Need to refresh chrome browser using C#

Question

In my windows application on button click, I need to refresh all opened Chrome browser instances or at least the Active tab on my machine.

My code below:

 [DllImport("user32.dll")]
 static extern bool PostMessage(IntPtr hWnd, UInt32 Msg, int wParam, int lParam);
 private void btnGetBrowserProcess_Click(object sender, EventArgs e)
    {
       const UInt32 WM_KEYDOWN = 0x0100;
       const int VK_F5 = 0x74;

        Process[] procsChrome = Process.GetProcessesByName("chrome");
        foreach (Process chrome in procsChrome)
        {
            if (chrome.MainWindowHandle != IntPtr.Zero)
            {
               PostMessage(chrome.MainWindowHandle, WM_KEYDOWN, VK_F5, 0);
            }
        }
}

This works fine with IE and Mozilla but doesn't work with Chrome

Answer 1

Try using SendInput command instead. Unfortunately that means you need to add bit more code to set things up and you will also need to set focus on the chrome window before the keypress can be sent.

The two required external functions are:

    [DllImport("user32.dll")]
    static extern bool SetForegroundWindow(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern uint SendInput(uint numberOfInputs, INPUT[] inputs, int sizeOfInputStructure);

Then the required structs are:

    /// <summary>
    /// http://msdn.microsoft.com/en-us/library/windows/desktop/ms646270(v=vs.85).aspx
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    internal struct INPUT
    {
        public uint Type;
        public MOUSEKEYBDHARDWAREINPUT Data;
    }

    /// <summary>
    /// http://social.msdn.microsoft.com/Forums/en/csharplanguage/thread/f0e82d6e-4999-4d22-b3d3-32b25f61fb2a
    /// </summary>
    [StructLayout(LayoutKind.Explicit)]
    internal struct MOUSEKEYBDHARDWAREINPUT
    {
        [FieldOffset(0)]
        public HARDWAREINPUT Hardware;
        [FieldOffset(0)]
        public KEYBDINPUT Keyboard;
        [FieldOffset(0)]
        public MOUSEINPUT Mouse;
    }

    /// <summary>
    /// http://msdn.microsoft.com/en-us/library/windows/desktop/ms646310(v=vs.85).aspx
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    internal struct HARDWAREINPUT
    {
        public uint Msg;
        public ushort ParamL;
        public ushort ParamH;
    }

    /// <summary>
    /// http://msdn.microsoft.com/en-us/library/windows/desktop/ms646310(v=vs.85).aspx
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    internal struct KEYBDINPUT
    {
        public ushort Vk;
        public ushort Scan;
        public uint Flags;
        public uint Time;
        public IntPtr ExtraInfo;
    }

    /// <summary>
    /// http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/2abc6be8-c593-4686-93d2-89785232dacd
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    internal struct MOUSEINPUT
    {
        public int X;
        public int Y;
        public uint MouseData;
        public uint Flags;
        public uint Time;
        public IntPtr ExtraInfo;
    }

Then finally change your click event as such:

private void btnGetBrowserProcess_Click(object sender, EventArgs e)
{
        Process[] procsChrome = Process.GetProcessesByName("chrome");
        foreach (Process chrome in procsChrome)
        {
            if (chrome.MainWindowHandle != IntPtr.Zero)
            {
                // Set focus on the window so that the key input can be received.
                SetForegroundWindow(chrome.MainWindowHandle);

                // Create a F5 key press
                INPUT ip = new INPUT { Type  =1};
                ip.Data.Keyboard = new KEYBDINPUT();
                ip.Data.Keyboard.Vk = (ushort)0x74;  // F5 Key
                ip.Data.Keyboard.Scan = 0;
                ip.Data.Keyboard.Flags = 0;
                ip.Data.Keyboard.Time = 0;
                ip.Data.Keyboard.ExtraInfo = IntPtr.Zero;

                var inputs = new INPUT[] { ip };

                // Send the keypress to the window
                SendInput(1, inputs, Marshal.SizeOf(typeof(INPUT)));

                // probably need to set focus back to your application here.
            }
        }
}

I've tried this out for myself and the current Chrome tab that I had opened refreshed successfully. I built this example using the following as references:

• http://batchloaf.wordpress.com/2012/04/17/simulating-a-keystroke-in-win32-c-or-c-using-sendinput/
• Send keys through SendInput in user32.dll

Unfortunately I don't have an explanation as to why PostMessage is not working for Chrome, but I suspect it will have something to do with the way in which it has been built.