c# - 底层表单消失但仅当对话框显示时

Question

这与通过互操作显示 C# 表单的 VB6 应用程序相关。

C# 表单中的事件导致显示 VB6 应用程序表单之一。

通常，当隐藏此 VB6 表单 (Form.Hide) 时，底层 C# 表单会显示在前面。

但是，如果 VB6 窗体在其生命周期内导致 MsgBox 显示，那么当 VB6 窗体隐藏时，底层 C# 窗体将不会位于前面。

为什么会发生这种情况？就像 MsgBox 正在更改表单的 Z 顺序。

Answer 1

“如何在隐藏 VB6 后显示 C# 窗体？我必须使用窗口句柄吗？”

假设您同意孤立的消息框保持打开状态。当 VB6 窗体隐藏时，您需要触发一个事件来获取窗口句柄:

public static int FindWindow(string windowName, bool wait)
{
    int hWnd = FindWindow(null, windowName);
    while (wait && hWnd == 0)
    {
         System.Threading.Thread.Sleep(500);
         hWnd = FindWindow(null, windowName);
    }

    return hWnd;
}

然后将 C# 窗口置于顶部:

[DllImport("user32.dll", SetLastError = true)]
public static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

// When you don't want the ProcessId, use this overload and pass IntPtr.Zero for the second parameter
[DllImport("user32.dll")]
public static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId);

[DllImport("kernel32.dll")]
public static extern uint GetCurrentThreadId();

/// <summary>The GetForegroundWindow function returns a handle to the foreground window.</summary>
[DllImport("user32.dll")]
public static extern IntPtr GetForegroundWindow();

[DllImport("user32.dll")]
public static extern bool AttachThreadInput(uint idAttach, uint idAttachTo, bool fAttach);

[DllImport("user32.dll", SetLastError = true)]
public static extern bool BringWindowToTop(IntPtr hWnd);

[DllImport("user32.dll", SetLastError = true)]
public static extern bool BringWindowToTop(HandleRef hWnd);

[DllImport("user32.dll")]
public static extern bool ShowWindow(IntPtr hWnd, uint nCmdShow);

private static void ForceForegroundWindow(IntPtr hWnd)
{
    uint foreThread = GetWindowThreadProcessId(GetForegroundWindow(), IntPtr.Zero);
    uint appThread = GetCurrentThreadId();
    const uint SW_SHOW = 5;

    if (foreThread != appThread)
    {
        AttachThreadInput(foreThread, appThread, true);
        BringWindowToTop(hWnd);
        ShowWindow(hWnd, SW_SHOW);
        AttachThreadInput(foreThread, appThread, false);
    }
    else
    {
        BringWindowToTop(hWnd);
        ShowWindow(hWnd, SW_SHOW);
    }
}

引用号:SetForegroundWindow Win32-API not always works on Windows-7