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lockdown-iOS-mirror/LockdowniOS/Align.swift
2020-10-02 23:03:16 +03:00

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// The MIT License (MIT)
//
// Copyright (c) 2017-2020 Alexander Grebenyuk (github.com/kean).
#if os(iOS) || os(tvOS)
import UIKit
internal protocol LayoutItem { // `UIView`, `UILayoutGuide`
var superview: UIView? { get }
}
extension UIView: LayoutItem {}
extension UILayoutGuide: LayoutItem {
internal var superview: UIView? { owningView }
}
#elseif os(macOS)
import AppKit
internal protocol LayoutItem { // `NSView`, `NSLayoutGuide`
var superview: NSView? { get }
}
extension NSView: LayoutItem {}
extension NSLayoutGuide: LayoutItem {
internal var superview: NSView? { owningView }
}
#endif
internal extension LayoutItem { // Align methods are available via `LayoutAnchors`
@nonobjc var anchors: LayoutAnchors<Self> { LayoutAnchors(base: self) }
}
// MARK: - LayoutAnchors
internal struct LayoutAnchors<Base> {
internal let base: Base
}
internal extension LayoutAnchors where Base: LayoutItem {
// MARK: Anchors
var top: Anchor<AnchorType.Edge, AnchorAxis.Vertical> { Anchor(base, .top) }
var bottom: Anchor<AnchorType.Edge, AnchorAxis.Vertical> { Anchor(base, .bottom) }
var left: Anchor<AnchorType.Edge, AnchorAxis.Horizontal> { Anchor(base, .left) }
var right: Anchor<AnchorType.Edge, AnchorAxis.Horizontal> { Anchor(base, .right) }
var leading: Anchor<AnchorType.Edge, AnchorAxis.Horizontal> { Anchor(base, .leading) }
var trailing: Anchor<AnchorType.Edge, AnchorAxis.Horizontal> { Anchor(base, .trailing) }
var centerX: Anchor<AnchorType.Center, AnchorAxis.Horizontal> { Anchor(base, .centerX) }
var centerY: Anchor<AnchorType.Center, AnchorAxis.Vertical> { Anchor(base, .centerY) }
var firstBaseline: Anchor<AnchorType.Baseline, AnchorAxis.Vertical> { Anchor(base, .firstBaseline) }
var lastBaseline: Anchor<AnchorType.Baseline, AnchorAxis.Vertical> { Anchor(base, .lastBaseline) }
var width: Anchor<AnchorType.Dimension, AnchorAxis.Horizontal> { Anchor(base, .width) }
var height: Anchor<AnchorType.Dimension, AnchorAxis.Vertical> { Anchor(base, .height) }
// MARK: Anchor Collections
var edges: AnchorCollectionEdges { AnchorCollectionEdges(item: base) }
var center: AnchorCollectionCenter { AnchorCollectionCenter(x: centerX, y: centerY) }
var size: AnchorCollectionSize { AnchorCollectionSize(width: width, height: height) }
}
#if os(iOS) || os(tvOS)
internal extension LayoutAnchors where Base: UIView {
var margins: LayoutAnchors<UILayoutGuide> { base.layoutMarginsGuide.anchors }
var safeArea: LayoutAnchors<UILayoutGuide> { base.safeAreaLayoutGuide.anchors }
}
#endif
// MARK: - Anchors
// phantom types
internal enum AnchorAxis {
internal class Horizontal {}
internal class Vertical {}
}
internal enum AnchorType {
internal class Dimension {}
internal class Alignment {}
internal class Center: Alignment {}
internal class Edge: Alignment {}
internal class Baseline: Alignment {}
}
/// An anchor represents one of the view's layout attributes (e.g. `left`,
/// `centerX`, `width`, etc). Use the anchors methods to construct constraints.
internal struct Anchor<Type, Axis> { // type and axis are phantom types
fileprivate let item: LayoutItem
fileprivate let attribute: NSLayoutConstraint.Attribute
fileprivate let offset: CGFloat
fileprivate let multiplier: CGFloat
fileprivate init(_ item: LayoutItem, _ attribute: NSLayoutConstraint.Attribute, offset: CGFloat = 0, multiplier: CGFloat = 1) {
self.item = item; self.attribute = attribute; self.offset = offset; self.multiplier = multiplier
}
/// Returns a new anchor offset by a given amount.
