Hello all! I am trying to use SendMessage to fake a mouse click in another application. This is the code I have so far. It takes the Window Caption and/or class name of the target window, gets its HWND and Client Rect (that part works fine) then uses SendMessage to send a mouse click. When I run this I get no errors and both calls to SendMessage return 0. However, the Click event on the target form (for now I am just targeting a small dummy app I wrote to test this) does not fire. Any suggestions?
Code:
public const uint WM_LBUTTONDOWN = 0x201;
public const uint WM_LBUTTONUP = 0x202;
[DllImport("user32.dll", EntryPoint = "SendMessageW")]
public static extern uint SendMessage(uint Handle, uint wMsg, uint wParam, uint lParam);
[DllImport("user32.dll", EntryPoint = "FindWindowW")]
public static extern uint FindWindow(IntPtr lpClassName,IntPtr lpWindowName);
[DllImport("user32.dll", EntryPoint = "GetClientRect")]
public static extern bool GetClientRect(uint hWnd,ref RECT lpRect);
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int left;
public int top;
public int right;
public int bottom;
}
private uint PackMessage(Int16 High,Int16 Low)
{
return((uint)((High * 0x10000) + Low));
}
private void cmdSendClick_Click(object sender, System.EventArgs e)
{
IntPtr ptrCaption,ptrClass;
uint hWnd=0;
if(txtCaption.Text == "")
{
ptrCaption = IntPtr.Zero;
}
else
{
ptrCaption = Marshal.StringToHGlobalUni(txtCaption.Text);
}
if(txtClass.Text == "")
{
ptrClass = IntPtr.Zero;
}
else
{
ptrClass = Marshal.StringToHGlobalUni(txtClass.Text);
}
hWnd = FindWindow(ptrClass,ptrCaption);
if(txtCaption.Text != "")
{
Marshal.FreeCoTaskMem(ptrCaption);
}
if(txtClass.Text != "")
{
Marshal.FreeCoTaskMem(ptrClass)
}
if(hWnd == 0)
{
lblResult.Text = "Window not found";
return;
}
RECT ClientRect = new RECT();
GetClientRect(hWnd,ref ClientRect);
lblResult.Text = SendMessage(hWnd, WM_LBUTTONDOWN, 0, PackMessage((Int16)(ClientRect.bottom/2),(Int16)(ClientRect.right/2))).ToString();
Application.DoEvents();
lblResult.Text = lblResult.Text + " " + SendMessage(hWnd, WM_LBUTTONUP, 0, PackMessage((Int16)(ClientRect.bottom/2),(Int16)(ClientRect.right/2))).ToString();
Application.DoEvents();
}
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