#636 – Keyboard Events that Fire When A Key Is Held Down

When you hold a key down in Windows, the key begins to repeat after a short delay, as if you you were repeatedly pressing it.

While a key is held down, the PreviewKeyDown, KeyDown and PreviewTextInput events will fire repeatedly.

You can detect whether a keypress is the original/first keypress, or one of the repeats, by checking the KeyEventArgs.IsRepeat property.

Let’s say we press the ‘a’ key while a TextBox has focus and hold it down long enough for three ‘a’ characters to be inserted.  We’ll get the following events:

• PreviewKeyDown, Key = A, IsRepeat = False
• KeyDown, Key = A, IsRepeat = False
• PreviewTextInput, Text = a
• (TextBox contains “a”)
• PreviewKeyDown, Key = A, IsRepeat = True
• KeyDown, Key = A, IsRepeat = True
• PreviewTextInput, Text = a
• (TextBox contains “aa”)
• PreviewKeyDown, Key = A, IsRepeat = True
• KeyDown, Key = A, IsRepeat = True
• PreviewTextInput, Text = a
• (TextBox  contains “aaa”)
• PreviewKeyUp, Key = A, IsRepeat = False
• KeyUp, Key = A, IsRepeat = False