1 /* $TOG: Region.c /main/31 1998/02/06 17:50:22 kaleb $ */
2 /************************************************************************
4 Copyright 1987, 1988, 1998 The Open Group
8 The above copyright notice and this permission notice shall be included in
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23 Copyright 1987, 1988 by Digital Equipment Corporation, Maynard, Massachusetts.
27 Permission to use, copy, modify, and distribute this software and its
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43 ************************************************************************/
44 /* $XFree86: xc/lib/X11/Region.c,v 1.5 1999/05/09 10:50:01 dawes Exp $ */
46 * The functions in this file implement the Region abstraction, similar to one
47 * used in the X11 sample server. A Region is simply an area, as the name
48 * implies, and is implemented as a "y-x-banded" array of rectangles. To
49 * explain: Each Region is made up of a certain number of rectangles sorted
50 * by y coordinate first, and then by x coordinate.
52 * Furthermore, the rectangles are banded such that every rectangle with a
53 * given upper-left y coordinate (y1) will have the same lower-right y
54 * coordinate (y2) and vice versa. If a rectangle has scanlines in a band, it
55 * will span the entire vertical distance of the band. This means that some
56 * areas that could be merged into a taller rectangle will be represented as
57 * several shorter rectangles to account for shorter rectangles to its left
58 * or right but within its "vertical scope".
60 * An added constraint on the rectangles is that they must cover as much
61 * horizontal area as possible. E.g. no two rectangles in a band are allowed
64 * Whenever possible, bands will be merged together to cover a greater vertical
65 * distance (and thus reduce the number of rectangles). Two bands can be merged
66 * only if the bottom of one touches the top of the other and they have
67 * rectangles in the same places (of the same width, of course). This maintains
68 * the y-x-banding that's so nice to have...
73 #include <gdkregion.h>
74 #include "gdkregion-generic.h"
78 #define assert(expr) {if (!(expr)) fprintf(stderr,\
79 "Assertion failed file %s, line %d: expr\n", __FILE__, __LINE__); }
84 typedef void (*overlapFunc) (GdkRegion *pReg,
91 typedef void (*nonOverlapFunc) (GdkRegion *pReg,
97 static void miRegionCopy (GdkRegion *dstrgn,
99 static void miRegionOp (GdkRegion *newReg,
102 overlapFunc overlapFn,
103 nonOverlapFunc nonOverlap1Fn,
104 nonOverlapFunc nonOverlap2Fn);
106 /* Create a new empty region */
113 temp = g_new (GdkRegion, 1);
114 temp->rects = g_new (GdkRegionBox, 1);
117 temp->extents.x1 = 0;
118 temp->extents.y1 = 0;
119 temp->extents.x2 = 0;
120 temp->extents.y2 = 0;
127 gdk_region_rectangle (GdkRectangle *rectangle)
131 if (rectangle->width <= 0 || rectangle->height <= 0)
132 return gdk_region_new();
134 temp = g_new (GdkRegion, 1);
135 temp->rects = g_new (GdkRegionBox, 1);
138 temp->extents.x1 = temp->rects[0].x1 = rectangle->x;
139 temp->extents.y1 = temp->rects[0].y1 = rectangle->y;
140 temp->extents.x2 = temp->rects[0].x2 = rectangle->x + rectangle->width;
141 temp->extents.y2 = temp->rects[0].y2 = rectangle->y + rectangle->height;
148 gdk_region_copy (GdkRegion *region)
152 temp = g_new (GdkRegion, 1);
153 temp->rects = g_new (GdkRegionBox, region->numRects);
155 temp->numRects = region->numRects;
156 temp->extents = region->extents;
157 temp->size = region->numRects;
159 memcpy (temp->rects, region->rects, region->numRects * sizeof (GdkRegionBox));
165 gdk_region_get_clipbox (GdkRegion *r, GdkRectangle *rect)
167 rect->x = r->extents.x1;
168 rect->y = r->extents.y1;
169 rect->width = r->extents.x2 - r->extents.x1;
170 rect->height = r->extents.y2 - r->extents.y1;
174 gdk_region_union_with_rect (GdkRegion *region,
177 GdkRegion tmp_region;
179 if (!rect->width || !rect->height)
182 tmp_region.rects = &tmp_region.extents;
183 tmp_region.numRects = 1;
184 tmp_region.extents.x1 = rect->x;
185 tmp_region.extents.y1 = rect->y;
186 tmp_region.extents.x2 = rect->x + rect->width;
187 tmp_region.extents.y2 = rect->y + rect->height;
190 gdk_region_union (region, &tmp_region);
194 *-----------------------------------------------------------------------
196 * Reset the extents of a region to what they should be. Called by
197 * miSubtract and miIntersect b/c they can't figure it out along the
198 * way or do so easily, as miUnion can.
