Why does a CAShapeLayer's stroke extend out of the frame?

Question

Here\'s sample code:

//Called by VC:

HICircleView *circleView = [[HICircleView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];

// init of circle view

- (id)         


        

Answer 1

You'd rather choose your view's bounds property for calculation. Frame property won't work properly if it's origin is greater than (0,0). You can use CGRectInsets to adjust your circle's rectangle instead of performing transform calculations. This will automatically position the rectangle centered within the original rectangle.

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        CAShapeLayer *borderLayer = [CAShapeLayer layer];
        borderLayer.fillColor = [UIColor whiteColor].CGColor;
        CGFloat lineWidth = 5;
        CGRect rect = CGRectInset(self.bounds, lineWidth / 2, lineWidth / 2);
        borderLayer.path = [UIBezierPath bezierPathWithOvalInRect:rect].CGPath;
        borderLayer.strokeColor = [[UIColor redColor] CGColor];
        borderLayer.lineWidth = lineWidth;
        [self.layer addSublayer:borderLayer];
    }
    return self;
}