qregion_unix.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

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************************************************************************/
/* $XFree86: xc/lib/X11/PolyReg.c,v 1.1.1.2.8.2 1998/10/04 15:22:49 hohndel Exp $ */

#define LARGE_COORDINATE 1000000
#define SMALL_COORDINATE -LARGE_COORDINATE

/*
 *     InsertEdgeInET
 *
 *     Insert the given edge into the edge table.
 *     First we must find the correct bucket in the
 *     Edge table, then find the right slot in the
 *     bucket.  Finally, we can insert it.
 *
 */
static void InsertEdgeInET(EdgeTable *ET, EdgeTableEntry *ETE, int scanline,
                           ScanLineListBlock **SLLBlock, int *iSLLBlock)
{
    register EdgeTableEntry *start, *prev;
    register ScanLineList *pSLL, *pPrevSLL;
    ScanLineListBlock *tmpSLLBlock;

    /*
     * find the right bucket to put the edge into
     */
    pPrevSLL = &ET->scanlines;
    pSLL = pPrevSLL->next;
    while (pSLL && (pSLL->scanline < scanline)) {
        pPrevSLL = pSLL;
        pSLL = pSLL->next;
    }

    /*
     * reassign pSLL (pointer to ScanLineList) if necessary
     */
    if ((!pSLL) || (pSLL->scanline > scanline)) {
        if (*iSLLBlock > SLLSPERBLOCK-1)
        {
            tmpSLLBlock =
                  (ScanLineListBlock *)malloc(sizeof(ScanLineListBlock));
            (*SLLBlock)->next = tmpSLLBlock;
            tmpSLLBlock->next = (ScanLineListBlock *)NULL;
            *SLLBlock = tmpSLLBlock;
            *iSLLBlock = 0;
        }
        pSLL = &((*SLLBlock)->SLLs[(*iSLLBlock)++]);

        pSLL->next = pPrevSLL->next;
        pSLL->edgelist = (EdgeTableEntry *)NULL;
        pPrevSLL->next = pSLL;
    }
    pSLL->scanline = scanline;

    /*
     * now insert the edge in the right bucket
     */
    prev = 0;
    start = pSLL->edgelist;
    while (start && (start->bres.minor_axis < ETE->bres.minor_axis)) {
        prev = start;
        start = start->next;
    }
    ETE->next = start;

    if (prev)
        prev->next = ETE;
    else
        pSLL->edgelist = ETE;
}

/*
 *     CreateEdgeTable
 *
 *     This routine creates the edge table for
 *     scan converting polygons.
 *     The Edge Table (ET) looks like:
 *
 *    EdgeTable
 *     --------
 *    |  ymax  |        ScanLineLists
 *    |scanline|-->------------>-------------->...
 *     --------   |scanline|   |scanline|
 *                |edgelist|   |edgelist|
 *                ---------    ---------
 *                    |             |
 *                    |             |
 *                    V             V
 *              list of ETEs   list of ETEs
 *
 *     where ETE is an EdgeTableEntry data structure,
 *     and there is one ScanLineList per scanline at
 *     which an edge is initially entered.
 *
 */

static void CreateETandAET(register int count, register const QPoint *pts,
                           EdgeTable *ET, EdgeTableEntry *AET, register EdgeTableEntry *pETEs,
                           ScanLineListBlock *pSLLBlock)
{
    register const QPoint *top,
                          *bottom,
                          *PrevPt,
                          *CurrPt;
    int iSLLBlock = 0;
    int dy;

    if (count < 2)
        return;

    /*
     *  initialize the Active Edge Table
     */
    AET->next = 0;
    AET->back = 0;
    AET->nextWETE = 0;
    AET->bres.minor_axis = SMALL_COORDINATE;

    /*
     *  initialize the Edge Table.
     */
    ET->scanlines.next = 0;
    ET->ymax = SMALL_COORDINATE;
    ET->ymin = LARGE_COORDINATE;
    pSLLBlock->next = 0;

    PrevPt = &pts[count - 1];

    /*
     *  for each vertex in the array of points.
     *  In this loop we are dealing with two vertices at
     *  a time -- these make up one edge of the polygon.
     */
    while (count--) {
        CurrPt = pts++;

        /*
         *  find out which point is above and which is below.
         */
        if (PrevPt->y() > CurrPt->y()) {
            bottom = PrevPt;
            top = CurrPt;
            pETEs->ClockWise = 0;
        } else {
            bottom = CurrPt;
            top = PrevPt;
            pETEs->ClockWise = 1;
        }

        /*
         * don't add horizontal edges to the Edge table.
         */
        if (bottom->y() != top->y()) {
            pETEs->ymax = bottom->y() - 1;  /* -1 so we don't get last scanline */

            /*
             *  initialize integer edge algorithm
             */
            dy = bottom->y() - top->y();
            BRESINITPGONSTRUCT(dy, top->x(), bottom->x(), pETEs->bres)

            InsertEdgeInET(ET, pETEs, top->y(), &pSLLBlock, &iSLLBlock);

            if (PrevPt->y() > ET->ymax)
                ET->ymax = PrevPt->y();
            if (PrevPt->y() < ET->ymin)
                ET->ymin = PrevPt->y();
            ++pETEs;
        }

