Question

I want to do an app which replaces every input if it matches a pattern.
For example if user press LeftMouseButton + Ctrl, the program will change it into right click, and send only that to the current active window, or capturing window.

The question is how can i solve it in c#?

Answer 1

You will need to implement a class like this, you have to adapt it to support mouse clicks to fulfill your needs, but it should show you some first steps.

public class KeyConverter {
            //All conversions are stored in this dictionary.
    private Dictionary<Keys, Keys> conversions = new Dictionary<Keys, Keys>();

    public KeyConverter() {
        //this conversion will convert every Ctrl+C signal into Ctrl+V
        conversions.Add(Keys.C | Keys.Control, Keys.V | Keys.Control);
    }

    public Keys Convert(Keys keys) {
        if (conversions.ContainsKey(keys))
            return conversions[keys];
        else
            return keys;  //return the input if no conversion is available
    }
}

Add the conversion you need to the conversions-Dictionary. Subscribe to an event that observes key strokes and call method Convert with currently pressed Keys.
Send the returned keys to your system using

[DllImport("user32.dll")]
public static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, uint dwExtraInfo);

public void SendKey(Keys keys){
    foreach(Keys key in Enum.GetValues(typeof(Keys)))
        if(keys.HasFlag(key))
            keybd_event((byte)key, 0, 0, 0); //press key
    foreach(Keys key in Enum.GetValues(typeof(Keys)))
        if(keys.HasFlag(key))
            keybd_event((byte)key, 0, 0x2, 0); // release key
}