Show the list of children in the commit details (#710)

* feature: add children list to the commit base info view

Useful for navigation between the commits.

* feature: use repository filters to limit children search
* feature: execute children search asynchronously
* feature: respect global commit limit for a good measure
* fix: input lines may contain several commits

The first commit is always the immediate child, so take only 40 initial characters of the line

* fix: hide children behind the preference
* feature: make parents and children scrollable

src/ViewModels/CommitDetail.cs

@@ -78,6 +78,12 @@ namespace SourceGit.ViewModels
             }
         }
 
+        public AvaloniaList<string> Children
+        {
+            get;
+            private set;
+        } = new AvaloniaList<string>();
+
         public string SearchChangeFilter
         {
             get => _searchChangeFilter;
@@ -515,6 +521,7 @@ namespace SourceGit.ViewModels
             VisibleChanges = null;
             SelectedChanges = null;
             ViewRevisionFileContent = null;
+            Children.Clear();
 
             if (_commit == null)
                 return;
@@ -535,6 +542,18 @@ namespace SourceGit.ViewModels
                 _cancelToken.Requested = true;
 
             _cancelToken = new Commands.Command.CancelToken();
+
+            if (Preference.Instance.ShowChildren)
+            {
+                Task.Run(() =>
+                {
+                    var cmdChildren = new Commands.QueryCommitChildren(_repo.FullPath, _commit.SHA, _repo.Settings.BuildHistoriesFilter()) { Cancel = _cancelToken };
+                    var children = cmdChildren.Result();
+                    if (!cmdChildren.Cancel.Requested)
+                        Dispatcher.UIThread.Post(() => Children.AddRange(children));
+                });
+            }
+
             Task.Run(() =>
             {
                 var parent = _commit.Parents.Count == 0 ? "4b825dc642cb6eb9a060e54bf8d69288fbee4904" : _commit.Parents[0];

src/ViewModels/Preference.cs

@@ -294,6 +294,12 @@ namespace SourceGit.ViewModels
             set => SetProperty(ref _statisticsSampleColor, value);
         }
 
+        public bool ShowChildren
+        {
+            get => _showChildren;
+            set => SetProperty(ref _showChildren, value);
+        }
+
         public List<RepositoryNode> RepositoryNodes
         {
             get;
@@ -617,5 +623,7 @@ namespace SourceGit.ViewModels
         private string _externalMergeToolPath = string.Empty;
 
         private uint _statisticsSampleColor = 0xFF00FF00;
+
+        private bool _showChildren = false;
     }
 }