Used synchronise script to update files

1 files changed, 1604 insertions, 1604 deletions

diff --git a/libX11/src/Region.c b/libX11/src/Region.c
index 3003ac52a..41047b242 100644
--- a/libX11/src/Region.c
+++ b/libX11/src/Region.c
@@ -1,1604 +1,1604 @@
-/************************************************************************

-

-Copyright 1987, 1988, 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, 1988 by Digital Equipment Corporation, Maynard, Massachusetts.

-

-                        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 of Digital not be

-used in advertising or publicity pertaining to distribution of the

-software without specific, written prior permission.

-

-DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING

-ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL

-DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR

-ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,

-WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,

-ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

-SOFTWARE.

-

-************************************************************************/

-/*

- * The functions in this file implement the Region abstraction, similar to one

- * used in the X11 sample server. A Region is simply an area, as the name

- * implies, and is implemented as a "y-x-banded" array of rectangles. To

- * explain: Each Region is made up of a certain number of rectangles sorted

- * by y coordinate first, and then by x coordinate.

- *

- * Furthermore, the rectangles are banded such that every rectangle with a

- * given upper-left y coordinate (y1) will have the same lower-right y

- * coordinate (y2) and vice versa. If a rectangle has scanlines in a band, it

- * will span the entire vertical distance of the band. This means that some

- * areas that could be merged into a taller rectangle will be represented as

- * several shorter rectangles to account for shorter rectangles to its left

- * or right but within its "vertical scope".

- *

- * An added constraint on the rectangles is that they must cover as much

- * horizontal area as possible. E.g. no two rectangles in a band are allowed

- * to touch.

- *

- * Whenever possible, bands will be merged together to cover a greater vertical

- * distance (and thus reduce the number of rectangles). Two bands can be merged

- * only if the bottom of one touches the top of the other and they have

- * rectangles in the same places (of the same width, of course). This maintains

- * the y-x-banding that's so nice to have...

- */

-

-#ifdef HAVE_CONFIG_H

-#include <config.h>

-#endif

-#include "Xlibint.h"

-#include "Xutil.h"

-#include <X11/Xregion.h>

-#include "poly.h"

-

-#ifdef DEBUG

-#include <stdio.h>

-#define assert(expr) {if (!(expr)) fprintf(stderr,\

-"Assertion failed file %s, line %d: expr\n", __FILE__, __LINE__); }

-#else

-#define assert(expr)

-#endif

-

-typedef int (*overlapProcp)(

-        register Region     pReg,

-        register BoxPtr     r1,

-        BoxPtr              r1End,

-        register BoxPtr     r2,

-        BoxPtr              r2End,

-        short               y1,

-        short               y2);

-

-typedef int (*nonOverlapProcp)(

-    register Region     pReg,

-    register BoxPtr     r,

-    BoxPtr              rEnd,

-    register short      y1,

-    register short      y2);

-

-static void miRegionOp(

-    register Region 	newReg,	    	    	/* Place to store result */

-    Region	  	reg1,	    	    	/* First region in operation */

-    Region	  	reg2,	    	    	/* 2d region in operation */

-    int    	  	(*overlapFunc)(

-        register Region     pReg,

-        register BoxPtr     r1,

-        BoxPtr              r1End,

-        register BoxPtr     r2,

-        BoxPtr              r2End,

-        short               y1,

-        short               y2),                /* Function to call for over-

-						 * lapping bands */

-    int    	  	(*nonOverlap1Func)(

-        register Region     pReg,

-        register BoxPtr     r,

-        BoxPtr              rEnd,

-        register short      y1,

-        register short      y2),                /* Function to call for non-

-						 * overlapping bands in region

-						 * 1 */

-    int    	  	(*nonOverlap2Func)(

-        register Region     pReg,

-        register BoxPtr     r,

-        BoxPtr              rEnd,

-        register short      y1,

-        register short      y2));               /* Function to call for non-

-						 * overlapping bands in region

-						 * 2 */

-

-

-/*	Create a new empty region	*/

-Region

-XCreateRegion(void)

-{

-    Region temp;

-

-    if (! (temp = ( Region )Xmalloc( (unsigned) sizeof( REGION ))))

-	return (Region) NULL;

-    if (! (temp->rects = ( BOX * )Xmalloc( (unsigned) sizeof( BOX )))) {

-	Xfree((char *) temp);

-	return (Region) NULL;

-    }

-    temp->numRects = 0;

-    temp->extents.x1 = 0;

-    temp->extents.y1 = 0;

-    temp->extents.x2 = 0;

-    temp->extents.y2 = 0;

-    temp->size = 1;

-    return( temp );

-}

-

-int

-XClipBox(

-    Region r,

-    XRectangle *rect)

-{

-    rect->x = r->extents.x1;

-    rect->y = r->extents.y1;

-    rect->width = r->extents.x2 - r->extents.x1;

-    rect->height = r->extents.y2 - r->extents.y1;

-    return 1;

-}

-

-int

-XUnionRectWithRegion(

-    register XRectangle *rect,

-    Region source, Region dest)

-{

-    REGION region;

-

-    if (!rect->width || !rect->height)

-	return 0;

-    region.rects = &region.extents;

-    region.numRects = 1;

-    region.extents.x1 = rect->x;

-    region.extents.y1 = rect->y;

-    region.extents.x2 = rect->x + rect->width;

-    region.extents.y2 = rect->y + rect->height;

-    region.size = 1;

-

-    return XUnionRegion(&region, source, dest);

-}

-

-/*-

- *-----------------------------------------------------------------------

- * miSetExtents --

- *	Reset the extents of a region to what they should be. Called by

- *	miSubtract and miIntersect b/c they can't figure it out along the

- *	way or do so easily, as miUnion can.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	The region's 'extents' structure is overwritten.

- *

- *-----------------------------------------------------------------------

- */

-static void

-miSetExtents (

-    Region	  	pReg)

-{

-    register BoxPtr	pBox,

-			pBoxEnd,

-			pExtents;

-

-    if (pReg->numRects == 0)

-    {

-	pReg->extents.x1 = 0;

-	pReg->extents.y1 = 0;

-	pReg->extents.x2 = 0;

-	pReg->extents.y2 = 0;

-	return;

-    }

-

-    pExtents = &pReg->extents;

-    pBox = pReg->rects;

-    pBoxEnd = &pBox[pReg->numRects - 1];

-

-    /*

-     * Since pBox is the first rectangle in the region, it must have the

-     * smallest y1 and since pBoxEnd is the last rectangle in the region,

-     * it must have the largest y2, because of banding. Initialize x1 and

-     * x2 from  pBox and pBoxEnd, resp., as good things to initialize them

-     * to...

-     */

-    pExtents->x1 = pBox->x1;

-    pExtents->y1 = pBox->y1;

-    pExtents->x2 = pBoxEnd->x2;

-    pExtents->y2 = pBoxEnd->y2;

-

-    assert(pExtents->y1 < pExtents->y2);

-    while (pBox <= pBoxEnd)

-    {

-	if (pBox->x1 < pExtents->x1)

-	{

-	    pExtents->x1 = pBox->x1;

-	}

-	if (pBox->x2 > pExtents->x2)

-	{

-	    pExtents->x2 = pBox->x2;

-	}

-	pBox++;

-    }

-    assert(pExtents->x1 < pExtents->x2);

-}

-

-int

-XSetRegion(

-    Display *dpy,

-    GC gc,

-    register Region r)

-{

-    register int i;

-    register XRectangle *xr, *pr;

-    register BOX *pb;

-    unsigned long total;

-

-    LockDisplay (dpy);

-    total = r->numRects * sizeof (XRectangle);

-    if ((xr = (XRectangle *) _XAllocTemp(dpy, total))) {

-	for (pr = xr, pb = r->rects, i = r->numRects; --i >= 0; pr++, pb++) {

-	    pr->x = pb->x1;

-	    pr->y = pb->y1;

-	    pr->width = pb->x2 - pb->x1;

-	    pr->height = pb->y2 - pb->y1;

-	}

-    }

-    if (xr || !r->numRects)

-	_XSetClipRectangles(dpy, gc, 0, 0, xr, r->numRects, YXBanded);

-    if (xr)

-	_XFreeTemp(dpy, (char *)xr, total);

-    UnlockDisplay(dpy);

-    SyncHandle();

-    return 1;

-}

-

-int

-XDestroyRegion(

-    Region r)

-{

-    Xfree( (char *) r->rects );

-    Xfree( (char *) r );

-    return 1;

-}

-

-

-/* TranslateRegion(pRegion, x, y)

-   translates in place

-   added by raymond

-*/

-

-int

-XOffsetRegion(

-    register Region pRegion,

-    register int x,

-    register int y)

-{

-    register int nbox;

-    register BOX *pbox;

-

-    pbox = pRegion->rects;

-    nbox = pRegion->numRects;

-

-    while(nbox--)

-    {

-	pbox->x1 += x;

-	pbox->x2 += x;

-	pbox->y1 += y;

-	pbox->y2 += y;

-	pbox++;

-    }

-    pRegion->extents.x1 += x;

-    pRegion->extents.x2 += x;

-    pRegion->extents.y1 += y;

-    pRegion->extents.y2 += y;

-    return 1;

-}

-

-/*

-   Utility procedure Compress:

-   Replace r by the region r', where

-     p in r' iff (Quantifer m <= dx) (p + m in r), and

-     Quantifier is Exists if grow is TRUE, For all if grow is FALSE, and

-     (x,y) + m = (x+m,y) if xdir is TRUE; (x,y+m) if xdir is FALSE.

-

-   Thus, if xdir is TRUE and grow is FALSE, r is replaced by the region

-   of all points p such that p and the next dx points on the same

-   horizontal scan line are all in r.  We do this using by noting

-   that p is the head of a run of length 2^i + k iff p is the head

-   of a run of length 2^i and p+2^i is the head of a run of length

-   k. Thus, the loop invariant: s contains the region corresponding

-   to the runs of length shift.  r contains the region corresponding

-   to the runs of length 1 + dxo & (shift-1), where dxo is the original

-   value of dx.  dx = dxo & ~(shift-1).  As parameters, s and t are

-   scratch regions, so that we don't have to allocate them on every

-   call.

-*/

-

-#define ZOpRegion(a,b,c) if (grow) XUnionRegion(a,b,c); \

-			 else XIntersectRegion(a,b,c)

-#define ZShiftRegion(a,b) if (xdir) XOffsetRegion(a,b,0); \

-			  else XOffsetRegion(a,0,b)

-#define ZCopyRegion(a,b) XUnionRegion(a,a,b)

-

-static void

-Compress(

-    Region r, Region s, Region t,

-    register unsigned dx,

-    register int xdir, register int grow)

-{

-    register unsigned shift = 1;

-

-    ZCopyRegion(r, s);

-    while (dx) {

-        if (dx & shift) {

-            ZShiftRegion(r, -(int)shift);

-            ZOpRegion(r, s, r);

-            dx -= shift;

-            if (!dx) break;

-        }

-        ZCopyRegion(s, t);

-        ZShiftRegion(s, -(int)shift);

-        ZOpRegion(s, t, s);

-        shift <<= 1;

-    }

-}

-

-#undef ZOpRegion

-#undef ZShiftRegion

-#undef ZCopyRegion

-

-int

-XShrinkRegion(

-    Region r,

-    int dx, int dy)

-{

-    Region s, t;

-    int grow;

-

-    if (!dx && !dy) return 0;

-    if (! (s = XCreateRegion()) )

-	return 0;

-    if (! (t = XCreateRegion()) ) {

-	XDestroyRegion(s);

-	return 0;

-    }

-    if ((grow = (dx < 0))) dx = -dx;

-    if (dx) Compress(r, s, t, (unsigned) 2*dx, TRUE, grow);

-    if ((grow = (dy < 0))) dy = -dy;

-    if (dy) Compress(r, s, t, (unsigned) 2*dy, FALSE, grow);

-    XOffsetRegion(r, dx, dy);

-    XDestroyRegion(s);

-    XDestroyRegion(t);

-    return 0;

-}

-

-

-/*======================================================================

- *	    Region Intersection

- *====================================================================*/

-/*-

- *-----------------------------------------------------------------------

- * miIntersectO --

- *	Handle an overlapping band for miIntersect.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	Rectangles may be added to the region.

