Question

I am rounding the corners of a rectangle by following

Define a coloredBoxRect and calculate min, max of x and y

CGFloat coloredBoxMargin    =   8;
CGFloat coloredBoxHeight    =   40.0;

coloredBoxRect  =   CGRectMake(coloredBoxMargin,  coloredBoxMargin, self.bounds.size.width-coloredBoxMargin*2, coloredBoxHeight);
CGFloat minx    =   CGRectGetMinX(coloredBoxRect);
CGFloat miny    =   CGRectGetMinY(coloredBoxRect); 
CGFloat midx    =   CGRectGetMidX(coloredBoxRect);     
CGFloat midy    =   CGRectGetMidY(coloredBoxRect); 
CGFloat maxx    =   CGRectGetMaxX(coloredBoxRect); 
CGFloat maxy    =   CGRectGetMaxY(coloredBoxRect);

Then doing

CGMutablePathRef path = CGPathCreateMutable();
//Path stars here
CGPathMoveToPoint  (path, NULL, midx, miny);
// Add an arc for the upper right corner 
1.CGPathAddArcToPoint(path, NULL, maxx, miny,  maxx, maxy, radius);
//Add an arc for the lower right corner
2.CGPathAddArcToPoint(path, NULL, maxx, maxy,  minx, maxy, radius);
// Add an arc for the lower left corner 
3.CGPathAddArcToPoint(path, NULL, minx, maxy,  minx, miny, radius);
// Add an arc for the upper left corner 
4.CGPathAddArcToPoint(path, NULL, minx, miny,  maxx, miny, radius);
CGPathCloseSubpath(path);
CGContextAddPath(context, path);

One of signatures CGPathAddArcToPoint are x and y coordinates of the first and second line tangent. For example to add arc for upper right corner ) maxx+miny+maxx+maxy. And these parameters are confusing me now.

I tried to draw a picture and noticed that (maxx,miny) is not the coordinate of the tangent line. This pair is just a coordinate of top right corner of rectangle………

Does someone advice me on this issue. All comments are welcomed here.
Thanks

Answer 1

Simpler by an order of magnitude is to use [UIBezierPath bezierPathWithRoundedRect:cornerRadius:]. You can then get the CGPath from it afterwards.

See documentation. This probably does the same thing behind the scenes, but why bother doing it yourself?