Tusker/Tusker/Views/ScrollingSegmentedControl.s...

232 lines
9.6 KiB
Swift

//
// ScrollingSegmentedControl.swift
// Tusker
//
// Created by Shadowfacts on 12/11/22.
// Copyright © 2022 Shadowfacts. All rights reserved.
//
import UIKit
class ScrollingSegmentedControl<Value: Hashable>: UIScrollView, UIGestureRecognizerDelegate, UIPointerInteractionDelegate {
private(set) var selectedOption: Value?
var options: [Option] = [] {
didSet {
createOptionViews()
}
}
var didSelectOption: ((Value?) -> Void)?
private let optionsStack = UIStackView()
private let selectedIndicatorView = UIView()
private var selectedIndicatorViewAlignmentConstraints: [NSLayoutConstraint] = []
private var changeSelectionPanRecognizer: UIGestureRecognizer!
private var selectedOptionAtStartOfPan: Value?
private lazy var selectionChangedFeedbackGenerator = UISelectionFeedbackGenerator()
override var intrinsicContentSize: CGSize {
let buttonWidths = optionsStack.arrangedSubviews.map(\.intrinsicContentSize.width).reduce(0, +)
let spacing = (CGFloat(optionsStack.arrangedSubviews.count) - 1) * 8
// add 16 to account for the spacing around optionsStack
return CGSize(width: buttonWidths + spacing + 16, height: 44)
}
override init(frame: CGRect) {
super.init(frame: frame)
showsHorizontalScrollIndicator = false
optionsStack.axis = .horizontal
optionsStack.spacing = 8
optionsStack.distribution = .fillProportionally
optionsStack.translatesAutoresizingMaskIntoConstraints = false
addSubview(optionsStack)
NSLayoutConstraint.activate([
optionsStack.leadingAnchor.constraint(equalTo: contentLayoutGuide.leadingAnchor, constant: 8),
optionsStack.trailingAnchor.constraint(equalTo: contentLayoutGuide.trailingAnchor, constant: -8),
optionsStack.topAnchor.constraint(equalTo: contentLayoutGuide.topAnchor),
optionsStack.bottomAnchor.constraint(equalTo: contentLayoutGuide.bottomAnchor),
optionsStack.heightAnchor.constraint(equalTo: heightAnchor),
// add 16 to account for the spacing around optionsStack
widthAnchor.constraint(lessThanOrEqualTo: optionsStack.widthAnchor, constant: 16),
])
let panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(panRecognized))
self.changeSelectionPanRecognizer = panRecognizer
panRecognizer.delegate = self
optionsStack.addGestureRecognizer(panRecognizer)
optionsStack.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(optionTapped)))
optionsStack.addInteraction(UIPointerInteraction(delegate: self))
self.panGestureRecognizer.delegate = self
selectedIndicatorView.isHidden = true
selectedIndicatorView.backgroundColor = .tintColor
selectedIndicatorView.translatesAutoresizingMaskIntoConstraints = false
addSubview(selectedIndicatorView)
NSLayoutConstraint.activate([
selectedIndicatorView.heightAnchor.constraint(equalToConstant: 4),
selectedIndicatorView.bottomAnchor.constraint(equalTo: contentLayoutGuide.bottomAnchor),
])
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func createOptionViews() {
optionsStack.arrangedSubviews.forEach { $0.removeFromSuperview() }
for (index, option) in options.enumerated() {
let label = UILabel()
label.text = option.name
label.font = .preferredFont(forTextStyle: .headline)
label.adjustsFontForContentSizeCategory = true
label.textColor = .secondaryLabel
label.textAlignment = .center
label.accessibilityTraits = .button
label.accessibilityLabel = "\(option.name), \(index + 1) of \(options.count)"
optionsStack.addArrangedSubview(label)
}
updateSelectedIndicatorView()
invalidateIntrinsicContentSize()
}
func setSelectedOption(_ value: Value, animated: Bool) {
guard selectedOption != value,
options.contains(where: { $0.value == value }) else {
return
}
if selectedOption != nil {
selectionChangedFeedbackGenerator.selectionChanged()
}
selectedOption = value
didSelectOption?(value)
updateSelectedIndicatorView()
if animated && !selectedIndicatorView.isHidden {
let animator = UIViewPropertyAnimator(duration: 0.4, dampingRatio: 0.8) {
self.layoutIfNeeded()
}
