如何使任务栏在失去焦点时闪烁

Question

我偶然发现了下面的代码，并尝试在我的WinForm应用程序中实现它，以帮助那些不太懂技术的用户。

不幸的是，它什么都没做。它既没有生成任何错误，也没有闪烁。能否有人提供任何见解？我已经在Win 7(x64)和Win XP(x86)上尝试过，结果都相同。

我像这样调用它 --> TaskbarFlasher.FlashWindow(this); 从我的主窗体。

[DllImport("user32.dll")]
    private extern static bool FlashWindow(IntPtr hwnd, bool bInvert);
    [DllImport("user32.dll")]
    private extern static IntPtr GetForegroundWindow();

    /// <summary>
    /// Notifies the user that the application requests attention
    /// by flashing the taskbar if the form is not the current window.
    /// </summary>
    /// <param name="myForm">The form in question.</param>
    public static void FlashWindow(Form myForm)
    {
        // if the current foreground window isn't this window,
        // flash this window in task bar once every 1 second
        if (GetForegroundWindow() != myForm.Handle)
        {
            FlashWindow(myForm.Handle, true);
        }
    }

- Refracted Paladin

---

你为什么想要对那些从你的应用程序点击到邮件客户端或病毒扫描器的可怜用户释放尖叫闪烁的死亡呢？ :D - Robert P

实际上，我需要它来帮助他们看到它已经打开，否则他们会尝试运行多个数据输入应用程序实例... - Refracted Paladin

那么你真正想要做的是确保应用程序的单一实例，这是另一种问题。请不要滥用（并且真正破坏）Windows UI指南，使用失去焦点通知来实现此目的。请不要按照你计划的方式做。 - Clinton Pierce

我正在防止多个实例，但我仍然需要一些方法来引导它们到现有的实例。正如我所说，我们公司的用户非常不熟练。顺便提一句；MSN Messenger 是否有时在任务栏中闪烁？我当然不是在推荐它，但它似乎在我这种情况下填补了一个需求。你们两个有其他的建议吗？谢谢。 - Refracted Paladin

我有一个类似的情况：我正在使用互斥锁来检查实例是否唯一，如果不是，则使用IPC向现有客户端发送消息，以便激活并显示它自己。 - Jeff B

Answer 1

没关系，我通过下面的链接找到了答案--> http://pietschsoft.com/post/2009/01/26/CSharp-Flash-Window-in-Taskbar-via-Win32-FlashWindowEx.aspx

感谢来自同为SO（Stack Overflow）的Chris Pietschmann，我来自威斯康星州！

public static class FlashWindow
{
    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool FlashWindowEx(ref FLASHWINFO pwfi);
    [StructLayout(LayoutKind.Sequential)]
    private struct FLASHWINFO
    {
        /// <summary>
        /// The size of the structure in bytes.
        /// </summary>
        public uint cbSize;
        /// <summary>
        /// A Handle to the Window to be Flashed. The window can be either opened or minimized.
        /// </summary>
        public IntPtr hwnd;
        /// <summary>
        /// The Flash Status.
        /// </summary>
        public uint dwFlags;
        /// <summary>
        /// The number of times to Flash the window.
        /// </summary>
        public uint uCount;
        /// <summary>
        /// The rate at which the Window is to be flashed, in milliseconds. If Zero, the function uses the default cursor blink rate.
        /// </summary>
        public uint dwTimeout;
    }
    /// <summary>
    /// Stop flashing. The system restores the window to its original stae.
    /// </summary>
    public const uint FLASHW_STOP = 0;

    /// <summary>
    /// Flash the window caption.
    /// </summary>
    public const uint FLASHW_CAPTION = 1;

    /// <summary>
    /// Flash the taskbar button.
    /// </summary>
    public const uint FLASHW_TRAY = 2;

    /// <summary>
    /// Flash both the window caption and taskbar button.
    /// This is equivalent to setting the FLASHW_CAPTION | FLASHW_TRAY flags.
    /// </summary>
    public const uint FLASHW_ALL = 3;
    /// <summary>
    /// Flash continuously, until the FLASHW_STOP flag is set.
    /// </summary>
    public const uint FLASHW_TIMER = 4;
    /// <summary>
    /// Flash continuously until the window comes to the foreground.
    /// </summary>
    public const uint FLASHW_TIMERNOFG = 12;

    /// <summary>
    /// Flash the spacified Window (Form) until it recieves focus.
    /// </summary>
    /// <param name="form">The Form (Window) to Flash.</param>
    /// <returns></returns>
    public static bool Flash(System.Windows.Forms.Form form)
    {
        // Make sure we're running under Windows 2000 or later
        if (Win2000OrLater)
        {
            FLASHWINFO fi = Create_FLASHWINFO(form.Handle, FLASHW_ALL | FLASHW_TIMERNOFG, uint.MaxValue, 0);
            return FlashWindowEx(ref fi);
        }
        return false;
    }
    private static FLASHWINFO Create_FLASHWINFO(IntPtr handle, uint flags, uint count, uint timeout)
    {
        FLASHWINFO fi = new FLASHWINFO();
        fi.cbSize = Convert.ToUInt32(Marshal.SizeOf(fi));
        fi.hwnd = handle;
        fi.dwFlags = flags;
        fi.uCount = count;
        fi.dwTimeout = timeout;
        return fi;
    }
    /// <summary>
    /// Flash the specified Window (form) for the specified number of times
    /// </summary>
    /// <param name="form">The Form (Window) to Flash.</param>
    /// <param name="count">The number of times to Flash.</param>
    /// <returns></returns>
    public static bool Flash(System.Windows.Forms.Form form, uint count)
    {
        if (Win2000OrLater)
        {
            FLASHWINFO fi = Create_FLASHWINFO(form.Handle, FLASHW_ALL, count, 0);
            return FlashWindowEx(ref fi);
        }
        return false;
    }
    /// <summary>
    /// Start Flashing the specified Window (form)
    /// </summary>
    /// <param name="form">The Form (Window) to Flash.</param>
    /// <returns></returns>
    public static bool Start(System.Windows.Forms.Form form)
    {
        if (Win2000OrLater)
        {
            FLASHWINFO fi = Create_FLASHWINFO(form.Handle, FLASHW_ALL, uint.MaxValue, 0);
            return FlashWindowEx(ref fi);
        }
        return false;
    }
    /// <summary>
    /// Stop Flashing the specified Window (form)
    /// </summary>
    /// <param name="form"></param>
    /// <returns></returns>
    public static bool Stop(System.Windows.Forms.Form form)
    {
        if (Win2000OrLater)
        {
            FLASHWINFO fi = Create_FLASHWINFO(form.Handle, FLASHW_STOP, uint.MaxValue, 0);
            return FlashWindowEx(ref fi);
        }
        return false;
    }
    /// <summary>
    /// A boolean value indicating whether the application is running on Windows 2000 or later.
    /// </summary>
    private static bool Win2000OrLater
    {
        get { return System.Environment.OSVersion.Version.Major >= 5; }
    }
}

- Refracted Paladin