Win32API使用技巧 -- 置頂應用

Win32提供了SetForegroundWindow方法能夠將應用設置到前臺並激活，可是在某些場景下，只調用該接口會返回0，即設置失敗。好比以下場景：

當前前臺應用爲一個全屏的應用，非前臺應用的進程使用Process.Start()方法啓動截圖工具，嘗試使用SetForegroundWindow()將窗口設置到前臺，此時會機率性設置失敗。

嘗試了多種方法後，最終使用以下方法解決了該問題：

public static readonly IntPtr HWND_TOPMOST = new IntPtr(-1);
public static readonly IntPtr HWND_NOTOPMOST = new IntPtr(-2);
public const int SWP_NOSIZE = 0x1;
public const int SWP_NOMOVE = 0x2;

[DllImport("user32.dll")]
public static extern IntPtr GetForegroundWindow();

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

[DllImport("user32.dll")]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

[DllImport("user32.dll")]
public static extern bool SetWindowPos(IntPtr hwnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);

public void StartSnippingTool()
{
    if (!Envronment.Is64BitProcess)
    {
        Process.Start(@"C:\Windows\sysnative\SnippingTool.exe");
    }
    else
    {
        Process.Start(@"C:\Windows\system32\SnippingTool.exe");
    }

    Thread.Sleep(500);
    IntPtr snippingToolHandle = FindWindow("Microsoft-Windows-SnipperToolbar", "截圖工具");
    if (snippingToolHandle != IntPtr.Zero)
    {
        SetForegroundWindowCustom(snippingToolHandle);
    }
}

private void SetForegroundWindowCustom(IntPtr hwnd)
{
    IntPtr currentWindow = GetForegroundWindow();
    if (currentWindow == hwnd)
    {
        Console.WriteLine("應用已在頂層");
        return;
    }

    SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);
    SetWindowPos(hwnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);

    bool result = SetForegroundWindow(hwnd);
    if (result)
    {
        Console.WriteLine("置頂應用成功");
    }
    else
    {
        Console.WriteLine("置頂應用失敗");
    }
}