//编码
int CDiamondView::Encode(int x,int y) {
  int res = 0;
  if (x < RectP1.x)
    res = res | 1;
  if (x > RectP2.x)
    res = res | 2;
  if (y < RectP1.y)
    res = res | 8;
  if (y > RectP2.y)
    res = res | 4;
  return res;
}
void CDiamondView::cutLine(POINT p1, POINT p2) {
  CDC* pDC = GetDC();
  CPen newPen, * oldPen;
  newPen.CreatePen(PS_SOLID, 2, RGB(0, 255, 0));
  oldPen = pDC->SelectObject(&newPen);
  int done = 0, accept = 0, reject = 0;
  while (done != 1) {
    int c1 = Encode(p1.x, p1.y);
    int c2 = Encode(p2.x, p2.y);
    if ((c1 & c2) != 0) {
      reject = 1;
      done = 1;
    }
    else if (c1 == 0 && c2 == 0) {
      accept = 1;
      done = 1;
    }
    else {
      if (c1 == 0) {
        POINT t = p1;
        p1 = p2;
        p2 = t;
        int temp = c1;
        c1 = c2;
        c2 = temp;
      }
      if (c1 & 1) {
        int x = RectP1.x;
        int y = (p2.y - p1.y) * 1.0 / ((p2.x - p1.x) * 1.0) * (x - p1.x) + p1.y;
        p1.x = x;
        p1.y = y;
      }
      if (c1 & 2) {
        int x = RectP2.x;
        int y = (p2.y - p1.y) * 1.0 / ((p2.x - p1.x) * 1.0) * (x - p1.x) + p1.y;
        p1.x = x;
        p1.y = y;
      }
      if (c1 & 4) {
        int y = RectP2.y;
        int x = (p2.x - p1.x) * 1.0 / ((p2.y - p1.y) * 1.0) * (y - p1.y) + p1.x;
        p1.x = x;
        p1.y = y;
      }
      if (c1 & 8) {
        int y = RectP1.y;
        int x = (p2.x - p1.x) * 1.0 / ((p2.y - p1.y) * 1.0) * (y - p1.y) + p1.x;
        p1.x = x;
        p1.y = y;
      }
    }
  }
  if (accept) {
    pDC->MoveTo(p1.x, p1.y);
    pDC->LineTo(p2.x, p2.y);
  }
  pDC->SelectObject(oldPen);
  return;
}
//线段裁剪
//裁剪窗口左上角顶点为RectP1,右下角顶点为RectP2,是CDiamondView的成员
void CDiamondView::Cut()
{
  IsCutting = FALSE;
  //以下添加您的代码
  int nVertex = 21;
  int radius = 150;
  POINT* pnt = new POINT[nVertex];
  const double PI = 3.14159265;
  double theta = 2 * PI / nVertex;
  for (int i = 0; i < nVertex; i++) {
    pnt[i].x = radius * cos(i * theta) + MaxX() / 2;
    pnt[i].y = radius * sin(i * theta) + MaxY() / 2;
  }
  for (int i = 0; i < nVertex; i++) {
    for (int j = i + 1; j < nVertex; j++) {
      cutLine(pnt[i], pnt[j]);
    }
  }
}