- *

- *-----------------------------------------------------------------------

- */

-/* static void*/

-static int

-miIntersectO (

-    register Region	pReg,

-    register BoxPtr	r1,

-    BoxPtr  	  	r1End,

-    register BoxPtr	r2,

-    BoxPtr  	  	r2End,

-    short    	  	y1,

-    short    	  	y2)

-{

-    register short  	x1;

-    register short  	x2;

-    register BoxPtr	pNextRect;

-

-    pNextRect = &pReg->rects[pReg->numRects];

-

-    while ((r1 != r1End) && (r2 != r2End))

-    {

-	x1 = max(r1->x1,r2->x1);

-	x2 = min(r1->x2,r2->x2);

-

-	/*

-	 * If there's any overlap between the two rectangles, add that

-	 * overlap to the new region.

-	 * There's no need to check for subsumption because the only way

-	 * such a need could arise is if some region has two rectangles

-	 * right next to each other. Since that should never happen...

-	 */

-	if (x1 < x2)

-	{

-	    assert(y1<y2);

-

-	    MEMCHECK(pReg, pNextRect, pReg->rects);

-	    pNextRect->x1 = x1;

-	    pNextRect->y1 = y1;

-	    pNextRect->x2 = x2;

-	    pNextRect->y2 = y2;

-	    pReg->numRects += 1;

-	    pNextRect++;

-	    assert(pReg->numRects <= pReg->size);

-	}

-

-	/*

-	 * Need to advance the pointers. Shift the one that extends

-	 * to the right the least, since the other still has a chance to

-	 * overlap with that region's next rectangle, if you see what I mean.

-	 */

-	if (r1->x2 < r2->x2)

-	{

-	    r1++;

-	}

-	else if (r2->x2 < r1->x2)

-	{

-	    r2++;

-	}

-	else

-	{

-	    r1++;

-	    r2++;

-	}

-    }

-    return 0;	/* lint */

-}

-

-int

-XIntersectRegion(

-    Region 	  	reg1,

-    Region	  	reg2,          /* source regions     */

-    register Region 	newReg)               /* destination Region */

-{

-   /* check for trivial reject */

-    if ( (!(reg1->numRects)) || (!(reg2->numRects))  ||

-	(!EXTENTCHECK(&reg1->extents, &reg2->extents)))

-        newReg->numRects = 0;

-    else

-	miRegionOp (newReg, reg1, reg2,

-    		miIntersectO, NULL, NULL);

-

-    /*

-     * Can't alter newReg's extents before we call miRegionOp because

-     * it might be one of the source regions and miRegionOp depends

-     * on the extents of those regions being the same. Besides, this

-     * way there's no checking against rectangles that will be nuked

-     * due to coalescing, so we have to examine fewer rectangles.

-     */

-    miSetExtents(newReg);

-    return 1;

-}

-

-static void

-miRegionCopy(

-    register Region dstrgn,

-    register Region rgn)

-

-{

-    if (dstrgn != rgn) /*  don't want to copy to itself */

-    {

-        if (dstrgn->size < rgn->numRects)

-        {

-            if (dstrgn->rects)

-            {

-		BOX *prevRects = dstrgn->rects;

-

-                if (! (dstrgn->rects = (BOX *)

-		       Xrealloc((char *) dstrgn->rects,

-				(unsigned) rgn->numRects * (sizeof(BOX))))) {

-		    Xfree(prevRects);

-		    return;

-		}

-            }

-            dstrgn->size = rgn->numRects;

-	}

-        dstrgn->numRects = rgn->numRects;

-        dstrgn->extents.x1 = rgn->extents.x1;

-        dstrgn->extents.y1 = rgn->extents.y1;

-        dstrgn->extents.x2 = rgn->extents.x2;

-        dstrgn->extents.y2 = rgn->extents.y2;

-

-	memcpy((char *) dstrgn->rects, (char *) rgn->rects,

-	       (int) (rgn->numRects * sizeof(BOX)));

-    }

-}

-

-/*======================================================================

- *	    Generic Region Operator

- *====================================================================*/

-

-/*-

- *-----------------------------------------------------------------------

- * miCoalesce --

- *	Attempt to merge the boxes in the current band with those in the

- *	previous one. Used only by miRegionOp.

- *

- * Results:

- *	The new index for the previous band.

- *

- * Side Effects:

- *	If coalescing takes place:

- *	    - rectangles in the previous band will have their y2 fields

- *	      altered.

- *	    - pReg->numRects will be decreased.

- *

- *-----------------------------------------------------------------------

- */

-/* static int*/

-static int

-miCoalesce(

-    register Region	pReg,	    	/* Region to coalesce */

-    int	    	  	prevStart,  	/* Index of start of previous band */

-    int	    	  	curStart)   	/* Index of start of current band */

-{

-    register BoxPtr	pPrevBox;   	/* Current box in previous band */

-    register BoxPtr	pCurBox;    	/* Current box in current band */

-    register BoxPtr	pRegEnd;    	/* End of region */

-    int	    	  	curNumRects;	/* Number of rectangles in current

-					 * band */

-    int	    	  	prevNumRects;	/* Number of rectangles in previous

-					 * band */

-    int	    	  	bandY1;	    	/* Y1 coordinate for current band */

-

-    pRegEnd = &pReg->rects[pReg->numRects];

-

-    pPrevBox = &pReg->rects[prevStart];

-    prevNumRects = curStart - prevStart;

-

-    /*

-     * Figure out how many rectangles are in the current band. Have to do

-     * this because multiple bands could have been added in miRegionOp

-     * at the end when one region has been exhausted.

-     */

-    pCurBox = &pReg->rects[curStart];

-    bandY1 = pCurBox->y1;

-    for (curNumRects = 0;

-	 (pCurBox != pRegEnd) && (pCurBox->y1 == bandY1);

-	 curNumRects++)

-    {

-	pCurBox++;

-    }

-

-    if (pCurBox != pRegEnd)

-    {

-	/*

-	 * If more than one band was added, we have to find the start

-	 * of the last band added so the next coalescing job can start

-	 * at the right place... (given when multiple bands are added,

-	 * this may be pointless -- see above).

-	 */

-	pRegEnd--;

-	while (pRegEnd[-1].y1 == pRegEnd->y1)

-	{

-	    pRegEnd--;

-	}

-	curStart = pRegEnd - pReg->rects;

-	pRegEnd = pReg->rects + pReg->numRects;

-    }

-

-    if ((curNumRects == prevNumRects) && (curNumRects != 0)) {

-	pCurBox -= curNumRects;

-	/*

-	 * The bands may only be coalesced if the bottom of the previous

-	 * matches the top scanline of the current.

-	 */

-	if (pPrevBox->y2 == pCurBox->y1)

-	{

-	    /*

-	     * Make sure the bands have boxes in the same places. This

-	     * assumes that boxes have been added in such a way that they

-	     * cover the most area possible. I.e. two boxes in a band must

-	     * have some horizontal space between them.

-	     */

-	    do

-	    {

-		if ((pPrevBox->x1 != pCurBox->x1) ||

-		    (pPrevBox->x2 != pCurBox->x2))

-		{

-		    /*

-		     * The bands don't line up so they can't be coalesced.

-		     */

-		    return (curStart);

-		}

-		pPrevBox++;

-		pCurBox++;

-		prevNumRects -= 1;

-	    } while (prevNumRects != 0);

-

-	    pReg->numRects -= curNumRects;

-	    pCurBox -= curNumRects;

-	    pPrevBox -= curNumRects;

-

-	    /*

-	     * The bands may be merged, so set the bottom y of each box

-	     * in the previous band to that of the corresponding box in

-	     * the current band.

-	     */

-	    do

-	    {

-		pPrevBox->y2 = pCurBox->y2;

-		pPrevBox++;

-		pCurBox++;

-		curNumRects -= 1;

-	    } while (curNumRects != 0);

-

-	    /*

-	     * If only one band was added to the region, we have to backup

-	     * curStart to the start of the previous band.

-	     *

-	     * If more than one band was added to the region, copy the

-	     * other bands down. The assumption here is that the other bands

-	     * came from the same region as the current one and no further

-	     * coalescing can be done on them since it's all been done

-	     * already... curStart is already in the right place.

-	     */

-	    if (pCurBox == pRegEnd)

-	    {

-		curStart = prevStart;

-	    }

-	    else

-	    {

-		do

-		{

-		    *pPrevBox++ = *pCurBox++;

-		} while (pCurBox != pRegEnd);

-	    }

-

-	}

-    }

-    return (curStart);

-}

-

-/*-

- *-----------------------------------------------------------------------

- * miRegionOp --

- *	Apply an operation to two regions. Called by miUnion, miInverse,

- *	miSubtract, miIntersect...

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	The new region is overwritten.

- *

- * Notes:

- *	The idea behind this function is to view the two regions as sets.

- *	Together they cover a rectangle of area that this function divides

- *	into horizontal bands where points are covered only by one region

- *	or by both. For the first case, the nonOverlapFunc is called with

- *	each the band and the band's upper and lower extents. For the

- *	second, the overlapFunc is called to process the entire band. It

- *	is responsible for clipping the rectangles in the band, though

- *	this function provides the boundaries.

- *	At the end of each band, the new region is coalesced, if possible,

- *	to reduce the number of rectangles in the region.

- *

- *-----------------------------------------------------------------------

- */

-/* static void*/

-static void

-miRegionOp(

-    register Region 	newReg,	    	    	/* Place to store result */

-    Region	  	reg1,	    	    	/* First region in operation */

-    Region	  	reg2,	    	    	/* 2d region in operation */

-    int    	  	(*overlapFunc)(

-        register Region     pReg,

-        register BoxPtr     r1,

-        BoxPtr              r1End,

-        register BoxPtr     r2,

-        BoxPtr              r2End,

-        short               y1,

-        short               y2),                /* Function to call for over-

-						 * lapping bands */

-    int    	  	(*nonOverlap1Func)(

-        register Region     pReg,

-        register BoxPtr     r,

-        BoxPtr              rEnd,

-        register short      y1,

-        register short      y2),                /* Function to call for non-

-						 * overlapping bands in region

-						 * 1 */

-    int    	  	(*nonOverlap2Func)(

-        register Region     pReg,

-        register BoxPtr     r,

-        BoxPtr              rEnd,

-        register short      y1,

-        register short      y2))                /* Function to call for non-

-						 * overlapping bands in region

-						 * 2 */

-{

-    register BoxPtr	r1; 	    	    	/* Pointer into first region */

-    register BoxPtr	r2; 	    	    	/* Pointer into 2d region */

-    BoxPtr  	  	r1End;	    	    	/* End of 1st region */

-    BoxPtr  	  	r2End;	    	    	/* End of 2d region */

-    register short  	ybot;	    	    	/* Bottom of intersection */

-    register short  	ytop;	    	    	/* Top of intersection */

-    BoxPtr  	  	oldRects;   	    	/* Old rects for newReg */

-    int	    	  	prevBand;   	    	/* Index of start of

-						 * previous band in newReg */

-    int	    	  	curBand;    	    	/* Index of start of current

-						 * band in newReg */

-    register BoxPtr 	r1BandEnd;  	    	/* End of current band in r1 */

-    register BoxPtr 	r2BandEnd;  	    	/* End of current band in r2 */

-    short     	  	top;	    	    	/* Top of non-overlapping

-						 * band */

-    short     	  	bot;	    	    	/* Bottom of non-overlapping

-						 * band */

-

-    /*

-     * Initialization:

-     *	set r1, r2, r1End and r2End appropriately, preserve the important

-     * parts of the destination region until the end in case it's one of

-     * the two source regions, then mark the "new" region empty, allocating

-     * another array of rectangles for it to use.

