region.c

realvnc是一个非常流行的远程控制程序

/* $Xorg: Region.c,v 1.6 2001/02/09 02:03:35 xorgcvs Exp $ */
/************************************************************************

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
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Except as contained in this notice, the name of The Open Group shall not be
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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.

************************************************************************/
/* $XFree86: xc/lib/X11/Region.c,v 1.8 2001/12/14 19:54:05 dawes Exp $ */
/*
 * 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...
 */

//#include "Xlibint.h"
#include "Xregion.h"
#include "region.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 void (*voidProcp)();

static void miRegionOp();
/*	Create a new empty region	*/
XRegion
XCreateRegion()
{
    XRegion temp;

    if (! (temp = ( XRegion )Xmalloc( (unsigned) sizeof( REGION ))))
	return (XRegion) NULL;
    if (! (temp->rects = ( BOX * )Xmalloc( (unsigned) sizeof( BOX )))) {
	Xfree((char *) temp);
	return (XRegion) 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( r, rect )
    XRegion 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(rect, source, dest)
    register XRectangle *rect;
    XRegion source, 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 (pReg)
    XRegion	  	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);
}

extern void _XSetClipRectangles();

int
XDestroyRegion( r )
    XRegion r;
{
    Xfree( (char *) r->rects );
    Xfree( (char *) r );
    return 1;
}


/* TranslateRegion(pRegion, x, y)
   translates in place
   added by raymond
*/

int
XOffsetRegion(pRegion, x, y)
    register XRegion 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(r, s, t, dx, xdir, grow)
    XRegion r, s, t;
    register unsigned dx;
    register int xdir, 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(r, dx, dy)
    XRegion r;
    int dx, dy;
{
    XRegion s, t;
    int grow;

    if (!dx && !dy) return 0;
    if ((! (s = XCreateRegion()))  || (! (t = XCreateRegion()))) 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;
}

#ifdef notdef
/***********************************************************
 *     Bop down the array of rects until we have passed
 *     scanline y.  numRects is the size of the array.
 ***********************************************************/

static BOX 
*IndexRects(rects, numRects, y)
    register BOX *rects;
    register int numRects;
    register int y;
{
     while ((numRects--) && (rects->y2 <= y))
        rects++;
     return(rects);
}
#endif

/*======================================================================
 *	    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 (pReg, r1, r1End, r2, r2End, y1, y2)
    register XRegion	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(reg1, reg2, newReg)
    XRegion 	  	reg1;
    XRegion	  	reg2;          /* source regions     */
    register XRegion 	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, 
    		(voidProcp) miIntersectO, (voidProcp) NULL, (voidProcp) 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(dstrgn, rgn)
    register XRegion dstrgn;
    register XRegion 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)));
    }
}

#ifdef notdef

/*
 *  combinRegs(newReg, reg1, reg2)
 *    if one region is above or below the other.
*/ 

static void
combineRegs(newReg, reg1, reg2)
    register XRegion newReg;
    XRegion reg1;
    XRegion reg2;
{
    register XRegion tempReg;
    register BOX *rects;
    register BOX *rects1;
    register BOX *rects2;
    register int total;

    rects1 = reg1->rects;
    rects2 = reg2->rects;

    total = reg1->numRects + reg2->numRects;
    if (! (tempReg = XCreateRegion()))
	return;
    tempReg->size = total;
    /*  region 1 is below region 2  */
    if (reg1->extents.y1 > reg2->extents.y1)
    {
        miRegionCopy(tempReg, reg2);
        rects = &tempReg->rects[tempReg->numRects];
        total -= tempReg->numRects;
        while (total--)
            *rects++ = *rects1++;
    }
    else
    {
        miRegionCopy(tempReg, reg1);
        rects = &tempReg->rects[tempReg->numRects];
        total -= tempReg->numRects;
        while (total--)
            *rects++ = *rects2++;
    }
    tempReg->extents = reg1->extents;
    tempReg->numRects = reg1->numRects + reg2->numRects;
    EXTENTS(&reg2->extents, tempReg);  
    miRegionCopy(newReg, tempReg);
    Xfree((char *)tempReg);
}

/*
 *  QuickCheck checks to see if it does not have to go through all the
 *  the ugly code for the region call.  It returns 1 if it did all
 *  the work for Union, otherwise 0 - still work to be done.
*/ 

static int
QuickCheck(newReg, reg1, reg2)
    XRegion newReg, reg1, reg2;
{

    /*  if unioning with itself or no rects to union with  */
    if ( (reg1 == reg2) || (!(reg1->numRects)) )
    {
        miRegionCopy(newReg, reg2);
        return TRUE;
    }

    /*   if nothing to union   */
    if (!(reg2->numRects))