///
/// - note: Consider using a convenience operator instead: `view.anchors.top + 10`.
internal func offsetting(by offset: CGFloat) -> Anchor<Type, Axis> {
Anchor<Type, Axis>(item, attribute, offset: self.offset + offset, multiplier: self.multiplier)
}
/// Returns a new anchor with a given multiplier.
///
/// - note: Consider using a convenience operator instead: `view.anchors.height * 2`.
internal func multiplied(by multiplier: CGFloat) -> Anchor<Type, Axis> {
Anchor<Type, Axis>(item, attribute, offset: self.offset * multiplier, multiplier: self.multiplier * multiplier)
}
}
internal func + <Type, Axis>(anchor: Anchor<Type, Axis>, offset: CGFloat) -> Anchor<Type, Axis> {
anchor.offsetting(by: offset)
}
internal func - <Type, Axis>(anchor: Anchor<Type, Axis>, offset: CGFloat) -> Anchor<Type, Axis> {
anchor.offsetting(by: -offset)
}
internal func * <Type, Axis>(anchor: Anchor<Type, Axis>, multiplier: CGFloat) -> Anchor<Type, Axis> {
anchor.multiplied(by: multiplier)
}
// MARK: - Anchors (AnchorType.Alignment)
internal extension Anchor where Type: AnchorType.Alignment {
@discardableResult func equal<Type: AnchorType.Alignment>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .equal)
}
@discardableResult func greaterThanOrEqual<Type: AnchorType.Alignment>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .greaterThanOrEqual)
}
@discardableResult func lessThanOrEqual<Type: AnchorType.Alignment>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .lessThanOrEqual)
}
}
// MARK: - Anchors (AnchorType.Dimension)
internal extension Anchor where Type: AnchorType.Dimension {
@discardableResult func equal<Type: AnchorType.Dimension, Axis>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .equal)
}
@discardableResult func greaterThanOrEqual<Type: AnchorType.Dimension, Axis>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .greaterThanOrEqual)
}
@discardableResult func lessThanOrEqual<Type: AnchorType.Dimension, Axis>(_ anchor: Anchor<Type, Axis>, constant: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, anchor, constant: constant, relation: .lessThanOrEqual)
}
}
// MARK: - Anchors (AnchorType.Dimension)
extension Anchor where Type: AnchorType.Dimension {
@discardableResult internal func equal(_ constant: CGFloat) -> NSLayoutConstraint {
Constraints.constrain(item: item, attribute: attribute, relatedBy: .equal, constant: constant)
}
@discardableResult internal func greaterThanOrEqual(_ constant: CGFloat) -> NSLayoutConstraint {
Constraints.constrain(item: item, attribute: attribute, relatedBy: .greaterThanOrEqual, constant: constant)
}
@discardableResult internal func lessThanOrEqual(_ constant: CGFloat) -> NSLayoutConstraint {
Constraints.constrain(item: item, attribute: attribute, relatedBy: .lessThanOrEqual, constant: constant)
}
}
// MARK: - Anchors (AnchorType.Edge)
extension Anchor where Type: AnchorType.Edge {
/// Pins the edge to the respected edges of the given container.
@discardableResult internal func pin(to container: LayoutItem? = nil, inset: CGFloat = 0) -> NSLayoutConstraint {
let isInverted = [.trailing, .right, .bottom].contains(attribute)
return Constraints.constrain(self, toItem: container ?? item.superview!, attribute: attribute, constant: (isInverted ? -inset : inset))
}
/// Adds spacing between the current anchors.
@discardableResult internal func spacing<Type: AnchorType.Edge>(_ spacing: CGFloat, to anchor: Anchor<Type, Axis>, relation: NSLayoutConstraint.Relation = .equal) -> NSLayoutConstraint {
let isInverted = (attribute == .bottom && anchor.attribute == .top) ||
(attribute == .right && anchor.attribute == .left) ||
(attribute == .trailing && anchor.attribute == .leading)
return Constraints.constrain(self, anchor, constant: isInverted ? -spacing : spacing, relation: isInverted ? relation.inverted : relation)
}
}
// MARK: - Anchors (AnchorType.Center)
extension Anchor where Type: AnchorType.Center {
/// Aligns the axis with a superview axis.