204 * The region's 'extents' structure is overwritten.
206 *-----------------------------------------------------------------------
209 miSetExtents (GdkRegion *pReg)
211 GdkRegionBox *pBox, *pBoxEnd, *pExtents;
213 if (pReg->numRects == 0)
215 pReg->extents.x1 = 0;
216 pReg->extents.y1 = 0;
217 pReg->extents.x2 = 0;
218 pReg->extents.y2 = 0;
222 pExtents = &pReg->extents;
224 pBoxEnd = &pBox[pReg->numRects - 1];
227 * Since pBox is the first rectangle in the region, it must have the
228 * smallest y1 and since pBoxEnd is the last rectangle in the region,
229 * it must have the largest y2, because of banding. Initialize x1 and
230 * x2 from pBox and pBoxEnd, resp., as good things to initialize them
233 pExtents->x1 = pBox->x1;
234 pExtents->y1 = pBox->y1;
235 pExtents->x2 = pBoxEnd->x2;
236 pExtents->y2 = pBoxEnd->y2;
238 assert(pExtents->y1 < pExtents->y2);
239 while (pBox <= pBoxEnd)
241 if (pBox->x1 < pExtents->x1)
243 pExtents->x1 = pBox->x1;
245 if (pBox->x2 > pExtents->x2)
247 pExtents->x2 = pBox->x2;
251 assert(pExtents->x1 < pExtents->x2);
255 gdk_region_destroy (GdkRegion *r)
262 /* TranslateRegion(pRegion, x, y)
268 gdk_region_offset (GdkRegion *region,
275 pbox = region->rects;
276 nbox = region->numRects;
286 region->extents.x1 += x;
287 region->extents.x2 += x;
288 region->extents.y1 += y;
289 region->extents.y2 += y;
293 Utility procedure Compress:
294 Replace r by the region r', where
295 p in r' iff (Quantifer m <= dx) (p + m in r), and
296 Quantifier is Exists if grow is TRUE, For all if grow is FALSE, and
297 (x,y) + m = (x+m,y) if xdir is TRUE; (x,y+m) if xdir is FALSE.
299 Thus, if xdir is TRUE and grow is FALSE, r is replaced by the region
300 of all points p such that p and the next dx points on the same
301 horizontal scan line are all in r. We do this using by noting
302 that p is the head of a run of length 2^i + k iff p is the head
303 of a run of length 2^i and p+2^i is the head of a run of length
304 k. Thus, the loop invariant: s contains the region corresponding
305 to the runs of length shift. r contains the region corresponding
306 to the runs of length 1 + dxo & (shift-1), where dxo is the original
307 value of dx. dx = dxo & ~(shift-1). As parameters, s and t are
308 scratch regions, so that we don't have to allocate them on every
312 #define ZOpRegion(a,b) if (grow) gdk_region_union (a, b); \
313 else gdk_region_intersect (a,b)
314 #define ZShiftRegion(a,b) if (xdir) gdk_region_offset (a,b,0); \
315 else gdk_region_offset (a,0,b)
318 Compress(GdkRegion *r,
332 ZShiftRegion(r, -(int)shift);
338 ZShiftRegion(s, -(int)shift);
349 gdk_region_shrink (GdkRegion *r,
359 s = gdk_region_new ();
360 t = gdk_region_new ();
366 Compress(r, s, t, (unsigned) 2*dx, TRUE, grow);
372 Compress(r, s, t, (unsigned) 2*dy, FALSE, grow);
374 gdk_region_offset (r, dx, dy);
375 gdk_region_destroy (s);
376 gdk_region_destroy (t);
380 /*======================================================================
381 * Region Intersection
382 *====================================================================*/
384 *-----------------------------------------------------------------------
386 * Handle an overlapping band for miIntersect.
