C# Signature:

[DllImport("user32.dll")]
static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint dwData,
   UIntPtr dwExtraInfo);

or

[DllImport("user32.dll")]
static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint dwData,
  int dwExtraInfo);

User-Defined Types:

  [Flags]
  public enum MouseEventTFlags
  {
    LEFTDOWN   = 0x00000002,
    LEFTUP     = 0x00000004,
    MIDDLEDOWN = 0x00000020,
    MIDDLEUP   = 0x00000040,
    MOVE       = 0x00000001,
    ABSOLUTE   = 0x00008000,
    RIGHTDOWN  = 0x00000008,
    RIGHTUP    = 0x00000010
  }

VB.Net Signature:

The declaration as originally posted is incorrect as mouse_event does not return a value. Also, for VB.NET, one should really use Int32 to ensure correct sizing.

Declare Auto Function mouse_event Lib "user32.dll" (ByVal dwflags As Integer, ByVal dx As Integer, ByVal dy As Integer, ByVal dwData As Integer, ByVal dwExtraInfo As Integer) As Integer

Fixed declaration:

Declare Auto Sub mouse_event Lib "user32.dll" (ByVal dwFlags As Int32, ByVal dx As Int32, ByVal dy As Int32, ByVal cButtons As Int32, ByVal dwExtraInfo As Int32)

Notes:

I wanted to emulate the scroll. Searching for this information wasn't easy ... but here is how you do the mouse scroll button

dim ScrollValue as Integer

ScrollValue = 120 'or -120 for up or down scrolling

mouse_event(&H800, 0, 0, ScrollValue, 0)

FYI, Microsoft tells us for "Windows NT/2000/XP: This function has been superseded. Use SendInput instead."

Tips & Tricks:

Please add some!

Sample Code:

C#:

[DllImport("user32.dll")]
static extern bool SetCursorPos(int X, int Y);  

[DllImport("user32.dll")]
static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint dwData,  int dwExtraInfo);

[Flags]
  public enum MouseEventFlags
  {
    LEFTDOWN   = 0x00000002,
    LEFTUP     = 0x00000004,
    MIDDLEDOWN = 0x00000020,
    MIDDLEUP   = 0x00000040,
    MOVE       = 0x00000001,
    ABSOLUTE   = 0x00008000,
    RIGHTDOWN  = 0x00000008,
    RIGHTUP    = 0x00000010
  }
...
//Set cursor position  
SetCursorPos(10, 50);
//Mouse Right Down and Mouse Right Up
mouse_event((uint)MouseEventFlags.RIGHTDOWN,0,0,0,0);
mouse_event((uint)MouseEventFlags.RIGHTUP,0,0,0,0);    

VB.NET 2005:

Taken from http://vb-helper.com/howto_move_click_mouse.html

This code assumes a form called frmMain with a command button called cmdClick a picture box called picClicker and a text box called txtResults

Note Twips are no more. Also, I stripped the FOR loop of delta moves from the command button click to the middle of the picture box.

Option Explicit On

Friend Class frmMain

    Inherits System.Windows.Forms.Form

    Declare Auto Sub mouse_event Lib "user32" (ByVal dwFlags As Int32, ByVal dx As Int32, ByVal dy As Int32, ByVal cButtons As Int32, ByVal dwExtraInfo As Int32)

    Const MOUSEEVENTF_MOVE As Int32 = &H1 '  mouse move
    Const MOUSEEVENTF_LEFTDOWN As Int32 = &H2 '  left button down
    Const MOUSEEVENTF_LEFTUP As Int32 = &H4 '  left button up
    Const MOUSEEVENTF_RIGHTDOWN As Int32 = &H8 '  right button down
    Const MOUSEEVENTF_RIGHTUP As Int32 = &H10 '  right button up
    Const MOUSEEVENTF_MIDDLEDOWN As Int32 = &H20 '  middle button down
    Const MOUSEEVENTF_MIDDLEUP As Int32 = &H40 '  middle button up
    Const MOUSEEVENTF_ABSOLUTE As Int32 = &H8000 '  absolute move
    Const MOUSEEVENTF_WHEEL As Int32 = &H800 ' wheel button rolled

    ' Simulate moving the mouse to the center of the
    ' PictureBox and clicking.
    Private Sub cmdClick_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdClick.Click
    Dim cur_x As Single
    Dim cur_y As Single
    Dim dest_x As Single
    Dim dest_y As Single

    ' mouse_event moves in a coordinate system where
    ' (0, 0) is in the upper left corner and
    ' (65535,65535) is in the lower right corner.

    ' Get the current mouse coordinates and convert
    ' them into this new system.
    cur_x = System.Windows.Forms.Cursor.Position.X * 65535 / System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width
    cur_y = System.Windows.Forms.Cursor.Position.Y * 65535 / System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height

    ' Convert the coordinates of the center of the
    ' picClicker PictureBox into this new system.
    Dim pt As Point = picClicker.PointToScreen(New Point(picClicker.ClientRectangle.Width / 2, picClicker.ClientRectangle.Height / 2))

    dest_x = pt.X * 65535 / System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width
    dest_y = pt.Y * 65535 / System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height

    txtResults.Text = txtResults.Text & "From " & System.Windows.Forms.Cursor.Position.X & " " & System.Windows.Forms.Cursor.Position.Y & " to " & pt.X & " " & pt.Y & vbCrLf
    txtResults.Text = txtResults.Text & "From " & cur_x & " " & cur_y & " to " & dest_x & " " & dest_y & vbCrLf

    ' Move the mouse to its final destination and click it.
    mouse_event(MOUSEEVENTF_ABSOLUTE + MOUSEEVENTF_MOVE + MOUSEEVENTF_LEFTDOWN + MOUSEEVENTF_LEFTUP, dest_x, dest_y, 0, 0)
    End Sub

    Private Sub picClicker_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles picClicker.Click
    txtResults.Text = txtResults.Text & "MouseClick" & vbCrLf
    End Sub

    Private Sub picClicker_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picClicker.MouseDown
    txtResults.Text = txtResults.Text & "MouseDown (" & e.X & ", " & e.Y & ")" & vbCrLf
    End Sub

    Private Sub picClicker_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picClicker.MouseUp
    txtResults.Text = txtResults.Text & "MouseUp (" & e.X & ", " & e.Y & ")" & vbCrLf
    End Sub

End Class

Alternative Managed API:

Do you know one? Please contribute it!

You can use the System.Windows.Froms.Cursor.Position property to set the position of the mouse, if you would like.

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