How to Enumerate Windows Associated with a Process in .NET

Problem Description

The task is to identify and list all windows created by a specific process using the .NET framework. By providing the process ID (PID), this task seeks an effective way to enumerate all corresponding windows.

Solution

To achieve this in .NET, a combination of the EnumThreadWindows and GetProcessById functions can be employed. The following code snippet demonstrates how to implement this solution:

delegate bool EnumThreadDelegate(IntPtr hWnd, IntPtr lParam);

[DllImport("user32.dll")]
static extern bool EnumThreadWindows(int dwThreadId, EnumThreadDelegate lpfn,
    IntPtr lParam);

static IEnumerable EnumerateProcessWindowHandles(int processId)
{
    var handles = new List();

    foreach (ProcessThread thread in Process.GetProcessById(processId).Threads)
        EnumThreadWindows(thread.Id, 
            (hWnd, lParam) => { handles.Add(hWnd); return true; }, IntPtr.Zero);

    return handles;
}

Usage Example

The provided code demonstrates how to enumerate all windows associated with the Windows Explorer process:

private const uint WM_GETTEXT = 0x000D;

[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, 
    StringBuilder lParam);

[STAThread]
static void Main(string[] args)
{
    foreach (var handle in EnumerateProcessWindowHandles(
        Process.GetProcessesByName("explorer").First().Id))
    {
        StringBuilder message = new StringBuilder(1000);
        SendMessage(handle, WM_GETTEXT, message.Capacity, message);
        Console.WriteLine(message);
    }
}

By utilizing this solution, you can effectively enumerate all windows that belong to a specific process, providing valuable insights into the application's user interface.