392 * Rectangles may be added to the region.
394 *-----------------------------------------------------------------------
398 miIntersectO (GdkRegion *pReg,
408 GdkRegionBox *pNextRect;
410 pNextRect = &pReg->rects[pReg->numRects];
412 while ((r1 != r1End) && (r2 != r2End))
414 x1 = MAX (r1->x1,r2->x1);
415 x2 = MIN (r1->x2,r2->x2);
418 * If there's any overlap between the two rectangles, add that
419 * overlap to the new region.
420 * There's no need to check for subsumption because the only way
421 * such a need could arise is if some region has two rectangles
422 * right next to each other. Since that should never happen...
428 MEMCHECK (pReg, pNextRect, pReg->rects);
435 assert (pReg->numRects <= pReg->size);
439 * Need to advance the pointers. Shift the one that extends
440 * to the right the least, since the other still has a chance to
441 * overlap with that region's next rectangle, if you see what I mean.
447 else if (r2->x2 < r1->x2)
460 gdk_region_intersect (GdkRegion *region,
463 /* check for trivial reject */
464 if ((!(region->numRects)) || (!(other->numRects)) ||
465 (!EXTENTCHECK(®ion->extents, &other->extents)))
466 region->numRects = 0;
468 miRegionOp (region, region, other,
469 miIntersectO, (nonOverlapFunc) NULL, (nonOverlapFunc) NULL);
472 * Can't alter region's extents before miRegionOp depends on the
473 * extents of the regions being unchanged. Besides, this way there's
474 * no checking against rectangles that will be nuked due to
475 * coalescing, so we have to examine fewer rectangles.
477 miSetExtents(region);
481 miRegionCopy(GdkRegion *dstrgn, GdkRegion *rgn)
483 if (dstrgn != rgn) /* don't want to copy to itself */
485 if (dstrgn->size < rgn->numRects)
487 dstrgn->rects = g_renew (GdkRegionBox, dstrgn->rects, rgn->numRects);
488 dstrgn->size = rgn->numRects;
490 dstrgn->numRects = rgn->numRects;
491 dstrgn->extents.x1 = rgn->extents.x1;
492 dstrgn->extents.y1 = rgn->extents.y1;
493 dstrgn->extents.x2 = rgn->extents.x2;
494 dstrgn->extents.y2 = rgn->extents.y2;
496 memcpy (dstrgn->rects, rgn->rects, rgn->numRects * sizeof (GdkRegionBox));
501 /*======================================================================
502 * Generic Region Operator
503 *====================================================================*/
506 *-----------------------------------------------------------------------
508 * Attempt to merge the boxes in the current band with those in the
509 * previous one. Used only by miRegionOp.
512 * The new index for the previous band.
515 * If coalescing takes place:
516 * - rectangles in the previous band will have their y2 fields
518 * - pReg->numRects will be decreased.
520 *-----------------------------------------------------------------------
524 miCoalesce (GdkRegion *pReg, /* Region to coalesce */
525 gint prevStart, /* Index of start of previous band */
526 gint curStart) /* Index of start of current band */
528 GdkRegionBox *pPrevBox; /* Current box in previous band */
529 GdkRegionBox *pCurBox; /* Current box in current band */
530 GdkRegionBox *pRegEnd; /* End of region */
531 int curNumRects; /* Number of rectangles in current
533 int prevNumRects; /* Number of rectangles in previous
535 int bandY1; /* Y1 coordinate for current band */
537 pRegEnd = &pReg->rects[pReg->numRects];
539 pPrevBox = &pReg->rects[prevStart];
540 prevNumRects = curStart - prevStart;
543 * Figure out how many rectangles are in the current band. Have to do
544 * this because multiple bands could have been added in miRegionOp
545 * at the end when one region has been exhausted.
