/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Defines a `CascadingLayout` that allows you to lay out content diagonally.

*/

import CoreGraphics

/// A layout that diagonally lays out its children.

struct CascadingLayout<Child: Layout>: Layout {

    typealias Content = Child.Content

    var children: [Child]

    var overlapFactor: CGFloat

    init(children: [Child], overlapFactor: CGFloat = 0.2) {

        self.children = children

        self.overlapFactor = overlapFactor

    }

    mutating func layout(in rect: CGRect) {

        let childSizeFactor = 1.0 / (1.0 + overlapFactor * CGFloat(children.count - 1))

        var childRect = rect

        childRect.size.width *= childSizeFactor

        childRect.size.height *= childSizeFactor

        for index in children.indices {

            children[index].layout(in: childRect)

            childRect.origin.x += childRect.size.width * overlapFactor

            childRect.origin.y += childRect.size.height * overlapFactor

        }

    }

    var contents: [Content] {

        return children.flatMap { $0.contents }

    }

}