/*
 * COPYRIGHT:         See COPYING in the top level directory
 * PROJECT:           ReactOS Win32k subsystem
 * PURPOSE:           Various Polygon Filling routines for Polygon()
 * FILE:              win32ss/gdi/ntgdi/polyfill.c
 * PROGRAMER:         Mark Tempel
 */

#include <win32k.h>

#define NDEBUG
#include <debug.h>

#define FILL_EDGE_ALLOC_TAG 0x45465044

/*
** This struct is used for book keeping during polygon filling routines.
*/
typedef struct _tagFILL_EDGE
{
    /* Basic line information */
    int FromX;
    int FromY;
    int ToX;
    int ToY;
    int dx;
    int dy;
    int absdx, absdy;
    int x, y;
    int xmajor;

    /* Active Edge List information */
    int XIntercept[2];
    int Error;
    int ErrorMax;
    int XDirection, YDirection;

    /* The next edge in the active Edge List */
    struct _tagFILL_EDGE * pNext;
} FILL_EDGE;

typedef struct _FILL_EDGE_LIST
{
    int Count;
    FILL_EDGE** Edges;
} FILL_EDGE_LIST;

#if 0
static
void
DEBUG_PRINT_ACTIVE_EDGELIST ( FILL_EDGE* list )
{
    FILL_EDGE* pThis = list;
    if (0 == list)
    {
        DPRINT1("List is NULL\n");
        return;
    }

    while(0 != pThis)
    {
        //DPRINT1("EDGE: (%d, %d) to (%d, %d)\n", pThis->FromX, pThis->FromY, pThis->ToX, pThis->ToY);
        DPRINT1("EDGE: [%d,%d]\n", pThis->XIntercept[0], pThis->XIntercept[1] );
        pThis = pThis->pNext;
    }
}
#else
#define DEBUG_PRINT_ACTIVE_EDGELIST(x)
#endif

/*
**  Hide memory clean up.
*/
static
void
FASTCALL
POLYGONFILL_DestroyEdgeList(FILL_EDGE_LIST* list)
{
    int i;

    if (list)
    {
        if (list->Edges)
        {
            for (i = 0; i < list->Count; i++)
            {
                _PRAGMA_WARNING_SUPPRESS(__WARNING_USING_UNINIT_VAR)
                if (list->Edges[i])
                    EngFreeMem(list->Edges[i]);
            }

            EngFreeMem(list->Edges);
        }

        EngFreeMem(list);
    }
}

/*
** This makes and initializes an Edge struct for a line between two points.
*/
static
FILL_EDGE*
FASTCALL
POLYGONFILL_MakeEdge(POINT From, POINT To)
{
    FILL_EDGE* rc = (FILL_EDGE*)EngAllocMem(FL_ZERO_MEMORY, sizeof(FILL_EDGE), FILL_EDGE_ALLOC_TAG);

    if (0 == rc)
        return NULL;

    //DPRINT1("Making Edge: (%d, %d) to (%d, %d)\n", From.x, From.y, To.x, To.y);
    // Now fill the struct.
    if ( To.y < From.y )
    {
        rc->FromX = To.x;
        rc->FromY = To.y;
        rc->ToX = From.x;
        rc->ToY = From.y;
        rc->YDirection = -1;

        // Lines that go up get walked backwards, so need to be offset
        // by -1 in order to make the walk identically on a pixel-level
        rc->Error = -1;
    }
    else
    {
        rc->FromX = From.x;
        rc->FromY = From.y;
        rc->ToX = To.x;
        rc->ToY = To.y;
        rc->YDirection = 1;

        rc->Error = 0;
    }

    rc->x = rc->FromX;
    rc->y = rc->FromY;
    rc->dx   = rc->ToX - rc->FromX;
    rc->dy   = rc->ToY - rc->FromY;
    rc->absdx = abs(rc->dx);
    rc->absdy = abs(rc->dy);

    rc->xmajor = rc->absdx > rc->absdy;

    rc->ErrorMax = max(rc->absdx,rc->absdy);

    rc->Error += rc->ErrorMax / 2;

    rc->XDirection = (rc->dx < 0)?(-1):(1);

    rc->pNext = 0;