-     */

-    r1 = reg1->rects;

-    r2 = reg2->rects;

-    r1End = r1 + reg1->numRects;

-    r2End = r2 + reg2->numRects;

-

-    oldRects = newReg->rects;

-

-    EMPTY_REGION(newReg);

-

-    /*

-     * Allocate a reasonable number of rectangles for the new region. The idea

-     * is to allocate enough so the individual functions don't need to

-     * reallocate and copy the array, which is time consuming, yet we don't

-     * have to worry about using too much memory. I hope to be able to

-     * nuke the Xrealloc() at the end of this function eventually.

-     */

-    newReg->size = max(reg1->numRects,reg2->numRects) * 2;

-

-    if (! (newReg->rects = (BoxPtr)

-	   Xmalloc ((unsigned) (sizeof(BoxRec) * newReg->size)))) {

-	newReg->size = 0;

-	return;

-    }

-

-    /*

-     * Initialize ybot and ytop.

-     * In the upcoming loop, ybot and ytop serve different functions depending

-     * on whether the band being handled is an overlapping or non-overlapping

-     * band.

-     * 	In the case of a non-overlapping band (only one of the regions

-     * has points in the band), ybot is the bottom of the most recent

-     * intersection and thus clips the top of the rectangles in that band.

-     * ytop is the top of the next intersection between the two regions and

-     * serves to clip the bottom of the rectangles in the current band.

-     *	For an overlapping band (where the two regions intersect), ytop clips

-     * the top of the rectangles of both regions and ybot clips the bottoms.

-     */

-    if (reg1->extents.y1 < reg2->extents.y1)

-	ybot = reg1->extents.y1;

-    else

-	ybot = reg2->extents.y1;

-

-    /*

-     * prevBand serves to mark the start of the previous band so rectangles

-     * can be coalesced into larger rectangles. qv. miCoalesce, above.

-     * In the beginning, there is no previous band, so prevBand == curBand

-     * (curBand is set later on, of course, but the first band will always

-     * start at index 0). prevBand and curBand must be indices because of

-     * the possible expansion, and resultant moving, of the new region's

-     * array of rectangles.

-     */

-    prevBand = 0;

-

-    do

-    {

-	curBand = newReg->numRects;

-

-	/*

-	 * This algorithm proceeds one source-band (as opposed to a

-	 * destination band, which is determined by where the two regions

-	 * intersect) at a time. r1BandEnd and r2BandEnd serve to mark the

-	 * rectangle after the last one in the current band for their

-	 * respective regions.

-	 */

-	r1BandEnd = r1;

-	while ((r1BandEnd != r1End) && (r1BandEnd->y1 == r1->y1))

-	{

-	    r1BandEnd++;

-	}

-

-	r2BandEnd = r2;

-	while ((r2BandEnd != r2End) && (r2BandEnd->y1 == r2->y1))

-	{

-	    r2BandEnd++;

-	}

-

-	/*

-	 * First handle the band that doesn't intersect, if any.

-	 *

-	 * Note that attention is restricted to one band in the

-	 * non-intersecting region at once, so if a region has n

-	 * bands between the current position and the next place it overlaps

-	 * the other, this entire loop will be passed through n times.

-	 */

-	if (r1->y1 < r2->y1)

-	{

-	    top = max(r1->y1,ybot);

-	    bot = min(r1->y2,r2->y1);

-

-	    if ((top != bot) && (nonOverlap1Func != NULL))

-	    {

-		(* nonOverlap1Func) (newReg, r1, r1BandEnd, top, bot);

-	    }

-

-	    ytop = r2->y1;

-	}

-	else if (r2->y1 < r1->y1)

-	{

-	    top = max(r2->y1,ybot);

-	    bot = min(r2->y2,r1->y1);

-

-	    if ((top != bot) && (nonOverlap2Func != NULL))

-	    {

-		(* nonOverlap2Func) (newReg, r2, r2BandEnd, top, bot);

-	    }

-

-	    ytop = r1->y1;

-	}

-	else

-	{

-	    ytop = r1->y1;

-	}

-

-	/*

-	 * If any rectangles got added to the region, try and coalesce them

-	 * with rectangles from the previous band. Note we could just do

-	 * this test in miCoalesce, but some machines incur a not

-	 * inconsiderable cost for function calls, so...

-	 */

-	if (newReg->numRects != curBand)

-	{

-	    prevBand = miCoalesce (newReg, prevBand, curBand);

-	}

-

-	/*

-	 * Now see if we've hit an intersecting band. The two bands only

-	 * intersect if ybot > ytop

-	 */

-	ybot = min(r1->y2, r2->y2);

-	curBand = newReg->numRects;

-	if (ybot > ytop)

-	{

-	    (* overlapFunc) (newReg, r1, r1BandEnd, r2, r2BandEnd, ytop, ybot);

-

-	}

-

-	if (newReg->numRects != curBand)

-	{

-	    prevBand = miCoalesce (newReg, prevBand, curBand);

-	}

-

-	/*

-	 * If we've finished with a band (y2 == ybot) we skip forward

-	 * in the region to the next band.

-	 */

-	if (r1->y2 == ybot)

-	{

-	    r1 = r1BandEnd;

-	}

-	if (r2->y2 == ybot)

-	{

-	    r2 = r2BandEnd;

-	}

-    } while ((r1 != r1End) && (r2 != r2End));

-

-    /*

-     * Deal with whichever region still has rectangles left.

-     */

-    curBand = newReg->numRects;

-    if (r1 != r1End)

-    {

-	if (nonOverlap1Func != NULL)

-	{

-	    do

-	    {

-		r1BandEnd = r1;

-		while ((r1BandEnd < r1End) && (r1BandEnd->y1 == r1->y1))

-		{

-		    r1BandEnd++;

-		}

-		(* nonOverlap1Func) (newReg, r1, r1BandEnd,

-				     max(r1->y1,ybot), r1->y2);

-		r1 = r1BandEnd;

-	    } while (r1 != r1End);

-	}

-    }

-    else if ((r2 != r2End) && (nonOverlap2Func != NULL))

-    {

-	do

-	{

-	    r2BandEnd = r2;

-	    while ((r2BandEnd < r2End) && (r2BandEnd->y1 == r2->y1))

-	    {

-		 r2BandEnd++;

-	    }

-	    (* nonOverlap2Func) (newReg, r2, r2BandEnd,

-				max(r2->y1,ybot), r2->y2);

-	    r2 = r2BandEnd;

-	} while (r2 != r2End);

-    }

-

-    if (newReg->numRects != curBand)

-    {

-	(void) miCoalesce (newReg, prevBand, curBand);

-    }

-

-    /*

-     * A bit of cleanup. To keep regions from growing without bound,

-     * we shrink the array of rectangles to match the new number of

-     * rectangles in the region. This never goes to 0, however...

-     *

-     * Only do this stuff if the number of rectangles allocated is more than

-     * twice the number of rectangles in the region (a simple optimization...).

-     */

-    if (newReg->numRects < (newReg->size >> 1))

-    {

-	if (REGION_NOT_EMPTY(newReg))

-	{

-	    BoxPtr prev_rects = newReg->rects;

-	    newReg->size = newReg->numRects;

-	    newReg->rects = (BoxPtr) Xrealloc ((char *) newReg->rects,

-				   (unsigned) (sizeof(BoxRec) * newReg->size));

-	    if (! newReg->rects)

-		newReg->rects = prev_rects;

-	}

-	else

-	{

-	    /*

-	     * No point in doing the extra work involved in an Xrealloc if

-	     * the region is empty

-	     */

-	    newReg->size = 1;

-	    Xfree((char *) newReg->rects);

-	    newReg->rects = (BoxPtr) Xmalloc(sizeof(BoxRec));

-	}

-    }

-    Xfree ((char *) oldRects);

-    return;

-}

-

-

-/*======================================================================

- *	    Region Union

- *====================================================================*/

-

-/*-

- *-----------------------------------------------------------------------

- * miUnionNonO --

- *	Handle a non-overlapping band for the union operation. Just

- *	Adds the rectangles into the region. Doesn't have to check for

- *	subsumption or anything.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	pReg->numRects is incremented and the final rectangles overwritten

- *	with the rectangles we're passed.

- *

- *-----------------------------------------------------------------------

- */

-/* static void*/

-static int

-miUnionNonO (

-    register Region	pReg,

-    register BoxPtr	r,

-    BoxPtr  	  	rEnd,

-    register short  	y1,

-    register short  	y2)

-{

-    register BoxPtr	pNextRect;

-

-    pNextRect = &pReg->rects[pReg->numRects];

-

-    assert(y1 < y2);

-

-    while (r != rEnd)

-    {

-	assert(r->x1 < r->x2);

-	MEMCHECK(pReg, pNextRect, pReg->rects);

-	pNextRect->x1 = r->x1;

-	pNextRect->y1 = y1;

-	pNextRect->x2 = r->x2;

-	pNextRect->y2 = y2;

-	pReg->numRects += 1;

-	pNextRect++;

-

-	assert(pReg->numRects<=pReg->size);

-	r++;

-    }

-    return 0;	/* lint */

-}

-

-

-/*-

- *-----------------------------------------------------------------------

- * miUnionO --

- *	Handle an overlapping band for the union operation. Picks the

- *	left-most rectangle each time and merges it into the region.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	Rectangles are overwritten in pReg->rects and pReg->numRects will

- *	be changed.

- *

- *-----------------------------------------------------------------------

- */

-

-/* static void*/

-static int

-miUnionO (

-    register Region	pReg,

-    register BoxPtr	r1,

-    BoxPtr  	  	r1End,

-    register BoxPtr	r2,

-    BoxPtr  	  	r2End,

-    register short	y1,

-    register short	y2)

-{

-    register BoxPtr	pNextRect;

-

-    pNextRect = &pReg->rects[pReg->numRects];

-

-#define MERGERECT(r) \

-    if ((pReg->numRects != 0) &&  \

-	(pNextRect[-1].y1 == y1) &&  \

-	(pNextRect[-1].y2 == y2) &&  \

-	(pNextRect[-1].x2 >= r->x1))  \

-    {  \

-	if (pNextRect[-1].x2 < r->x2)  \

-	{  \

-	    pNextRect[-1].x2 = r->x2;  \

-	    assert(pNextRect[-1].x1<pNextRect[-1].x2); \

-	}  \

-    }  \

-    else  \

-    {  \

-	MEMCHECK(pReg, pNextRect, pReg->rects);  \

-	pNextRect->y1 = y1;  \

-	pNextRect->y2 = y2;  \

-	pNextRect->x1 = r->x1;  \

-	pNextRect->x2 = r->x2;  \

-	pReg->numRects += 1;  \

-        pNextRect += 1;  \

-    }  \

-    assert(pReg->numRects<=pReg->size);\

-    r++;

-

-    assert (y1<y2);

-    while ((r1 != r1End) && (r2 != r2End))

-    {

-	if (r1->x1 < r2->x1)

-	{

-	    MERGERECT(r1);

-	}

-	else

-	{

-	    MERGERECT(r2);

-	}

-    }

-

-    if (r1 != r1End)

-    {

-	do

-	{

-	    MERGERECT(r1);

-	} while (r1 != r1End);

-    }

-    else while (r2 != r2End)

-    {

-	MERGERECT(r2);

-    }

-    return 0;	/* lint */

-}

-

-int

-XUnionRegion(

-    Region 	  reg1,

-    Region	  reg2,             /* source regions     */

-    Region 	  newReg)                  /* destination Region */

-{

-    /*  checks all the simple cases */

-

-    /*

-     * Region 1 and 2 are the same or region 1 is empty

-     */

-    if ( (reg1 == reg2) || (!(reg1->numRects)) )

-    {

-        if (newReg != reg2)

-            miRegionCopy(newReg, reg2);

-        return 1;

-    }

-

-    /*

-     * if nothing to union (region 2 empty)

-     */

-    if (!(reg2->numRects))

-    {

-        if (newReg != reg1)

-            miRegionCopy(newReg, reg1);

-        return 1;

-    }

-

-    /*

-     * Region 1 completely subsumes region 2

-     */

-    if ((reg1->numRects == 1) &&

-	(reg1->extents.x1 <= reg2->extents.x1) &&

-	(reg1->extents.y1 <= reg2->extents.y1) &&

-	(reg1->extents.x2 >= reg2->extents.x2) &&

-	(reg1->extents.y2 >= reg2->extents.y2))

-    {

-        if (newReg != reg1)

-            miRegionCopy(newReg, reg1);

-        return 1;

-    }

-

-    /*

-     * Region 2 completely subsumes region 1

-     */

-    if ((reg2->numRects == 1) &&

-	(reg2->extents.x1 <= reg1->extents.x1) &&

-	(reg2->extents.y1 <= reg1->extents.y1) &&

-	(reg2->extents.x2 >= reg1->extents.x2) &&

-	(reg2->extents.y2 >= reg1->extents.y2))

-    {

-        if (newReg != reg2)

-            miRegionCopy(newReg, reg2);

-        return 1;

-    }

-

-    miRegionOp (newReg, reg1, reg2, miUnionO,

-    		miUnionNonO, miUnionNonO);

-

-    newReg->extents.x1 = min(reg1->extents.x1, reg2->extents.x1);

-    newReg->extents.y1 = min(reg1->extents.y1, reg2->extents.y1);

-    newReg->extents.x2 = max(reg1->extents.x2, reg2->extents.x2);

-    newReg->extents.y2 = max(reg1->extents.y2, reg2->extents.y2);

-

-    return 1;

-}

-

-

-/*======================================================================

- * 	    	  Region Subtraction

- *====================================================================*/

-

-/*-

- *-----------------------------------------------------------------------

- * miSubtractNonO --

- *	Deal with non-overlapping band for subtraction. Any parts from

- *	region 2 we discard. Anything from region 1 we add to the region.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	pReg may be affected.

