feature: supports adding custom LFS track pattern

src/Resources/Locales/en_US.axaml

@@ -229,6 +229,10 @@
   <x:String x:Key="Text.GitFlow.StartReleaseTitle" xml:space="preserve">FLOW - Start Release</x:String>
   <x:String x:Key="Text.GitFlow.TagPrefix" xml:space="preserve">Version Tag Prefix:</x:String>
   <x:String x:Key="Text.GitLFS" xml:space="preserve">Git LFS</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern" xml:space="preserve">Add Track Pattern...</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.IsFilename" xml:space="preserve">Pattern is file name</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Pattern" xml:space="preserve">Custom Pattern:</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Title" xml:space="preserve">Add Track Pattern to Git LFS</x:String>
   <x:String x:Key="Text.GitLFS.Fetch" xml:space="preserve">Fetch</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Title" xml:space="preserve">Fetch LFS Objects</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Tips" xml:space="preserve">Run `git lfs fetch` to download Git LFS objects. This does not update the working copy.</x:String>

src/Resources/Locales/zh_CN.axaml

@@ -232,6 +232,10 @@
   <x:String x:Key="Text.GitFlow.StartReleaseTitle" xml:space="preserve">开始版本分支</x:String>
   <x:String x:Key="Text.GitFlow.TagPrefix" xml:space="preserve">版本标签前缀 ：</x:String>
   <x:String x:Key="Text.GitLFS" xml:space="preserve">Git LFS</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern" xml:space="preserve">添加追踪文件规则...</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.IsFilename" xml:space="preserve">匹配完整文件名</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Pattern" xml:space="preserve">规则 ：</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Title" xml:space="preserve">添加LFS追踪文件规则</x:String>
   <x:String x:Key="Text.GitLFS.Fetch" xml:space="preserve">拉取LFS对象 (fetch)</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Title" xml:space="preserve">拉取LFS对象</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Tips" xml:space="preserve">执行`git lfs prune`命令，下载远程LFS对象，但不会更新工作副本。</x:String>

src/Resources/Locales/zh_TW.axaml

@@ -232,6 +232,10 @@
   <x:String x:Key="Text.GitFlow.StartReleaseTitle" xml:space="preserve">開始版本分支</x:String>
   <x:String x:Key="Text.GitFlow.TagPrefix" xml:space="preserve">版本標籤字首 ：</x:String>
   <x:String x:Key="Text.GitLFS" xml:space="preserve">Git LFS</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern" xml:space="preserve">添加追蹤檔案規則...</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.IsFilename" xml:space="preserve">匹配完整檔案名</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Pattern" xml:space="preserve">規則 ：</x:String>
+  <x:String x:Key="Text.GitLFS.AddTrackPattern.Title" xml:space="preserve">添加LFS追蹤檔案規則</x:String>
   <x:String x:Key="Text.GitLFS.Fetch" xml:space="preserve">拉取LFS物件 (fetch)</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Title" xml:space="preserve">拉取LFS物件</x:String>
   <x:String x:Key="Text.GitLFS.Fetch.Tips" xml:space="preserve">執行`git lfs fetch`命令，下載遠端LFS物件，但不會更新工作副本。</x:String>

src/ViewModels/LFSTrackCustomPattern.cs

@@ -0,0 +1,43 @@
+using System.ComponentModel.DataAnnotations;
+using System.Threading.Tasks;
+
+namespace SourceGit.ViewModels
+{
+    public class LFSTrackCustomPattern : Popup
+    {
+        [Required(ErrorMessage = "LFS track pattern is required!!!")]
+        public string Pattern
+        {
+            get => _pattern;
+            set => SetProperty(ref _pattern, value, true);
+        }
+
+        public bool IsFilename
+        {
+            get;
+            set;
+        } = false;
+
+        public LFSTrackCustomPattern(Repository repo)
+        {
+            _repo = repo;
+            View = new Views.LFSTrackCustomPattern() { DataContext = this };
+        }
+
+        public override Task<bool> Sure()
+        {
+            _repo.SetWatcherEnabled(false);
+            ProgressDescription = "Adding custom LFS tracking pattern ...";
+
+            return Task.Run(() =>
+            {
+                var succ = new Commands.LFS(_repo.FullPath).Track(_pattern, IsFilename);
+                CallUIThread(() => _repo.SetWatcherEnabled(true));
+                return succ;
+            });
+        }
+
+        private readonly Repository _repo = null;
+        private string _pattern = string.Empty;
+    }
+}

src/ViewModels/Repository.cs

@@ -834,6 +834,19 @@ namespace SourceGit.ViewModels
             var lfs = new Commands.LFS(_fullpath);
             if (lfs.IsEnabled())
             {
+                var addPattern = new MenuItem();
+                addPattern.Header = App.Text("GitLFS.AddTrackPattern");
+                addPattern.Icon = App.CreateMenuIcon("Icons.File.Add");
+                addPattern.Click += (o, e) =>
+                {
+                    if (PopupHost.CanCreatePopup())
+                        PopupHost.ShowPopup(new LFSTrackCustomPattern(this));
+
+                    e.Handled = true;
+                };
+                menu.Items.Add(addPattern);
+                menu.Items.Add(new MenuItem() { Header = "-" });
+
                 var fetch = new MenuItem();
                 fetch.Header = App.Text("GitLFS.Fetch");
                 fetch.Icon = App.CreateMenuIcon("Icons.Fetch");

src/Views/LFSTrackCustomPattern.axaml

@@ -0,0 +1,33 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:m="using:SourceGit.Models"
+             xmlns:vm="using:SourceGit.ViewModels"
+             xmlns:v="using:SourceGit.Views"
+             xmlns:c="using:SourceGit.Converters"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="SourceGit.Views.LFSTrackCustomPattern"
+             x:DataType="vm:LFSTrackCustomPattern">
+  <StackPanel Orientation="Vertical" Margin="8,0">
+    <TextBlock FontSize="18"
+               Classes="bold"
+               Text="{DynamicResource Text.GitLFS.AddTrackPattern.Title}"/>
+    
+    <Grid Margin="0,16,0,0" RowDefinitions="32,32" ColumnDefinitions="150,*">
+      <TextBlock Grid.Row="0" Grid.Column="0"
+                 HorizontalAlignment="Right" VerticalAlignment="Center"
+                 Margin="0,0,8,0"
+                 Text="{DynamicResource Text.GitLFS.AddTrackPattern.Pattern}"/>
+      <TextBox Grid.Row="0" Grid.Column="1"
+               Height="28"
+               CornerRadius="3"
+               Text="{Binding Pattern, Mode=TwoWay}"
+               v:AutoFocusBehaviour.IsEnabled="True"/>
+
+      <CheckBox Grid.Row="1" Grid.Column="1"
+                Content="{DynamicResource Text.GitLFS.AddTrackPattern.IsFilename}"
+                IsChecked="{Binding IsFilename, Mode=TwoWay}"/>
+    </Grid>
+  </StackPanel>
+</UserControl>

src/Views/LFSTrackCustomPattern.axaml.cs

@@ -0,0 +1,12 @@
+using Avalonia.Controls;
+
+namespace SourceGit.Views
+{
+    public partial class LFSTrackCustomPattern : UserControl
+    {
+        public LFSTrackCustomPattern()
+        {
+            InitializeComponent();
+        }
+    }
+}