@discardableResult internal func align(offset: CGFloat = 0) -> NSLayoutConstraint {
Constraints.constrain(self, toItem: item.superview!, attribute: attribute, constant: offset)
}
}
// MARK: - AnchorCollectionEdges
internal struct Alignmment {
internal enum Horizontal {
case fill, center, leading, trailing
}
internal enum Vertical {
case fill, center, top, bottom
}
internal let horizontal: Horizontal
internal let vertical: Vertical
internal init(horizontal: Horizontal, vertical: Vertical) {
(self.horizontal, self.vertical) = (horizontal, vertical)
}
internal static let fill = Alignmment(horizontal: .fill, vertical: .fill)
internal static let center = Alignmment(horizontal: .center, vertical: .center)
internal static let topLeading = Alignmment(horizontal: .leading, vertical: .top)
internal static let leading = Alignmment(horizontal: .leading, vertical: .fill)
internal static let bottomLeading = Alignmment(horizontal: .leading, vertical: .bottom)
internal static let bottom = Alignmment(horizontal: .fill, vertical: .bottom)
internal static let bottomTrailing = Alignmment(horizontal: .trailing, vertical: .bottom)
internal static let trailing = Alignmment(horizontal: .trailing, vertical: .fill)
internal static let topTrailing = Alignmment(horizontal: .trailing, vertical: .top)
internal static let top = Alignmment(horizontal: .fill, vertical: .top)
}
internal struct AnchorCollectionEdges {
fileprivate let item: LayoutItem
fileprivate var isAbsolute = false
// By default, edges use locale-specific `.leading` and `.trailing`
internal func absolute() -> AnchorCollectionEdges {
AnchorCollectionEdges(item: item, isAbsolute: true)
}
#if os(iOS) || os(tvOS)
internal typealias Axis = NSLayoutConstraint.Axis
#else
internal typealias Axis = NSLayoutConstraint.Orientation
#endif
@discardableResult internal func pin(to item2: LayoutItem? = nil, insets: EdgeInsets = .zero, axis: Axis? = nil, alignment: Alignmment = .fill) -> [NSLayoutConstraint] {
let item2 = item2 ?? item.superview!
let left: NSLayoutConstraint.Attribute = isAbsolute ? .left : .leading
let right: NSLayoutConstraint.Attribute = isAbsolute ? .right : .trailing
var constraints = [NSLayoutConstraint]()
func constrain(attribute: NSLayoutConstraint.Attribute, relation: NSLayoutConstraint.Relation, constant: CGFloat) {
constraints.append(Constraints.constrain(item: item, attribute: attribute, relatedBy: relation, toItem: item2, attribute: attribute, multiplier: 1, constant: constant))
}
if axis == nil || axis == .horizontal {
constrain(attribute: left, relation: alignment.horizontal == .fill || alignment.horizontal == .leading ? .equal : .greaterThanOrEqual, constant: insets.left)
constrain(attribute: right, relation: alignment.horizontal == .fill || alignment.horizontal == .trailing ? .equal : .lessThanOrEqual, constant: -insets.right)
if alignment.horizontal == .center {
constrain(attribute: .centerX, relation: .equal, constant: 0)
}
}
if axis == nil || axis == .vertical {
constrain(attribute: .top, relation: alignment.vertical == .fill || alignment.vertical == .top ? .equal : .greaterThanOrEqual, constant: insets.top)
constrain(attribute: .bottom, relation: alignment.vertical == .fill || alignment.vertical == .bottom ? .equal : .lessThanOrEqual, constant: -insets.bottom)
if alignment.vertical == .center {
constrain(attribute: .centerY, relation: .equal, constant: 0)
}
}
return constraints
}
}
// MARK: - AnchorCollectionCenter
internal struct AnchorCollectionCenter {
fileprivate let x: Anchor<AnchorType.Center, AnchorAxis.Horizontal>
fileprivate let y: Anchor<AnchorType.Center, AnchorAxis.Vertical>
/// Centers the view in the superview.
@discardableResult internal func align() -> [NSLayoutConstraint] {
[x.align(), y.align()]
}
/// Makes the axis equal to the other collection of axis.
@discardableResult internal func align<Item: LayoutItem>(with item: Item) -> [NSLayoutConstraint] {
[x.equal(item.anchors.centerX), y.equal(item.anchors.centerY)]
}
}
// MARK: - AnchorCollectionSize
internal struct AnchorCollectionSize {
fileprivate let width: Anchor<AnchorType.Dimension, AnchorAxis.Horizontal>
fileprivate let height: Anchor<AnchorType.Dimension, AnchorAxis.Vertical>
/// Set the size of item.
