2D Graphics Board

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Mac Hack display 1 2 3 Mac Hack display ¹ ² ³

I resign by Lawrence J. Krakauer ↩︎
Chess stories by Lawrence J. Krakauer ↩︎
see also 63-chess.mp4 hosted by MIT CSAIL ↩︎

2D Graphics Board,
a 2D graphics image of a chessboard and the pieces of a chess position on a computer display, either fullscreen or board window of a chess GUI, or printer, similar to a chess diagram in print media. A 2D board window should be isotropic and quadratic, with all squares of same size.

Contents

Screenshots

Drawing Pieces

2D Vector Graphics

The C++ code is based on the Windows Microsoft Foundation Class Library, a class extension of the Device Context of the Graphics Device Interface ¹ , in conjunction with "handmade" polygons with coordinates in a x- and y-range of ±16 (positive values right and down), is used in IsiChess to apply vector graphics to draw the pieces in the board window or as figurine notation. For each piece an array of connected lines is declared, the first one a closed polygon, which is filled by the piece color ² :

CDC Class - Device Context, Microsoft Foundation Class Library, MSDN ↩︎
Code by Gerd Isenberg, written in about 2000↩︎

/* Piece Coordinates */
static POINT KnightPoint0[] = {
   { 10, 12},{ 11,  2},{ 10, -3},{  8, -6},
   {  6, -8},{  4, -9},{  1,-11},{  0,-12},
   { -1,-11},{ -2,-11},{ -3,-12},{ -3,-10},
   { -5, -8},{ -6, -6},{ -8,  0},{-10,  2},
   {-10,  4},{ -8,  6},{ -6,  5},{ -5,  4},
   { -4,  2},{ -2,  1},{ -1,  0},{  0, -2},
   { -1,  0},{ -1,  2},{ -2,  4},{ -6,  8},
   { -8, 12},{ 10, 12}
};

static POINT KnightPoint1[] = { { -3, -7},{ -4, -6} };
static POINT KnightPoint2[] = { { -8,  2},{ -9,  3} };

static POINT BishopPoint0[] = {
...

struct PIECEPOLY {
   unsigned int nPoints;
   const POINT *Points;
};

static PIECEPOLY KnightPoly[] = {
   {sizeof (KnightPoint0) / sizeof (KnightPoint0[0]), KnightPoint0},
   {sizeof (KnightPoint1) / sizeof (KnightPoint1[0]), KnightPoint1},
   {sizeof (KnightPoint2) / sizeof (KnightPoint2[0]), KnightPoint2}
};
...

struct PIECEIMAGE {
   int nPolys;
   PIECEPOLY *Poly;
};

static PIECEIMAGE PieceImage[] = {
   {0,  NULL},
   {sizeof (PawnPoly)   / sizeof (PawnPoly  [0]),  PawnPoly},
   {sizeof (BishopPoly) / sizeof (BishopPoly[0]),  BishopPoly},
   {sizeof (KnightPoly) / sizeof (KnightPoly[0]),  KnightPoly},
   {sizeof (RookPoly)   / sizeof (RookPoly  [0]),  RookPoly},
   {sizeof (KingPoly)   / sizeof (KingPoly  [0]),  KingPoly},
   {sizeof (QueenPoly)  / sizeof (QueenPoly [0]),  QueenPoly},
   {0,  NULL},
};

/* Drawing implemented as extension of Windows MFC Device Context Class CDC */
void CIsiDC::drawPiece(const CRect &r, int piece) {
   drawPiece(r, piece, m_sPieceColor[piece&1], m_sPieceBorderColor[piece&1]);
}

void CIsiDC::drawPiece(const CRect &r, int piece, COLORREF piececolor, COLORREF pencolor) {
   CPen pen(PS_SOLID, 1, pencolor);
   CBrush brush(piececolor);
   CPen* pOldPen = SelectObject(&pen);
   CBrush* pOldBrush = SelectObject(&brush);

   PIECEIMAGE *pim = PieceImage + (piece >> 1);
   int i; PIECEPOLY  *p;
   for (i=0, p = pim->Poly; i < pim->nPolys; ++i, ++p) {
      POINT points[64];
      transformPoints (points, p->Points, p->nPoints, r);
      if (i == 0) { /* closed polygon */
         BeginPath();
         Polyline(points, p->nPoints);
         EndPath();
         FillPath();
      }
      Polyline(points, p->nPoints);
   }
   SelectObject(pOldBrush);
   SelectObject(pOldPen);
}

void CIsiDC::transformPoints (POINT* target, const POINT* source, int nPoints, const CRect &r) {
   int width = r.Width();
   int height = r.Height();
   CPoint center = r.CenterPoint();
   while (nPoints--)
      *target++ = transfrom (*source++, width, height, 32, center);
}

POINT CIsiDC::transfrom (const POINT &c, int scalx, int scaly, int qxy, const POINT &trans) {
   return CPoint((c.x*scalx)/qxy, (c.y*scaly)/qxy) + trans;
}

Bitmaps

A more common way is to display pieces in form of bitmaps or pixmaps, small images of pieces, painted with an external program such as GIMP, Paint etc., stored as Raster graphics in an external file or resource format, such as Portable Network Graphics ³ or Windows BMP file format, which may be used in conjunction with Bit blit for scaling.