Cenni preliminari sull'utilizzo di controlli in Windows FormOverview of Using Controls in Windows Forms

In questo argomento vengono descritti gli elementi fondamentali di un'applicazione Windows Form e fornisce un esempio semplice che utilizza i controlli e gestisce gli eventi in un'applicazione Windows Form.This topic describes the essential elements of a Windows Forms application and provides a simple example that uses controls and handles events in a Windows Forms application.

Applicazioni Windows Form sempliciSimple Windows Forms Applications

Come minimo, un'applicazione Windows Forms include gli elementi seguenti:At a minimum, a Windows Forms application consists of the following elements:

  • Una o più classi che derivano da System.Windows.Forms.Form.One or more classes that derive from System.Windows.Forms.Form.

  • Oggetto Main metodo che richiama il static (shared in Visual Basic) Run metodo e passa un Form istanza a esso.A Main method that invokes the static (shared in Visual Basic) Run method and passes a Form instance to it. Il Run metodo elabora i messaggi dal sistema operativo per l'applicazione.The Run method processes messages from the operating system to the application.

Esempio di codice seguente mostra gli elementi essenziali di un'applicazione Windows Form.The following code example shows the essential elements of a Windows Forms application.

Option Explicit  
Option Strict  

Imports System  
Imports System.Windows.Forms  

Public Class MyForm  
   Inherits Form  

   Public Sub New()  
      Me.Text = "Hello World"  
   End Sub 'New  

   <STAThread()> _  
   Public Shared Sub Main()  
      Dim aform As New MyForm()  
      ' The Application.Run method processes messages from the operating system   
      ' to your application. If you comment out the next line of code,   
      ' your application will compile and execute, but because it is not in the  
      ' message loop, it will exit after an instance of the form is created.  
      Application.Run(aform)  
   End Sub  
End Class  
using System;  
using System.Windows.Forms;  

public class MyForm : Form {  

   public MyForm() {  
      this.Text = "Hello World";  
   }  
   [STAThread]  
   public static void Main(string[] args) {  
     MyForm aform = new MyForm();  
// The Application.Run method processes messages from the operating system   
// to your application. If you comment out the next line of code,   
// your application will compile and execute, but because it is not in the // message loop, it will exit after an instance of the form is created.  
      Application.Run(aform);  
   }  
}  

Utilizzo dei controlli in un'applicazione Windows FormUsing Controls in a Windows Forms Application

Esempio di codice seguente illustra un'applicazione semplice che illustra come le applicazioni Windows Form usano i controlli e la gestione degli eventi.The following code example shows a simple application that illustrates how Windows Forms applications use controls and handle events. L'esempio è costituito da tre pulsanti di un form. ogni pulsante Modifica il colore di sfondo quando si fa clic.The example consists of three buttons on a form; each button changes the background color when clicked.

Option Explicit  
Option Strict  

Imports System  
Imports System.ComponentModel  
Imports System.Windows.Forms  
Imports System.Resources  
Imports System.Drawing  

Public Class MyForm  
   Inherits Form  
   Private red As Button  
   Private blue As Button  
   Private green As Button  

   Public Sub New()  
      InitializeComponent()  
   End Sub  

   Protected Overloads Overrides Sub Dispose(disposing as Boolean)  
      MyBase.Dispose(disposing)  
   End Sub  

   ' InitializeComponent is a helper method for the constructor.   
   ' It is included for consistency with code that is   
   ' auto-generated by the Windows Forms designer in Visual Studio.   
   Private Sub InitializeComponent()  

      ' Creates three buttons, sets their properties, and attaches  
      ' an event handler to each button.  
      red = New Button()  
      red.Text = "Red"  
      red.Location = New Point(100, 50)  
      red.Size = New Size(50, 50)  
      AddHandler red.Click, AddressOf button_Click  
      Controls.Add(red)  

      blue = New Button()  
      blue.Text = "Blue"  
      blue.Location = New Point(100, 100)  
      blue.Size = New Size(50, 50)  
      AddHandler blue.Click, AddressOf button_Click  
      Controls.Add(blue)  

      green = New Button()  
      green.Text = "Green"  
      green.Location = New Point(100, 150)  
      green.Size = New Size(50, 50)  
      AddHandler green.Click, AddressOf button_Click  
      Controls.Add(green)  
   End Sub  

   ' Event handler.  
   Private Sub button_Click(sender As Object, e As EventArgs)  
      If sender Is red Then  
         Me.BackColor = Color.Red  
      Else  
         If sender Is blue Then  
            Me.BackColor = Color.Blue  
         Else  
            Me.BackColor = Color.Green  
         End If  
      End If   
   End Sub  

   ' The STAThreadAttribute informs the common language runtime that  
   ' Windows Forms uses the single-threaded apartment model.  
   <STAThread()> _  
   Public Shared Sub Main()  
      Application.Run(New MyForm())  
   End Sub  
End Class  
using System;  
using System.ComponentModel;  
using System.Windows.Forms;  
using System.Resources;  
using System.Drawing;  

public class MyForm : Form {  
   private Button red;  
   private Button blue;  
   private Button green;  

   public MyForm() : base() {     
      InitializeComponent();     
   }  

   protected override void Dispose(bool disposing) {  
      base.Dispose(disposing);  
   }  

// InitializeComponent is a helper method for the constructor.   
// It is included for consistency with code that is   
// auto-generated by the Windows Forms designer in Visual Studio.   
   private void InitializeComponent() {  

// A delegate for the click event of a button. The argument to   
// the constructor contains a reference to the method that performs the   
// event handling logic.  
      EventHandler handler = new EventHandler(button_Click);  

// Creates three buttons, sets their properties, and attaches  
// an event handler to each button.  

      red = new Button();  
      red.Text = "Red";  
      red.Location = new Point(100, 50);  
      red.Size = new Size(50, 50);  
      red.Click +=handler;  
      Controls.Add(red);  

      blue = new Button();  
      blue.Text = "Blue";  
      blue.Location = new Point(100, 100);  
      blue.Size = new Size(50, 50);  
      blue.Click += handler;  
      Controls.Add(blue);  

      green = new Button();  
      green.Text = "Green";  
      green.Location = new Point(100, 150);  
      green.Size = new Size(50, 50);  
      green.Click += handler;  
      Controls.Add(green);        
      }  

   // Event handler.  
   private void button_Click(object sender, EventArgs e) {  
            if (sender == red) this.BackColor = Color.Red ;  
                  else if (sender == blue) this.BackColor = Color.Blue;  
                  else this.BackColor = Color.Green;  
        }  
   // The STAThreadAttribute informs the common language runtime that  
   // Windows Forms uses the single-threaded apartment model.  
  [STAThread]  
   public static void Main(string[] args) {  
   Application.Run(new MyForm());  
   }  

}  

Vedere ancheSee Also

Sviluppo di controlli Windows Form personalizzati con .NET FrameworkDeveloping Custom Windows Forms Controls with the .NET Framework
Nozioni fondamentali sullo sviluppo di controlli Windows FormWindows Forms Control Development Basics