summaryrefslogtreecommitdiff
path: root/mi/mivaltree.c
blob: 2585422bc2e75f892e5f2f107f1a872517adf1f3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
/*
 * mivaltree.c --
 *	Functions for recalculating window clip lists. Main function
 *	is miValidateTree.
 *

Copyright 1987, 1988, 1989, 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, 1989 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 panoramix components contained the following notice */
/*****************************************************************

Copyright (c) 1991, 1997 Digital Equipment Corporation, Maynard, Massachusetts.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software.

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
DIGITAL EQUIPMENT CORPORATION BE LIABLE FOR ANY CLAIM, DAMAGES, INCLUDING,
BUT NOT LIMITED TO CONSEQUENTIAL OR INCIDENTAL 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 Digital Equipment Corporation
shall not be used in advertising or otherwise to promote the sale, use or other
dealings in this Software without prior written authorization from Digital
Equipment Corporation.

******************************************************************/


 /* 
  * Aug '86: Susan Angebranndt -- original code
  * July '87: Adam de Boor -- substantially modified and commented
  * Summer '89: Joel McCormack -- so fast you wouldn't believe it possible.
  *             In particular, much improved code for window mapping and
  *             circulating.
  *		Bob Scheifler -- avoid miComputeClips for unmapped windows,
  *				 valdata changes
  */
#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include    <X11/X.h>
#include    "scrnintstr.h"
#include    "validate.h"
#include    "windowstr.h"
#include    "mi.h"
#include    "regionstr.h"
#include    "mivalidate.h"

#include    "globals.h"

/*
 * Compute the visibility of a shaped window
 */
int
miShapedWindowIn (ScreenPtr pScreen, RegionPtr universe, RegionPtr bounding,
                  BoxPtr rect, int x, int y)
{
    BoxRec  	box;
    BoxPtr	boundBox;
    int		nbox;
    Bool	someIn, someOut;
    int 	t, x1, y1, x2, y2;

    nbox = REGION_NUM_RECTS (bounding);
    boundBox = REGION_RECTS (bounding);
    someIn = someOut = FALSE;
    x1 = rect->x1;
    y1 = rect->y1;
    x2 = rect->x2;
    y2 = rect->y2;
    while (nbox--)
    {
	if ((t = boundBox->x1 + x) < x1)
	    t = x1;
	box.x1 = t;
	if ((t = boundBox->y1 + y) < y1)
	    t = y1;
	box.y1 = t;
	if ((t = boundBox->x2 + x) > x2)
	    t = x2;
	box.x2 = t;
	if ((t = boundBox->y2 + y) > y2)
	    t = y2;
	box.y2 = t;
	if (box.x1 > box.x2)
	    box.x2 = box.x1;
	if (box.y1 > box.y2)
	    box.y2 = box.y1;
	switch (RECT_IN_REGION(pScreen, universe, &box))
	{
	case rgnIN:
	    if (someOut)
		return rgnPART;
	    someIn = TRUE;
	    break;
	case rgnOUT:
	    if (someIn)
		return rgnPART;
	    someOut = TRUE;
	    break;
	default:
	    return rgnPART;
	}
	boundBox++;
    }
    if (someIn)
	return rgnIN;
    return rgnOUT;
}

static GetRedirectBorderClipProcPtr	miGetRedirectBorderClipProc;
static SetRedirectBorderClipProcPtr	miSetRedirectBorderClipProc;

void
miRegisterRedirectBorderClipProc (SetRedirectBorderClipProcPtr setBorderClip,
				  GetRedirectBorderClipProcPtr getBorderClip)
{
    miSetRedirectBorderClipProc = setBorderClip;
    miGetRedirectBorderClipProc = getBorderClip;
}

/*
 * Manual redirected windows are treated as transparent; they do not obscure
 * siblings or parent windows
 */

#ifdef COMPOSITE
#define TreatAsTransparent(w)	((w)->redirectDraw == RedirectDrawManual)
#else
#define TreatAsTransparent(w)	FALSE
#endif

#define HasParentRelativeBorder(w) (!(w)->borderIsPixel && \
				    HasBorder(w) && \
				    (w)->backgroundState == ParentRelative)


