Use a VStack on the timeline (#332)

* Use a VStack for the timeline.

Replace edge publishers with a binding.

* Allow both top and bottom edges to be detected.

* Fix scrolling with frame changes.
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Doug 2022-11-22 13:28:35 +00:00 committed by GitHub
parent 6c2ea61585
commit 5c4ca74426
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8 changed files with 160 additions and 193 deletions

View File

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@ -1629,6 +1629,7 @@
804F9B0FABE093C7284CD09B /* TimelineItemList.swift */,
0BC588051E6572A1AF51D738 /* TimelineSenderAvatarView.swift */,
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C2DE30233B57761F8AFEB415 /* TimelineScrollView.swift */,
A312471EA62EFB0FD94E60DC /* Style */,
CCD48459CA34A1928EC7A26A /* Supplementary */,
B7D3886505ECC85A06DA8258 /* Timeline */,
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@ -2889,7 +2889,7 @@
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View File

@ -1,82 +0,0 @@
//
// 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 SwiftUI scroll view that lays out its content starting at the bottom or trailing
/// https://www.thirdrocktechkno.com/blog/implementing-reversed-scrolling-behaviour-in-swiftui/
struct ReversedScrollView<Content: View>: View {
private let axis: Axis.Set
private let leadingSpace: CGFloat
private let content: Content
init(_ axis: Axis.Set = .horizontal, leadingSpace: CGFloat = 0, @ViewBuilder builder: () -> Content) {
self.axis = axis
self.leadingSpace = leadingSpace
content = builder()
}
var body: some View {
GeometryReader { proxy in
ScrollView(axis, showsIndicators: false) {
Stack(axis) {
Spacer(minLength: leadingSpace)
content
}
.frame(
minWidth: minWidth(in: proxy, for: axis),
minHeight: minHeight(in: proxy, for: axis)
)
}
}
}
private func minWidth(in proxy: GeometryProxy, for axis: Axis.Set) -> CGFloat? {
axis.contains(.horizontal) ? proxy.size.width : nil
}
private func minHeight(in proxy: GeometryProxy, for axis: Axis.Set) -> CGFloat? {
axis.contains(.vertical) ? proxy.size.height : nil
}
}
private struct Stack<Content: View>: View {
var axis: Axis.Set
var content: Content
init(_ axis: Axis.Set = .vertical, @ViewBuilder builder: () -> Content) {
self.axis = axis
content = builder()
}
var body: some View {
switch axis {
case .horizontal:
HStack {
content
}
case .vertical:
VStack {
content
}
default:
VStack {
content
}
}
}
}

View File

@ -38,7 +38,7 @@ struct ImageRoomTimelineView: View {
.foregroundColor(.element.systemGray6)
.opacity(0.3)
ProgressView("Loading")
ProgressView(ElementL10n.loading)
.frame(maxWidth: .infinity)
}
.aspectRatio(timelineItem.aspectRatio, contentMode: .fit)
@ -46,7 +46,6 @@ struct ImageRoomTimelineView: View {
}
.id(timelineItem.id)
.animation(.elementDefault, value: timelineItem.image)
.frame(maxHeight: 1000.0)
}
}

View File

@ -34,7 +34,7 @@ struct VideoRoomTimelineView: View {
.foregroundColor(.element.systemGray6)
.opacity(0.3)
ProgressView("Loading")
ProgressView(ElementL10n.loading)
.frame(maxWidth: .infinity)
}
.aspectRatio(timelineItem.aspectRatio, contentMode: .fit)
@ -42,7 +42,6 @@ struct VideoRoomTimelineView: View {
}
.id(timelineItem.id)
.animation(.elementDefault, value: timelineItem.image)
.frame(maxHeight: 1000.0)
}
@ViewBuilder