        PrevPt = CurrPt;
    }
}

/*
 *     loadAET
 *
 *     This routine moves EdgeTableEntries from the
 *     EdgeTable into the Active Edge Table,
 *     leaving them sorted by smaller x coordinate.
 *
 */

static void loadAET(register EdgeTableEntry *AET, register EdgeTableEntry *ETEs)
{
    register EdgeTableEntry *pPrevAET;
    register EdgeTableEntry *tmp;

    pPrevAET = AET;
    AET = AET->next;
    while (ETEs) {
        while (AET && AET->bres.minor_axis < ETEs->bres.minor_axis) {
            pPrevAET = AET;
            AET = AET->next;
        }
        tmp = ETEs->next;
        ETEs->next = AET;
        if (AET)
            AET->back = ETEs;
        ETEs->back = pPrevAET;
        pPrevAET->next = ETEs;
        pPrevAET = ETEs;

        ETEs = tmp;
    }
}

/*
 *     computeWAET
 *
 *     This routine links the AET by the
 *     nextWETE (winding EdgeTableEntry) link for
 *     use by the winding number rule.  The final
 *     Active Edge Table (AET) might look something
 *     like:
 *
 *     AET
 *     ----------  ---------   ---------
 *     |ymax    |  |ymax    |  |ymax    |
 *     | ...    |  |...     |  |...     |
 *     |next    |->|next    |->|next    |->...
 *     |nextWETE|  |nextWETE|  |nextWETE|
 *     ---------   ---------   ^--------
 *         |                   |       |
 *         V------------------->       V---> ...
 *
 */
static void computeWAET(register EdgeTableEntry *AET)
{
    register EdgeTableEntry *pWETE;
    register int inside = 1;
    register int isInside = 0;

    AET->nextWETE = 0;
    pWETE = AET;
    AET = AET->next;
    while (AET) {
        if (AET->ClockWise)
            ++isInside;
        else
            --isInside;

        if (!inside && !isInside || inside && isInside) {
            pWETE->nextWETE = AET;
            pWETE = AET;
            inside = !inside;
        }
        AET = AET->next;
    }
    pWETE->nextWETE = 0;
}

/*
 *     InsertionSort
 *
 *     Just a simple insertion sort using
 *     pointers and back pointers to sort the Active
 *     Edge Table.
 *
 */

static int InsertionSort(register EdgeTableEntry *AET)
{
    register EdgeTableEntry *pETEchase;
    register EdgeTableEntry *pETEinsert;
    register EdgeTableEntry *pETEchaseBackTMP;
    register int changed = 0;

    AET = AET->next;
    while (AET) {
        pETEinsert = AET;
        pETEchase = AET;
        while (pETEchase->back->bres.minor_axis > AET->bres.minor_axis)
            pETEchase = pETEchase->back;

        AET = AET->next;
        if (pETEchase != pETEinsert) {
            pETEchaseBackTMP = pETEchase->back;
            pETEinsert->back->next = AET;
            if (AET)
                AET->back = pETEinsert->back;
            pETEinsert->next = pETEchase;
            pETEchase->back->next = pETEinsert;
            pETEchase->back = pETEinsert;
            pETEinsert->back = pETEchaseBackTMP;
            changed = 1;
        }
    }
    return changed;
}

/*
 *     Clean up our act.
 */
static void FreeStorage(register ScanLineListBlock *pSLLBlock)
{
    register ScanLineListBlock *tmpSLLBlock;

    while (pSLLBlock) {
        tmpSLLBlock = pSLLBlock->next;
        free(pSLLBlock);
        pSLLBlock = tmpSLLBlock;
    }
}

/*
 *     Create an array of rectangles from a list of points.
 *     If indeed these things (POINTS, RECTS) are the same,
 *     then this proc is still needed, because it allocates
 *     storage for the array, which was allocated on the
 *     stack by the calling procedure.
 *
 */
static void PtsToRegion(register int numFullPtBlocks, register int iCurPtBlock,
                       POINTBLOCK *FirstPtBlock, QRegionPrivate *reg)
{
    register QRect *rects;
    register QPoint *pts;
    register POINTBLOCK *CurPtBlock;
    register int i;
    register QRect *extents;
    register int numRects;

    extents = &reg->extents;

    numRects = ((numFullPtBlocks * NUMPTSTOBUFFER) + iCurPtBlock) >> 1;

    reg->rects.resize(numRects);

    CurPtBlock = FirstPtBlock;
    rects = reg->rects.data() - 1;
    numRects = 0;
    extents->setLeft(INT_MAX);
    extents->setRight(INT_MIN);

    for (; numFullPtBlocks >= 0; --numFullPtBlocks) {
        /* the loop uses 2 points per iteration */
        i = NUMPTSTOBUFFER >> 1;
        if (!numFullPtBlocks)
            i = iCurPtBlock >> 1;
        if(i) {
            for (pts = CurPtBlock->pts; i--; pts += 2) {
                if (pts->x() == pts[1].x())
                    continue;
                if (numRects && pts->x() == rects->left() && pts->y() == rects->bottom() + 1
                    && pts[1].x() == rects->right()
                    && (numRects == 1 || rects[-1].top() != rects->top())
                    && (i && pts[2].y() > pts[1].y())) {
                    rects->setBottom(pts[1].y());
                    continue;
                }
                ++numRects;
                ++rects;
                rects->setCoords(pts->x(), pts->y(), pts[1].x() - 1, pts[1].y());
                if (rects->left() < extents->left())
                    extents->setLeft(rects->left());
                if (rects->right() > extents->right())
                    extents->setRight(rects->right());
            }
        }
        CurPtBlock = CurPtBlock->next;
    }

    if (numRects) {
        extents->setTop(reg->rects[0].top());
        extents->setBottom(rects->bottom());
    } else {
        extents->setCoords(0, 0, 0, 0);
    }
    reg->numRects = numRects;
}

/*
 *     polytoregion
 *
 *     Scan converts a polygon by returning a run-length
 *     encoding of the resultant bitmap -- the run-