/*
 *-----------------------------------------------------------------------
 * miComputeClips --
 *	Recompute the clipList, borderClip, exposed and borderExposed
 *	regions for pParent and its children. Only viewable windows are
 *	taken into account.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	clipList, borderClip, exposed and borderExposed are altered.
 *	A VisibilityNotify event may be generated on the parent window.
 *
 *-----------------------------------------------------------------------
 */
static void
miComputeClips (
    WindowPtr	pParent,
    ScreenPtr	pScreen,
    RegionPtr	universe,
    VTKind		kind,
    RegionPtr		exposed ) /* for intermediate calculations */
{
    int			dx,
			dy;
    RegionRec		childUniverse;
    WindowPtr		pChild;
    int     	  	oldVis, newVis;
    BoxRec		borderSize;
    RegionRec		childUnion;
    Bool		overlap;
    RegionPtr		borderVisible;
    Bool		resized;
    /*
     * Figure out the new visibility of this window.
     * The extent of the universe should be the same as the extent of
     * the borderSize region. If the window is unobscured, this rectangle
     * will be completely inside the universe (the universe will cover it
     * completely). If the window is completely obscured, none of the
     * universe will cover the rectangle.
     */
    borderSize.x1 = pParent->drawable.x - wBorderWidth(pParent);
    borderSize.y1 = pParent->drawable.y - wBorderWidth(pParent);
    dx = (int) pParent->drawable.x + (int) pParent->drawable.width + wBorderWidth(pParent);
    if (dx > 32767)
	dx = 32767;
    borderSize.x2 = dx;
    dy = (int) pParent->drawable.y + (int) pParent->drawable.height + wBorderWidth(pParent);
    if (dy > 32767)
	dy = 32767;
    borderSize.y2 = dy;

#ifdef COMPOSITE
    /*
     * In redirected drawing case, reset universe to borderSize
     */
    if (pParent->redirectDraw != RedirectDrawNone)
    {
	if (miSetRedirectBorderClipProc)
	{
	    if (TreatAsTransparent (pParent))
		REGION_EMPTY (pScreen, universe);
	    (*miSetRedirectBorderClipProc) (pParent, universe);
	}
	REGION_COPY(pScreen, universe, &pParent->borderSize);
    }
#endif

    oldVis = pParent->visibility;
    switch (RECT_IN_REGION( pScreen, universe, &borderSize)) 
    {
	case rgnIN:
	    newVis = VisibilityUnobscured;
	    break;
	case rgnPART:
	    newVis = VisibilityPartiallyObscured;
	    {
		RegionPtr   pBounding;

		if ((pBounding = wBoundingShape (pParent)))
		{
		    switch (miShapedWindowIn (pScreen, universe, pBounding,
					      &borderSize,
					      pParent->drawable.x,
 					      pParent->drawable.y))
		    {
		    case rgnIN:
			newVis = VisibilityUnobscured;
			break;
		    case rgnOUT:
			newVis = VisibilityFullyObscured;
			break;
		    }
		}
	    }
	    break;
	default:
	    newVis = VisibilityFullyObscured;
	    break;
    }
    pParent->visibility = newVis;
    if (oldVis != newVis &&
	((pParent->eventMask | wOtherEventMasks(pParent)) & VisibilityChangeMask))
	SendVisibilityNotify(pParent);

    dx = pParent->drawable.x - pParent->valdata->before.oldAbsCorner.x;
    dy = pParent->drawable.y - pParent->valdata->before.oldAbsCorner.y;

    /*
     * avoid computations when dealing with simple operations
     */

    switch (kind) {
    case VTMap:
    case VTStack:
    case VTUnmap:
	break;
    case VTMove:
	if ((oldVis == newVis) &&
	    ((oldVis == VisibilityFullyObscured) ||
	     (oldVis == VisibilityUnobscured)))
	{
	    pChild = pParent;
	    while (1)
	    {
		if (pChild->viewable)
		{
		    if (pChild->visibility != VisibilityFullyObscured)
		    {
			REGION_TRANSLATE( pScreen, &pChild->borderClip,
						      dx, dy);
			REGION_TRANSLATE( pScreen, &pChild->clipList,
						      dx, dy);
			pChild->drawable.serialNumber = NEXT_SERIAL_NUMBER;
			if (pScreen->ClipNotify)
			    (* pScreen->ClipNotify) (pChild, dx, dy);

