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

public static class TaskbarProgress
{
    public enum TaskbarStates
    {
        NoProgress = 0,
        Indeterminate = 0x1,
        Normal = 0x2,
        Error = 0x4,
        Paused = 0x8
    }

    [ComImportAttribute()]
    [GuidAttribute("ea1afb91-9e28-4b86-90e9-9e9f8a5eefaf")]
    [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
    private interface ITaskbarList3
    {
        // ITaskbarList
        [PreserveSig]
        void HrInit();
        [PreserveSig]
        void AddTab(IntPtr hwnd);
        [PreserveSig]
        void DeleteTab(IntPtr hwnd);
        [PreserveSig]
        void ActivateTab(IntPtr hwnd);
        [PreserveSig]
        void SetActiveAlt(IntPtr hwnd);

        // ITaskbarList2
        [PreserveSig]
        void MarkFullscreenWindow(IntPtr hwnd, [MarshalAs(UnmanagedType.Bool)] bool fFullscreen);

        // ITaskbarList3
        [PreserveSig]
        void SetProgressValue(IntPtr hwnd, UInt64 ullCompleted, UInt64 ullTotal);
        [PreserveSig]
        void SetProgressState(IntPtr hwnd, TaskbarStates state);
    }

    [GuidAttribute("56FDF344-FD6D-11d0-958A-006097C9A090")]
    [ClassInterfaceAttribute(ClassInterfaceType.None)]
    [ComImportAttribute()]
    private class TaskbarInstance
    {
    }

    private static bool taskbarSupported = Environment.OSVersion.Version >= new Version(6, 1);

    public static void SetState(Form form, TaskbarStates taskbarState)
    {
        if (taskbarSupported)
        {
                var taskbarInstance = (ITaskbarList3)new TaskbarInstance();
            taskbarInstance.SetProgressState(form.Handle, taskbarState);
        }
    }

    public static void SetValue(Form form, double progressValue, double progressMax)
    {
        if (taskbarSupported)
        {
            var taskbarInstance = (ITaskbarList3)new TaskbarInstance();
            taskbarInstance.SetProgressValue(form.Handle, (ulong)progressValue, (ulong)progressMax);
        }
    }
}