547 pCurBox = &pReg->rects[curStart];
548 bandY1 = pCurBox->y1;
549 for (curNumRects = 0;
550 (pCurBox != pRegEnd) && (pCurBox->y1 == bandY1);
556 if (pCurBox != pRegEnd)
559 * If more than one band was added, we have to find the start
560 * of the last band added so the next coalescing job can start
561 * at the right place... (given when multiple bands are added,
562 * this may be pointless -- see above).
565 while (pRegEnd[-1].y1 == pRegEnd->y1)
569 curStart = pRegEnd - pReg->rects;
570 pRegEnd = pReg->rects + pReg->numRects;
573 if ((curNumRects == prevNumRects) && (curNumRects != 0)) {
574 pCurBox -= curNumRects;
576 * The bands may only be coalesced if the bottom of the previous
577 * matches the top scanline of the current.
579 if (pPrevBox->y2 == pCurBox->y1)
582 * Make sure the bands have boxes in the same places. This
583 * assumes that boxes have been added in such a way that they
584 * cover the most area possible. I.e. two boxes in a band must
585 * have some horizontal space between them.
589 if ((pPrevBox->x1 != pCurBox->x1) ||
590 (pPrevBox->x2 != pCurBox->x2))
593 * The bands don't line up so they can't be coalesced.
600 } while (prevNumRects != 0);
602 pReg->numRects -= curNumRects;
603 pCurBox -= curNumRects;
604 pPrevBox -= curNumRects;
607 * The bands may be merged, so set the bottom y of each box
608 * in the previous band to that of the corresponding box in
613 pPrevBox->y2 = pCurBox->y2;
618 while (curNumRects != 0);
621 * If only one band was added to the region, we have to backup
622 * curStart to the start of the previous band.
624 * If more than one band was added to the region, copy the
625 * other bands down. The assumption here is that the other bands
626 * came from the same region as the current one and no further
627 * coalescing can be done on them since it's all been done
628 * already... curStart is already in the right place.
630 if (pCurBox == pRegEnd)
632 curStart = prevStart;
638 *pPrevBox++ = *pCurBox++;
640 while (pCurBox != pRegEnd);
649 *-----------------------------------------------------------------------
651 * Apply an operation to two regions. Called by miUnion, miInverse,
652 * miSubtract, miIntersect...
658 * The new region is overwritten.
661 * The idea behind this function is to view the two regions as sets.
662 * Together they cover a rectangle of area that this function divides
663 * into horizontal bands where points are covered only by one region
664 * or by both. For the first case, the nonOverlapFunc is called with
665 * each the band and the band's upper and lower extents. For the
666 * second, the overlapFunc is called to process the entire band. It
667 * is responsible for clipping the rectangles in the band, though
668 * this function provides the boundaries.
669 * At the end of each band, the new region is coalesced, if possible,
670 * to reduce the number of rectangles in the region.
672 *-----------------------------------------------------------------------
676 miRegionOp(GdkRegion *newReg,
679 overlapFunc overlapFn, /* Function to call for over-
681 nonOverlapFunc nonOverlap1Fn, /* Function to call for non-
682 * overlapping bands in region
684 nonOverlapFunc nonOverlap2Fn) /* Function to call for non-
685 * overlapping bands in region
688 GdkRegionBox *r1; /* Pointer into first region */
689 GdkRegionBox *r2; /* Pointer into 2d region */
690 GdkRegionBox *r1End; /* End of 1st region */
691 GdkRegionBox *r2End; /* End of 2d region */
692 int ybot; /* Bottom of intersection */
693 int ytop; /* Top of intersection */
694 GdkRegionBox *oldRects; /* Old rects for newReg */
695 int prevBand; /* Index of start of
696 * previous band in newReg */
697 int curBand; /* Index of start of current
699 GdkRegionBox *r1BandEnd; /* End of current band in r1 */
700 GdkRegionBox *r2BandEnd; /* End of current band in r2 */
701 int top; /* Top of non-overlapping
703 int bot; /* Bottom of non-overlapping
708 * set r1, r2, r1End and r2End appropriately, preserve the important
709 * parts of the destination region until the end in case it's one of
710 * the two source regions, then mark the "new" region empty, allocating
711 * another array of rectangles for it to use.