		    }
		    if (pChild->valdata)
		    {
			REGION_NULL(pScreen,
				    &pChild->valdata->after.borderExposed);
			if (HasParentRelativeBorder(pChild))
			{
			    REGION_SUBTRACT(pScreen,
					 &pChild->valdata->after.borderExposed,
					 &pChild->borderClip,
					 &pChild->winSize);
			}
			REGION_NULL(pScreen, &pChild->valdata->after.exposed);
		    }
		    if (pChild->firstChild)
		    {
			pChild = pChild->firstChild;
			continue;
		    }
		}
		while (!pChild->nextSib && (pChild != pParent))
		    pChild = pChild->parent;
		if (pChild == pParent)
		    break;
		pChild = pChild->nextSib;
	    }
	    return;
	}
	/* fall through */
    default:
    	/*
     	 * To calculate exposures correctly, we have to translate the old
     	 * borderClip and clipList regions to the window's new location so there
     	 * is a correspondence between pieces of the new and old clipping regions.
     	 */
    	if (dx || dy) 
    	{
	    /*
	     * We translate the old clipList because that will be exposed or copied
	     * if gravity is right.
	     */
	    REGION_TRANSLATE( pScreen, &pParent->borderClip, dx, dy);
	    REGION_TRANSLATE( pScreen, &pParent->clipList, dx, dy);
    	} 
	break;
    case VTBroken:
	REGION_EMPTY (pScreen, &pParent->borderClip);
	REGION_EMPTY (pScreen, &pParent->clipList);
	break;
    }

    borderVisible = pParent->valdata->before.borderVisible;
    resized = pParent->valdata->before.resized;
    REGION_NULL(pScreen, &pParent->valdata->after.borderExposed);
    REGION_NULL(pScreen, &pParent->valdata->after.exposed);

    /*
     * Since the borderClip must not be clipped by the children, we do
     * the border exposure first...
     *
     * 'universe' is the window's borderClip. To figure the exposures, remove
     * the area that used to be exposed from the new.
     * This leaves a region of pieces that weren't exposed before.
     */

    if (HasBorder (pParent))
    {
    	if (borderVisible)
    	{
	    /*
	     * when the border changes shape, the old visible portions
	     * of the border will be saved by DIX in borderVisible --
	     * use that region and destroy it
	     */
	    REGION_SUBTRACT( pScreen, exposed, universe, borderVisible);
	    REGION_DESTROY( pScreen, borderVisible);
    	}
    	else
    	{
	    REGION_SUBTRACT( pScreen, exposed, universe, &pParent->borderClip);
    	}
	if (HasParentRelativeBorder(pParent) && (dx || dy))
	    REGION_SUBTRACT( pScreen, &pParent->valdata->after.borderExposed,
				  universe,
				  &pParent->winSize);
	else
	    REGION_SUBTRACT( pScreen, &pParent->valdata->after.borderExposed,
			       exposed, &pParent->winSize);

    	REGION_COPY( pScreen, &pParent->borderClip, universe);
    
    	/*
     	 * To get the right clipList for the parent, and to make doubly sure
     	 * that no child overlaps the parent's border, we remove the parent's
     	 * border from the universe before proceeding.
     	 */
    
    	REGION_INTERSECT( pScreen, universe, universe, &pParent->winSize);
    }
    else
    	REGION_COPY( pScreen, &pParent->borderClip, universe);
    
