Control.KeyPress Kejadian

Definisi

Ruang nama:

System.Windows.Forms

Rakitan:

System.Windows.Forms.dll

Terjadi ketika karakter. spasi atau tombol backspace ditekan saat kontrol memiliki fokus.

public:
 event System::Windows::Forms::KeyPressEventHandler ^ KeyPress;

public event System.Windows.Forms.KeyPressEventHandler? KeyPress;

member this.KeyPress : System.Windows.Forms.KeyPressEventHandler 

Public Custom Event KeyPress As KeyPressEventHandler 

Jenis Acara

KeyPressEventHandler

Contoh

Contoh kode berikut menggunakan KeyPress peristiwa untuk mencegah karakter memasukkan kontrol.

   // Boolean flag used to determine when a character other than a number is entered.
private:
   bool nonNumberEntered;

   // Handle the KeyDown event to determine the type of character entered into the control.
   void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
   {
      // Initialize the flag to false.
      nonNumberEntered = false;

      // Determine whether the keystroke is a number from the top of the keyboard.
      if ( e->KeyCode < Keys::D0 || e->KeyCode > Keys::D9 )
      {
         // Determine whether the keystroke is a number from the keypad.
         if ( e->KeyCode < Keys::NumPad0 || e->KeyCode > Keys::NumPad9 )
         {
            // Determine whether the keystroke is a backspace.
            if ( e->KeyCode != Keys::Back )
            {
               // A non-numerical keystroke was pressed.
               // Set the flag to true and evaluate in KeyPress event.
               nonNumberEntered = true;
            }
         }
      }
      //If shift key was pressed, it's not a number.
      if (Control::ModifierKeys == Keys::Shift) {
         nonNumberEntered = true;
      }
   }

   // This event occurs after the KeyDown event and can be used to prevent
   // characters from entering the control.
   void textBox1_KeyPress( Object^ /*sender*/, System::Windows::Forms::KeyPressEventArgs^ e )
   {
      // Check for the flag being set in the KeyDown event.
      if ( nonNumberEntered == true )
      {         // Stop the character from being entered into the control since it is non-numerical.
         e->Handled = true;
      }
   }

// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
    //If shift key was pressed, it's not a number.
    if (Control.ModifierKeys == Keys.Shift) {
        nonNumberEntered = true;
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

 ' Boolean flag used to determine when a character other than a number is entered.
 Private nonNumberEntered As Boolean = False


 ' Handle the KeyDown event to determine the type of character entered into the control.
 Private Sub textBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
      Handles textBox1.KeyDown
     ' Initialize the flag to false.
     nonNumberEntered = False
   
     ' Determine whether the keystroke is a number from the top of the keyboard.
     If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then
         ' Determine whether the keystroke is a number from the keypad.
         If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then
             ' Determine whether the keystroke is a backspace.
             If e.KeyCode <> Keys.Back Then
                 ' A non-numerical keystroke was pressed. 
                 ' Set the flag to true and evaluate in KeyPress event.
                 nonNumberEntered = True
             End If
         End If
     End If
     'If shift key was pressed, it's not a number.
     If Control.ModifierKeys = Keys.Shift Then
         nonNumberEntered = true
     End If
 End Sub


 ' This event occurs after the KeyDown event and can be used 
 ' to prevent characters from entering the control.
 Private Sub textBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) _
     Handles textBox1.KeyPress
     ' Check for the flag being set in the KeyDown event.
     If nonNumberEntered = True Then
         ' Stop the character from being entered into the control since it is non-numerical.
         e.Handled = True
     End If
 End Sub

Contoh kode berikut menunjukkan urutan naiknya KeyDownperistiwa , KeyUp dan KeyPress , juga cara mendaftarkan penanganan aktivitas pada mereka.

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
        textBox2.Multiline = true;
        textBox2.ScrollBars = ScrollBars.Both;

        //Setup events that listens on keypress
        textBox1.KeyDown += TextBox1_KeyDown;
        textBox1.KeyPress += TextBox1_KeyPress;
        textBox1.KeyUp += TextBox1_KeyUp;
    }

    // Handle the KeyUp event to print the type of character entered into the control.
    private void TextBox1_KeyUp(object sender, KeyEventArgs e)
    {
        textBox2.AppendText( $"KeyUp code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + "\r\n");
    }

    // Handle the KeyPress event to print the type of character entered into the control.
    private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        textBox2.AppendText( $"KeyPress keychar: {e.KeyChar}" + "\r\n");
    }

    // Handle the KeyDown event to print the type of character entered into the control.
    private void TextBox1_KeyDown(object sender, KeyEventArgs e)
    {
        textBox2.AppendText( $"KeyDown code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + "\r\n");
    }
}

Public Class Form2

    ' Handle the KeyDown event to print the type of character entered into the control.
    Private Sub TextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles TextBox1.KeyDown
        TextBox2.AppendText($"KeyDown code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + vbCrLf)
    End Sub

    ' Handle the KeyPress event to print the type of character entered into the control.
    Private Sub TextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TextBox1.KeyPress
        TextBox2.AppendText($"KeyPress keychar: {e.KeyChar}" + vbCrLf)
    End Sub

    ' Handle the KeyUp event to print the type of character entered into the control.
    Private Sub TextBox1_KeyUp(sender As Object, e As KeyEventArgs) Handles TextBox1.KeyUp
        TextBox2.AppendText($"KeyUp code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + vbCrLf)
    End Sub

End Class

Keterangan

Peristiwa utama terjadi dalam urutan berikut:

1. KeyDown

2. KeyPress

3. KeyUp

Peristiwa KeyPress ini tidak dinaikkan oleh kunci non-karakter selain spasi dan backspace; namun, kunci non-karakter memang menaikkan KeyDown peristiwa dan KeyUp .

KeyChar Gunakan properti untuk mengambil sampel penekanan tombol pada durasi dan untuk mengonsumsi atau memodifikasi subset penekanan tombol umum.

Untuk menangani peristiwa keyboard hanya pada tingkat formulir dan tidak mengaktifkan kontrol lain untuk menerima peristiwa keyboard, atur KeyPressEventArgs.Handled properti dalam metode penanganan peristiwa formulir KeyPress Anda ke true.

Untuk informasi selengkapnya tentang menangani peristiwa, lihat Menangani dan Menaikkan Peristiwa.

Lihat juga

• KeyChar
• OnKeyPress(KeyPressEventArgs)
• IsInputChar(Char)
• KeyUp
• KeyDown