Visão geral do uso de controles Windows Forms
Este tópico descreve os elementos essenciais de um aplicativo Windows Forms e fornece um exemplo simples que usa controles e trata os eventos em um aplicativo Windows Forms.
Aplicativos de formulários do Windows simples
No mínimo, um aplicativo Windows Forms consiste nos seguintes elementos:
Uma ou mais classes que derivam de System.Windows.Forms.Form.
A Main método chama o static (shared em Visual Basic) Run método e passar um Form instância para o proprietário. O Run método processa mensagens do sistema operacional para o aplicativo.
O exemplo de código a seguir mostra os elementos essenciais de um aplicativo Windows Forms.
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);
}
}
Uso de controles em um aplicativo do Windows Forms
O exemplo de código a seguir mostra um aplicativo simples que ilustra como os aplicativos Windows Forms usam controles e manipulam eventos. O exemplo consiste em três botões em um formulário; cada botão altera a cor de plano de fundo quando clicado.
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());
}
}
Consulte também
Conceitos
Noções básicas de desenvolvimento de controle de formulários do Windows
Outros recursos
Desenvolvendo controles de formulários do Windows personalizada com o.NET Framework