    if ((pChild = pParent->firstChild) && pParent->mapped)
    {
	REGION_NULL(pScreen, &childUniverse);
	REGION_NULL(pScreen, &childUnion);
	if ((pChild->drawable.y < pParent->lastChild->drawable.y) ||
	    ((pChild->drawable.y == pParent->lastChild->drawable.y) &&
	     (pChild->drawable.x < pParent->lastChild->drawable.x)))
	{
	    for (; pChild; pChild = pChild->nextSib)
	    {
		if (pChild->viewable && !TreatAsTransparent(pChild))
		    REGION_APPEND( pScreen, &childUnion, &pChild->borderSize);
	    }
	}
	else
	{
	    for (pChild = pParent->lastChild; pChild; pChild = pChild->prevSib)
	    {
		if (pChild->viewable && !TreatAsTransparent(pChild))
		    REGION_APPEND( pScreen, &childUnion, &pChild->borderSize);
	    }
	}
	REGION_VALIDATE( pScreen, &childUnion, &overlap);

	for (pChild = pParent->firstChild;
	     pChild;
	     pChild = pChild->nextSib)
 	{
	    if (pChild->viewable) {
		/*
		 * If the child is viewable, we want to remove its extents
		 * from the current universe, but we only re-clip it if
		 * it's been marked.
		 */
		if (pChild->valdata) {
		    /*
		     * Figure out the new universe from the child's
		     * perspective and recurse.
		     */
		    REGION_INTERSECT( pScreen, &childUniverse,
					    universe,
					    &pChild->borderSize);
		    miComputeClips (pChild, pScreen, &childUniverse, kind,
				    exposed);
		}
		/*
		 * Once the child has been processed, we remove its extents
		 * from the current universe, thus denying its space to any
		 * other sibling.
		 */
		if (overlap && !TreatAsTransparent (pChild))
		    REGION_SUBTRACT( pScreen, universe, universe,
					  &pChild->borderSize);
	    }
	}
	if (!overlap)
	    REGION_SUBTRACT( pScreen, universe, universe, &childUnion);
	REGION_UNINIT( pScreen, &childUnion);
	REGION_UNINIT( pScreen, &childUniverse);
    } /* if any children */

    /*
     * 'universe' now contains the new clipList for the parent window.
     *
     * To figure the exposure of the window we subtract the old clip from the
     * new, just as for the border.
     */

    if (oldVis == VisibilityFullyObscured ||
	oldVis == VisibilityNotViewable)
    {
	REGION_COPY( pScreen, &pParent->valdata->after.exposed, universe);
    }
    else if (newVis != VisibilityFullyObscured &&
	     newVis != VisibilityNotViewable)
    {
    	REGION_SUBTRACT( pScreen, &pParent->valdata->after.exposed,
			       universe, &pParent->clipList);
    }

    /* HACK ALERT - copying contents of regions, instead of regions */
    {
	RegionRec   tmp;

	tmp = pParent->clipList;
	pParent->clipList = *universe;
	*universe = tmp;
    }

#ifdef NOTDEF
    REGION_COPY( pScreen, &pParent->clipList, universe);
#endif

    pParent->drawable.serialNumber = NEXT_SERIAL_NUMBER;

    if (pScreen->ClipNotify)
	(* pScreen->ClipNotify) (pParent, dx, dy);
}

static void
miTreeObscured(
    WindowPtr pParent )
{
    WindowPtr 	pChild;
    int    	oldVis;

    pChild = pParent;
    while (1)
    {
	if (pChild->viewable)
	{
	    oldVis = pChild->visibility;
	    if (oldVis != (pChild->visibility = VisibilityFullyObscured) &&
		((pChild->eventMask | wOtherEventMasks(pChild)) & VisibilityChangeMask))
		SendVisibilityNotify(pChild);
	    if (pChild->firstChild)
	    {
		pChild = pChild->firstChild;
		continue;
	    }
	}
	while (!pChild->nextSib && (pChild != pParent))
	    pChild = pChild->parent;
	if (pChild == pParent)
	    break;
	pChild = pChild->nextSib;
    }
}

