mirror of
https://github.com/Novaloop-AG/element-x-ios.git
synced 2026-11-02 21:33:26 +00:00
Use a view controller for the timeline. (#359)
This exposes lifecycle methods and tidies up the Coordinator.
This commit is contained in:
Doug
GitHub
@@ -63,12 +63,6 @@ struct RoomScreenViewState: BindableState {
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}
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let scrollToBottomPublisher = PassthroughSubject<Void, Never>()
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/// Returns the opacity that the supplied timeline item's cell should be.
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func opacity(for item: RoomTimelineViewProvider) -> CGFloat {
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guard case let .reply(selectedItemID, _) = composerMode else { return 1.0 }
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return selectedItemID == item.id ? 1.0 : 0.5
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}
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}
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struct RoomScreenViewStateBindings {
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@@ -32,7 +32,7 @@ struct RoomScreen: View {
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}
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var timeline: some View {
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TimelineTableView()
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TimelineView()
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.id(context.viewState.roomId)
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.environmentObject(context)
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.timelineStyle(settings.timelineStyle)
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@@ -1,477 +0,0 @@
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//
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// Copyright 2022 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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import Combine
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import SwiftUI
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/// A table view cell that displays a timeline item in a room. The cell is intended
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/// to be configured to display a SwiftUI view and not use any UIKit.
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class TimelineItemCell: UITableViewCell {
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static let reuseIdentifier = "TimelineItemCell"
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var item: RoomTimelineViewProvider?
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override func prepareForReuse() {
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item = nil
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}
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}
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/// A table view wrapper that displays the timeline of a room.
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struct TimelineTableView: UIViewRepresentable {
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@EnvironmentObject private var viewModelContext: RoomScreenViewModel.Context
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@Environment(\.timelineStyle) private var timelineStyle
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func makeUIView(context: Context) -> UITableView {
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let tableView = UITableView(frame: .zero, style: .plain)
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tableView.register(TimelineItemCell.self, forCellReuseIdentifier: TimelineItemCell.reuseIdentifier)
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tableView.separatorStyle = .none
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tableView.allowsSelection = false
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tableView.keyboardDismissMode = .onDrag
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context.coordinator.tableView = tableView
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viewModelContext.send(viewAction: .paginateBackwards)
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return tableView
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}
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func updateUIView(_ uiView: UITableView, context: Context) {
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context.coordinator.update()
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if context.coordinator.timelineStyle != timelineStyle {
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context.coordinator.timelineStyle = timelineStyle
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}
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}
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func makeCoordinator() -> Coordinator {
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Coordinator(viewModelContext: viewModelContext)
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}
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// MARK: - Coordinator
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@MainActor
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class Coordinator: NSObject {
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let viewModelContext: RoomScreenViewModel.Context
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var tableView: UITableView? {
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didSet {
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registerFrameObserver()
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configureDataSource()
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}
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}
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var timelineStyle: TimelineStyle = .bubbles
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var timelineItems: [RoomTimelineViewProvider] = [] {
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didSet {
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guard !scrollAdapter.isScrolling.value else {
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// Delay updating until scrolling has stopped as programatic
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// changes to the scroll position kills any inertia.
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hasPendingUpdates = true
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return
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}
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applySnapshot()
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}
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}
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/// The mode of the message composer. This is used to render selected
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/// items in the timeline when replying, editing etc.
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var composerMode: RoomScreenComposerMode = .default {
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didSet {
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// Reload the visible items in order to update their opacity.
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// Applying a snapshot won't work in this instance as the items don't change.
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reloadVisibleItems()
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}
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}
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/// Whether or not the timeline is waiting for more messages to be added to the top.
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var isBackPaginating = false {
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didSet {
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// Paginate again if the threshold hasn't been satisfied.
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paginateBackwardsPublisher.send(())
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}
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}
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var displayReactionsMenuForItemId = "" {
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didSet {
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tableView?.reloadData()
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}
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}
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/// The table's diffable data source.
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private var dataSource: UITableViewDiffableDataSource<TimelineSection, RoomTimelineViewProvider>?
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private var cancellables: Set<AnyCancellable> = []
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/// The scroll view adapter used to detect whether scrolling is in progress.
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private let scrollAdapter = ScrollViewAdapter()
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/// A publisher used to throttle back pagination requests.
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///
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/// Our view actions get wrapped in a `Task` so it is possible that a second call in
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/// quick succession can execute before ``isBackPaginating`` becomes `true`.
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private let paginateBackwardsPublisher = PassthroughSubject<Void, Never>()
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/// Whether or not the ``timelineItems`` value should be applied when scrolling stops.
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private var hasPendingUpdates = false
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/// The observation token used to handle frame changes.
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private var frameObserverToken: NSKeyValueObservation?
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/// Yucky hack to fix some layouts where the scroll view doesn't make it to the bottom on keyboard appearance.
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var keyboardWillShowLayout: LayoutDescriptor?
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init(viewModelContext: RoomScreenViewModel.Context) {
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self.viewModelContext = viewModelContext
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super.init()
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viewModelContext.viewState.scrollToBottomPublisher
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.sink { [weak self] _ in
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self?.scrollToBottom(animated: true)
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}
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.store(in: &cancellables)
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scrollAdapter.isScrolling
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.sink { [weak self] isScrolling in
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guard !isScrolling, let self, self.hasPendingUpdates else { return }
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// When scrolling has stopped, apply any pending updates.
