Re: Draw an arc given 2 angles.

[Eric E. Dolecki]

Thanks. I figured out things on this end. I have it now. It always seems to
happen after I fire off an email :)

Eric

On Thu, Jan 25, 2018 at 12:57 PM Saagar Jha  wrote:

>
> Saagar Jha
>
> On Jan 25, 2018, at 09:47, Eric E. Dolecki  wrote:
>
> I've been googling without great success so far.
>
> I would like to draw a 6px thick red arc (not wedge), 0º at the top of the
> screen, and from say 60° - 110º. Assume I have to create a UIBezierPath,
> and then create a CAShapeLayer with that bezier path? Then add the shape
> layer to a UIView that I have.
>
> I'll be given the 2 angles to use via sliders - so I can update the arc
> (later). I just want to nail down an initial arc. Below doesn't work.
>
> 1. How do I get things so 0º is at the top, rotate circle 90º
> counterclockwise?
> 2. How can I get the red arc?
>
> Thanks!
>
> // Circle is a UIView with a height and width of 300
>
> let centre = CGPoint (x: circle.frame.size.width / 2, y: circle.frame.size.
> height / 2)
>
> let startAngle: CGFloat = 70.0
>
> let endAngle: CGFloat = 100
>
> let a_path = UIBezierPath()
>
> a_path.move(to: CGPoint(x: circle.frame.width / 2, y: circle.frame.height
> / 2))
>
>
> It looks like you’re starting from the center of the arc. I don’t think
> your arc will show up if you do this since the “radius” of it is 0.
>
>
> a_path.addArc(withCenter: centre, radius: 150, startAngle: CGFloat
> (startAngle).toRadians(), endAngle: CGFloat(endAngle).toRadians(),
> clockwise: true)
>
>
> // Want a red stroke on the arc, I get filled black wedge instead
>
> let redColor = UIColor.red
>
> redColor.setStroke()
>
> a_path.lineWidth = 6
>
> a_path.lineCapStyle = .round
>
> a_path.stroke()
>
>
>
> let a_shapeLayer = CAShapeLayer()
>
> a_shapeLayer.path = a_path.cgPath
>
>
> circle.layer.sublayers?.forEach { $0.removeFromSuperlayer() }
>
> circle.layer.addSublayer(a_shapeLayer)
>
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Re: Draw an arc given 2 angles.

[Saagar Jha]

Saagar Jha

> On Jan 25, 2018, at 09:47, Eric E. Dolecki  wrote:
> 
> I've been googling without great success so far.
> 
> I would like to draw a 6px thick red arc (not wedge), 0º at the top of the
> screen, and from say 60° - 110º. Assume I have to create a UIBezierPath,
> and then create a CAShapeLayer with that bezier path? Then add the shape
> layer to a UIView that I have.
> 
> I'll be given the 2 angles to use via sliders - so I can update the arc
> (later). I just want to nail down an initial arc. Below doesn't work.
> 
> 1. How do I get things so 0º is at the top, rotate circle 90º
> counterclockwise?
> 2. How can I get the red arc?
> 
> Thanks!
> 
> // Circle is a UIView with a height and width of 300
> 
> let centre = CGPoint (x: circle.frame.size.width / 2, y: circle.frame.size.
> height / 2)
> 
> let startAngle: CGFloat = 70.0
> 
> let endAngle: CGFloat = 100
> 
> let a_path = UIBezierPath()
> 
> a_path.move(to: CGPoint(x: circle.frame.width / 2, y: circle.frame.height
> / 2))

It looks like you’re starting from the center of the arc. I don’t think your 
arc will show up if you do this since the “radius” of it is 0.

> 
> a_path.addArc(withCenter: centre, radius: 150, startAngle: CGFloat
> (startAngle).toRadians(), endAngle: CGFloat(endAngle).toRadians(),
> clockwise: true)
> 
> 
> // Want a red stroke on the arc, I get filled black wedge instead
> 
> let redColor = UIColor.red
> 
> redColor.setStroke()
> 
> a_path.lineWidth = 6
> 
> a_path.lineCapStyle = .round
> 
> a_path.stroke()
> 
> 
> 
> let a_shapeLayer = CAShapeLayer()
> 
> a_shapeLayer.path = a_path.cgPath
> 
> 
> circle.layer.sublayers?.forEach { $0.removeFromSuperlayer() }
> 
> circle.layer.addSublayer(a_shapeLayer)
> ___
> 
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Draw an arc given 2 angles.

[Eric E. Dolecki]

I've been googling without great success so far.

I would like to draw a 6px thick red arc (not wedge), 0º at the top of the
screen, and from say 60° - 110º. Assume I have to create a UIBezierPath,
and then create a CAShapeLayer with that bezier path? Then add the shape
layer to a UIView that I have.

I'll be given the 2 angles to use via sliders - so I can update the arc
(later). I just want to nail down an initial arc. Below doesn't work.

1. How do I get things so 0º is at the top, rotate circle 90º
counterclockwise?
2. How can I get the red arc?

Thanks!

 // Circle is a UIView with a height and width of 300

 let centre = CGPoint (x: circle.frame.size.width / 2, y: circle.frame.size.
height / 2)

 let startAngle: CGFloat = 70.0

 let endAngle: CGFloat = 100

 let a_path = UIBezierPath()

 a_path.move(to: CGPoint(x: circle.frame.width / 2, y: circle.frame.height
/ 2))

 a_path.addArc(withCenter: centre, radius: 150, startAngle: CGFloat
(startAngle).toRadians(), endAngle: CGFloat(endAngle).toRadians(),
clockwise: true)


 // Want a red stroke on the arc, I get filled black wedge instead

 let redColor = UIColor.red

 redColor.setStroke()

 a_path.lineWidth = 6

 a_path.lineCapStyle = .round

 a_path.stroke()



 let a_shapeLayer = CAShapeLayer()

 a_shapeLayer.path = a_path.cgPath


 circle.layer.sublayers?.forEach { $0.removeFromSuperlayer() }

 circle.layer.addSublayer(a_shapeLayer)
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