How to catch Maximize started event using Window Message, etc

Question

I was able to get Maximized and Size changed events, but not Maximize started.

Answer 1

I found solution for my problem. Here is hook method that you can add for your code and do all needed staff before Window Maximized event occurs.

    private static void WmWindowPos(IntPtr hwnd, IntPtr lParam)
    {
        WINDOWPOS wpos = (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));
        IntPtr monitorContainingApplication = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);

        if (monitorContainingApplication == IntPtr.Zero)
            return;

        var monitorInfo = new MONITORINFO();
        GetMonitorInfo(monitorContainingApplication, monitorInfo);
        var rcWorkArea = monitorInfo.rcWork;

        if (wpos.x == rcWorkArea.left &&
            wpos.y == rcWorkArea.top &&
            wpos.cx == rcWorkArea.right &&
            wpos.cy == rcWorkArea.bottom)
        {
            // Do required staff before windows maximized state has changed
        }
    }

Add this method to WindowProc like this

    private static IntPtr WindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        switch (msg)
        {
            case 0x0046: //  WM_WINDOWPOSCHANGING
                WmWindowPos(hwnd, lParam);
                break;
        }

        return (IntPtr)0;
    }