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self.applySnapshot()
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self.hasPendingUpdates = false
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self.paginateBackwardsPublisher.send(())
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}
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.store(in: &cancellables)
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paginateBackwardsPublisher
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.collect(.byTime(DispatchQueue.main, 0.1))
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.sink { [weak self] _ in
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self?.paginateBackwardsIfNeeded()
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}
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.store(in: &cancellables)
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NotificationCenter.default.publisher(for: UIResponder.keyboardWillShowNotification)
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.sink { [weak self] _ in
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guard let self else { return }
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self.keyboardWillShowLayout = self.layout()
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}
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.store(in: &cancellables)
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NotificationCenter.default.publisher(for: UIResponder.keyboardDidShowNotification)
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.sink { [weak self] _ in
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guard let self, let layout = self.keyboardWillShowLayout, layout.isBottomVisible else { return }
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self.scrollToBottom(animated: false) // Force the bottom to be visible as some timelines misbehave.
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}
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.store(in: &cancellables)
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}
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/// Configures a diffable data source for the timeline's table view.
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private func configureDataSource() {
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guard let tableView else { return }
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dataSource = .init(tableView: tableView) { [weak self] tableView, indexPath, timelineItem in
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let cell = tableView.dequeueReusableCell(withIdentifier: TimelineItemCell.reuseIdentifier, for: indexPath)
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guard let self, let cell = cell as? TimelineItemCell else { return cell }
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// A local reference to avoid capturing self in the cell configuration.
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let viewModelContext = self.viewModelContext
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cell.item = timelineItem
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cell.contentConfiguration = UIHostingConfiguration {
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VStack {
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if viewModelContext.viewState.displayReactionsMenuForItemId == timelineItem.id {
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TimelineItemReactionsMenuView(onEmojiSelected: { emoji in
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viewModelContext.send(viewAction: .emojiTapped(emoji: emoji, itemId: timelineItem.id))
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}, onDisplayEmojiPicker: {
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viewModelContext.send(viewAction: .displayEmojiPicker(itemId: timelineItem.id))
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})
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}
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timelineItem
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.frame(maxWidth: .infinity, alignment: .leading)
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.opacity(viewModelContext.viewState.opacity(for: timelineItem))
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.contextMenu {
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viewModelContext.viewState.contextMenuBuilder?(timelineItem.id)
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}
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.onAppear {
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viewModelContext.send(viewAction: .itemAppeared(id: timelineItem.id))
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}
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.onDisappear {
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viewModelContext.send(viewAction: .itemDisappeared(id: timelineItem.id))
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}
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.environment(\.openURL, OpenURLAction { url in
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viewModelContext.send(viewAction: .linkClicked(url: url))
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return .systemAction
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})
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.onTapGesture(count: 2) {
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viewModelContext.send(viewAction: .displayReactionsMenuForItemId(itemId: timelineItem.id))
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}
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.onTapGesture {
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viewModelContext.send(viewAction: .itemTapped(id: timelineItem.id))
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}
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}
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}
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.margins(.all, self.timelineStyle.rowInsets)
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.minSize(height: 1)
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return cell
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}
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tableView.delegate = self
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}
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/// Adds an observer on the frame of the table view in order to keep the
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/// last item visible when the keyboard is shown or the window resizes.
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private func registerFrameObserver() {
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// Remove the existing observer if necessary
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frameObserverToken?.invalidate()
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frameObserverToken = tableView?.observe(\.frame, options: .new) { [weak self] _, _ in
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self?.handleFrameChange()
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}
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}
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/// Updates the table's layout if necessary after the frame changed.
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private nonisolated func handleFrameChange() {
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Task { @MainActor in
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guard self.composerMode == .default else { return }
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// The table view is yet to update its layout so layout() returns a
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// description of the timeline before the frame change occurs.
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let previousLayout = self.layout()
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if previousLayout.isBottomVisible {
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self.scrollToBottom(animated: false)
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}
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}
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}
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/// Updates the table view's internal state from the view model's context.
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func update() {
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if timelineItems != viewModelContext.viewState.items {
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timelineItems = viewModelContext.viewState.items
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}
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if isBackPaginating != viewModelContext.viewState.isBackPaginating {
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isBackPaginating = viewModelContext.viewState.isBackPaginating
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}
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if composerMode != viewModelContext.viewState.composerMode {
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composerMode = viewModelContext.viewState.composerMode
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}
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if displayReactionsMenuForItemId != viewModelContext.viewState.displayReactionsMenuForItemId {
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displayReactionsMenuForItemId = viewModelContext.viewState.displayReactionsMenuForItemId
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}
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}
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/// Updates the table view with the latest items from the ``timelineItems`` array. After
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/// updating the data, the table will be scrolled to the bottom if it was visible otherwise
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/// the scroll position will be updated to maintain the position of the last visible item.
