Control.IsInputKey(Keys) Method
Definition
Important
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Determines whether the specified key is a regular input key or a special key that requires preprocessing.
protected:
virtual bool IsInputKey(System::Windows::Forms::Keys keyData);protected virtual bool IsInputKey (System.Windows.Forms.Keys keyData);abstract member IsInputKey : System.Windows.Forms.Keys -> bool
override this.IsInputKey : System.Windows.Forms.Keys -> boolProtected Overridable Function IsInputKey (keyData As Keys) As BooleanParameters
Returns
true if the specified key is a regular input key; otherwise, false.
Examples
The following code example shows you how to override the IsInputKey method for a TextBox control. In this example, the TabTextBox class handles the TAB key. When the TabTextBox has the focus and the user presses the TAB key four spaces are added at the text insertion point, replacing any selected text. By default, the TextBox control handles the TAB key by moving the input focus to the next control. In this case, the keypress never reaches the OnKeyDown method override. To prevent this default behavior, the IsInputKey method override returns true when the user presses the TAB key. For all other keypresses, the IsInputKey method override returns the result of calling the base-class version of the method.
using System.Windows.Forms;
public class Form1 : Form
{
public Form1()
{
FlowLayoutPanel panel = new FlowLayoutPanel();
TabTextBox tabTextBox1 = new TabTextBox();
tabTextBox1.Text = "TabTextBox";
panel.Controls.Add(tabTextBox1);
TextBox textBox1 = new TextBox();
textBox1.Text = "Normal TextBox";
panel.Controls.Add(textBox1);
this.Controls.Add(panel);
}
}
class TabTextBox : TextBox
{
protected override bool IsInputKey(Keys keyData)
{
if (keyData == Keys.Tab)
{
return true;
}
else
{
return base.IsInputKey(keyData);
}
}
protected override void OnKeyDown(KeyEventArgs e)
{
if (e.KeyData == Keys.Tab)
{
this.SelectedText = " ";
}
else
{
base.OnKeyDown(e);
}
}
}
Imports System.Windows.Forms
Public Class Form1
Inherits Form
Public Sub New()
Dim panel As New FlowLayoutPanel()
Dim tabTextBox1 As New TabTextBox()
tabTextBox1.Text = "TabTextBox"
panel.Controls.Add(tabTextBox1)
Dim textBox1 As New TextBox()
textBox1.Text = "Normal TextBox"
panel.Controls.Add(textBox1)
Me.Controls.Add(panel)
End Sub
End Class
Class TabTextBox
Inherits TextBox
Protected Overrides Function IsInputKey( _
ByVal keyData As System.Windows.Forms.Keys) As Boolean
If keyData = Keys.Tab Then
Return True
Else
Return MyBase.IsInputKey(keyData)
End If
End Function
Protected Overrides Sub OnKeyDown( _
ByVal e As System.Windows.Forms.KeyEventArgs)
If e.KeyData = Keys.Tab Then
Me.SelectedText = " "
Else
MyBase.OnKeyDown(e)
End If
End Sub
End Class
Remarks
Call the IsInputKey method to determine whether the key specified by the keyData parameter is an input key that the control wants. This method is called during window message preprocessing to determine whether the specified input key should be preprocessed or sent directly to the control. If IsInputKey returns true, the specified key is sent directly to the control. If IsInputKey returns false, the specified key is preprocessed and only sent to the control if it is not consumed by the preprocessing phase. Keys that are preprocessed include the TAB, RETURN, ESC, and the UP ARROW, DOWN ARROW, LEFT ARROW, and RIGHT ARROW keys.