715 r1End = r1 + reg1->numRects;
716 r2End = r2 + reg2->numRects;
718 oldRects = newReg->rects;
720 EMPTY_REGION(newReg);
723 * Allocate a reasonable number of rectangles for the new region. The idea
724 * is to allocate enough so the individual functions don't need to
725 * reallocate and copy the array, which is time consuming, yet we don't
726 * have to worry about using too much memory. I hope to be able to
727 * nuke the Xrealloc() at the end of this function eventually.
729 newReg->size = MAX (reg1->numRects, reg2->numRects) * 2;
730 newReg->rects = g_new (GdkRegionBox, newReg->size);
733 * Initialize ybot and ytop.
734 * In the upcoming loop, ybot and ytop serve different functions depending
735 * on whether the band being handled is an overlapping or non-overlapping
737 * In the case of a non-overlapping band (only one of the regions
738 * has points in the band), ybot is the bottom of the most recent
739 * intersection and thus clips the top of the rectangles in that band.
740 * ytop is the top of the next intersection between the two regions and
741 * serves to clip the bottom of the rectangles in the current band.
742 * For an overlapping band (where the two regions intersect), ytop clips
743 * the top of the rectangles of both regions and ybot clips the bottoms.
745 if (reg1->extents.y1 < reg2->extents.y1)
746 ybot = reg1->extents.y1;
748 ybot = reg2->extents.y1;
751 * prevBand serves to mark the start of the previous band so rectangles
752 * can be coalesced into larger rectangles. qv. miCoalesce, above.
753 * In the beginning, there is no previous band, so prevBand == curBand
754 * (curBand is set later on, of course, but the first band will always
755 * start at index 0). prevBand and curBand must be indices because of
756 * the possible expansion, and resultant moving, of the new region's
757 * array of rectangles.
763 curBand = newReg->numRects;
766 * This algorithm proceeds one source-band (as opposed to a
767 * destination band, which is determined by where the two regions
768 * intersect) at a time. r1BandEnd and r2BandEnd serve to mark the
769 * rectangle after the last one in the current band for their
770 * respective regions.
773 while ((r1BandEnd != r1End) && (r1BandEnd->y1 == r1->y1))
779 while ((r2BandEnd != r2End) && (r2BandEnd->y1 == r2->y1))
785 * First handle the band that doesn't intersect, if any.
787 * Note that attention is restricted to one band in the
788 * non-intersecting region at once, so if a region has n
789 * bands between the current position and the next place it overlaps
790 * the other, this entire loop will be passed through n times.
794 top = MAX (r1->y1,ybot);
795 bot = MIN (r1->y2,r2->y1);
797 if ((top != bot) && (nonOverlap1Fn != (void (*)())NULL))
799 (* nonOverlap1Fn) (newReg, r1, r1BandEnd, top, bot);
804 else if (r2->y1 < r1->y1)
806 top = MAX (r2->y1,ybot);
807 bot = MIN (r2->y2,r1->y1);
809 if ((top != bot) && (nonOverlap2Fn != (void (*)())NULL))
811 (* nonOverlap2Fn) (newReg, r2, r2BandEnd, top, bot);
822 * If any rectangles got added to the region, try and coalesce them
823 * with rectangles from the previous band. Note we could just do
824 * this test in miCoalesce, but some machines incur a not
825 * inconsiderable cost for function calls, so...
827 if (newReg->numRects != curBand)
829 prevBand = miCoalesce (newReg, prevBand, curBand);
833 * Now see if we've hit an intersecting band. The two bands only
834 * intersect if ybot > ytop
836 ybot = MIN (r1->y2, r2->y2);
837 curBand = newReg->numRects;
840 (* overlapFn) (newReg, r1, r1BandEnd, r2, r2BandEnd, ytop, ybot);
844 if (newReg->numRects != curBand)
846 prevBand = miCoalesce (newReg, prevBand, curBand);
850 * If we've finished with a band (y2 == ybot) we skip forward
851 * in the region to the next band.
861 } while ((r1 != r1End) && (r2 != r2End));
864 * Deal with whichever region still has rectangles left.
