diff --git a/common/rfb/ZRLEEncoder.h b/common/rfb/ZRLEEncoder.h
new file mode 100644
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+++ b/common/rfb/ZRLEEncoder.h
@@ -0,0 +1,54 @@
+/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+#ifndef __RFB_ZRLEENCODER_H__
+#define __RFB_ZRLEENCODER_H__
+
+#include <rdr/MemOutStream.h>
+#include <rdr/ZlibOutStream.h>
+#include <rfb/Encoder.h>
+
+namespace rfb {
+
+  class ZRLEEncoder : public Encoder {
+  public:
+    static Encoder* create(SMsgWriter* writer);
+    virtual bool writeRect(const Rect& r, ImageGetter* ig, Rect* actual);
+    virtual ~ZRLEEncoder();
+
+    // setMaxLen() sets the maximum size in bytes of any ZRLE rectangle.  This
+    // can be used to stop the MemOutStream from growing too large.  The value
+    // must be large enough to allow for at least one row of ZRLE tiles.  So
+    // for example for a screen width of 2048 32-bit pixels this is 2K*4*64 =
+    // 512Kbytes plus a bit of overhead (the overhead is about 1/16 of the
+    // width, in this example about 128 bytes).
+    static void setMaxLen(int m) { maxLen = m; }
+
+    // setSharedMos() sets a MemOutStream to be shared amongst all
+    // ZRLEEncoders.  Should be called before any ZRLEEncoders are created.
+    static void setSharedMos(rdr::MemOutStream* mos_) { sharedMos = mos_; }
+
+  private:
+    ZRLEEncoder(SMsgWriter* writer);
+    SMsgWriter* writer;
+    rdr::ZlibOutStream zos;
+    rdr::MemOutStream* mos;
+    static rdr::MemOutStream* sharedMos;
+    static int maxLen;
+  };
+}
+#endif