@discardableResult internal func equal(_ size: CGSize) -> [NSLayoutConstraint] {
[width.equal(size.width), height.equal(size.height)]
}
/// Set the size of item.
@discardableResult internal func greaterThanOrEqul(_ size: CGSize) -> [NSLayoutConstraint] {
[width.greaterThanOrEqual(size.width), height.greaterThanOrEqual(size.height)]
}
/// Set the size of item.
@discardableResult internal func lessThanOrEqual(_ size: CGSize) -> [NSLayoutConstraint] {
[width.lessThanOrEqual(size.width), height.lessThanOrEqual(size.height)]
}
/// Makes the size of the item equal to the size of the other item.
@discardableResult internal func equal<Item: LayoutItem>(_ item: Item, insets: CGSize = .zero, multiplier: CGFloat = 1) -> [NSLayoutConstraint] {
[width.equal(item.anchors.width * multiplier - insets.width), height.equal(item.anchors.height * multiplier - insets.height)]
}
@discardableResult internal func greaterThanOrEqual<Item: LayoutItem>(_ item: Item, insets: CGSize = .zero, multiplier: CGFloat = 1) -> [NSLayoutConstraint] {
[width.greaterThanOrEqual(item.anchors.width * multiplier - insets.width), height.greaterThanOrEqual(item.anchors.height * multiplier - insets.height)]
}
@discardableResult internal func lessThanOrEqual<Item: LayoutItem>(_ item: Item, insets: CGSize = .zero, multiplier: CGFloat = 1) -> [NSLayoutConstraint] {
[width.lessThanOrEqual(item.anchors.width * multiplier - insets.width), height.lessThanOrEqual(item.anchors.height * multiplier - insets.height)]
}
}
// MARK: - Constraints
internal final class Constraints {
/// Returns all of the created constraints.
internal private(set) var constraints = [NSLayoutConstraint]()
/// All of the constraints created in the given closure are automatically
/// activated at the same time. This is more efficient then installing them
/// one-be-one. More importantly, it allows to make changes to the constraints
/// before they are installed (e.g. change `priority`).
///
/// - parameter activate: Set to `false` to disable automatic activation of
/// constraints.
@discardableResult internal init(activate: Bool = true, _ closure: () -> Void) {
Constraints._stack.append(self)
closure() // create constraints
Constraints._stack.removeLast()
if activate { NSLayoutConstraint.activate(constraints) }
}
/// Creates and automatically installs a constraint.
fileprivate static func constrain(item item1: Any, attribute attr1: NSLayoutConstraint.Attribute, relatedBy relation: NSLayoutConstraint.Relation = .equal, toItem item2: Any? = nil, attribute attr2: NSLayoutConstraint.Attribute? = nil, multiplier: CGFloat = 1, constant: CGFloat = 0) -> NSLayoutConstraint {
precondition(Thread.isMainThread, "Align APIs can only be used from the main thread")
#if os(iOS) || os(tvOS)
(item1 as? UIView)?.translatesAutoresizingMaskIntoConstraints = false
#elseif os(macOS)
(item1 as? NSView)?.translatesAutoresizingMaskIntoConstraints = false
#endif
let constraint = NSLayoutConstraint(item: item1, attribute: attr1, relatedBy: relation, toItem: item2, attribute: attr2 ?? .notAnAttribute, multiplier: multiplier, constant: constant)
_install(constraint)
return constraint
}
/// Creates and automatically installs a constraint between two anchors.
fileprivate static func constrain<T1, A1, T2, A2>(_ lhs: Anchor<T1, A1>, _ rhs: Anchor<T2, A2>, constant: CGFloat = 0, multiplier: CGFloat = 1, relation: NSLayoutConstraint.Relation = .equal) -> NSLayoutConstraint {
constrain(item: lhs.item, attribute: lhs.attribute, relatedBy: relation, toItem: rhs.item, attribute: rhs.attribute, multiplier: (multiplier / lhs.multiplier) * rhs.multiplier, constant: constant - lhs.offset + rhs.offset)
}
/// Creates and automatically installs a constraint between an anchor and
/// a given item.
