Cara: Mengubah Input Keyboard ke Kontrol Standar
Formulir Windows menyediakan kemampuan untuk menggunakan dan memodifikasi input keyboard. Mengkonsumsi kunci mengacu pada penanganan kunci dalam metode atau penanganan aktivitas sehingga metode dan peristiwa lain lebih jauh ke bawah antrean pesan tidak menerima nilai kunci. Memodifikasi kunci mengacu pada memodifikasi nilai kunci sehingga metode dan penanganan aktivitas lebih jauh ke bawah antrean pesan menerima nilai kunci yang berbeda. Topik ini menunjukkan cara menyelesaikan tugas-tugas ini.
Untuk menggunakan kunci
Dalam penanganan KeyPress aktivitas, atur Handled properti kelas ke KeyPressEventArgs
true
.-atau-
Dalam penanganan KeyDown aktivitas, atur Handled properti kelas ke KeyEventArgs
true
.Catatan
Handled Mengatur properti di KeyDown penanganan aktivitas tidak mencegah KeyPress peristiwa dan KeyUp dinaikkan untuk penekanan tombol saat ini. SuppressKeyPress Gunakan properti untuk tujuan ini.
Contoh berikut adalah kutipan dari
switch
pernyataan yang memeriksa KeyChar properti yang KeyPressEventArgs diterima oleh KeyPress penanganan aktivitas. Kode ini menggunakan kunci karakter 'A' dan 'a'.// Consume 'A' and 'a'. case (char)65: case (char)97: MessageBox.Show("Control.KeyPress: '" + e.KeyChar.ToString() + "' consumed."); e.Handled = true; break;
' Consume 'A' and 'a'. Case ChrW(65), ChrW(97) MessageBox.Show(("Control.KeyPress: '" + _ e.KeyChar.ToString() + "' consumed.")) e.Handled = True
Untuk mengubah kunci karakter standar
Dalam penanganan KeyPress aktivitas, atur KeyChar properti KeyPressEventArgs kelas ke nilai kunci karakter baru.
Contoh berikut adalah kutipan dari
switch
pernyataan yang memodifikasi 'B' menjadi 'A' dan 'b' menjadi 'a'. Perhatikan bahwa Handled properti KeyPressEventArgs parameter diatur kefalse
, sehingga nilai kunci baru disebarkan ke metode dan peristiwa lain dalam antrean pesan.// Detect 'B', modify it to 'A', and forward the key. case (char)66: MessageBox.Show("Control.KeyPress: '" + e.KeyChar.ToString() + "' replaced by 'A'."); e.KeyChar = (char)65; e.Handled = false; break; // Detect 'b', modify it to 'a', and forward the key. case (char)98: MessageBox.Show("Control.KeyPress: '" + e.KeyChar.ToString() + "' replaced by 'a'."); e.KeyChar = (char)97; e.Handled = false; break;
' Modify 'B' to 'A' and forward the key. Case ChrW(66) MessageBox.Show(("Control.KeyPress: '" + _ e.KeyChar.ToString() + "' replaced by 'A'.")) e.KeyChar = ChrW(65) e.Handled = False ' Modify 'b' to 'a' and forward the key. Case ChrW(98) MessageBox.Show(("Control.KeyPress: '" + _ e.KeyChar.ToString() + "' replaced by 'a'.")) e.KeyChar = ChrW(97) e.Handled = False
Untuk mengubah kunci noncharacter
Ambil alih Control metode yang memproses pesan Windows, mendeteksi pesan WM_KEYDOWN atau WM_SYSKEYDOWN, dan mengatur WParam properti Message parameter ke Keys nilai yang mewakili kunci noncharacter baru.
Contoh kode berikut menunjukkan cara mengambil alih PreProcessMessage metode kontrol untuk mendeteksi kunci F1 hingga F9 dan memodifikasi penekanan tombol F3 ke F1. Untuk informasi selengkapnya tentang Control metode yang dapat Anda ambil alih untuk mencegat pesan keyboard, lihat Input Pengguna di Aplikasi Formulir Windows dan Cara Kerja Input Keyboard.