866 curBand = newReg->numRects;
869 if (nonOverlap1Fn != (nonOverlapFunc )NULL)
874 while ((r1BandEnd < r1End) && (r1BandEnd->y1 == r1->y1))
878 (* nonOverlap1Fn) (newReg, r1, r1BandEnd,
879 MAX (r1->y1,ybot), r1->y2);
881 } while (r1 != r1End);
884 else if ((r2 != r2End) && (nonOverlap2Fn != (nonOverlapFunc) NULL))
889 while ((r2BandEnd < r2End) && (r2BandEnd->y1 == r2->y1))
893 (* nonOverlap2Fn) (newReg, r2, r2BandEnd,
894 MAX (r2->y1,ybot), r2->y2);
896 } while (r2 != r2End);
899 if (newReg->numRects != curBand)
901 (void) miCoalesce (newReg, prevBand, curBand);
905 * A bit of cleanup. To keep regions from growing without bound,
906 * we shrink the array of rectangles to match the new number of
907 * rectangles in the region. This never goes to 0, however...
909 * Only do this stuff if the number of rectangles allocated is more than
910 * twice the number of rectangles in the region (a simple optimization...).
912 if (newReg->numRects < (newReg->size >> 1))
914 if (REGION_NOT_EMPTY (newReg))
916 newReg->size = newReg->numRects;
917 newReg->rects = g_renew (GdkRegionBox, newReg->rects, newReg->size);
922 * No point in doing the extra work involved in an Xrealloc if
923 * the region is empty
926 g_free (newReg->rects);
927 newReg->rects = g_new (GdkRegionBox, 1);
934 /*======================================================================
936 *====================================================================*/
939 *-----------------------------------------------------------------------
941 * Handle a non-overlapping band for the union operation. Just
942 * Adds the rectangles into the region. Doesn't have to check for
943 * subsumption or anything.
949 * pReg->numRects is incremented and the final rectangles overwritten
950 * with the rectangles we're passed.
952 *-----------------------------------------------------------------------
955 miUnionNonO (GdkRegion *pReg,
961 GdkRegionBox *pNextRect;
963 pNextRect = &pReg->rects[pReg->numRects];
969 assert(r->x1 < r->x2);
970 MEMCHECK(pReg, pNextRect, pReg->rects);
971 pNextRect->x1 = r->x1;
973 pNextRect->x2 = r->x2;
978 assert(pReg->numRects<=pReg->size);
985 *-----------------------------------------------------------------------
987 * Handle an overlapping band for the union operation. Picks the
988 * left-most rectangle each time and merges it into the region.
994 * Rectangles are overwritten in pReg->rects and pReg->numRects will
997 *-----------------------------------------------------------------------
1002 miUnionO (GdkRegion *pReg,
1004 GdkRegionBox *r1End,
1006 GdkRegionBox *r2End,
1010 GdkRegionBox * pNextRect;
1012 pNextRect = &pReg->rects[pReg->numRects];
1014 #define MERGERECT(r) \
1015 if ((pReg->numRects != 0) && \
1016 (pNextRect[-1].y1 == y1) && \
1017 (pNextRect[-1].y2 == y2) && \
1018 (pNextRect[-1].x2 >= r->x1)) \
1020 if (pNextRect[-1].x2 < r->x2) \
1022 pNextRect[-1].x2 = r->x2; \
1023 assert(pNextRect[-1].x1<pNextRect[-1].x2); \
1028 MEMCHECK(pReg, pNextRect, pReg->rects); \
1029 pNextRect->y1 = y1; \
1030 pNextRect->y2 = y2; \
1031 pNextRect->x1 = r->x1; \
1032 pNextRect->x2 = r->x2; \
1033 pReg->numRects += 1; \
1036 assert(pReg->numRects<=pReg->size); \
1040 while ((r1 != r1End) && (r2 != r2End))
1042 if (r1->x1 < r2->x1)
1057 } while (r1 != r1End);
1059 else while (r2 != r2End)
1066 gdk_region_union (GdkRegion *region,
1069 /* checks all the simple cases */
1072 * region and other are the same or other is empty
1074 if ((region == other) || (!(other->numRects)))
1080 if (!(region->numRects))
1082 miRegionCopy (region, other);