- *

- *-----------------------------------------------------------------------

- */

-/* static void*/

-static int

-miSubtractNonO1 (

-    register Region	pReg,

-    register BoxPtr	r,

-    BoxPtr  	  	rEnd,

-    register short  	y1,

-    register short   	y2)

-{

-    register BoxPtr	pNextRect;

-

-    pNextRect = &pReg->rects[pReg->numRects];

-

-    assert(y1<y2);

-

-    while (r != rEnd)

-    {

-	assert(r->x1<r->x2);

-	MEMCHECK(pReg, pNextRect, pReg->rects);

-	pNextRect->x1 = r->x1;

-	pNextRect->y1 = y1;

-	pNextRect->x2 = r->x2;

-	pNextRect->y2 = y2;

-	pReg->numRects += 1;

-	pNextRect++;

-

-	assert(pReg->numRects <= pReg->size);

-

-	r++;

-    }

-    return 0;	/* lint */

-}

-

-/*-

- *-----------------------------------------------------------------------

- * miSubtractO --

- *	Overlapping band subtraction. x1 is the left-most point not yet

- *	checked.

- *

- * Results:

- *	None.

- *

- * Side Effects:

- *	pReg may have rectangles added to it.

- *

- *-----------------------------------------------------------------------

- */

-/* static void*/

-static int

-miSubtractO (

-    register Region	pReg,

-    register BoxPtr	r1,

-    BoxPtr  	  	r1End,

-    register BoxPtr	r2,

-    BoxPtr  	  	r2End,

-    register short  	y1,

-    register short  	y2)

-{

-    register BoxPtr	pNextRect;

-    register int  	x1;

-

-    x1 = r1->x1;

-

-    assert(y1<y2);

-    pNextRect = &pReg->rects[pReg->numRects];

-

-    while ((r1 != r1End) && (r2 != r2End))

-    {

-	if (r2->x2 <= x1)

-	{

-	    /*

-	     * Subtrahend missed the boat: go to next subtrahend.

-	     */

-	    r2++;

-	}

-	else if (r2->x1 <= x1)

-	{

-	    /*

-	     * Subtrahend preceeds minuend: nuke left edge of minuend.

-	     */

-	    x1 = r2->x2;

-	    if (x1 >= r1->x2)

-	    {

-		/*

-		 * Minuend completely covered: advance to next minuend and

-		 * reset left fence to edge of new minuend.

-		 */

-		r1++;

-		if (r1 != r1End)

-		    x1 = r1->x1;

-	    }

-	    else

-	    {

-		/*

-		 * Subtrahend now used up since it doesn't extend beyond

-		 * minuend

-		 */

-		r2++;

-	    }

-	}

-	else if (r2->x1 < r1->x2)

-	{

-	    /*

-	     * Left part of subtrahend covers part of minuend: add uncovered

-	     * part of minuend to region and skip to next subtrahend.

-	     */

-	    assert(x1<r2->x1);

-	    MEMCHECK(pReg, pNextRect, pReg->rects);

-	    pNextRect->x1 = x1;

-	    pNextRect->y1 = y1;

-	    pNextRect->x2 = r2->x1;

-	    pNextRect->y2 = y2;

-	    pReg->numRects += 1;

-	    pNextRect++;

-

-	    assert(pReg->numRects<=pReg->size);

-

-	    x1 = r2->x2;

-	    if (x1 >= r1->x2)

-	    {

-		/*

-		 * Minuend used up: advance to new...

-		 */

-		r1++;

-		if (r1 != r1End)

-		    x1 = r1->x1;

-	    }

-	    else

-	    {

-		/*

-		 * Subtrahend used up

-		 */

-		r2++;

-	    }

-	}

-	else

-	{

-	    /*

-	     * Minuend used up: add any remaining piece before advancing.

-	     */

-	    if (r1->x2 > x1)

-	    {

-		MEMCHECK(pReg, pNextRect, pReg->rects);

-		pNextRect->x1 = x1;

-		pNextRect->y1 = y1;

-		pNextRect->x2 = r1->x2;

-		pNextRect->y2 = y2;

-		pReg->numRects += 1;

-		pNextRect++;

-		assert(pReg->numRects<=pReg->size);

-	    }

-	    r1++;

-	    if (r1 != r1End)

-		x1 = r1->x1;

-	}

-    }

-

-    /*

-     * Add remaining minuend rectangles to region.

-     */

-    while (r1 != r1End)

-    {

-	assert(x1<r1->x2);

-	MEMCHECK(pReg, pNextRect, pReg->rects);

-	pNextRect->x1 = x1;

-	pNextRect->y1 = y1;

-	pNextRect->x2 = r1->x2;

-	pNextRect->y2 = y2;

-	pReg->numRects += 1;

-	pNextRect++;

-

-	assert(pReg->numRects<=pReg->size);

-

-	r1++;

-	if (r1 != r1End)

-	{

-	    x1 = r1->x1;

-	}

-    }

-    return 0;	/* lint */

-}

-

-/*-

- *-----------------------------------------------------------------------

- * miSubtract --

- *	Subtract regS from regM and leave the result in regD.

- *	S stands for subtrahend, M for minuend and D for difference.

- *

- * Results:

- *	TRUE.

- *

- * Side Effects:

- *	regD is overwritten.

- *

- *-----------------------------------------------------------------------

- */

-

-int

-XSubtractRegion(

-    Region 	  	regM,

-    Region	  	regS,

-    register Region	regD)

-{

-   /* check for trivial reject */

-    if ( (!(regM->numRects)) || (!(regS->numRects))  ||

-	(!EXTENTCHECK(&regM->extents, &regS->extents)) )

-    {

-	miRegionCopy(regD, regM);

-        return 1;

-    }

-

-    miRegionOp (regD, regM, regS, miSubtractO,

-    		miSubtractNonO1, NULL);

-

-    /*

-     * Can't alter newReg's extents before we call miRegionOp because

-     * it might be one of the source regions and miRegionOp depends

-     * on the extents of those regions being the unaltered. Besides, this

-     * way there's no checking against rectangles that will be nuked

-     * due to coalescing, so we have to examine fewer rectangles.

-     */

-    miSetExtents (regD);

-    return 1;

-}

-

-int

-XXorRegion(Region sra, Region srb, Region dr)

-{

-    Region tra, trb;

-

-    if (! (tra = XCreateRegion()) )

-	return 0;

-    if (! (trb = XCreateRegion()) ) {

-	XDestroyRegion(tra);

-	return 0;

-    }

-    (void) XSubtractRegion(sra,srb,tra);

-    (void) XSubtractRegion(srb,sra,trb);

-    (void) XUnionRegion(tra,trb,dr);

-    XDestroyRegion(tra);

-    XDestroyRegion(trb);

-    return 0;

-}

-

-/*

- * Check to see if the region is empty.  Assumes a region is passed

- * as a parameter

- */

-int

-XEmptyRegion(

-    Region r)

-{

-    if( r->numRects == 0 ) return TRUE;

-    else  return FALSE;

-}

-

-/*

- *	Check to see if two regions are equal

- */

-int

-XEqualRegion(Region r1, Region r2)

-{

-    int i;

-

-    if( r1->numRects != r2->numRects ) return FALSE;

-    else if( r1->numRects == 0 ) return TRUE;

-    else if ( r1->extents.x1 != r2->extents.x1 ) return FALSE;

-    else if ( r1->extents.x2 != r2->extents.x2 ) return FALSE;

-    else if ( r1->extents.y1 != r2->extents.y1 ) return FALSE;

-    else if ( r1->extents.y2 != r2->extents.y2 ) return FALSE;

-    else for( i=0; i < r1->numRects; i++ ) {

-    	if ( r1->rects[i].x1 != r2->rects[i].x1 ) return FALSE;

-    	else if ( r1->rects[i].x2 != r2->rects[i].x2 ) return FALSE;

-    	else if ( r1->rects[i].y1 != r2->rects[i].y1 ) return FALSE;

-    	else if ( r1->rects[i].y2 != r2->rects[i].y2 ) return FALSE;

-    }

-    return TRUE;

-}

-

-int

-XPointInRegion(

-    Region pRegion,

-    int x, int y)

-{

-    int i;

-

-    if (pRegion->numRects == 0)

-        return FALSE;

-    if (!INBOX(pRegion->extents, x, y))

-        return FALSE;

-    for (i=0; i<pRegion->numRects; i++)

-    {

-        if (INBOX (pRegion->rects[i], x, y))

-	    return TRUE;

-    }

-    return FALSE;

-}

-

-int

-XRectInRegion(

-    register Region	region,

-    int rx, int ry,

-    unsigned int rwidth, unsigned int rheight)

-{

-    register BoxPtr pbox;

-    register BoxPtr pboxEnd;

-    Box rect;

-    register BoxPtr prect = &rect;

-    int      partIn, partOut;

-

-    prect->x1 = rx;

-    prect->y1 = ry;

-    prect->x2 = rwidth + rx;

-    prect->y2 = rheight + ry;

-

-    /* this is (just) a useful optimization */

-    if ((region->numRects == 0) || !EXTENTCHECK(&region->extents, prect))

-        return(RectangleOut);

-

-    partOut = FALSE;

-    partIn = FALSE;

-

-    /* can stop when both partOut and partIn are TRUE, or we reach prect->y2 */

-    for (pbox = region->rects, pboxEnd = pbox + region->numRects;

-	 pbox < pboxEnd;

-	 pbox++)

-    {

-

-	if (pbox->y2 <= ry)

-	   continue;	/* getting up to speed or skipping remainder of band */

-

-	if (pbox->y1 > ry)

-	{

-	   partOut = TRUE;	/* missed part of rectangle above */

-	   if (partIn || (pbox->y1 >= prect->y2))

-	      break;

-	   ry = pbox->y1;	/* x guaranteed to be == prect->x1 */

-	}

-

-	if (pbox->x2 <= rx)

-	   continue;		/* not far enough over yet */

-

-	if (pbox->x1 > rx)

-	{

-	   partOut = TRUE;	/* missed part of rectangle to left */

-	   if (partIn)

-	      break;

-	}

-

-	if (pbox->x1 < prect->x2)

-	{

-	    partIn = TRUE;	/* definitely overlap */

-	    if (partOut)

-	       break;

-	}

-

-	if (pbox->x2 >= prect->x2)

-	{

-	   ry = pbox->y2;	/* finished with this band */

-	   if (ry >= prect->y2)

-	      break;

-	   rx = prect->x1;	/* reset x out to left again */

-	} else

-	{

-	    /*

-	     * Because boxes in a band are maximal width, if the first box

-	     * to overlap the rectangle doesn't completely cover it in that

-	     * band, the rectangle must be partially out, since some of it

-	     * will be uncovered in that band. partIn will have been set true

-	     * by now...