// Detect F1 through F9 during preprocessing and modify F3. public override bool PreProcessMessage(ref Message m) { if (m.Msg == WM_KEYDOWN) { Keys keyCode = (Keys)m.WParam & Keys.KeyCode; // Detect F1 through F9. switch (keyCode) { case Keys.F1: case Keys.F2: case Keys.F3: case Keys.F4: case Keys.F5: case Keys.F6: case Keys.F7: case Keys.F8: case Keys.F9: MessageBox.Show("Control.PreProcessMessage: '" + keyCode.ToString() + "' pressed."); // Replace F3 with F1, so that ProcessKeyMessage will // receive F1 instead of F3. if (keyCode == Keys.F3) { m.WParam = (IntPtr)Keys.F1; MessageBox.Show("Control.PreProcessMessage: '" + keyCode.ToString() + "' replaced by F1."); } break; } } // Send all other messages to the base method. return base.PreProcessMessage(ref m); }
' Detect F1 through F9 during preprocessing and modify F3. Public Overrides Function PreProcessMessage(ByRef m As Message) _ As Boolean If m.Msg = WM_KEYDOWN Then Dim keyCode As Keys = CType(m.WParam, Keys) And Keys.KeyCode ' Detect F1 through F9. Select Case keyCode Case Keys.F1, Keys.F2, Keys.F3, Keys.F4, Keys.F5, _ Keys.F6, Keys.F7, Keys.F8, Keys.F9 MessageBox.Show(("Control.PreProcessMessage: '" + _ keyCode.ToString() + "' pressed.")) ' Replace F3 with F1, so that ProcessKeyMessage will ' receive F1 instead of F3. If keyCode = Keys.F3 Then m.WParam = CType(Keys.F1, IntPtr) MessageBox.Show(("Control.PreProcessMessage: '" + _ keyCode.ToString() + "' replaced by F1.")) End If End Select End If ' Send all other messages to the base method. Return MyBase.PreProcessMessage(m) End Function
Contoh
Contoh kode berikut adalah aplikasi lengkap untuk contoh kode di bagian sebelumnya. Aplikasi ini menggunakan kontrol kustom yang berasal dari TextBox kelas untuk mengonsumsi dan memodifikasi input keyboard.
using System;
using System.Drawing;
using System.Windows.Forms;
namespace KeyboardInput
{
class Form1 : Form
{
// The following Windows message value is defined in Winuser.h.
private int WM_KEYDOWN = 0x100;
CustomTextBox CustomTextBox1 = new CustomTextBox();
[STAThread]
public static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
public Form1()
{
this.AutoSize = true;
this.Controls.Add(CustomTextBox1);
CustomTextBox1.KeyPress +=
new KeyPressEventHandler(CustomTextBox1_KeyPress);
}
// Consume and modify several character keys.
void CustomTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
switch (e.KeyChar)
{
// Consume 'A' and 'a'.
case (char)65:
case (char)97:
MessageBox.Show("Control.KeyPress: '" +
e.KeyChar.ToString() + "' consumed.");
e.Handled = true;
break;
// Detect 'B', modify it to 'A', and forward the key.
case (char)66:
MessageBox.Show("Control.KeyPress: '" +
e.KeyChar.ToString() + "' replaced by 'A'.");
e.KeyChar = (char)65;
e.Handled = false;
break;
// Detect 'b', modify it to 'a', and forward the key.
case (char)98:
MessageBox.Show("Control.KeyPress: '" +
e.KeyChar.ToString() + "' replaced by 'a'.");
e.KeyChar = (char)97;
e.Handled = false;
break;
}
}
}
public class CustomTextBox : TextBox
{
// The following Windows message value is defined in Winuser.h.
private int WM_KEYDOWN = 0x100;
public CustomTextBox()
{
this.Size = new Size(100, 100);
this.AutoSize = false;
}
// Detect F1 through F9 during preprocessing and modify F3.
public override bool PreProcessMessage(ref Message m)
{
if (m.Msg == WM_KEYDOWN)
{
Keys keyCode = (Keys)m.WParam & Keys.KeyCode;
// Detect F1 through F9.
switch (keyCode)
{
case Keys.F1:
case Keys.F2:
case Keys.F3:
case Keys.F4:
case Keys.F5:
case Keys.F6:
case Keys.F7:
case Keys.F8:
case Keys.F9:
MessageBox.Show("Control.PreProcessMessage: '" +
keyCode.ToString() + "' pressed.");
// Replace F3 with F1, so that ProcessKeyMessage will
// receive F1 instead of F3.
if (keyCode == Keys.F3)
{
m.WParam = (IntPtr)Keys.F1;
MessageBox.Show("Control.PreProcessMessage: '" +
keyCode.ToString() + "' replaced by F1.");
}
break;
}
}
// Send all other messages to the base method.