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private func applySnapshot() {
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guard let dataSource else { return }
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let previousLayout = layout()
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var snapshot = NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>()
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snapshot.appendSections([.main])
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snapshot.appendItems(timelineItems)
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dataSource.apply(snapshot, animatingDifferences: false)
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updateTopPadding()
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guard snapshot.numberOfItems != previousLayout.numberOfItems else { return }
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if previousLayout.isBottomVisible {
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scrollToBottom(animated: false)
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} else if let pinnedItem = previousLayout.pinnedItem {
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restoreScrollPosition(using: pinnedItem, and: snapshot)
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}
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}
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/// Reloads all of the visible timeline items.
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///
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/// This only needs to be called when some state internal to this table view changes that
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/// will affect the appearance of those items. Any updates to the items themselves should
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/// use ``applySnapshot()`` which handles everything in the diffable data source.
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private func reloadVisibleItems() {
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guard let tableView, let visibleIndexPaths = tableView.indexPathsForVisibleRows, let dataSource else { return }
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var snapshot = dataSource.snapshot()
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snapshot.reloadItems(visibleIndexPaths.compactMap { dataSource.itemIdentifier(for: $0) })
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dataSource.apply(snapshot)
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}
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/// Returns a description of the current layout in order to update the
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/// scroll position after adding/updating items to the timeline.
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private func layout() -> LayoutDescriptor {
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guard let tableView, let dataSource else { return LayoutDescriptor() }
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let snapshot = dataSource.snapshot()
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var layout = LayoutDescriptor(numberOfItems: snapshot.numberOfItems)
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guard !snapshot.itemIdentifiers.isEmpty else {
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layout.isBottomVisible = true
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return layout
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}
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guard let bottomItemIndexPath = tableView.indexPathsForVisibleRows?.last,
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let bottomItem = dataSource.itemIdentifier(for: bottomItemIndexPath)
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else { return layout }
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let bottomCellFrame = tableView.cellFrame(for: bottomItem)
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layout.pinnedItem = PinnedItem(id: bottomItem.id, position: .bottom, frame: bottomCellFrame)
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layout.isBottomVisible = bottomItem == snapshot.itemIdentifiers.last
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return layout
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}
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/// Updates the additional padding added to the top of the table (via a header)
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/// in order to fill the timeline from the bottom of the view upwards.
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private func updateTopPadding() {
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guard let tableView else { return }
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let contentHeight = tableView.contentSize.height - (tableView.tableHeaderView?.frame.height ?? 0)
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let height = tableView.visibleSize.height - contentHeight
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if height > 0 {
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let frame = CGRect(origin: .zero, size: CGSize(width: tableView.contentSize.width, height: height))
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tableView.tableHeaderView = UIView(frame: frame) // Updating an existing view's height doesn't move the cells.
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} else {
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tableView.tableHeaderView = nil
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}
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}
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/// Whether or not the bottom of the scroll view is visible (with some small tolerance added).
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private func isAtBottom(of scrollView: UIScrollView) -> Bool {
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scrollView.contentOffset.y < (scrollView.contentSize.height - scrollView.visibleSize.height - 15)
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}
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/// Scrolls to the bottom of the timeline.
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private func scrollToBottom(animated: Bool) {
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guard let lastItem = timelineItems.last,
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let lastIndexPath = dataSource?.indexPath(for: lastItem)
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else { return }
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tableView?.scrollToRow(at: lastIndexPath, at: .bottom, animated: animated)
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}
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/// Restores the position of the timeline using the supplied item and snapshot.
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private func restoreScrollPosition(using pinnedItem: PinnedItem, and snapshot: NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>) {
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guard let tableView,
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let item = snapshot.itemIdentifiers.first(where: { $0.id == pinnedItem.id }),
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let indexPath = dataSource?.indexPath(for: item)
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else { return }
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// Scroll the item into view.
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tableView.scrollToRow(at: indexPath, at: pinnedItem.position, animated: false)
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guard let oldFrame = pinnedItem.frame, let newFrame = tableView.cellFrame(for: item) else { return }
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// Remove any unwanted offset that was added by scrollToRow.
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let deltaY = newFrame.maxY - oldFrame.maxY
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if deltaY != 0 {
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tableView.contentOffset.y += deltaY
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}
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}
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/// Checks whether or a backwards pagination is needed and requests one if so.
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///
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/// Prefer not to call this directly, instead using ``paginateBackwardsPublisher`` to throttle requests.
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private func paginateBackwardsIfNeeded() {
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guard let tableView,
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!isBackPaginating,
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!hasPendingUpdates,
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tableView.contentOffset.y < tableView.visibleSize.height * 2.0
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else { return }
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viewModelContext.send(viewAction: .paginateBackwards)
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}
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}
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}
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// MARK: - UITableViewDelegate
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extension TimelineTableView.Coordinator: UITableViewDelegate {
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func scrollViewDidScroll(_ scrollView: UIScrollView) {
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let isAtBottom = isAtBottom(of: scrollView)
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if !viewModelContext.scrollToBottomButtonVisible, isAtBottom {
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DispatchQueue.main.async { self.viewModelContext.scrollToBottomButtonVisible = true }
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} else if viewModelContext.scrollToBottomButtonVisible, !isAtBottom {
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DispatchQueue.main.async { self.viewModelContext.scrollToBottomButtonVisible = false }
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}
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paginateBackwardsPublisher.send(())
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}
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// MARK: - ScrollViewAdapter
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// Required delegate methods are forwarded to the adapter so others can be implemented.
