Question

I need a functionality that enumerates through open explorer windows. And here is a code I’ve got:

delegate bool EnumThreadDelegate(IntPtr hWnd, IntPtr lParam);

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

static IEnumerable<IntPtr> EnumerateProcessWindowHandles(int processID)
{
    List<IntPtr> handles = new List<IntPtr>();

    foreach (ProcessThread thread in Process.GetProcessById(processID).Threads)
    {                                //what is the magic going on beneath this?? :o
        EnumThreadWindows(thread.Id, (hWnd, lParam) => { handles.Add(hWnd); return true;}, IntPtr.Zero);
    }
    return handles;
}

And the code continues here like this:

[DllImport("coredll.dll")]
static extern int ShowWindow(IntPtr hWnd, int nCmdShow);

const int SW_MINIMIZED = 6;

private void button1_Click(object sender, EventArgs e)
{
    foreach (IntPtr handle in EnumerateProcessWindowHandles(Process.GetProcessesByName("explorer")[0].Id))
    {
        ShowWindow(handle, SW_MINIMIZED);
    }
}

My question is, in the first block of code, how do I replace the lambda expression so that I can compile the code using C# 2.0 in VS 2005.

Answer 1

delegate bool EnumThreadDelegate(IntPtr hWnd, IntPtr lParam);

static IEnumerable<IntPtr> EnumerateProcessWindowHandles(int processID)
{
    List<IntPtr> handles = new List<IntPtr>();

    EnumThreadDelegate addWindowHandle = delegate(IntPtr hWnd, IntPtr param)
    {
        handles.Add(hWnd); 
        return true;
    };

    foreach (ProcessThread thread in Process.GetProcessById(processID).Threads)
    {
        EnumThreadWindows(thread.Id, addWindowHandle, IntPtr.Zero);
    }
    return handles;
}