如何从其 Win32 句柄获取 System.Windows.Form 实例？

发布于 2024-07-13 22:30:50 字数 1619 浏览 6 评论 0原文

以下代码实现了一个简单的单例，确保我的应用程序只能运行 1 个实例。但是，如果启动另一个实例，我需要能够获取该实例的命令行参数，将它们传递给初始实例，然后终止第二个实例。

当我尝试获取应用程序的第一个实例时，问题就出现了。找到该实例的主窗体的句柄后，我将其传递给 Control.FromHandle() 方法，期望返回 MainForm。相反，返回值始终为 null。（Control.FromChildHandle() 给出相同的结果。）

因此，我的问题很简单：我做错了什么？这在 .NET 中可能吗？

public class MainForm : Form
{
[DllImport("user32")]
extern static int ShowWindowAsync(IntPtr hWnd, int nCmdShow);

[DllImport("user32")]
extern static bool SetForegroundWindow(IntPtr hWnd);

private Mutex singletonMutex;

private void MainForm_Load(object sender, EventArgs e)
{
  bool wasCreated;
  singletonMutex = new Mutex(false, Application.ProductName + "Mutex", out wasCreated);

  // returns false for every instance except the first
  if (!wasCreated)
  {
    Process thisProcess = Process.GetCurrentProcess();
    Process[] peerProcesses = Process.GetProcessesByName(thisProcess.ProcessName.Replace(".vshost", string.Empty));

    foreach (Process currentProcess in peerProcesses)
    {
      if (currentProcess.Handle != thisProcess.Handle)
      {
        ShowWindowAsync(currentProcess.MainWindowHandle, 1); // SW_NORMAL
        SetForegroundWindow(currentProcess.MainWindowHandle);

        // always returns null !!!
        MainForm runningForm = (MainForm) Control.FromHandle(currentProcess.MainWindowHandle);

        if (runningForm != null)
        {
          runningForm.Arguments = this.Arguments;
          runningForm.ProcessArguments();
        }

        break;
      }
    }

    Application.Exit();

    return;
  }
}

原文

The following code implements a simple singleton that ensures only 1 instance of my application can be run. However, if another instance is started, I need to be able to grab that instance's command-line arguments, pass them to the initial instance, then terminate the second instance.

The issue comes in when I'm attempting to get hold of the first instance of the application. Once I've found the handle of that instance's main form, I pass it to the Control.FromHandle() method, expecting to get back a MainForm. Instead, the return value is always null. (Control.FromChildHandle() gives the same result.)

Therefore, my question is simply: what am I doing wrong? And is this even possible in .NET?

public class MainForm : Form
{
[DllImport("user32")]
extern static int ShowWindowAsync(IntPtr hWnd, int nCmdShow);

[DllImport("user32")]
extern static bool SetForegroundWindow(IntPtr hWnd);

private Mutex singletonMutex;

private void MainForm_Load(object sender, EventArgs e)
{
  bool wasCreated;
  singletonMutex = new Mutex(false, Application.ProductName + "Mutex", out wasCreated);

  // returns false for every instance except the first
  if (!wasCreated)
  {
    Process thisProcess = Process.GetCurrentProcess();
    Process[] peerProcesses = Process.GetProcessesByName(thisProcess.ProcessName.Replace(".vshost", string.Empty));

    foreach (Process currentProcess in peerProcesses)
    {
      if (currentProcess.Handle != thisProcess.Handle)
      {
        ShowWindowAsync(currentProcess.MainWindowHandle, 1); // SW_NORMAL
        SetForegroundWindow(currentProcess.MainWindowHandle);

        // always returns null !!!
        MainForm runningForm = (MainForm) Control.FromHandle(currentProcess.MainWindowHandle);

        if (runningForm != null)
        {
          runningForm.Arguments = this.Arguments;
          runningForm.ProcessArguments();
        }

        break;
      }
    }

    Application.Exit();

    return;
  }
}

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酒绊 2024-07-20 22:30:50

.NET 框架很好地支持单实例应用程序。检查此线程的示例完全符合您的需要。

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七月上 2024-07-20 22:30:50

尝试以下

var form = (Form)(Control.FromHandle(myHandle));

编辑

重新阅读您的问题，并意识到您正在另一个进程中查看句柄。无法将另一个进程中的句柄转换为当前进程中的 Form 实例。我的解决方案仅适用于同一进程中的句柄。

获取 Form 实例的唯一方法是使用 Remoting。但这需要两个过程的合作，这似乎不是您所寻求的。

Try the following

var form = (Form)(Control.FromHandle(myHandle));

EDIT

Re-read your question and realized you are looking at a handle in another process. There is no way to convert a handle in another process to a Form instance in the current process. My solution will only work for handles in the same process.

The only way to get ahold of the Form instance is to use Remoting. But that will require cooperation on the part of both processes which does not appear to be what you are looking for.

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