-	     */

-	    break;

-	}

-

-    }

-

-    return(partIn ? ((ry < prect->y2) ? RectanglePart : RectangleIn) :

-		RectangleOut);

-}

+/************************************************************************
+
+Copyright 1987, 1988, 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, 1988 by Digital Equipment Corporation, Maynard, Massachusetts.
+
+                        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 of Digital not be
+used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission.
+
+DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
+DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
+ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+SOFTWARE.
+
+************************************************************************/
+/*
+ * The functions in this file implement the Region abstraction, similar to one
+ * used in the X11 sample server. A Region is simply an area, as the name
+ * implies, and is implemented as a "y-x-banded" array of rectangles. To
+ * explain: Each Region is made up of a certain number of rectangles sorted
+ * by y coordinate first, and then by x coordinate.
+ *
+ * Furthermore, the rectangles are banded such that every rectangle with a
+ * given upper-left y coordinate (y1) will have the same lower-right y
+ * coordinate (y2) and vice versa. If a rectangle has scanlines in a band, it
+ * will span the entire vertical distance of the band. This means that some
+ * areas that could be merged into a taller rectangle will be represented as
+ * several shorter rectangles to account for shorter rectangles to its left
+ * or right but within its "vertical scope".
+ *
+ * An added constraint on the rectangles is that they must cover as much
+ * horizontal area as possible. E.g. no two rectangles in a band are allowed
+ * to touch.
+ *
+ * Whenever possible, bands will be merged together to cover a greater vertical
+ * distance (and thus reduce the number of rectangles). Two bands can be merged
+ * only if the bottom of one touches the top of the other and they have
+ * rectangles in the same places (of the same width, of course). This maintains
+ * the y-x-banding that's so nice to have...
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include "Xlibint.h"
+#include "Xutil.h"
+#include <X11/Xregion.h>
+#include "poly.h"
+
+#ifdef DEBUG
+#include <stdio.h>
+#define assert(expr) {if (!(expr)) fprintf(stderr,\
+"Assertion failed file %s, line %d: expr\n", __FILE__, __LINE__); }
+#else
+#define assert(expr)
+#endif
+
+typedef int (*overlapProcp)(
+        register Region     pReg,
+        register BoxPtr     r1,
+        BoxPtr              r1End,
+        register BoxPtr     r2,
+        BoxPtr              r2End,
+        short               y1,
+        short               y2);
+
+typedef int (*nonOverlapProcp)(
+    register Region     pReg,
+    register BoxPtr     r,
+    BoxPtr              rEnd,
+    register short      y1,
+    register short      y2);
+
+static void miRegionOp(
+    register Region 	newReg,	    	    	/* Place to store result */
+    Region	  	reg1,	    	    	/* First region in operation */
+    Region	  	reg2,	    	    	/* 2d region in operation */
+    int    	  	(*overlapFunc)(
+        register Region     pReg,
+        register BoxPtr     r1,
+        BoxPtr              r1End,
+        register BoxPtr     r2,
+        BoxPtr              r2End,
+        short               y1,
+        short               y2),                /* Function to call for over-
+						 * lapping bands */
+    int    	  	(*nonOverlap1Func)(
+        register Region     pReg,
+        register BoxPtr     r,
+        BoxPtr              rEnd,
+        register short      y1,
+        register short      y2),                /* Function to call for non-
+						 * overlapping bands in region
+						 * 1 */
+    int    	  	(*nonOverlap2Func)(
+        register Region     pReg,
+        register BoxPtr     r,
+        BoxPtr              rEnd,
+        register short      y1,
+        register short      y2));               /* Function to call for non-
+						 * overlapping bands in region
+						 * 2 */
+
+
+/*	Create a new empty region	*/
+Region
+XCreateRegion(void)
+{
+    Region temp;
+
+    if (! (temp = ( Region )Xmalloc( (unsigned) sizeof( REGION ))))
+	return (Region) NULL;
+    if (! (temp->rects = ( BOX * )Xmalloc( (unsigned) sizeof( BOX )))) {
+	Xfree((char *) temp);
+	return (Region) NULL;
+    }
+    temp->numRects = 0;
+    temp->extents.x1 = 0;
+    temp->extents.y1 = 0;
+    temp->extents.x2 = 0;
+    temp->extents.y2 = 0;
+    temp->size = 1;
+    return( temp );
+}
+
+int
+XClipBox(
+    Region r,
+    XRectangle *rect)
+{
+    rect->x = r->extents.x1;
+    rect->y = r->extents.y1;
+    rect->width = r->extents.x2 - r->extents.x1;
+    rect->height = r->extents.y2 - r->extents.y1;
+    return 1;
+}
+
+int
+XUnionRectWithRegion(
+    register XRectangle *rect,
+    Region source, Region dest)
+{
+    REGION region;
+
+    if (!rect->width || !rect->height)
+	return 0;
+    region.rects = &region.extents;
+    region.numRects = 1;
+    region.extents.x1 = rect->x;
+    region.extents.y1 = rect->y;
+    region.extents.x2 = rect->x + rect->width;
+    region.extents.y2 = rect->y + rect->height;
+    region.size = 1;
+
+    return XUnionRegion(&region, source, dest);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miSetExtents --
+ *	Reset the extents of a region to what they should be. Called by
+ *	miSubtract and miIntersect b/c they can't figure it out along the
+ *	way or do so easily, as miUnion can.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	The region's 'extents' structure is overwritten.
+ *
+ *-----------------------------------------------------------------------
+ */
+static void
+miSetExtents (
+    Region	  	pReg)
+{
+    register BoxPtr	pBox,
+			pBoxEnd,
+			pExtents;
+
+    if (pReg->numRects == 0)
+    {
+	pReg->extents.x1 = 0;
+	pReg->extents.y1 = 0;
+	pReg->extents.x2 = 0;
+	pReg->extents.y2 = 0;
+	return;
+    }
+
+    pExtents = &pReg->extents;
+    pBox = pReg->rects;
+    pBoxEnd = &pBox[pReg->numRects - 1];
+
+    /*
+     * Since pBox is the first rectangle in the region, it must have the
+     * smallest y1 and since pBoxEnd is the last rectangle in the region,
+     * it must have the largest y2, because of banding. Initialize x1 and
+     * x2 from  pBox and pBoxEnd, resp., as good things to initialize them
+     * to...
+     */
+    pExtents->x1 = pBox->x1;
+    pExtents->y1 = pBox->y1;
+    pExtents->x2 = pBoxEnd->x2;
+    pExtents->y2 = pBoxEnd->y2;
+
+    assert(pExtents->y1 < pExtents->y2);
+    while (pBox <= pBoxEnd)
+    {
+	if (pBox->x1 < pExtents->x1)
+	{
+	    pExtents->x1 = pBox->x1;
+	}
+	if (pBox->x2 > pExtents->x2)
+	{
+	    pExtents->x2 = pBox->x2;
+	}
+	pBox++;
+    }
+    assert(pExtents->x1 < pExtents->x2);
+}
+
+int
+XSetRegion(
+    Display *dpy,
+    GC gc,
+    register Region r)
+{
+    register int i;
+    register XRectangle *xr, *pr;
+    register BOX *pb;
+    unsigned long total;
+
+    LockDisplay (dpy);
+    total = r->numRects * sizeof (XRectangle);
+    if ((xr = (XRectangle *) _XAllocTemp(dpy, total))) {
+	for (pr = xr, pb = r->rects, i = r->numRects; --i >= 0; pr++, pb++) {
+	    pr->x = pb->x1;
+	    pr->y = pb->y1;
+	    pr->width = pb->x2 - pb->x1;
+	    pr->height = pb->y2 - pb->y1;
+	}
+    }
+    if (xr || !r->numRects)
+	_XSetClipRectangles(dpy, gc, 0, 0, xr, r->numRects, YXBanded);
+    if (xr)
+	_XFreeTemp(dpy, (char *)xr, total);
+    UnlockDisplay(dpy);
+    SyncHandle();
+    return 1;
+}
+
+int
+XDestroyRegion(
+    Region r)
+{
+    Xfree( (char *) r->rects );
+    Xfree( (char *) r );
+    return 1;
+}
+
+
+/* TranslateRegion(pRegion, x, y)
+   translates in place
+   added by raymond
+*/
+
+int
+XOffsetRegion(
+    register Region pRegion,
+    register int x,
+    register int y)
+{
+    register int nbox;
+    register BOX *pbox;
+
+    pbox = pRegion->rects;
+    nbox = pRegion->numRects;
+
+    while(nbox--)
+    {
+	pbox->x1 += x;
+	pbox->x2 += x;
+	pbox->y1 += y;
+	pbox->y2 += y;
+	pbox++;
+    }
+    pRegion->extents.x1 += x;
+    pRegion->extents.x2 += x;
+    pRegion->extents.y1 += y;
+    pRegion->extents.y2 += y;
+    return 1;
+}
+
+/*
+   Utility procedure Compress:
+   Replace r by the region r', where
+     p in r' iff (Quantifer m <= dx) (p + m in r), and
+     Quantifier is Exists if grow is TRUE, For all if grow is FALSE, and
+     (x,y) + m = (x+m,y) if xdir is TRUE; (x,y+m) if xdir is FALSE.
+
+   Thus, if xdir is TRUE and grow is FALSE, r is replaced by the region
+   of all points p such that p and the next dx points on the same
+   horizontal scan line are all in r.  We do this using by noting
+   that p is the head of a run of length 2^i + k iff p is the head
+   of a run of length 2^i and p+2^i is the head of a run of length
+   k. Thus, the loop invariant: s contains the region corresponding
+   to the runs of length shift.  r contains the region corresponding
+   to the runs of length 1 + dxo & (shift-1), where dxo is the original
+   value of dx.  dx = dxo & ~(shift-1).  As parameters, s and t are
+   scratch regions, so that we don't have to allocate them on every
+   call.
+*/
+
+#define ZOpRegion(a,b,c) if (grow) XUnionRegion(a,b,c); \
+			 else XIntersectRegion(a,b,c)
+#define ZShiftRegion(a,b) if (xdir) XOffsetRegion(a,b,0); \
+			  else XOffsetRegion(a,0,b)
+#define ZCopyRegion(a,b) XUnionRegion(a,a,b)
+
+static void
+Compress(
+    Region r, Region s, Region t,
+    register unsigned dx,
+    register int xdir, register int grow)
+{
+    register unsigned shift = 1;
+
+    ZCopyRegion(r, s);
+    while (dx) {
+        if (dx & shift) {
+            ZShiftRegion(r, -(int)shift);
+            ZOpRegion(r, s, r);
+            dx -= shift;
+            if (!dx) break;
+        }
+        ZCopyRegion(s, t);
+        ZShiftRegion(s, -(int)shift);
+        ZOpRegion(s, t, s);
+        shift <<= 1;
+    }
+}
+
+#undef ZOpRegion
+#undef ZShiftRegion
+#undef ZCopyRegion
+
+int
+XShrinkRegion(
+    Region r,
+    int dx, int dy)
+{
+    Region s, t;
+    int grow;
+
+    if (!dx && !dy) return 0;
+    if (! (s = XCreateRegion()) )
+	return 0;
+    if (! (t = XCreateRegion()) ) {
+	XDestroyRegion(s);
+	return 0;
+    }
+    if ((grow = (dx < 0))) dx = -dx;
+    if (dx) Compress(r, s, t, (unsigned) 2*dx, TRUE, grow);
+    if ((grow = (dy < 0))) dy = -dy;
+    if (dy) Compress(r, s, t, (unsigned) 2*dy, FALSE, grow);
