C / C++ / MFC

// rotate around center
double phi = atan(1.0) * 2/3; // 30 degrees
int x[4];
int y[4];
x[0] = -x1 * cos(phi) - y2 * sin(phi);
y[0] =  x1 * sin(phi) - y2 * cos(phi);

x[1] = -x1 * cos(phi) + y1 * sin(phi);
y[1] =  x1 * sin(phi) + y1 * cos(phi);

x[2] =  x2 * cos(phi)  + y1 * sin(phi);
y[2] = -x2 * sin(phi) + y1 * cos(phi);

x[3] =  x2 * cos(phi) - y2 * sin(phi);
y[3] = -x2 * sin(phi) - y2 * cos(phi);

for (int i=0; i<4; i++)
{
  x[i] += center.x;
  y[i] += center.y;
}

MoveToEx(pCellInfo->hDC,x[3],y[3],NULL); 
for (int i=0; i<4; i++)
{
  LineTo(pCellInfo->hDC, x[i],y[i]);
}

Rick York wrote:

he code looks correct but I find it to be slightly offensive to me sensibilities. Smile

I'm just kidding. I usually make a function or method when I see a sequence of code repeated more than twice. Something like this is generic enough that I definitely would.

Look at the actual values you are passing to MoveToEx and LineTo.

MoveToEx(pCellInfo->hDC,center.x-x1,center.y-y2,NULL); // Here i will find the new axis from the center axis
                                                       // i.e (center.x point - x1,center.y point-y2)
                                                       //so that i get the start point from where i can start to draw rectangle
LineTo(pCellInfo->hDC,center.x-x1,center.y+y1);        //From here i will draw the rectangle