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func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
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scrollAdapter.scrollViewWillBeginDragging(scrollView)
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}
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func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
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scrollAdapter.scrollViewDidEndDragging(scrollView, willDecelerate: decelerate)
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}
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func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
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scrollAdapter.scrollViewDidEndScrollingAnimation(scrollView)
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}
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func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
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scrollAdapter.scrollViewDidEndDecelerating(scrollView)
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}
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func scrollViewDidScrollToTop(_ scrollView: UIScrollView) {
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scrollAdapter.scrollViewDidScrollToTop(scrollView)
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}
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}
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// MARK: - Layout Types
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extension TimelineTableView.Coordinator {
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/// The sections of the table view used in the diffable data source.
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enum TimelineSection { case main }
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/// A description of the timeline's layout.
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struct LayoutDescriptor {
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var numberOfItems = 0
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var pinnedItem: PinnedItem?
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var isBottomVisible = false
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}
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/// An item that should have its position pinned after updates.
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struct PinnedItem {
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let id: String
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let position: UITableView.ScrollPosition
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let frame: CGRect?
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}
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}
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// MARK: - Cell Layout
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private extension UITableView {
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/// Returns the frame of the cell for a particular timeline item.
|
||||
func cellFrame(for item: RoomTimelineViewProvider) -> CGRect? {
|
||||
guard let timelineCell = visibleCells.last(where: { ($0 as? TimelineItemCell)?.item == item }) else {
|
||||
return nil
|
||||
}
|
||||
|
||||
return convert(timelineCell.frame, to: superview)
|
||||
}
|
||||
}
|
||||
|
||||
// MARK: - Previews
|
||||
|
||||
struct TimelineTableView_Previews: PreviewProvider {
|
||||
static var previews: some View {
|
||||
let viewModel = RoomScreenViewModel(timelineController: MockRoomTimelineController(),
|
||||
timelineViewFactory: RoomTimelineViewFactory(),
|
||||
mediaProvider: MockMediaProvider(),
|
||||
roomName: "Preview room")
|
||||
|
||||
NavigationView {
|
||||
RoomScreen(context: viewModel.context)
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,440 @@
|
||||
//
|
||||
// Copyright 2022 New Vector Ltd
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
//
|
||||
|
||||
import Combine
|
||||
import SwiftUI
|
||||
|
||||
/// A table view cell that displays a timeline item in a room. The cell is intended
|
||||
/// to be configured to display a SwiftUI view and not use any UIKit.
|
||||
class TimelineItemCell: UITableViewCell {
|
||||
static let reuseIdentifier = "TimelineItemCell"
|
||||
|
||||
var item: RoomTimelineViewProvider?
|
||||
|
||||
override func prepareForReuse() {
|
||||
item = nil
|
||||
}
|
||||
}
|
||||
|
||||
/// A table view controller that displays the timeline of a room.
|
||||
///
|
||||
/// This class subclasses `UIViewController` as `UITableViewController` adds some
|
||||
/// extra keyboard handling magic that wasn't playing well with SwiftUI (as of iOS 16.1).
|
||||
class TimelineTableViewController: UIViewController {
|
||||
let coordinator: TimelineView.Coordinator
|
||||
let tableView = UITableView(frame: .zero, style: .plain)
|
||||
|
||||
var timelineStyle: TimelineStyle
|
||||
var timelineItems: [RoomTimelineViewProvider] = [] {
|
||||
didSet {
|
||||
guard !scrollAdapter.isScrolling.value else {
|
||||
// Delay updating until scrolling has stopped as programatic
|
||||
// changes to the scroll position kills any inertia.
|
||||
hasPendingUpdates = true
|
||||
return
|
||||
}
|
||||
|
||||
applySnapshot()
|
||||
}
|
||||
}
|
||||
|
||||
/// The mode of the message composer. This is used to render selected
|
||||
/// items in the timeline when replying, editing etc.
|
||||
var composerMode: RoomScreenComposerMode = .default {
|
||||
didSet {
|
||||
// Reload the visible items in order to update their opacity.
|
||||
// Applying a snapshot won't work in this instance as the items don't change.
|
||||
reloadVisibleItems()
|
||||
}
|
||||
}
|
||||
|
||||
/// Whether or not the timeline is waiting for more messages to be added to the top.
|
||||
var isBackPaginating = false {
|
||||
didSet {
|
||||
// Paginate again if the threshold hasn't been satisfied.
|
||||
paginateBackwardsPublisher.send(())
|
||||
}
|
||||
}
|
||||
|
||||
var displayReactionsMenuForItemId = "" {
|
||||
didSet {
|
||||
tableView.reloadData()
|
||||
}
|
||||
}
|
||||
|
||||
var contextMenuBuilder: (@MainActor (_ itemId: String) -> TimelineItemContextMenu)?
|
||||
|
||||
@Binding private var scrollToBottomButtonVisible: Bool
|
||||
|
||||
/// The table's diffable data source.
