Document wxFS_XXXX flags for wxFileSystem::OpenFile.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43490 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -21,6 +21,8 @@ Changes in behaviour not resulting in compilation errors, please read this!
   instead of a char the range -128 - 127.
 - A sequence returned by wxFileSystem::FindFirst()/FindNext() may now be
   be scoped to a single instance of wxFileSystem.
+- Streams returned by wxFileSystem::OpenFile are not necessarily seekable by
+  default. Open with flags wxFS_READ | wxFS_SEEKABLE if seeking is required.
 
 
 Changes in behaviour which may result in compilation errors

docs/latex/wx/filesys.tex

@@ -153,7 +153,7 @@ Returns the next filename that matches parameters passed to \helpref{FindFirst}{
 
 \membersection{wxFileSystem::OpenFile}\label{wxfilesystemopenfile}
 
-\func{wxFSFile*}{OpenFile}{\param{const wxString\& }{location}}
+\func{wxFSFile*}{OpenFile}{\param{const wxString\& }{location}, \param{int }{flags = wxFS\_READ}}
 
 Opens the file and returns a pointer to a \helpref{wxFSFile}{wxfsfile} object
 or NULL if failed. It first tries to open the file in relative scope
@@ -161,6 +161,22 @@ or NULL if failed. It first tries to open the file in relative scope
 absolute path.  Note that the user is responsible for deleting the returned
 wxFSFile.  
 
+{\it flags} can be one or more of the following bit values ored together:
+
+\begin{verbatim}
+// Open Bit Flags
+enum {
+    wxFS_READ = 1,      // Open for reading
+    wxFS_SEEKABLE = 4   // Returned stream will be seekable
+};
+\end{verbatim}
+
+A stream opened with just the default {\it wxFS\_READ} flag may
+or may not be seekable depending on the underlying source.
+Passing {\it wxFS\_READ | wxFS\_SEEKABLE} for {\it flags} will
+back a stream that is not natively seekable with memory or a file
+and return a stream that is always seekable.
+
 
 \membersection{wxFileSystem::URLToFileName}\label{wxfilesystemurltofilename}