+    XOffsetRegion(r, dx, dy);
+    XDestroyRegion(s);
+    XDestroyRegion(t);
+    return 0;
+}
+
+
+/*======================================================================
+ *	    Region Intersection
+ *====================================================================*/
+/*-
+ *-----------------------------------------------------------------------
+ * miIntersectO --
+ *	Handle an overlapping band for miIntersect.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	Rectangles may be added to the region.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static void*/
+static int
+miIntersectO (
+    register Region	pReg,
+    register BoxPtr	r1,
+    BoxPtr  	  	r1End,
+    register BoxPtr	r2,
+    BoxPtr  	  	r2End,
+    short    	  	y1,
+    short    	  	y2)
+{
+    register short  	x1;
+    register short  	x2;
+    register BoxPtr	pNextRect;
+
+    pNextRect = &pReg->rects[pReg->numRects];
+
+    while ((r1 != r1End) && (r2 != r2End))
+    {
+	x1 = max(r1->x1,r2->x1);
+	x2 = min(r1->x2,r2->x2);
+
+	/*
+	 * If there's any overlap between the two rectangles, add that
+	 * overlap to the new region.
+	 * There's no need to check for subsumption because the only way
+	 * such a need could arise is if some region has two rectangles
+	 * right next to each other. Since that should never happen...
+	 */
+	if (x1 < x2)
+	{
+	    assert(y1<y2);
+
+	    MEMCHECK(pReg, pNextRect, pReg->rects);
+	    pNextRect->x1 = x1;
+	    pNextRect->y1 = y1;
+	    pNextRect->x2 = x2;
+	    pNextRect->y2 = y2;
+	    pReg->numRects += 1;
+	    pNextRect++;
+	    assert(pReg->numRects <= pReg->size);
+	}
+
+	/*
+	 * Need to advance the pointers. Shift the one that extends
+	 * to the right the least, since the other still has a chance to
+	 * overlap with that region's next rectangle, if you see what I mean.
+	 */
+	if (r1->x2 < r2->x2)
+	{
+	    r1++;
+	}
+	else if (r2->x2 < r1->x2)
+	{
+	    r2++;
+	}
+	else
+	{
+	    r1++;
+	    r2++;
+	}
+    }
+    return 0;	/* lint */
+}
+
+int
+XIntersectRegion(
+    Region 	  	reg1,
+    Region	  	reg2,          /* source regions     */
+    register Region 	newReg)               /* destination Region */
+{
+   /* check for trivial reject */
+    if ( (!(reg1->numRects)) || (!(reg2->numRects))  ||
+	(!EXTENTCHECK(&reg1->extents, &reg2->extents)))
+        newReg->numRects = 0;
+    else
+	miRegionOp (newReg, reg1, reg2,
+    		miIntersectO, NULL, NULL);
+
+    /*
+     * Can't alter newReg's extents before we call miRegionOp because
+     * it might be one of the source regions and miRegionOp depends
+     * on the extents of those regions being the same. Besides, this
+     * way there's no checking against rectangles that will be nuked
+     * due to coalescing, so we have to examine fewer rectangles.
+     */
+    miSetExtents(newReg);
+    return 1;
+}
+
+static void
+miRegionCopy(
+    register Region dstrgn,
+    register Region rgn)
+
+{
+    if (dstrgn != rgn) /*  don't want to copy to itself */
+    {
+        if (dstrgn->size < rgn->numRects)
+        {
+            if (dstrgn->rects)
+            {
+		BOX *prevRects = dstrgn->rects;
+
+                if (! (dstrgn->rects = (BOX *)
+		       Xrealloc((char *) dstrgn->rects,
+				(unsigned) rgn->numRects * (sizeof(BOX))))) {
+		    Xfree(prevRects);
+		    return;
+		}
+            }
+            dstrgn->size = rgn->numRects;
+	}
+        dstrgn->numRects = rgn->numRects;
+        dstrgn->extents.x1 = rgn->extents.x1;
+        dstrgn->extents.y1 = rgn->extents.y1;
+        dstrgn->extents.x2 = rgn->extents.x2;
+        dstrgn->extents.y2 = rgn->extents.y2;
+
+	memcpy((char *) dstrgn->rects, (char *) rgn->rects,
+	       (int) (rgn->numRects * sizeof(BOX)));
+    }
+}
+
+/*======================================================================
+ *	    Generic Region Operator
+ *====================================================================*/
+
+/*-
+ *-----------------------------------------------------------------------
+ * miCoalesce --
+ *	Attempt to merge the boxes in the current band with those in the
+ *	previous one. Used only by miRegionOp.
+ *
+ * Results:
+ *	The new index for the previous band.
+ *
+ * Side Effects:
+ *	If coalescing takes place:
+ *	    - rectangles in the previous band will have their y2 fields
+ *	      altered.
+ *	    - pReg->numRects will be decreased.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static int*/
+static int
+miCoalesce(
+    register Region	pReg,	    	/* Region to coalesce */
+    int	    	  	prevStart,  	/* Index of start of previous band */
+    int	    	  	curStart)   	/* Index of start of current band */
+{
+    register BoxPtr	pPrevBox;   	/* Current box in previous band */
+    register BoxPtr	pCurBox;    	/* Current box in current band */
+    register BoxPtr	pRegEnd;    	/* End of region */
+    int	    	  	curNumRects;	/* Number of rectangles in current
+					 * band */
+    int	    	  	prevNumRects;	/* Number of rectangles in previous
+					 * band */
+    int	    	  	bandY1;	    	/* Y1 coordinate for current band */
+
+    pRegEnd = &pReg->rects[pReg->numRects];
+
+    pPrevBox = &pReg->rects[prevStart];
+    prevNumRects = curStart - prevStart;
+
+    /*
+     * Figure out how many rectangles are in the current band. Have to do
+     * this because multiple bands could have been added in miRegionOp
+     * at the end when one region has been exhausted.
+     */
+    pCurBox = &pReg->rects[curStart];
+    bandY1 = pCurBox->y1;
+    for (curNumRects = 0;
+	 (pCurBox != pRegEnd) && (pCurBox->y1 == bandY1);
+	 curNumRects++)
+    {
+	pCurBox++;
+    }
+
+    if (pCurBox != pRegEnd)
+    {
+	/*
+	 * If more than one band was added, we have to find the start
+	 * of the last band added so the next coalescing job can start
+	 * at the right place... (given when multiple bands are added,
+	 * this may be pointless -- see above).
+	 */
+	pRegEnd--;
+	while (pRegEnd[-1].y1 == pRegEnd->y1)
+	{
+	    pRegEnd--;
+	}
+	curStart = pRegEnd - pReg->rects;
+	pRegEnd = pReg->rects + pReg->numRects;
+    }
+
+    if ((curNumRects == prevNumRects) && (curNumRects != 0)) {
+	pCurBox -= curNumRects;
+	/*
+	 * The bands may only be coalesced if the bottom of the previous
+	 * matches the top scanline of the current.
+	 */
+	if (pPrevBox->y2 == pCurBox->y1)
+	{
+	    /*
+	     * Make sure the bands have boxes in the same places. This
+	     * assumes that boxes have been added in such a way that they
+	     * cover the most area possible. I.e. two boxes in a band must
+	     * have some horizontal space between them.
+	     */
+	    do
+	    {
+		if ((pPrevBox->x1 != pCurBox->x1) ||
+		    (pPrevBox->x2 != pCurBox->x2))
+		{
+		    /*
+		     * The bands don't line up so they can't be coalesced.
+		     */
+		    return (curStart);
+		}
+		pPrevBox++;
+		pCurBox++;
+		prevNumRects -= 1;
+	    } while (prevNumRects != 0);
+
+	    pReg->numRects -= curNumRects;
+	    pCurBox -= curNumRects;
+	    pPrevBox -= curNumRects;
+
+	    /*
+	     * The bands may be merged, so set the bottom y of each box
+	     * in the previous band to that of the corresponding box in
+	     * the current band.
+	     */
+	    do
+	    {
+		pPrevBox->y2 = pCurBox->y2;
+		pPrevBox++;
+		pCurBox++;
+		curNumRects -= 1;
+	    } while (curNumRects != 0);
+
+	    /*
+	     * If only one band was added to the region, we have to backup
+	     * curStart to the start of the previous band.
+	     *
+	     * If more than one band was added to the region, copy the
+	     * other bands down. The assumption here is that the other bands
+	     * came from the same region as the current one and no further
+	     * coalescing can be done on them since it's all been done
+	     * already... curStart is already in the right place.
+	     */
+	    if (pCurBox == pRegEnd)
+	    {
+		curStart = prevStart;
+	    }
+	    else
+	    {
+		do
+		{
+		    *pPrevBox++ = *pCurBox++;
+		} while (pCurBox != pRegEnd);
+	    }
+
+	}
+    }
+    return (curStart);
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miRegionOp --
+ *	Apply an operation to two regions. Called by miUnion, miInverse,
+ *	miSubtract, miIntersect...
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	The new region is overwritten.
+ *
+ * Notes:
+ *	The idea behind this function is to view the two regions as sets.
+ *	Together they cover a rectangle of area that this function divides
+ *	into horizontal bands where points are covered only by one region
+ *	or by both. For the first case, the nonOverlapFunc is called with
+ *	each the band and the band's upper and lower extents. For the
+ *	second, the overlapFunc is called to process the entire band. It
+ *	is responsible for clipping the rectangles in the band, though
+ *	this function provides the boundaries.
+ *	At the end of each band, the new region is coalesced, if possible,
+ *	to reduce the number of rectangles in the region.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static void*/
+static void
+miRegionOp(
+    register Region 	newReg,	    	    	/* Place to store result */
+    Region	  	reg1,	    	    	/* First region in operation */
+    Region	  	reg2,	    	    	/* 2d region in operation */
+    int    	  	(*overlapFunc)(
+        register Region     pReg,
+        register BoxPtr     r1,
+        BoxPtr              r1End,
+        register BoxPtr     r2,
+        BoxPtr              r2End,
+        short               y1,
+        short               y2),                /* Function to call for over-
+						 * lapping bands */
+    int    	  	(*nonOverlap1Func)(
+        register Region     pReg,
+        register BoxPtr     r,
+        BoxPtr              rEnd,
+        register short      y1,
+        register short      y2),                /* Function to call for non-
+						 * overlapping bands in region
+						 * 1 */
+    int    	  	(*nonOverlap2Func)(
+        register Region     pReg,
+        register BoxPtr     r,
+        BoxPtr              rEnd,
+        register short      y1,
+        register short      y2))                /* Function to call for non-
+						 * overlapping bands in region
+						 * 2 */
+{
+    register BoxPtr	r1; 	    	    	/* Pointer into first region */
+    register BoxPtr	r2; 	    	    	/* Pointer into 2d region */
+    BoxPtr  	  	r1End;	    	    	/* End of 1st region */
+    BoxPtr  	  	r2End;	    	    	/* End of 2d region */
+    register short  	ybot;	    	    	/* Bottom of intersection */
+    register short  	ytop;	    	    	/* Top of intersection */