View File

@ -23,76 +23,74 @@ struct TimelineItemList: View {
@State private var timelineItems: [RoomTimelineViewProvider] = []
@State private var viewFrame: CGRect = .zero
@State private var pinnedItem: PinnedItem?
@State private var visibleItemIdentifiers: Set<String> = []
@State private var topVisiblePublisher = CurrentValueSubject<Bool, Never>(false)
@Binding var visibleEdges: [VerticalEdge]
/// The last known value of the visible edges. This is stored because `visibleEdges`
/// updates at the same time as the `viewFrame` but we need to know the previous
/// value when the keyboard appears to determine whether to scroll to the bottom.
@State private var cachedVisibleEdges: [VerticalEdge] = []
@EnvironmentObject var context: RoomScreenViewModel.Context
let bottomVisiblePublisher: CurrentValueSubject<Bool, Never>
let scrollToBottomPublisher: PassthroughSubject<Void, Never>
var body: some View {
ScrollViewReader { proxy in
ReversedScrollView(.vertical) {
ScrollViewReader { scrollView in
TimelineScrollView(visibleEdges: $visibleEdges) {
// The scroll view already contains a VStack so simply provide the content to fill it.
ProgressView()
.frame(maxWidth: .infinity)
.opacity(context.viewState.isBackPaginating ? 1.0 : 0.0)
.animation(.elementDefault, value: context.viewState.isBackPaginating)
LazyVStack(alignment: .leading, spacing: 0.0) {
ForEach(isRunningPreviews ? context.viewState.items : timelineItems) { item in
item
.contextMenu {
context.viewState.contextMenuBuilder?(item.id)
.id(item.id)
}
.opacity(opacityForItem(item))
.padding(settings.timelineStyle.rowInsets)
.onAppear {
context.send(viewAction: .itemAppeared(id: item.id))
visibleItemIdentifiers.insert(item.id)
if timelineItems.first == item {
topVisiblePublisher.send(true)
}
if timelineItems.last == item {
bottomVisiblePublisher.send(true)
}
}
.onDisappear {
context.send(viewAction: .itemDisappeared(id: item.id))
visibleItemIdentifiers.remove(item.id)
if timelineItems.first == item {
topVisiblePublisher.send(false)
}
if timelineItems.last == item {
bottomVisiblePublisher.send(false)
}
}
.environment(\.openURL, OpenURLAction { url in
context.send(viewAction: .linkClicked(url: url))
return .systemAction
})
.onTapGesture {
context.send(viewAction: .itemTapped(id: item.id))
}
}
ForEach(isRunningPreviews ? context.viewState.items : timelineItems) { item in
item
.contextMenu {
context.viewState.contextMenuBuilder?(item.id)
.id(item.id)
}
.opacity(opacityForItem(item))
.padding(settings.timelineStyle.rowInsets)
.onAppear {
context.send(viewAction: .itemAppeared(id: item.id))
}
.onDisappear {
context.send(viewAction: .itemDisappeared(id: item.id))
}
.environment(\.openURL, OpenURLAction { url in
context.send(viewAction: .linkClicked(url: url))
return .systemAction
})
.onTapGesture {
context.send(viewAction: .itemTapped(id: item.id))
}
}
}
.onChange(of: visibleEdges) { edges in
cachedVisibleEdges = edges
// Paginate when the top becomes visible
guard edges.contains(.top) else { return }
requestBackPagination()
}
.onChange(of: context.viewState.isBackPaginating) { isBackPaginating in
guard !isBackPaginating else { return }
// Repeat the pagination if the top edge is still visible.
DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
guard visibleEdges.contains(.top) else { return }
requestBackPagination()
}
}
.onChange(of: pinnedItem) { item in
guard let item else {
return
}
guard let item else { return }
if item.animated {
withAnimation(Animation.elementDefault) {
proxy.scrollTo(item.id, anchor: item.anchor)
scrollView.scrollTo(item.id, anchor: item.anchor)
}
} else {
proxy.scrollTo(item.id, anchor: item.anchor)
scrollView.scrollTo(item.id, anchor: item.anchor)
}
pinnedItem = nil
@ -103,20 +101,17 @@ struct TimelineItemList: View {
.timelineStyle(settings.timelineStyle)
.onAppear {
timelineItems = context.viewState.items
requestBackPagination()
}
// Allow SwiftUI to layout the views properly before checking if the top is visible
.onReceive(topVisiblePublisher.collect(.byTime(DispatchQueue.main, 0.5))) { values in
if values.last == true {
requestBackPagination()
}
}
.onReceive(scrollToBottomPublisher) {
scrollToBottom(animated: true)
}
.onChange(of: context.viewState.items.count) { _ in
guard !context.viewState.items.isEmpty,
context.viewState.items.count != timelineItems.count else {
.onChange(of: context.viewState.items) { items in
guard
!context.viewState.items.isEmpty,
context.viewState.items.count != timelineItems.count
else {
// Update the items, but don't worry about scrolling if the count is unchanged.
timelineItems = items
return
}
@ -132,9 +127,7 @@ struct TimelineItemList: View {
}
// Pin to the new bottom if visible
if let currentLastItem = timelineItems.last,
visibleItemIdentifiers.contains(currentLastItem.id),
let newLastItem = context.viewState.items.last {
if visibleEdges.contains(.bottom), let newLastItem = context.viewState.items.last {
let pinnedItem = PinnedItem(id: newLastItem.id, anchor: .bottom, animated: false)
timelineItems = context.viewState.items
self.pinnedItem = pinnedItem
@ -143,8 +136,7 @@ struct TimelineItemList: View {
}
// Pin to the old topmost visible
if let currentFirstItem = timelineItems.first,
visibleItemIdentifiers.contains(currentFirstItem.id) {
if visibleEdges.contains(.top), let currentFirstItem = timelineItems.first {
let pinnedItem = PinnedItem(id: currentFirstItem.id, anchor: .top, animated: false)
timelineItems = context.viewState.items
self.pinnedItem = pinnedItem
@ -155,18 +147,10 @@ struct TimelineItemList: View {
// Otherwise just update the items
timelineItems = context.viewState.items
}
.onChange(of: context.viewState.items, perform: { items in
if timelineItems != items {
timelineItems = items
}
})
.background(GeometryReader { geo in
Color.clear.preference(key: ViewFramePreferenceKey.self, value: [geo.frame(in: .global)])
})
.onPreferenceChange(ViewFramePreferenceKey.self) { _ in
guard bottomVisiblePublisher.value == true else {
return
}
.onChange(of: viewFrame) { _ in
// Use the cached version as visibleEdges will already have changed
// (but its onChange handler is yet to be called - possible race condition?)
guard cachedVisibleEdges.contains(.bottom) else { return }
// Pin the timeline to the bottom if was there on the frame change
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
@ -213,14 +197,6 @@ private struct PinnedItem: Equatable {
let animated: Bool
}
private struct ViewFramePreferenceKey: PreferenceKey {
static var defaultValue = [CGRect]() // Doesn't work with plain CGRects
static func reduce(value: inout [CGRect], nextValue: () -> [CGRect]) {
value += nextValue()
}
}
struct TimelineItemList_Previews: PreviewProvider {
static var previews: some View {
body.preferredColorScheme(.light)
@ -234,7 +210,7 @@ struct TimelineItemList_Previews: PreviewProvider {
mediaProvider: MockMediaProvider(),
roomName: nil)
TimelineItemList(bottomVisiblePublisher: CurrentValueSubject(false), scrollToBottomPublisher: PassthroughSubject())
TimelineItemList(visibleEdges: .constant([]), scrollToBottomPublisher: PassthroughSubject())
.environmentObject(viewModel.context)
}
}

