Wpf and Hwnd unique name - wpf

Question

we have a wpf application that should be 'piloted' by a legacy win32 winform application. (We don't own the code ;) )
The legacy application should pilot our application (minimize, bring to front, shut, etc) via windowsclass name we should provide as a configuration parameter written into an ini file.
The problem is we cannot make it work with wpf since if we insert the classname Spy++ gives us, nothing happens. The point is Spi++ returns something like this
HwndWrapper[MyWpfProgram.exe;;16978ce2-3b8d-4c46-81ee-e1c6d6de4e6d]
where the guid is randomly generated at every run.
Is there any way to solve this issue?
Thank you.

Answer 1

There is no way to do what I asked. But we found a walkaround. "Simply" embedding the xaml windows within a windows form.
These are the steps we followed:
1 - Add a Windows Form to the project.
2 - Remove the app.xaml and make the new form the entry point of the application.
3 - Since we need the hwnd of the main.xaml we added this prop to its code behind
public IntPtr Hwnd
{
get { return new WindowInteropHelper(this).Handle; }
}
4 - then from the constructor of the form we create an instance of the wpf window class
private Main app;
public ContainerForm()
{
InitializeComponent();
app = new Main();
ElementHost.EnableModelessKeyboardInterop(app);
}
we needed
ElementHost.EnableModelessKeyboardInterop(app);
since we want all the keyboard input to pass from the the windows form to the xaml window
5 - now we want to bond the xpf window to the winform. In order to do that we need to use Windows Api and we do it at the OnShow event of the form (the reason why will be explicated later).
[DllImport("user32.dll", SetLastError = true)]
private static extern long SetFocus(IntPtr hWnd);
[DllImport("user32.dll", SetLastError = true)]
private static extern long SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
[DllImport("user32.dll", SetLastError = true)]
private static extern bool MoveWindow(IntPtr hwnd, int x, int y, int cx, int cy, bool repaint);
[DllImport("user32.dll", EntryPoint = "SetWindowLongA", SetLastError = true)]
private static extern long SetWindowLong(IntPtr hwnd, int nIndex, long dwNewLong);
private const int GWL_STYLE = (-16);
private const int WS_VISIBLE = 0x10000000;
private void ContainerForm_Shown(object sender, EventArgs e)
{
app.Show();
SetParent(app.Hwnd, this.Handle);
SetWindowLong(app.Hwnd, GWL_STYLE, WS_VISIBLE);
MoveWindow(app.Hwnd, 0, 0, this.Width, this.Height, true);
SetFocus(app.Hwnd);
}
with
SetParent(app.Hwnd, this.Handle);
wo do the magic, then with
SetWindowLong(app.Hwnd, GWL_STYLE, WS_VISIBLE);
we remove al the chrome from the wpf window (there is a border even if the window is defined borderless, don't ask me why)
then we make the wpf window fill all the client area of the winform
MoveWindow(app.Hwnd, 0, 0, this.Width, this.Height, true);
and then we focus the wpf window
SetFocus(app.Hwnd);
that's the reason why we do everything in the show event. Since if we do it at form's constructor, then the wpf window will loose its focus since the in winform the main window got the focus from the operating system.
We didn't understand why we needed to add the other api calls at this point, but if we left them at constructor's the trick didn't work.
Anyway,
problem solved ;)

Answer 2

Use HwndSource.
You can use native Windows API calls to create a window with the expected classname, then use HwndSource to add WPF content to it:
var source = HwndSource.FromHwnd(nativeWindowHandle);
source.RootVisual = mainGrid;
If you need to use a WPF window, I think you could still solve this with a "proxy" window, but it wouldn't be pretty:
Have your WPF application spawn a native message-only window.
Use HwndSource.AddHook to handle messages like WM_CLOSE, WM_SIZE on the native window and pass them along to the "real" WPF window.

Answer 3

For the window handles, titles, and class names, Spy++ uses fairly simple Windows APIs.
FindWindowEx http://msdn.microsoft.com/en-us/library/windows/desktop/ms633500%28v=vs.85%29.aspx
EnumWindows http://msdn.microsoft.com/en-us/library/windows/desktop/ms633497%28v=vs.85%29.aspx
GetClassName http://msdn.microsoft.com/en-us/library/windows/desktop/ms633582%28v=vs.85%29.aspx
You can create a "loader" program that will...
Start the wpf app
Use the above APIs to get the proper class names and windows handles
Edit the legacy INI
Start the legacy app