document that CanRead() and GetImageCount() functions of wxImageHandlers do NOT modify the current stream position and that they require seekable streams; rename current GetImageCount() functions to DoGetImageCount() and put save-and-restore stream position logic in GetImageCount(); add comments in the various DoCanRead() and in DoGetImageCount() where the stream position is modified; remove unneeded SeekI(0) calls from DoCanRead() and DoGetImageCount() functions: they didn't allow to load images from non-seekable streams; implement forward-seeking in wxInputStream::SeekI() also for non-seekable streams

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60852 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/imaggif.h

@@ -35,8 +35,9 @@ public:
                           bool verbose = true, int index = -1);
     virtual bool SaveFile(wxImage *image, wxOutputStream& stream,
                           bool verbose=true);
-    virtual int GetImageCount(wxInputStream& stream);
+
 protected:
+    virtual int DoGetImageCount(wxInputStream& stream);
     virtual bool DoCanRead(wxInputStream& stream);
 #endif // wxUSE_STREAMS