public HwndWrapper( int classStyle, int style, int exStyle, int x, int y, int width, int height, string name, IntPtr parent, HwndWrapperHook[] hooks) { _ownerThreadID = new SecurityCriticalDataForSet <int>(Thread.CurrentThread.ManagedThreadId); // First, add the set of hooks. This allows the hooks to receive the // messages sent to the window very early in the process. if (hooks != null) { for (int i = 0, iEnd = hooks.Length; i < iEnd; i++) { if (null != hooks[i]) { AddHook(hooks[i]); } } } _wndProc = new SecurityCriticalData <HwndWrapperHook>(new HwndWrapperHook(WndProc)); // We create the HwndSubclass object so that we can use its // window proc directly. We will not be "subclassing" the // window we create. HwndSubclass hwndSubclass = new HwndSubclass(_wndProc.Value); // Register a unique window class for this instance. NativeMethods.WNDCLASSEX_D wc_d = new NativeMethods.WNDCLASSEX_D(); IntPtr hNullBrush = UnsafeNativeMethods.CriticalGetStockObject(NativeMethods.NULL_BRUSH); if (hNullBrush == IntPtr.Zero) { throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error()); } IntPtr hInstance = UnsafeNativeMethods.GetModuleHandle(null); // We need to keep the Delegate object alive through the call to CreateWindowEx(). // Subclass.WndProc will install a better delegate (to the same function) when it // processes the first message. // But this first delegate needs be held alive until then. NativeMethods.WndProc initialWndProc = new NativeMethods.WndProc(hwndSubclass.SubclassWndProc); // The class name is a concat of AppName, ThreadName, and RandomNumber. // Register will fail if the string gets over 255 in length. // So limit each part to a reasonable amount. string appName; if (null != AppDomain.CurrentDomain.FriendlyName && 128 <= AppDomain.CurrentDomain.FriendlyName.Length) { appName = AppDomain.CurrentDomain.FriendlyName.Substring(0, 128); } else { appName = AppDomain.CurrentDomain.FriendlyName; } string threadName; if (null != Thread.CurrentThread.Name && 64 <= Thread.CurrentThread.Name.Length) { threadName = Thread.CurrentThread.Name.Substring(0, 64); } else { threadName = Thread.CurrentThread.Name; } // Create a suitable unique class name. _classAtom = 0; string randomName = Guid.NewGuid().ToString(); string className = String.Format(CultureInfo.InvariantCulture, "HwndWrapper[{0};{1};{2}]", appName, threadName, randomName); wc_d.cbSize = Marshal.SizeOf(typeof(NativeMethods.WNDCLASSEX_D)); wc_d.style = classStyle; wc_d.lpfnWndProc = initialWndProc; wc_d.cbClsExtra = 0; wc_d.cbWndExtra = 0; wc_d.hInstance = hInstance; wc_d.hIcon = IntPtr.Zero; wc_d.hCursor = IntPtr.Zero; wc_d.hbrBackground = hNullBrush; wc_d.lpszMenuName = ""; wc_d.lpszClassName = className; wc_d.hIconSm = IntPtr.Zero; // Register the unique class for this instance. // Note we use a GUID in the name so we are confident that // the class name should be unique. And RegisterClassEx won't // fail (for that reason). _classAtom = UnsafeNativeMethods.RegisterClassEx(wc_d); // call CreateWindow _isInCreateWindow = true; try { _handle = new SecurityCriticalDataClass <IntPtr>(UnsafeNativeMethods.CreateWindowEx(exStyle, className, name, style, x, y, width, height, new HandleRef(null, parent), new HandleRef(null, IntPtr.Zero), new HandleRef(null, IntPtr.Zero), null)); } finally { _isInCreateWindow = false; if (_handle == null || _handle.Value == IntPtr.Zero) { // Because the HwndSubclass is pinned, but the HWND creation failed, // we need to manually clean it up. hwndSubclass.Dispose(); } } GC.KeepAlive(initialWndProc); }