return base.PreProcessMessage(ref m);
}
// Detect F1 through F9 during processing.
protected override bool ProcessKeyMessage(ref Message m)
{
if (m.Msg == WM_KEYDOWN)
{
Keys keyCode = (Keys)m.WParam & Keys.KeyCode;
// Detect F1 through F9.
switch (keyCode)
{
case Keys.F1:
case Keys.F2:
case Keys.F3:
case Keys.F4:
case Keys.F5:
case Keys.F6:
case Keys.F7:
case Keys.F8:
case Keys.F9:
MessageBox.Show("Control.ProcessKeyMessage: '" +
keyCode.ToString() + "' pressed.");
break;
}
}
// Send all messages to the base method.
return base.ProcessKeyMessage(ref m);
}
}
}
Imports System.Drawing
Imports System.Security
Imports System.Security.Permissions
Imports System.Windows.Forms
Namespace KeyboardInput
Class Form1
Inherits Form
' The following Windows message value is defined in Winuser.h.
Private WM_KEYDOWN As Integer = &H100
Private WithEvents CustomTextBox1 As New CustomTextBox()
<STAThread()> _
Public Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
Public Sub New()
Me.AutoSize = True
Me.Controls.Add(CustomTextBox1)
End Sub
' Consume and modify several character keys.
Sub CustomTextBox1_KeyPress(ByVal sender As Object, _
ByVal e As KeyPressEventArgs) Handles CustomTextBox1.KeyPress
Select Case e.KeyChar
' Consume 'A' and 'a'.
Case ChrW(65), ChrW(97)
MessageBox.Show(("Control.KeyPress: '" + _
e.KeyChar.ToString() + "' consumed."))
e.Handled = True
' Modify 'B' to 'A' and forward the key.
Case ChrW(66)
MessageBox.Show(("Control.KeyPress: '" + _
e.KeyChar.ToString() + "' replaced by 'A'."))
e.KeyChar = ChrW(65)
e.Handled = False
' Modify 'b' to 'a' and forward the key.
Case ChrW(98)
MessageBox.Show(("Control.KeyPress: '" + _
e.KeyChar.ToString() + "' replaced by 'a'."))
e.KeyChar = ChrW(97)
e.Handled = False
End Select
End Sub
End Class
Public Class CustomTextBox
Inherits TextBox
' The following Windows message value is defined in Winuser.h.
Private WM_KEYDOWN As Integer = &H100
Public Sub New()
Me.Size = New Size(100, 100)
Me.AutoSize = False
End Sub
' Detect F1 through F9 during preprocessing and modify F3.
Public Overrides Function PreProcessMessage(ByRef m As Message) _
As Boolean
If m.Msg = WM_KEYDOWN Then
Dim keyCode As Keys = CType(m.WParam, Keys) And Keys.KeyCode
' Detect F1 through F9.
Select Case keyCode
Case Keys.F1, Keys.F2, Keys.F3, Keys.F4, Keys.F5, _
Keys.F6, Keys.F7, Keys.F8, Keys.F9
MessageBox.Show(("Control.PreProcessMessage: '" + _
keyCode.ToString() + "' pressed."))
' Replace F3 with F1, so that ProcessKeyMessage will
' receive F1 instead of F3.
If keyCode = Keys.F3 Then
m.WParam = CType(Keys.F1, IntPtr)
MessageBox.Show(("Control.PreProcessMessage: '" + _
keyCode.ToString() + "' replaced by F1."))
End If
End Select
End If
' Send all other messages to the base method.
Return MyBase.PreProcessMessage(m)
End Function
' Detect F1 through F9 during processing.
Protected Overrides Function ProcessKeyMessage(ByRef m As Message) _
As Boolean
If m.Msg = WM_KEYDOWN Then
Dim keyCode As Keys = CType(m.WParam, Keys) And Keys.KeyCode
' Detect F1 through F9.
Select Case keyCode
Case Keys.F1, Keys.F2, Keys.F3, Keys.F4, Keys.F5, _
Keys.F6, Keys.F7, Keys.F8, Keys.F9
MessageBox.Show(("Control.ProcessKeyMessage: '" + _
keyCode.ToString() + "' pressed."))
End Select
End If
' Send all messages to the base method.
Return MyBase.ProcessKeyMessage(m)
End Function
End Class
End Namespace
Mengompilasi Kode
Contoh ini membutuhkan:
- Referensi ke rakitan System, System.Drawing dan System.Windows.Forms.
Baca juga
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