Macaw/Source/svg/SVGView.swift

import UIKit

open class SVGView: MacawView {
    
    @IBInspectable open var fileName: String? {
        didSet {
            render()
        }
    }
    
    override open func layoutSubviews() {
        super.layoutSubviews()
        
        render()
    }
    
    private let rootNode = Group()
    private func render() {
        let viewBounds = self.bounds
        let svgNode = SVGParser.parse(
            path: fileName ?? ""
        )
        if let nodeBounds = svgNode.bounds()?.cgRect() {
            let svgWidth = nodeBounds.origin.x + nodeBounds.width
            let svgHeight = nodeBounds.origin.y + nodeBounds.height
            
            let viewAspectRatio = viewBounds.width / viewBounds.height
            let svgAspectRatio = svgWidth / svgHeight
            
            let scaleX = viewBounds.width / svgWidth
            let scaleY = viewBounds.height / svgHeight
            
            switch self.contentMode {
            case .scaleToFill:
                svgNode.place = Transform.scale(
                    sx: Double(scaleX),
                    sy: Double(scaleY)
                )
            case .scaleAspectFill:
                let scaleX, scaleY: CGFloat
                if viewAspectRatio > svgAspectRatio {
                    scaleX = viewBounds.width / svgWidth
                    scaleY = viewBounds.width / (svgWidth / svgAspectRatio)
                } else {
                    scaleX = viewBounds.height / (svgHeight / svgAspectRatio)
                    scaleY = viewBounds.height / svgHeight
                }
                let calculatedWidth = svgWidth * scaleX
                let calculatedHeight = svgHeight * scaleY
                svgNode.place = Transform.move(
                    dx: (viewBounds.width / 2 - calculatedWidth / 2).doubleValue,
                    dy: (viewBounds.height / 2 - calculatedHeight / 2).doubleValue
                ).scale(
                    sx: scaleX.doubleValue,
                    sy: scaleX.doubleValue
                )
            case .scaleAspectFit:
                let calculatedXWidth = scaleX * svgWidth
                let calculatedXHeight = scaleX * svgHeight
                let calculatedYWidth = scaleY * svgWidth
                let calculatedYHeight = scaleY * svgHeight
                
                if calculatedXWidth <= viewBounds.width && calculatedXHeight <= viewBounds.height {
                    svgNode.place = Transform.move(
                        dx: (viewBounds.midX - calculatedXWidth / 2).doubleValue,
                        dy: (viewBounds.midY - calculatedXHeight / 2).doubleValue
                        ).scale(
                            sx: scaleX.doubleValue,
                            sy: scaleX.doubleValue
                    )
                } else if calculatedYWidth <= viewBounds.width && calculatedYHeight <= viewBounds.height {
                    svgNode.place = Transform.move(
                        dx: (viewBounds.midX - calculatedYWidth / 2).doubleValue,
                        dy: (viewBounds.midY - calculatedYHeight / 2).doubleValue
                    ).scale(
                        sx: scaleY.doubleValue,
                        sy: scaleY.doubleValue
                    )
                }
            case .center:
                svgNode.place = Transform.move(
                    dx: getMidX(viewBounds, nodeBounds).doubleValue,
                    dy: getMidY(viewBounds, nodeBounds).doubleValue
                )
            case .top:
                svgNode.place = Transform.move(
                    dx: getMidX(viewBounds, nodeBounds).doubleValue,
                    dy: 0
                )
            case .bottom:
                svgNode.place = Transform.move(
                    dx: getMidX(viewBounds, nodeBounds).doubleValue,
                    dy: getBottom(viewBounds, nodeBounds).doubleValue
                )
            case .left:
                svgNode.place = Transform.move(
                    dx: 0,
                    dy: getMidY(viewBounds, nodeBounds).doubleValue
                )
            case .right:
                svgNode.place = Transform.move(
                    dx: getRight(viewBounds, nodeBounds).doubleValue,
                    dy: getMidY(viewBounds, nodeBounds).doubleValue
                )
            case .topLeft:
                break
            case .topRight:
                svgNode.place = Transform.move(
                    dx: getRight(viewBounds, nodeBounds).doubleValue,
                    dy: 0
                )
            case .bottomLeft:
                svgNode.place = Transform.move(
                    dx: 0,
                    dy: getBottom(viewBounds, nodeBounds).doubleValue
                )
            case .bottomRight:
                svgNode.place = Transform.move(
                    dx: getRight(viewBounds, nodeBounds).doubleValue,
                    dy: getBottom(viewBounds, nodeBounds).doubleValue
                )                
            case .redraw:
                break
            }
        }
        
        rootNode.contents = [svgNode]
        self.node = rootNode
    }
    
    private func getMidX(_ viewBounds: CGRect, _ nodeBounds: CGRect) -> CGFloat {
        let viewMidX = viewBounds.midX
        let nodeMidX = nodeBounds.midX + nodeBounds.origin.x
        return viewMidX - nodeMidX
    }
    
    private func getMidY(_ viewBounds: CGRect, _ nodeBounds: CGRect) -> CGFloat {
        let viewMidY = viewBounds.midY
        let nodeMidY = nodeBounds.midY + nodeBounds.origin.y
        return viewMidY - nodeMidY
    }
    
    private func getBottom(_ viewBounds: CGRect, _ nodeBounds: CGRect) -> CGFloat {
        return viewBounds.maxY - nodeBounds.maxY + nodeBounds.origin.y
    }
    
    private func getRight(_ viewBounds: CGRect, _ nodeBounds: CGRect) -> CGFloat {
        return viewBounds.maxX - nodeBounds.maxX + nodeBounds.origin.x
    }
    
}