    //DPRINT("MakeEdge (%i,%i)->(%i,%i) d=(%i,%i) dir=(%i,%i) err=%i max=%i\n",
    //  From.x, From.y, To.x, To.y, rc->dx, rc->dy, rc->XDirection, rc->YDirection, rc->Error, rc->ErrorMax );

    return rc;
}
/*
** My Edge comparison routine.
** This is for scan converting polygon fill.
** First sort by MinY, then Minx, then slope.
**
** This comparison will help us determine which
** lines will become active first when scanning from
** top (min y) to bottom (max y).
**
** Return Value Meaning
** Negative integer element1 < element2
** Zero element1 = element2
** Positive integer element1 > element2
*/
static
INT
FASTCALL
FILL_EDGE_Compare(FILL_EDGE* Edge1, FILL_EDGE* Edge2)
{
    int e1 = Edge1->XIntercept[0] + Edge1->XIntercept[1];
    int e2 = Edge2->XIntercept[0] + Edge2->XIntercept[1];

    return e1 - e2;
}


/*
** Insert an edge into a list keeping the list in order.
*/
static
void
FASTCALL
POLYGONFILL_ActiveListInsert(FILL_EDGE** activehead, FILL_EDGE* NewEdge )
{
    FILL_EDGE *pPrev, *pThis;
    //DPRINT1("In POLYGONFILL_ActiveListInsert()\n");
    ASSERT(activehead && NewEdge);

    if (!*activehead)
    {
        NewEdge->pNext = NULL;
        *activehead = NewEdge;
        return;
    }
    /*
    ** First lets check to see if we have a new smallest value.
    */
    if (FILL_EDGE_Compare(NewEdge, *activehead) <= 0)
    {
        NewEdge->pNext = *activehead;
        *activehead = NewEdge;
        return;
    }

    /*
    ** Ok, now scan to the next spot to put this item.
    */
    pThis = *activehead;
    pPrev = NULL;
    while ( pThis && FILL_EDGE_Compare(pThis, NewEdge) < 0 )
    {
        pPrev = pThis;
        pThis = pThis->pNext;
    }

    ASSERT(pPrev);
    NewEdge->pNext = pPrev->pNext;
    pPrev->pNext = NewEdge;
    //DEBUG_PRINT_ACTIVE_EDGELIST(*activehead);
}

/*
** Create a list of edges for a list of points.
*/
static
FILL_EDGE_LIST*
FASTCALL
POLYGONFILL_MakeEdgeList(PPOINT Points, int Count)
{
    int CurPt = 0;
    FILL_EDGE_LIST* list = 0;
    FILL_EDGE* e = 0;

    if (0 == Points || 2 > Count)
        return 0;

    list = (FILL_EDGE_LIST*)EngAllocMem(FL_ZERO_MEMORY, sizeof(FILL_EDGE_LIST), FILL_EDGE_ALLOC_TAG);
    if ( 0 == list )
        goto fail;
    list->Count = 0;
    list->Edges = (FILL_EDGE**)EngAllocMem(FL_ZERO_MEMORY, Count*sizeof(FILL_EDGE*), FILL_EDGE_ALLOC_TAG);
    if ( !list->Edges )
        goto fail;

    memset(list->Edges, 0, Count * sizeof(FILL_EDGE*));

    for (CurPt = 1; CurPt < Count; ++CurPt)
    {
        e = POLYGONFILL_MakeEdge ( Points[CurPt-1], Points[CurPt] );
        if (!e)
            goto fail;

        // If a straight horizontal line - who cares?
        if (!e->absdy)
            EngFreeMem(e);
        else
            list->Edges[list->Count++] = e;
    }
    e = POLYGONFILL_MakeEdge ( Points[CurPt-1], Points[0] );
    if ( !e )
        goto fail;

    if (!e->absdy)
        EngFreeMem(e);
    else
        list->Edges[list->Count++] = e;
    return list;

fail:

