Cancel (eat) event : Control Event « GUI Windows Forms « C# / CSharp Tutorial

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C# / CSharp Tutorial » GUI Windows Forms » Control Event 
23.54.2.Cancel (eat) event
Cancel (eat) event
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class TextCancelEventKeyEvent : System.Windows.Forms.Form
{
  private System.Windows.Forms.Label label1;
  private System.Windows.Forms.TextBox txtInput;
  private System.Windows.Forms.Label label2;
  private System.Windows.Forms.Label lblTrue;
  private System.Windows.Forms.Label label3;
  private System.Windows.Forms.Label lblCheck;
    private System.Windows.Forms.Label lblResults;

  public TextCancelEventKeyEvent()
  {
    InitializeComponent();
  }

  private void InitializeComponent()
  {
     this.label1 = new System.Windows.Forms.Label();
     this.txtInput = new System.Windows.Forms.TextBox();
     this.label2 = new System.Windows.Forms.Label();
     this.lblTrue = new System.Windows.Forms.Label();
     this.label3 = new System.Windows.Forms.Label();
     this.lblCheck = new System.Windows.Forms.Label();
     this.lblResults = new System.Windows.Forms.Label();
     this.SuspendLayout();
     // 
     // label1
     // 
     this.label1.Font = new System.Drawing.Font("Tahoma"14.25F(System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic), System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
     this.label1.Location = new System.Drawing.Point(4816);
     this.label1.Name = "label1";
     this.label1.Size = new System.Drawing.Size(17623);
     this.label1.TabIndex = 0;
     this.label1.Text = "ISBN Validation";
     // 
     // txtInput
     // 
     this.txtInput.Location = new System.Drawing.Point(7264);
     this.txtInput.Name = "txtInput";
     this.txtInput.TabIndex = 1;
     this.txtInput.Text = "";
     this.txtInput.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.txtInput_KeyPress);
     this.txtInput.Validating += new System.ComponentModel.CancelEventHandler(this.handleCancleEvent);
     // 
     // label2
     // 
     this.label2.Location = new System.Drawing.Point(24104);
     this.label2.Name = "label2";
     this.label2.Size = new System.Drawing.Size(8023);
     this.label2.TabIndex = 2;
     this.label2.Text = "True Number:";
     // 
     // lblTrue
     // 
     this.lblTrue.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblTrue.Location = new System.Drawing.Point(112104);
     this.lblTrue.Name = "lblTrue";
     this.lblTrue.TabIndex = 3;
     // 
     // label3
     // 
     this.label3.Location = new System.Drawing.Point(32152);
     this.label3.Name = "label3";
     this.label3.Size = new System.Drawing.Size(7223);
     this.label3.TabIndex = 4;
     this.label3.Text = "Check Digit:";
     // 
     // lblCheck
     // 
     this.lblCheck.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblCheck.Location = new System.Drawing.Point(112152);
     this.lblCheck.Name = "lblCheck";
     this.lblCheck.TabIndex = 5;
     // 
     // lblResults
     // 
     this.lblResults.Location = new System.Drawing.Point(56192);
     this.lblResults.Name = "lblResults";
     this.lblResults.Size = new System.Drawing.Size(15224);
     this.lblResults.TabIndex = 8;
     // 
     // TextCancelEventKeyEvent
     // 
     this.AutoScaleBaseSize = new System.Drawing.Size(513);
     this.ClientSize = new System.Drawing.Size(264293);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                  this.lblResults,
                                                                  this.lblCheck,
                                                                  this.label3,
                                                                  this.lblTrue,
                                                                  this.label2,
                                                                  this.txtInput,
                                                                  this.label1});
     this.ResumeLayout(false);

  }
  [STAThread]
  static void Main() 
  {
    Application.Run(new TextCancelEventKeyEvent());
  }

  private void handleCancleEvent(object sender, System.ComponentModel.CancelEventArgs e)
  {
    TextBox tb = (TextBox)sender;
    string strInput = tb.Text;
        Console.WriteLine(strInput);
  }     

  private void txtInput_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
  {
     char keyChar;
     keyChar = e.KeyChar;

     if(!Char.IsDigit(keyChar)      // 0 - 9
        &&
        keyChar != 8               // backspace
        &&
        keyChar != 13              // enter
        &&
        keyChar != 'x'
        &&
        keyChar != 45              //  dash/minus
        ){
        //  Do not display the keystroke
        e.Handled = true;
     }
  }     
}
23.54.Control Event
23.54.1.Label's Generic eventLabel's Generic event
23.54.2.Cancel (eat) eventCancel (eat) event
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