Changing variables in other applications

Question

Hi i don't know if this is possible. I want to make a C# applications which when is run changes the selected colour in the MsPaint application (which must be running before i run my own application) Is it possible to interact with other applications and chaning their variables?

Alan · Answer

It's not too difficult to interact with other running applications. For example the following C# program will check to see if MSPaint is already running and if it is will force input focus onto it. If MSPaint isn't running it will launch it and wait until it's ready to receive input. It will then send it the keystrokes Alt+FO to open a window so that a file can be selected for viewing or editing: using System; using System.Diagnostics; using System.Runtime.InteropServices; using System.Windows.Forms; class Test { [DllImport(user32.dll)] static extern bool SetForegroundWindow(IntPtr hWnd); static void Main() { Process[] procs = Process.GetProcessesByName(mspaint); // don't use .exe extension here if (procs.Length == 0) { Console.WriteLine(MSPaint was not currently running but an instance has been started); Process proc = new Process(); proc.StartInfo.FileName = mspaint.exe; proc.Start(); proc.WaitForInputIdle(); } else { IntPtr hWnd = procs[0].MainWindowHandle; SetForegroundWindow(hWnd); } SendKeys.SendWait(%FO); } } However MSPaint isn't really designed for automation and AFAIK there are no keyboard shortcuts to select a color. You can send mouse commands to it using either the mouse_event or SendInput() API functions but it's not going to be easy to get the mouse coordinates right to select whichever color you want. However if you want to try here are some links and sample code for P/Invoking these functions from C#. The mouse_event function is deprecated in Win32 programming but is far easier to use than its replacement SendInput: http://www.pinvoke.net/default.aspx/user32/mouse_event.html http://www.pinvoke.net/default.aspx/user32/SendInput.html