View File

@ -0,0 +1,76 @@
//
// 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
struct VisibleEdgesKey: PreferenceKey {
static var defaultValue: [VerticalEdge] = []
static func reduce(value: inout [VerticalEdge], nextValue: () -> [VerticalEdge]) {
value = nextValue()
}
}
/// A SwiftUI scroll view with the following customisations for a room timeline
/// - The content is laid out starting at the bottom.
/// - Top and bottom edge visibility detection for triggering other behaviours.
struct TimelineScrollView<Content: View>: View {
@Binding var visibleEdges: [VerticalEdge]
@ViewBuilder var content: () -> Content
/// A small threshold added to the edge detection to allow a bit of leniency.
private let edgeDetectionThreshold: CGFloat = 15
var body: some View {
GeometryReader { scrollViewGeometry in
ScrollView {
VStack(alignment: .leading, spacing: 0) {
Spacer()
content()
}
.frame(minHeight: scrollViewGeometry.size.height)
.background {
GeometryReader { contentGeometry in
Color.clear
.preference(key: VisibleEdgesKey.self,
value: visibleEdges(of: contentGeometry, in: scrollViewGeometry))
}
.onPreferenceChange(VisibleEdgesKey.self) {
visibleEdges = $0
}
}
}
}
}
func visibleEdges(of contentGeometry: GeometryProxy, in scrollViewGeometry: GeometryProxy) -> [VerticalEdge] {
let frame = contentGeometry.frame(in: .global)
let isTopVisible = scrollViewGeometry.frame(in: .global).contains(CGPoint(x: frame.midX, y: frame.minY + edgeDetectionThreshold))
let isBottomVisible = scrollViewGeometry.frame(in: .global).contains(CGPoint(x: frame.midX, y: frame.maxY - edgeDetectionThreshold))
switch (isTopVisible, isBottomVisible) {
case (false, false):
return []
case (true, false):
return [.top]
case (false, true):
return [.bottom]
case (true, true):
return [.top, .bottom]
}
}
}

View File

@ -21,31 +21,29 @@ import SwiftUI
import Introspect
struct TimelineView: View {
@State private var bottomVisiblePublisher = CurrentValueSubject<Bool, Never>(true)
@State private var visibleEdges: [VerticalEdge] = []
@State private var scrollToBottomPublisher = PassthroughSubject<Void, Never>()
@State private var scollToBottomButtonVisible = false
@State private var scrollToBottomButtonVisible = false
var body: some View {
ZStack(alignment: .bottomTrailing) {
TimelineItemList(bottomVisiblePublisher: bottomVisiblePublisher, scrollToBottomPublisher: scrollToBottomPublisher)
TimelineItemList(visibleEdges: $visibleEdges, scrollToBottomPublisher: scrollToBottomPublisher)
scrollToBottomButton
}
}
@ViewBuilder
private var scrollToBottomButton: some View {
Button(action: {
scrollToBottomPublisher.send(())
}, label: {
Button { scrollToBottomPublisher.send(()) } label: {
Image(uiImage: Asset.Images.timelineScrollToBottom.image)
.shadow(radius: 2.0)
.padding()
})
.onReceive(bottomVisiblePublisher, perform: { visible in
scollToBottomButtonVisible = !visible
})
.opacity(scollToBottomButtonVisible ? 1.0 : 0.0)
.animation(.elementDefault, value: scollToBottomButtonVisible)
}
.onChange(of: visibleEdges) { edges in
scrollToBottomButtonVisible = !edges.contains(.bottom)
}
.opacity(scrollToBottomButtonVisible ? 1.0 : 0.0)
.animation(.elementDefault, value: scrollToBottomButtonVisible)
}
}

View File

@ -0,0 +1 @@
Swift from a LazyVStack to a VStack for the timeline.