如何使 CAShape 层适合 UIImage 视图？

Question

我正在解析 SVG 图像文件并将其路径转换为 ​​CAShapeLayer，之后我将此 CAShapeLayer 添加到 UIImage View 的图层。 它工作正常，但问题是它不适合 UIImage 视图。 那是输出。 Image 1。 这是向 UIImageView 添加图层的代码

        if let svgURL = Bundle.main.url(forResource: "image", withExtension: "svg") {
        let paths = SVGBezierPath.pathsFromSVG(at: svgURL)
        for path in paths {
            items.append(path)
            let layer = createLayer(path: path)
            layer.frame = self.backgroundIV.bounds
            self.backgroundIV.layer.addSublayer(layer)
        }
        
        
    }   // Create Layer from Paths Method


    fileprivate func createLayer(path: SVGBezierPath) -> CAShapeLayer {
    let shapeLayer = CAShapeLayer()
    shapeLayer.path = path.cgPath
    if let any = path.svgAttributes["stroke"] {
        shapeLayer.strokeColor = (any as! CGColor)
    }
    
    if let any = path.svgAttributes["fill"] {
        shapeLayer.fillColor = (any as! CGColor)
    }
    return shapeLayer
}

我搜索并添加了这两行代码，我得到了这个结果

let scale = CGFloat(0.5) 
        for path in paths {
            path.apply(CGAffineTransform(scaleX: scale, y: scale))
            items.append(path)
            let layer = createLayer(path: path)
            layer.frame = self.backgroundIV.bounds
            self.backgroundIV.layer.addSublayer(layer)
        }

这是输出。 Image 2

我不知道如何根据uiImage View bounds计算scaleX或scaleY（在CGAffineTransform方法中使用）值

编辑 注意：我对 CAShapeLayer 应用了触摸支持， 那是代码。

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
    {
        guard let point = touches.first?.location(in: self.backgroundIV),
              let layers = self.backgroundIV.layer.sublayers
        else { return }
        var hitLayers: [CAShapeLayer] = []
        selectedLayer?.lineWidth = CGFloat(0)
        for subLayer in layers {
            if let thisLayer = subLayer as? CAShapeLayer,
               let pth = thisLayer.path {
                let layerPoint: CGPoint = thisLayer.convert(point, from: self.backgroundIV.layer)
                if pth.contains(layerPoint) {
//                    undoModel.append()
                    hitLayers.append(thisLayer)
                }
            }
        }
        
        selectedLayer = hitLayers.last
        selectedLayer?.strokeColor = UIColor.red.cgColor
        selectedLayer?.lineWidth = CGFloat(3)
        undo.append(.init(stokeColor: nil, selectedLayer: selectedLayer, points: []))
        
        if ((selectedLayer?.frame.contains(point)) != nil) {
            isDragged = true
        }
    }

Answer 1

根据您更新的问题，使用视图边界计算比例

var paths = [SVGBezierPath]()

override func viewDidLoad() {
    super.viewDidLoad()

    if let svgURL = Bundle.main.url(forResource: "Freesample", withExtension: "svg") {
        paths = SVGBezierPath.pathsFromSVG(at: svgURL)
        backgroundIV.layer.borderColor = UIColor.black.withAlphaComponent(0.3).cgColor
        backgroundIV.layer.borderWidth = 1
    }
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    let svgBounds = SVGBoundingRectForPaths(paths)
    var scale = CGFloat.zero
    if backgroundIV.bounds.width < backgroundIV.bounds.height {
        scale = backgroundIV.bounds.width / svgBounds.width
    } else {
        scale = backgroundIV.bounds.height / svgBounds.height
    }
    
    self.backgroundIV.layer.sublayers?.forEach { $0.removeFromSuperlayer() }
    for path in paths {
        path.apply(.init(scaleX: scale, y: scale))
        let layer = createLayer(path: path)
        layer.frame = self.backgroundIV.bounds
        self.backgroundIV.layer.addSublayer(layer)
    }
}

Answer 2

这与我在上一个关于检测多层触摸的问题中给出的答案基本相同。

不同之处在于，此示例使用SVGImageView，而不是使用您的代码来创建/添加图层，它是PocketSVG 的一部分：

class BoxesViewController: UIViewController {
    
    var backgroundIV: SVGImageView!
    