|
||||
private var dataSource: UITableViewDiffableDataSource<TimelineSection, RoomTimelineViewProvider>?
|
||||
private var cancellables: Set<AnyCancellable> = []
|
||||
|
||||
/// The scroll view adapter used to detect whether scrolling is in progress.
|
||||
private let scrollAdapter = ScrollViewAdapter()
|
||||
/// A publisher used to throttle back pagination requests.
|
||||
///
|
||||
/// Our view actions get wrapped in a `Task` so it is possible that a second call in
|
||||
/// quick succession can execute before ``isBackPaginating`` becomes `true`.
|
||||
private let paginateBackwardsPublisher = PassthroughSubject<Void, Never>()
|
||||
/// Whether or not the ``timelineItems`` value should be applied when scrolling stops.
|
||||
private var hasPendingUpdates = false
|
||||
/// Yucky hack to fix some layouts where the scroll view doesn't make it to the bottom on keyboard appearance.
|
||||
private var keyboardWillShowLayout: LayoutDescriptor?
|
||||
/// Whether or not the view has been shown on screen yet.
|
||||
private var hasAppearedOnce = false
|
||||
|
||||
init(coordinator: TimelineView.Coordinator,
|
||||
timelineStyle: TimelineStyle,
|
||||
scrollToBottomButtonVisible: Binding<Bool>,
|
||||
scrollToBottomPublisher: PassthroughSubject<Void, Never>) {
|
||||
self.coordinator = coordinator
|
||||
self.timelineStyle = timelineStyle
|
||||
_scrollToBottomButtonVisible = scrollToBottomButtonVisible
|
||||
|
||||
super.init(nibName: nil, bundle: nil)
|
||||
|
||||
tableView.register(TimelineItemCell.self, forCellReuseIdentifier: TimelineItemCell.reuseIdentifier)
|
||||
tableView.separatorStyle = .none
|
||||
tableView.allowsSelection = false
|
||||
tableView.keyboardDismissMode = .onDrag
|
||||
view.addSubview(tableView)
|
||||
|
||||
scrollToBottomPublisher
|
||||
.sink { [weak self] _ in
|
||||
self?.scrollToBottom(animated: true)
|
||||
}
|
||||
.store(in: &cancellables)
|
||||
|
||||
scrollAdapter.isScrolling
|
||||
.sink { [weak self] isScrolling in
|
||||
guard !isScrolling, let self, self.hasPendingUpdates else { return }
|
||||
// When scrolling has stopped, apply any pending updates.
|
||||
self.applySnapshot()
|
||||
self.hasPendingUpdates = false
|
||||
self.paginateBackwardsPublisher.send(())
|
||||
}
|
||||
.store(in: &cancellables)
|
||||
|
||||
paginateBackwardsPublisher
|
||||
.collect(.byTime(DispatchQueue.main, 0.1))
|
||||
.sink { [weak self] _ in
|
||||
self?.paginateBackwardsIfNeeded()
|
||||
}
|
||||
.store(in: &cancellables)
|
||||
|
||||
NotificationCenter.default.publisher(for: UIResponder.keyboardWillShowNotification)
|
||||
.sink { [weak self] _ in
|
||||
guard let self else { return }
|
||||
self.keyboardWillShowLayout = self.layout()
|
||||
}
|
||||
.store(in: &cancellables)
|
||||
|
||||
NotificationCenter.default.publisher(for: UIResponder.keyboardDidShowNotification)
|
||||
.sink { [weak self] _ in
|
||||
guard let self, let layout = self.keyboardWillShowLayout, layout.isBottomVisible else { return }
|
||||
self.scrollToBottom(animated: false) // Force the bottom to be visible as some timelines misbehave.
|
||||
}
|
||||
.store(in: &cancellables)
|
||||
|
||||
configureDataSource()
|
||||
}
|
||||
|
||||
@available(*, unavailable)
|
||||
required init?(coder: NSCoder) { fatalError("init(coder:) is not available.") }
|
||||
|
||||
override func viewWillAppear(_ animated: Bool) {
|
||||
super.viewWillAppear(animated)
|
||||
|
||||
guard !hasAppearedOnce else { return }
|
||||
scrollToBottom(animated: false)
|
||||
hasAppearedOnce = true
|
||||
}
|
||||
|
||||
override func viewWillLayoutSubviews() {
|
||||
super.viewWillLayoutSubviews()
|
||||
|
||||
guard tableView.frame.size != view.frame.size else { return }
|
||||
tableView.frame = CGRect(origin: .zero, size: view.frame.size)
|
||||
|
||||
// Update the table's layout if necessary after the frame changed.
|
||||
updateTopPadding()
|
||||
|
||||
guard composerMode == .default else { return }
|
||||
|
||||
// The table view is yet to update its content so layout() returns a
|
||||
// description of the timeline before the frame change occurs.
|
||||
let previousLayout = layout()
|
||||
if previousLayout.isBottomVisible {
|
||||
scrollToBottom(animated: false)
|
||||
}
|
||||
}
|
||||
|
||||
/// Configures a diffable data source for the timeline's table view.
