Path: blob/main/SignalUI/Stickers/StickerHorizontalListView.swift
1 views
//
// Copyright 2019 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
//
public import SignalServiceKit
public protocol StickerHorizontalListViewItem {
var view: UIView { get }
var didSelectBlock: () -> Void { get }
var isSelected: Bool { get }
var accessibilityName: String { get }
}
// MARK: -
public class StickerHorizontalListViewItemSticker: StickerHorizontalListViewItem {
private let stickerInfo: StickerInfo
public let didSelectBlock: () -> Void
public let isSelectedBlock: () -> Bool
private weak var cache: StickerViewCache?
// This initializer can be used for cells which are never selected.
public convenience init(
stickerInfo: StickerInfo,
didSelectBlock: @escaping () -> Void,
cache: StickerViewCache? = nil,
) {
self.init(stickerInfo: stickerInfo, didSelectBlock: didSelectBlock, isSelectedBlock: { false }, cache: cache)
}
public init(
stickerInfo: StickerInfo,
didSelectBlock: @escaping () -> Void,
isSelectedBlock: @escaping () -> Bool,
cache: StickerViewCache? = nil,
) {
self.stickerInfo = stickerInfo
self.didSelectBlock = didSelectBlock
self.isSelectedBlock = isSelectedBlock
self.cache = cache
}
private func reusableStickerView(forStickerInfo stickerInfo: StickerInfo) -> StickerReusableView {
let view: StickerReusableView = {
if let view = cache?.object(forKey: stickerInfo) { return view }
let view = StickerReusableView()
cache?.setObject(view, forKey: stickerInfo)
return view
}()
guard !view.hasStickerView else { return view }
guard let stickerView = StickerView.stickerView(forInstalledStickerInfo: stickerInfo) else {
view.showPlaceholder()
return view
}
stickerView.layer.minificationFilter = .trilinear
view.configure(with: stickerView)
return view
}
public var view: UIView { reusableStickerView(forStickerInfo: stickerInfo) }
public var isSelected: Bool {
return isSelectedBlock()
}
public var accessibilityName: String {
// We just need a stable identifier.
return "pack." + stickerInfo.asKey()
}
}
// MARK: -
public class StickerHorizontalListViewItemRecents: StickerHorizontalListViewItem {
public let didSelectBlock: () -> Void
public let isSelectedBlock: () -> Bool
public init(
didSelectBlock: @escaping () -> Void,
isSelectedBlock: @escaping () -> Bool,
) {
self.didSelectBlock = didSelectBlock
self.isSelectedBlock = isSelectedBlock
}
public var view: UIView {
let imageView = UIImageView(image: UIImage(named: "recent"))
imageView.tintColor = .Signal.label
return imageView
}
public var isSelected: Bool {
return isSelectedBlock()
}
public var accessibilityName: String {
return "recents"
}
}
// MARK: -
public class StickerHorizontalListView: UICollectionView {
private let cellSize: CGFloat
private let cellContentInset: CGFloat
public typealias Item = StickerHorizontalListViewItem
public var items = [Item]() {
didSet {
AssertIsOnMainThread()
collectionViewLayout.invalidateLayout()
reloadData()
}
}
private var cellRegistration: UICollectionView.CellRegistration<UICollectionViewCell, Item>!
public init(cellSize: CGFloat, cellContentInset: CGFloat, spacing: CGFloat) {
self.cellSize = cellSize
self.cellContentInset = cellContentInset
let layout = LinearHorizontalLayout(
configuration: .init(itemSize: CGSize(square: cellSize), minimumInteritemSpacing: spacing),
)
super.init(frame: .zero, collectionViewLayout: layout)
cellRegistration = UICollectionView.CellRegistration<UICollectionViewCell, Item> { cell, indexPath, item in
// Remove previous content.
cell.contentView.removeAllSubviews()
// Add custom view to the cell.
let itemView = item.view
itemView.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.addSubview(itemView)
NSLayoutConstraint.activate([
itemView.topAnchor.constraint(equalTo: cell.contentView.topAnchor, constant: cellContentInset),
itemView.leadingAnchor.constraint(equalTo: cell.contentView.leadingAnchor, constant: cellContentInset),
itemView.trailingAnchor.constraint(equalTo: cell.contentView.trailingAnchor, constant: -cellContentInset),
itemView.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor, constant: -cellContentInset),
])
// Configure background - this closure is called whenever cell state changes.
