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How to: Simulate Mouse and Keyboard Events in Code

Windows Forms provides several options for programmatically simulating mouse and keyboard input. This topic provides an overview of these options.

The best way to simulate mouse events is to call the OnEventName method that raises the mouse event you want to simulate. This option is usually possible only within custom controls and forms, because the methods that raise events are protected and cannot be accessed outside the control or form. For example, the following steps illustrate how to simulate clicking the right mouse button in code.

To programmatically click the right mouse button

  1. Create a MouseEventArgs whose Button property is set to the MouseButtons.Right value.

  2. Call the OnMouseClick method with this MouseEventArgs as the argument.

For more information on custom controls, see Developing Windows Forms Controls at Design Time.

There are other ways to simulate mouse input. For example, you can programmatically set a control property that represents a state that is typically set through mouse input (such as the Checked property of the CheckBox control), or you can directly call the delegate that is attached to the event you want to simulate.

Although you can simulate keyboard input by using the strategies discussed above for mouse input, Windows Forms also provides the SendKeys class for sending keystrokes to the active application.

Caution noteCaution

If your application is intended for international use with a variety of keyboards, the use of SendKeys.Send could yield unpredictable results and should be avoided.

NoteNote

The SendKeys class has been updated for the .NET Framework 3.0 to enable its use in applications that run on Windows Vista. The enhanced security of Windows Vista (known as User Account Control or UAC) prevents the previous implementation from working as expected.

The SendKeys class is susceptible to timing issues, which some developers have had to work around. The updated implementation is still susceptible to timing issues, but is slightly faster and may require changes to the workarounds. The SendKeys class tries to use the previous implementation first, and if that fails, uses the new implementation. As a result, the SendKeys class may behave differently on different operating systems. Additionally, when the SendKeys class uses the new implementation, the SendWait method will not wait for messages to be processed when they are sent to another process.

If your application relies on consistent behavior regardless of the operating system, you can force the 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 SendKeys class to use the previous implementation, use the value "JournalHook" instead.

To send a keystroke to the same application

  • Call the Send or SendWait method of the 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 ENTER key when the user double-clicks the surface of the form. This example assumes a Form with a single Button control that has a tab index of 0.

    
    ' Send a key to the button when the user double-clicks anywhere 
    ' on the form.
    Private Sub Form1_DoubleClick(ByVal sender As Object, _
        ByVal e As EventArgs) Handles Me.DoubleClick
    
        ' Send the enter key to the button, which raises the click 
        ' event for the button. This works because the tab stop of 
        ' the button is 0.
        SendKeys.Send("{ENTER}")
    End Sub
    
    
    

To send a keystroke to a different application

  • Activate the application window that will receive the keystrokes, and then call the Send or SendWait method. Because there is no managed method to activate another application, you must use native Windows methods to force focus on other applications. The following code example uses platform invoke to call the FindWindow and SetForegroundWindow methods to activate the Calculator application window, and then calls SendWait to issue a series of calculations to the Calculator application.

    NoteNote

    The correct parameters of the FindWindow call that locates the Calculator application vary based on your version of Windows. The following code finds the Calculator application on Windows 7. On Windows Vista, change the first parameter to "SciCalc". You can use the Spy++ tool, included with Visual Studio, to determine the correct parameters.

    
    ' Get a handle to an application window.
    Declare Auto Function FindWindow Lib "USER32.DLL" ( _
        ByVal lpClassName As String, _
        ByVal lpWindowName As String) As IntPtr
    
    ' Activate an application window.
    Declare Auto Function SetForegroundWindow Lib "USER32.DLL" _
        (ByVal hWnd As IntPtr) As Boolean
    
    ' Send a series of key presses to the Calculator application.
    Private Sub button1_Click(ByVal sender As Object, _
        ByVal e As EventArgs) Handles button1.Click
    
        ' Get a handle to the Calculator application. The window class
        ' and window name were obtained using the Spy++ tool.
        Dim calculatorHandle As IntPtr = FindWindow("CalcFrame", "Calculator")
    
        ' Verify that Calculator is a running process.
        If calculatorHandle = IntPtr.Zero Then
            MsgBox("Calculator is not running.")
            Return
        End If
    
        ' Make Calculator the foreground application and send it 
        ' a set of calculations.
        SetForegroundWindow(calculatorHandle)
        SendKeys.SendWait("111")
        SendKeys.SendWait("*")
        SendKeys.SendWait("11")
        SendKeys.SendWait("=")
    End Sub
    
    
    

The following code example is the complete application for the previous code examples.


Imports System
Imports System.Runtime.InteropServices
Imports System.Drawing
Imports System.Windows.Forms

Namespace SimulateKeyPress

    Class Form1
        Inherits Form
        Private WithEvents button1 As New Button()

        <STAThread()> _
        Public Shared Sub Main()
            Application.EnableVisualStyles()
            Application.Run(New Form1())
        End Sub

        Public Sub New()
            button1.Location = New Point(10, 10)
            button1.TabIndex = 0
            button1.Text = "Click to automate Calculator"
            button1.AutoSize = True
            Me.Controls.Add(button1)
        End Sub

        ' Get a handle to an application window.
        Declare Auto Function FindWindow Lib "USER32.DLL" ( _
            ByVal lpClassName As String, _
            ByVal lpWindowName As String) As IntPtr

        ' Activate an application window.
        Declare Auto Function SetForegroundWindow Lib "USER32.DLL" _
            (ByVal hWnd As IntPtr) As Boolean

        ' Send a series of key presses to the Calculator application.
        Private Sub button1_Click(ByVal sender As Object, _
            ByVal e As EventArgs) Handles button1.Click

            ' Get a handle to the Calculator application. The window class
            ' and window name were obtained using the Spy++ tool.
            Dim calculatorHandle As IntPtr = FindWindow("CalcFrame", "Calculator")

            ' Verify that Calculator is a running process.
            If calculatorHandle = IntPtr.Zero Then
                MsgBox("Calculator is not running.")
                Return
            End If

            ' Make Calculator the foreground application and send it 
            ' a set of calculations.
            SetForegroundWindow(calculatorHandle)
            SendKeys.SendWait("111")
            SendKeys.SendWait("*")
            SendKeys.SendWait("11")
            SendKeys.SendWait("=")
        End Sub

        ' Send a key to the button when the user double-clicks anywhere 
        ' on the form.
        Private Sub Form1_DoubleClick(ByVal sender As Object, _
            ByVal e As EventArgs) Handles Me.DoubleClick

            ' Send the enter key to the button, which raises the click 
            ' event for the button. This works because the tab stop of 
            ' the button is 0.
            SendKeys.Send("{ENTER}")
        End Sub

    End Class
End Namespace


This example requires:

  • References to the System, System.Drawing and System.Windows.Forms assemblies.

For information about building this example from the command line for Visual Basic or Visual C#, see Building from the Command Line (Visual Basic) or Command-line Building With csc.exe. You can also build this example in Visual Studio by pasting the code into a new project. For more information, see How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio and How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio and How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio and How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio and How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio.

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