Imported nx-X11-3.1.0-1.tar.gznx-X11/3.1.0-1

Summary: Imported nx-X11-3.1.0-1.tar.gz
Keywords:

Imported nx-X11-3.1.0-1.tar.gz
into Git repository

1 files changed, 3905 insertions, 0 deletions

diff --git a/nx-X11/programs/Xserver/mi/mibstore.c b/nx-X11/programs/Xserver/mi/mibstore.c
new file mode 100644
index 000000000..98947217c
--- /dev/null
+++ b/nx-X11/programs/Xserver/mi/mibstore.c
@@ -0,0 +1,3905 @@
+/* $Xorg: mibstore.c,v 1.4 2001/02/09 02:05:20 xorgcvs Exp $ */
+/***********************************************************
+
+Copyright 1987, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+
+Copyright 1987 by the Regents of the University of California
+
+                        All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose and without fee is hereby granted, provided
+that the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation, and that the name The Open Group not be used in advertising or publicity
+pertaining to distribution of the software without specific, written prior
+permission.  
+
+The University of California makes no representations about the suitability
+of this software for any purpose.  It is provided "as is" without express or
+implied warranty.
+
+******************************************************************/
+
+/* $XFree86: xc/programs/Xserver/mi/mibstore.c,v 1.10tsi Exp $ */
+
+#define NEED_EVENTS
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#include <X11/X.h>
+#include <X11/Xmd.h>
+#include <X11/Xproto.h>
+#include "misc.h"
+#include "regionstr.h"
+#include "scrnintstr.h"
+#include "gcstruct.h"
+#include "windowstr.h"
+#include "pixmapstr.h"
+#include <X11/fonts/fontstruct.h>
+#include "dixfontstr.h"
+#include "dixstruct.h"		/* For requestingClient */
+#include "mi.h"
+#include "mibstorest.h"
+
+/*
+ * When the server fails to allocate a backing store pixmap, if you want
+ * it to dynamically retry to allocate backing store on every subsequent
+ * graphics op, you can enable BSEAGER; otherwise, backing store will be
+ * disabled on the window until it is unmapped and then remapped.
+ */
+/* #define BSEAGER */
+
+/*-
+ * NOTES ON USAGE:
+ *
+ * The functions in this file implement a machine-independent backing-store
+ * scheme. To use it, the output library must do the following:
+ *	- Provide a SaveAreas function that takes a destination pixmap, a
+ *	    region of the areas to save (in the pixmap's coordinate system)
+ *	    and the screen origin of the region. It should copy the areas from
+ *	    the screen into the pixmap.
+ *	- Provide a RestoreAreas function that takes a source pixmap, a region
+ *	    of the areas to restore (in the screen's coordinate system) and the
+ *	    origin of the pixmap on the screen. It should copy the areas from
+ *	    the pixmap into the screen.
+ *	- Provide a SetClipmaskRgn function that takes a gc and a region
+ *	    and merges the region into any CT_PIXMAP client clip that
+ *	    is specified in the GC.  This routine is only needed if
+ *	    miValidateBackingStore will see CT_PIXMAP clip lists; not
+ *	    true for any of the sample servers (which convert the PIXMAP
+ *	    clip lists into CT_REGION clip lists; an expensive but simple
+ *	    to code option).
+ *	- The function placed in a window's ClearToBackground vector must call
+ *	    pScreen->ClearBackingStore with the window, followed by
+ *	    the window-relative x and y coordinates, followed by the width and
+ *	    height of the area to be cleared, followed by the generateExposures
+ *	    flag. This has been taken care of in miClearToBackground.
+ *	- Whatever determines GraphicsExpose events for the CopyArea and
+ *	    CopyPlane requests should call pWin->backStorage->ExposeCopy
+ *	    with the source and destination drawables, the GC used, a source-
+ *	    window-relative region of exposed areas, the source and destination
+ *	    coordinates and the bitplane copied, if CopyPlane, or 0, if
+ *	    CopyArea.
+ *
+ * JUSTIFICATION
+ *    This is a cross between saving everything and just saving the
+ * obscued areas (as in Pike's layers.)  This method has the advantage
+ * of only doing each output operation once per pixel, visible or
+ * invisible, and avoids having to do all the crufty storage
+ * management of keeping several separate rectangles.  Since the
+ * ddx layer ouput primitives are required to draw through clipping
+ * rectangles anyway, sending multiple drawing requests for each of
+ * several rectangles isn't necessary.  (Of course, it could be argued
+ * that the ddx routines should just take one rectangle each and
+ * get called multiple times, but that would make taking advantage of
+ * smart hardware harder, and probably be slower as well.)
+ */
+
+#define SETUP_BACKING_TERSE(pGC) \
+    miBSGCPtr	pGCPrivate = (miBSGCPtr)(pGC)->devPrivates[miBSGCIndex].ptr; \
+    GCFuncs	*oldFuncs = pGC->funcs;
+
+#define SETUP_BACKING(pDrawable,pGC) \
+    miBSWindowPtr pBackingStore = \
+    	(miBSWindowPtr)((WindowPtr)(pDrawable))->backStorage; \
+    DrawablePtr	  pBackingDrawable = (DrawablePtr) \
+        pBackingStore->pBackingPixmap; \
+    SETUP_BACKING_TERSE(pGC) \
+    GCPtr	pBackingGC = pGCPrivate->pBackingGC;
+
+#define PROLOGUE(pGC) { \
+    pGC->ops = pGCPrivate->wrapOps;\
+    pGC->funcs = pGCPrivate->wrapFuncs; \
+    }
+
+#define EPILOGUE(pGC) { \
+    pGCPrivate->wrapOps = (pGC)->ops; \
+    (pGC)->ops = &miBSGCOps; \
+    (pGC)->funcs = oldFuncs; \
+    }
+   
+static void	    miCreateBSPixmap(WindowPtr pWin, BoxPtr pExtents);
+static void	    miDestroyBSPixmap(WindowPtr pWin);
+static void	    miTileVirtualBS(WindowPtr pWin);
+static void	    miBSAllocate(WindowPtr pWin), miBSFree(WindowPtr pWin);
+static Bool	    miBSCreateGCPrivate(GCPtr pGC);
+static void	    miBSClearBackingRegion(WindowPtr pWin, RegionPtr pRgn);
+
+#define MoreCopy0 ;
+#define MoreCopy2 *dstCopy++ = *srcCopy++; *dstCopy++ = *srcCopy++;
+#define MoreCopy4 MoreCopy2 MoreCopy2
+
+#define copyData(src,dst,n,morecopy) \
+{ \
+    register short *srcCopy = (short *)(src); \
+    register short *dstCopy = (short *)(dst); \
+    register int i; \
+    register int bsx = pBackingStore->x; \
+    register int bsy = pBackingStore->y; \
+    for (i = n; --i >= 0; ) \
+    { \
+	*dstCopy++ = *srcCopy++ - bsx; \
+	*dstCopy++ = *srcCopy++ - bsy; \
+	morecopy \
+    } \
+}
+
+#define copyPoints(src,dst,n,mode) \
+if (mode == CoordModeOrigin) \
+{ \
+    copyData(src,dst,n,MoreCopy0); \
+} \
+else \
+{ \
+    memmove((char *)(dst), (char *)(src), (n) << 2); \
+    *((short *)(dst)) -= pBackingStore->x; \
+    *((short *)(dst) + 1) -= pBackingStore->y; \
+}
+
+/*
+ * wrappers for screen funcs
+ */
+
+static int  miBSScreenIndex;
+static unsigned long miBSGeneration = 0;
+
+static Bool	    miBSCloseScreen(int i, ScreenPtr pScreen);
+static void	    miBSGetImage(DrawablePtr pDrawable, int sx, int sy,
+				 int w, int h, unsigned int format,
+				 unsigned long planemask, char *pdstLine);
+static void	    miBSGetSpans(DrawablePtr pDrawable, int wMax,
+				 DDXPointPtr ppt, int *pwidth, int nspans,
+				 char *pdstStart);
+static Bool	    miBSChangeWindowAttributes(WindowPtr pWin,
+					       unsigned long mask);
+static Bool	    miBSCreateGC(GCPtr pGC);
+static Bool	    miBSDestroyWindow(WindowPtr pWin);
+
+/*
+ * backing store screen functions
+ */
+
+static void	    miBSSaveDoomedAreas(WindowPtr pWin, RegionPtr pObscured,
+					int dx, int dy);
+static RegionPtr    miBSRestoreAreas(WindowPtr pWin, RegionPtr prgnExposed);
+static void	    miBSExposeCopy(WindowPtr pSrc, DrawablePtr pDst,
+				   GCPtr pGC, RegionPtr prgnExposed,
+				   int srcx, int srcy, int dstx, int dsty,
+				   unsigned long plane);
+static RegionPtr    miBSTranslateBackingStore(WindowPtr pWin, int windx,
+					      int windy, RegionPtr oldClip,
+					      int oldx, int oldy);
+static RegionPtr    miBSClearBackingStore(WindowPtr pWin, int x, int y,
+					  int w, int h, Bool generateExposures);
+static void	    miBSDrawGuarantee(WindowPtr pWin, GCPtr pGC,
+				      int guarantee);
+
+/*
+ * wrapper vectors for GC funcs and ops
+ */
+
+static int  miBSGCIndex;
+
+static void miBSValidateGC(GCPtr pGC, unsigned long stateChanges,
+			   DrawablePtr pDrawable);
+static void miBSCopyGC(GCPtr pGCSrc, unsigned long mask, GCPtr pGCDst);
+static void miBSDestroyGC(GCPtr pGC);
+static void miBSChangeGC(GCPtr pGC, unsigned long mask);
+static void miBSChangeClip(GCPtr pGC, int type, pointer pvalue, int nrects);
+static void miBSDestroyClip(GCPtr pGC);
+static void miBSCopyClip(GCPtr pgcDst, GCPtr pgcSrc);
+
+static GCFuncs	miBSGCFuncs = {
+    miBSValidateGC,
+    miBSChangeGC,
+    miBSCopyGC,
+    miBSDestroyGC,
+    miBSChangeClip,
+    miBSDestroyClip,
+    miBSCopyClip,
+};
+
+static void	    miBSFillSpans(DrawablePtr pDrawable, GCPtr pGC, int nInit,
+				  DDXPointPtr pptInit, int *pwidthInit,
+				  int fSorted);
+static void	    miBSSetSpans(DrawablePtr pDrawable, GCPtr pGC, char *psrc,
+				 DDXPointPtr ppt, int *pwidth, int nspans,
+				 int fSorted);
+static void	    miBSPutImage(DrawablePtr pDrawable, GCPtr pGC, int depth,
+				 int x, int y, int w, int h, int leftPad,
+				 int format, char *pBits);
+static RegionPtr    miBSCopyArea(DrawablePtr pSrc, DrawablePtr pDst,
+				 GCPtr pGC, int srcx, int srcy, int w, int h,
+				 int dstx, int dsty);
+static RegionPtr    miBSCopyPlane(DrawablePtr pSrc, DrawablePtr pDst,
+				  GCPtr pGC, int srcx, int srcy, int w, int h,
+				  int dstx, int dsty, unsigned long plane);
+static void	    miBSPolyPoint(DrawablePtr pDrawable, GCPtr pGC, int mode,
+				  int npt, xPoint *pptInit);
+static void	    miBSPolylines(DrawablePtr pDrawable, GCPtr pGC, int mode,
+				  int npt, DDXPointPtr pptInit);
+static void	    miBSPolySegment(DrawablePtr pDrawable, GCPtr pGC, int nseg,
+				    xSegment *pSegs);
+static void	    miBSPolyRectangle(DrawablePtr pDrawable, GCPtr pGC,
+				      int nrects, xRectangle *pRects);
+static void	    miBSPolyArc(DrawablePtr pDrawable, GCPtr pGC, int narcs,
+				xArc *parcs);
+static void	    miBSFillPolygon(DrawablePtr pDrawable, GCPtr pGC,
+				    int shape, int mode, int count,
+				    DDXPointPtr pPts);
+static void	    miBSPolyFillRect(DrawablePtr pDrawable, GCPtr pGC,
+				     int nrectFill, xRectangle *prectInit);
+static void	    miBSPolyFillArc(DrawablePtr pDrawable, GCPtr pGC,
+				    int narcs, xArc *parcs);
+static int	    miBSPolyText8(DrawablePtr pDrawable, GCPtr pGC,
+				  int x, int y, int count, char *chars);
+static int	    miBSPolyText16(DrawablePtr pDrawable, GCPtr pGC,
+				   int x, int y, int count,
+				   unsigned short *chars);
+static void	    miBSImageText8(DrawablePtr pDrawable, GCPtr pGC,
+				   int x, int y, int count, char *chars);
+static void	    miBSImageText16(DrawablePtr pDrawable, GCPtr pGC,
+				    int x, int y, int count,
+				    unsigned short *chars);
+static void	    miBSImageGlyphBlt(DrawablePtr pDrawable, GCPtr pGC,
+				      int x, int y, unsigned int nglyph,
+				      CharInfoPtr *ppci, pointer pglyphBase);
+static void	    miBSPolyGlyphBlt(DrawablePtr pDrawable, GCPtr pGC,
+				     int x, int y, unsigned int nglyph,
+				     CharInfoPtr *ppci, pointer pglyphBase);
+static void	    miBSPushPixels(GCPtr pGC, PixmapPtr pBitMap,
+				   DrawablePtr pDst, int w, int h,
+				   int x, int y);
+#ifdef NEED_LINEHELPER
+static void	    miBSLineHelper(void);
+#endif
+
+static GCOps miBSGCOps = {
+    miBSFillSpans,	miBSSetSpans,	    miBSPutImage,	
+    miBSCopyArea,	miBSCopyPlane,	    miBSPolyPoint,
+    miBSPolylines,	miBSPolySegment,    miBSPolyRectangle,
+    miBSPolyArc,	miBSFillPolygon,    miBSPolyFillRect,
+    miBSPolyFillArc,	miBSPolyText8,	    miBSPolyText16,
+    miBSImageText8,	miBSImageText16,    miBSImageGlyphBlt,
+    miBSPolyGlyphBlt,	miBSPushPixels
+#ifdef NEED_LINEHELPER
+    , miBSLineHelper
+#endif
+};
+
+#define FUNC_PROLOGUE(pGC, pPriv) \
+    ((pGC)->funcs = pPriv->wrapFuncs),\
+    ((pGC)->ops = pPriv->wrapOps)
+
+#define FUNC_EPILOGUE(pGC, pPriv) \
+    ((pGC)->funcs = &miBSGCFuncs),\
+    ((pGC)->ops = &miBSGCOps)
+
+/*
+ * every GC in the server is initially wrapped with these
+ * "cheap" functions.  This allocates no memory and is used
+ * to discover GCs used with windows which have backing
+ * store enabled
+ */
+
+static void miBSCheapValidateGC(GCPtr pGC, unsigned long stateChanges,
+				DrawablePtr pDrawable);
+static void miBSCheapCopyGC(GCPtr pGCSrc, unsigned long mask, GCPtr pGCDst);
+static void miBSCheapDestroyGC(GCPtr pGC);
+static void miBSCheapChangeGC(GCPtr pGC, unsigned long mask);
+static void miBSCheapChangeClip(GCPtr pGC, int type, pointer pvalue,
+				int nrects);
+static void miBSCheapDestroyClip(GCPtr pGC);
+static void miBSCheapCopyClip(GCPtr pgcDst, GCPtr pgcSrc);
+
+static GCFuncs miBSCheapGCFuncs = {
+    miBSCheapValidateGC,
+    miBSCheapChangeGC,
+    miBSCheapCopyGC,
+    miBSCheapDestroyGC,
+    miBSCheapChangeClip,
+    miBSCheapDestroyClip,
+    miBSCheapCopyClip,
+};
+
+#define CHEAP_FUNC_PROLOGUE(pGC) \
+    ((pGC)->funcs = (GCFuncs *) (pGC)->devPrivates[miBSGCIndex].ptr)
+
+#define CHEAP_FUNC_EPILOGUE(pGC) \
+    ((pGC)->funcs = &miBSCheapGCFuncs)
+
+/*
+ * called from device screen initialization proc.  Gets a GCPrivateIndex
+ * and wraps appropriate per-screen functions.  pScreen->BackingStoreFuncs
+ * must be previously initialized.