|
||||
private func configureDataSource() {
|
||||
dataSource = .init(tableView: tableView) { [weak self] tableView, indexPath, timelineItem in
|
||||
let cell = tableView.dequeueReusableCell(withIdentifier: TimelineItemCell.reuseIdentifier, for: indexPath)
|
||||
guard let self, let cell = cell as? TimelineItemCell else { return cell }
|
||||
|
||||
// A local reference to avoid capturing self in the cell configuration.
|
||||
let coordinator = self.coordinator
|
||||
let opacity = self.opacity(for: timelineItem)
|
||||
let displayReactionsMenuForItemId = self.displayReactionsMenuForItemId
|
||||
let contextMenuBuilder = self.contextMenuBuilder
|
||||
|
||||
cell.item = timelineItem
|
||||
cell.contentConfiguration = UIHostingConfiguration {
|
||||
VStack {
|
||||
if displayReactionsMenuForItemId == timelineItem.id {
|
||||
TimelineItemReactionsMenuView { emoji in
|
||||
coordinator.send(viewAction: .emojiTapped(emoji: emoji, itemId: timelineItem.id))
|
||||
} onDisplayEmojiPicker: {
|
||||
coordinator.send(viewAction: .displayEmojiPicker(itemId: timelineItem.id))
|
||||
}
|
||||
}
|
||||
|
||||
timelineItem
|
||||
.frame(maxWidth: .infinity, alignment: .leading)
|
||||
.opacity(opacity)
|
||||
.contextMenu {
|
||||
contextMenuBuilder?(timelineItem.id)
|
||||
}
|
||||
.onAppear {
|
||||
coordinator.send(viewAction: .itemAppeared(id: timelineItem.id))
|
||||
}
|
||||
.onDisappear {
|
||||
coordinator.send(viewAction: .itemDisappeared(id: timelineItem.id))
|
||||
}
|
||||
.environment(\.openURL, OpenURLAction { url in
|
||||
coordinator.send(viewAction: .linkClicked(url: url))
|
||||
return .systemAction
|
||||
})
|
||||
.onTapGesture(count: 2) {
|
||||
coordinator.send(viewAction: .displayReactionsMenuForItemId(itemId: timelineItem.id))
|
||||
}
|
||||
.onTapGesture {
|
||||
coordinator.send(viewAction: .itemTapped(id: timelineItem.id))
|
||||
}
|
||||
}
|
||||
}
|
||||
.margins(.all, self.timelineStyle.rowInsets)
|
||||
.minSize(height: 1)
|
||||
|
||||
return cell
|
||||
}
|
||||
|
||||
tableView.delegate = self
|
||||
}
|
||||
|
||||
/// Updates the table view with the latest items from the ``timelineItems`` array. After
|
||||
/// updating the data, the table will be scrolled to the bottom if it was visible otherwise
|
||||
/// the scroll position will be updated to maintain the position of the last visible item.
|
||||
private func applySnapshot() {
|
||||
guard let dataSource else { return }
|
||||
|
||||
let previousLayout = layout()
|
||||
|
||||
var snapshot = NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>()
|
||||
snapshot.appendSections([.main])
|
||||
snapshot.appendItems(timelineItems)
|
||||
dataSource.apply(snapshot, animatingDifferences: false)
|
||||
|
||||
updateTopPadding()
|
||||
|
||||
guard snapshot.numberOfItems != previousLayout.numberOfItems else { return }
|
||||
|
||||
if previousLayout.isBottomVisible {
|
||||
scrollToBottom(animated: false)
|
||||
} else if let pinnedItem = previousLayout.pinnedItem {
|
||||
restoreScrollPosition(using: pinnedItem, and: snapshot)
|
||||
}
|
||||
}
|
||||
|
||||
/// Reloads all of the visible timeline items.
|
||||
///
|
||||
/// This only needs to be called when some state internal to this table view changes that
|
||||
/// will affect the appearance of those items. Any updates to the items themselves should
|
||||
/// use ``applySnapshot()`` which handles everything in the diffable data source.
|
||||
private func reloadVisibleItems() {
|
||||
guard let visibleIndexPaths = tableView.indexPathsForVisibleRows, let dataSource else { return }
|
||||
var snapshot = dataSource.snapshot()
|
||||
snapshot.reloadItems(visibleIndexPaths.compactMap { dataSource.itemIdentifier(for: $0) })
|
||||
dataSource.apply(snapshot)
|
||||
}
|
||||
|
||||
/// Returns a description of the current layout in order to update the
|
||||
/// scroll position after adding/updating items to the timeline.
|
||||
private func layout() -> LayoutDescriptor {
|
||||
guard let dataSource else { return LayoutDescriptor() }
|
||||
|
||||
let snapshot = dataSource.snapshot()
|
||||
var layout = LayoutDescriptor(numberOfItems: snapshot.numberOfItems)
|
||||
|
||||
guard !snapshot.itemIdentifiers.isEmpty else {
|
||||
layout.isBottomVisible = true
|
||||
return layout
|
||||
}
|
||||
|
||||
guard let bottomItemIndexPath = tableView.indexPathsForVisibleRows?.last,
|
||||
let bottomItem = dataSource.itemIdentifier(for: bottomItemIndexPath)
|
||||
else { return layout }
|
||||
|
||||
let bottomCellFrame = tableView.cellFrame(for: bottomItem)
|
||||
layout.pinnedItem = PinnedItem(id: bottomItem.id, position: .bottom, frame: bottomCellFrame)
|
||||
layout.isBottomVisible = bottomItem == snapshot.itemIdentifiers.last
|
||||
|
||||
return layout
|
||||
}
|
||||
|
||||
/// Updates the additional padding added to the top of the table (via a header)
|
||||
/// in order to fill the timeline from the bottom of the view upwards.
