Mask Image with custom UIBazierPath swift

Question

I have created UIBezierPath with custom shape then I need to make it mask for image always I got empty image here is my code First I created the path, then create image and last create my mask but it is not working

here is image I need to mask it dropbox.com/s/tnxgx7g1uvb1zj7/TeethMask.png?dl=0 here is UIBazier path dropbox.com/s/nz93n1vgvj6c6y0/… I need to mask this image in this path The output is something like this https://www.dropbox.com/s/gueyhdmmdcfvyiq/image.png?dl=0

Here is ViewController class

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let tapGR = UITapGestureRecognizer(target: self, action: #selector(didTap))

        self.view.addGestureRecognizer(tapGR)
    }

    @objc func didTap(tapGR: UITapGestureRecognizer) {

        let tapPoint = tapGR.location(in: self.view)

        if #available(iOS 11.0, *) {
            let shapeView = ShapeView(origin: tapPoint)
             self.view.addSubview(shapeView)
        } else {
            // Fallback on earlier versions
        }


    }

}

Here is ShapeView class

import UIKit

@available(iOS 11.0, *)
class ShapeView: UIView {

    let size: CGFloat = 150
    let lineWidth: CGFloat = 3
    var fillColor: UIColor!
    var path: UIBezierPath!

    init(origin: CGPoint) {
        super.init(frame: CGRect(x: 0.0, y: 0.0, width: size, height: size))
        self.fillColor = randomColor()
        self.path = mouthPath()
        self.center = origin
        self.backgroundColor = UIColor.clear
    }


    func randomColor() -> UIColor {
        let hue:CGFloat = CGFloat(Float(arc4random()) / Float(UINT32_MAX))
        return UIColor(hue: hue, saturation: 0.8, brightness: 1.0, alpha: 0.8)
    }


    func mouthPath() -> UIBezierPath{
        let pointsArray = [CGPoint(x:36 , y:36 ),CGPoint(x:41 , y:36 ),CGPoint(x:45 , y:36 ),CGPoint(x:49 , y:36 ),CGPoint(x:53 , y:36 ),CGPoint(x:58 , y: 37),CGPoint(x:64 , y:37 ),CGPoint(x:69 , y:36 ),CGPoint(x:65 , y:29 ),CGPoint(x:58 , y:24 ),CGPoint(x:50 , y:22 ),CGPoint(x:42 , y:23 ),CGPoint(x:36 , y:28 ),CGPoint(x:32 , y:35 )]

        let newPath = UIBezierPath()
        let factor:CGFloat = 10
        for i in 0...pointsArray.count - 1 { // last point is 0,0
            let point = pointsArray[i]
            let currentPoint1 = CGPoint(x: point.x  * factor , y: point.y * factor)
        if i == 0 {
            newPath.move(to: currentPoint1)
        } else {
            newPath.addLine(to: currentPoint1)

            }
            }
            newPath.addLine(to: CGPoint(x: pointsArray[0].x  * factor, y: pointsArray[0].y * factor))
            newPath.close()

        let imageTemplate = UIImageView()
        imageTemplate.image =  UIImage(named: "TeethMask")
        self.addSubview(imageTemplate)
        self.bringSubviewToFront(imageTemplate)
        imageTemplate.frame = self.frame

        let mask = CAShapeLayer(layer: self.layer)
        mask.frame = newPath.bounds
        mask.fillColor = UIColor.clear.cgColor
        mask.strokeColor = UIColor.black.cgColor
        mask.path = newPath.cgPath
        mask.shouldRasterize = true
        imageTemplate.layer.mask = mask
        imageTemplate.layer.addSublayer(mask)
    }
}

