windows-xp/Source/XPSP1/NT/drivers/video/ms/w32/disp/misc.c

/******************************Module*Header*******************************\
* Module Name: misc.c
*
* Miscellaneous common routines.
*
* Copyright (c) 1992-1995 Microsoft Corporation
*
\**************************************************************************/

#include "precomp.h"

/******************************Public*Routine******************************\
* BOOL bIntersect
*
* If 'prcl1' and 'prcl2' intersect, has a return value of TRUE and returns
* the intersection in 'prclResult'.  If they don't intersect, has a return
* value of FALSE, and 'prclResult' is undefined.
*
\**************************************************************************/

BOOL bIntersect(
RECTL*  prcl1,
RECTL*  prcl2,
RECTL*  prclResult)
{
    prclResult->left  = max(prcl1->left,  prcl2->left);
    prclResult->right = min(prcl1->right, prcl2->right);

    if (prclResult->left < prclResult->right)
    {
        prclResult->top    = max(prcl1->top,    prcl2->top);
        prclResult->bottom = min(prcl1->bottom, prcl2->bottom);

        if (prclResult->top < prclResult->bottom)
        {
            return(TRUE);
        }
    }

    return(FALSE);
}

/******************************Public*Routine******************************\
* LONG cIntersect
*
* This routine takes a list of rectangles from 'prclIn' and clips them
* in-place to the rectangle 'prclClip'.  The input rectangles don't
* have to intersect 'prclClip'; the return value will reflect the
* number of input rectangles that did intersect, and the intersecting
* rectangles will be densely packed.
*
\**************************************************************************/

LONG cIntersect(
RECTL*  prclClip,
RECTL*  prclIn,         // List of rectangles
LONG    c)              // Can be zero
{
    LONG    cIntersections;
    RECTL*  prclOut;

    cIntersections = 0;
    prclOut        = prclIn;

    for (; c != 0; prclIn++, c--)
    {
        prclOut->left  = max(prclIn->left,  prclClip->left);
        prclOut->right = min(prclIn->right, prclClip->right);

        if (prclOut->left < prclOut->right)
        {
            prclOut->top    = max(prclIn->top,    prclClip->top);
            prclOut->bottom = min(prclIn->bottom, prclClip->bottom);

            if (prclOut->top < prclOut->bottom)
            {
                prclOut++;
                cIntersections++;
            }
        }
    }

    return(cIntersections);
}