Bresenham算法画直线(MFC）(任意斜率)

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

{

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

 write the Bresenham' line 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。

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

    //Bresenham算法

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

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

    int dx = xEnd - x0;

    int dy = yEnd - y0;

    int converse = 0;

    int dxabs = fabs(dx);

    int dyabs = fabs(dy);

    int s1 = xEnd > x0 ? 1 : -1;

    int s2 = yEnd > y0 ? 1 : -1;

    int x = x0, y = y0;

    if (dyabs > dxabs)

    {

        int tmp = dxabs;

        dxabs = dyabs;

        dyabs = tmp;

        converse = 1;

    }

    int p = 2 * dyabs - dxabs;

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

    {

        CPoint point(x, y);

        pDC->SetPixelV(point, cLineColor);

        if (p >= 0)

        {

            if (converse)

            {

                x += s1;

            }

            else

            {

                y += s2;

            }

            p -= 2 * dxabs;

        }

        if (converse)

        {

            y += s2;

        }

        else

        {

            x += s1;

        }

        p += 2 * dyabs;

    }

}