Can you please add photo how you want your image looks like? — shraddha11, Apr 06 '20 at 11:48
sure, here is image I need to mask it https://www.dropbox.com/s/tnxgx7g1uvb1zj7/TeethMask.png?dl=0 here is UIBazier path https://www.dropbox.com/s/nz93n1vgvj6c6y0/Screen%20Shot%202020-04-06%20at%202.10.22%20PM.png?dl=0 I need to mask this image in this path, is it cleare ? — yasmina, Apr 06 '20 at 12:15
@yasmina - ok... what do you mean by *"need to mask"*? Are you trying to draw a path sort-of around the teeth, so only the teeth show? Or are you just trying to draw an outline around them? — DonMag, Apr 06 '20 at 12:19
@DonMag I need the teeth inside the path dropbox.com/s/tnxgx7g1uvb1zj7/TeethMask.png?dl=0 here is path dropbox.com/s/nz93n1vgvj6c6y0/… I need to mask this image in this path, is it cleare — yasmina, Apr 06 '20 at 12:21
@yasmina - The `func` in the code you posted is supposed to return a `UIBezierPath` but it's not returning anything. Is this part of a custom `UIView` class? Or did you copy/paste sections from a `UIViewController` class? Edit your question and post the full class code that you are trying to use. — DonMag, Apr 06 '20 at 12:58
Still not quite clear what you're going for... do you want it to look like **(A)** https://i.stack.imgur.com/mSbh6.png or **(B)** https://i.stack.imgur.com/ERqMg.png ?? Or something else? — DonMag, Apr 06 '20 at 13:39

score 0 · Accepted Answer · answered Apr 06 '20 at 15:50

Well, you're doing a few things wrong...

The "teeth" image you linked:

has a native size of 461 x 259. So, I'm going to use a proportional "target" size of 200 x 112.

First, shape layers use 0,0 at upper-left. Your original points array:

let pointsArray = [
    CGPoint(x: 36, y: 36),
    CGPoint(x: 41, y: 36),
    CGPoint(x: 45, y: 36),
    CGPoint(x: 49, y: 36),
    CGPoint(x: 53, y: 36),
    CGPoint(x: 58, y: 37),
    CGPoint(x: 64, y: 37),
    CGPoint(x: 69, y: 36),
    CGPoint(x: 65, y: 29),
    CGPoint(x: 58, y: 24),
    CGPoint(x: 50, y: 22),
    CGPoint(x: 42, y: 23),
    CGPoint(x: 36, y: 28),
    CGPoint(x: 32, y: 35),
]

gives this shape:

If we invert the y-coordinates:

let pointsArray = [
    CGPoint(x: 36.0, y: 23.0),
    CGPoint(x: 41.0, y: 23.0),
    CGPoint(x: 45.0, y: 23.0),
    CGPoint(x: 49.0, y: 23.0),
    CGPoint(x: 53.0, y: 23.0),
    CGPoint(x: 58.0, y: 22.0),
    CGPoint(x: 64.0, y: 22.0),
    CGPoint(x: 69.0, y: 23.0),
    CGPoint(x: 65.0, y: 30.0),
    CGPoint(x: 58.0, y: 35.0),
    CGPoint(x: 50.0, y: 37.0),
    CGPoint(x: 42.0, y: 36.0),
    CGPoint(x: 36.0, y: 31.0),
    CGPoint(x: 32.0, y: 24.0),
]

we get this shape:

It will be difficult to get things to "line up" correctly if your shape is offset like that, so we can "normalize" the points to start at top-left:

let pointsArray: [CGPoint] = [
    CGPoint(x: 4.0, y: 1.0),
    CGPoint(x: 9.0, y: 1.0),
    CGPoint(x: 13.0, y: 1.0),
    CGPoint(x: 17.0, y: 1.0),
    CGPoint(x: 21.0, y: 1.0),
    CGPoint(x: 26.0, y: 0.0),
    CGPoint(x: 32.0, y: 0.0),
    CGPoint(x: 37.0, y: 1.0),
    CGPoint(x: 33.0, y: 8.0),
    CGPoint(x: 26.0, y: 13.0),
    CGPoint(x: 18.0, y: 15.0),
    CGPoint(x: 10.0, y: 14.0),
    CGPoint(x: 4.0, y: 9.0),
    CGPoint(x: 0.0, y: 2.0),
]

resulting in:

