xy co-ordinates for different devices

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Created Feb ’22

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I am developing an app that moves a ball along a bezier curve and it works as expected on an iphone 8 plus but when I test on an ipad the animation does not move on the same path as on the iphone. How can I get these to move along the same path for each device. I realize that the xy co-ordinates are different for each device

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Answer 1

Claude31 OP

Feb ’22

Could you show the code where you define Bezier Path ?

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Answer 2

Claude31 OP

Feb ’22

There different coordinate systems :

UIKit : y axis downward
Core Graphics : y axis upward

https://developer.apple.com/library/archive/documentation/2DDrawing/Conceptual/DrawingPrintingiOS/GraphicsDrawingOverview/GraphicsDrawingOverview.html

I don't think there is a difference between iOS and iPadOS.

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Answer 3

dino62454 OP

Feb ’22

here is a sample of the curve code. I am currently using x,y co-ordinates from input. My question is: if I run this on an iphone 8 plus it looks ok but if I run on an ipad the curve is not the same. I assume it is due to the size difference. How do I set the co-ordinates correctly for any device?

path = UIBezierPath() //new code 2-9-22 //addAnimation let moveAlongPath = CAKeyframeAnimation(keyPath: "position")

    //                       newSTx, newSTy
    path.move(to: CGPoint(x: 92, y: 650))
    //                           HPx     HPy                                        arx - 12   iny                             rfx     rfy
    path.addCurve(to: CGPoint(x: 80, y: 100), controlPoint1: CGPoint(x: (newAx - 12), y: 525), controlPoint2: CGPoint(x: newRFx, y: newRFy))

    let shapeLayer = CAShapeLayer()
    shapeLayer.path = path.cgPath
    shapeLayer.strokeColor = UIColor.clear.cgColor
    shapeLayer.fillColor = UIColor.clear.cgColor
    shapeLayer.lineWidth = 3.0
    self.view.layer.addSublayer(shapeLayer)

    moveAlongPath.path = path.cgPath
    moveAlongPath.duration = 5
    moveAlongPath.repeatCount = 0
    moveAlongPath.calculationMode = CAAnimationCalculationMode.paced
    moveAlongPath.timingFunctions = [CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)]
    self.moveAlongPath = moveAlongPath

    let layer = createLayer()
    layer.add(moveAlongPath, forKey: "animate along Path")

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Answer 4

dino62454 OP

Feb ’22

Adding to my question. is there a calculation for xy co-ordinates along a bezier curve or a line drawn from one point to another depending on which device you use? EX: on an iphone 8 plus I start a line on x:92, y:650. In order to position to the same spot on the view for an ipad, how is this calculated? Or does this need to be done manually for each device?

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