How to get and set the window position of another application in C#

Question

How can I get and set the position of another application using C#?

For example, I would like to get the top left hand coordinates of Notepad (let’s say it's floating somewhere at 100,400) and the position this window at 0,0.

What's the easiest way to achieve this?

Answer 1

I actually wrote an open source DLL just for this sort of thing. Download Here

This will allow you to find, enumerate, resize, reposition, or do whatever you want to other application windows and their controls. There is also added functionality to read and write the values/text of the windows/controls and do click events on them. It was basically written to do screen scraping with - but all the source code is included so everything you want to do with the windows is included there.

Answer 2

David's helpful answer provides the crucial pointers and helpful links.

To put them to use in a self-contained example that implements the sample scenario in the question, using the Windows API via P/Invoke (System.Windows.Forms is not involved):

using System;
using System.Runtime.InteropServices; // For the P/Invoke signatures.

public static class PositionWindowDemo
{

    // P/Invoke declarations.

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    [DllImport("user32.dll", SetLastError = true)]
    static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

    const uint SWP_NOSIZE = 0x0001;
    const uint SWP_NOZORDER = 0x0004;

    public static void Main()
    {
        // Find (the first-in-Z-order) Notepad window.
        IntPtr hWnd = FindWindow("Notepad", null);

        // If found, position it.
        if (hWnd != IntPtr.Zero)
        {
            // Move the window to (0,0) without changing its size or position
            // in the Z order.
            SetWindowPos(hWnd, IntPtr.Zero, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOZORDER);
        }
    }

}

Answer 3

Try using FindWindow (signature) to get the HWND of the target window. Then you can use SetWindowPos (signature) to move it.

Answer 4

You will need to use som P/Invoke interop to achieve this. The basic idea would be to find the window first (for instance, using the EnumWindows function), and then getting the window position with GetWindowRect.