|
||||
private func updateTopPadding() {
|
||||
let contentHeight = tableView.contentSize.height - (tableView.tableHeaderView?.frame.height ?? 0)
|
||||
let height = tableView.visibleSize.height - contentHeight
|
||||
|
||||
if height > 0 {
|
||||
let frame = CGRect(origin: .zero, size: CGSize(width: tableView.contentSize.width, height: height))
|
||||
tableView.tableHeaderView = UIView(frame: frame) // Updating an existing view's height doesn't move the cells.
|
||||
} else {
|
||||
tableView.tableHeaderView = nil
|
||||
}
|
||||
}
|
||||
|
||||
/// Whether or not the bottom of the scroll view is visible (with some small tolerance added).
|
||||
private func isAtBottom() -> Bool {
|
||||
tableView.contentOffset.y < (tableView.contentSize.height - tableView.visibleSize.height - 15)
|
||||
}
|
||||
|
||||
/// Scrolls to the bottom of the timeline.
|
||||
private func scrollToBottom(animated: Bool) {
|
||||
guard let lastItem = timelineItems.last,
|
||||
let lastIndexPath = dataSource?.indexPath(for: lastItem)
|
||||
else { return }
|
||||
|
||||
tableView.scrollToRow(at: lastIndexPath, at: .bottom, animated: animated)
|
||||
}
|
||||
|
||||
/// Restores the position of the timeline using the supplied item and snapshot.
|
||||
private func restoreScrollPosition(using pinnedItem: PinnedItem, and snapshot: NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>) {
|
||||
guard let item = snapshot.itemIdentifiers.first(where: { $0.id == pinnedItem.id }),
|
||||
let indexPath = dataSource?.indexPath(for: item)
|
||||
else { return }
|
||||
|
||||
// Scroll the item into view.
|
||||
tableView.scrollToRow(at: indexPath, at: pinnedItem.position, animated: false)
|
||||
|
||||
guard let oldFrame = pinnedItem.frame, let newFrame = tableView.cellFrame(for: item) else { return }
|
||||
|
||||
// Remove any unwanted offset that was added by scrollToRow.
|
||||
let deltaY = newFrame.maxY - oldFrame.maxY
|
||||
if deltaY != 0 {
|
||||
tableView.contentOffset.y += deltaY
|
||||
}
|
||||
}
|
||||
|
||||
/// Checks whether or a backwards pagination is needed and requests one if so.
|
||||
///
|
||||
/// Prefer not to call this directly, instead using ``paginateBackwardsPublisher`` to throttle requests.
|
||||
private func paginateBackwardsIfNeeded() {
|
||||
guard !isBackPaginating,
|
||||
!hasPendingUpdates,
|
||||
tableView.contentOffset.y < tableView.visibleSize.height * 2.0
|
||||
else { return }
|
||||
|
||||
coordinator.send(viewAction: .paginateBackwards)
|
||||
}
|
||||
|
||||
/// Returns the opacity that the supplied timeline item's cell should be.
|
||||
private func opacity(for item: RoomTimelineViewProvider) -> CGFloat {
|
||||
guard case let .reply(selectedItemID, _) = composerMode else { return 1.0 }
|
||||
return selectedItemID == item.id ? 1.0 : 0.5
|
||||
}
|
||||
}
|
||||
|
||||
// MARK: - UITableViewDelegate
|
||||
|
||||
extension TimelineTableViewController: UITableViewDelegate {
|
||||
func scrollViewDidScroll(_ scrollView: UIScrollView) {
|
||||
let isAtBottom = isAtBottom()
|
||||
|
||||
// Dispatches fix runtime warnings about making changes during a view update.
|
||||
if !scrollToBottomButtonVisible, isAtBottom {
|
||||
DispatchQueue.main.async { self.scrollToBottomButtonVisible = true }
|
||||
} else if scrollToBottomButtonVisible, !isAtBottom {
|
||||
DispatchQueue.main.async { self.scrollToBottomButtonVisible = false }
|
||||
}
|
||||
|
||||
paginateBackwardsPublisher.send(())
|
||||
}
|
||||
|
||||
// MARK: ScrollViewAdapter Methods
|
||||
|
||||
// Required delegate methods are forwarded to the adapter so others can be implemented.