+    BoxPtr  	  	oldRects;   	    	/* Old rects for newReg */
+    int	    	  	prevBand;   	    	/* Index of start of
+						 * previous band in newReg */
+    int	    	  	curBand;    	    	/* Index of start of current
+						 * band in newReg */
+    register BoxPtr 	r1BandEnd;  	    	/* End of current band in r1 */
+    register BoxPtr 	r2BandEnd;  	    	/* End of current band in r2 */
+    short     	  	top;	    	    	/* Top of non-overlapping
+						 * band */
+    short     	  	bot;	    	    	/* Bottom of non-overlapping
+						 * band */
+
+    /*
+     * Initialization:
+     *	set r1, r2, r1End and r2End appropriately, preserve the important
+     * parts of the destination region until the end in case it's one of
+     * the two source regions, then mark the "new" region empty, allocating
+     * another array of rectangles for it to use.
+     */
+    r1 = reg1->rects;
+    r2 = reg2->rects;
+    r1End = r1 + reg1->numRects;
+    r2End = r2 + reg2->numRects;
+
+    oldRects = newReg->rects;
+
+    EMPTY_REGION(newReg);
+
+    /*
+     * Allocate a reasonable number of rectangles for the new region. The idea
+     * is to allocate enough so the individual functions don't need to
+     * reallocate and copy the array, which is time consuming, yet we don't
+     * have to worry about using too much memory. I hope to be able to
+     * nuke the Xrealloc() at the end of this function eventually.
+     */
+    newReg->size = max(reg1->numRects,reg2->numRects) * 2;
+
+    if (! (newReg->rects = (BoxPtr)
+	   Xmalloc ((unsigned) (sizeof(BoxRec) * newReg->size)))) {
+	newReg->size = 0;
+	return;
+    }
+
+    /*
+     * Initialize ybot and ytop.
+     * In the upcoming loop, ybot and ytop serve different functions depending
+     * on whether the band being handled is an overlapping or non-overlapping
+     * band.
+     * 	In the case of a non-overlapping band (only one of the regions
+     * has points in the band), ybot is the bottom of the most recent
+     * intersection and thus clips the top of the rectangles in that band.
+     * ytop is the top of the next intersection between the two regions and
+     * serves to clip the bottom of the rectangles in the current band.
+     *	For an overlapping band (where the two regions intersect), ytop clips
+     * the top of the rectangles of both regions and ybot clips the bottoms.
+     */
+    if (reg1->extents.y1 < reg2->extents.y1)
+	ybot = reg1->extents.y1;
+    else
+	ybot = reg2->extents.y1;
+
+    /*
+     * prevBand serves to mark the start of the previous band so rectangles
+     * can be coalesced into larger rectangles. qv. miCoalesce, above.
+     * In the beginning, there is no previous band, so prevBand == curBand
+     * (curBand is set later on, of course, but the first band will always
+     * start at index 0). prevBand and curBand must be indices because of
+     * the possible expansion, and resultant moving, of the new region's
+     * array of rectangles.
+     */
+    prevBand = 0;
+
+    do
+    {
+	curBand = newReg->numRects;
+
+	/*
+	 * This algorithm proceeds one source-band (as opposed to a
+	 * destination band, which is determined by where the two regions
+	 * intersect) at a time. r1BandEnd and r2BandEnd serve to mark the
+	 * rectangle after the last one in the current band for their
+	 * respective regions.
+	 */
+	r1BandEnd = r1;
+	while ((r1BandEnd != r1End) && (r1BandEnd->y1 == r1->y1))
+	{
+	    r1BandEnd++;
+	}
+
+	r2BandEnd = r2;
+	while ((r2BandEnd != r2End) && (r2BandEnd->y1 == r2->y1))
+	{
+	    r2BandEnd++;
+	}
+
+	/*
+	 * First handle the band that doesn't intersect, if any.
+	 *
+	 * Note that attention is restricted to one band in the
+	 * non-intersecting region at once, so if a region has n
+	 * bands between the current position and the next place it overlaps
+	 * the other, this entire loop will be passed through n times.
+	 */
+	if (r1->y1 < r2->y1)
+	{
+	    top = max(r1->y1,ybot);
+	    bot = min(r1->y2,r2->y1);
+
+	    if ((top != bot) && (nonOverlap1Func != NULL))
+	    {
+		(* nonOverlap1Func) (newReg, r1, r1BandEnd, top, bot);
+	    }
+
+	    ytop = r2->y1;
+	}
+	else if (r2->y1 < r1->y1)
+	{
+	    top = max(r2->y1,ybot);
+	    bot = min(r2->y2,r1->y1);
+
+	    if ((top != bot) && (nonOverlap2Func != NULL))
+	    {
+		(* nonOverlap2Func) (newReg, r2, r2BandEnd, top, bot);
+	    }
+
+	    ytop = r1->y1;
+	}
+	else
+	{
+	    ytop = r1->y1;
+	}
+
+	/*
+	 * If any rectangles got added to the region, try and coalesce them
+	 * with rectangles from the previous band. Note we could just do
+	 * this test in miCoalesce, but some machines incur a not
+	 * inconsiderable cost for function calls, so...
+	 */
+	if (newReg->numRects != curBand)
+	{
+	    prevBand = miCoalesce (newReg, prevBand, curBand);
+	}
+
+	/*
+	 * Now see if we've hit an intersecting band. The two bands only
+	 * intersect if ybot > ytop
+	 */
+	ybot = min(r1->y2, r2->y2);
+	curBand = newReg->numRects;
+	if (ybot > ytop)
+	{
+	    (* overlapFunc) (newReg, r1, r1BandEnd, r2, r2BandEnd, ytop, ybot);
+
+	}
+
+	if (newReg->numRects != curBand)
+	{
+	    prevBand = miCoalesce (newReg, prevBand, curBand);
+	}
+
+	/*
+	 * If we've finished with a band (y2 == ybot) we skip forward
+	 * in the region to the next band.
+	 */
+	if (r1->y2 == ybot)
+	{
+	    r1 = r1BandEnd;
+	}
+	if (r2->y2 == ybot)
+	{
+	    r2 = r2BandEnd;
+	}
+    } while ((r1 != r1End) && (r2 != r2End));
+
+    /*
+     * Deal with whichever region still has rectangles left.
+     */
+    curBand = newReg->numRects;
+    if (r1 != r1End)
+    {
+	if (nonOverlap1Func != NULL)
+	{
+	    do
+	    {
+		r1BandEnd = r1;
+		while ((r1BandEnd < r1End) && (r1BandEnd->y1 == r1->y1))
+		{
+		    r1BandEnd++;
+		}
+		(* nonOverlap1Func) (newReg, r1, r1BandEnd,
+				     max(r1->y1,ybot), r1->y2);
+		r1 = r1BandEnd;
+	    } while (r1 != r1End);
+	}
+    }
+    else if ((r2 != r2End) && (nonOverlap2Func != NULL))
+    {
+	do
+	{
+	    r2BandEnd = r2;
+	    while ((r2BandEnd < r2End) && (r2BandEnd->y1 == r2->y1))
+	    {
+		 r2BandEnd++;
+	    }
+	    (* nonOverlap2Func) (newReg, r2, r2BandEnd,
+				max(r2->y1,ybot), r2->y2);
+	    r2 = r2BandEnd;
+	} while (r2 != r2End);
+    }
+
+    if (newReg->numRects != curBand)
+    {
+	(void) miCoalesce (newReg, prevBand, curBand);
+    }
+
+    /*
+     * A bit of cleanup. To keep regions from growing without bound,
+     * we shrink the array of rectangles to match the new number of
+     * rectangles in the region. This never goes to 0, however...
+     *
+     * Only do this stuff if the number of rectangles allocated is more than
+     * twice the number of rectangles in the region (a simple optimization...).
+     */
+    if (newReg->numRects < (newReg->size >> 1))
+    {
+	if (REGION_NOT_EMPTY(newReg))
+	{
+	    BoxPtr prev_rects = newReg->rects;
+	    newReg->size = newReg->numRects;
+	    newReg->rects = (BoxPtr) Xrealloc ((char *) newReg->rects,
+				   (unsigned) (sizeof(BoxRec) * newReg->size));
+	    if (! newReg->rects)
+		newReg->rects = prev_rects;
+	}
+	else
+	{
+	    /*
+	     * No point in doing the extra work involved in an Xrealloc if
+	     * the region is empty
+	     */
+	    newReg->size = 1;
+	    Xfree((char *) newReg->rects);
+	    newReg->rects = (BoxPtr) Xmalloc(sizeof(BoxRec));
+	}
+    }
+    Xfree ((char *) oldRects);
+    return;
+}
+
+
+/*======================================================================
+ *	    Region Union
+ *====================================================================*/
+
+/*-
+ *-----------------------------------------------------------------------
+ * miUnionNonO --
+ *	Handle a non-overlapping band for the union operation. Just
+ *	Adds the rectangles into the region. Doesn't have to check for
+ *	subsumption or anything.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	pReg->numRects is incremented and the final rectangles overwritten
+ *	with the rectangles we're passed.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static void*/
+static int
+miUnionNonO (
+    register Region	pReg,
+    register BoxPtr	r,
+    BoxPtr  	  	rEnd,
+    register short  	y1,
+    register short  	y2)
+{
+    register BoxPtr	pNextRect;
+
+    pNextRect = &pReg->rects[pReg->numRects];
+
+    assert(y1 < y2);
+
+    while (r != rEnd)
+    {
+	assert(r->x1 < r->x2);
+	MEMCHECK(pReg, pNextRect, pReg->rects);
+	pNextRect->x1 = r->x1;
+	pNextRect->y1 = y1;
+	pNextRect->x2 = r->x2;
+	pNextRect->y2 = y2;
+	pReg->numRects += 1;
+	pNextRect++;
+
+	assert(pReg->numRects<=pReg->size);
+	r++;
+    }
+    return 0;	/* lint */
+}
+
+
+/*-
+ *-----------------------------------------------------------------------
+ * miUnionO --
+ *	Handle an overlapping band for the union operation. Picks the
+ *	left-most rectangle each time and merges it into the region.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	Rectangles are overwritten in pReg->rects and pReg->numRects will
+ *	be changed.
+ *
+ *-----------------------------------------------------------------------
+ */
+
+/* static void*/
+static int
+miUnionO (
+    register Region	pReg,
+    register BoxPtr	r1,
+    BoxPtr  	  	r1End,
+    register BoxPtr	r2,
+    BoxPtr  	  	r2End,
+    register short	y1,
+    register short	y2)
+{
+    register BoxPtr	pNextRect;
+
+    pNextRect = &pReg->rects[pReg->numRects];
+
+#define MERGERECT(r) \
+    if ((pReg->numRects != 0) &&  \
+	(pNextRect[-1].y1 == y1) &&  \
+	(pNextRect[-1].y2 == y2) &&  \
+	(pNextRect[-1].x2 >= r->x1))  \
+    {  \
+	if (pNextRect[-1].x2 < r->x2)  \
+	{  \
+	    pNextRect[-1].x2 = r->x2;  \
+	    assert(pNextRect[-1].x1<pNextRect[-1].x2); \
+	}  \
+    }  \
+    else  \
+    {  \
+	MEMCHECK(pReg, pNextRect, pReg->rects);  \
+	pNextRect->y1 = y1;  \
+	pNextRect->y2 = y2;  \
+	pNextRect->x1 = r->x1;  \
+	pNextRect->x2 = r->x2;  \
+	pReg->numRects += 1;  \
+        pNextRect += 1;  \
+    }  \
+    assert(pReg->numRects<=pReg->size);\
+    r++;
+
+    assert (y1<y2);
+    while ((r1 != r1End) && (r2 != r2End))
+    {
+	if (r1->x1 < r2->x1)
+	{
+	    MERGERECT(r1);
+	}
+	else
+	{
+	    MERGERECT(r2);
+	}
+    }
+
+    if (r1 != r1End)
+    {
+	do
+	{
+	    MERGERECT(r1);
+	} while (r1 != r1End);
+    }
+    else while (r2 != r2End)
+    {
+	MERGERECT(r2);
+    }
+    return 0;	/* lint */
+}
+
+int
+XUnionRegion(
+    Region 	  reg1,
+    Region	  reg2,             /* source regions     */
+    Region 	  newReg)                  /* destination Region */
+{
+    /*  checks all the simple cases */