/*
 *-----------------------------------------------------------------------
 * miValidateTree --
 *	Recomputes the clip list for pParent and all its inferiors.
 *
 * Results:
 *	Always returns 1.
 *
 * Side Effects:
 *	The clipList, borderClip, exposed, and borderExposed regions for
 *	each marked window are altered.
 *
 * Notes:
 *	This routine assumes that all affected windows have been marked
 *	(valdata created) and their winSize and borderSize regions
 *	adjusted to correspond to their new positions. The borderClip and
 *	clipList regions should not have been touched.
 *
 *	The top-most level is treated differently from all lower levels
 *	because pParent is unchanged. For the top level, we merge the
 *	regions taken up by the marked children back into the clipList
 *	for pParent, thus forming a region from which the marked children
 *	can claim their areas. For lower levels, where the old clipList
 *	and borderClip are invalid, we can't do this and have to do the
 *	extra operations done in miComputeClips, but this is much faster
 *	e.g. when only one child has moved...
 *
 *-----------------------------------------------------------------------
 */
/*ARGSUSED*/
int
miValidateTree (
    WindowPtr		pParent,    /* Parent to validate */
    WindowPtr		pChild,     /* First child of pParent that was
				     * affected */
    VTKind		kind        /* What kind of configuration caused call */
    )
{
    RegionRec	  	totalClip;  /* Total clipping region available to
				     * the marked children. pParent's clipList
				     * merged with the borderClips of all
				     * the marked children. */
    RegionRec	  	childClip;  /* The new borderClip for the current
				     * child */
    RegionRec		childUnion; /* the space covered by borderSize for
				     * all marked children */
    RegionRec		exposed;    /* For intermediate calculations */
    ScreenPtr		pScreen;
    WindowPtr		pWin;
    Bool		overlap;
    int			viewvals;
    Bool		forward;

    pScreen = pParent->drawable.pScreen;
    if (pChild == NullWindow)
	pChild = pParent->firstChild;

    REGION_NULL(pScreen, &childClip);
    REGION_NULL(pScreen, &exposed);

    /*
     * compute the area of the parent window occupied
     * by the marked children + the parent itself.  This
     * is the area which can be divied up among the marked
     * children in their new configuration.
     */
    REGION_NULL(pScreen, &totalClip);
    viewvals = 0;
    if (REGION_BROKEN (pScreen, &pParent->clipList) &&
	!REGION_BROKEN (pScreen, &pParent->borderClip))
    {
	kind = VTBroken;
	/*
	 * When rebuilding clip lists after out of memory,
	 * assume everything is busted.
	 */
	forward = TRUE;
	REGION_COPY (pScreen, &totalClip, &pParent->borderClip);
	REGION_INTERSECT (pScreen, &totalClip, &totalClip, &pParent->winSize);
	
	for (pWin = pParent->firstChild; pWin != pChild; pWin = pWin->nextSib)
	{
	    if (pWin->viewable && !TreatAsTransparent (pWin))
		REGION_SUBTRACT (pScreen, &totalClip, &totalClip, &pWin->borderSize);
	}
	for (pWin = pChild; pWin; pWin = pWin->nextSib)
	    if (pWin->valdata && pWin->viewable)
		viewvals++;
	
	REGION_EMPTY (pScreen, &pParent->clipList);
    }
    else 
    {
	if ((pChild->drawable.y < pParent->lastChild->drawable.y) ||
	    ((pChild->drawable.y == pParent->lastChild->drawable.y) &&
	     (pChild->drawable.x < pParent->lastChild->drawable.x)))
	{
	    forward = TRUE;
	    for (pWin = pChild; pWin; pWin = pWin->nextSib)
	    {
		if (pWin->valdata)
		{
		    RegionPtr	pBorderClip = &pWin->borderClip;
#ifdef COMPOSITE
		    if (pWin->redirectDraw != RedirectDrawNone && miGetRedirectBorderClipProc)
			pBorderClip = (*miGetRedirectBorderClipProc)(pWin);
#endif
		    REGION_APPEND( pScreen, &totalClip, pBorderClip );
		    if (pWin->viewable)
			viewvals++;
		}
	    }
	}
	else
	{
	    forward = FALSE;
	    pWin = pParent->lastChild;
	    while (1)
	    {
		if (pWin->valdata)
		{
		    RegionPtr	pBorderClip = &pWin->borderClip;
#ifdef COMPOSITE
		    if (pWin->redirectDraw != RedirectDrawNone && miGetRedirectBorderClipProc)
			pBorderClip = (*miGetRedirectBorderClipProc)(pWin);
#endif
		    REGION_APPEND( pScreen, &totalClip, pBorderClip );
		    if (pWin->viewable)
			viewvals++;
		}
		if (pWin == pChild)
		    break;
		pWin = pWin->prevSib;
	    }
	}
	REGION_VALIDATE( pScreen, &totalClip, &overlap);
    }

