Bresenham算法画圆（MFC）

void CCGPainterView::DrawCircle(CDC *pDC, CPoint ptOrigin, int iRadius, COLORREF cLineColor)

{

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

write the circle algorithm for drawing the circle

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

编码圆弧生成算法，调用函数pDC->SetPixelV(point, cLineColor)画像素。

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

    //Bresenham画圆算法

    CPoint point;

    int xi = 0, yi = iRadius;

    int delta_i = (xi + 1) * (xi + 1) + (yi - 1) * (yi - 1) - iRadius * iRadius;

    int delta_s;

    while (yi >= 0) {

        point.x = ptOrigin.x + xi;

        point.y = ptOrigin.y + yi;

        pDC->SetPixelV(point, cLineColor);

        point.x = ptOrigin.x + xi;

        point.y = ptOrigin.y - yi;

        pDC->SetPixelV(point, cLineColor);

        point.x = ptOrigin.x - xi;

        point.y = ptOrigin.y + yi;

        pDC->SetPixelV(point, cLineColor);

        point.x = ptOrigin.x - xi;

        point.y = ptOrigin.y - yi;

        pDC->SetPixelV(point, cLineColor);

        if (delta_i < 0) {

            delta_s = 2 * delta_i + 2 * yi - 1;

            if (delta_s <= 0) {

                xi = xi + 1;

                delta_i = delta_i + 2 * xi + 1;

            }

            else {

                xi = xi + 1;

                yi = yi - 1;

                delta_i = delta_i + 2 * xi - 2 * yi + 2;

            }

        }

        else if (delta_i > 0) {

            delta_s = 2 * delta_i - 2 * xi - 1;

            if (delta_s <= 0) {

                xi = xi + 1;

                yi = yi - 1;

                delta_i = delta_i + 2 * xi - 2 * yi + 2;

            }

            else {

                yi = yi - 1;

                delta_i = delta_i - 2 * yi + 1;

            }

        }

        else {

            xi = xi + 1;

            yi = yi - 1;

            delta_i = delta_i + 2 * xi - 2 * yi + 2;

        }

    }

}