Improve load and switch logic between views

osu.Game.Tests/Visual/Online/TestSceneChangelogOverlay.cs

@@ -22,6 +22,8 @@ namespace osu.Game.Tests.Visual.Online
             typeof(StreamBadge),
             typeof(ChangelogHeader),
             typeof(ChangelogContent),
+            typeof(ChangelogListing),
+            typeof(ChangelogBuild),
             typeof(ChangelogContentGroup),
             typeof(Breadcrumb),
             typeof(BreadcrumbListing),

osu.Game/Overlays/Changelog/ChangelogBuild.cs

@@ -1,14 +1,18 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System.Threading;
+using System.Threading.Tasks;
 using osu.Framework.Allocation;
+using osu.Game.Online.API;
+using osu.Game.Online.API.Requests;
 using osu.Game.Online.API.Requests.Responses;
 
 namespace osu.Game.Overlays.Changelog
 {
     public class ChangelogBuild : ChangelogContent
     {
-        private readonly APIChangelogBuild changelogBuild;
+        private APIChangelogBuild changelogBuild;
 
         public ChangelogBuild(APIChangelogBuild changelogBuild)
         {
@@ -16,8 +20,24 @@ namespace osu.Game.Overlays.Changelog
         }
 
         [BackgroundDependencyLoader]
-        private void load()
+        private void load(CancellationToken? cancellation, IAPIProvider api)
         {
+            var req = new GetChangelogBuildRequest(changelogBuild.UpdateStream.Name, changelogBuild.Version);
+            bool complete = false;
+
+            req.Success += res =>
+            {
+                changelogBuild = res;
+                complete = true;
+            };
+
+            req.Failure += _ => complete = true;
+
+            api.Queue(req);
+
+            while (!complete && cancellation?.IsCancellationRequested != true)
+                Task.Delay(1);
+
             var changelogContentGroup = new ChangelogContentGroup(changelogBuild);
             changelogContentGroup.GenerateText(changelogBuild.ChangelogEntries);
             changelogContentGroup.UpdateChevronTooltips(changelogBuild.Versions.Previous?.DisplayVersion,

osu.Game/Overlays/Changelog/ChangelogContent.cs

@@ -10,7 +10,7 @@ namespace osu.Game.Overlays.Changelog
 {
     public class ChangelogContent : FillFlowContainer
     {
-        public event Action<APIChangelogBuild> BuildSelected;
+        public Action<APIChangelogBuild> BuildSelected;
 
         public void SelectBuild(APIChangelogBuild build) => BuildSelected?.Invoke(build);
 

osu.Game/Overlays/ChangelogOverlay.cs

@@ -2,6 +2,8 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
 using osu.Framework.Allocation;
 using osu.Framework.Audio;
 using osu.Framework.Audio.Sample;
@@ -24,7 +26,7 @@ namespace osu.Game.Overlays
 
         private BadgeDisplay badges;
 
-        private Container content;
+        private Container<ChangelogContent> content;
 
         private SampleChannel sampleBack;
 
@@ -58,7 +60,7 @@ namespace osu.Game.Overlays
                         {
                             header = new ChangelogHeader(),
                             badges = new BadgeDisplay(),
-                            content = new Container
+                            content = new Container<ChangelogContent>
                             {
                                 RelativeSizeAxes = Axes.X,
                                 AutoSizeAxes = Axes.Y,
@@ -103,7 +105,7 @@ namespace osu.Game.Overlays
             switch (action)
             {
                 case GlobalAction.Back:
-                    if (content.Child is ChangelogContent)
+                    if (content.Child is ChangelogListing)
                     {
                         State = Visibility.Hidden;
                     }
@@ -119,30 +121,14 @@ namespace osu.Game.Overlays
             return false;
         }
 
-        private void fetchListing()
-        {
-            header.ShowListing();
-
-            var req = new GetChangelogRequest();
-            req.Success += res =>
-            {
-                // remap streams to builds to ensure model equality
-                res.Builds.ForEach(b => b.UpdateStream = res.Streams.Find(s => s.Id == b.UpdateStream.Id));
-                res.Streams.ForEach(s => s.LatestBuild.UpdateStream = res.Streams.Find(s2 => s2.Id == s.LatestBuild.UpdateStream.Id));
-
-                builds = res.Builds;
-                ShowListing();
-                badges.Populate(res.Streams);
-            };
-
-            API.Queue(req);
-        }
-
         public void ShowListing()
         {
+            if (content.Children.FirstOrDefault() is ChangelogListing)
+                return;
+
             header.ShowListing();
             badges.Current.Value = null;
-            content.Child = new ChangelogListing(builds);
+            loadContent(new ChangelogListing(builds));
         }
 
         /// <summary>
@@ -162,17 +148,42 @@ namespace osu.Game.Overlays
             header.ShowBuild(build.UpdateStream.DisplayName, build.DisplayVersion);
             badges.Current.Value = build.UpdateStream;
 
-            void displayBuild(APIChangelogBuild populatedBuild) =>
+            loadContent(new ChangelogBuild(build));
-                content.Child = new ChangelogBuild(populatedBuild);
+        }
 
-            if (build.Versions != null)
+        private void fetchListing()
-                displayBuild(build);
-            else
         {
-                var req = new GetChangelogBuildRequest(build.UpdateStream.Name, build.Version);
+            var req = new GetChangelogRequest();
-                req.Success += displayBuild;
+            req.Success += res =>
+            {
+                // remap streams to builds to ensure model equality
+                res.Builds.ForEach(b => b.UpdateStream = res.Streams.Find(s => s.Id == b.UpdateStream.Id));
+                res.Streams.ForEach(s => s.LatestBuild.UpdateStream = res.Streams.Find(s2 => s2.Id == s.LatestBuild.UpdateStream.Id));
+
+                builds = res.Builds;
+                badges.Populate(res.Streams);
+
+                ShowListing();
+            };
+
             API.Queue(req);
         }
+
+        private CancellationTokenSource loadContentTask;
+
+        private void loadContent(ChangelogContent newContent)
+        {
+            content.FadeTo(0.2f, 300, Easing.OutQuint);
+
+            loadContentTask?.Cancel();
+
+            LoadComponentAsync(newContent, c =>
+            {
+                content.FadeIn(300, Easing.OutQuint);
+
+                c.BuildSelected = ShowBuild;
+                content.Child = c;
+            }, (loadContentTask = new CancellationTokenSource()).Token);
         }
     }
 }