cell.configurationUpdateHandler = { cell, state in
var background = UIBackgroundConfiguration.clear()
background.cornerRadius = cellSize / 2
if item.isSelected {
background.backgroundColor = .Signal.MaterialBase.button
} else {
background.backgroundColor = .clear
}
cell.backgroundConfiguration = background
}
}
backgroundColor = .clear
delegate = self
dataSource = self
showsHorizontalScrollIndicator = false
setContentHuggingHorizontalLow()
setCompressionResistanceHorizontalLow()
}
public required init(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
// Reload visible items to refresh the "selected" state
func updateSelections(scrollToSelectedItem: Bool = false) {
reloadData()
guard scrollToSelectedItem else { return }
guard let (selectedIndex, _) = items.enumerated().first(where: { $1.isSelected }) else { return }
scrollToItem(at: IndexPath(row: selectedIndex, section: 0), at: .centeredHorizontally, animated: true)
}
}
// MARK: - UICollectionViewDelegate
extension StickerHorizontalListView: UICollectionViewDelegate {
public func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
guard let item = items[safe: indexPath.row] else {
owsFailDebug("Invalid index path: \(indexPath)")
return
}
item.didSelectBlock()
reloadItems(at: [indexPath])
}
}
// MARK: - UICollectionViewDataSource
extension StickerHorizontalListView: UICollectionViewDataSource {
public func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection sectionIdx: Int) -> Int {
return items.count
}
public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
guard let item = items[safe: indexPath.row] else {
owsFailDebug("Invalid index path: \(indexPath)")
return UICollectionViewCell()
}
return collectionView.dequeueConfiguredReusableCell(
using: cellRegistration,
for: indexPath,
item: item,
)
}
}
// A trivial layout that places each item in a horizontal line.
// Each item has uniform size.
private class LinearHorizontalLayout: UICollectionViewLayout {
struct Configuration {
var itemSize: CGSize
var itemSpacing: CGFloat
init(
itemSize: CGSize,
minimumInteritemSpacing: CGFloat = 8,
) {
self.itemSize = itemSize
self.itemSpacing = minimumInteritemSpacing
}
}
// MARK: - Properties
private let configuration: Configuration
private var cachedAttributes: [UICollectionViewLayoutAttributes] = []
private var contentWidth: CGFloat = 0
override var flipsHorizontallyInOppositeLayoutDirection: Bool {
true
}
override var collectionViewContentSize: CGSize {
guard let collectionView else { return .zero }
return CGSize(
width: contentWidth,
height: collectionView.bounds.height - collectionView.contentInset.totalHeight,
)
}
// MARK: Initializers
@available(*, unavailable, message: "use other constructor instead.")
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
init(configuration: Configuration) {
self.configuration = configuration
super.init()
}
// MARK: Methods
override func invalidateLayout() {
super.invalidateLayout()
cachedAttributes.removeAll()
contentWidth = 0
}
override func invalidateLayout(with context: UICollectionViewLayoutInvalidationContext) {
super.invalidateLayout(with: context)
cachedAttributes.removeAll()
contentWidth = 0
}
override func prepare() {
super.prepare()
guard let collectionView, cachedAttributes.isEmpty else { return }
guard collectionView.numberOfSections == 1 else {
owsFailDebug("This layout only support a single section.")
return
}
let itemCount = collectionView.numberOfItems(inSection: 0)
guard itemCount > 0 else { return }
let itemSize = configuration.itemSize
let spacing = configuration.itemSpacing
// Calculate vertical centering
let collectionViewHeight = collectionView.bounds.height - collectionView.contentInset.totalHeight
let yPosition = (collectionViewHeight - itemSize.height) / 2
var xPosition: CGFloat = 0
// Create attributes for each item
for item in 0..<itemCount {
let indexPath = IndexPath(item: item, section: 0)
let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
attributes.frame = CGRect(
x: xPosition,
y: yPosition,
width: itemSize.width,
height: itemSize.height,
)
cachedAttributes.append(attributes)
xPosition += itemSize.width + spacing
}
// Remove trailing spacing and add trailing inset
contentWidth = xPosition - spacing
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
cachedAttributes.filter { $0.frame.intersects(rect) }
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
cachedAttributes[safe: indexPath.row]
}
override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
guard let collectionView else { return false }
return newBounds.height != collectionView.bounds.height
}
}