Question

I need to get an input point (caret position, window/control) that is focused. My application/service needs to detect when the user starts typing and then replace the characters that were typed with predetermined values. The trick is that I don’t know where the user wants to type(I don’t want to limit this to several applications).

I think that I know how to get/replace the text using:

[DllImport("USER32.DLL", CharSet = CharSet.Auto)]
public static extern IntPtr SendMessage(IntPtr hWnd, uint msg, IntPtr wparam, StringBuilder text);

How do I get the control that is focused? How do I know from where to get the text and where to send the replacement?

I am doing this in C#, WPF.

Thank you!

Answer 1

I am presuming that since you have tagged your question as WinAPI your are trying to intercept keystrokes from another application as in Keyboard Hooking. Take a look at these Links:

• Intercepting and Blocking Keystrokes
• How do I set a low level mouse hook and keyboard hook in C#?
• How to set a Windows hook in Visual C# .NET
• A Simple C# Global Low Level Keyboard Hook