    DPRINT1("Out Of MEMORY!!\n");
    POLYGONFILL_DestroyEdgeList ( list );
    return 0;
}


/*
** This slow routine uses the data stored in the edge list to
** calculate the x intercepts for each line in the edge list
** for scanline Scanline.
**TODO: Get rid of this floating point arithmetic
*/
static
void
FASTCALL
POLYGONFILL_UpdateScanline(FILL_EDGE* pEdge, int Scanline)
{
    if (0 == pEdge->dy)
        return;

    ASSERT(pEdge->FromY <= Scanline && pEdge->ToY > Scanline);

    if (pEdge->xmajor)
    {
        int steps;

        ASSERT(pEdge->y == Scanline);

        // Now shoot to end of scanline collision
        steps = (pEdge->ErrorMax-pEdge->Error-1)/pEdge->absdy;
        if (steps)
        {
            // Record first collision with scanline
            int x1 = pEdge->x;
            pEdge->x += steps * pEdge->XDirection;
            pEdge->Error += steps * pEdge->absdy;
            ASSERT ( pEdge->Error < pEdge->ErrorMax );
            pEdge->XIntercept[0] = min(x1,pEdge->x);
            pEdge->XIntercept[1] = max(x1,pEdge->x);
        }
        else
        {
            pEdge->XIntercept[0] = pEdge->x;
            pEdge->XIntercept[1] = pEdge->x;
        }

        // We should require exactly 1 step to step onto next scanline...
        ASSERT((pEdge->ErrorMax-pEdge->Error-1) / pEdge->absdy == 0);
        pEdge->x += pEdge->XDirection;
        pEdge->Error += pEdge->absdy;
        ASSERT(pEdge->Error >= pEdge->ErrorMax);

        // Now step onto next scanline...
        pEdge->Error -= pEdge->absdx;
        pEdge->y++;
    }
    else // Then this is a y-major line
    {
        pEdge->XIntercept[0] = pEdge->x;
        pEdge->XIntercept[1] = pEdge->x;

        pEdge->Error += pEdge->absdx;
        pEdge->y++;

        if (pEdge->Error >= pEdge->ErrorMax)
        {
            pEdge->Error -= pEdge->ErrorMax;
            pEdge->x += pEdge->XDirection;
            ASSERT ( pEdge->Error < pEdge->ErrorMax );
        }
    }

    //DPRINT("Line (%d, %d) to (%d, %d) intersects scanline %d at (%d,%d)\n",
    //        pEdge->FromX, pEdge->FromY, pEdge->ToX, pEdge->ToY, Scanline, pEdge->XIntercept[0], pEdge->XIntercept[1] );
}

/*
 * This method updates the Active edge collection for the scanline Scanline.
 */
static
void
APIENTRY
POLYGONFILL_BuildActiveList(
    int Scanline,
    FILL_EDGE_LIST* list,
    FILL_EDGE** ActiveHead)
{
    int i;

    ASSERT(list && ActiveHead);
    *ActiveHead = 0;
    for (i = 0; i < list->Count; i++)
    {
        FILL_EDGE* pEdge = list->Edges[i];
        ASSERT(pEdge);
        if (pEdge->FromY <= Scanline && pEdge->ToY > Scanline)
        {
            POLYGONFILL_UpdateScanline(pEdge, Scanline);
            POLYGONFILL_ActiveListInsert(ActiveHead, pEdge);
        }
    }
}

/*
** This method fills the portion of the polygon that intersects with the scanline
** Scanline.
*/
static
void
APIENTRY
POLYGONFILL_FillScanLineAlternate(
    PDC dc,
    int ScanLine,
    FILL_EDGE* ActiveHead,
    SURFACE *psurf,
    BRUSHOBJ *BrushObj,
    MIX RopMode )
{
    FILL_EDGE *pLeft, *pRight;

    if (!ActiveHead)
        return;

    pLeft = ActiveHead;
    pRight = pLeft->pNext;
    ASSERT(pRight);

    while (NULL != pRight)
    {
        int x1 = pLeft->XIntercept[0];
        int x2 = pRight->XIntercept[1];
        if (x2 > x1)
        {
            RECTL BoundRect;
            BoundRect.top = ScanLine;
            BoundRect.bottom = ScanLine + 1;
            BoundRect.left = x1;
            BoundRect.right = x2;

