Mac OS 贝塞尔曲线画气泡

- (void)drawRect:(NSRect)dirtyRect {
   
    [super drawRect:dirtyRect];
    NSBezierPath*    bezier = [NSBezierPath bezierPath];
    //bezier = [self makeRectPath:bezier withRect:NSMakeRect(50, 50, 200, 400) corner:20];
    
    //bezier = [self makeBubble:bezier withBubbleRect:NSMakeRect(300, 50, 200, 40) corner:15];
    bezier = [self makeBubble:bezier withBubbleRect:NSMakeRect(10, 0, self.bounds.size.width-10, self.bounds.size.height-10) corner:8 atPostion:1];

    [[NSColor greenColor]set];
    [bezier fill];

    [[NSColor redColor]set];
    [bezier stroke];
}

/*
    支持微调气泡
 atPostion:是指小尖角位置，左上 = 1，左下 = 2，右上 = 3，右下 = 4
 */
- (NSBezierPath *)makeBubble:(NSBezierPath *) bezierPath
              withBubbleRect:(NSRect)rect
                      corner:(CGFloat)corner
                   atPostion:(NSInteger)pos
{
   
    //基本偏角40度,正好是引出小三解的位置
    CGFloat baseAngle = 40;
    
    CGFloat cornetOffWidth  = 10;
//    CGFloat cornetOffHeight = 5;
    
    //注angle只设定三个值0, 10，40
    /*
        0: 说明现在小三角相对于矩开来说，已看不出来了，这里直接用直角
        10:说明此时的小三解效果效好
        40:说明此时的矩开和小三角太小，需要调到40度有有效果。
        这三个值会自动的根据外部 corner 参数进行调整
     */
    CGFloat angle = 10;
    
    BOOL midCorner = NO;
    
    //矩形的宽和高
    CGFloat rw = CGRectGetWidth(rect);
    CGFloat rh = CGRectGetHeight(rect);
    
    //最小长度
    CGFloat minDiameter = rw > rh ? rh : rw;

    CGFloat radius = 0;//半径
    if (corner > 0)
    {
   
        radius = corner > minDiameter / 2 ? minDiameter / 2 : corner;
    }
    //最小长度与圆角比
    CGFloat rate = radius / minDiameter;

    //在下角坐标，
    NSPoint leftBottom      = NSMakePoint(CGRectGetMinX(rect), CGRectGetMinY(rect));
    NSPoint leftBottomX     = NSMakePoint(leftBottom.x + radius, leftBottom.y);
    NSPoint leftBottomY     = NSMakePoint(leftBottom.x, leftBottom.y + radius);
    
    NSPoint rightBottom     = NSMakePoint(CGRectGetMaxX(rect), CGRectGetMinY(rect));
    NSPoint rightBottomX    = NSMakePoint(rightBottom.x - radius, rightBottom.y);
    NSPoint rightBottomY    = NSMakePoint(rightBottom.x, rightBottom.y + radius);
    
    NSPoint rightTop = NSMakePoint(CGRectGetMaxX(rect), CGRectGetMaxY(rect));
    NSPoint rightTopX = NSMakePoint(rightTop.x - radius, rightTop.y);
    NSPoint rightTopY = NSMakePoint(rightTop.x, rightTop.y - radius);
    
    
    NSPoint leftTop = NSMakePoint(CGRectGetMinX(rect), CGRectGetMaxY(rect));
    NSPoint leftTopX = NSMakePoint(leftTop.x + radius, leftTop.y);
    NSPoint leftTopY = NSMakePoint(leftTop.x, leftTop.y - radius);


    //最小高度在30以下的，只需要在左或右画三解即可
    if (minDiameter < 30 )
    {
   
        if (rate > 0.33 && rate <= 0.5)
        {
   
            angle = 40;
        }
        else //在中间画直角
        {
   
            angle = 0;
            midCorner = YES;
        }
    }
    else if (minDiameter >= 30 && minDiameter <= 50)
    {
   
        if (rate > 0.2 && rate < 0.4)
        {
   
            angle = 40;
        }
        else if (rate >= 0.4 && rate <= 0.5)
        {
   
            angle = 10; //直角
        }
        else
        {
   
            angle = 0;
        }
    }
    else // 50 以上的