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diff --git a/gs/base/gdevplnx.h b/gs/base/gdevplnx.h
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+/* Copyright (C) 2001-2006 Artifex Software, Inc.
+   All Rights Reserved.
+  
+   This software is provided AS-IS with no warranty, either express or
+   implied.
+
+   This software is distributed under license and may not be copied, modified
+   or distributed except as expressly authorized under the terms of that
+   license.  Refer to licensing information at http://www.artifex.com/
+   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
+   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
+*/
+
+/* $Id$*/
+/* Definitions and API for plane extraction device */
+/* Requires gxdevcli.h */
+
+#ifndef gdevplnx_INCLUDED
+#  define gdevplnx_INCLUDED
+
+#include "gxrplane.h"
+
+/*
+ * A plane-extraction device appears to its client to be a color-capable
+ * device, like its target; but it actually extracts a single color plane
+ * for rendering to yet another device, called the plane device (normally,
+ * but not necessarily, a memory device).  Clients must know the pixel
+ * representation in detail, since the plane is specified as a particular
+ * group of bits within the pixel.
+ *
+ * The original purpose of plane-extraction devices is for band list
+ * rendering for plane-oriented color printers.  Each per-plane rasterizing
+ * pass over the band list sends the output to a plane-extraction device for
+ * the plane being printed.  There is one special optimization to support
+ * this: on the theory that even bands containing output for multiple bands
+ * are likely to have many objects that only write white into that band, we
+ * remember whether any (non-white) marks have been made on the page so far,
+ * and if not, we simply skip any rendering operations that write white.
+ *
+ * The depth of the plane_extract device and its target are limited to 32
+ * bits; the depth of each plane is limited to 8 bits.  We could raise these
+ * without too much trouble if necessary, as long as each plane didn't
+ * exceed 32 bits.
+ */
+
+typedef struct gx_device_plane_extract_s {
+    gx_device_forward_common;
+	/* The following are set by the client before opening the device. */
+    gx_device *plane_dev;		/* the drawing device for the plane */
+    gx_render_plane_t plane;
+	/* The following are set by open_device. */
+    gx_color_index plane_white;
+    uint plane_mask;
+    bool plane_dev_is_memory;
+	/* The following change dynamically. */
+    bool any_marks;
+} gx_device_plane_extract;
+extern_st(st_device_plane_extract);
+#define public_st_device_plane_extract()	/* in gdevplnx.c */\
+  gs_public_st_complex_only(st_device_plane_extract, gx_device_plane_extract,\
+    "gx_device_plane_extract", 0, device_plane_extract_enum_ptrs,\
+    device_plane_extract_reloc_ptrs, gx_device_finalize)
+
+/* Initialize a plane extraction device. */
+int plane_device_init(gx_device_plane_extract *edev, gx_device *target,
+		      gx_device *plane_dev,
+		      const gx_render_plane_t *render_plane, bool clear);
+
+#endif /* gdevplnx_INCLUDED */