+ */
+
+void
+miInitializeBackingStore (pScreen)
+    ScreenPtr	pScreen;
+{
+    miBSScreenPtr    pScreenPriv;
+
+    if (miBSGeneration != serverGeneration)
+    {
+	miBSScreenIndex = AllocateScreenPrivateIndex ();
+	if (miBSScreenIndex < 0)
+	    return;
+	miBSGCIndex = AllocateGCPrivateIndex ();
+	miBSGeneration = serverGeneration;
+    }
+    if (!AllocateGCPrivate(pScreen, miBSGCIndex, 0))
+	return;
+    pScreenPriv = (miBSScreenPtr) xalloc (sizeof (miBSScreenRec));
+    if (!pScreenPriv)
+	return;
+
+    pScreenPriv->CloseScreen = pScreen->CloseScreen;
+    pScreenPriv->GetImage = pScreen->GetImage;
+    pScreenPriv->GetSpans = pScreen->GetSpans;
+    pScreenPriv->ChangeWindowAttributes = pScreen->ChangeWindowAttributes;
+    pScreenPriv->CreateGC = pScreen->CreateGC;
+    pScreenPriv->DestroyWindow = pScreen->DestroyWindow;
+
+    pScreen->CloseScreen = miBSCloseScreen;
+    pScreen->GetImage = miBSGetImage;
+    pScreen->GetSpans = miBSGetSpans;
+    pScreen->ChangeWindowAttributes = miBSChangeWindowAttributes;
+    pScreen->CreateGC = miBSCreateGC;
+    pScreen->DestroyWindow = miBSDestroyWindow;
+
+    pScreen->SaveDoomedAreas = miBSSaveDoomedAreas;
+    pScreen->RestoreAreas = miBSRestoreAreas;
+    pScreen->ExposeCopy = miBSExposeCopy;
+    pScreen->TranslateBackingStore = miBSTranslateBackingStore;
+    pScreen->ClearBackingStore = miBSClearBackingStore;
+    pScreen->DrawGuarantee = miBSDrawGuarantee;
+
+    pScreen->devPrivates[miBSScreenIndex].ptr = (pointer) pScreenPriv;
+}
+
+/*
+ * Screen function wrappers
+ */
+
+#define SCREEN_PROLOGUE(pScreen, field)\
+  ((pScreen)->field = \
+   ((miBSScreenPtr) \
+    (pScreen)->devPrivates[miBSScreenIndex].ptr)->field)
+
+#define SCREEN_EPILOGUE(pScreen, field, wrapper)\
+    ((pScreen)->field = wrapper)
+
+/*
+ * CloseScreen wrapper -- unwrap everything, free the private data
+ * and call the wrapped function
+ */
+
+static Bool
+miBSCloseScreen (i, pScreen)
+    int		i;
+    ScreenPtr	pScreen;
+{
+    miBSScreenPtr   pScreenPriv;
+
+    pScreenPriv = (miBSScreenPtr) pScreen->devPrivates[miBSScreenIndex].ptr;
+
+    pScreen->CloseScreen = pScreenPriv->CloseScreen;
+    pScreen->GetImage = pScreenPriv->GetImage;
+    pScreen->GetSpans = pScreenPriv->GetSpans;
+    pScreen->ChangeWindowAttributes = pScreenPriv->ChangeWindowAttributes;
+    pScreen->CreateGC = pScreenPriv->CreateGC;
+
+    xfree ((pointer) pScreenPriv);
+
+    return (*pScreen->CloseScreen) (i, pScreen);
+}
+
+static void miBSFillVirtualBits(DrawablePtr pDrawable, GCPtr pGC,
+				RegionPtr pRgn, int x, int y, int state,
+				PixUnion pixunion, unsigned long planemask);
+
+static void
+miBSGetImage (pDrawable, sx, sy, w, h, format, planemask, pdstLine)
+    DrawablePtr	    pDrawable;
+    int		    sx, sy, w, h;
+    unsigned int    format;
+    unsigned long   planemask;
+    char	    *pdstLine;
+{
+    ScreenPtr		    pScreen = pDrawable->pScreen;
+    BoxRec		    bounds;
+    unsigned char	    depth;
+    
+    SCREEN_PROLOGUE (pScreen, GetImage);
+
+    if (pDrawable->type != DRAWABLE_PIXMAP &&
+	((WindowPtr) pDrawable)->visibility != VisibilityUnobscured)
+    {
+	PixmapPtr	pPixmap;
+	miBSWindowPtr	pWindowPriv;
+	GCPtr		pGC = NULL;
+	WindowPtr	pWin, pSrcWin;
+	int		xoff, yoff;
+	RegionRec	Remaining;
+	RegionRec	Border;
+	RegionRec	Inside;
+	BoxPtr		pBox;
+	int		n;
+
+	pWin = (WindowPtr) pDrawable;
+	pPixmap = 0;
+	depth = pDrawable->depth;
+	bounds.x1 = sx + pDrawable->x;
+	bounds.y1 = sy + pDrawable->y;
+	bounds.x2 = bounds.x1 + w;
+	bounds.y2 = bounds.y1 + h;
+	REGION_INIT(pScreen, &Remaining, &bounds, 0);
+	for (;;)
+ 	{
+	    bounds.x1 = sx + pDrawable->x - pWin->drawable.x;
+	    bounds.y1 = sy + pDrawable->y - pWin->drawable.y;
+	    bounds.x2 = bounds.x1 + w;
+	    bounds.y2 = bounds.y1 + h;
+	    if (pWin->viewable && pWin->backStorage &&
+		pWin->drawable.depth == depth &&
+	        (RECT_IN_REGION(pScreen, &(pWindowPriv =
+		    (miBSWindowPtr) pWin->backStorage)->SavedRegion,
+		    &bounds) != rgnOUT ||
+		 RECT_IN_REGION(pScreen, &Remaining,
+		  REGION_EXTENTS(pScreen, &pWin->borderSize)) != rgnOUT))
+	    {
+		if (!pPixmap)
+		{
+		    XID	subWindowMode = IncludeInferiors;
+		    int	x, y;
+
+		    pPixmap = (*pScreen->CreatePixmap) (pScreen, w, h, depth);
+		    if (!pPixmap)
+			goto punt;
+		    pGC = GetScratchGC (depth, pScreen);
+		    if (!pGC)
+		    {
+			(*pScreen->DestroyPixmap) (pPixmap);
+			goto punt;
+		    }
+		    ChangeGC (pGC, GCSubwindowMode, &subWindowMode);
+		    ValidateGC ((DrawablePtr)pPixmap, pGC);
+		    REGION_NULL(pScreen, &Border);
+		    REGION_NULL(pScreen, &Inside);
+		    pSrcWin = (WindowPtr) pDrawable;
+		    x = sx;
+		    y = sy;
+		    if (pSrcWin->parent)
+		    {
+			x += pSrcWin->origin.x;
+			y += pSrcWin->origin.y;
+			pSrcWin = pSrcWin->parent;
+		    }
+		    (*pGC->ops->CopyArea) ((DrawablePtr)pSrcWin,
+ 					    (DrawablePtr)pPixmap, pGC,
+					    x, y, w, h,
+					    0, 0);
+		    REGION_SUBTRACT(pScreen, &Remaining, &Remaining,
+				    &((WindowPtr) pDrawable)->borderClip);
+		}
+
+		REGION_INTERSECT(pScreen, &Inside, &Remaining, &pWin->winSize);
+		REGION_TRANSLATE(pScreen, &Inside,
+					     -pWin->drawable.x,
+ 					     -pWin->drawable.y);
+		REGION_INTERSECT(pScreen, &Inside, &Inside,
+				 &pWindowPriv->SavedRegion);
+
+		/* offset of sub-window in GetImage pixmap */
+		xoff = pWin->drawable.x - pDrawable->x - sx;
+		yoff = pWin->drawable.y - pDrawable->y - sy;
+
+		if (REGION_NUM_RECTS(&Inside) > 0)
+		{
+		    switch (pWindowPriv->status)
+		    {
+		    case StatusContents:
+			pBox = REGION_RECTS(&Inside);
+			for (n = REGION_NUM_RECTS(&Inside); --n >= 0;)
+			{
+			    (*pGC->ops->CopyArea) (
+				(DrawablePtr)pWindowPriv->pBackingPixmap,
+						   (DrawablePtr)pPixmap, pGC,
+						   pBox->x1 - pWindowPriv->x,
+						   pBox->y1 - pWindowPriv->y,
+						   pBox->x2 - pBox->x1,
+						   pBox->y2 - pBox->y1,
+						   pBox->x1 + xoff,
+						   pBox->y1 + yoff);
+			    ++pBox;
+			}
+			break;
+		    case StatusVirtual:
+		    case StatusVDirty:
+			if (pWindowPriv->backgroundState == BackgroundPixmap ||
+			    pWindowPriv->backgroundState == BackgroundPixel)
+			miBSFillVirtualBits ((DrawablePtr) pPixmap, pGC, &Inside,
+					    xoff, yoff,
+					    (int) pWindowPriv->backgroundState,
+					    pWindowPriv->background, ~0L);
+			break;
+		    }
+		}
+		REGION_SUBTRACT(pScreen, &Border, &pWin->borderSize,
+				&pWin->winSize);
+		REGION_INTERSECT(pScreen, &Border, &Border, &Remaining);
+		if (REGION_NUM_RECTS(&Border) > 0)
+		{
+		    REGION_TRANSLATE(pScreen, &Border, -pWin->drawable.x,
+						  -pWin->drawable.y);
+		    miBSFillVirtualBits ((DrawablePtr) pPixmap, pGC, &Border,
+				    	xoff, yoff,
+				    	pWin->borderIsPixel ? (int)BackgroundPixel : (int)BackgroundPixmap,
+				    	pWin->border, ~0L);
+		}
+	    }
+
+	    if (pWin->viewable && pWin->firstChild)
+		pWin = pWin->firstChild;
+	    else
+	    {
+		while (!pWin->nextSib && pWin != (WindowPtr) pDrawable)
+		    pWin = pWin->parent;
+		if (pWin == (WindowPtr) pDrawable)
+		    break;
+		pWin = pWin->nextSib;
+	    }
+	}
+
+	REGION_UNINIT(pScreen, &Remaining);
+
+	if (pPixmap)
+	{
+	    REGION_UNINIT(pScreen, &Border);
+	    REGION_UNINIT(pScreen, &Inside);
+	    (*pScreen->GetImage) ((DrawablePtr) pPixmap,
+		0, 0, w, h, format, planemask, pdstLine);
+	    (*pScreen->DestroyPixmap) (pPixmap);
+	    FreeScratchGC (pGC);
+	}
+	else
+	{
+	    goto punt;
+	}
+    }
+    else
+    {
+punt:	;
+	(*pScreen->GetImage) (pDrawable, sx, sy, w, h,
+			      format, planemask, pdstLine);
+    }
+
+    SCREEN_EPILOGUE (pScreen, GetImage, miBSGetImage);
+}
+
+static void
+miBSGetSpans (pDrawable, wMax, ppt, pwidth, nspans, pdstStart)
+    DrawablePtr	pDrawable;
+    int		wMax;
+    DDXPointPtr	ppt;
+    int		*pwidth;
+    int		nspans;
+    char	*pdstStart;
+{
+    ScreenPtr		    pScreen = pDrawable->pScreen;
+    BoxRec		    bounds;
+    int			    i;
+    WindowPtr		    pWin;
+    int			    dx, dy;
+    
+    SCREEN_PROLOGUE (pScreen, GetSpans);
+
+    if (pDrawable->type != DRAWABLE_PIXMAP && ((WindowPtr) pDrawable)->backStorage)
+    {
+	PixmapPtr	pPixmap;
+	miBSWindowPtr	pWindowPriv;
+	GCPtr		pGC;
+
+	pWin = (WindowPtr) pDrawable;
+	pWindowPriv = (miBSWindowPtr) pWin->backStorage;
+	pPixmap = pWindowPriv->pBackingPixmap;
+
+    	bounds.x1 = ppt->x;
+    	bounds.y1 = ppt->y;
+    	bounds.x2 = bounds.x1 + *pwidth;
+    	bounds.y2 = ppt->y;
+    	for (i = 0; i < nspans; i++)
+    	{
+	    if (ppt[i].x < bounds.x1)
+	    	bounds.x1 = ppt[i].x;
+	    if (ppt[i].x + pwidth[i] > bounds.x2)
+	    	bounds.x2 = ppt[i].x + pwidth[i];
+	    if (ppt[i].y < bounds.y1)
+	    	bounds.y1 = ppt[i].y;
+	    else if (ppt[i].y > bounds.y2)
+	    	bounds.y2 = ppt[i].y;
+    	}
+    
+    	switch (RECT_IN_REGION(pScreen, &pWindowPriv->SavedRegion, &bounds))
+ 	{
+	case rgnPART:
+	    if (!pPixmap)
+	    {
+		miCreateBSPixmap (pWin, NullBox);
+		if (!(pPixmap = pWindowPriv->pBackingPixmap))
+		    break;
+	    }
+	    pWindowPriv->status = StatusNoPixmap;
+	    pGC = GetScratchGC(pPixmap->drawable.depth,
+			       pPixmap->drawable.pScreen);
+	    if (pGC)
+	    {
+		ValidateGC ((DrawablePtr) pPixmap, pGC);
+		(*pGC->ops->CopyArea)
+		    (pDrawable, (DrawablePtr) pPixmap, pGC,
+		    bounds.x1, bounds.y1,
+		    bounds.x2 - bounds.x1, bounds.y2 - bounds.y1,
+		    bounds.x1 + pPixmap->drawable.x - pWin->drawable.x -
+		     pWindowPriv->x,
+		    bounds.y1 + pPixmap->drawable.y - pWin->drawable.y -
+		     pWindowPriv->y);
+		FreeScratchGC(pGC);
+	    }
+	    pWindowPriv->status = StatusContents;
+	    /* fall through */
+	case rgnIN:
+	    if (!pPixmap)
+	    {
+		miCreateBSPixmap (pWin, NullBox);
+		if (!(pPixmap = pWindowPriv->pBackingPixmap))
+		    break;
+	    }
+	    dx = pPixmap->drawable.x - pWin->drawable.x - pWindowPriv->x;
+	    dy = pPixmap->drawable.y - pWin->drawable.y - pWindowPriv->y;
+	    for (i = 0; i < nspans; i++)
+	    {
+		ppt[i].x += dx;
+		ppt[i].y += dy;
+	    }
+	    (*pScreen->GetSpans) ((DrawablePtr) pPixmap, wMax, ppt, pwidth,
+				  nspans, pdstStart);
+	    break;
+	case rgnOUT:
+	    (*pScreen->GetSpans) (pDrawable, wMax, ppt, pwidth, nspans,
+				  pdstStart);
+	    break;
+	}
+    }
+    else
+    {
+	(*pScreen->GetSpans) (pDrawable, wMax, ppt, pwidth, nspans, pdstStart);
+    }
+
+    SCREEN_EPILOGUE (pScreen, GetSpans, miBSGetSpans);
+}
+
+static Bool
+miBSChangeWindowAttributes (pWin, mask)
+    WindowPtr	    pWin;
+    unsigned long   mask;
+{
+    ScreenPtr	pScreen;
+    Bool	ret;
+
+    pScreen = pWin->drawable.pScreen;
+
+    SCREEN_PROLOGUE (pScreen, ChangeWindowAttributes);
+
+    ret = (*pScreen->ChangeWindowAttributes) (pWin, mask);
+
+    if (ret && (mask & CWBackingStore))
+    {
+	if (pWin->backingStore != NotUseful || pWin->DIXsaveUnder)
+	    miBSAllocate (pWin);
+	else
+	    miBSFree (pWin);
+    }
+
+    SCREEN_EPILOGUE (pScreen, ChangeWindowAttributes, miBSChangeWindowAttributes);
+
+    return ret;
+}
+
+/*
+ * GC Create wrapper.  Set up the cheap GC func wrappers to track
+ * GC validation on BackingStore windows
+ */
+
+static Bool
+miBSCreateGC (pGC)
+    GCPtr   pGC;
+{
+    ScreenPtr	pScreen = pGC->pScreen;
+    Bool	ret;
+
+    SCREEN_PROLOGUE (pScreen, CreateGC);
+    
+    if ( (ret = (*pScreen->CreateGC) (pGC)) )
+    {
+    	pGC->devPrivates[miBSGCIndex].ptr = (pointer) pGC->funcs;
+    	pGC->funcs = &miBSCheapGCFuncs;
+    }
+
+    SCREEN_EPILOGUE (pScreen, CreateGC, miBSCreateGC);
+
+    return ret;
+}
+
+static Bool
+miBSDestroyWindow (pWin)
+    WindowPtr	pWin;
+{
+    ScreenPtr	pScreen = pWin->drawable.pScreen;
+    Bool	ret;
+
+    SCREEN_PROLOGUE (pScreen, DestroyWindow);
+    
+    ret = (*pScreen->DestroyWindow) (pWin);
+
+    miBSFree (pWin);
+
+    SCREEN_EPILOGUE (pScreen, DestroyWindow, miBSDestroyWindow);
+
+    return ret;
+}
+
+/*
+ * cheap GC func wrappers.  Simply track validation on windows
+ * with backing store to enable the real func/op wrappers
+ */
+
+static void
+miBSCheapValidateGC (pGC, stateChanges, pDrawable)
+    GCPtr	    pGC;
+    unsigned long   stateChanges;
+    DrawablePtr	    pDrawable;
+{
+    CHEAP_FUNC_PROLOGUE (pGC);
+    
