Example of SendKeyEvent for CefSharp.OffScreen

SendKeyEventExample.cs

        [DllImport("user32.dll")]
        public static extern int ToUnicode(uint virtualKeyCode, uint scanCode,
            byte[] keyboardState,
            [Out, MarshalAs(UnmanagedType.LPWStr, SizeConst = 64)]
            StringBuilder receivingBuffer,
            int bufferSize, uint flags);

        /// <summary>
        /// https://stackoverflow.com/a/6949520/450141
        /// </summary>
        static string GetCharsFromKeys(Keys keys, bool shift, bool altGr)
        {
            var buf = new StringBuilder(256);
            var keyboardState = new byte[256];
            if (shift)
                keyboardState[(int)Keys.ShiftKey] = 0xff;
            if (altGr) {
                keyboardState[(int)Keys.ControlKey] = 0xff;
                keyboardState[(int)Keys.Menu] = 0xff;
            }
            ToUnicode((uint)keys, 0, keyboardState, buf, 256, 0);
            return buf.ToString();
        }

        static void SendKeys(ChromiumWebBrowser browser)
        {
            KeyEvent[] events = new KeyEvent[] {
                new KeyEvent() { FocusOnEditableField = true, WindowsKeyCode = GetCharsFromKeys(Keys.R, false, false)[0], Modifiers = CefEventFlags.None, Type = KeyEventType.Char, IsSystemKey = false }, // Just the letter R, no shift (so no caps...?)
                new KeyEvent() { FocusOnEditableField = true, WindowsKeyCode = GetCharsFromKeys(Keys.R, true, false)[0], Modifiers = CefEventFlags.ShiftDown, Type = KeyEventType.Char, IsSystemKey = false }, // Capital R?
                new KeyEvent() { FocusOnEditableField = true, WindowsKeyCode = GetCharsFromKeys(Keys.D4, false, false)[0], Modifiers = CefEventFlags.None, Type = KeyEventType.Char, IsSystemKey = false }, // Just the number 4
                new KeyEvent() { FocusOnEditableField = true, WindowsKeyCode = GetCharsFromKeys(Keys.D4, true, false)[0], Modifiers = CefEventFlags.ShiftDown, Type = KeyEventType.Char, IsSystemKey = false }, // Shift 4 (should be $)
            };

            foreach (KeyEvent ev in events) {
                Thread.Sleep(100);
                browser.GetBrowser().GetHost().SendKeyEvent(ev);
            }
        }