A composable type to suplement the read-only CIRectangleFeature.

Quadrilateral.swift

//
//  Quadrilateral.swift
//  CPR
//
//  Created by Joachim Bondo on 16/08/16.
//  Copyright © 2016 Joachim Bondo. All rights reserved.
//

import UIKit
import CoreImage

protocol Quadrilateral: CustomStringConvertible {
	var bounds: CGRect { get }
	var topLeft: CGPoint { get }
	var topRight: CGPoint { get }
	var bottomRight: CGPoint { get }
	var bottomLeft: CGPoint { get }
}

extension Quadrilateral {
	var description: String {
		return "tl {\(String(format: "%.01f", self.topLeft.x)), \(String(format: "%.01f", self.topLeft.y))}, tr {\(String(format: "%.01f", self.topRight.x)), \(String(format: "%.01f", self.topRight.y))}, br {\(String(format: "%.01f", self.bottomRight.x)), \(String(format: "%.01f", self.bottomRight.y))}, bl {\(String(format: "%.01f", self.bottomLeft.x)), \(String(format: "%.01f", self.bottomLeft.y))}"
	}
}

/// Because we cannot instantiate a `CIRectangleFeature` object.
struct QuadrilateralRegion: Quadrilateral {
	
	let topLeft: CGPoint
	let topRight: CGPoint
	let bottomRight: CGPoint
	let bottomLeft: CGPoint
	
	var bounds: CGRect {
		
		let top = max(topLeft.y, topRight.y, bottomRight.y, bottomLeft.y)
		let bottom = min(topLeft.y, topRight.y, bottomRight.y, bottomLeft.y)
		let left = min(topLeft.x, topRight.x, bottomRight.x, bottomLeft.x)
		let right = max(topLeft.x, topRight.x, bottomRight.x, bottomLeft.x)
		
		let origin = CGPoint(x: left, y: bottom)
		let size = CGSize(width: right - left, height: top - bottom)
		
		return CGRect(origin: origin, size: size)
	}
	
	init(topLeft: CGPoint, topRight: CGPoint, bottomRight: CGPoint, bottomLeft: CGPoint) {
		self.topLeft = topLeft
		self.topRight = topRight
		self.bottomRight = bottomRight
		self.bottomLeft = bottomLeft
	}
}

// MARK: - UIKit

extension Quadrilateral {
	
	var path: UIBezierPath {
		let path = UIBezierPath()
		path.move(to: self.topLeft)
		path.addLine(to: self.topRight)
		path.addLine(to: self.bottomRight)
		path.addLine(to: self.bottomLeft)
		path.close()
		return path
	}
}

extension QuadrilateralRegion {
	
	init(rect: CGRect) {
		
		let top = rect.maxY
		let bottom = rect.minY
		let left = rect.minX
		let right = rect.maxX
		
		self.topLeft = CGPoint(x: left, y: top)
		self.topRight = CGPoint(x: right, y: top)
		self.bottomRight = CGPoint(x: right, y: bottom)
		self.bottomLeft = CGPoint(x: left, y: bottom)
	}
}

// MARK: - Core Image

extension CIRectangleFeature: Quadrilateral {}

extension QuadrilateralRegion {
	
	init(rectangleFeature feature: CIRectangleFeature) {
		self.topLeft = feature.topLeft
		self.topRight = feature.topRight
		self.bottomRight = feature.bottomRight
		self.bottomLeft = feature.bottomLeft
	}
}