+    if (pDrawable->type != DRAWABLE_PIXMAP &&
+        ((WindowPtr) pDrawable)->backStorage != NULL &&
+	miBSCreateGCPrivate (pGC))
+    {
+	(*pGC->funcs->ValidateGC) (pGC, stateChanges, pDrawable);
+    }
+    else
+    {
+	(*pGC->funcs->ValidateGC) (pGC, stateChanges, pDrawable);
+
+	/* rewrap funcs as Validate may have changed them */
+	pGC->devPrivates[miBSGCIndex].ptr = (pointer) pGC->funcs;
+
+	CHEAP_FUNC_EPILOGUE (pGC);
+    }
+}
+
+static void
+miBSCheapChangeGC (pGC, mask)
+    GCPtr   pGC;
+    unsigned long   mask;
+{
+    CHEAP_FUNC_PROLOGUE (pGC);
+
+    (*pGC->funcs->ChangeGC) (pGC, mask);
+
+    CHEAP_FUNC_EPILOGUE (pGC);
+}
+
+static void
+miBSCheapCopyGC (pGCSrc, mask, pGCDst)
+    GCPtr   pGCSrc, pGCDst;
+    unsigned long   mask;
+{
+    CHEAP_FUNC_PROLOGUE (pGCDst);
+
+    (*pGCDst->funcs->CopyGC) (pGCSrc, mask, pGCDst);
+
+    CHEAP_FUNC_EPILOGUE (pGCDst);
+}
+
+static void
+miBSCheapDestroyGC (pGC)
+    GCPtr   pGC;
+{
+    CHEAP_FUNC_PROLOGUE (pGC);
+
+    (*pGC->funcs->DestroyGC) (pGC);
+
+    /* leave it unwrapped */
+}
+
+static void
+miBSCheapChangeClip (pGC, type, pvalue, nrects)
+    GCPtr   pGC;
+    int		type;
+    pointer	pvalue;
+    int		nrects;
+{
+    CHEAP_FUNC_PROLOGUE (pGC);
+
+    (*pGC->funcs->ChangeClip) (pGC, type, pvalue, nrects);
+
+    CHEAP_FUNC_EPILOGUE (pGC);
+}
+
+static void
+miBSCheapCopyClip(pgcDst, pgcSrc)
+    GCPtr pgcDst, pgcSrc;
+{
+    CHEAP_FUNC_PROLOGUE (pgcDst);
+
+    (* pgcDst->funcs->CopyClip)(pgcDst, pgcSrc);
+
+    CHEAP_FUNC_EPILOGUE (pgcDst);
+}
+
+static void
+miBSCheapDestroyClip(pGC)
+    GCPtr	pGC;
+{
+    CHEAP_FUNC_PROLOGUE (pGC);
+
+    (* pGC->funcs->DestroyClip)(pGC);
+
+    CHEAP_FUNC_EPILOGUE (pGC);
+}
+
+/*
+ * create the full func/op wrappers for a GC
+ */
+
+static Bool
+miBSCreateGCPrivate (pGC)
+    GCPtr   pGC;
+{
+    miBSGCRec	*pPriv;
+
+    pPriv = (miBSGCRec *) xalloc (sizeof (miBSGCRec));
+    if (!pPriv)
+	return FALSE;
+    pPriv->pBackingGC = NULL;
+    pPriv->guarantee = GuaranteeNothing;
+    pPriv->serialNumber = 0;
+    pPriv->stateChanges = (1 << (GCLastBit + 1)) - 1;
+    pPriv->wrapOps = pGC->ops;
+    pPriv->wrapFuncs = pGC->funcs;
+    pGC->funcs = &miBSGCFuncs;
+    pGC->ops = &miBSGCOps;
+    pGC->devPrivates[miBSGCIndex].ptr = (pointer) pPriv;
+    return TRUE;
+}
+
+static void
+miBSDestroyGCPrivate (GCPtr pGC)
+{
+    miBSGCRec	*pPriv;
+
+    pPriv = (miBSGCRec *) pGC->devPrivates[miBSGCIndex].ptr;
+    if (pPriv)
+    {
+	pGC->devPrivates[miBSGCIndex].ptr = (pointer) pPriv->wrapFuncs;
+	pGC->funcs = &miBSCheapGCFuncs;
+	pGC->ops = pPriv->wrapOps;
+	if (pPriv->pBackingGC)
+	    FreeGC (pPriv->pBackingGC, (GContext) 0);
+	xfree ((pointer) pPriv);
+    }
+}
+
+/*
+ * GC ops -- wrap each GC operation with our own function
+ */
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSFillSpans --
+ *	Perform a FillSpans, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSFillSpans(pDrawable, pGC, nInit, pptInit, pwidthInit, fSorted)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		nInit;			/* number of spans to fill */
+    DDXPointPtr pptInit;		/* pointer to list of start points */
+    int		*pwidthInit;		/* pointer to list of n widths */
+    int 	fSorted;
+{
+    DDXPointPtr	pptCopy, pptReset;
+    int 	*pwidthCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pptCopy = (DDXPointPtr)ALLOCATE_LOCAL(nInit*sizeof(DDXPointRec));
+    pwidthCopy=(int *)ALLOCATE_LOCAL(nInit*sizeof(int));
+    if (pptCopy && pwidthCopy)
+    {
+	copyData(pptInit, pptCopy, nInit, MoreCopy0);
+	memmove((char *)pwidthCopy,(char *)pwidthInit,nInit*sizeof(int));
+
+	(* pGC->ops->FillSpans)(pDrawable, pGC, nInit, pptInit,
+			     pwidthInit, fSorted);
+	if (pGC->miTranslate)
+	{
+	    int	dx, dy;
+	    int	nReset;
+
+	    pptReset = pptCopy;
+	    dx = pDrawable->x - pBackingDrawable->x;
+	    dy = pDrawable->y - pBackingDrawable->y;
+	    nReset = nInit;
+	    while (nReset--)
+	    {
+		pptReset->x -= dx;
+		pptReset->y -= dy;
+		++pptReset;
+	    }
+	}
+	(* pBackingGC->ops->FillSpans)(pBackingDrawable,
+				  pBackingGC, nInit, pptCopy, pwidthCopy,
+				  fSorted);
+    }
+    if (pwidthCopy) DEALLOCATE_LOCAL(pwidthCopy);
+    if (pptCopy) DEALLOCATE_LOCAL(pptCopy);
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSSetSpans --
+ *	Perform a SetSpans, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSSetSpans(pDrawable, pGC, psrc, ppt, pwidth, nspans, fSorted)
+    DrawablePtr		pDrawable;
+    GCPtr		pGC;
+    char		*psrc;
+    register DDXPointPtr ppt;
+    int			*pwidth;
+    int			nspans;
+    int			fSorted;
+{
+    DDXPointPtr	pptCopy, pptReset;
+    int 	*pwidthCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pptCopy = (DDXPointPtr)ALLOCATE_LOCAL(nspans*sizeof(DDXPointRec));
+    pwidthCopy=(int *)ALLOCATE_LOCAL(nspans*sizeof(int));
+    if (pptCopy && pwidthCopy)
+    {
+	copyData(ppt, pptCopy, nspans, MoreCopy0);
+	memmove((char *)pwidthCopy,(char *)pwidth,nspans*sizeof(int));
+
+	(* pGC->ops->SetSpans)(pDrawable, pGC, psrc, ppt, pwidth,
+			       nspans, fSorted);
+	if (pGC->miTranslate)
+	{
+	    int	dx, dy;
+	    int	nReset;
+
+	    pptReset = pptCopy;
+	    dx = pDrawable->x - pBackingDrawable->x;
+	    dy = pDrawable->y - pBackingDrawable->y;
+	    nReset = nspans;
+	    while (nReset--)
+	    {
+		pptReset->x -= dx;
+		pptReset->y -= dy;
+		++pptReset;
+	    }
+	}
+	(* pBackingGC->ops->SetSpans)(pBackingDrawable, pBackingGC,
+				psrc, pptCopy, pwidthCopy, nspans, fSorted);
+    }
+    if (pwidthCopy) DEALLOCATE_LOCAL(pwidthCopy);
+    if (pptCopy) DEALLOCATE_LOCAL(pptCopy);
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPutImage --
+ *	Perform a PutImage, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPutImage(pDrawable, pGC, depth, x, y, w, h, leftPad, format, pBits)
+    DrawablePtr	  pDrawable;
+    GCPtr   	  pGC;
+    int		  depth;
+    int	    	  x;
+    int	    	  y;
+    int	    	  w;
+    int	    	  h;
+    int		  leftPad;
+    int	    	  format;
+    char    	  *pBits;
+{
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    (*pGC->ops->PutImage)(pDrawable, pGC,
+		     depth, x, y, w, h, leftPad, format, pBits);
+    (*pBackingGC->ops->PutImage)(pBackingDrawable, pBackingGC,
+		     depth, x - pBackingStore->x, y - pBackingStore->y,
+		     w, h, leftPad, format, pBits);
+
+    EPILOGUE (pGC);
+}
+
+typedef RegionPtr (* CopyAreaProcPtr)(DrawablePtr, DrawablePtr, GCPtr,
+				      int, int, int, int, int, int);
+typedef RegionPtr (* CopyPlaneProcPtr)(DrawablePtr, DrawablePtr, GCPtr,
+				      int, int, int, int, int, int,
+				      unsigned long bitPlane);
+/*-
+ *-----------------------------------------------------------------------
+ * miBSDoCopy --
+ *	Perform a CopyArea or CopyPlane within a window that has backing
+ *	store enabled.
+ *
+ * Results:
+ *	TRUE if the copy was performed or FALSE if a regular one should
+ *	be done.
+ *
+ * Side Effects:
+ *	Things are copied (no s***!)
+ *
+ * Notes:
+ *	The idea here is to form two regions that cover the source box.
+ *	One contains the exposed rectangles while the other contains
+ *	the obscured ones. An array of <box, drawable> pairs is then
+ *	formed where the <box> indicates the area to be copied and the
+ *	<drawable> indicates from where it is to be copied (exposed regions
+ *	come from the screen while obscured ones come from the backing
+ *	pixmap). The array 'sequence' is then filled with the indices of
+ *	the pairs in the order in which they should be copied to prevent
+ *	things from getting screwed up. A call is also made through the
+ *	backingGC to take care of any copying into the backing pixmap.
+ *
+ *-----------------------------------------------------------------------
+ */
+static Bool
+miBSDoCopy(
+    WindowPtr	  pWin,	    	    /* Window being scrolled */
+    GCPtr   	  pGC,	    	    /* GC we're called through */
+    int	    	  srcx,	    	    /* X of source rectangle */
+    int	    	  srcy,	    	    /* Y of source rectangle */
+    int	    	  w,	    	    /* Width of source rectangle */
+    int	    	  h,	    	    /* Height of source rectangle */
+    int	    	  dstx,	    	    /* X of destination rectangle */
+    int	    	  dsty,	    	    /* Y of destination rectangle */
+    unsigned long plane,    	    /* Plane to copy (0 for CopyArea) */
+    CopyPlaneProcPtr copyProc,      /* Procedure to call to perform the copy */
+    RegionPtr	  *ppRgn)	    /* resultant Graphics Expose region */
+{
+    RegionPtr 	    	pRgnExp;    /* Exposed region */
+    RegionPtr	  	pRgnObs;    /* Obscured region */
+    BoxRec	  	box;	    /* Source box (screen coord) */
+    struct BoxDraw {
+	BoxPtr	  	pBox;	    	/* Source box */
+	enum {
+	    win, pix
+	}   	  	source;	    	/* Place from which to copy */
+    }	    	  	*boxes;	    /* Array of box/drawable pairs covering
+				     * source box. */
+    int  	  	*sequence;  /* Sequence of boxes to move */
+    register int  	i, j, k, l, y;
+    register BoxPtr	pBox;
+    int	    	  	dx, dy, nrects;
+    Bool    	  	graphicsExposures;
+    CopyPlaneProcPtr  	pixCopyProc;
+    int			numRectsExp, numRectsObs;
+    BoxPtr		pBoxExp, pBoxObs;
+
+    SETUP_BACKING (pWin, pGC);
+    (void)oldFuncs;
+
+    /*
+     * Create a region of exposed boxes in pRgnExp.
+     */
+    box.x1 = srcx + pWin->drawable.x;
+    box.x2 = box.x1 + w;
+    box.y1 = srcy + pWin->drawable.y;
+    box.y2 = box.y1 + h;
+    
+    pRgnExp = REGION_CREATE(pGC->pScreen, &box, 1);
+    REGION_INTERSECT(pGC->pScreen, pRgnExp, pRgnExp, &pWin->clipList);
+    pRgnObs = REGION_CREATE(pGC->pScreen, NULL, 1);
+    REGION_INVERSE( pGC->pScreen, pRgnObs, pRgnExp, &box);
+
+    /*
+     * Translate regions into window coordinates for proper calls
+     * to the copyProc, then make sure none of the obscured region sticks
+     * into invalid areas of the backing pixmap.
+     */
+    REGION_TRANSLATE(pGC->pScreen, pRgnExp,
+				      -pWin->drawable.x,
+				      -pWin->drawable.y);
+    REGION_TRANSLATE(pGC->pScreen, pRgnObs,
+				      -pWin->drawable.x,
+				      -pWin->drawable.y);
+    REGION_INTERSECT(pGC->pScreen, pRgnObs, pRgnObs, &pBackingStore->SavedRegion);
+
+    /*
+     * If the obscured region is empty, there's no point being fancy.
+     */
+    if (!REGION_NOTEMPTY(pGC->pScreen, pRgnObs))
+    {
+	REGION_DESTROY(pGC->pScreen, pRgnExp);
+	REGION_DESTROY(pGC->pScreen, pRgnObs);
+
+	return (FALSE);
+    }
+
+    numRectsExp = REGION_NUM_RECTS(pRgnExp);
+    pBoxExp = REGION_RECTS(pRgnExp);
+    pBoxObs = REGION_RECTS(pRgnObs);
+    numRectsObs = REGION_NUM_RECTS(pRgnObs);
+    nrects = numRectsExp + numRectsObs;
+    
+    boxes = (struct BoxDraw *)ALLOCATE_LOCAL(nrects * sizeof(struct BoxDraw));
+    sequence = (int *) ALLOCATE_LOCAL(nrects * sizeof(int));
+    *ppRgn = NULL;
+
+    if (!boxes || !sequence)
+    {
+	if (sequence) DEALLOCATE_LOCAL(sequence);
+	if (boxes) DEALLOCATE_LOCAL(boxes);
+	REGION_DESTROY(pGC->pScreen, pRgnExp);
+	REGION_DESTROY(pGC->pScreen, pRgnObs);
+
+	return(TRUE);
+    }
+
+    /*
+     * Order the boxes in the two regions so we know from which drawable
+     * to copy which box, storing the result in the boxes array
+     */
+    for (i = 0, j = 0, k = 0;
+	 (i < numRectsExp) && (j < numRectsObs);
+	 k++)
+    {
+	if (pBoxExp[i].y1 < pBoxObs[j].y1)
+	{
+	    boxes[k].pBox = &pBoxExp[i];
+	    boxes[k].source = win;
+	    i++;
+	}
+	else if ((pBoxObs[j].y1 < pBoxExp[i].y1) ||
+		 (pBoxObs[j].x1 < pBoxExp[i].x1))
+	{
+	    boxes[k].pBox = &pBoxObs[j];
+	    boxes[k].source = pix;
+	    j++;
+	}
+	else
+	{
+	    boxes[k].pBox = &pBoxExp[i];
+	    boxes[k].source = win;
+	    i++;
+	}
+    }
+
+    /*
+     * Catch any leftover boxes from either region (note that only
+     * one can have leftover boxes...)
+     */
+    if (i != numRectsExp)
+    {
+	do
+	{
+	    boxes[k].pBox = &pBoxExp[i];
+	    boxes[k].source = win;
+	    i++;
+	    k++;
+	} while (i < numRectsExp);
+
+    }
+    else
+    {
+	do
+	{
+	    boxes[k].pBox = &pBoxObs[j];
+	    boxes[k].source = pix;
+	    j++;
+	    k++;
+	} while (j < numRectsObs);
+    }
+    
+    if (dsty <= srcy)
+    {
+	/*
+	 * Scroll up or vertically stationary, so vertical order is ok.
