@msdn=http://search.microsoft.com/search/results.aspx?qu=$$$ @pinvoke=http://pinvoke.net/$$$.htm Summary: The EnumWindows API !!!!C# Signature: [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam); !!!!VB.NET Signature: <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _ Private Shared Function EnumWindows( ByVal lpEnumFunc As EnumWindowsProc, _ ByVal lParam As IntPtr) As Boolean End Function !!!!User-Defined Types: EnumWindowsProc !!!!Notes: Callback EnumWindowsProc should return true to continue enumerating or false to stop. !!!!Tips & Tricks: The corresponding unmanaged return type is a 4-byte Win32 'BOOL', so mark the method with the MarshalAsAttribute(UnmanagedType.Bool). !!!Great sample using managed code and a delegate type for the call back from MSDN: http://msdn2.microsoft.com/en-us/library/d186xcf0(VS.71).aspx !!SAMPLE CODE!! using System.Runtime.InteropServices; public delegate bool CallBackPtr(int hwnd, int lParam); private CallBackPtr callBackPtr; public class EnumReport { [DllImport("user32.dll")] private static extern int EnumWindows(CallBackPtr callPtr, int lPar); public static bool Report(int hwnd, int lParam) { Console.WriteLine("Window handle is "+hwnd); return true; } } static void Main() { // note in other situations, it is important to keep // callBackPtr as a member variable so it doesnt GC while you're calling EnumWindows callBackPtr = new CallBackPtr(EnumReport.Report); EnumReport.EnumWindows(callBackPtr, 0); } !!Sample Code 2 (C#): public delegate bool EnumedWindow(IntPtr handleWindow, ArrayList handles); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool EnumWindows(EnumedWindow lpEnumFunc, ArrayList lParam); public static ArrayList GetWindows() { ArrayList windowHandles = new ArrayList(); EnumedWindow callBackPtr = GetWindowHandle; EnumWindows(callBackPtr, windowHandles); return windowHandles; } private static bool GetWindowHandle(IntPtr windowHandle, ArrayList windowHandles) { windowHandles.Add(windowHandle); return true; } !!Sample code demonstrating the passing of an object to the enum proc Oftentimes you'll want to have the EnumProc retrieve some data from a particular window and return it. You can do this by: * Defining a class to hold your custom data, and * Using a ref to that class in the EnumWindows() signature. using System.Runtime.InteropServices; using System.Text; public class WndSearcher { public static IntPtr SearchForWindow(string wndclass, string title) { SearchData sd = new SearchData { Wndclass=wndclass, Title=title }; EnumWindows(new EnumWindowsProc(EnumProc), ref sd); return sd.hWnd; } public static bool EnumProc(IntPtr hWnd, ref SearchData data) { // Check classname and title // This is different from FindWindow() in that the code below allows partial matches StringBuilder sb = new StringBuilder(1024); GetClassName(hWnd, sb, sb.Capacity); if (sb.ToString().StartsWith(data.Wndclass)) { sb = new StringBuilder(1024); GetWindowText(hWnd, sb, sb.Capacity); if (sb.ToString().StartsWith(data.Title)) { data.hWnd = hWnd; return false; // Found the wnd, halt enumeration } } return true; } public class SearchData { // You can put any dicks or Doms in here... public string Wndclass; public string Title; public IntPtr hWnd; } private delegate bool EnumWindowsProc(IntPtr hWnd, ref SearchData data); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, ref SearchData data); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount); } Then you'd call: // If you're viewing this page with IE, this *should* return the hwnd of the browser IntPtr hWnd = WndSearcher.SearchForWindow("IEFrame", "pinvoke.net: EnumWindows"); !!!!Alternative Managed API: The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a static method ManagedWinapi.Windows.SystemWindow.FilterToplevelWindows(). Documentation: EnumWindows@msdn on MSDN !!! Note: There are syntax errors in the above code! callBackPtr declared outside class EnumReport which is illegal ! Main() declared outside class EnumReport which is illegal ! After correction create an object of EnumReport class and call the functions using the object! Contact me at -- shrijit1991[at-the-rate-symbol]gmail.com If you feel that what I have written is wrong, feel free to remove it and drop a mail to me stating reasons for the same so that I can learn from my mistakes. - Thanks (Shrijit). The correct signature for EnumWindows in the example: [DllImport("user32.Dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, [MarshalAsAttribute(UnmanagedType.Struct)] ref SearchData data); (mirelvv) I never could get the compiler to accept this format. When called I'd get an error on the "ref SearchData" part. I worked around this by reverting the signature back to "int lParam", then using a member variable to hold the SearchData info. It's not pretty, but accomplishes the same thing. (acg)
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