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

include/wx/fswatcher.h

@@ -55,6 +55,16 @@ enum
                          wxFSW_EVENT_WARNING | wxFSW_EVENT_ERROR
 };
 
+// Type of the path watched, used only internally for now.
+enum wxFSWPathType
+{
+    wxFSWPath_None,     // Invalid value for an initialized watch.
+    wxFSWPath_File,     // Plain file.
+    wxFSWPath_Dir,      // Watch a directory and the files in it.
+    wxFSWPath_Tree      // Watch a directory and all its children recursively.
+};
+
+
 /**
  * Event containing information about file system change.
  */
@@ -179,19 +189,17 @@ typedef void (wxEvtHandler::*wxFileSystemWatcherEventFunction)
 // wxFileSystemWatcherBase: interface for wxFileSystemWatcher
 // ----------------------------------------------------------------------------
 
-/**
- * Simple container to store information about one watched file
- */
+// Simple container to store information about one watched path.
 class wxFSWatchInfo
 {
 public:
     wxFSWatchInfo() :
-        m_path(wxEmptyString), m_events(-1)
+        m_events(-1), m_type(wxFSWPath_None)
     {
     }
 
-    wxFSWatchInfo(const wxString& path, int events) :
-        m_path(path), m_events(events)
+    wxFSWatchInfo(const wxString& path, int events, wxFSWPathType type) :
+        m_path(path), m_events(events), m_type(type)
     {
     }
 
@@ -205,9 +213,15 @@ public:
         return m_events;
     }
 
+    wxFSWPathType GetType() const
+    {
+        return m_type;
+    }
+
 protected:
     wxString m_path;
     int m_events;
+    wxFSWPathType m_type;
 };
 
 WX_DECLARE_STRING_HASH_MAP(wxFSWatchInfo, wxFSWatchInfoMap);
@@ -304,6 +318,11 @@ protected:
         return path_copy.GetFullPath();
     }
 
+    // Delegates the real work of adding the path to wxFSWatcherImpl::Add() and
+    // updates m_watches if the new path was successfully added.
+    bool DoAdd(const wxFileName& path, int events, wxFSWPathType type);
+
+
     wxFSWatchInfoMap m_watches;        // path=>wxFSWatchInfo map
     wxFSWatcherImpl* m_service;     // file system events service
     wxEvtHandler* m_owner;             // handler for file system events