Question

I am wondering is there any functionality in Core Graphics that will let you specify an inset for a non rectangular shape ie something comparable to CGRectInset? I’m creating a path that is comprised of a bunch of quadratic bezier curves which make up a special type of elipse, and I’d like to fit in a smaller type of elipse inside of it. Yes, I know I could probably do this manually, but wondering if Apple has an easy way to do it?

Answer 1

CoreGraphics does not specify functions related to shapes other than *rect*angles because it doesn’t have to. Any drawing that you do is the own problem, and therefore, your own solution is required. It would be possible to quasi-copy a CGRectMake()-esque element yourself (it’s just a c struct).

struct CFIElipseRect {
   CGPoint origin;
   CGSize size;
   CGFloat arcLength;
   CGFloat vertices;
   CGFloat cornerRadius; //optional, just a thought.
};
typedef struct CFIElipseRect CFIElipseRect;


CFIElipseRect CFIElipseRectMake(CGPoint origin, CGSize size, CGFloat arcLength, CGFloat vertices, CGFloat cornerRadius) {
    CFIElipseRect rect;
    rect.origin = origin;
    rect.size = size;
    rect.arcLength = arcLength;
    rect.vertices = vertices;
    rect.cornerRadius = cornerRadius;
    return rect;
}

CFIElipseRect CFIElipseRectInset(CFIElipseRect rect, float dx, float dy) {
    rect.size.x -= dx;
    rect.size.y -= dy;
    return rect;
}