animator.startAnimation()
}
}
private func updateSelectedIndicatorView() {
guard let selectedOption,
let selectedIndex = options.firstIndex(where: { $0.value == selectedOption }) else {
selectedIndicatorView.isHidden = true
return
}
let selectedOptionView = optionsStack.arrangedSubviews[selectedIndex]
selectedIndicatorView.isHidden = false
NSLayoutConstraint.deactivate(selectedIndicatorViewAlignmentConstraints)
selectedIndicatorViewAlignmentConstraints = [
selectedIndicatorView.leadingAnchor.constraint(equalTo: selectedOptionView.leadingAnchor),
selectedIndicatorView.trailingAnchor.constraint(equalTo: selectedOptionView.trailingAnchor),
]
NSLayoutConstraint.activate(selectedIndicatorViewAlignmentConstraints)
for (index, optionView) in optionsStack.arrangedSubviews.enumerated() {
let label = optionView as! UILabel
label.textColor = index == selectedIndex ? .label : .secondaryLabel
label.accessibilityTraits = index == selectedIndex ? [.button, .selected] : .button
}
}
// MARK: Interaction
override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
let beganOnSelectedOption: Bool
if let selectedIndex = options.firstIndex(where: { $0.value == selectedOption }),
optionsStack.arrangedSubviews[selectedIndex].frame.contains(self.panGestureRecognizer.location(in: optionsStack)) {
beganOnSelectedOption = true
} else {
beganOnSelectedOption = false
}
// only begin changing selection if the gesutre started on the currently selected item
// otherwise, let the scroll view handle things
if gestureRecognizer == self.changeSelectionPanRecognizer {
return beganOnSelectedOption
} else {
return !beganOnSelectedOption
}
}
@objc private func panRecognized(_ recognizer: UIPanGestureRecognizer) {
let horizontalLocationInStack = CGPoint(x: recognizer.location(in: optionsStack).x, y: 0)
switch recognizer.state {
case .began:
selectedOptionAtStartOfPan = selectedOption
selectionChangedFeedbackGenerator.prepare()
case .changed:
if updateSelectionFor(location: horizontalLocationInStack) {
selectionChangedFeedbackGenerator.prepare()
}
case .ended:
if let selectedOptionAtStartOfPan {
self.selectedOptionAtStartOfPan = nil
if let selectedOption,
selectedOptionAtStartOfPan != selectedOption {
didSelectOption?(selectedOption)
}
}
default:
break
}
}
@objc private func optionTapped(_ recognizer: UITapGestureRecognizer) {
let location = recognizer.location(in: optionsStack)
if updateSelectionFor(location: location) {
didSelectOption?(selectedOption!)
}
}
private func updateSelectionFor(location: CGPoint) -> Bool {
for (index, optionView) in optionsStack.arrangedSubviews.enumerated() where optionView.frame.contains(location) {
if selectedOption != options[index].value {
selectedOption = options[index].value
let animator = UIViewPropertyAnimator(duration: 0.4, dampingRatio: 0.8) {
self.updateSelectedIndicatorView()
self.scrollRectToVisible(optionView.frame.insetBy(dx: -16, dy: 0), animated: false)
self.layoutIfNeeded()
}
animator.startAnimation()
selectionChangedFeedbackGenerator.selectionChanged()
return true
} else {
return false
}
}
return false
}
func pointerInteraction(_ interaction: UIPointerInteraction, regionFor request: UIPointerRegionRequest, defaultRegion: UIPointerRegion) -> UIPointerRegion? {
func distanceToAnyEdge(_ view: UIView) -> CGFloat {
min(abs(view.frame.minX - request.location.x), abs(view.frame.maxX - request.location.x))
}
let (view, index, _) = optionsStack.arrangedSubviews.enumerated().map { ($0.1, $0.0, distanceToAnyEdge($0.1)) }.min(by: { $0.2 < $1.2 })!
return UIPointerRegion(rect: view.frame.insetBy(dx: -8, dy: 0), identifier: index)
}
func pointerInteraction(_ interaction: UIPointerInteraction, styleFor region: UIPointerRegion) -> UIPointerStyle? {
let index = region.identifier as! Int
let optionView = optionsStack.arrangedSubviews[index]
return UIPointerStyle(effect: .hover(UITargetedPreview(view: optionView)))
}
struct Option: Hashable {
let value: Value
let name: String
}
}