+	 */
+	if (dstx <= srcx)
+	{
+	    /*
+	     * Scroll left or horizontally stationary, so horizontal order
+	     * is ok as well.
+	     */
+	    for (i = 0; i < nrects; i++)
+	    {
+		sequence[i] = i;
+	    }
+	}
+	else
+	{
+	    /*
+	     * Scroll right. Need to reverse the rectangles within each
+	     * band.
+	     */
+	    for (i = 0, j = 1, k = 0;
+		 i < nrects;
+		 j = i + 1, k = i)
+	    {
+		y = boxes[i].pBox->y1;
+		while ((j < nrects) && (boxes[j].pBox->y1 == y))
+		{
+		    j++;
+		}
+		for (j--; j >= k; j--, i++)
+		{
+		    sequence[i] = j;
+		}
+	    }
+	}
+    }
+    else
+    {
+	/*
+	 * Scroll down. Must reverse vertical banding, at least.
+	 */
+	if (dstx < srcx)
+	{
+	    /*
+	     * Scroll left. Horizontal order is ok.
+	     */
+	    for (i = nrects - 1, j = i - 1, k = i, l = 0;
+		 i >= 0;
+		 j = i - 1, k = i)
+	    {
+		/*
+		 * Find extent of current horizontal band, then reverse
+		 * the order of the whole band.
+		 */
+		y = boxes[i].pBox->y1;
+		while ((j >= 0) && (boxes[j].pBox->y1 == y))
+		{
+		    j--;
+		}
+		for (j++; j <= k; j++, i--, l++)
+		{
+		    sequence[l] = j;
+		}
+	    }
+	}
+	else
+	{
+	    /*
+	     * Scroll right or horizontal stationary.
+	     * Reverse horizontal order as well (if stationary, horizontal
+	     * order can be swapped without penalty and this is faster
+             * to compute).
+	     */
+	    for (i = 0, j = nrects - 1; i < nrects; i++, j--)
+	    {
+		sequence[i] = j;
+	    }
+	}
+    }
+	    
+    /*
+     * XXX: To avoid getting multiple NoExpose events from this operation,
+     * we turn OFF graphicsExposures in the gc and deal with any uncopied
+     * areas later, if there's something not in backing-store.
+     */
+
+    graphicsExposures = pGC->graphicsExposures;
+    pGC->graphicsExposures = FALSE;
+    
+    dx = dstx - srcx;
+    dy = dsty - srcy;
+
+    /*
+     * Figure out which copy procedure to use from the backing GC. Note we
+     * must do this because some implementations (sun's, e.g.) have
+     * pBackingGC a fake GC with the real one below it, thus the devPriv for
+     * pBackingGC won't be what the output library expects.
+     */
+    if (plane != 0)
+    {
+	pixCopyProc = pBackingGC->ops->CopyPlane;
+    }
+    else
+    {
+	pixCopyProc = (CopyPlaneProcPtr)pBackingGC->ops->CopyArea;
+    }
+    
+    for (i = 0; i < nrects; i++)
+    {
+	pBox = boxes[sequence[i]].pBox;
+	
+	/*
+	 * If we're copying from the pixmap, we need to place its contents
+	 * onto the screen before scrolling the pixmap itself. If we're copying
+	 * from the window, we need to copy its contents into the pixmap before
+	 * we scroll the window itself.
+	 */
+	if (boxes[sequence[i]].source == pix)
+	{
+	    (void) (* copyProc) (pBackingDrawable, &(pWin->drawable), pGC,
+			  pBox->x1 - pBackingStore->x,
+			  pBox->y1 - pBackingStore->y,
+			  pBox->x2 - pBox->x1, pBox->y2 - pBox->y1,
+			  pBox->x1 + dx, pBox->y1 + dy, plane);
+	    (void) (* pixCopyProc) (pBackingDrawable, pBackingDrawable, pBackingGC,
+			     pBox->x1 - pBackingStore->x,
+			     pBox->y1 - pBackingStore->y,
+			     pBox->x2 - pBox->x1, pBox->y2 - pBox->y1,
+			     pBox->x1 + dx - pBackingStore->x,
+			     pBox->y1 + dy - pBackingStore->y, plane);
+	}
+	else
+	{
+	    (void) (* pixCopyProc) (&(pWin->drawable), pBackingDrawable, pBackingGC,
+			     pBox->x1, pBox->y1,
+			     pBox->x2 - pBox->x1, pBox->y2 - pBox->y1,
+			     pBox->x1 + dx - pBackingStore->x,
+			     pBox->y1 + dy - pBackingStore->y, plane);
+	    (void) (* copyProc) (&(pWin->drawable), &(pWin->drawable), pGC,
+			  pBox->x1, pBox->y1,
+			  pBox->x2 - pBox->x1, pBox->y2 - pBox->y1,
+			  pBox->x1 + dx, pBox->y1 + dy, plane);
+	}
+    }
+    DEALLOCATE_LOCAL(sequence);
+    DEALLOCATE_LOCAL(boxes);
+
+    pGC->graphicsExposures = graphicsExposures;
+    /*
+     * Form union of rgnExp and rgnObs and see if covers entire area
+     * to be copied.  Store the resultant region for miBSCopyArea
+     * to return to dispatch which will send the appropriate expose
+     * events.
+     */
+    REGION_UNION(pGC->pScreen, pRgnExp, pRgnExp, pRgnObs);
+    box.x1 = srcx;
+    box.x2 = srcx + w;
+    box.y1 = srcy;
+    box.y2 = srcy + h;
+    if (RECT_IN_REGION(pGC->pScreen, pRgnExp, &box) == rgnIN)
+    {
+	REGION_EMPTY(pGC->pScreen, pRgnExp);
+    }
+    else
+    {
+	REGION_INVERSE( pGC->pScreen, pRgnExp, pRgnExp, &box);
+	REGION_TRANSLATE( pGC->pScreen, pRgnExp,
+					   dx + pWin->drawable.x,
+ 					   dy + pWin->drawable.y);
+	REGION_INTERSECT( pGC->pScreen, pRgnObs, pRgnExp, &pWin->clipList);
+	(*pWin->drawable.pScreen->PaintWindowBackground) (pWin,
+						pRgnObs, PW_BACKGROUND);
+	REGION_TRANSLATE( pGC->pScreen, pRgnExp,
+					   -pWin->drawable.x,
+ 					   -pWin->drawable.y);
+	miBSClearBackingRegion (pWin, pRgnExp);
+    }
+    if (graphicsExposures)
+	*ppRgn = pRgnExp;
+    else
+	REGION_DESTROY(pGC->pScreen, pRgnExp);
+    REGION_DESTROY(pGC->pScreen, pRgnObs);
+
+    return (TRUE);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSCopyArea --
+ *	Perform a CopyArea from the source to the destination, extracting
+ *	from the source's backing-store and storing into the destination's
+ *	backing-store without messing anything up. If the source and
+ *	destination are different, there's not too much to worry about:
+ *	we can just issue several calls to the regular CopyArea function.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static RegionPtr
+miBSCopyArea (pSrc, pDst, pGC, srcx, srcy, w, h, dstx, dsty)
+    DrawablePtr	  pSrc;
+    DrawablePtr	  pDst;
+    GCPtr   	  pGC;
+    int	    	  srcx;
+    int	    	  srcy;
+    int	    	  w;
+    int	    	  h;
+    int	    	  dstx;
+    int	    	  dsty;
+{
+    BoxPtr	pExtents;
+    long	dx, dy;
+    int		bsrcx, bsrcy, bw, bh, bdstx, bdsty;
+    RegionPtr	pixExposed = 0, winExposed = 0;
+
+    SETUP_BACKING(pDst, pGC);
+
+    PROLOGUE(pGC);
+
+    if ((pSrc != pDst) ||
+	(!miBSDoCopy((WindowPtr)pSrc, pGC, srcx, srcy, w, h, dstx, dsty,
+		     (unsigned long) 0, (CopyPlaneProcPtr)pGC->ops->CopyArea,
+		     &winExposed)))
+    {
+	/*
+	 * always copy to the backing store first, miBSDoCopy
+	 * returns FALSE if the *source* region is disjoint
+	 * from the backing store saved region.  So, copying
+	 * *to* the backing store is always safe
+	 */
+	if (pGC->clientClipType != CT_PIXMAP)
+	{
+	    /*
+	     * adjust srcx, srcy, w, h, dstx, dsty to be clipped to
+	     * the backing store.  An unnecessary optimisation,
+	     * but a useful one when GetSpans is slow.
+	     */
+	    pExtents = REGION_EXTENTS(pDst->pScreen,
+				      (RegionPtr)pBackingGC->clientClip);
+	    bsrcx = srcx;
+	    bsrcy = srcy;
+	    bw = w;
+	    bh = h;
+	    bdstx = dstx;
+	    bdsty = dsty;
+	    dx = pExtents->x1 - bdstx;
+	    if (dx > 0)
+	    {
+		bsrcx += dx;
+		bdstx += dx;
+		bw -= dx;
+	    }
+	    dy = pExtents->y1 - bdsty;
+	    if (dy > 0)
+	    {
+		bsrcy += dy;
+		bdsty += dy;
+		bh -= dy;
+	    }
+	    dx = (bdstx + bw) - pExtents->x2;
+	    if (dx > 0)
+		bw -= dx;
+	    dy = (bdsty + bh) - pExtents->y2;
+	    if (dy > 0)
+		bh -= dy;
+	    if (bw > 0 && bh > 0)
+		pixExposed = (* pBackingGC->ops->CopyArea) (pSrc, 
+			    pBackingDrawable, pBackingGC, 
+			    bsrcx, bsrcy, bw, bh, bdstx - pBackingStore->x,
+			    bdsty - pBackingStore->y);
+	}
+	else
+	    pixExposed = (* pBackingGC->ops->CopyArea) (pSrc, 
+			    pBackingDrawable, pBackingGC,
+			    srcx, srcy, w, h,
+			    dstx - pBackingStore->x, dsty - pBackingStore->y);
+
+	winExposed = (* pGC->ops->CopyArea) (pSrc, pDst, pGC, srcx, srcy, w, h, dstx, dsty);
+    }
+
+    /*
+     * compute the composite graphics exposure region
+     */
+    if (winExposed)
+    {
+	if (pixExposed){
+	    REGION_UNION(pDst->pScreen, winExposed, winExposed, pixExposed);
+	    REGION_DESTROY(pDst->pScreen, pixExposed);
+	}
+    } else
+	winExposed = pixExposed;
+
+    EPILOGUE (pGC);
+
+    return winExposed;
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSCopyPlane --
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static RegionPtr
+miBSCopyPlane (pSrc, pDst, pGC, srcx, srcy, w, h, dstx, dsty, plane)
+    DrawablePtr	  pSrc;
+    DrawablePtr	  pDst;
+    register GC   *pGC;
+    int     	  srcx,
+		  srcy;
+    int     	  w,
+		  h;
+    int     	  dstx,
+		  dsty;
+    unsigned long  plane;
+{
+    BoxPtr	pExtents;
+    long	dx, dy;
+    int		bsrcx, bsrcy, bw, bh, bdstx, bdsty;
+    RegionPtr	winExposed = 0, pixExposed = 0;
+    SETUP_BACKING(pDst, pGC);
+
+    PROLOGUE(pGC);
+
+    if ((pSrc != pDst) ||
+	(!miBSDoCopy((WindowPtr)pSrc, pGC, srcx, srcy, w, h, dstx, dsty,
+		     plane,  pGC->ops->CopyPlane, &winExposed)))
+    {
+	/*
+	 * always copy to the backing store first, miBSDoCopy
+	 * returns FALSE if the *source* region is disjoint
+	 * from the backing store saved region.  So, copying
+	 * *to* the backing store is always safe
+	 */
+	if (pGC->clientClipType != CT_PIXMAP)
+	{
+	    /*
+	     * adjust srcx, srcy, w, h, dstx, dsty to be clipped to
+	     * the backing store.  An unnecessary optimisation,
+	     * but a useful one when GetSpans is slow.
