Draw a Star using Quartz 2D 不及格的程序员

#define PSIZE 16    // size of the pattern cell
 
static void MyDrawStencilStar (void *info, CGContextRef myContext)
{
    int k;
    double r, theta;
 
    r = 0.8 * PSIZE / 2;
    theta = 2 * M_PI * (2.0 / 5.0); // 144 degrees
 
    CGContextTranslateCTM (myContext, PSIZE/2, PSIZE/2);
 
    CGContextMoveToPoint(myContext, 0, r);
    for (k = 1; k < 5; k++) {
        CGContextAddLineToPoint (myContext,
                    r * sin(k * theta),
                    r * cos(k * theta));
    }
    CGContextClosePath(myContext);
    CGContextFillPath(myContext);
}