|
||||
|
||||
func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
|
||||
scrollAdapter.scrollViewWillBeginDragging(scrollView)
|
||||
}
|
||||
|
||||
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
|
||||
scrollAdapter.scrollViewDidEndDragging(scrollView, willDecelerate: decelerate)
|
||||
}
|
||||
|
||||
func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
|
||||
scrollAdapter.scrollViewDidEndScrollingAnimation(scrollView)
|
||||
}
|
||||
|
||||
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
|
||||
scrollAdapter.scrollViewDidEndDecelerating(scrollView)
|
||||
}
|
||||
|
||||
func scrollViewDidScrollToTop(_ scrollView: UIScrollView) {
|
||||
scrollAdapter.scrollViewDidScrollToTop(scrollView)
|
||||
}
|
||||
}
|
||||
|
||||
// MARK: - Layout Types
|
||||
|
||||
extension TimelineTableViewController {
|
||||
/// The sections of the table view used in the diffable data source.
|
||||
enum TimelineSection { case main }
|
||||
|
||||
/// A description of the timeline's layout.
|
||||
struct LayoutDescriptor {
|
||||
var numberOfItems = 0
|
||||
var pinnedItem: PinnedItem?
|
||||
var isBottomVisible = false
|
||||
}
|
||||
|
||||
/// An item that should have its position pinned after updates.
|
||||
struct PinnedItem {
|
||||
let id: String
|
||||
let position: UITableView.ScrollPosition
|
||||
let frame: CGRect?
|
||||
}
|
||||
}
|
||||
|
||||
// MARK: - Cell Layout
|
||||
|
||||
private extension UITableView {
|
||||
/// Returns the frame of the cell for a particular timeline item.
|
||||
func cellFrame(for item: RoomTimelineViewProvider) -> CGRect? {
|
||||
guard let timelineCell = visibleCells.last(where: { ($0 as? TimelineItemCell)?.item == item }) else {
|
||||
return nil
|
||||
}
|
||||
|
||||
return convert(timelineCell.frame, to: superview)
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,92 @@
|
||||
//
|
||||
// Copyright 2022 New Vector Ltd
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
//
|
||||
|
||||
import SwiftUI
|
||||
|
||||
/// A table view wrapper that displays the timeline of a room.
|
||||
struct TimelineView: UIViewControllerRepresentable {
|
||||
@EnvironmentObject private var viewModelContext: RoomScreenViewModel.Context
|
||||
@Environment(\.timelineStyle) private var timelineStyle
|
||||
|
||||
func makeUIViewController(context: Context) -> TimelineTableViewController {
|
||||
let tableViewController = TimelineTableViewController(coordinator: context.coordinator,
|
||||
timelineStyle: timelineStyle,
|
||||
scrollToBottomButtonVisible: $viewModelContext.scrollToBottomButtonVisible,
|
||||
scrollToBottomPublisher: viewModelContext.viewState.scrollToBottomPublisher)
|
||||
viewModelContext.send(viewAction: .paginateBackwards)
|
||||
return tableViewController
|
||||
}
|
||||
|
||||
func updateUIViewController(_ uiViewController: TimelineTableViewController, context: Context) {
|
||||
context.coordinator.update(tableViewController: uiViewController, timelineStyle: timelineStyle)
|
||||
}
|
||||
|
||||
func makeCoordinator() -> Coordinator {
|
||||
Coordinator(viewModelContext: viewModelContext)
|
||||
}
|
||||
|
||||
// MARK: - Coordinator
|
||||
|
||||
@MainActor
|
||||
class Coordinator {
|
||||
let context: RoomScreenViewModel.Context
|
||||
|
||||
init(viewModelContext: RoomScreenViewModel.Context) {
|
||||
context = viewModelContext
|
||||
}
|
||||
|
||||
/// Updates the specified table view's properties from the current view state.
|
||||
func update(tableViewController: TimelineTableViewController, timelineStyle: TimelineStyle) {
|
||||
if tableViewController.timelineStyle != timelineStyle {
|
||||
tableViewController.timelineStyle = timelineStyle
|
||||
}
|
||||
if tableViewController.timelineItems != context.viewState.items {
|
||||
tableViewController.timelineItems = context.viewState.items
|
||||
}
|
||||
if tableViewController.isBackPaginating != context.viewState.isBackPaginating {
|
||||
tableViewController.isBackPaginating = context.viewState.isBackPaginating
|
||||
}
|
||||
if tableViewController.composerMode != context.viewState.composerMode {
|
||||
tableViewController.composerMode = context.viewState.composerMode
|
||||
}
|
||||
if tableViewController.displayReactionsMenuForItemId != context.viewState.displayReactionsMenuForItemId {
|
||||
tableViewController.displayReactionsMenuForItemId = context.viewState.displayReactionsMenuForItemId
|
||||
}
|
||||
|
||||
// Doesn't have an equatable conformance :(
|
||||
tableViewController.contextMenuBuilder = context.viewState.contextMenuBuilder
|
||||
}
|
||||
|
||||
func send(viewAction: RoomScreenViewAction) {
|
||||
context.send(viewAction: viewAction)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// MARK: - Previews
|
||||
|
||||
struct TimelineTableView_Previews: PreviewProvider {
|
||||
static var previews: some View {
|
||||
let viewModel = RoomScreenViewModel(timelineController: MockRoomTimelineController(),
|
||||
timelineViewFactory: RoomTimelineViewFactory(),
|
||||
mediaProvider: MockMediaProvider(),
|
||||
roomName: "Preview room")
|
||||
|
||||
NavigationView {
|
||||
RoomScreen(context: viewModel.context)
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user