+	     */
+	    pExtents = REGION_EXTENTS(pDst->pScreen,
+				      (RegionPtr)pBackingGC->clientClip);
+	    bsrcx = srcx;
+	    bsrcy = srcy;
+	    bw = w;
+	    bh = h;
+	    bdstx = dstx;
+	    bdsty = dsty;
+	    dx = pExtents->x1 - bdstx;
+	    if (dx > 0)
+	    {
+		bsrcx += dx;
+		bdstx += dx;
+		bw -= dx;
+	    }
+	    dy = pExtents->y1 - bdsty;
+	    if (dy > 0)
+	    {
+		bsrcy += dy;
+		bdsty += dy;
+		bh -= dy;
+	    }
+	    dx = (bdstx + bw) - pExtents->x2;
+	    if (dx > 0)
+		bw -= dx;
+	    dy = (bdsty + bh) - pExtents->y2;
+	    if (dy > 0)
+		bh -= dy;
+	    if (bw > 0 && bh > 0)
+		pixExposed = (* pBackingGC->ops->CopyPlane) (pSrc, 
+				    pBackingDrawable,
+				    pBackingGC, bsrcx, bsrcy, bw, bh,
+				    bdstx - pBackingStore->x,
+				    bdsty - pBackingStore->y, plane);
+	}
+	else
+	    pixExposed = (* pBackingGC->ops->CopyPlane) (pSrc, 
+				    pBackingDrawable,
+				    pBackingGC, srcx, srcy, w, h,
+				    dstx - pBackingStore->x,
+				    dsty - pBackingStore->y, plane);
+
+	winExposed = (* pGC->ops->CopyPlane) (pSrc, pDst, pGC, srcx, srcy, w, h,
+			      dstx, dsty, plane);
+	
+    }
+
+    /*
+     * compute the composite graphics exposure region
+     */
+    if (winExposed)
+    {
+	if (pixExposed)
+	{
+	    REGION_UNION(pDst->pScreen, winExposed, winExposed, pixExposed);
+	    REGION_DESTROY(pDst->pScreen, pixExposed);
+	}
+    } else
+	winExposed = pixExposed;
+
+    EPILOGUE (pGC);
+
+    return winExposed;
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyPoint --
+ *	Perform a PolyPoint, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyPoint (pDrawable, pGC, mode, npt, pptInit)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		mode;		/* Origin or Previous */
+    int		npt;
+    xPoint 	*pptInit;
+{
+    xPoint	  *pptCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pptCopy = (xPoint *)ALLOCATE_LOCAL(npt*sizeof(xPoint));
+    if (pptCopy)
+    {
+	copyPoints(pptInit, pptCopy, npt, mode);
+
+	(* pGC->ops->PolyPoint) (pDrawable, pGC, mode, npt, pptInit);
+
+	(* pBackingGC->ops->PolyPoint) (pBackingDrawable,
+				   pBackingGC, mode, npt, pptCopy);
+
+	DEALLOCATE_LOCAL(pptCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyLines --
+ *	Perform a Polylines, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolylines (pDrawable, pGC, mode, npt, pptInit)
+    DrawablePtr	  pDrawable;
+    GCPtr   	  pGC;
+    int	    	  mode;
+    int	    	  npt;
+    DDXPointPtr	  pptInit;
+{
+    DDXPointPtr	pptCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pptCopy = (DDXPointPtr)ALLOCATE_LOCAL(npt*sizeof(DDXPointRec));
+    if (pptCopy)
+    {
+	copyPoints(pptInit, pptCopy, npt, mode);
+
+	(* pGC->ops->Polylines)(pDrawable, pGC, mode, npt, pptInit);
+	(* pBackingGC->ops->Polylines)(pBackingDrawable,
+				  pBackingGC, mode, npt, pptCopy);
+	DEALLOCATE_LOCAL(pptCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolySegment --
+ *	Perform a PolySegment, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolySegment(pDrawable, pGC, nseg, pSegs)
+    DrawablePtr pDrawable;
+    GCPtr 	pGC;
+    int		nseg;
+    xSegment	*pSegs;
+{
+    xSegment	*pSegsCopy;
+
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pSegsCopy = (xSegment *)ALLOCATE_LOCAL(nseg*sizeof(xSegment));
+    if (pSegsCopy)
+    {
+	copyData(pSegs, pSegsCopy, nseg << 1, MoreCopy0);
+
+	(* pGC->ops->PolySegment)(pDrawable, pGC, nseg, pSegs);
+	(* pBackingGC->ops->PolySegment)(pBackingDrawable,
+				    pBackingGC, nseg, pSegsCopy);
+
+	DEALLOCATE_LOCAL(pSegsCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyRectangle --
+ *	Perform a PolyRectangle, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyRectangle(pDrawable, pGC, nrects, pRects)
+    DrawablePtr	pDrawable;
+    GCPtr	pGC;
+    int		nrects;
+    xRectangle	*pRects;
+{
+    xRectangle	*pRectsCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pRectsCopy =(xRectangle *)ALLOCATE_LOCAL(nrects*sizeof(xRectangle));
+    if (pRectsCopy)
+    {
+	copyData(pRects, pRectsCopy, nrects, MoreCopy2);
+
+	(* pGC->ops->PolyRectangle)(pDrawable, pGC, nrects, pRects);
+	(* pBackingGC->ops->PolyRectangle)(pBackingDrawable,
+				      pBackingGC, nrects, pRectsCopy);
+
+	DEALLOCATE_LOCAL(pRectsCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyArc --
+ *	Perform a PolyArc, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyArc(pDrawable, pGC, narcs, parcs)
+    DrawablePtr	pDrawable;
+    GCPtr	pGC;
+    int		narcs;
+    xArc	*parcs;
+{
+    xArc  *pArcsCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pArcsCopy = (xArc *)ALLOCATE_LOCAL(narcs*sizeof(xArc));
+    if (pArcsCopy)
+    {
+	copyData(parcs, pArcsCopy, narcs, MoreCopy4);
+
+	(* pGC->ops->PolyArc)(pDrawable, pGC, narcs, parcs);
+	(* pBackingGC->ops->PolyArc)(pBackingDrawable, pBackingGC,
+				narcs, pArcsCopy);
+
+	DEALLOCATE_LOCAL(pArcsCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSFillPolygon --
+ *	Perform a FillPolygon, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSFillPolygon(pDrawable, pGC, shape, mode, count, pPts)
+    DrawablePtr		pDrawable;
+    register GCPtr	pGC;
+    int			shape, mode;
+    register int	count;
+    DDXPointPtr		pPts;
+{
+    DDXPointPtr	pPtsCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pPtsCopy = (DDXPointPtr)ALLOCATE_LOCAL(count*sizeof(DDXPointRec));
+    if (pPtsCopy)
+    {
+	copyPoints(pPts, pPtsCopy, count, mode);
+	(* pGC->ops->FillPolygon)(pDrawable, pGC, shape, mode, count, pPts);
+	(* pBackingGC->ops->FillPolygon)(pBackingDrawable,
+				    pBackingGC, shape, mode,
+				    count, pPtsCopy);
+
+	DEALLOCATE_LOCAL(pPtsCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyFillRect --
+ *	Perform a PolyFillRect, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyFillRect(pDrawable, pGC, nrectFill, prectInit)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		nrectFill; 	/* number of rectangles to fill */
+    xRectangle	*prectInit;  	/* Pointer to first rectangle to fill */
+{
+    xRectangle	*pRectCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pRectCopy =
+	(xRectangle *)ALLOCATE_LOCAL(nrectFill*sizeof(xRectangle));
+    if (pRectCopy)
+    {
+	copyData(prectInit, pRectCopy, nrectFill, MoreCopy2);
+
+	(* pGC->ops->PolyFillRect)(pDrawable, pGC, nrectFill, prectInit);
+	(* pBackingGC->ops->PolyFillRect)(pBackingDrawable,
+				     pBackingGC, nrectFill, pRectCopy);
+
+	DEALLOCATE_LOCAL(pRectCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyFillArc --
+ *	Perform a PolyFillArc, routing output to backing-store as needed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyFillArc(pDrawable, pGC, narcs, parcs)
+    DrawablePtr	pDrawable;
+    GCPtr	pGC;
+    int		narcs;
+    xArc	*parcs;
+{
+    xArc  *pArcsCopy;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    pArcsCopy = (xArc *)ALLOCATE_LOCAL(narcs*sizeof(xArc));
+    if (pArcsCopy)
+    {
+	copyData(parcs, pArcsCopy, narcs, MoreCopy4);
+	(* pGC->ops->PolyFillArc)(pDrawable, pGC, narcs, parcs);
+	(* pBackingGC->ops->PolyFillArc)(pBackingDrawable,
+				    pBackingGC, narcs, pArcsCopy);
+	DEALLOCATE_LOCAL(pArcsCopy);
+    }
+
+    EPILOGUE (pGC);
+}
+
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyText8 --
+ *	Perform a PolyText8, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static int
+miBSPolyText8(pDrawable, pGC, x, y, count, chars)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		x, y;
+    int 	count;
+    char	*chars;
+{
+    int	    result;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    result = (* pGC->ops->PolyText8)(pDrawable, pGC, x, y, count, chars);
+    (* pBackingGC->ops->PolyText8)(pBackingDrawable, pBackingGC,
+				   x - pBackingStore->x, y - pBackingStore->y,
+				   count, chars);
+
+    EPILOGUE (pGC);
+    return result;
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyText16 --
+ *	Perform a PolyText16, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static int
+miBSPolyText16(pDrawable, pGC, x, y, count, chars)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		x, y;
+    int		count;
+    unsigned short *chars;
+{
+    int	result;
+    SETUP_BACKING (pDrawable, pGC);
+
+    PROLOGUE(pGC);
+
+    result = (* pGC->ops->PolyText16)(pDrawable, pGC, x, y, count, chars);
+    (* pBackingGC->ops->PolyText16)(pBackingDrawable, pBackingGC,
+				    x - pBackingStore->x, y - pBackingStore->y,
+				    count, chars);
+
+    EPILOGUE (pGC);
+
+    return result;
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSImageText8 --
+ *	Perform a ImageText8, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSImageText8(pDrawable, pGC, x, y, count, chars)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		x, y;
+    int		count;
+    char	*chars;
+{
+    SETUP_BACKING (pDrawable, pGC);
+    PROLOGUE(pGC);
+
+    (* pGC->ops->ImageText8)(pDrawable, pGC, x, y, count, chars);
+    (* pBackingGC->ops->ImageText8)(pBackingDrawable, pBackingGC,
+				    x - pBackingStore->x, y - pBackingStore->y,
+				    count, chars);
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSImageText16 --
+ *	Perform a ImageText16, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSImageText16(pDrawable, pGC, x, y, count, chars)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int		x, y;
+    int		count;
+    unsigned short *chars;
+{
+    SETUP_BACKING (pDrawable, pGC);
+    PROLOGUE(pGC);
+
+    (* pGC->ops->ImageText16)(pDrawable, pGC, x, y, count, chars);
+    (* pBackingGC->ops->ImageText16)(pBackingDrawable, pBackingGC,
+				    x - pBackingStore->x, y - pBackingStore->y,
+				     count, chars);
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSImageGlyphBlt --
+ *	Perform a ImageGlyphBlt, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSImageGlyphBlt(pDrawable, pGC, x, y, nglyph, ppci, pglyphBase)
+    DrawablePtr pDrawable;
+    GCPtr 	pGC;
+    int 	x, y;
+    unsigned int nglyph;
+    CharInfoPtr *ppci;		/* array of character info */
+    pointer 	pglyphBase;	/* start of array of glyphs */
+{
+    SETUP_BACKING (pDrawable, pGC);
+    PROLOGUE(pGC);
+
+    (* pGC->ops->ImageGlyphBlt)(pDrawable, pGC, x, y, nglyph, ppci,
+			     pglyphBase);
+    (* pBackingGC->ops->ImageGlyphBlt)(pBackingDrawable, pBackingGC,
+				    x - pBackingStore->x, y - pBackingStore->y,
+				       nglyph, ppci, pglyphBase);
+
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPolyGlyphBlt --
+ *	Perform a PolyGlyphBlt, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPolyGlyphBlt(pDrawable, pGC, x, y, nglyph, ppci, pglyphBase)
+    DrawablePtr pDrawable;
+    GCPtr	pGC;
+    int 	x, y;
+    unsigned int nglyph;
+    CharInfoPtr *ppci;		/* array of character info */
+    pointer	pglyphBase;	/* start of array of glyphs */
+{
+    SETUP_BACKING (pDrawable, pGC);
+    PROLOGUE(pGC);
+
+    (* pGC->ops->PolyGlyphBlt)(pDrawable, pGC, x, y, nglyph,
+			    ppci, pglyphBase);
+    (* pBackingGC->ops->PolyGlyphBlt)(pBackingDrawable, pBackingGC,
+				    x - pBackingStore->x, y - pBackingStore->y,
+				      nglyph, ppci, pglyphBase);
+    EPILOGUE (pGC);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSPushPixels --
+ *	Perform a PushPixels, routing output to backing-store as needed.
+ *
+ * Results:
+ *
+ * Side Effects:
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSPushPixels(pGC, pBitMap, pDst, w, h, x, y)
+    GCPtr	pGC;
+    PixmapPtr	pBitMap;
+    DrawablePtr pDst;
+    int		w, h, x, y;
+{
+    SETUP_BACKING (pDst, pGC);
+    PROLOGUE(pGC);
+
+    (* pGC->ops->PushPixels)(pGC, pBitMap, pDst, w, h, x, y);
+    if (pGC->miTranslate) {
+ 	x -= pDst->x;
+ 	y -= pDst->y;
+    }
+    (* pBackingGC->ops->PushPixels)(pBackingGC, pBitMap,
+			       pBackingDrawable, w, h,
+			       x - pBackingStore->x, y - pBackingStore->y);
+
+    EPILOGUE (pGC);
+}
+
+#ifdef NEED_LINEHELPER
+/*-
+ *-----------------------------------------------------------------------
+ * miBSLineHelper --
+ *
+ * Results: should never be called
+ *
+ * Side Effects: server dies
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSLineHelper()
+{
+    FatalError("miBSLineHelper called\n");
+}
+#endif
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSClearBackingStore --
+ *	Clear the given area of the backing pixmap with the background of
+ *	the window, whatever it is. If generateExposures is TRUE, generate
+ *	exposure events for the area. Note that if the area has any
+ *	part outside the saved portions of the window, we do not allow the
+ *	count in the expose events to be 0, since there will be more
+ *	expose events to come.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	Areas of pixmap are cleared and Expose events are generated.
+ *
+ *-----------------------------------------------------------------------
+ */
+static RegionPtr
+miBSClearBackingStore(pWin, x, y, w, h, generateExposures)
+    WindowPtr	  	pWin;
+    int	    	  	x;
+    int	    	  	y;
+    int	    	  	w;
+    int	    	  	h;
+    Bool    	  	generateExposures;
+{
+    RegionPtr	  	pRgn;
+    int	    	  	i;
+    miBSWindowPtr	pBackingStore;
+    ScreenPtr	  	pScreen;
+    GCPtr   	  	pGC;
+    int	    	  	ts_x_origin,
+			ts_y_origin;
+    pointer    	  	gcvalues[4];
+    unsigned long 	gcmask;
+    xRectangle	  	*rects;
+    BoxPtr  	  	pBox;
+    BoxRec  	  	box;
+    PixUnion		background;
+    char		backgroundState;
+    int			numRects;
+
+    pBackingStore = (miBSWindowPtr)pWin->backStorage;
+    pScreen = pWin->drawable.pScreen;
+
+    if ((pBackingStore->status == StatusNoPixmap) ||
+	(pBackingStore->status == StatusBadAlloc))
+	return NullRegion;
+    
+    if (w == 0)
+	w = (int) pWin->drawable.width - x;
+    if (h == 0)
+	h = (int) pWin->drawable.height - y;
+
+    box.x1 = x;
+    box.y1 = y;
+    box.x2 = x + w;
+    box.y2 = y + h;
+    pRgn = REGION_CREATE(pWin->drawable.pScreen, &box, 1);
+    if (!pRgn)
+	return NullRegion;
+    REGION_INTERSECT( pScreen, pRgn, pRgn, &pBackingStore->SavedRegion);
+
+    if (REGION_NOTEMPTY( pScreen, pRgn))
+    {
+	/*
+	 * if clearing entire window, simply make new virtual
+	 * tile.  For the root window, we also destroy the pixmap
+	 * to save a pile of memory
+	 */
+	if (x == 0 && y == 0 &&
+ 	    w == pWin->drawable.width &&
+ 	    h == pWin->drawable.height)
+	{
+	    if (!pWin->parent)
+		miDestroyBSPixmap (pWin);
+	    if (pBackingStore->status != StatusContents)
+		 miTileVirtualBS (pWin);
+	}
+
+	ts_x_origin = ts_y_origin = 0;
+
+	backgroundState = pWin->backgroundState;
+	background = pWin->background;
+	if (backgroundState == ParentRelative) {
+	    WindowPtr	pParent;
+
+	    pParent = pWin;
+	    while (pParent->backgroundState == ParentRelative) {
+		ts_x_origin -= pParent->origin.x;
+		ts_y_origin -= pParent->origin.y;
+		pParent = pParent->parent;
+	    }
+	    backgroundState = pParent->backgroundState;
+	    background = pParent->background;
+	}
+
+	if ((backgroundState != None) &&
+	    ((pBackingStore->status == StatusContents) ||
+	     !SameBackground (pBackingStore->backgroundState,
+			      pBackingStore->background,
+			      backgroundState,
+			      background)))
+	{
+	    if (!pBackingStore->pBackingPixmap)
+		miCreateBSPixmap(pWin, NullBox);
+
+	    pGC = GetScratchGC(pWin->drawable.depth, pScreen);
+	    if (pGC && pBackingStore->pBackingPixmap)
+	    {
+		/*
+		 * First take care of any ParentRelative stuff by altering the
+		 * tile/stipple origin to match the coordinates of the upper-left
+		 * corner of the first ancestor without a ParentRelative background.
+		 * This coordinate is, of course, negative.
+		 */
+	    
+		if (backgroundState == BackgroundPixel)
+		{
+		    gcvalues[0] = (pointer) background.pixel;
+		    gcvalues[1] = (pointer)FillSolid;
+		    gcmask = GCForeground|GCFillStyle;
+		}
+		else
+		{
+		    gcvalues[0] = (pointer)FillTiled;
+		    gcvalues[1] = (pointer) background.pixmap;
+		    gcmask = GCFillStyle|GCTile;
+		}
+		gcvalues[2] = (pointer)(long)(ts_x_origin - pBackingStore->x);
+		gcvalues[3] = (pointer)(long)(ts_y_origin - pBackingStore->y);
+		gcmask |= GCTileStipXOrigin|GCTileStipYOrigin;
+		DoChangeGC(pGC, gcmask, (XID *)gcvalues, TRUE);
+		ValidateGC((DrawablePtr)pBackingStore->pBackingPixmap, pGC);
+    
+		/*
+		 * Figure out the array of rectangles to fill and fill them with
+		 * PolyFillRect in the proper mode, as set in the GC above.
+		 */
+		numRects = REGION_NUM_RECTS(pRgn);
+		rects = (xRectangle *)ALLOCATE_LOCAL(numRects*sizeof(xRectangle));
+	    
+		if (rects)
+		{
+		    for (i = 0, pBox = REGION_RECTS(pRgn);
+			 i < numRects;
+			 i++, pBox++)
+		    {
+			rects[i].x = pBox->x1 - pBackingStore->x;
+			rects[i].y = pBox->y1 - pBackingStore->y;
+			rects[i].width = pBox->x2 - pBox->x1;
+			rects[i].height = pBox->y2 - pBox->y1;
+		    }
+		    (* pGC->ops->PolyFillRect) (
+				(DrawablePtr)pBackingStore->pBackingPixmap,
+				       pGC, numRects, rects);
+		    DEALLOCATE_LOCAL(rects);
+		}	
+		FreeScratchGC(pGC);
+	    }
+	}	
+
+	if (!generateExposures)
+ 	{
+	    REGION_DESTROY(pScreen, pRgn);
+	    pRgn = NULL;
+	}
+	else
+	{
+	    /*
+	     * result must be screen relative, but is currently
+	     * drawable relative.