+
+    /*
+     * Region 1 and 2 are the same or region 1 is empty
+     */
+    if ( (reg1 == reg2) || (!(reg1->numRects)) )
+    {
+        if (newReg != reg2)
+            miRegionCopy(newReg, reg2);
+        return 1;
+    }
+
+    /*
+     * if nothing to union (region 2 empty)
+     */
+    if (!(reg2->numRects))
+    {
+        if (newReg != reg1)
+            miRegionCopy(newReg, reg1);
+        return 1;
+    }
+
+    /*
+     * Region 1 completely subsumes region 2
+     */
+    if ((reg1->numRects == 1) &&
+	(reg1->extents.x1 <= reg2->extents.x1) &&
+	(reg1->extents.y1 <= reg2->extents.y1) &&
+	(reg1->extents.x2 >= reg2->extents.x2) &&
+	(reg1->extents.y2 >= reg2->extents.y2))
+    {
+        if (newReg != reg1)
+            miRegionCopy(newReg, reg1);
+        return 1;
+    }
+
+    /*
+     * Region 2 completely subsumes region 1
+     */
+    if ((reg2->numRects == 1) &&
+	(reg2->extents.x1 <= reg1->extents.x1) &&
+	(reg2->extents.y1 <= reg1->extents.y1) &&
+	(reg2->extents.x2 >= reg1->extents.x2) &&
+	(reg2->extents.y2 >= reg1->extents.y2))
+    {
+        if (newReg != reg2)
+            miRegionCopy(newReg, reg2);
+        return 1;
+    }
+
+    miRegionOp (newReg, reg1, reg2, miUnionO,
+    		miUnionNonO, miUnionNonO);
+
+    newReg->extents.x1 = min(reg1->extents.x1, reg2->extents.x1);
+    newReg->extents.y1 = min(reg1->extents.y1, reg2->extents.y1);
+    newReg->extents.x2 = max(reg1->extents.x2, reg2->extents.x2);
+    newReg->extents.y2 = max(reg1->extents.y2, reg2->extents.y2);
+
+    return 1;
+}
+
+
+/*======================================================================
+ * 	    	  Region Subtraction
+ *====================================================================*/
+
+/*-
+ *-----------------------------------------------------------------------
+ * miSubtractNonO --
+ *	Deal with non-overlapping band for subtraction. Any parts from
+ *	region 2 we discard. Anything from region 1 we add to the region.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	pReg may be affected.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static void*/
+static int
+miSubtractNonO1 (
+    register Region	pReg,
+    register BoxPtr	r,
+    BoxPtr  	  	rEnd,
+    register short  	y1,
+    register short   	y2)
+{
+    register BoxPtr	pNextRect;
+
+    pNextRect = &pReg->rects[pReg->numRects];
+
+    assert(y1<y2);
+
+    while (r != rEnd)
+    {
+	assert(r->x1<r->x2);
+	MEMCHECK(pReg, pNextRect, pReg->rects);
+	pNextRect->x1 = r->x1;
+	pNextRect->y1 = y1;
+	pNextRect->x2 = r->x2;
+	pNextRect->y2 = y2;
+	pReg->numRects += 1;
+	pNextRect++;
+
+	assert(pReg->numRects <= pReg->size);
+
+	r++;
+    }
+    return 0;	/* lint */
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miSubtractO --
+ *	Overlapping band subtraction. x1 is the left-most point not yet
+ *	checked.
+ *
+ * Results:
+ *	None.
+ *
+ * Side Effects:
+ *	pReg may have rectangles added to it.
+ *
+ *-----------------------------------------------------------------------
+ */
+/* static void*/
+static int
+miSubtractO (
+    register Region	pReg,
+    register BoxPtr	r1,
+    BoxPtr  	  	r1End,
+    register BoxPtr	r2,
+    BoxPtr  	  	r2End,
+    register short  	y1,
+    register short  	y2)
+{
+    register BoxPtr	pNextRect;
+    register int  	x1;
+
+    x1 = r1->x1;
+
+    assert(y1<y2);
+    pNextRect = &pReg->rects[pReg->numRects];
+
+    while ((r1 != r1End) && (r2 != r2End))
+    {
+	if (r2->x2 <= x1)
+	{
+	    /*
+	     * Subtrahend missed the boat: go to next subtrahend.
+	     */
+	    r2++;
+	}
+	else if (r2->x1 <= x1)
+	{
+	    /*
+	     * Subtrahend preceeds minuend: nuke left edge of minuend.
+	     */
+	    x1 = r2->x2;
+	    if (x1 >= r1->x2)
+	    {
+		/*
+		 * Minuend completely covered: advance to next minuend and
+		 * reset left fence to edge of new minuend.
+		 */
+		r1++;
+		if (r1 != r1End)
+		    x1 = r1->x1;
+	    }
+	    else
+	    {
+		/*
+		 * Subtrahend now used up since it doesn't extend beyond
+		 * minuend
+		 */
+		r2++;
+	    }
+	}
+	else if (r2->x1 < r1->x2)
+	{
+	    /*
+	     * Left part of subtrahend covers part of minuend: add uncovered
+	     * part of minuend to region and skip to next subtrahend.
+	     */
+	    assert(x1<r2->x1);
+	    MEMCHECK(pReg, pNextRect, pReg->rects);
+	    pNextRect->x1 = x1;
+	    pNextRect->y1 = y1;
+	    pNextRect->x2 = r2->x1;
+	    pNextRect->y2 = y2;
+	    pReg->numRects += 1;
+	    pNextRect++;
+
+	    assert(pReg->numRects<=pReg->size);
+
+	    x1 = r2->x2;
+	    if (x1 >= r1->x2)
+	    {
+		/*
+		 * Minuend used up: advance to new...
+		 */
+		r1++;
+		if (r1 != r1End)
+		    x1 = r1->x1;
+	    }
+	    else
+	    {
+		/*
+		 * Subtrahend used up
+		 */
+		r2++;
+	    }
+	}
+	else
+	{
+	    /*
+	     * Minuend used up: add any remaining piece before advancing.
+	     */
+	    if (r1->x2 > x1)
+	    {
+		MEMCHECK(pReg, pNextRect, pReg->rects);
+		pNextRect->x1 = x1;
+		pNextRect->y1 = y1;
+		pNextRect->x2 = r1->x2;
+		pNextRect->y2 = y2;
+		pReg->numRects += 1;
+		pNextRect++;
+		assert(pReg->numRects<=pReg->size);
+	    }
+	    r1++;
+	    if (r1 != r1End)
+		x1 = r1->x1;
+	}
+    }
+
+    /*
+     * Add remaining minuend rectangles to region.
+     */
+    while (r1 != r1End)
+    {
+	assert(x1<r1->x2);
+	MEMCHECK(pReg, pNextRect, pReg->rects);
+	pNextRect->x1 = x1;
+	pNextRect->y1 = y1;
+	pNextRect->x2 = r1->x2;
+	pNextRect->y2 = y2;
+	pReg->numRects += 1;
+	pNextRect++;
+
+	assert(pReg->numRects<=pReg->size);
+
+	r1++;
+	if (r1 != r1End)
+	{
+	    x1 = r1->x1;
+	}
+    }
+    return 0;	/* lint */
+}
+
+/*-
+ *-----------------------------------------------------------------------
+ * miSubtract --
+ *	Subtract regS from regM and leave the result in regD.
+ *	S stands for subtrahend, M for minuend and D for difference.
+ *
+ * Results:
+ *	TRUE.
+ *
+ * Side Effects:
+ *	regD is overwritten.
+ *
+ *-----------------------------------------------------------------------
+ */
+
+int
+XSubtractRegion(
+    Region 	  	regM,
+    Region	  	regS,
+    register Region	regD)
+{
+   /* check for trivial reject */
+    if ( (!(regM->numRects)) || (!(regS->numRects))  ||
+	(!EXTENTCHECK(&regM->extents, &regS->extents)) )
+    {
+	miRegionCopy(regD, regM);
+        return 1;
+    }
+
+    miRegionOp (regD, regM, regS, miSubtractO,
+    		miSubtractNonO1, NULL);
+
+    /*
+     * Can't alter newReg's extents before we call miRegionOp because
+     * it might be one of the source regions and miRegionOp depends
+     * on the extents of those regions being the unaltered. Besides, this
+     * way there's no checking against rectangles that will be nuked
+     * due to coalescing, so we have to examine fewer rectangles.
+     */
+    miSetExtents (regD);
+    return 1;
+}
+
+int
+XXorRegion(Region sra, Region srb, Region dr)
+{
+    Region tra, trb;
+
+    if (! (tra = XCreateRegion()) )
+	return 0;
+    if (! (trb = XCreateRegion()) ) {
+	XDestroyRegion(tra);
+	return 0;
+    }
+    (void) XSubtractRegion(sra,srb,tra);
+    (void) XSubtractRegion(srb,sra,trb);
+    (void) XUnionRegion(tra,trb,dr);
+    XDestroyRegion(tra);
+    XDestroyRegion(trb);
+    return 0;
+}
+
+/*
+ * Check to see if the region is empty.  Assumes a region is passed
+ * as a parameter
+ */
+int
+XEmptyRegion(
+    Region r)
+{
+    if( r->numRects == 0 ) return TRUE;
+    else  return FALSE;
+}
+
+/*
+ *	Check to see if two regions are equal
+ */
+int
+XEqualRegion(Region r1, Region r2)
+{
+    int i;
+
+    if( r1->numRects != r2->numRects ) return FALSE;
+    else if( r1->numRects == 0 ) return TRUE;
+    else if ( r1->extents.x1 != r2->extents.x1 ) return FALSE;
+    else if ( r1->extents.x2 != r2->extents.x2 ) return FALSE;
+    else if ( r1->extents.y1 != r2->extents.y1 ) return FALSE;
+    else if ( r1->extents.y2 != r2->extents.y2 ) return FALSE;
+    else for( i=0; i < r1->numRects; i++ ) {
+    	if ( r1->rects[i].x1 != r2->rects[i].x1 ) return FALSE;
+    	else if ( r1->rects[i].x2 != r2->rects[i].x2 ) return FALSE;
+    	else if ( r1->rects[i].y1 != r2->rects[i].y1 ) return FALSE;
+    	else if ( r1->rects[i].y2 != r2->rects[i].y2 ) return FALSE;
+    }
+    return TRUE;
+}
+
+int
+XPointInRegion(
+    Region pRegion,
+    int x, int y)
+{
+    int i;
+
+    if (pRegion->numRects == 0)
+        return FALSE;
+    if (!INBOX(pRegion->extents, x, y))
+        return FALSE;
+    for (i=0; i<pRegion->numRects; i++)
+    {
+        if (INBOX (pRegion->rects[i], x, y))
+	    return TRUE;
+    }
+    return FALSE;
+}
+
+int
+XRectInRegion(
+    register Region	region,
+    int rx, int ry,
+    unsigned int rwidth, unsigned int rheight)
+{
+    register BoxPtr pbox;
+    register BoxPtr pboxEnd;
+    Box rect;
+    register BoxPtr prect = &rect;
+    int      partIn, partOut;
+
+    prect->x1 = rx;
+    prect->y1 = ry;
+    prect->x2 = rwidth + rx;
+    prect->y2 = rheight + ry;
+
+    /* this is (just) a useful optimization */
+    if ((region->numRects == 0) || !EXTENTCHECK(&region->extents, prect))
+        return(RectangleOut);
+
+    partOut = FALSE;
+    partIn = FALSE;
+
+    /* can stop when both partOut and partIn are TRUE, or we reach prect->y2 */
+    for (pbox = region->rects, pboxEnd = pbox + region->numRects;
+	 pbox < pboxEnd;
+	 pbox++)
+    {
+
+	if (pbox->y2 <= ry)
+	   continue;	/* getting up to speed or skipping remainder of band */
+
+	if (pbox->y1 > ry)
+	{
+	   partOut = TRUE;	/* missed part of rectangle above */
+	   if (partIn || (pbox->y1 >= prect->y2))
+	      break;
+	   ry = pbox->y1;	/* x guaranteed to be == prect->x1 */
+	}
+
+	if (pbox->x2 <= rx)
+	   continue;		/* not far enough over yet */
+
+	if (pbox->x1 > rx)
+	{
+	   partOut = TRUE;	/* missed part of rectangle to left */
+	   if (partIn)
+	      break;
+	}
+
+	if (pbox->x1 < prect->x2)
+	{
+	    partIn = TRUE;	/* definitely overlap */
+	    if (partOut)
+	       break;
+	}
+
+	if (pbox->x2 >= prect->x2)
+	{
+	   ry = pbox->y2;	/* finished with this band */
+	   if (ry >= prect->y2)
+	      break;
+	   rx = prect->x1;	/* reset x out to left again */
+	} else
+	{
+	    /*
+	     * Because boxes in a band are maximal width, if the first box
+	     * to overlap the rectangle doesn't completely cover it in that
+	     * band, the rectangle must be partially out, since some of it
+	     * will be uncovered in that band. partIn will have been set true
+	     * by now...
+	     */
+	    break;
+	}
+
+    }
+
+    return(partIn ? ((ry < prect->y2) ? RectanglePart : RectangleIn) :
+		RectangleOut);
+}