diff --git a/x0vncserver/Image.h b/x0vncserver/Image.h
index 1a9ff1c..032e24a 100644
--- a/x0vncserver/Image.h
+++ b/x0vncserver/Image.h
@@ -1,4 +1,5 @@
 /* Copyright (C) 2002-2003 RealVNC Ltd.  All Rights Reserved.
+ * Copyright (C) 2004-2005 Constantin Kaplinsky.  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
@@ -23,26 +24,159 @@
 #define __IMAGE_H__
 
 #include <X11/Xlib.h>
-#include <X11/extensions/XShm.h>
+#include <X11/Xutil.h>
+
+//
+// Image class is an Xlib-based implementation of screen image storage.
+//
 
 class Image {
 
 public:
 
-  Image(Display* dpy, int width, int height);
-  ~Image();
+  Image(Display *d);
+  Image(Display *d, int width, int height);
+  virtual ~Image();
 
-  void get(Window w);
+  bool isTrueColor() { return trueColor; }
 
+  virtual void get(Window wnd, int x = 0, int y = 0);
+  virtual void get(Window wnd, int x, int y, int w, int h);
+
+  virtual void updateRect(Image *src, int dst_x = 0, int dst_y = 0);
+  virtual void updateRect(XImage *src, int dst_x = 0, int dst_y = 0);
+
+  // Pointer to corresponding XImage, made public for efficiency.
+  // NOTE: if this field is NULL, then no methods other than Init()
+  //       may be called.
   XImage* xim;
 
-private:
+protected:
 
-  bool createShmImage(int width, int height);
+  void Init(int width, int height);
 
-  Display* dpy;
-  XShmSegmentInfo* shminfo;
-  bool usingShm;
+  Display *dpy;
+  bool trueColor;
+
 };
 
-#endif
+//
+// ShmImage uses MIT-SHM extension of an X server to get image data.
+//
+
+#ifdef HAVE_MITSHM
+
+#include <X11/extensions/XShm.h>
+
+class ShmImage : public Image {
+
+public:
+
+  ShmImage(Display *d);
+  ShmImage(Display *d, int width, int height);
+  virtual ~ShmImage();
+
+  virtual void get(Window wnd, int x = 0, int y = 0);
+  virtual void get(Window wnd, int x, int y, int w, int h);
+
+protected:
+
+  void Init(int width, int height, const XVisualInfo *vinfo = NULL);
+
+  XShmSegmentInfo *shminfo;
+
+};
+
+//
+// IrixOverlayShmImage uses ReadDisplay extension of an X server to
+// get truecolor image data, regardless of the default X visual type. 
+// This method is available on Irix only.
+//
+
+#ifdef HAVE_READDISPLAY
+
+#include <X11/extensions/readdisplay.h>
+
+class IrixOverlayShmImage : public ShmImage {
+
+public:
+
+  IrixOverlayShmImage(Display *d);
+  IrixOverlayShmImage(Display *d, int width, int height);
+  virtual ~IrixOverlayShmImage();
+
+  virtual void get(Window wnd, int x = 0, int y = 0);
+  virtual void get(Window wnd, int x, int y, int w, int h);
+
+protected:
+
+  void Init(int width, int height);
+
+  // This method searches available X visuals for one that matches
+  // actual pixel format returned by XReadDisplay(). Returns true on
+  // success, false if there is no matching visual. On success, visual
+  // information is placed into the structure pointed by vinfo_ret.
+  bool getOverlayVisualInfo(XVisualInfo *vinfo_ret);
+
+  ShmReadDisplayBuf *readDisplayBuf;
+
+};
+
+#endif // HAVE_READDISPLAY
+#endif // HAVE_MITSHM
+
+//
+// SolarisOverlayImage uses SUN_OVL extension of an X server to get
+// truecolor image data, regardless of the default X visual type. This
+// method is available on Solaris only.
+//
+
+#ifdef HAVE_SUN_OVL
+
+#include <X11/extensions/transovl.h>
+
+class SolarisOverlayImage : public Image {
+
+public:
+
+  SolarisOverlayImage(Display *d);
+  SolarisOverlayImage(Display *d, int width, int height);
+  virtual ~SolarisOverlayImage();
+
+  virtual void get(Window wnd, int x = 0, int y = 0);
+  virtual void get(Window wnd, int x, int y, int w, int h);
+
+protected:
+
+  void Init(int width, int height);
+
+};
+
+#endif // HAVE_SUN_OVL
+
+//
+// ImageFactory class is used to produce instances of Image-derived
+// objects that are most appropriate for current X server and user
+// settings.
+//
+
+class ImageFactory {
+
+public:
+
+  ImageFactory(bool allowShm, bool allowOverlay);
+  virtual ~ImageFactory();
+
+  bool isShmAllowed()     { return mayUseShm; }
+  bool isOverlayAllowed() { return mayUseOverlay; }
+
+  virtual Image *newImage(Display *d, int width, int height);
+
+protected:
+
+  bool mayUseShm;
+  bool mayUseOverlay;
+
+};
+
+#endif // __IMAGE_H__