+	     */
+	    REGION_TRANSLATE(pScreen, pRgn, pWin->drawable.x,
+			     pWin->drawable.y);
+	}
+    }
+    else
+    {
+	REGION_DESTROY( pScreen, pRgn);
+	pRgn = NULL;
+    }
+    return pRgn;
+}
+
+static void
+miBSClearBackingRegion (pWin, pRgn)
+    WindowPtr	pWin;
+    RegionPtr	pRgn;
+{
+    BoxPtr	pBox;
+    int		i;
+
+    i = REGION_NUM_RECTS(pRgn);
+    pBox = REGION_RECTS(pRgn);
+    while (i--)
+    {
+	(void) miBSClearBackingStore(pWin, pBox->x1, pBox->y1,
+					pBox->x2 - pBox->x1,
+					pBox->y2 - pBox->y1,
+					FALSE);
+	pBox++;
+    }
+}
+
+/*
+ * fill a region of the destination with virtual bits
+ *
+ * pRgn is to be translated by (x,y)
+ */
+
+static void
+miBSFillVirtualBits (pDrawable, pGC, pRgn, x, y, state, pixunion, planeMask)
+    DrawablePtr		pDrawable;
+    GCPtr		pGC;
+    RegionPtr		pRgn;
+    int			x, y;
+    int			state;
+    PixUnion		pixunion;
+    unsigned long	planeMask;
+{
+    int		i;
+    BITS32	gcmask;
+    pointer	gcval[5];
+    xRectangle	*pRect;
+    BoxPtr	pBox;
+    WindowPtr	pWin;
+    int		numRects;
+
+    if (state == None)
+	return;
+    numRects = REGION_NUM_RECTS(pRgn);
+    pRect = (xRectangle *)ALLOCATE_LOCAL(numRects * sizeof(xRectangle));
+    if (!pRect)
+	return;
+    pWin = 0;
+    if (pDrawable->type != DRAWABLE_PIXMAP)
+    {
+	pWin = (WindowPtr) pDrawable;
+	if (!pWin->backStorage)
+	    pWin = 0;
+    }
+    i = 0;
+    gcmask = 0;
+    gcval[i++] = (pointer)planeMask;
+    gcmask |= GCPlaneMask;
+    if (state == BackgroundPixel)
+    {
+	if (pGC->fgPixel != pixunion.pixel)
+	{
+	    gcval[i++] = (pointer)pixunion.pixel;
+	    gcmask |= GCForeground;
+	}
+	if (pGC->fillStyle != FillSolid)
+	{
+	    gcval[i++] = (pointer)FillSolid;
+	    gcmask |= GCFillStyle;
+	}
+    }
+    else
+    {
+	if (pGC->fillStyle != FillTiled)
+	{
+	    gcval[i++] = (pointer)FillTiled;
+	    gcmask |= GCFillStyle;
+	}
+	if (pGC->tileIsPixel || pGC->tile.pixmap != pixunion.pixmap)
+	{
+	    gcval[i++] = (pointer)pixunion.pixmap;
+	    gcmask |= GCTile;
+	}
+	if (pGC->patOrg.x != x)
+	{
+	    gcval[i++] = (pointer)(long)x;
+	    gcmask |= GCTileStipXOrigin;
+	}
+	if (pGC->patOrg.y != y)
+	{
+	    gcval[i++] = (pointer)(long)y;
+	    gcmask |= GCTileStipYOrigin;
+	}
+    }
+    if (gcmask)
+	DoChangeGC (pGC, gcmask, (XID *)gcval, 1);
+
+    if (pWin)
+	(*pWin->drawable.pScreen->DrawGuarantee) (pWin, pGC, GuaranteeVisBack);
+
+    if (pDrawable->serialNumber != pGC->serialNumber)
+	ValidateGC (pDrawable, pGC);
+
+    pBox = REGION_RECTS(pRgn);
+    for (i = numRects; --i >= 0; pBox++, pRect++)
+    {
+    	pRect->x = pBox->x1 + x;
+	pRect->y = pBox->y1 + y;
+	pRect->width = pBox->x2 - pBox->x1;
+	pRect->height = pBox->y2 - pBox->y1;
+    }
+    pRect -= numRects;
+    (*pGC->ops->PolyFillRect) (pDrawable, pGC, numRects, pRect);
+    if (pWin)
+	(*pWin->drawable.pScreen->DrawGuarantee) (pWin, pGC, GuaranteeNothing);
+    DEALLOCATE_LOCAL (pRect);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSAllocate --
+ *	Create and install backing store info for a window
+ *
+ *-----------------------------------------------------------------------
+ */
+
+static void
+miBSAllocate(pWin)
+    WindowPtr 	  pWin;
+{
+    register miBSWindowPtr  pBackingStore;
+    register ScreenPtr 	    pScreen;
+	
+    if (pWin->drawable.pScreen->backingStoreSupport == NotUseful)
+	return;
+    pScreen = pWin->drawable.pScreen;
+    if (!(pBackingStore = (miBSWindowPtr)pWin->backStorage))
+    {
+
+	pBackingStore = (miBSWindowPtr)xalloc(sizeof(miBSWindowRec));
+	if (!pBackingStore)
+	    return;
+
+	pBackingStore->pBackingPixmap = NullPixmap;
+	pBackingStore->x = 0;
+	pBackingStore->y = 0;
+	REGION_NULL( pScreen, &pBackingStore->SavedRegion);
+	pBackingStore->viewable = (char)pWin->viewable;
+	pBackingStore->status = StatusNoPixmap;
+	pBackingStore->backgroundState = None;
+	pWin->backStorage = (pointer) pBackingStore;
+    }
+	
+    /*
+     * Now want to initialize the backing pixmap and SavedRegion if
+     * necessary. The initialization consists of finding all the
+     * currently-obscured regions, by taking the inverse of the window's
+     * clip list, storing the result in SavedRegion, and exposing those
+     * areas of the window.
+     */
+
+    if (pBackingStore->status == StatusNoPixmap &&
+	((pWin->backingStore == WhenMapped && pWin->viewable) ||
+	 (pWin->backingStore == Always)))
+    {
+	BoxRec  	box;
+	RegionPtr	pSavedRegion;
+
+	pSavedRegion = &pBackingStore->SavedRegion;
+
+	box.x1 = pWin->drawable.x;
+	box.x2 = box.x1 + (int) pWin->drawable.width;
+	box.y1 = pWin->drawable.y;
+	box.y2 = pWin->drawable.y + (int) pWin->drawable.height;
+
+	REGION_INVERSE( pScreen, pSavedRegion, &pWin->clipList,  &box);
+	REGION_TRANSLATE( pScreen, pSavedRegion,
+				      -pWin->drawable.x,
+				      -pWin->drawable.y);
+#ifdef SHAPE
+	if (wBoundingShape (pWin))
+	    REGION_INTERSECT(pScreen, pSavedRegion, pSavedRegion,
+			     wBoundingShape (pWin));
+	if (wClipShape (pWin))
+	    REGION_INTERSECT(pScreen, pSavedRegion, pSavedRegion,
+			     wClipShape (pWin));
+#endif
+	/* if window is already on-screen, assume it has been drawn to */
+	if (pWin->viewable)
+	    pBackingStore->status = StatusVDirty;
+	miTileVirtualBS (pWin);
+	
+	/*
+	 * deliver all the newly available regions
+	 * as exposure events to the window
+	 */
+
+	miSendExposures(pWin, pSavedRegion, 0, 0);
+    }
+    else if (!pWin->viewable)
+    {
+        /*
+         * Turn off backing store when we're not supposed to
+         * be saving anything
+         */
+        if (pBackingStore->status != StatusNoPixmap)
+        {
+            REGION_EMPTY( pScreen, &pBackingStore->SavedRegion);
+            miDestroyBSPixmap (pWin);
+        }
+    }
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSFree --
+ *	Destroy and free all the stuff associated with the backing-store
+ *	for the given window.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	The backing pixmap and all the regions and GC's are destroyed.
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSFree(pWin)
+    WindowPtr pWin;
+{
+    miBSWindowPtr 	pBackingStore;
+    register ScreenPtr	pScreen;
+
+    pScreen = pWin->drawable.pScreen;
+
+    pBackingStore = (miBSWindowPtr)pWin->backStorage;
+    if (pBackingStore)
+    {
+	miDestroyBSPixmap (pWin);
+
+	REGION_UNINIT( pScreen, &pBackingStore->SavedRegion);
+
+	xfree(pBackingStore);
+	pWin->backStorage = NULL;
+    }
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miResizeBackingStore --
+ *	Alter the size of the backing pixmap as necessary when the
+ *	SavedRegion changes size. The contents of the old pixmap are
+ *	copied/shifted into the new/same pixmap.
+ *
+ * Results:
+ *	The new Pixmap is created as necessary.
+ *
+ * Side Effects:
+ *	The old pixmap is destroyed.
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miResizeBackingStore(
+    WindowPtr	pWin,
+    int		dx,	    /* bits are moving this far */
+    int		dy,	    /* bits are moving this far */
+    Bool	saveBits)   /* bits are useful */
+{
+    miBSWindowPtr pBackingStore;
+    PixmapPtr pBackingPixmap;
+    ScreenPtr pScreen;
+    GC	   *pGC;
+    BoxPtr  extents;
+    PixmapPtr pNewPixmap;
+    int nx, ny;
+    int	nw, nh;
+
+    pBackingStore = (miBSWindowPtr)(pWin->backStorage);
+    pBackingPixmap = pBackingStore->pBackingPixmap;
+    if (!pBackingPixmap)
+	return;
+    pScreen = pWin->drawable.pScreen;
+    extents = REGION_EXTENTS(pScreen, &pBackingStore->SavedRegion);
+    pNewPixmap = pBackingPixmap;
+
+    nw = extents->x2 - extents->x1;
+    nh = extents->y2 - extents->y1;
+
+    /* the policy here could be more sophisticated */
+    if (nw != pBackingPixmap->drawable.width ||
+	nh != pBackingPixmap->drawable.height)
+    {
+	if (!saveBits || !nw || !nh)
+	{
+	    pNewPixmap = NullPixmap;
+	    pBackingStore->status = StatusNoPixmap;
+	}
+	else
+	{
+	    pNewPixmap = (PixmapPtr)(*pScreen->CreatePixmap)
+					    (pScreen,
+					     nw, nh,
+					     pWin->drawable.depth);
+	    if (!pNewPixmap)
+	    {
+#ifdef BSEAGER
+		pBackingStore->status = StatusNoPixmap;
+#else
+		pBackingStore->status = StatusBadAlloc;
+#endif
+	    }
+	}
+    }
+    if (!pNewPixmap)
+    {
+	pBackingStore->x = 0;
+	pBackingStore->y = 0;
+    }
+    else
+    {
+    	nx = pBackingStore->x - extents->x1 + dx;
+    	ny = pBackingStore->y - extents->y1 + dy;
+    	pBackingStore->x = extents->x1;
+    	pBackingStore->y = extents->y1;
+    	
+    	if (saveBits && (pNewPixmap != pBackingPixmap || nx != 0 || ny != 0))
+    	{
+    	    pGC = GetScratchGC(pNewPixmap->drawable.depth, pScreen);
+    	    if (pGC)
+    	    {
+	    	ValidateGC((DrawablePtr)pNewPixmap, pGC);
+	    	/* if we implement a policy where the pixmap can be larger than
+		 * the region extents, we might want to optimize this copyarea
+		 * by only copying the old extents, rather than the entire
+		 * pixmap
+		 */
+	    	(*pGC->ops->CopyArea)((DrawablePtr)pBackingPixmap,
+				      (DrawablePtr)pNewPixmap, pGC,
+				      0, 0,
+				      pBackingPixmap->drawable.width,
+				      pBackingPixmap->drawable.height,
+				      nx, ny);
+	    	FreeScratchGC(pGC);
+    	    }
+    	}
+    }
+    /* SavedRegion is used in the backingGC clip; force an update */
+    pWin->drawable.serialNumber = NEXT_SERIAL_NUMBER;
+    if (pNewPixmap != pBackingPixmap)
+    {
+	(* pScreen->DestroyPixmap)(pBackingPixmap);
+	pBackingStore->pBackingPixmap = pNewPixmap;
+    }
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSSaveDoomedAreas --
+ *	Saved the areas of the given window that are about to be
+ *	obscured.  If the window has moved, pObscured is expected to
+ *	be at the new screen location and (dx,dy) is expected to be the offset
+ *	to the window's previous location.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	The region is copied from the screen into pBackingPixmap and
+ *	SavedRegion is updated.
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSSaveDoomedAreas(pWin, pObscured, dx, dy)
+    register WindowPtr pWin;
+    RegionPtr 	       pObscured;
+    int		       dx, dy;
+{
+    miBSWindowPtr 	pBackingStore;
+    ScreenPtr	  	pScreen;
+    int			x, y;
+
+    pBackingStore = (miBSWindowPtr)pWin->backStorage;
+    pScreen = pWin->drawable.pScreen;
+
+    /*
+     * If the window isn't realized, it's being unmapped, thus we don't
+     * want to save anything if backingStore isn't Always.
+     */
+    if (!pWin->realized)
+    {
+	pBackingStore->viewable = (char)pWin->viewable;
+	if (pWin->backingStore != Always)
+	{
+	    REGION_EMPTY( pScreen, &pBackingStore->SavedRegion);
+	    miDestroyBSPixmap (pWin);
+	    return;
+	}
+	if (pBackingStore->status == StatusBadAlloc)
+	    pBackingStore->status = StatusNoPixmap;
+    }
+
+    /* Don't even pretend to save anything for a virtual background None */
+    if ((pBackingStore->status == StatusVirtual) &&
+	(pBackingStore->backgroundState == None))
+	return;
+
+    if (REGION_NOTEMPTY(pScreen, pObscured))
+    {
+	BoxRec	oldExtents;
+	x = pWin->drawable.x;
+	y = pWin->drawable.y;
+	REGION_TRANSLATE(pScreen, pObscured, -x, -y);
+	oldExtents = *REGION_EXTENTS(pScreen, &pBackingStore->SavedRegion);
+	REGION_UNION( pScreen, &pBackingStore->SavedRegion,
+			   &pBackingStore->SavedRegion,
+			   pObscured);
+	/*
+	 * only save the bits if we've actually
+	 * started using backing store
+	 */
+	if (pBackingStore->status != StatusVirtual)
+	{
+	    if (!pBackingStore->pBackingPixmap)
+		miCreateBSPixmap (pWin, &oldExtents);
+	    else
+		miResizeBackingStore(pWin, 0, 0, TRUE);
+
+	    if (pBackingStore->pBackingPixmap) {
+		if (pBackingStore->x | pBackingStore->y)
+		{
+		    REGION_TRANSLATE( pScreen, pObscured,
+						  -pBackingStore->x,
+						  -pBackingStore->y);
+		    x += pBackingStore->x;
+		    y += pBackingStore->y;
+		}
+		(* pScreen->BackingStoreFuncs.SaveAreas)
+		    (pBackingStore->pBackingPixmap, pObscured,
+		     x - dx, y - dy, pWin);
+	    }
+	}
+	REGION_TRANSLATE(pScreen, pObscured, x, y);
+    }
+    else
+    {
+	if (REGION_BROKEN (pScreen, pObscured))
+	{
+	    REGION_EMPTY( pScreen, &pBackingStore->SavedRegion);
+	    miDestroyBSPixmap (pWin);
+	    return;
+	}
+    }
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSRestoreAreas --
+ *	Restore areas from backing-store that are no longer obscured.
+ *	expects prgnExposed to contain a screen-relative area.
+ *
+ * Results:
+ *	The region to generate exposure events on (which may be
+ *	different from the region to paint).
+ *
+ * Side Effects:
+ *	Areas are copied from pBackingPixmap to the screen. prgnExposed
+ *	is altered to contain the region that could not be restored from
+ *	backing-store.
+ *
+ * Notes:
+ *	This is called before sending any exposure events to the client,
+ *	and so might be called if the window has grown.  Changing the backing
+ *	pixmap doesn't require revalidating the backingGC because the
+ *	client's next output request will result in a call to ValidateGC,
+ *	since the window clip region has changed, which will in turn call
+ *	miValidateBackingStore.
+ *-----------------------------------------------------------------------
+ */
+static RegionPtr
+miBSRestoreAreas(pWin, prgnExposed)
+    register WindowPtr pWin;
+    RegionPtr prgnExposed;
+{
+    PixmapPtr pBackingPixmap;
+    miBSWindowPtr pBackingStore;
+    RegionPtr prgnSaved;
+    RegionPtr prgnRestored;
+    register ScreenPtr pScreen;
+    RegionPtr exposures = prgnExposed;
+
+    pScreen = pWin->drawable.pScreen;
+    pBackingStore = (miBSWindowPtr)pWin->backStorage;
+    pBackingPixmap = pBackingStore->pBackingPixmap;
+
+    prgnSaved = &pBackingStore->SavedRegion;
+
+    if (pBackingStore->status == StatusContents)
+    {
+	REGION_TRANSLATE(pScreen, prgnSaved, pWin->drawable.x,
+			 pWin->drawable.y);
+
+	prgnRestored = REGION_CREATE( pScreen, (BoxPtr)NULL, 1);
+	REGION_INTERSECT( pScreen, prgnRestored, prgnExposed, prgnSaved);
+	
+	/*
+	 * Since prgnExposed is no longer obscured, we no longer
+	 * will have a valid copy of it in backing-store, but there is a valid
+	 * copy of it on screen, so subtract the area we just restored from
+	 * from the area to be exposed.
