DavidBoyes

- (CGRect)cropRectForRectSize:(CGSize)rectSize rotation:(float)radians {
    int quadrant = ((int)floor(radians / (M_PI / 2))) & 3;
    float sign_alpha = ((quadrant & 1) == 0) ? radians : M_PI - radians;
    float alpha = fmod((fmod(sign_alpha, M_PI) + M_PI), M_PI);
    
    CGSize bb = CGSizeMake(rectSize.width * cos(alpha) + rectSize.height * sin(alpha), rectSize.width * sin(alpha) + rectSize.height * cos(alpha));
    
    float gamma = rectSize.width < rectSize.height ? atan2(bb.width, bb.height) : atan2(bb.height, bb.width);
    float delta = M_PI - alpha - gamma;
    float length = rectSize.width < rectSize.height ? rectSize.height : rectSize.width;