However, we want the shape to fit the image, so we can scale the UIBezierPath to the bounds of the imageView:

    // need to scale the path to self.bounds
    let scaleW = bounds.width / pth.bounds.width
    let scaleH = bounds.height / pth.bounds.height

    let trans = CGAffineTransform(scaleX: scaleW, y: scaleH)
    pth.apply(trans)

and we're here:

The only thing left is to use that as a mask for the image.

I'm going to suggest subclassing UIImageView instead of UIView ... that way you can set the .image property without needing to add another view as a subview. Also, I think you'll find it much easier to manage the size of the custom, masked image in your controller code, rather than inside the custom class.

Here is a demo view controller and a custom MouthShapeView:

class TeethViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let tapGR = UITapGestureRecognizer(target: self, action: #selector(didTap))

        self.view.addGestureRecognizer(tapGR)
    }

    @objc func didTap(tapGR: UITapGestureRecognizer) {

        let tapPoint = tapGR.location(in: self.view)

        if #available(iOS 11.0, *) {

            // make sure you can load the image
            if let img = UIImage(named: "TeethMask") {
                // create custom ShapeView with image
                let shapeView = MouthShapeView(image: img)
                // if you want to use original image proportions
                // set the width you want and calculate a proportional height
                // based on the original image size
                let targetWidth: CGFloat = 200.0
                let targetHeight: CGFloat = img.size.height / img.size.width * targetWidth
                // set the frame size
                shapeView.frame.size = CGSize(width: targetWidth, height: targetHeight)
                // set the frame center
                shapeView.center = tapPoint
                // add it
                self.view.addSubview(shapeView)
            }

        } else {
            // Fallback on earlier versions
        }


    }
}

@available(iOS 11.0, *) class MouthShapeView: UIImageView {

    let pointsArray: [CGPoint] = [
        CGPoint(x: 4.0, y: 1.0),
        CGPoint(x: 9.0, y: 1.0),
        CGPoint(x: 13.0, y: 1.0),
        CGPoint(x: 17.0, y: 1.0),
        CGPoint(x: 21.0, y: 1.0),
        CGPoint(x: 26.0, y: 0.0),
        CGPoint(x: 32.0, y: 0.0),
        CGPoint(x: 37.0, y: 1.0),
        CGPoint(x: 33.0, y: 8.0),
        CGPoint(x: 26.0, y: 13.0),
        CGPoint(x: 18.0, y: 15.0),
        CGPoint(x: 10.0, y: 14.0),
        CGPoint(x: 4.0, y: 9.0),
        CGPoint(x: 0.0, y: 2.0),
    ]

    let maskLayer = CAShapeLayer()

    override init(image: UIImage?) {
        super.init(image: image)
        maskLayer.fillColor = UIColor.black.cgColor
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let newPath = UIBezierPath()

        pointsArray.forEach { p in
            if p == pointsArray.first {
                newPath.move(to: p)
            } else {
                newPath.addLine(to: p)
            }
        }

        newPath.close()

        // need to scale the path to self.bounds
        let scaleW = bounds.width / newPath.bounds.width
        let scaleH = bounds.height / newPath.bounds.height

        let trans = CGAffineTransform(scaleX: scaleW, y: scaleH)
        newPath.apply(trans)

        maskLayer.path = newPath.cgPath
        layer.mask = maskLayer

    }

}

When you run that code, and tap on the view, you'll get this:

Really Thanks a lot It is very helpful :) :) – yasmina Apr 06 '20 at 16:11 — yasmina, Apr 06 '20 at 16:11

Mask Image with custom UIBazierPath swift

1 Answers1