            //DPRINT("Fill Line (%d, %d) to (%d, %d)\n",x1, ScanLine, x2, ScanLine);
            IntEngLineTo(&psurf->SurfObj,
                         (CLIPOBJ *)&dc->co,
                         BrushObj,
                         x1,
                         ScanLine,
                         x2,
                         ScanLine,
                         &BoundRect,  // Bounding rectangle
                         RopMode);    // MIX
        }
        pLeft = pRight->pNext;
        pRight = pLeft ? pLeft->pNext : NULL;
    }
}

static
void
APIENTRY
POLYGONFILL_FillScanLineWinding(
    PDC dc,
    int ScanLine,
    FILL_EDGE* ActiveHead,
    SURFACE *psurf,
    BRUSHOBJ *BrushObj,
    MIX RopMode )
{
    FILL_EDGE *pLeft, *pRight;
    int x1, x2, winding = 0;
    RECTL BoundRect;

    if (!ActiveHead)
        return;

    BoundRect.top = ScanLine;
    BoundRect.bottom = ScanLine + 1;

    pLeft = ActiveHead;
    winding = pLeft->YDirection;
    pRight = pLeft->pNext;
    ASSERT(pRight);

    // Setup first line...
    x1 = pLeft->XIntercept[0];
    x2 = pRight->XIntercept[1];

    pLeft = pRight;
    pRight = pLeft->pNext;
    winding += pLeft->YDirection;

    while ( NULL != pRight )
    {
        int newx1 = pLeft->XIntercept[0];
        int newx2 = pRight->XIntercept[1];
        if ( winding )
        {
            // Check and see if this new line touches the previous...
            if ((newx1 >= x1 && newx1 <= x2) ||
                (newx2 >= x1 && newx2 <= x2) ||
                (x1 >= newx1 && x1 <= newx2) ||
                (x2 >= newx2 && x2 <= newx2))
            {
                // Yup, just tack it on to our existing line
                x1 = min(x1,newx1);
                x2 = max(x2,newx2);
            }
            else
            {
                // Nope - render the old line..
                BoundRect.left = x1;
                BoundRect.right = x2;

                //DPRINT("Fill Line (%d, %d) to (%d, %d)\n",x1, ScanLine, x2, ScanLine);
                IntEngLineTo(&psurf->SurfObj,
                             (CLIPOBJ *)&dc->co,
                             BrushObj,
                             x1,
                             ScanLine,
                             x2,
                             ScanLine,
                             &BoundRect,  // Bounding rectangle
                             RopMode);    // MIX

                x1 = newx1;
                x2 = newx2;
            }
        }

        pLeft = pRight;
        pRight = pLeft->pNext;
        winding += pLeft->YDirection;
    }

    // There will always be a line left-over, render it now...
    BoundRect.left = x1;
    BoundRect.right = x2;

    //DPRINT("Fill Line (%d, %d) to (%d, %d)\n",x1, ScanLine, x2, ScanLine);
    IntEngLineTo(&psurf->SurfObj,
                 (CLIPOBJ *)&dc->co,
                 BrushObj,
                 x1,
                 ScanLine,
                 x2,
                 ScanLine,
                 &BoundRect,  // Bounding rectangle
                 RopMode);    // MIX
}

// When the fill mode is ALTERNATE, GDI fills the area between odd-numbered and
// even-numbered polygon sides on each scan line. That is, GDI fills the area between the
// first and second side, between the third and fourth side, and so on.

// WINDING Selects winding mode (fills any region with a nonzero winding value).
// When the fill mode is WINDING, GDI fills any region that has a nonzero winding value.
// This value is defined as the number of times a pen used to draw the polygon would go around the region.
// The direction of each edge of the polygon is important.

