How do I center a window onscreen in C#?

Question

I need a way to center the current window. So for example, if a user pushes a button, I want the window to center itself onscreen. I know you can use the startposition prope

Answer 1

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace centrewindow
{
    public partial class Form1 : Form
    {
        public struct RECT
        {
            public int Left;        // x position of upper-left corner
            public int Top;         // y position of upper-left corner
            public int Right;       // x position of lower-right corner
            public int Bottom;      // y position of lower-right corner
        }

        [DllImport("user32.dll")]
        public static extern IntPtr SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int Y, int cx, int cy, int wFlags);

        [DllImport("user32.dll")]
        public static extern bool GetWindowRect(HandleRef hwnd, out RECT lpRect);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            CentreWindow(Handle, GetMonitorDimensions());
        }

        private void CentreWindow(IntPtr handle, Size monitorDimensions)
        {
            RECT rect;
            GetWindowRect(new HandleRef(this, handle), out rect);

            var x1Pos = monitorDimensions.Width/2 - (rect.Right - rect.Left)/2;
            var x2Pos = rect.Right - rect.Left;
            var y1Pos = monitorDimensions.Height/2 - (rect.Bottom - rect.Top)/2;
            var y2Pos = rect.Bottom - rect.Top;

            SetWindowPos(handle, 0, x1Pos, y1Pos, x2Pos, y2Pos, 0);
        }

        private Size GetMonitorDimensions()
        {
            return SystemInformation.PrimaryMonitorSize;
        }
    }
}

Centers any window you can get the handle of