    /*
     * Now go through the children of the root and figure their new
     * borderClips from the totalClip, passing that off to miComputeClips
     * to handle recursively. Once that's done, we remove the child
     * from the totalClip to clip any siblings below it.
     */

    overlap = TRUE;
    if (kind != VTStack)
    {
	REGION_UNION( pScreen, &totalClip, &totalClip, &pParent->clipList);
	if (viewvals > 1)
	{
	    /*
	     * precompute childUnion to discover whether any of them
	     * overlap.  This seems redundant, but performance studies
	     * have demonstrated that the cost of this loop is
	     * lower than the cost of multiple Subtracts in the
	     * loop below.
	     */
	    REGION_NULL(pScreen, &childUnion);
	    if (forward)
	    {
		for (pWin = pChild; pWin; pWin = pWin->nextSib)
		    if (pWin->valdata && pWin->viewable && !TreatAsTransparent (pWin))
			REGION_APPEND( pScreen, &childUnion,
						   &pWin->borderSize);
	    }
	    else
	    {
		pWin = pParent->lastChild;
		while (1)
		{
		    if (pWin->valdata && pWin->viewable && !TreatAsTransparent (pWin))
			REGION_APPEND( pScreen, &childUnion,
						   &pWin->borderSize);
		    if (pWin == pChild)
			break;
		    pWin = pWin->prevSib;
		}
	    }
	    REGION_VALIDATE(pScreen, &childUnion, &overlap);
	    if (overlap)
		REGION_UNINIT(pScreen, &childUnion);
	}
    }

    for (pWin = pChild;
	 pWin != NullWindow;
	 pWin = pWin->nextSib)
    {
	if (pWin->viewable) {
	    if (pWin->valdata) {
		REGION_INTERSECT( pScreen, &childClip,
					&totalClip,
 					&pWin->borderSize);
		miComputeClips (pWin, pScreen, &childClip, kind, &exposed);
		if (overlap && !TreatAsTransparent (pWin))
		{
		    REGION_SUBTRACT( pScreen, &totalClip,
				       	   &totalClip,
				       	   &pWin->borderSize);
		}
	    } else if (pWin->visibility == VisibilityNotViewable) {
		miTreeObscured(pWin);
	    }
	} else {
	    if (pWin->valdata) {
		REGION_EMPTY( pScreen, &pWin->clipList);
		if (pScreen->ClipNotify)
		    (* pScreen->ClipNotify) (pWin, 0, 0);
		REGION_EMPTY( pScreen, &pWin->borderClip);
		pWin->valdata = (ValidatePtr)NULL;
	    }
	}
    }

    REGION_UNINIT( pScreen, &childClip);
    if (!overlap)
    {
	REGION_SUBTRACT(pScreen, &totalClip, &totalClip, &childUnion);
	REGION_UNINIT(pScreen, &childUnion);
    }

    REGION_NULL(pScreen, &pParent->valdata->after.exposed);
    REGION_NULL(pScreen, &pParent->valdata->after.borderExposed);

    /*
     * each case below is responsible for updating the
     * clipList and serial number for the parent window
     */

    switch (kind) {
    case VTStack:
	break;
    default:
	/*
	 * totalClip contains the new clipList for the parent. Figure out
	 * exposures and obscures as per miComputeClips and reset the parent's
	 * clipList.
	 */
	REGION_SUBTRACT( pScreen, &pParent->valdata->after.exposed,
			       &totalClip, &pParent->clipList);
	/* fall through */
    case VTMap:
	REGION_COPY( pScreen, &pParent->clipList, &totalClip);
	pParent->drawable.serialNumber = NEXT_SERIAL_NUMBER;
	break;
    }

    REGION_UNINIT( pScreen, &totalClip);
    REGION_UNINIT( pScreen, &exposed);
    if (pScreen->ClipNotify)
	(*pScreen->ClipNotify) (pParent, 0, 0);
    return (1);
}