Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Gets a value indicating whether the ALT key was pressed.
Gets a value indicating whether the CTRL key was pressed.
Gets or sets a value indicating whether the event was handled.
Gets a value indicating whether the SHIFT key was pressed.
Gets or sets a value indicating whether the key event should be passed on to the underlying control.
Determines whether the specified object is equal to the current object.(Inherited from Object.)
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)
Serves as the default hash function. (Inherited from Object.)
Returns a string that represents the current object.(Inherited from Object.)
The KeyDown event occurs when the user presses any key. The KeyUp event occurs when the user releases the key. Duplicate KeyDown events occur each time the key repeats, if the key is held down, but only one KeyUp event is generated when the user releases the key.
For information about the event model, see Handling and Raising Events.
The following code examples demonstrate how to detect the state of a key press.
The following code example demonstrates how to use the KeyDown event with the Help class to display pop-up style Help to the user of the application. The example uses the properties passed to the event handler method to filter for all variations of pressing the F1 key with a modifier key. When the user presses any variation of F1 that includes any keyboard modifier, the Help class displays a pop-up window, similar to a ToolTip, near the control. If the user presses ALT+F2, a different Help pop-up is displayed with additional information.
Private Sub textBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles textBox1.KeyDown ' Determine whether the key entered is the F1 key. If it is, display Help. If e.KeyCode = Keys.F1 AndAlso (e.Alt OrElse e.Control OrElse e.Shift) Then ' Display a pop-up Help topic to assist the user. Help.ShowPopup(textBox1, "Enter your name.", New Point(textBox1.Bottom, textBox1.Right)) ElseIf e.KeyCode = Keys.F2 AndAlso e.Modifiers = Keys.Alt Then ' Display a pop-up Help topic to provide additional assistance to the user. Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.", _ New Point(textBox1.Top, Me.textBox1.Left)) End If End Sub 'textBox1_KeyDown
Private Sub treeView1_KeyDown(sender As Object, _ e As KeyEventArgs) Handles treeView1.KeyDown ' If the 'Alt' and 'E' keys are pressed, ' allow the user to edit the TreeNode label. If e.Alt And e.KeyCode = Keys.E Then treeView1.LabelEdit = True ' If there is a TreeNode under the mose cursor, begin editing. Dim editNode As TreeNode = treeView1.GetNodeAt( _ treeView1.PointToClient(System.Windows.Forms.Control.MousePosition)) If (editNode IsNot Nothing) Then editNode.BeginEdit() End If End If End Sub Private Sub treeView1_AfterLabelEdit(sender As Object, _ e As NodeLabelEditEventArgs) Handles treeView1.AfterLabelEdit ' Disable the ability to edit the TreeNode labels. treeView1.LabelEdit = False End Sub
' 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 'textBox1_KeyDown ' 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 'textBox1_KeyPress
Available since 1.1
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.