fileprivate static func constrain<T1, A1>(_ lhs: Anchor<T1, A1>, toItem item2: Any?, attribute attr2: NSLayoutConstraint.Attribute?, constant: CGFloat = 0, multiplier: CGFloat = 1, relation: NSLayoutConstraint.Relation = .equal) -> NSLayoutConstraint {
constrain(item: lhs.item, attribute: lhs.attribute, relatedBy: relation, toItem: item2, attribute: attr2, multiplier: multiplier / lhs.multiplier, constant: constant - lhs.offset)
}
private static var _stack = [Constraints]() // this is what enabled constraint auto-installing
private static func _install(_ constraint: NSLayoutConstraint) {
if let group = _stack.last {
group.constraints.append(constraint)
} else {
constraint.isActive = true
}
}
}
extension Constraints {
@discardableResult internal convenience init<A: LayoutItem>(for a: A, _ closure: (LayoutAnchors<A>) -> Void) {
self.init { closure(a.anchors) }
}
@discardableResult internal convenience init<A: LayoutItem, B: LayoutItem>(for a: A, _ b: B, _ closure: (LayoutAnchors<A>, LayoutAnchors<B>) -> Void) {
self.init { closure(a.anchors, b.anchors) }
}
@discardableResult internal convenience init<A: LayoutItem, B: LayoutItem, C: LayoutItem>(for a: A, _ b: B, _ c: C, _ closure: (LayoutAnchors<A>, LayoutAnchors<B>, LayoutAnchors<C>) -> Void) {
self.init { closure(a.anchors, b.anchors, c.anchors) }
}
@discardableResult internal convenience init<A: LayoutItem, B: LayoutItem, C: LayoutItem, D: LayoutItem>(for a: A, _ b: B, _ c: C, _ d: D, _ closure: (LayoutAnchors<A>, LayoutAnchors<B>, LayoutAnchors<C>, LayoutAnchors<D>) -> Void) {
self.init { closure(a.anchors, b.anchors, c.anchors, d.anchors) }
}
}
// MARK: - Misc
#if os(iOS) || os(tvOS)
internal typealias EdgeInsets = UIEdgeInsets
#elseif os(macOS)
internal typealias EdgeInsets = NSEdgeInsets
internal extension NSEdgeInsets {
static let zero = NSEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
}
#endif
extension NSLayoutConstraint.Relation {
fileprivate var inverted: NSLayoutConstraint.Relation {
switch self {
case .greaterThanOrEqual: return .lessThanOrEqual
case .lessThanOrEqual: return .greaterThanOrEqual
case .equal: return self
@unknown default: return self
}
}
}
extension EdgeInsets {
fileprivate func inset(for attribute: NSLayoutConstraint.Attribute, edge: Bool = false) -> CGFloat {
switch attribute {
case .top: return top; case .bottom: return edge ? -bottom : bottom
case .left, .leading: return left
case .right, .trailing: return edge ? -right : right
default: return 0
}
}
}
// MARK: - Extensions
extension Anchor where Type: AnchorType.Edge {
@discardableResult internal func safeAreaPin(inset: CGFloat = 0) -> NSLayoutConstraint {
pin(to: item.superview!.safeAreaLayoutGuide, inset: inset)
}
@discardableResult internal func readableContentPin(inset: CGFloat = 0) -> NSLayoutConstraint {
pin(to: item.superview!.readableContentGuide, inset: inset)
}
@discardableResult internal func marginsPin(inset: CGFloat = 0) -> NSLayoutConstraint {
pin(to: item.superview!.layoutMarginsGuide, inset: inset)
}
}
extension AnchorCollectionEdges {
@discardableResult internal func safeAreaPin(insets: EdgeInsets = .zero, axis: Axis? = nil, alignment: Alignmment = .fill) -> [NSLayoutConstraint] {
pin(to: item.superview!.safeAreaLayoutGuide, insets: insets, axis: axis, alignment: alignment)
}
@discardableResult internal func readableContentPin(insets: EdgeInsets = .zero, axis: Axis? = nil, alignment: Alignmment = .fill) -> [NSLayoutConstraint] {
pin(to: item.superview!.readableContentGuide, insets: insets, axis: axis, alignment: alignment)
}
@discardableResult internal func marginsPin(insets: EdgeInsets = .zero, axis: Axis? = nil, alignment: Alignmment = .fill) -> [NSLayoutConstraint] {
pin(to: item.superview!.layoutMarginsGuide, insets: insets, axis: axis, alignment: alignment)
}
}