How to enumerate running programs in .NETCF

I've been helping someone out in the MSDN Smart Device Forums lately with enumerating running programs. I thought I should share it since I don't much results from internet search engines on the topic. So here we go...

To enumerate top-level windows we use the EnumWindows method. To enumerate the running programs the same way the Task manager in Windows Mobile does, we just filter out what we don't need. What we don't want are windows that:

1. Have a parent window - We check by calling GetParent()
2. Is not visible - We check by calling IsWindowVisible()
3. Tool windows - We check by getting the current extended style (through GetWindowLong() of the window and checking if WS_EX_TOOLWINDOW is set

Here's a simple smart device console application the loads and displays a list of running programs:

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Runtime.InteropServices;

using System.Text;

namespace EnumWindowsNETCF

{

    class Program

    {

        static Dictionary<string, IntPtr> visibleWindows = new Dictionary<string, IntPtr>();

        static StringBuilder lpString;

        static bool visible;

        static bool hasOwner;

        static bool isToolWindow;

        delegate int WNDENUMPROC(IntPtr hwnd, uint lParam);

        const int GWL_EXSTYLE = -20;

        const uint WS_EX_TOOLWINDOW = 0x0080;

        [DllImport("coredll.dll")]

        static extern int EnumWindows(WNDENUMPROC lpEnumWindow, uint lParam);

        [DllImport("coredll.dll")]

        static extern bool IsWindowVisible(IntPtr hwnd);

        [DllImport("coredll.dll")]

        static extern IntPtr GetParent(IntPtr hwnd);

        [DllImport("coredll.dll")]

        static extern bool GetWindowText(IntPtr hwnd, StringBuilder lpString, int nMaxCount);

        [DllImport("coredll.dll")]

        static extern int GetWindowLong(IntPtr hwnd, int nIndex);

        static int Callback(IntPtr hwnd, uint lParam)

        {

            hasOwner = GetParent(hwnd) != IntPtr.Zero;

            visible = IsWindowVisible(hwnd);

            isToolWindow = (GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOOLWINDOW) != 0;

            lpString.Remove(0, lpString.Length);

            GetWindowText(hwnd, lpString, 1024);

            string key = lpString.ToString();

            if (!hasOwner &&

                visible &&

                !isToolWindow &&

                !string.IsNullOrEmpty(key) &&

                !visibleWindows.ContainsKey(key))

            {

                visibleWindows.Add(key, hwnd);

            }

            return 1;

        }

        static void Main()

        {

            lpString = new StringBuilder(1024);

            EnumWindows(Callback, 0);

            foreach (var key in visibleWindows.Keys)

            {

                IntPtr hwnd = visibleWindows[key];

                visible = IsWindowVisible(hwnd);

                lpString.Remove(0, lpString.Length);

                GetWindowText(hwnd, lpString, 1024);

                Debug.WriteLine("Handle: " + hwnd + "; Is Visible: " + visible + "; Text: " + lpString);

            }

        }

    }

}

I hope you find this useful, otherwise it can always be an addition to your utility library.

A long break...

Wow, I haven't noticed its been almost a year since I last wrote anything. Although I still try to take part in the community, I haven't written an article in ages. I think its time to get back into that habit and hope that I can help as much people as possible with their mobile development troubles.