+	 */
+
+	if (REGION_NOTEMPTY( pScreen, prgnRestored))
+	{
+	    REGION_SUBTRACT( pScreen, prgnSaved, prgnSaved, prgnExposed);
+	    REGION_SUBTRACT( pScreen, prgnExposed, prgnExposed, prgnRestored);
+
+	    /*
+	     * Do the actual restoration
+	     */
+	    (* pScreen->BackingStoreFuncs.RestoreAreas) (pBackingPixmap,
+					  prgnRestored,
+					  pWin->drawable.x + pBackingStore->x,
+					  pWin->drawable.y + pBackingStore->y,
+					  pWin);
+	    /*
+	     * if the saved region is completely empty, dispose of the
+	     * backing pixmap, otherwise, retranslate the saved
+	     * region to window relative
+	     */
+
+	    if (REGION_NOTEMPTY(pScreen, prgnSaved))
+	    {
+		REGION_TRANSLATE(pScreen, prgnSaved,
+					     -pWin->drawable.x,
+					     -pWin->drawable.y);
+		miResizeBackingStore(pWin, 0, 0, TRUE);
+	    }
+	    else
+		miDestroyBSPixmap (pWin);
+	}
+	else
+	    REGION_TRANSLATE(pScreen, prgnSaved,
+				-pWin->drawable.x, -pWin->drawable.y);
+	REGION_DESTROY( pScreen, prgnRestored);
+
+    }
+    else if ((pBackingStore->status == StatusVirtual) ||
+	     (pBackingStore->status == StatusVDirty))
+    {
+	REGION_TRANSLATE(pScreen, prgnSaved,
+				     pWin->drawable.x, pWin->drawable.y);
+	exposures = REGION_CREATE( pScreen, NullBox, 1);
+	if (SameBackground (pBackingStore->backgroundState,
+			    pBackingStore->background,
+			    pWin->backgroundState,
+ 			    pWin->background))
+	{
+	    REGION_SUBTRACT( pScreen, exposures, prgnExposed, prgnSaved);
+	}
+	else
+	{
+	    miTileVirtualBS(pWin);
+
+	    /* we need to expose all we have (virtually) retiled */
+	    REGION_UNION( pScreen, exposures, prgnExposed, prgnSaved);
+	}
+	REGION_SUBTRACT( pScreen, prgnSaved, prgnSaved, prgnExposed);
+	REGION_TRANSLATE(pScreen, prgnSaved,
+				     -pWin->drawable.x, -pWin->drawable.y);
+    }
+    else if (pWin->viewable && !pBackingStore->viewable &&
+	     pWin->backingStore != Always)
+    {
+	/*
+	 * The window was just mapped and nothing has been saved in
+	 * backing-store from the last time it was mapped. We want to capture
+	 * any output to regions that are already obscured but there are no
+	 * bits to snag off the screen, so we initialize things just as we did
+	 * in miBSAllocate, above.
+	 */
+	BoxRec  box;
+	
+	prgnSaved = &pBackingStore->SavedRegion;
+
+	box.x1 = pWin->drawable.x;
+	box.x2 = box.x1 + (int) pWin->drawable.width;
+	box.y1 = pWin->drawable.y;
+	box.y2 = box.y1 + (int) pWin->drawable.height;
+	
+	REGION_INVERSE( pScreen, prgnSaved, &pWin->clipList,  &box);
+	REGION_TRANSLATE( pScreen, prgnSaved,
+				      -pWin->drawable.x,
+				      -pWin->drawable.y);
+#ifdef SHAPE
+	if (wBoundingShape (pWin))
+	    REGION_INTERSECT(pScreen, prgnSaved, prgnSaved,
+			     wBoundingShape (pWin));
+	if (wClipShape (pWin))
+	    REGION_INTERSECT(pScreen, prgnSaved, prgnSaved,
+			     wClipShape (pWin));
+#endif
+	miTileVirtualBS(pWin);
+
+	exposures = REGION_CREATE( pScreen, &box, 1);
+    }
+    pBackingStore->viewable = (char)pWin->viewable;
+    return exposures;
+}
+
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSTranslateBackingStore --
+ *	Shift the backing-store in the given direction. Called when bit
+ *	gravity is shifting things around. 
+ *
+ * Results:
+ *	An occluded region of the window which should be sent exposure events.
+ *	This region should be in absolute coordinates (i.e. include
+ *	new window position).
+ *
+ * Side Effects:
+ *	If the window changed size as well as position, the backing pixmap
+ *	is resized. The contents of the backing pixmap are shifted
+ *
+ * Warning:
+ *	Bob and I have rewritten this routine quite a few times, each
+ *	time it gets a few more cases correct, and introducing some
+ *	interesting bugs.  Naturally, I think the code is correct this
+ *	time.
+ *
+ *	Let me try to explain what this routine is for:
+ *
+ *	It's called from SlideAndSizeWindow whenever a window
+ *	with backing store is resized.  There are two separate
+ *	possibilities:
+ *
+ *	a)  The window has ForgetGravity
+ *
+ *	    In this case, windx, windy will be 0 and oldClip will
+ *	    be NULL.  This indicates that all of the window contents
+ *	    currently saved offscreen should be discarded, and the
+ *	    entire window exposed.  TranslateBackingStore, then, should
+ *	    prepare a completely new backing store region based on the
+ *	    new window clipList and return that region for exposure.
+ *
+ *	b)  The window has some other gravity
+ *
+ *	    In this case, windx, windy will be set to the distance
+ *	    that the bits should move within the window.  oldClip
+ *	    will be set to the old visible portion of the window.
+ *	    TranslateBackingStore, then, should adjust the backing
+ *	    store to accommodate the portion of the existing backing
+ *	    store bits which coorespond to backing store bits which
+ *	    will still be occluded in the new configuration.  oldx,oldy
+ *	    are set to the old position of the window on the screen.
+ *
+ *	    Furthermore, in this case any contents of the screen which
+ *	    are about to become occluded should be fetched from the screen
+ *	    and placed in backing store.  This is to avoid the eventual
+ *	    occlusion by the win gravity shifting the child window bits around
+ *	    on top of this window, and potentially losing information
+ *
+ *	It's also called from SetShape, but I think (he says not
+ *	really knowing for sure) that this code will even work
+ *	in that case.
+ *-----------------------------------------------------------------------
+ */
+
+static RegionPtr
+miBSTranslateBackingStore(pWin, windx, windy, oldClip, oldx, oldy)
+    WindowPtr 	  pWin;
+    int     	  windx;	/* bit translation distance in window */
+    int     	  windy;
+    RegionPtr	  oldClip;  	/* Region being copied */
+    int     	  oldx;		/* old window position */
+    int     	  oldy;
+{
+    register miBSWindowPtr 	pBackingStore;
+    register RegionPtr 	    	pSavedRegion;
+    register RegionPtr 	    	newSaved, doomed;
+    register ScreenPtr		pScreen;
+    BoxRec			extents;
+    int     	  scrdx;	/* bit translation distance on screen */
+    int     	  scrdy;
+    int		  dx;		/* distance window moved  on screen */
+    int		  dy;
+
+    pScreen = pWin->drawable.pScreen;
+    pBackingStore = (miBSWindowPtr)(pWin->backStorage);
+    if ((pBackingStore->status == StatusNoPixmap) ||
+	(pBackingStore->status == StatusBadAlloc))
+	return NullRegion;
+
+    /*
+     * Compute the new saved region
+     */
+
+    newSaved = REGION_CREATE( pScreen, NullBox, 1);
+    extents.x1 = pWin->drawable.x;
+    extents.x2 = pWin->drawable.x + (int) pWin->drawable.width;
+    extents.y1 = pWin->drawable.y;
+    extents.y2 = pWin->drawable.y + (int) pWin->drawable.height;
+    REGION_INVERSE( pScreen, newSaved, &pWin->clipList, &extents);
+
+    REGION_TRANSLATE( pScreen, newSaved,
+			-pWin->drawable.x, -pWin->drawable.y);
+#ifdef SHAPE
+    if (wBoundingShape (pWin) || wClipShape (pWin)) {
+	if (wBoundingShape (pWin))
+	    REGION_INTERSECT( pScreen, newSaved, newSaved,
+				wBoundingShape (pWin));
+	if (wClipShape (pWin))
+	    REGION_INTERSECT( pScreen, newSaved, newSaved, wClipShape (pWin));
+    }
+#endif
+    
+    pSavedRegion = &pBackingStore->SavedRegion;
+
+    /* now find any visible areas we can save from the screen */
+    /* and then translate newSaved to old local coordinates */
+    if (oldClip)
+    {
+    	/* bit gravity makes things virtually too hard, punt */
+    	if (((windx != 0) || (windy != 0)) &&
+	    (pBackingStore->status != StatusContents))
+	    miCreateBSPixmap(pWin, NullBox);
+    
+	/*
+	 * The window is moving this far on the screen
+	 */
+    	dx = pWin->drawable.x - oldx;
+    	dy = pWin->drawable.y - oldy;
+	/*
+	 * The bits will be moving on the screen by the
+	 * amount the window is moving + the amount the
+	 * bits are moving within the window
+	 */
+    	scrdx = windx + dx;
+    	scrdy = windy + dy;
+    
+	/*
+ 	 * intersect at old bit position to discover the
+	 * bits on the screen which can be put into the
+	 * new backing store
+ 	 */
+	REGION_TRANSLATE( pScreen, oldClip, windx - oldx, windy - oldy);
+	doomed = REGION_CREATE( pScreen, NullBox, 1);
+	REGION_INTERSECT( pScreen, doomed, oldClip, newSaved);
+	REGION_TRANSLATE( pScreen, oldClip, oldx - windx, oldy - windy);
+
+	/*
+	 * Translate the old saved region to the position in the
+	 * window where it will appear to be
+	 */
+	REGION_TRANSLATE( pScreen, pSavedRegion, windx, windy);
+
+	/*
+	 * Add the old saved region to the new saved region, so
+	 * that calls to RestoreAreas will be able to fetch those
+	 * bits back
+	 */
+	REGION_UNION( pScreen, newSaved, newSaved, pSavedRegion);
+
+	/*
+	 * Swap the new saved region into the window
+	 */
+	{
+	    RegionRec	tmp;
+
+	    tmp = *pSavedRegion;
+	    *pSavedRegion = *newSaved;
+	    *newSaved = tmp;
+	}
+	miResizeBackingStore (pWin, windx, windy, TRUE);
+
+	/*
+	 * Compute the newly enabled region
+	 * of backing store.  This region will be
+	 * set to background in the backing pixmap and
+	 * sent as exposure events to the client.
+	 */
+	REGION_SUBTRACT( pScreen, newSaved, pSavedRegion, newSaved);
+
+	/*
+	 * Fetch bits which will be obscured from
+	 * the screen
+	 */
+	if (REGION_NOTEMPTY( pScreen, doomed))
+	{
+	    /*
+	     * Don't clear regions which have bits on the
+	     * screen
+	     */
+	    REGION_SUBTRACT( pScreen, newSaved, newSaved, doomed);
+
+	    /*
+	     * Make the region to SaveDoomedAreas absolute, instead
+	     * of window relative.
+	     */
+	    REGION_TRANSLATE( pScreen, doomed,
+					  pWin->drawable.x, pWin->drawable.y);
+	    (* pScreen->SaveDoomedAreas) (pWin, doomed, scrdx, scrdy);
+	}
+	
+	REGION_DESTROY(pScreen, doomed);
+
+    	/*
+ 	 * and clear whatever there is that's new
+ 	 */
+    	if (REGION_NOTEMPTY( pScreen, newSaved))
+    	{
+	    miBSClearBackingRegion (pWin, newSaved);
+	    /*
+	     * Make the exposed region absolute
+	     */
+	    REGION_TRANSLATE(pScreen, newSaved,
+				     	 pWin->drawable.x,
+				     	 pWin->drawable.y);
+    	}
+    	else
+    	{
+	    REGION_DESTROY(pScreen, newSaved);
+	    newSaved = NullRegion;
+    	}
+    }
+    else
+    {
+	/*
+	 * ForgetGravity: just reset backing store and
+	 * expose the whole mess
+	 */
+	REGION_COPY( pScreen, pSavedRegion, newSaved);
+	REGION_TRANSLATE( pScreen, newSaved,
+				      pWin->drawable.x, pWin->drawable.y);
+
+	miResizeBackingStore (pWin, 0, 0, FALSE);
+	(void) miBSClearBackingStore (pWin, 0, 0, 0, 0, FALSE);
+    }
+
+    return newSaved;
+}
+
+/*
+ * Inform the backing store layer that you are about to validate
+ * a gc with a window, and that subsequent output to the window
+ * is (or is not) guaranteed to be already clipped to the visible
+ * regions of the window.
+ */
+
+static void
+miBSDrawGuarantee (pWin, pGC, guarantee)
+    WindowPtr	pWin;
+    GCPtr	pGC;
+    int		guarantee;
+{
+    miBSGCPtr 	pPriv;
+
+    if (pWin->backStorage)
+    {
+	pPriv = (miBSGCPtr)pGC->devPrivates[miBSGCIndex].ptr;
+	if (!pPriv)
+	    (void) miBSCreateGCPrivate (pGC);
+	pPriv = (miBSGCPtr)pGC->devPrivates[miBSGCIndex].ptr;
+	if (pPriv)
+	{
+	    /*
+	     * XXX KLUDGE ALERT
+	     *
+	     * when the GC is Cheap pPriv will point
+	     * at some device's gc func structure.  guarantee
+	     * will point at the ChangeGC entry of that struct
+	     * and will never match a valid guarantee value.
+	     */
+	    switch (pPriv->guarantee)
+	    {
+	    case GuaranteeNothing:
+	    case GuaranteeVisBack:
+		pPriv->guarantee = guarantee;
+		break;
+	    }
+	}
+    }
+}
+
+#define noBackingCopy (GCGraphicsExposures|GCClipXOrigin|GCClipYOrigin| \
+		       GCClipMask|GCSubwindowMode| \
+		       GCTileStipXOrigin|GCTileStipYOrigin)
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSValidateGC --
+ *	Wrapper around output-library's ValidateGC routine
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *
+ * Notes:
+ *	The idea here is to perform several functions:
+ *	    - All the output calls must be intercepted and routed to
+ *	      backing-store as necessary.
+ *	    - pGC in the window's devBackingStore must be set up with the
+ *	      clip list appropriate for writing to pBackingPixmap (i.e.
+ *	      the inverse of the window's clipList intersected with the
+ *	      clientClip of the GC). Since the destination for this GC is
+ *	      a pixmap, it is sufficient to set the clip list as its
+ *	      clientClip.
+ *-----------------------------------------------------------------------
+ */
+
+static void
+miBSValidateGC (pGC, stateChanges, pDrawable)
+    GCPtr   	  pGC;
+    unsigned long stateChanges;
+    DrawablePtr   pDrawable;
+{
+    GCPtr   	  	pBackingGC;
+    miBSWindowPtr	pWindowPriv = NULL;
+    miBSGCPtr		pPriv;
+    WindowPtr		pWin;
+    int			lift_functions;
+    RegionPtr		backingCompositeClip = NULL;
+
+    if (pDrawable->type != DRAWABLE_PIXMAP)
+    {
+        pWin = (WindowPtr) pDrawable;
+	pWindowPriv = (miBSWindowPtr) pWin->backStorage;
+	lift_functions = (pWindowPriv == (miBSWindowPtr) NULL);
+    }
+    else
+    {
+        pWin = (WindowPtr) NULL;
+	lift_functions = TRUE;
+    }
+
+    pPriv = (miBSGCPtr)pGC->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGC, pPriv);
+
+    (*pGC->funcs->ValidateGC) (pGC, stateChanges, pDrawable);
+
+    /*
+     * rewrap funcs and ops as Validate may have changed them
+     */
+
+    pPriv->wrapFuncs = pGC->funcs;
+    pPriv->wrapOps = pGC->ops;
+
+    if (!lift_functions && ((pPriv->guarantee == GuaranteeVisBack) ||
+                            (pWindowPriv->status == StatusNoPixmap) ||
+                            (pWindowPriv->status == StatusBadAlloc)))
+        lift_functions = TRUE;
+
+    /*
+     * check to see if a new backingCompositeClip region must
+     * be generated
+     */
+
+    if (!lift_functions && 
+        ((pDrawable->serialNumber != pPriv->serialNumber) ||
+	 (stateChanges&(GCClipXOrigin|GCClipYOrigin|GCClipMask|GCSubwindowMode))))
+    {
+	if (REGION_NOTEMPTY(pGC->pScreen, &pWindowPriv->SavedRegion))
+ 	{
+	    backingCompositeClip = REGION_CREATE(pGC->pScreen, NULL, 1);
+	    if ((pGC->clientClipType == CT_NONE) || 
+		(pGC->clientClipType == CT_PIXMAP))
+	    {
+		REGION_COPY(pGC->pScreen, backingCompositeClip,
+					     &pWindowPriv->SavedRegion); 
+	    }
+	    else
+	    {
+		/*
+		 * Make a new copy of the client clip, translated to
+		 * its proper origin.
