorker1.RunWorkerAsync(); }
// 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.
RunWorkerCompletedEventArgs e)
{
"This text was set safely by BackgroundWorker.";
}
#region Windows Form Designer generated code
{
this.textBox1 = new System.Windows.Forms.TextBox(); this.setTextUnsafeBtn = new System.Windows.Forms.Button(); this.setTextSafeBtn = new System.Windows.Forms.Button(); this.setTextBackgroundWorkerBtn = new System.Windows.Forms.Button(); this.backgroundWorker1 = new System.ComponentModel.BackgroundWorker(); //
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(12,
12); this.textBox1.Name = "textBox1"; this.textBox1.Size = new System.Drawing.Size(240,
20); this.textBox1.TabIndex = 0; //
// setTextUnsafeBtn
//
this.setTextUnsafeBtn.Location = new System.Drawing.Point(15,
55); this.setTextUnsafeBtn.Name = "setTextUnsafeBtn"; this.setTextUnsafeBtn.TabIndex = 1; this.setTextUnsafeBtn.Text = "Unsafe Call"; this.setTextUnsafeBtn.Click += new System.EventHandler(this.setTextUnsafeBtn_Click); //
// setTextSafeBtn
//
this.setTextSafeBtn.Location = new System.Drawing.Point(96,
55); this.setTextSafeBtn.Name = "setTextSafeBtn"; this.setTextSafeBtn.TabIndex = 2; this.setTextSafeBtn.Text = "Safe Call"; this.setTextSafeBtn.Click += new System.EventHandler(this.setTextSafeBtn_Click); //
// setTextBackgroundWorkerBtn
//
this.setTextBackgroundWorkerBtn.Location = new System.Drawing.Point(177,
55); this.setTextBackgroundWorkerBtn.Name = "setTextBackgroundWorkerBtn"; this.setTextBackgroundWorkerBtn.TabIndex = 3; this.setTextBackgroundWorkerBtn.Text = "Safe BW Call"; this.setTextBackgroundWorkerBtn.Click += new System.EventHandler(this.setTextBackgroundWorkerBtn_Click); //
// backgroundWorker1
//
this.backgroundWorker1.RunWorkerCompleted += new System.ComponentModel.RunWorkerCompletedEventHandler(this.backgroundWorker1_RunWorkerCompleted); //
// Form1
//
this.ClientSize = new System.Drawing.Size(268,
96); this.Controls.Add(this.setTextBackgroundWorkerBtn); this.Controls.Add(this.setTextUnsafeBtn);
}
#endregion
[STAThread]
{
Application.EnableVisualStyles();
Application
.Run(new Form1
()); }
}
}