DDA算法画直线（MFC）

void CCGPainterView::DrawLine(CDC *pDC, CPoint ptStartPoint, CPoint ptEndPoint, COLORREF cLineColor)

{

/*************************************************************

 write the DDA algorithm for drawing the line

 use function: pDC->SetPixelV (point, cLineColor); to drawing a pixel

编码直线生成算法，调用函数 pDC->SetPixelV (point, cLineColor) 画像素。

*************************************************************/

    int x0 = ptStartPoint.x, y0 = ptStartPoint.y;

    int xEnd = ptEndPoint.x, yEnd = ptEndPoint.y;

    int steps;

    int dx = xEnd - x0;

    int dy = yEnd - y0;

    float x = x0, y = y0, xIn, yIn;

    if (fabs(dx) < fabs(dy))

    {

        steps = fabs(dy);

    }

    else

    {

        steps = fabs(dx);

    }

    xIn = float(dx) / float(steps);

    yIn = float(dy) / float(steps);

    CPoint point(int(x + 0.5), int(y + 0.5));

    pDC->SetPixelV(point, cLineColor);

    for (int i = 0; i < steps; i++)

    {

        x += xIn;

        y += yIn;

        CPoint point(int(x + 0.5), int(y + 0.5));

        pDC->SetPixelV(point, cLineColor);

    }

}