BOOL
APIENTRY
FillPolygon(
    PDC dc,
    SURFACE *psurf,
    BRUSHOBJ *BrushObj,
    MIX RopMode,
    CONST PPOINT Points,
    int Count,
    RECTL BoundRect )
{
    FILL_EDGE_LIST *list = 0;
    FILL_EDGE *ActiveHead = 0;
    int ScanLine;
    PDC_ATTR pdcattr = dc->pdcattr;
    void
    (APIENTRY *FillScanLine)(
        PDC dc,
        int ScanLine,
        FILL_EDGE* ActiveHead,
        SURFACE *psurf,
        BRUSHOBJ *BrushObj,
        MIX RopMode);

    //DPRINT("FillPolygon\n");

    /* Create Edge List. */
    list = POLYGONFILL_MakeEdgeList(Points, Count);
    /* DEBUG_PRINT_EDGELIST(list); */
    if (NULL == list)
        return FALSE;

    if (WINDING == pdcattr->jFillMode)
        FillScanLine = POLYGONFILL_FillScanLineWinding;
    else /* Default */
        FillScanLine = POLYGONFILL_FillScanLineAlternate;

    /* For each Scanline from BoundRect.bottom to BoundRect.top,
     * determine line segments to draw
     */
    for (ScanLine = BoundRect.top; ScanLine < BoundRect.bottom; ++ScanLine)
    {
        POLYGONFILL_BuildActiveList(ScanLine, list, &ActiveHead);
        //DEBUG_PRINT_ACTIVE_EDGELIST(ActiveHead);
        FillScanLine(dc, ScanLine, ActiveHead, psurf, BrushObj, RopMode);
    }

    /* Free Edge List. If any are left. */
    POLYGONFILL_DestroyEdgeList(list);

    return TRUE;
}

BOOL FASTCALL
IntFillPolygon(
    PDC dc,
    SURFACE *psurf,
    BRUSHOBJ *BrushObj,
    CONST PPOINT Points,
    int Count,
    RECTL DestRect,
    POINTL *BrushOrigin)
{
    FILL_EDGE_LIST *list = 0;
    FILL_EDGE *ActiveHead = 0;
    FILL_EDGE *pLeft, *pRight;
    int ScanLine;

    //DPRINT("IntFillPolygon\n");

    /* Create Edge List. */
    list = POLYGONFILL_MakeEdgeList(Points, Count);
    /* DEBUG_PRINT_EDGELIST(list); */
    if (NULL == list)
        return FALSE;

    /* For each Scanline from DestRect.top to DestRect.bottom, determine line segments to draw */
    for (ScanLine = DestRect.top; ScanLine < DestRect.bottom; ++ScanLine)
    {
        POLYGONFILL_BuildActiveList(ScanLine, list, &ActiveHead);
        //DEBUG_PRINT_ACTIVE_EDGELIST(ActiveHead);

        if (!ActiveHead)
        {
            POLYGONFILL_DestroyEdgeList(list);
            return FALSE;
        }

        pLeft = ActiveHead;
        pRight = pLeft->pNext;
        ASSERT(pRight);

        while (NULL != pRight)
        {
            int x1 = pLeft->XIntercept[0];
            int x2 = pRight->XIntercept[1];

            if (x2 > x1)
            {
                RECTL LineRect;
                LineRect.top = ScanLine;
                LineRect.bottom = ScanLine + 1;
                LineRect.left = x1;
                LineRect.right = x2;

                IntEngBitBlt(&psurf->SurfObj,
                             NULL,
                             NULL,
                             (CLIPOBJ *)&dc->co,
                             NULL,
                             &LineRect,
                             NULL,
                             NULL,
                             BrushObj,
                             BrushOrigin,
                             ROP4_FROM_INDEX(R3_OPINDEX_PATCOPY));
            }

            pLeft = pRight->pNext;
            pRight = pLeft ? pLeft->pNext : NULL;
        }
    }

    /* Free Edge List. If any are left. */
    POLYGONFILL_DestroyEdgeList(list);

    return TRUE;
}

/* EOF */