feature<FileHistory>: add button to use selected revision of file

src/Commands/Checkout.cs

@@ -37,6 +37,11 @@ namespace SourceGit.Commands {
             return Exec();
         }
 
+        public bool FileWithRevision(string file, string revision) {
+            Args = $"checkout {revision} -- \"{file}\"";
+            return Exec();
+        }
+
         public bool Files(List<string> files) {
             StringBuilder builder = new StringBuilder();
             builder.Append("checkout -f -q --");

src/Resources/Locales/en_US.xaml

@@ -259,6 +259,7 @@
     <sys:String x:Key="Text.Fetch.Prune">Prune remote dead branches</sys:String>
 
     <sys:String x:Key="Text.FileHistory">File History</sys:String>
+    <sys:String x:Key="Text.FileHistory.UseThisVersion">USE THIS VERSION</sys:String>
 
     <sys:String x:Key="Text.ChangeDisplayMode">CHANGE DISPLAY MODE</sys:String>
     <sys:String x:Key="Text.ChangeDisplayMode.Grid">Show as Grid</sys:String>

src/Resources/Locales/zh_CN.xaml

@@ -258,6 +258,7 @@
     <sys:String x:Key="Text.Fetch.Prune">自动清理远程已删除分支</sys:String>
 
     <sys:String x:Key="Text.FileHistory">文件历史</sys:String>
+    <sys:String x:Key="Text.FileHistory.UseThisVersion">使用该版本</sys:String>
 
     <sys:String x:Key="Text.ChangeDisplayMode">切换变更显示模式</sys:String>
     <sys:String x:Key="Text.ChangeDisplayMode.Grid">网格模式</sys:String>

src/Views/FileHistories.xaml

@@ -131,7 +131,24 @@
             <GridSplitter Grid.Column="1" Width="1" HorizontalAlignment="Center" VerticalAlignment="Stretch" Background="Transparent"/>
 
             <!-- Diff Viewer -->
-            <widgets:DiffViewer Grid.Column="2" x:Name="diffViewer" Padding="4"/>
+            <Grid Grid.Column="2" Margin="4,4,4,0">
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="*"/>
+                    <RowDefinition Height="36"/>
+                </Grid.RowDefinitions>
+                
+                <widgets:DiffViewer Grid.Row="0" x:Name="diffViewer" />
+
+                <Button 
+                    Grid.Row="1"
+                    Height="30" 
+                    Padding="8,0"
+                    FontWeight="Bold"
+                    HorizontalAlignment="Center" VerticalAlignment="Center"
+                    Background="{DynamicResource Brush.Accent1}"
+                    Content="{DynamicResource Text.FileHistory.UseThisVersion}"
+                    Click="UseSelectedVersion"/>
+            </Grid>            
         </Grid>
     </Grid>
 </controls:Window>

src/Views/FileHistories.xaml.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
@@ -60,6 +61,24 @@ namespace SourceGit.Views {
             Models.Watcher.Get(repo).NavigateTo(e.Uri.OriginalString);
             e.Handled = true;
         }
+
+        private async void UseSelectedVersion(object sender, RoutedEventArgs e) {
+            var commit = commitList.SelectedItem as Models.Commit;
+            if (commit == null) return;
+
+            loading.IsAnimating = true;
+            loading.Visibility = Visibility.Visible;
+
+            await Task.Run(() => {
+                Models.Watcher.SetEnabled(repo, false);
+                new Commands.Checkout(repo).FileWithRevision(file, commit.SHA);
+                Models.Watcher.SetEnabled(repo, true);
+            });
+
+            loading.IsAnimating = false;
+            loading.Visibility = Visibility.Collapsed;
+            e.Handled = true;
+        }
         #endregion
     }
 }