1087 * region completely subsumes otehr
1089 if ((region->numRects == 1) &&
1090 (region->extents.x1 <= other->extents.x1) &&
1091 (region->extents.y1 <= other->extents.y1) &&
1092 (region->extents.x2 >= other->extents.x2) &&
1093 (region->extents.y2 >= other->extents.y2))
1097 * other completely subsumes region
1099 if ((other->numRects == 1) &&
1100 (other->extents.x1 <= region->extents.x1) &&
1101 (other->extents.y1 <= region->extents.y1) &&
1102 (other->extents.x2 >= region->extents.x2) &&
1103 (other->extents.y2 >= region->extents.y2))
1105 miRegionCopy(region, other);
1109 miRegionOp (region, region, other, miUnionO,
1110 miUnionNonO, miUnionNonO);
1112 region->extents.x1 = MIN (region->extents.x1, other->extents.x1);
1113 region->extents.y1 = MIN (region->extents.y1, other->extents.y1);
1114 region->extents.x2 = MAX (region->extents.x2, other->extents.x2);
1115 region->extents.y2 = MAX (region->extents.y2, other->extents.y2);
1119 /*======================================================================
1120 * Region Subtraction
1121 *====================================================================*/
1124 *-----------------------------------------------------------------------
1126 * Deal with non-overlapping band for subtraction. Any parts from
1127 * region 2 we discard. Anything from region 1 we add to the region.
1133 * pReg may be affected.
1135 *-----------------------------------------------------------------------
1139 miSubtractNonO1 (GdkRegion *pReg,
1145 GdkRegionBox * pNextRect;
1147 pNextRect = &pReg->rects[pReg->numRects];
1153 assert (r->x1<r->x2);
1154 MEMCHECK (pReg, pNextRect, pReg->rects);
1155 pNextRect->x1 = r->x1;
1157 pNextRect->x2 = r->x2;
1159 pReg->numRects += 1;
1162 assert (pReg->numRects <= pReg->size);
1169 *-----------------------------------------------------------------------
1171 * Overlapping band subtraction. x1 is the left-most point not yet
1178 * pReg may have rectangles added to it.
1180 *-----------------------------------------------------------------------
1184 miSubtractO (GdkRegion *pReg,
1186 GdkRegionBox *r1End,
1188 GdkRegionBox *r2End,
1192 GdkRegionBox * pNextRect;
1198 pNextRect = &pReg->rects[pReg->numRects];
1200 while ((r1 != r1End) && (r2 != r2End))
1205 * Subtrahend missed the boat: go to next subtrahend.
1209 else if (r2->x1 <= x1)
1212 * Subtrahend preceeds minuend: nuke left edge of minuend.
1218 * Minuend completely covered: advance to next minuend and
1219 * reset left fence to edge of new minuend.
1228 * Subtrahend now used up since it doesn't extend beyond
1234 else if (r2->x1 < r1->x2)
1237 * Left part of subtrahend covers part of minuend: add uncovered
1238 * part of minuend to region and skip to next subtrahend.
1241 MEMCHECK(pReg, pNextRect, pReg->rects);
1244 pNextRect->x2 = r2->x1;
1246 pReg->numRects += 1;
1249 assert(pReg->numRects<=pReg->size);
1255 * Minuend used up: advance to new...
1264 * Subtrahend used up
1272 * Minuend used up: add any remaining piece before advancing.
1276 MEMCHECK(pReg, pNextRect, pReg->rects);
1279 pNextRect->x2 = r1->x2;
1281 pReg->numRects += 1;
1283 assert(pReg->numRects<=pReg->size);
1291 * Add remaining minuend rectangles to region.
1296 MEMCHECK(pReg, pNextRect, pReg->rects);
1299 pNextRect->x2 = r1->x2;
1301 pReg->numRects += 1;
1304 assert(pReg->numRects<=pReg->size);
1315 *-----------------------------------------------------------------------
1316 * gdk_region_subtract --
1317 * Subtract other from region and leave the result in region.
1323 * region is overwritten.