+		 */
+
+		REGION_COPY(pGC->pScreen, backingCompositeClip,
+				pGC->clientClip);
+		REGION_TRANSLATE(pGC->pScreen, backingCompositeClip,
+						  pGC->clipOrg.x,
+						  pGC->clipOrg.y);
+		REGION_INTERSECT(pGC->pScreen, backingCompositeClip,
+					backingCompositeClip,
+					&pWindowPriv->SavedRegion);
+	    }
+	    if (pGC->subWindowMode == IncludeInferiors)
+ 	    {
+		RegionPtr translatedClip;
+
+		/* XXX
+		 * any output in IncludeInferiors mode will not
+		 * be redirected to Inferiors backing store.  This
+		 * can be fixed only at great cost to the shadow routines.
+		 */
+		translatedClip = NotClippedByChildren (pWin);
+		REGION_TRANSLATE(pGC->pScreen, translatedClip,
+						  -pDrawable->x,
+						  -pDrawable->y);
+		REGION_SUBTRACT(pGC->pScreen, backingCompositeClip,
+				backingCompositeClip, translatedClip);
+		REGION_DESTROY(pGC->pScreen, translatedClip);
+	    }
+	    if (!REGION_NOTEMPTY(pGC->pScreen, backingCompositeClip))
+		lift_functions = TRUE;
+	}
+ 	else
+ 	{
+	    lift_functions = TRUE;
+	}
+
+	/* Reset the status when drawing to an unoccluded window so that
+	 * future SaveAreas will actually copy bits from the screen.  Note that
+	 * output to root window in IncludeInferiors mode will not cause this
+	 * to change.  This causes all transient graphics by the window
+	 * manager to the root window to not enable backing store.
+	 */
+	if (lift_functions && (pWindowPriv->status == StatusVirtual) &&
+	    (pWin->parent || pGC->subWindowMode != IncludeInferiors))
+	    pWindowPriv->status = StatusVDirty;
+    }
+
+    /*
+     * if no backing store has been allocated, and it's needed,
+     * create it now.
+     */
+
+    if (!lift_functions && !pWindowPriv->pBackingPixmap)
+    {
+	miCreateBSPixmap (pWin, NullBox);
+	if (!pWindowPriv->pBackingPixmap)
+	    lift_functions = TRUE;
+    }
+    
+    /*
+     * create the backing GC if needed, lift functions
+     * if the creation fails
+     */
+
+    if (!lift_functions && !pPriv->pBackingGC)
+    {
+	int status;
+	XID noexpose = xFalse;
+
+	/* We never want ops with the backingGC to generate GraphicsExpose */
+	pBackingGC = CreateGC ((DrawablePtr)pWindowPriv->pBackingPixmap,
+			       GCGraphicsExposures, &noexpose, &status);
+	if (status != Success)
+	    lift_functions = TRUE;
+	else
+	    pPriv->pBackingGC = pBackingGC;
+    }
+
+    pBackingGC = pPriv->pBackingGC;
+
+    pPriv->stateChanges |= stateChanges;
+
+    if (lift_functions)
+    {
+	if (backingCompositeClip)
+	    REGION_DESTROY( pGC->pScreen, backingCompositeClip);
+
+	/* unwrap the GC again */
+	miBSDestroyGCPrivate (pGC);
+
+	return;
+    }
+
+    /*
+     * the rest of this function gets the pBackingGC
+     * into shape for possible draws
+     */
+
+    pPriv->stateChanges &= ~noBackingCopy;
+    if (pPriv->stateChanges)
+	CopyGC(pGC, pBackingGC, pPriv->stateChanges);
+    if ((pGC->patOrg.x - pWindowPriv->x) != pBackingGC->patOrg.x ||
+	(pGC->patOrg.y - pWindowPriv->y) != pBackingGC->patOrg.y)
+    {
+	XID vals[2];
+	vals[0] = pGC->patOrg.x - pWindowPriv->x;
+	vals[1] = pGC->patOrg.y - pWindowPriv->y;
+	DoChangeGC(pBackingGC, GCTileStipXOrigin|GCTileStipYOrigin, vals, 0);
+    }
+    pPriv->stateChanges = 0;
+
+    if (backingCompositeClip)
+    {
+	XID vals[2];
+
+	if (pGC->clientClipType == CT_PIXMAP)
+	{
+	    (*pBackingGC->funcs->CopyClip)(pBackingGC, pGC);
+	    REGION_TRANSLATE(pGC->pScreen, backingCompositeClip,
+					-pGC->clipOrg.x, -pGC->clipOrg.y);
+	    vals[0] = pGC->clipOrg.x - pWindowPriv->x;
+	    vals[1] = pGC->clipOrg.y - pWindowPriv->y;
+	    DoChangeGC(pBackingGC, GCClipXOrigin|GCClipYOrigin, vals, 0);
+	    (* pGC->pScreen->BackingStoreFuncs.SetClipmaskRgn)
+		(pBackingGC, backingCompositeClip);
+	    REGION_DESTROY( pGC->pScreen, backingCompositeClip);
+	}
+	else
+	{
+	    vals[0] = -pWindowPriv->x;
+	    vals[1] = -pWindowPriv->y;
+	    DoChangeGC(pBackingGC, GCClipXOrigin|GCClipYOrigin, vals, 0);
+	    (*pBackingGC->funcs->ChangeClip) (pBackingGC, CT_REGION, backingCompositeClip, 0);
+	}
+	pPriv->serialNumber = pDrawable->serialNumber;
+    }
+    
+    if (pWindowPriv->pBackingPixmap->drawable.serialNumber
+    	!= pBackingGC->serialNumber)
+    {
+	ValidateGC((DrawablePtr)pWindowPriv->pBackingPixmap, pBackingGC);
+    }
+
+    if (pBackingGC->clientClip == 0)
+    	ErrorF ("backing store clip list nil");
+
+    FUNC_EPILOGUE (pGC, pPriv);
+}
+
+static void
+miBSChangeGC (pGC, mask)
+    GCPtr   pGC;
+    unsigned long   mask;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pGC)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGC, pPriv);
+
+    (*pGC->funcs->ChangeGC) (pGC, mask);
+
+    FUNC_EPILOGUE (pGC, pPriv);
+}
+
+static void
+miBSCopyGC (pGCSrc, mask, pGCDst)
+    GCPtr   pGCSrc, pGCDst;
+    unsigned long   mask;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pGCDst)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGCDst, pPriv);
+
+    (*pGCDst->funcs->CopyGC) (pGCSrc, mask, pGCDst);
+
+    FUNC_EPILOGUE (pGCDst, pPriv);
+}
+
+static void
+miBSDestroyGC (pGC)
+    GCPtr   pGC;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pGC)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGC, pPriv);
+
+    if (pPriv->pBackingGC)
+	FreeGC(pPriv->pBackingGC, (GContext)0);
+
+    (*pGC->funcs->DestroyGC) (pGC);
+
+    FUNC_EPILOGUE (pGC, pPriv);
+
+    xfree(pPriv);
+}
+
+static void
+miBSChangeClip(pGC, type, pvalue, nrects)
+    GCPtr	pGC;
+    int		type;
+    pointer	pvalue;
+    int		nrects;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pGC)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGC, pPriv);
+
+    (* pGC->funcs->ChangeClip)(pGC, type, pvalue, nrects);
+
+    FUNC_EPILOGUE (pGC, pPriv);
+}
+
+static void
+miBSCopyClip(pgcDst, pgcSrc)
+    GCPtr pgcDst, pgcSrc;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pgcDst)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pgcDst, pPriv);
+
+    (* pgcDst->funcs->CopyClip)(pgcDst, pgcSrc);
+
+    FUNC_EPILOGUE (pgcDst, pPriv);
+}
+
+static void
+miBSDestroyClip(pGC)
+    GCPtr	pGC;
+{
+    miBSGCPtr	pPriv = (miBSGCPtr) (pGC)->devPrivates[miBSGCIndex].ptr;
+
+    FUNC_PROLOGUE (pGC, pPriv);
+
+    (* pGC->funcs->DestroyClip)(pGC);
+
+    FUNC_EPILOGUE (pGC, pPriv);
+}
+
+static void
+miDestroyBSPixmap (pWin)
+    WindowPtr	pWin;
+{
+    miBSWindowPtr	pBackingStore;
+    ScreenPtr		pScreen;
+    
+    pScreen = pWin->drawable.pScreen;
+    pBackingStore = (miBSWindowPtr) pWin->backStorage;
+    if (pBackingStore->pBackingPixmap)
+	(* pScreen->DestroyPixmap)(pBackingStore->pBackingPixmap);
+    pBackingStore->pBackingPixmap = NullPixmap;
+    pBackingStore->x = 0;
+    pBackingStore->y = 0;
+    if (pBackingStore->backgroundState == BackgroundPixmap)
+	(* pScreen->DestroyPixmap)(pBackingStore->background.pixmap);
+    pBackingStore->backgroundState = None;
+    pBackingStore->status = StatusNoPixmap;
+    pWin->drawable.serialNumber = NEXT_SERIAL_NUMBER;
+}
+
+static void
+miTileVirtualBS (pWin)
+    WindowPtr	pWin;
+{
+    miBSWindowPtr	pBackingStore;
+
+    pBackingStore = (miBSWindowPtr) pWin->backStorage;
+    if (pBackingStore->backgroundState == BackgroundPixmap)
+ 	(* pWin->drawable.pScreen->DestroyPixmap)
+	    (pBackingStore->background.pixmap);
+    pBackingStore->backgroundState = pWin->backgroundState;
+    pBackingStore->background = pWin->background;
+    if (pBackingStore->backgroundState == BackgroundPixmap)
+	pBackingStore->background.pixmap->refcnt++;
+
+    if (pBackingStore->status != StatusVDirty)
+	pBackingStore->status = StatusVirtual;
+
+    /*
+     * punt parent relative tiles and do it now
+     */
+    if (pBackingStore->backgroundState == ParentRelative)
+	miCreateBSPixmap (pWin, NullBox);
+}
+
+#ifdef DEBUG
+static int BSAllocationsFailed = 0;
+#define FAILEDSIZE	32
+static struct { int w, h; } failedRecord[FAILEDSIZE];
+static int failedIndex;
+#endif
+
+static void
+miCreateBSPixmap (pWin, pExtents)
+    WindowPtr	pWin;
+    BoxPtr	pExtents;
+{
+    miBSWindowPtr	pBackingStore;
+    ScreenPtr		pScreen;
+    PixUnion		background;
+    char		backgroundState = 0;
+    BoxPtr		extents;
+    Bool		backSet;
+
+    pScreen = pWin->drawable.pScreen;
+    pBackingStore = (miBSWindowPtr) pWin->backStorage;
+    if (pBackingStore->status == StatusBadAlloc)
+	return;
+    backSet = ((pBackingStore->status == StatusVirtual) ||
+	       (pBackingStore->status == StatusVDirty));
+
+    extents = REGION_EXTENTS( pScreen, &pBackingStore->SavedRegion);
+
+    if (!pBackingStore->pBackingPixmap &&
+	extents->x2 != extents->x1 &&
+	extents->y2 != extents->y1)
+    {
+	/* the policy here could be more sophisticated */
+	pBackingStore->x = extents->x1;
+	pBackingStore->y = extents->y1;
+	pBackingStore->pBackingPixmap =
+    	    (PixmapPtr)(* pScreen->CreatePixmap)
+			   (pScreen,
+			    extents->x2 - extents->x1,
+			    extents->y2 - extents->y1,
+			    pWin->drawable.depth);
+    }
+    if (!pBackingStore->pBackingPixmap)
+    {
+#ifdef DEBUG
+	BSAllocationsFailed++;
+	/*
+	 * record failed allocations
+	 */
+	failedRecord[failedIndex].w = pWin->drawable.width;
+	failedRecord[failedIndex].h = pWin->drawable.height;
+	failedIndex++;
+	if (failedIndex == FAILEDSIZE)
+		failedIndex = 0;
+#endif
+#ifdef BSEAGER
+	pBackingStore->status = StatusNoPixmap;
+#else
+	pBackingStore->status = StatusBadAlloc;
+#endif
+	return;
+    }
+
+    pBackingStore->status = StatusContents;
+
+    if (backSet)
+    {
+	backgroundState = pWin->backgroundState;
+	background = pWin->background;
+    
+	pWin->backgroundState = pBackingStore->backgroundState;
+	pWin->background = pBackingStore->background;
+	if (pWin->backgroundState == BackgroundPixmap)
+	    pWin->background.pixmap->refcnt++;
+    }
+
+    if (!pExtents)
+	pExtents = extents;
+
+    if (pExtents->y1 != pExtents->y2)
+    {
+	RegionPtr exposed;
+
+	exposed = miBSClearBackingStore(pWin,
+			      pExtents->x1, pExtents->y1,
+			      pExtents->x2 - pExtents->x1,
+			      pExtents->y2 - pExtents->y1,
+			      !backSet);
+	if (exposed)
+	{
+	    miSendExposures(pWin, exposed, pWin->drawable.x, pWin->drawable.y);
+	    REGION_DESTROY( pScreen, exposed);
+	}
+    }
+
+    if (backSet)
+    {
+	if (pWin->backgroundState == BackgroundPixmap)
+	    (* pScreen->DestroyPixmap) (pWin->background.pixmap);
+	pWin->backgroundState = backgroundState;
+	pWin->background = background;
+	if (pBackingStore->backgroundState == BackgroundPixmap)
+	    (* pScreen->DestroyPixmap) (pBackingStore->background.pixmap);
+	pBackingStore->backgroundState = None;
+    }
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miBSExposeCopy --
+ *	Handle the restoration of areas exposed by graphics operations.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	prgnExposed has the areas exposed from backing-store removed
+ *	from it.
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miBSExposeCopy (pSrc, pDst, pGC, prgnExposed, srcx, srcy, dstx, dsty, plane)
+    WindowPtr	  	pSrc;
+    DrawablePtr	  	pDst;
+    GCPtr   	  	pGC;
+    RegionPtr	  	prgnExposed;
+    int	    	  	srcx, srcy;
+    int	    	  	dstx, dsty;
+    unsigned long 	plane;
+{
+    RegionRec	  	tempRgn;
+    miBSWindowPtr	pBackingStore;
+    CopyPlaneProcPtr 	copyProc;
+    GCPtr		pScratchGC;
+    register BoxPtr	pBox;
+    register int  	i;
+    register int  	dx, dy;
+    BITS32		gcMask;
+
+    if (!REGION_NOTEMPTY(pGC->pScreen, prgnExposed))
+	return;
+    pBackingStore = (miBSWindowPtr)pSrc->backStorage;
+    
+    if ((pBackingStore->status == StatusNoPixmap) ||
+	(pBackingStore->status == StatusBadAlloc))
+    	return;
+
+    REGION_NULL( pGC->pScreen, &tempRgn);
+    REGION_INTERSECT( pGC->pScreen, &tempRgn, prgnExposed,
+				 &pBackingStore->SavedRegion);
+    REGION_SUBTRACT( pGC->pScreen, prgnExposed, prgnExposed, &tempRgn);
+
+    if (plane != 0) {
+	copyProc = pGC->ops->CopyPlane;
+    } else {
+	copyProc = (CopyPlaneProcPtr)pGC->ops->CopyArea;
+    }
+    
+    dx = dstx - srcx;
+    dy = dsty - srcy;
+    
+    switch (pBackingStore->status) {
+    case StatusVirtual:
+    case StatusVDirty:
+	pScratchGC = GetScratchGC (pDst->depth, pDst->pScreen);
+	if (pScratchGC)
+	{
+	    gcMask = 0;
+	    if (pGC->alu != pScratchGC->alu)
+	    	gcMask = GCFunction;
+	    if (pGC->planemask != pScratchGC->planemask)
+	    	gcMask |= GCPlaneMask;
+	    if (gcMask)
+	    	CopyGC (pGC, pScratchGC, gcMask);
+	    miBSFillVirtualBits (pDst, pScratchGC, &tempRgn, dx, dy,
+				 (int) pBackingStore->backgroundState,
+				 pBackingStore->background,
+				 ~0L);
+	    FreeScratchGC (pScratchGC);
+	}
+	break;
+    case StatusContents:
+	for (i = REGION_NUM_RECTS(&tempRgn), pBox = REGION_RECTS(&tempRgn);
+	     --i >= 0;
+	     pBox++)
+	{
+	    (* copyProc) (&(pBackingStore->pBackingPixmap->drawable), pDst, pGC,
+			  pBox->x1 - pBackingStore->x,
+			  pBox->y1 - pBackingStore->y,
+			  pBox->x2 - pBox->x1, pBox->y2 - pBox->y1,
+			  pBox->x1 + dx, pBox->y1 + dy, plane);
+	}
+	break;
+    }
+    REGION_UNINIT( pGC->pScreen, &tempRgn);
+}