docs-desktop/dotnet-desktop-guide/net/winforms/input-keyboard/how-to-simulate-events.md

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title	description	ms.date	dev_langs	helpviewer_keywords
Simulate keyboard events	Learn how to simulate keyboard events in Windows Forms for .NET.	10/26/2020	csharp vb	keyboards [Windows Forms], event simulation user input [Windows Forms], simulating SendKeys [Windows Forms], using

How to simulate keyboard events (Windows Forms .NET)

Windows Forms provides a few options for programmatically simulating keyboard input. This article provides an overview of these options.

[!INCLUDE desktop guide under construction]

Use SendKeys

Windows Forms provides the xref:System.Windows.Forms.SendKeys?displayProperty=fullName class for sending keystrokes to the active application. There are two methods to send keystrokes to an application: xref:System.Windows.Forms.SendKeys.Send%2A?displayProperty=nameWithType and xref:System.Windows.Forms.SendKeys.SendWait%2A?displayProperty=nameWithType. The difference between the two methods is that SendWait blocks the current thread when the keystroke is sent, waiting for a response, while Send doesn't. For more information about SendWait, see To send a keystroke to a different application.

Caution

If your application is intended for international use with a variety of keyboards, the use of xref:System.Windows.Forms.SendKeys.Send%2A?displayProperty=nameWithType could yield unpredictable results and should be avoided.

Behind the scenes, SendKeys uses an older Windows implementation for sending input, which may fail on modern Windows where it's expected that the application isn't running with administrative rights. If the older implementation fails, the code automatically tries the newer Windows implementation for sending input. Additionally, when the xref:System.Windows.Forms.SendKeys class uses the new implementation, the xref:System.Windows.Forms.SendKeys.SendWait%2A method no longer blocks the current thread when sending keystrokes to another application.

Important

If your application relies on consistent behavior regardless of the operating system, you can force the xref:System.Windows.Forms.SendKeys class to use the new implementation by adding the following application setting to your app.config file.

<appSettings>
  <add key="SendKeys" value="SendInput"/>
</appSettings>

To force the xref:System.Windows.Forms.SendKeys class to only use the previous implementation, use the value "JournalHook" instead.

To send a keystroke to the same application

Call the xref:System.Windows.Forms.SendKeys.Send%2A?displayProperty=nameWithType or xref:System.Windows.Forms.SendKeys.SendWait%2A?displayProperty=nameWithType method of the xref:System.Windows.Forms.SendKeys class. The specified keystrokes will be received by the active control of the application.

The following code example uses Send to simulate pressing the ALT and DOWN keys together. These keystrokes cause the xref:System.Windows.Forms.ComboBox control to display its dropdown. This example assumes a xref:System.Windows.Forms.Form with a xref:System.Windows.Forms.Button and xref:System.Windows.Forms.ComboBox.

:::code language="csharp" source="snippets/how-to-simulate-events/csharp/Form1.cs" id="ShowDropDown"::: :::code language="vb" source="snippets/how-to-simulate-events/vb/Form1.vb" id="ShowDropDown":::

To send a keystroke to a different application

The xref:System.Windows.Forms.SendKeys.Send%2A?displayProperty=nameWithType and xref:System.Windows.Forms.SendKeys.SendWait%2A?displayProperty=nameWithType methods send keystrokes to the active application, which is usually the application you're sending keystrokes from. To send keystrokes to another application, you first need to activate it. Because there's no managed method to activate another application, you must use native Windows methods to focus the other application. The following code example uses platform invoke to call the FindWindow and SetForegroundWindow methods to activate the Calculator application window, and then calls Send to issue a series of calculations to the Calculator application.

The following code example uses Send to simulate pressing keys into the Windows 10 Calculator application. It first searches for an application window with title of Calculator and then activates it. Once activated, the keystrokes are sent to calculate 10 plus 10.

:::code language="csharp" source="snippets/how-to-simulate-events/csharp/Form2.cs" id="Calculator"::: :::code language="vb" source="snippets/how-to-simulate-events/vb/Form2.vb" id="Calculator":::

Use OnEventName methods

The easiest way to simulate keyboard events is to call a method on the object that raises the event. Most events have a corresponding method that invokes them, named in the pattern of On followed by EventName, such as OnKeyPress. This option is only possible within custom controls or forms, because these methods are protected and can't be accessed from outside the context of the control or form.

These protected methods are available to simulate keyboard events.

• OnKeyDown
• OnKeyPress
• OnKeyUp

For more information about these events, see Using keyboard events (Windows Forms .NET).

See also

• Overview of using the keyboard (Windows Forms .NET)
• Using keyboard events (Windows Forms .NET)
• Using mouse events (Windows Forms .NET)
• xref:System.Windows.Forms.SendKeys
• xref:System.Windows.Forms.Keys
• xref:System.Windows.Forms.Control.KeyDown
• xref:System.Windows.Forms.Control.KeyPress