    var detectMode: DetectMode = .All
    var detectType: DetectType = .ShapePath
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .systemYellow
        
        guard let svgURL = Bundle.main.url(forResource: "roundedboxes", withExtension: "svg") else {
            fatalError("SVG file not found!!!")
        }
        
        backgroundIV = SVGImageView.init(contentsOf: svgURL)
        
        backgroundIV.frame = view.bounds
        backgroundIV.contentMode = .scaleAspectFit
        backgroundIV.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        
        
        let modeControl = UISegmentedControl(items: ["All", "Top Most", "Bottom Most"])
        let typeControl = UISegmentedControl(items: ["Shape Path", "Shape Bounding Box"])
        
        modeControl.translatesAutoresizingMaskIntoConstraints = false
        typeControl.translatesAutoresizingMaskIntoConstraints = false
        backgroundIV.translatesAutoresizingMaskIntoConstraints = false
        
        view.addSubview(modeControl)
        view.addSubview(typeControl)
        view.addSubview(backgroundIV)
        
        let g = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            
            modeControl.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
            modeControl.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            modeControl.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -40.0),
            
            typeControl.topAnchor.constraint(equalTo: modeControl.bottomAnchor, constant: 40.0),
            typeControl.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            typeControl.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -40.0),
            
            backgroundIV.topAnchor.constraint(equalTo: typeControl.bottomAnchor, constant: 40.0),
            backgroundIV.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            backgroundIV.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -40.0),
            backgroundIV.heightAnchor.constraint(equalTo: backgroundIV.widthAnchor),
            
        ])
        
        modeControl.addTarget(self, action: #selector(modeChanged(_:)), for: .valueChanged)
        typeControl.addTarget(self, action: #selector(typeChanged(_:)), for: .valueChanged)
        
        modeControl.selectedSegmentIndex = 0
        typeControl.selectedSegmentIndex = 0
        
        // so we can see the frame of the image view
        backgroundIV.backgroundColor = .white
        
    }
    
    @objc func modeChanged(_ sender: UISegmentedControl) -> Void {
        switch sender.selectedSegmentIndex {
        case 0:
            detectMode = .All
        case 1:
            detectMode = .TopMost
        case 2:
            detectMode = .BottomMost
        default:
            ()
        }
    }
    
    @objc func typeChanged(_ sender: UISegmentedControl) -> Void {
        switch sender.selectedSegmentIndex {
        case 0:
            detectType = .ShapePath
        case 1:
            detectType = .ShapeBounds
        default:
            ()
        }
    }
    
    fileprivate func createLayer(path: SVGBezierPath) -> CAShapeLayer {
        let shapeLayer = CAShapeLayer()
        shapeLayer.path = path.cgPath
        if let any = path.svgAttributes["stroke"] {
            shapeLayer.strokeColor = (any as! CGColor)
        }
        
        if let any = path.svgAttributes["fill"] {
            shapeLayer.fillColor = (any as! CGColor)
        }
        return shapeLayer
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        guard let point = touches.first?.location(in: self.backgroundIV),
              // make sure backgroundIV has sublayers
              let layers = self.backgroundIV.layer.sublayers
        else { return }
        
        var hitLayers: [CAShapeLayer] = []
        
        // loop through all sublayers
        for subLayer in layers {
            // make sure
            //  it is a CAShapeLayer
            //  it has a path
            if let thisLayer = subLayer as? CAShapeLayer,
               let pth = thisLayer.path {
                // clear the lineWidth... we'll reset it after getting the hit layers
                thisLayer.lineWidth = 0
                
                // convert touch point from backgroundIV.layer to thisLayer
                let layerPoint: CGPoint = thisLayer.convert(point, from: self.backgroundIV.layer)
                
                if detectType == .ShapePath {
                    // does the path contain the point?
                    if pth.contains(layerPoint) {
                        hitLayers.append(thisLayer)
                    }
                } else if detectType == .ShapeBounds {
                    if pth.boundingBox.contains(layerPoint) {
                        hitLayers.append(thisLayer)
                    }
                }
            }
        }
        
        if detectMode == .All {
            hitLayers.forEach { layer in
                layer.strokeColor = UIColor.cyan.cgColor
                layer.lineWidth = 3
            }
        } else if detectMode == .TopMost {
            if let layer = hitLayers.last {
                layer.strokeColor = UIColor.cyan.cgColor
                layer.lineWidth = 3
            }
        } else if detectMode == .BottomMost {
            if let layer = hitLayers.first {
                layer.strokeColor = UIColor.cyan.cgColor
                layer.lineWidth = 3
            }
        }
        
    }
    
}

现在 SVG 文件被缩放以适应视图：