Implement watching directory correctly in MSW wxFileSystemWatcher.

The directories used to be always monitored recursively, even when this wasn't
requested, in wxMSW implementation. Change this but also implement efficient
support for monitoring the entire hierarchies using the native support for
this.

Also update the sample to allow monitoring directories recursively as well.

See #12847.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67693 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/fswatcher.cpp

@@ -136,9 +136,32 @@ void wxFSWatcherImplMSW::SendEvent(wxFileSystemWatcherEvent& evt)
 
 bool wxFSWatcherImplMSW::DoSetUpWatch(wxFSWatchEntryMSW& watch)
 {
+    BOOL bWatchSubtree wxDUMMY_INITIALIZE(FALSE);
+
+    switch ( watch.GetType() )
+    {
+        case wxFSWPath_File:
+            wxLogError(_("Monitoring individual files for changes is not "
+                         "supported currently."));
+            return false;
+
+        case wxFSWPath_Dir:
+            bWatchSubtree = FALSE;
+            break;
+
+        case wxFSWPath_Tree:
+            bWatchSubtree = TRUE;
+            break;
+
+        case wxFSWPath_None:
+            wxFAIL_MSG( "Invalid watch type." );
+            return false;
+    }
+
     int flags = Watcher2NativeFlags(watch.GetFlags());
     int ret = ReadDirectoryChangesW(watch.GetHandle(), watch.GetBuffer(),
-                                    wxFSWatchEntryMSW::BUFFER_SIZE, FALSE,
+                                    wxFSWatchEntryMSW::BUFFER_SIZE,
+                                    bWatchSubtree,
                                     flags, NULL,
                                     watch.GetOverlapped(), NULL);
     if (!ret)
@@ -385,4 +408,30 @@ bool wxMSWFileSystemWatcher::Init()
     return ret;
 }
 
+bool
+wxMSWFileSystemWatcher::AddTree(const wxFileName& path,
+                                int events,
+                                const wxString& filter)
+{
+    if ( !filter.empty() )
+    {
+        // Use the inefficient generic version as we can only monitor
+        // everything under the given directory.
+        //
+        // Notice that it would probably be better to still monitor everything
+        // natively and filter out the changes we're not interested in.
+        return wxFileSystemWatcherBase::AddTree(path, events, filter);
+    }
+
+
+    if ( !path.DirExists() )
+    {
+        wxLogError(_("Can't monitor non-existent directory \"%s\" for changes."),
+                   path.GetFullPath());
+        return false;
+    }
+
+    return DoAdd(path, events, wxFSWPath_Tree);
+}
+
 #endif // wxUSE_FSWATCHER