1325 *-----------------------------------------------------------------------
1329 gdk_region_subtract (GdkRegion *region,
1332 /* check for trivial reject */
1333 if ((!(region->numRects)) || (!(other->numRects)) ||
1334 (!EXTENTCHECK(®ion->extents, &other->extents)))
1337 miRegionOp (region, region, other, miSubtractO,
1338 miSubtractNonO1, (nonOverlapFunc) NULL);
1341 * Can't alter region's extents before we call miRegionOp because miRegionOp
1342 * depends on the extents of those regions being the unaltered. Besides, this
1343 * way there's no checking against rectangles that will be nuked
1344 * due to coalescing, so we have to examine fewer rectangles.
1346 miSetExtents (region);
1350 gdk_region_xor (GdkRegion *sra,
1355 trb = gdk_region_copy (srb);
1357 gdk_region_subtract (trb, sra);
1358 gdk_region_subtract (sra, srb);
1360 gdk_region_union (sra,trb);
1362 gdk_region_destroy (trb);
1366 * Check to see if the region is empty. Assumes a region is passed
1370 gdk_region_empty (GdkRegion *r)
1372 if (r->numRects == 0)
1379 * Check to see if two regions are equal
1382 gdk_region_equal (GdkRegion *r1,
1387 if (r1->numRects != r2->numRects) return FALSE;
1388 else if (r1->numRects == 0) return TRUE;
1389 else if (r1->extents.x1 != r2->extents.x1) return FALSE;
1390 else if (r1->extents.x2 != r2->extents.x2) return FALSE;
1391 else if (r1->extents.y1 != r2->extents.y1) return FALSE;
1392 else if (r1->extents.y2 != r2->extents.y2) return FALSE;
1394 for(i=0; i < r1->numRects; i++ )
1396 if (r1->rects[i].x1 != r2->rects[i].x1) return FALSE;
1397 else if (r1->rects[i].x2 != r2->rects[i].x2) return FALSE;
1398 else if (r1->rects[i].y1 != r2->rects[i].y1) return FALSE;
1399 else if (r1->rects[i].y2 != r2->rects[i].y2) return FALSE;
1405 gdk_region_point_in (GdkRegion *region,
1411 if (region->numRects == 0)
1413 if (!INBOX(region->extents, x, y))
1415 for (i=0; i<region->numRects; i++)
1417 if (INBOX (region->rects[i], x, y))
1424 gdk_region_rect_in (GdkRegion *region,
1425 GdkRectangle *rectangle)
1428 GdkRegionBox *pboxEnd;
1430 GdkRegionBox *prect = ▭
1431 gboolean partIn, partOut;
1433 gint rx = rectangle->x;
1434 gint ry = rectangle->y;
1438 prect->x2 = rx + rectangle->width;
1439 prect->y2 = ry + rectangle->height;
1441 /* this is (just) a useful optimization */
1442 if ((region->numRects == 0) || !EXTENTCHECK (®ion->extents, prect))
1443 return GDK_OVERLAP_RECTANGLE_OUT;
1448 /* can stop when both partOut and partIn are TRUE, or we reach prect->y2 */
1449 for (pbox = region->rects, pboxEnd = pbox + region->numRects;
1455 continue; /* getting up to speed or skipping remainder of band */
1459 partOut = TRUE; /* missed part of rectangle above */
1460 if (partIn || (pbox->y1 >= prect->y2))
1462 ry = pbox->y1; /* x guaranteed to be == prect->x1 */
1466 continue; /* not far enough over yet */
1470 partOut = TRUE; /* missed part of rectangle to left */
1475 if (pbox->x1 < prect->x2)
1477 partIn = TRUE; /* definitely overlap */
1482 if (pbox->x2 >= prect->x2)
1484 ry = pbox->y2; /* finished with this band */
1485 if (ry >= prect->y2)
1487 rx = prect->x1; /* reset x out to left again */
1492 * Because boxes in a band are maximal width, if the first box
1493 * to overlap the rectangle doesn't completely cover it in that
1494 * band, the rectangle must be partially out, since some of it
1495 * will be uncovered in that band. partIn will have been set true
1505 GDK_OVERLAP_RECTANGLE_PART : GDK_OVERLAP_RECTANGLE_IN) :
1506 GDK_OVERLAP_RECTANGLE_OUT);